Like any theory, Darwin’s idea that evolution proceeds through natural selection was once merely a hypothesis. In this post, we’ll look at some of the early observations Darwin made on biogeography: the study of where species are distributed across the globe. These lines of evidence would later prod him to consider the possibility that species arise through a natural process of gradual change over time, rather than being independently created in each location where they are found.

The curious case of the missing mammals

As a widely-travelled naturalist on the HMS Beagle, Darwin studied a large number of different environments and documented the species he found in each. The Beagle, engaged as it was in an effort to map the coastline of South America, naturally paid call to numerous island groups along the way, including islands at a great distance from a continent (i.e.oceanic islands). One observation that Darwin made about oceanic islands is that none that he studied had terrestrial mammals on them. Later work, after his voyage, would confirm that this was a general rule. Oceanic islands lack terrestrial mammal species, except for small species that were introduced by humans. In contrast, flying mammals (i.e. bats) were found on oceanic islands, and often these species were endemic (i.e. found nowhere else in the world but the island in question).

Darwin found these observations difficult to square with his (then) working assumption that species were independently created in (and specifically created for) the locations in which they are found across the globe. He discusses these observations, and the questions they raised in his mind, in two chapters entitled “Geographical Distribution” in his Origin of Species. After discussing the similar case that amphibians (such as frogs, newts, and so on) are also not to be found on oceanic islands, he turns his attention to the missing mammals:

Mammals offer another and similar case. I have carefully searched the oldest voyages, but have not finished my search; as yet I have not found a single instance, free from doubt, of a terrestrial mammal (excluding domesticated animals kept by the natives) inhabiting an island situated above 300 miles from a continent or great continental island.... It cannot be said, on the ordinary view of creation, that there has not been time for the creation of mammals; many volcanic islands are sufficiently ancient, as shown by the stupendous degradation which they have suffered and by their tertiary strata: there has also been time for the production of endemic species belonging to other classes; and on continents it is thought that mammals appear and disappear at a quicker rate than other and lower animals. Though terrestrial mammals do not occur on oceanic islands, aërial mammals do occur on almost every island. New Zealand possesses two bats found nowhere else in the world: Norfolk Island, the Viti Archipelago, the Bonin Islands, the Caroline and Marianne Archipelagoes, and Mauritius, all possess their peculiar bats. Why, it may be asked, has the supposed creative force produced bats and no other mammals on remote islands? On my view this question can easily be answered; for no terrestrial mammal can be transported across a wide space of sea, but bats can fly across. Bats have been seen wandering by day far over the Atlantic Ocean; and two North American species either regularly or occasionally visit Bermuda, at the distance of 600 miles from the mainland. I hear from Mr. Tomes, who has specially studied this family, that many of the same species have enormous ranges, and are found on continents and on far distant islands. Hence we have only to suppose that such wandering species have been modified through natural selection in their new homes in relation to their new position, and we can understand the presence of endemic bats on islands, with the absence of all terrestrial mammals.

(As an aside, it’s important to note that Darwin, when he discusses the “supposed creative force” is not here arguing against the existence of God as creator in general, but rather against the “ordinary view of creation” common at the time: that God had episodically created species at specific geographical locations (what were called “centers of creation”) and that biogeographical patterns could be explained with limited dispersal from those centers. Darwin himself held to this common view at the start of his voyage on the Beagle, and that is the model he is attempting to refute in Origin, since it was a prevailing view among scientists at the time. Darwin and many of his scientific contemporaries also had no difficulty viewing natural processes as part of God’s regular action in the world, as is evident in Darwin’s correspondence with American botanist Asa Gray, among others.)

So, for Darwin, his biogeographical observations sat at ease with his (later) ideas of colonization and subsequent species change through natural selection, but made no sense to him if one held to an independent creation model. Many oceanic islands were very old, yet no mammals had been created there. Many oceanic islands had habitat suitable for mammals (or, indeed, for amphibians, as he notes) yet no such species had been created for that suitable habitat.

Island endemics and their continental “allied species”

Darwin noticed more than the absence of certain species groups on oceanic islands. He also noticed an interesting feature of the species that were present: an endemic species on an oceanic island would often have strong similarities with a species on the mainland closest to the island in question. Additionally, the pairing of oceanic endemic species with continental species often seemed to override expectations that species found in similar environments would be more similar to each other. These observations prompted him to reflect further on the possible means by which these “closely allied species” arose. As Darwin would write in his Origin this repeated pattern made a significant impression on him, and further caused him to doubt that endemic species had been individually created for each oceanic island. His visit to the Galapagos would prove instrumental on this point:

The most striking and important fact for us in regard to the inhabitants of islands, is their affinity to those of the nearest mainland, without being actually the same species. Numerous instances could be given of this fact. I will give only one, that of the Galapagos Archipelago, situated under the equator, between 500 and 600 miles from the shores of South America. Here almost every product of the land and water bears the unmistakeable stamp of the American continent. There are twenty-six land birds, and twenty-five of these are ranked by Mr. Gould as distinct species, supposed to have been created here; yet the close affinity of most of these birds to American species in every character, in their habits, gestures, and tones of voice, was manifest. So it is with the other animals, and with nearly all the plants, as shown by Dr. Hooker in his admirable memoir on the Flora of this archipelago. The naturalist, looking at the inhabitants of these volcanic islands in the Pacific, distant several hundred miles from the continent, yet feels that he is standing on American land. Why should this be so? why should the species which are supposed to have been created in the Galapagos Archipelago, and nowhere else, bear so plain a stamp of affinity to those created in America? There is nothing in the conditions of life, in the geological nature of the islands, in their height or climate, or in the proportions in which the several classes are associated together, which resembles closely the conditions of the South American coast: in fact there is a considerable dissimilarity in all these respects. On the other hand, there is a considerable degree of resemblance in the volcanic nature of the soil, in climate, height, and size of the islands, between the Galapagos and Cape de Verde Archipelagos: but what an entire and absolute difference in their inhabitants! The inhabitants of the Cape de Verde Islands are related to those of Africa, like those of the Galapagos to America. I believe this grand fact can receive no sort of explanation on the ordinary view of independent creation; whereas on the view here maintained, it is obvious that the Galapagos Islands would be likely to receive colonists, whether by occasional means of transport or by formerly continuous land, from America; and the Cape de Verde Islands from Africa; and that such colonists would be liable to modification;—the principle of inheritance still betraying their original birthplace.

Many analogous facts could be given: indeed it is an almost universal rule that the endemic productions of islands are related to those of the nearest continent, or of other near islands.

Rethinking independent creation

For Darwin, both of these observations (that oceanic islands lacked terrestrial mammals, and that endemic species on islands were most similar to a species on the closest mainland) had the same explanation: his hypothesis that endemic, oceanic species were the modified descendants of a colonizing species from the nearest continent. This also explained the lack of amphibians and terrestrial mammals (but allowed for bats) - simply based on the ability of these classes of life to disperse across large expanses of ocean. Those that could disperse and colonize oceanic islands would experience modification in the new environment, and species unable to colonize these islands would never appear. To Darwin’s thinking, this explanation was wholly more satisfactory than the assumption that God had independently created every endemic species in its place, and arbitrarily chosen that oceanic islands did not need terrestrial mammals and amphibians.

Despite Darwin’s musing on the biogeographical patterns he observed, and the strong suggestion these patterns made of species change over time, a mechanism for that change would take some time for him to imagine. In our next post, we’ll look at that mechanism: Darwin’s idea of natural selection, and the evidence he assembled in its support prior to publishing the Origin.

Grantees will benefit from in-person interaction through a series of summer workshops in 2013, 2014, and 2015. These meetings will not only foster a broader knowledge base, but will build a sustained network of scholars and church leaders, both young and seasoned, who are serious about addressing the concerns of the church about evolution. Also in 2015, in connection with the third summer workshop, BioLogos will host a large conference open to scientists, scholars, and church leaders from around the world.

ECF History

In January 2012, BioLogos was awarded a multi-million dollar grant from the John Templeton Foundation to fund the work of scholars and church leaders on evolution and Christian faith. In spring 2012 we worked hard to get the word out. You may have seen announcements on the BioLogos website, in our newsletters, on the Books & Culture, Leadership Journal, or First Things websites, on your professional society’s listserv, or perhaps on your friend’s blog.

The response was overwhelming: we received 225 letters of intent for a total request of $21 million—about seven times the amount we had to offer. We needed to invite the most promising applicants to submit a full proposal, but recognizing the projects with highest potential would require broad expertise. From the beginning, we envisioned that a panel of scientists, pastors, and scholars would oversee the application and review process as well as play key advisory roles throughout the project. A team of eight highly qualified individuals came on board in the early months of the project. They reviewed each proposal and together recommended that BioLogos invite 86 applicants to submit full applications.

The deadline for submissions was October 1, 2012. As in the previous round, the ECF panel evaluated each proposal. In addition, we asked 55 other experts to participate, so that each proposal received 3-4 scores. Criteria for the decision included significance of topic, project design, creativity and innovation, long-term impact potential, feasibility, and budget.

The panel then met together November 29-30, 2012, to make the final funding decisions. In the end, they recommended that BioLogos give 37 awards, ranging from $23,000 to $300,000. BioLogos staff notified applicants of their awards on December 14, 2013.

The Grantees

As part of our objective to create a network of scholars and leaders, we awarded grants to organizations across the U.S. and the world. Thirty of the 37 grantees are domestic; seven are international, hailing from Canada, France, Great Britain, Netherlands, and Spain.

Two-thirds of the accepted projects will be led by teams—some with three or more Project Leaders. We expect that the teamwork and time spent together at our summer workshops will be the start of a long-lasting network of people dedicated to helping the church think carefully about origins.

Applicants chose to apply under one of three program tracks: interdisciplinary scholarship (Track 1), intra-disciplinary scholarship (Track 2), and translational projects (Track 3). Track 1 projects focus on both the collaboration between individuals in different disciplines and the development of projects at the interface of different content areas. Track 2 projects focus on work done within a specific discipline. Track 3 focuses on projects that encourage Christians, especially those within more conservative traditions, to engage in meaningful and productive dialogue to reduce tensions between mainstream science and the Christian faith. The numbers of grantees in Tracks 1, 2, and 3 are 6, 8, and 23, respectively.

Many of the scholarly projects tackle questions about Adam and Eve, the Fall, human identity, and Original Sin—some of the most critical interpretive issues for evangelical theology.  Some examples: 

• Theologian Oliver Crisp of Fuller Seminary will take an analytic theology approach to ask to what extent a theological account of the origin of human sin depends upon the evolution of modern humans from one and only one ancestral pair—especially if that pair does not appear to correspond to what we would think of as modern human beings. 

• Pastor Michael Gulker and philosopher James Smith, leading a large team from The Colossian Forum, ask a related question: if humanity emerged from non-human primates—as genetic, biological, and archaeological evidence seems to suggest—then what are the implications for Christian theology’s traditional account of origins, including both the origin of humanity and the origin of sin? 

• Biologist Dennis Venema of Trinity Western University and New Testament scholar Scot McKnight of Northern Seminary will write a book on the evidence for evolution and population genetics, with informed theological reflection on how these issues interact with orthodox Christianity.

• Biologist David Wilcox of Eastern University will develop an updated model of human identity which reflects the complex recent scientific advances in genetics and paleoanthropology and yet is sensitive to theological concerns.  

These are just a few of the scholarly awards; check out the Grantees page for full descriptions of all Track 1 and Track 2 projects.

All projects have translational potential, but Track 3 projects are designed to meet the needs of a particular constituency within the evangelical church. These projects run the gamut from ethics to education to media production to ministry resources.  Some examples include:

• Theologian Lee Camp of Lipscomb University will produce “The Questions in Monkey Town,” an episode of Tokens, a live variety show that features musical performances, comedic sketches, brief interpretive monologues, and dialog with authors and scholars. The episode will be performed and filmed on the site of the famous Scopes Trial in Dayton, Tennessee.

• Chaplain Joshua Hayashi and Educator Diane Sweeney of the Punahou School in Hawaii will lead a team to produce multimedia curricula aimed at helping high school students connect with their biology curricula and, at the same time, deepen their Christian faith.

• Physics teacher and pastor Benoît Hébert of Science et Foi Chrétienne in France will lead an international, multi-denominational team of French speaking Evangelical scientists, pastors and church leaders to produce a large number of resources on evolutionary creation.

• Pastor Seung-Hwan Kim of Grace Truth Community Church, a Southern Baptist church in Cambridge, Massachusetts, will produce teaching and preaching materials about evolution for church leaders.

• President Gregory Wolfe and Director of Resource Development for IMAGE will gather artists and writers of faith whose work explores the dialogue between evolutionary science and faith practice, convening a conversation between them and scientists, theologians, and church leaders in private and public conferences.

Again, this is just a taste of the diversity of Track 3 projects. Read more about each project on the Grantees page. You can look forward to an incredible variety of resources coming out of the ECF program, many of which will be featured right here on the BioLogos Forum.

A common argument leveled against the theory of evolution is that scientists have not been able to produce the expected transitional fossils that show the change of one species into another. If evolution were true, wouldn’t there be instances of clear intermediary species, like, for example, a species that was half whale and half hippo to show the transition between those two? In this BioLogos podcast, Kelsey Luoma addresses this misconception about what a transitional fossil actually is. Rather than a mix between two related species, transitional fossils point back to the common ancestors that modern species share. The fact is that the number of transitional species is massive and it grows with each passing year. Given the rarity with which organisms are actually fossilized, the amazing thing is actually the completeness of the fossil record, not its incompleteness. The transitional species story strongly supports, and certainly does not disprove, evolutionary theory. ¹

1. To hear the full audio clips which have been referenced go to:

• Rational Response Debate with Kirk Cameron (from Way of the Masters)
• Behind the Scenes with Dr. Neil Shubin (from Cincinnati Museum Center)
• Mark Norell Publishes New Archaeopteryx Findings (from American Museum of Natural Sciences)
• Texas A&M Professor Discusses Findings of Autralopithecus Sediba and its Relationship to Humans (from Texas A&M University)
• Intro/outro music composed by Martin Minor (Minor2Go).

An audio only version of the podcast can be downloaded here.

According to Merriam Webster, the term “intelligent design” has been used since at least 1847, in reference to “the theory that matter, the various forms of life, and the world were created by a designing intelligence.” That’s a decent definition, also consistent with those offered by today’s proponents of intelligent design (ID). For example, the leading ID think tank, The Discovery Institute (Seattle), has this:

Intelligent design refers to a scientific research program as well as a community of scientists, philosophers and other scholars who seek evidence of design in nature. The theory of intelligent design holds that certain features of the universe and of living things are best explained by an intelligent cause, not an undirected process such as natural selection.

And in the opening sentence of a book he edited with philosopher Michael Ruse, ID theorist William Dembski said, “Intelligent Design is the hypothesis that in order to explain life it is necessary to suppose the action of an unevolved intelligence.” (Debating Design, p. 3)

On the other hand, while a recent contest on a prominent intelligent design (ID) website uncovered several other early uses of the term, it is important to note that it does not always mean exactly the same thing in each reference. The term itself has an interesting history, and while ID authors obviously did not invent the term “intelligent design,” they have given it specific content in recent years. Indeed, they have even removed content in some cases: a point I will return to later is that, though it seems the only viable candidate for such an “unevolved intelligence” is God, ID proponents sometimes seem to do cartwheels to avoid saying as much. When a term has such a complicated past, there simply is no substitute for looking at specific references in their own contexts as we move to seeing how ID plays out today as one of the 5 ways of relating science and the Bible.

Interestingly, many Protestant “modernist” scientists and theologians from William Jennings Bryan’s day (see my previous column) unhesitatingly endorsed the idea that a designing intelligence lay behind nature. At least one such person, Nobel prize-winning physicist Arthur Holly Compton, even used the very term “intelligent design” in an address he gave at a Unitarian church in 1940: “The chance of a world such as ours occurring without intelligent design becomes more and more remote as we learn of its wonders.” (Quoting his pamphlet from 1940, The Idea of God as Affected by Modern Knowledge, p. 13. For more about this aspect of Compton’s views, click here.) However, Compton regarded design as a philosophical and theological inference from science, not an explanation within science to be invoked when other explanations fail. He also accepted the common ancestry of humans and other organisms. This is a significant difference from the ID movement today, which offers ID as a scientific alternative to Darwinian evolution and (at least in many cases) seeks to undermine public confidence in common ancestry (even though ID per se is not actually opposed to it).

If any ID proponents are sympathetic to the type of religious modernism that Compton and his friends embraced, I cannot tell you who they are. In a curious, ironic twist, ID is often used by conservative Christian apologists partly to defend a cluster of traditional theological and hermeneutical positions that none of the modernists would have defended. A further irony: the intellectual descendants of the modernists—those scientists and theologians who occupy the left wing of the modern “dialogue” of science and religion—exhibit a studied avoidance of the term “design,” disconnecting them on that score from the modernists of the 1920s.

Many other contemporary writers, including some evangelical TEs, are also reluctant to use the word “design,” precisely because in their view it has been co-opted by ID proponents and they do not want readers to misunderstand their position(s). They may agree with ID proponents that certain features of the universe reflect divine design, but because they do not see design as a scientific explanation they employ other language. (Likewise, the YECs have co-opted the word “creationism” to mean just one specific understanding of God’s creative activity, leading most advocates of other views either to provide their own definitions of the word or else to avoid using it altogether. Politics dogs this conversation at every turn.)

Core Tenets or Assumptions of Intelligent Design

With that bit of historical context for the term “Intelligent Design,” let’s now look at the first of the Core Tenets of this perspective in its current state, and as it is most often used by those associated with the Intelligent Design movement.

(1) The Bible is NOT to be mentioned (at least for now); ditto for “God” and “theology” as far as possible.

This is a deliberate strategy, adopted for political reasons to keep arguments at the level of philosophy and science. Here, “political” refers to the American political system, with its constitutional disestablishment of religion, not to partisan politics. Since the 1980s, federal courts have consistently ruled that “creationism” (which was specifically of the YEC variety in the relevant cases) is sectarian religion, not science, and therefore it cannot be taught in public school science classes. Anxious to avoid a similar fate, proponents of ID always want to ensure that they are not perceived as advocates of “creationism.” The less they mention God and the Bible, the reasoning goes, the less likely they are to fall afoul of those decisions.

The First Amendment to the U.S. Constitution, pertaining to the freedom of religion and the freedom of the press.
Source: http://www.rochester.edu/college/psc/images/Courses/Spring2008/FirstAmendment.png

Phillip Johnson, the former law professor who effectively began the ID movement some twenty years ago, has put it bluntly: “To put things on a more rational basis, the first thing that has to be done is to get the Bible out of the discussion.” He quickly adds, “This is not to say that the biblical issues are unimportant; the point is rather that the time to address them will be after we have separated materialist prejudice from scientific fact.” (“The Wedge: Breaking the Modernist Monopoly on Science,” Touchstone: A Journal of Mere Christianity, July/August 1999, p. 22.)

If God and the Bible are really to be left out for the time being, then why am I discussing ID in a series on “Science and the Bible”? It’s a fair question. I simply don’t see any way meaningfully to avoid talking about ID apart from the culture wars in which it is embedded (I’ll say more about this in a subsequent column), and the Bible is never far from the surface when the battle being fought involves origins. Conservative Christians sense that ID really is about God—Dembski’s “unevolved intelligence”. As Dembski himself has said, “no intelligent agent who is strictly physical could have presided over the origin of the universe or the origin of life”, and there aren’t a lot of candidates for that job. Many Christians also identify strongly with the ways in which ID seeks to confront the secular establishment, in an explicitly-stated effort to combat what Johnson calls “the modernist scientific and intellectual world, with its materialist assumptions.” (“The Wedge,” p. 23.) They see it as a way of getting traditional theistic perspectives and Christian values back into the academy, once “design” has become an acceptable academic talking point—and it isn’t very far from there to conversations about “science and the Bible.” If this were not so, then why would so much ID literature be published by Christian presses? Indeed, when I tell church audiences with a straight face that ID purports not to be about the Bible at all, I’m usually met with considerable skepticism.

When I’m back in about two weeks, we’ll look at further Core Tenets of ID—the ones that have even less to do with the Bible, explicitly, and more to do with the way we approach the study of the natural world.

With the complete genome sequence in hand, we knew the sequence and location of our genes, but what we didn’t know was how all those genes are regulated: how do the trillions of cells in our bodies know when to turn on or off all those genes? How do the hundreds of distinct cell types develop and function together, when they are all running on the same DNA “operating system?”

That’s where the ENCODE (short for Encyclopedia of DNA Elements) project comes in. Launched in September 2003, shortly after the announced completion of the Human Genome Project, the goal of the ENCODE project is “to build a comprehensive parts list of functional elements in the human genome, including elements that act at the protein and RNA levels, and regulatory elements that control cells and circumstances in which a gene is active.” In other words, the project seeks to understand how the genome “works.”

Early this month, researchers from ENCODE released more than thirty papers presenting their findings. During a Science magazine online chat, the project’s data coordinator, Ewan Birney, explained the outcome:

The ENCODE project aimed to start our understanding of how the human genome works. We know that (nearly) all the information that determines a human is in the genome, as we all start off as single cell with this DNA. However, we had a patchy understanding of how it works, in particular away from protein coding genes.

To work out how the genome works, we used the fact there are many tiny machines (proteins and RNA - RNA is very like DNA) in each of our cells which know how to "read" parts of the genome. By monitoring where these little molecular machines are on the genome, or how parts of the DNA are copied into RNA (there are quite a few different types of RNA as well), we start to gain some insight into the genome.

We did many such experiments, across different cell types (eg, one cell type was very similar to a liver cell type; another was very similar to a white blood cell). This way not only can we see what is similar, we can also see differences between these cell types.

There is a lot more to get to know and understand here - this is definitely closer to the start than the end. But it is a substantial amount of data, and analysis, to start on this journey.

According to the abstract of one of the lead papers from Nature, this extraordinary glut of data “enabled us to assign biochemical functions for 80% of the genome, in particular outside of the well-studied protein-coding regions.” Only 2% of the genome codes for proteins, but 80% or more has some biochemical function. As a Science news article put it, these 30 papers “sound the death knell for the idea that our DNA is mostly littered with useless bases.”

The pro-Intelligent Design organization The Discovery Institute has heralded the discovery as the “demise of junk DNA.” Casey Luskin writes for their blog Evolution News:

Let's simply observe that it provides a stunning vindication of the prediction of intelligent design that the genome will turn out to have mass functionality for so-called "junk" DNA. ENCODE researchers use words like "surprising" or "unprecedented." They talk about of how "human DNA is a lot more active than we expected." But under an intelligent design paradigm, none of this is surprising. In fact, it is exactly what ID predicted.

The extent to which the ENCODE project been able to identify function has been surprising—even exhilarating—though scientists have for some time been getting glimpses of the many ways in which segments of DNA can be “active.” Even in 1970 biologists knew that some non-coding DNA had function, and by 2003 there was a large body of work demonstrating that many non-coding elements acted as promoters, enhancers, insulators, and so on. Indeed, in recent years many have come to appreciate the fact that “junk” was never really an appropriate metaphor in the first place. Still, because sequencing of multiple genomes has shed such extraordinary light on key evolutionary mechanisms, many geneticists have focused on function primarily in terms of which regions do or do not contribute to the evolutionary fitness of their host, rather than whether they were merely "doing something" biochemically. What the impressive ENCODE project has done is open a treasure trove of new information that can only accelerate the pace at which researchers are able to explore the incredible subtlety and complexity of DNA, and refine the very concept of “functionality.”

So with all this in mind, is ENCODE a stunning victory for ID, as Luskin believes? Bryan College biologist Todd Wood thinks not. He writes, “I don't think that function equates to design, nor do I think that design requires or predicts function. They're not the same thing… my understanding of function does not require me to hypothesize God (or an anonymous designer, if you must) as the proximal cause.”

We agree. Indeed we would go on to say that evolution and design are not mutually exclusive. So while finding function is not sufficient to prove design, recognizing that function has arisen by way of evolution does not indicate that God was not at work. We at BioLogos believe God providentially works out his purposes—his designs—through the elegant processes of evolution, not in opposition to them.

Amazing as the new data are, it only strengthens and enhances our evidence for evolution. While much of the genome is “doing something” biochemically, it is still likely that the majority of the sequence is evolutionarily neutral (Senior Fellow Dennis Venema discusses the evidence for this “neutrality” in a post on our site, including a striking comparison between 29 different mammal genomes and the human genome). In fact, another ENCODE researcher participating in the Science magazine chat, John A. Stamatoyannopoulos of the University of Washington School of Medicine, thinks the findings align beautifully with evolutionary theory:

ENCODE's data provide a unique and powerful window through which to view evolutionary change. We can see those changes directly by lining up the genome sequences of many different organisms -- these line-ups have revealed millions of regions where all the genomes agree, indicating sequences that have been specially preserved by evolution while others have decayed away (ie freely changed their letter codes). We now see that a large proportion of these 'conserved' regions are lighted up by ENCODE annotations, indicating that they are marking spots in the genome that contain important instructions for cell function.

We’ve discussed “junk” DNA previously, including a multi-part series by Dennis Venema, and we’ve received many emails over the past few days asking for our comments on the ENCODE findings. On Monday and Tuesday, Dr. Venema will begin to offer his own thoughts on ENCODE.

A special thanks goes to Darrel Falk, Mark Sprinkle, Kathryn Applegate, Dennis Venema, and Tom Burnett for their contributions to this post.

The Denisovans, an extinct hominid group that interbred with modern humans, made the news again lately with the publication of a more detailed study of their genome. One of the many interesting findings was that the Denisovans share the same chromosome 2 fusion that modern humans have. In this post, I review what we know about the origins of human chromosome 2, and then discuss the new Denisovan findings and their implications.

The origins of human chromosome 2: a brief review

Though I have discussed the evidence for a fusion event leading to human chromosome 2 before, perhaps a brief review of the evidence is in order. The human genome is made up of 23 pairs of chromosomes (for a total of 46 chromosomes). This makes us something of an oddity among living great apes, all the rest of whom have 24 pairs of chromosomes (for a total of 48). Given that there are many independent lines of evidence that support the conclusion that we share a common ancestor with other great apes, this poses something of a conundrum: how is it that our species arrived at this specific chromosome number? If we were to represent this “problem” on a phylogeny, or tree of relatedness, it would look something like this (not to scale):

Our closest living relatives, chimpanzees and bonobos, both have 48 chromosomes, as do all other great apes such as gorillas and orangutans. This pattern has one of two explanations, one of which is much more likely than the other. Either the common ancestor to these species had 48 chromosomes, and there was an event that reduced that number to 46 specifically on the lineage leading to humans (option A), or the common ancestor species had 46 chromosomes, and there were independent, repeated events that increased chromosome number in all other great ape species (option B). We can compare these options by placing the required event(s) on the phylogeny (again, not to scale):

It should be obvious that the option that requires the fewest events is the more likely one – in this case option A with an event that reduces chromosome number in the lineage leading to humans. The other option, that of repeated, independent events to increase chromosome number, remains a formal, but unlikely, possibility. Events that reduce chromosome number are not frequent occurrences, so Option A is more likely than Option B.

We can also find further support for Option A, because it predicts a specific type of event, namely one that reduces chromosome number. Since loss of a large amount of chromosomal material is almost always detrimental, we need an event that reduces chromosome number without losing information. One way for this to happen is for two chromosomes to fuse together and become one. Initially, this event would produce an individual with 47 chromosomes, where two different chromosomes get stuck together. Contrary to what is often assumed, this individual would be fertile and able to interbreed with the others in his or her population (who continue to have 48 chromosomes). In a small population, over time, two relatives who both have one copy of the fusion chromosome may mate and produce some progeny with two copies of the fused chromosome, or the first individuals with 46 chromosomes. Since either a 48-pair set or a 46-pair set is preferable for ease of cell division, this population will either eventually get rid of the fusion variant (the most likely outcome), or by chance will switch over completely to the “new” form, with everyone bearing 46 chromosome pairs. While not overly likely, this type of event is not especially rare in mammals, and we have observed this sort of thing happening within recorded human history in other species. Some mammalian species even maintain distinct populations in the wild with differing chromosome numbers due to fusions, and these populations retain the ability to interbreed.

Further evidence for a fusion event in the lineage leading to modern humans comes from comparing synteny, or gene locations and orders on chromosomes within modern great apes – an issue we have discussed here before. In brief, what we see in human chromosome 2 is exactly what we would predict for a fusion event. When compared to other great apes, we see the genes on human chromosome 2 match up, in order, with two smaller ape chromosomes. We also see that sequences used at the tips of chromosomes are present at the proposed fusion site, and that human chromosome 2 has not one but two sites for the cell cytoskeleton to attach to for cell division – but that one of the sites is mutated and not functional, though it lines up precisely with the location of this site on the appropriate ape chromosome. Together, this evidence consistently supports both common ancestry for humans and great apes, and specifically that the difference we see in our chromosome numbers arose due to a single fusion event. I briefly discussed this evidence in my last post where I describe how I teach some of this material and the compelling impact it has on students exploring the evolution question for the first time.

Enter the Denisovans

With that as background, we are now prepared to appreciate a new finding that comes from genomics work done on the Denisovan hominids, an archaic species that is more closely related to Neanderthals than to us, but that nonetheless interbred with some anatomically modern humans as they migrated out of Africa and populated the globe. (For those not familiar with the Denisovans, or the evidence for our interbreeding with them, both Darrel Falk and I have written on this previously, here and here). Recently, a more detailed understanding of the Denisovan genome was published, and nested in the new information is the discovery that the Denisovans share the 46 chromosome set with the same fusion that we have. This strongly supports the hypothesis that the fusion event predates the separation of our species. If we were to represent this on a phylogeny, we can now place this event with more accuracy than before (as before, the phylogeny is not to scale):

Despite this new information, one obvious question remains. Did the Neanderthals also have the 46-pair set? From looking at the phylogeny above, we can see that the most likely answer is that they did, since the fact that the Denisovans had it strongly implies that the last common ancestor of humans and Neanderthals / Denisovans had it as well, and the Neanderthal-Denisovan split comes later. While the Denisovan DNA samples are of high enough quality to make this assessment, we do not yet have Neanderthal DNA of high enough quality to do the same analysis with current methods (though one additional feature of the new work on the Denisovan genome is developing more sensitive DNA sequencing techniques that may resolve this question in the future).

In other words, this fusion seems to be an ancient one, predating our species by several hundred thousand years. Present estimates of the last common ancestor between humans and Neanderthals / Denisovans range at about 800,000 years ago.

Implications for understanding our “becoming human”

The main implication from this work is that it places the fusion event well before the advent of our species. I’ve often chatted informally with Christians about evolution, and at times some have thought that this fusion event was what “started” our species, or made our species unable to interbreed with other groups. Some have even suggested that perhaps the fusion event was what produced the first human (i.e. Adam).

Note that thinking this way suggests a misunderstanding of how chromosome fusions occur and what effect they have on their hosts. A fusion does not precipitate a speciation event, but rather the individual with the fusion remains a part of his or her population, and able to interbreed, even if with reduced fertility. Also, there is no necessary biological effect or change that the fusion produces on the appearance of the organism. These misunderstandings aside, however,what this new evidence shows is that this fusion event took place long before modern humans arose at around 200,000 years ago. Indeed, the 800,000 years ago date for the last human - Denisovan common ancestor means that this is the most recent date possible for the fusion. While it is an interesting piece of our evolutionary history, it doesn’t seem to have much to do with how we came to acquire the traits that set us apart from, and ultimately outcompete, other similar species.

Asa Gray

If Thomas Huxley earned the title of "Darwin's bulldog," then Asa Gray should be remembered as "Darwin's dove." Whereas Huxley enjoyed a good fight in his defense of Darwin's theory, Gray sought to mediate and bring sides together around a common understanding of "good science." As Darwin's strongest and most vocal scientific ally in the United States, Gray recognized the scientific importance of Darwin's efforts for the growing professionalism of biological researchers.

But as an orthodox Christian, a Presbyterian firmly devoted to the faith expressed in the Nicene Creed, Gray saw in Darwin's theory both evidence for his philosophical commitment to natural theology and support for his opposition to the idealism advocated by Louis Agassiz and the Naturphilosophen in both Europe and America. Indeed, Agassiz's advocacy of Platonic forms as a basis of biological understanding (e.g., "A species is a thought of the creator")¹ would be a major source of American opposition to Darwin's theory.

Professor of botany at Harvard during most of the middle half of the nineteenth century, Gray was one of the few members of the scientific community to whom Darwin revealed his theory before the publication of On the Origin of Species, and, from what I can tell, the only American. Gray and Darwin met briefly in January 1839 during one of Gray's visits to England. Later, during the 1850s, Darwin wrote Gray on several occasions requesting information--a practice that Darwin frequently employed. In 1854, Darwin's friend and confidant, Joseph Hooker, showed Darwin Gray's review of Hooker's Flora of New Zealand, in which Gray had argued strongly against Louis Agassiz's idealism and had raised questions from his own work on the stability of species. Gray was not yet ready to deny their permanence, but hybrids and other observations were beginning to trouble him.

The next year Gray wrote a lucid and penetrating positive evaluation of Alphonse De Candolle's two-volume Géographie botanique raisonnée, a pioneering work dealing with plant geography and distribution from a statistical perspective. Hooker had sneeringly dismissed the work. In A. Hunter Dupree's authoritative biography of Gray, he describes Gray's puzzlement at Hooker's response in these terms:

Although in the long view Gray's evaluation of the epoch-making nature of De Candolle's book was more justified than Hooker's sneers, [Gray was confused by his response, for] Hooker seemed to be talking with a more comprehensive theory definitely in mind, some reason for taking his position, which he did not divulge and which his friend [Gray] did not possess.²

Darwin, however, saw in both Gray's review of Hooker's book and in his comments on De Candolle's tome that Gray was troubled by some of the same empirical data that had been bothering him. In April 1855, Darwin wrote Gray to urge that Gray update his Manual of the Botany of the Northern United States first published in 1848, and especially to address the issue of the range of Alpine plants in the United States. Specifically, he said: "Now I would say it is your duty to generalise as far as you safely can from your as yet completed work."³

Behind this request was Darwin's desire to test his impression that Gray could make a good ally. Gray passed the test, and finally, in July 1857, Darwin let Gray in on his theory of the transmutation of species. Gray was never an uncritical supporter, and there are many evidences in the correspondence between these two scientists that Gray was willing to challenge Darwin and disagree with some of his conclusions. Nevertheless, Gray saw the importance of Darwin's work and the ways in which it provided answers to the troublesome issues that he had confronted in his own botanical efforts.

Gray responds to Darwin's theory

After considerable interchange--one might even say debate--among Gray, Darwin, and Hooker, Gray wrote to Hooker in October 1859 (one month before the publication of On the Origin of Species) saying that he had absolutely no problem with cognate species arising by variation. He did, however, raise a concern that would be the source of much future discussion. He wondered about Darwin's "carry[ing] out this view to its ultimate and legitimate results,--how [do] you connect the philosophy of religion with the philosophy of your science." He added: "I should feel uneasy if I could not connect them into a consistent whole--i.e., fundamental principles of science should not be in conflict."⁴

When Origins was published, Gray wrote a clear, positive, yet critical review in The American Journal of Science. Aware of mounting religious opposition, he ended his review by arguing that whereas one could use Darwin's theory in support of an atheistic view of Nature, one could use any scientific theory in that way. He wrote: "The theory of gravitation and ... the nebular hypothesis assume a universal and ultimate physical cause, from which the effects in nature must necessarily have resulted."⁵ He did not see the physicists and astronomers who adopted Newton's theories as atheists or pantheists, though Leibniz earlier had raised such reservations. And a similar situation existed with the origin of species by natural selection. Darwin, Gray continued: "merely takes up a particular, proximate cause, or set of such causes, from which, it is argued, the present diversity of species has or may have contingently resulted. The author does not say necessarily resulted."⁶

This far Gray could go with Darwin. But there was a point at which he parted company, and that was the fortuitous randomness of the process that Darwin's theory seemed to imply.

In part 2, Dr. Miles describes Darwin's struggle with the problem of natural evil and design in nature.

Notes

1. Cited in A. Hunter Dupree, Asa Gray: American Botanist, Friend of Darwin (Baltimore: The Johns Hopkins Press, 1959), 151. 2. Ibid., 236.
3. Charles Darwin, More Letters of Charles Darwin, ed. Francis Darwin, (New York: D. Appleton and Company, 1903), 252.
4. Dupree, Asa Gray, 266.
5. Asa Gray, "The Origin of Species" in Darwiniana (Cambridge, MA: The Belknap Press of Harvard University, 1963), 44.
6. Ibid.

Darwin’s finches are some of the most visible and recognizable symbols of evolution in the world today. Biology textbooks feature them prominently, and the National Academy of Sciences has enshrined them in the entrance of their headquarters in Washington, DC. Surely the finches that Darwin collected on the Galápagos islands were a central feature of his evolutionary theory, right?

Lobby of The National Academies Building. Courtesy of CPNAS. Photo by Robert Lautman

Actually, the Galápagos finches are never even mentioned in Darwin’s famous work On the Origin of Species. Nor do they appear in Darwin’s famous notebooks on “Transmutation of Species”, in which he formulated the idea of evolution by natural selection.¹ Even Darwin’s private diary of his voyage on the HMS Beagle only mentions the Galápagos finches briefly in passing.²

It was only in 1845, in the second edition of The Voyage of the Beagle, that Darwin included a tantalizing sentence about the Galápagos finches:

Seeing this gradation and diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends.³

However insightful this statement may have been, Darwin never published anything else about the Galápagos finches for the rest of his life. Nor did he publically present these birds as direct evidence for this theory of evolution.⁴

If these finches were so important to Darwin’s evolutionary theory, why did he remain silent about them? One of his comments in The Voyage of the Beagle provides us with a clue:

Unfortunately most of the specimens of the finch tribe were mingled together; but I have strong reasons to suspect that some of the species of the subgroup Geospiza are confined to separate islands.⁵

When Darwin was exploring the Galápagos himself in 1835, he had not formulated his theory of evolution yet, and thus he did know what data would be necessary to make definitive conclusions about finch evolution. In particular, he did not keep careful track of which of his specimens came from which islands. Moreover, as was customary among naturalists at that time, Darwin only collected a small number specimens—he brought home only 31 finches and 64 total birds from the Galápagos.⁶

Though Darwin sensed that these birds were truly special, he lacked sufficient evidence to reach any specific conclusions about their evolutionary origins. It would be up to the rest of the scientific community to carry out the necessary empirical research. Subsequent expeditions in 1868, 1891, 1897, and 1905 brought back thousands of Galápagos finch specimens, but instead of unlocking the mysteries of evolutionary theory, the Galápagos finches became a great enigma.⁷

A century after Darwin's voyage, scientists still struggled to explain the staggering variety of finches on this tiny, remote archipelago. By the mid-1930’s, British Museum ornithologist Percy Lowe argued that the finches presented a "biological problem of first class importance", and he told the British Association for the Advancement of Science that the finches displayed a "bewildering diversity, intergradation, and distribution".⁸ Who would be up to the challenge of making sense of such tremendous biological complexity? It was David Lack.

David Lack

Ornithologist David Lack

David Lack had an exceptionally keen eye for bird-watching, and he possessed a passion to match it. By age 15, he had already observed 100 distinct species of birds, and before entering college, authored his first scientific paper. At Cambridge University in the early 1930’s, Lack was disappointed to find that his zoology professors taught “nothing about evolution, ecology, behavior or genetics, and of course nothing about birds.”⁹ In fact, at that time, there were only two professional ornithologists in all of Britain!

Thus David Lack took it upon himself to create his own learning opportunities. As an undergraduate, he became the president of the Cambridge Ornithological Club, traveled to Greenland for a bird-watching expedition, and cultivated a relationship with the prominent biologist Julian Huxley (grandson of Thomas Henry Huxley). Huxley was an inspiring mentor and encouraged Lack to expand his research further by studying tropical birds.¹⁰ Following this advice, Lack embarked on a research trip to Tanzania in the summer of 1934, but his greatest adventure was yet to come.

In 1937, Lack became fascinated by the scientific mysteries surrounding the Galápagos finches. But in order to study their behavior, Lack would need to travel to remote islands halfway around the world. How could he possibly get there? Once again, Julian Huxley was tremendously supportive and raised funds from two prominent scientific societies to pay for his expedition. After a long delay, David Lack and five companions finally set off on their journey.

Instead of residing in comfortable quarters aboard a royal naval ship, Lack’s group subsisted on a shoestring budget, traveled on commercial steamers, and stayed with local settlers. Their experience was definitely not a romantic tale of imperial expedition:

The Galápagos are interesting, but scarcely a residential paradise. The biological peculiarities are offset by an enervating climate, monotonous scenery, dense thorn scrub, cactus spines, loose sharp lava, food deficiencies, water shortage, black rats, fleas, jiggers, ants, mosquitoes, scorpions, Ecuadorian Indians of doubtful honesty, and dejected, disillusioned European settlers.¹¹

Whereas Charles Darwin spent only nineteen days on the shores of the Galápagos, Lack and his crew conducted more than five months of meticulous and exhausting study in the harsh climate. At that time, even the finches themselves provided little solace. Lack wrote,

Darwin’s finches are dull to look at, not only in their orderly ranks in museum trays, but also when they hop about the ground or perch in the trees of the Galápagos, making dull unmusical noises. Only the variety of their beaks and the number of their species excite attention.¹²

Large Cactus Finch on Española Island in the Galápagos Islands

The repetitive tedium requisite for important scientific discoveries is rarely discussed in public, and even today many bright-eyed science students become disillusioned by the painstaking work demanded by their Ph.D. programs. But one of the things that distinguishes great scientists is their unwavering commitment and tenacity in completing major projects. David Lack's efforts were not in vain:

"Despite his personal discomforts (or perhaps because of them), Lack did see something on the Galápagos that no one had ever seen before—natural selection at work among its finches through interspecies competition." ¹³

When the birds’ breeding season ended in 1939, Lack was ready to return to his home in England. But the captive finches that he had brought with him fared so badly on the voyage home that he detoured to San Francisco and put them in the care of the California Academy of Sciences. Turning this mishap into an opportunity, Lack stayed there for five additional months to study the Academy’s enormous collection of Galápagos finch specimens.¹⁴

To complete his systematic research, Lack then travelled across the United States to study the Galápagos finch collection housed at the American Museum in New York.¹⁵ Altogether, Lack examined more than 8000 specimens and specifically measured the length, width, and depth of all their beaks.¹⁶

Lack’s final obstacle was in getting his research published. Though he completed his academic manuscript “The Galápagos Finches—A Study in Variation” in 1940, paper shortages during World War II delayed its publication by the California Academy of Sciences until 1945. Were he only interested in making an original contribution to science, Lack could have stopped here and congratulated himself on a job well-done. However, his motivation sprung from a deeper source:

David Lack's drawing of 14 species of Galápagos finches, p. 19 of Darwin’s Finches

"I did not watch birds primarily for scientific reasons but for sheer enjoyment, and from the age of 15 onward returned day after day in a glow of excitement after seeing a new bird or a new habit." ¹⁷

Lack’s joyful fascination with the Galápagos finches inspired him to continue developing his conclusions long after returning from his expedition. While waiting for his academic paper to be published, he began writing a book that would enable students and the general public to share his excitement about these remarkable birds and the evolutionary processes that shaped them.

First published in 1947, Lack’s book became tremendously influential. Before this time, biology textbooks had never even mentioned the Galápagos finches. But after David Lack’s study, the finches became a primary example of evolution by natural selection, specifically adaptive radiation. Not only did textbooks fully rely on Lack’s findings, they also followed his lead in calling them “Darwin’s finches”, the title of Lack’s famous book.¹⁸

Iconic Finches

What was it about these birds that made them such a prominent symbol of evolution? As Darwin himself pointed out, the numerous Galápagos finch populations each have distinctive beaks, and he speculated that they could have evolved from an ancestral species that came to the islands. But a complete picture of finch evolution would have to wait another hundred years, when David Lack arrived.

During his five months on the Galápagos, including both the rainy and dry seasons, Lack observed that these beak differences enable the finches to subsist on different kinds of food:

The beak differences between most of the genera and subgenera of Darwin's finches are clearly correlated with differences in feeding methods. This is well borne out by the heavy, finch-like beak of the seed-eating Geospiza, the long beak of the flower-probing Cactornis, the somewhat parrot-like beak of the leaf, bud, and fruit-eating Platyspiza, the woodpecker-like beak of the woodboring Catcospiza, and the warbler-like beaks of the insect-eating certhidea and Pinaroloxias.¹⁹

Lack's image of beak adaptations from Darwin’s Finches

Specializing in such different sources of food enables these finches to live in close proximity without directly competing with each other or driving populations to extinction. The fact that so many of these closely related finches are able to co-exist is a remarkable fact in itself. As Lack himself put it, “It is not only the origin, but also the persistence, of new species which require explanation.”²⁰

But it is also fascinating to consider how these birds got to be so different in the first place. How did a finch come to have a beak like a “parrot”, “woodpecker”, or “warbler”? The answer lies in the distinct characteristics of the Galápagos. Because the islands are so remote, no actual parrots, woodpeckers, or warblers ever settled on it. In the absence of these species, the Galápagos finches were able to adopt feeding habits and forms that they would never have taken on a large continent full of other birds competing for food. The isolation of these islands offered just the right conditions for us to see living examples of adaptive radiation.²¹

Conclusion

Considering the immense popularity of the Galápagos finches, it is quite surprising to learn that Charles Darwin himself had so little to say about them. In fact, it was actually David Lack, one century later, who conducted the critical research that immortalized the finches in biology textbooks and popular lore. By naming his landmark book Darwin’s Finches,²² Lack paid homage to the man whose voyage on the HMS Beagle helped transform the study of natural history. But at the same time, Lack also obscured the fact that evolutionary biology is an enterprise conducted by a large community of brilliant scholars, not just the product of one man’s efforts.

This tendency to immortalize “great men of science” has also led many people to refer to modern evolutionary theory as Darwinism, despite the fact that it has substantially changed and developed over the past 150 years. It is important to give credit where credit is due, and if that’s the case, we should seriously reconsider how we refer to the Galapagos finches. Evolutionary biologist Dolph Schluter, who studied the finches several decades after David Lack, had this to say:

I find Lack's intuition really stunning given how little information he had. He's my hero actually… They should be called Lack's finches.²³

In the second part of this series, we’ll explore the fact that David Lack, in addition to being a world-renowned evolutionary biologist, was also a devout Christian. His study of evolutionary theory did not cause him to lose his faith; in fact, he actually converted to Christianity after completing his Galápagos finch research.

For Discussion

Further Reading

• Grant, Peter R.; Grant, B. Rosemary. How and Why Species Multiply: The Radiation of Darwin's Finches, Princeton University Press, 2008.
• Sulloway, Frank J. (Spring 1982), "Darwin and His Finches: The Evolution of a Legend" (PDF), Journal of the History of Biology 15 (1): 1–53.
• Weiner, Jonathon. The Beak of the Finch: A Story of Evolution in Our Time. Vintage Books, 1995.

Notes

1. Sulloway, F. (1983). "Darwin and his finches: The evolution of a legend." Journal of the history of biology 15(1): 32. Darwin’s notebooks on transmutation mentioned Galapagos tortoises and mockingbirds, not finches.
2. Lack, David. Darwin’s Finches. Cambridge University Press, 1947: 9. Confirmed by Sulloway (1983), p5.
3. Darwin, Charles. Journal of researches into the natural history and geology of the countries visited during the voyage of H.M.S. Beagle round the world. London: John Murray. 2d ed. 1845: 379-80. This edition of the book also contained the drawings of four different finches that have become enshrined in biology textbooks and on the walls of the National Academy of Sciences in Washington, DC.
4. Sulloway, p35. Sulloway points out that the first published evolutionary account of the Galapagos finches was not until 1876, by Osbert Salvin: "On the Avifauna of the Galapagos Archipelago." Trans. Zool. Soc. London, 9:447-51.
5. Darwin (1845), p395.
6. Sulloway, p40.
7. Sulloway, p40.
8. Larson, E. J. Evolution's Workshop: God and Science on the Galapagos Islands. New York, Basic Books, 2001: 166-67.
9. Lack, David. (1973) “My life as an amateur ornithologist.” Ibis: 424.
10. Lack (1973), 425-27.
11. Lack (1947), p1.
12. Lack (1947), p11.
13. Larson, 167-68.
14. The California Academy of Sciences sponsored an expedition to the Galapagos in 1905-06 and collected nearly 9000 Galapagos finch specimens (Sulloway, p40).
15. In New York, Lack roomed with the curator of the finch collection—German émigré zoologist Ernst Mayr. By developing this relationship, Lack had close ties with two of the biggest figures in the neo-Darwinian synthesis, Julian Huxley and Ernst Mayr (Larson, 168).
16. Larson, p168.
17. Lack (1973), p424.
18. Larson, p198.
19. Lack (1947), p60.
20. Lack (1947), p158.
21. See Lack’s concluding chapter on “Adaptive Radiation”, pp146-159 of Darwin’s Finches (1947).
22. British ornithologist Percy Lowe originally proposed the name “Darwin’s finches” in 1935, but the name did not catch on until Lack used it in his book. See P.R. Lowe, (1936) "The Finches of the Galapagos in Relation to Darwin's Conception of Species." Ibis, 13th ser., 6:310-321. (Cited in Larson, p287)
23. Schluter, in an interview with Edward Larson, 16 March 2000.

Eugene Dubois

13 years before, in 1877, Dubois had arrived in Amsterdam to study medicine, but always harboring a desire to study the ancestry of modern humans. So, after four years at the University there, he accepted an invitation to go to the University of Utrecht to study comparative anatomy and devote himself to the latest thinking about the origins of the human species. It was during his time at Utrecht (from 1881 to 1887) that Dubois became enamored of Haeckel’s views on human origins, which differed from those of Darwin. While Darwin argued that humans had evolved in Africa, the region in which our closest living relatives—the chimpanzees and gorillas—still live, Haeckel believed that the origins of humanity lay in East Asia. This was so, he believed, because of his own observations of gibbons that walk bipedally when on the ground.

Haeckel also believed that there had once been a large landmass called Lemuria between the continents of Africa and Asia. In his view, Lemuria had since become submerged, leaving the modern islands of Madagascar and the East Indies as its only remains. The idea of submerged continents was not unusual for the late 19th-century, as people struggled to understand the character of biological diversity present in the world and why there were such striking similarities between animals that were geographically dispersed. The geographical distribution of marsupial fossils in South America and Australia is an example of this sort of problem, and one that was not solved until the second half of the 20th century when continental drift reconstructions suggested that ancient marsupials had used Antarctica as a conduit between the other two continents. Not only did such theories make sense of modern distributions, they were confirmed with later discoveries of marsupial fossils in Antarctica.

In any case, in 1888 Dubois joined the army and set out for the Dutch East Indies to pursue his ideas. For the next two years, he would comb Sumatra attempting to locate the hominin remains that Haeckel promised would be there. In hindsight, what Dubois was attempting was something that had never been done before: discovery of hominin material through the tools of archaeological excavation. Up to this point, all of the human fossils had been found on the surface, eroding out of the side of a bank, or as a result of farming. It had not occurred to anyone to go looking for human ancestors.

Now, with his supply of prison workers dwindling due to desertion and fever, he had almost run out of options and was on the verge of failure. Using almost all of his remaining resources, he decided to abandon his excavations on Sumatra and turn to the nearby island of Java. Emboldened by the fact that early modern human fossils had been discovered there (at Wadjak), he arrived and settled in at Trinil, on the banks of the Solo River, in 1890.

Figure 1: Dubois' Pithecanthropus erectus

The very next year, Dubois’ long-standing efforts were finally rewarded, first with the discovery of a skullcap (calvaria) of a hominin cranium, and then with an intact femur (Figure 1). Judging by what he knew of cranial anatomy, Dubois estimated that the skull would have been approximately 900 cubic centimeters (cc) in volume, placing it below even the lowest threshold of modern humans. Further, he noticed that it was not like modern humans in shape, being too long and low. He concluded that it showed “evidence of a form intermediate between man and the anthropoid apes” (Dubois, 1896). Dubois envisioned a sequence of forms in which the gibbon gave rise to a form of chimpanzee called Anthropopithecus sivalensis, which then gave rise to the form represented by the Trinil remains, after which Homo sapiens arose (Turner, 1895).

Dubois spent the next twenty years on the road with his find, trying to drum up support for its place in human prehistory. As with Raymond Dart’s discovery of the first australopithecine thirty-three years later, Dubois did not receive a warm reception. Most critics simply said that he had gotten it wrong and that the femur did not belong to the same individual as the obviously-primitive skull cap. Some of the criticism Dubois suffered could have been mitigated had he been more open to sharing the Trinil materials; but, instead, he allowed very little access to the bones, so that very few people knew exactly what they looked like. Adding to Dubois’s credibility problems was the 1911 “discovery” of Piltdown. This intentional hoax turned the paleoanthropology world on its head for forty years, sending researchers down innumerable rabbit holes. As I noted in a previous post, the Piltdown remains made all of the other hominin finds appear too “ape-like” to be on the road to humanity and informed many opinions about finds such as those from Trinil.

On the other hand, some critics of Dubois’ new hominin claim were vicious, and questioned both his academic abilities and his judgment (Shipman & Storm, 2002)—in addition to the interpretation of the find itself. It was in reference to Dubois’ work that the term “Missing Link” was first used with reference to a particular human fossil, originating with Charles Lyell (1863) and describing palaeontological gaps. And ironically, it was in one of the most stinging criticisms of Dubois’ work that the name that would eventually stick was first used: “Homo erectus.” Eventually, many other finds in the same general area and across Southeast Asia demonstrated that what Dubois had found was a real, previously-unknown hominin form, and the first to colonize the Asian continent and the islands leading off towards Oceania.

Homo erectus across South East Asia:

Figure 2: Sangiran 17

Sangiran

The earliest point at which Homo erectus appears to have begun to colonize the greater East Asian region is around 1.8 million years ago, represented first by the partial child’s skull found at the site of Modjokerto, and then, at around 1.66 million years ago, at the site of Sangiran, in Trinil, where Dubois had made his landmark discovery. This site was rich, yielding the remains of many crania, perhaps best represented by Sangiran 17 (Figure 2), an almost complete skull.

The material from the Sangiran site is very diverse morphologically, with some crania having capacities of as little as 700 to 800 cc, and other, larger heads with volumes in the range of 1000 cc. As with the late Homo ergaster finds from Africa, the remains from Sangiran yielded crania that were still widest at their bases, possessing large brow ridges. Some have thick cranial bones and are very robust (Sangiran 4), while others are very gracile (Sangiran 31). What this variation means is not clear, but most workers believe it represents a very diverse diachronic population (that is, one group living and moving around over a long period) rather than separate species inhabiting the area. The Sangiran site yielded fossil material in an almost continuous succession from approximately 1.66 million years ago to less than 800,000 years ago.

Because the area of the excavations—the Sangiran Dome—is a volcanic deposit, the layers have been securely dated by the ⁴⁰Ar/³⁹Ar method, although questions remain about the historical sequence and distribution of other animals that lived there through the ages (its faunal succession). The problem is that many of the fossils were not found in context, and relating them directly to the stratigraphy is tenuous. Despite this, most workers are comfortable with the earliest hominins in the region being at least 1.5 million years old.

One of the things hampering workers in this region is the comparative paucity of recovered stone tools. Those that have been found suggest a technological stage similar to the late Oldowan design, equivalent to that being created by the Homo ergaster populations inhabiting the area of Dmanisi and East Africa. Unfortunately, none of the tools have been associated with the hominins directly so it is not exactly clear who made them.

Figure 3: Sambungmacan 3

Sambungmacan

Another major find from the area where Dubois brought Homo erectus to light is the cranium from the site of Sambungmachan. This skull was reportedly found in 1977 but was then illegally sold to the antiquities market, where is spent considerable time in different collections before being “rediscovered” in 1998—in a New York nature curio shop called Maxilla and Mandible, Inc. (Delson et al., 2001). This was an almost-complete calvaria (Figure 3), with only part of the base missing. It is equivalent in size to the fossils from Sangiran, with a cranial capacity of around 1000 cc. It has a large brow ridge extending all of the way across the top of the eyes, a long, low cranium with a sloping forehead and a maximum width near the cranial base—all features that are also characteristic of the late African H. ergaster and Sangiran crania. Although we will never know exactly how old this cranium is, its morphology is consistent with that of the material from Sangiran.

Figure 4: Ngandong 6

Ngandong

Later in time, but also located on the Solo River, is the site of Ngandong, excavated by Oppenoorth in the early 1930s. At this site, fourteen calvaria have been discovered, all of which show advanced Homo erectus characteristics: long and low in shape, with thick-bones and a distinctive brow-ridge. (Figure 4). As with the other Indonesian finds, dating the Ngandong material has been problematic. The deposits at the site were originally thought to be around 100,000 years old, but this interpretation was turned on its head in 1996, when Swisher and colleagues claimed that the deposits were no older than between 27,000 and 53,000 years old (Swisher et al., 1996). These age estimations were made on the associated fauna, however, and as Rainer Grün and the late Alan Thorne pointed out, the faunal material does not match the skulls either in color or in texture and is likely not from the same time. Recently, Swisher and colleagues revisited the dating of the site and derived internally-consistent dates of at least 143,000 years before the present (Indriati et al., 2011). As with the Trinil remains, however, there are no associated stone tools.

Homo erectus in China

The Chinese Homo erectus material is very widely scattered and working in the region has presented many difficulties for researchers in terms of transport, language barriers and funding. Consequently, we know less about this region and its previous inhabitants than we do about most other areas of the Old World. Although there are between ten and fifteen sites that have yielded Homo erectus material, I will only touch on the most important ones.

Lantian:

Figure 5: Lantian

In the early 1960s, a cranium and mandible were found in the cave of Lantian, Shaanxi province, whose characteristics matched other remains from China designated as Homo erectus. Paleomagnetic dating has yielded a date no earlier than 1.15 million years ago for the skull, with the consensus being that it is around 800,000 years old. A date of approximately 650,000 years before the present was derived for the mandible. The cranium is heavily encrusted and suffered from postmortem deformation (Figure 5). When reconstituted, it was found to have a capacity of around 780 cc (low for Homo erectus) and the bones on the sides of the head are the thickest yet recorded. At this site some flake tools, mammal remains, and an ash deposit were all recovered, suggesting hunting and control of fire.

Figure 5: Hexian

Hexian

Another almost-complete calvaria was found at Longtandong cave in the province of Hé Xiàn, dated to between 400,000 and 500,000 years ago. This find exemplifies typical Homo erectus in many ways in that it is long and low, with heavy muscle markings toward the base and the rear of the skull (Figure 6). The cranial capacity is around 1000 cc, a third-again greater than that of the Lantian calvaria. Its cranial shape is very similar to those found in Southeast Asia, suggesting that it straddles the Southeast Asian and Chinese boundary.

While both Lantian and Hexian were significant finds, another site in China boasted the single largest collection of Homo erectus fossils ever found at one site, as well as presenting one of the greatest mysteries in paleoanthropology. Tomorrow, in the conclusion of our look at Homo erectus in Asia, we’ll peer into the Zhoukoudian caves and consider how this species fits into the lineage of man.

There are two opposite errors which need to be countered about the fossil record: 1) that it is so incomplete as to be of no value in interpreting patterns and trends in the history of life, and 2) that it is so good that we should expect a relatively complete record of the details of evolutionary transitions within all or most lineages.

What then is the quality of the fossil record? It can be confidently stated that only a very small fraction of the species that once lived on Earth have been preserved in the rock record and subsequently discovered and described by science.

There is an entire field of scientific research referred to as "taphonomy" -- literally, "the study of death." Taphonomic research includes investigating those processes active from the time of death of an organism until its final burial by sediment. These processes include decomposition, scavenging, mechanical destruction, transportation, and chemical dissolution and alteration. The ways in which the remains of organisms are subsequently mechanically and chemically altered after burial are also examined -- including the various processes of fossilization. Burial and "fossilization" of an organism's remains in no way guarantees its ultimate preservation as a fossil. Processes such as dissolution and recrystallization can remove all record of fossils from the rock. What we collect as fossils are thus the "lucky" organisms that have avoided the wide spectrum of destructive pre- and post-depositional processes arrayed against them.

Soft-bodied organisms, and organisms with non-mineralized skeletons have very little chance of preservation under most environmental conditions. Until the Cambrian nearly all organisms were soft-bodied, and even today the majority of species in marine communities are soft-bodied. The discovery of new soft-bodied fossil localities is always met with great enthusiasm. These localities typically turn up new species with unusual morphologies, and new higher taxa can be erected on the basis of a few specimens! Such localities are also erratically and widely spaced geographically and in geologic time.

Even those organisms with preservable hard parts are unlikely to be preserved under "normal" conditions. Studies of the fate of clam shells in shallow coastal waters reveal that shells are rapidly destroyed by scavenging, boring, chemical dissolution and breakage. Occasional burial during major storm events is one process that favors the incorporation of shells into the sedimentary record, and their ultimate preservation as fossils. Getting terrestrial vertebrate material into the fossil record is even more difficult. The terrestrial environment is a very destructive one: with decomposition and scavenging together with physical and chemical destruction by weathering.

The potential for fossil preservation varies dramatically from environment to environment. Preservation is enhanced under conditions that limit destructive physical and biological processes. Thus marine and fresh water environments with low oxygen levels, high salinities, or relatively high rates of sediment deposition favor preservation. Similarly, in some environments biochemical conditions can favor the early mineralization of skeletons and even soft tissues by a variety of compounds (eg. carbonate, silica, pyrite, and phosphate). The likelihood of preservation is thus highly variable. As a result, the fossil record is biased toward sampling the biota of certain types of environments, and against sampling the biota of others.

In addition to these preservational biases, the erosion, deformation and metamorphism of originally fossiliferous sedimentary rock have eliminated significant portions of the fossil record over geologic time. Furthermore, much of the fossil-bearing sedimentary record is hidden in the subsurface, or located in poorly accessible or little studied geographic areas. For these reasons, of those once-living species actually preserved in the fossil record, only a small portion have been discovered and described by science. However, there is also the promise of continued new and important discovery.

The forces arrayed against fossil preservation also guarantee that the earliest fossils known for a given animal group will always date to some time after that group first evolved. The fossil record always provides only minimum ages for the first appearance of organisms.

Because of the biases of the fossil record, the most abundant and geographically widespread species of hardpart-bearing organisms would tend to be best represented. Also, short-lived species that belonged to rapidly evolving lines of descent are less likely to be preserved than long-lived stable species. Because evolutionary change is probably most rapid within small isolated populations, a detailed species-by-species record of such evolutionary transitions is unlikely to be preserved. Furthermore, capturing such evolutionary events in the fossil record requires the fortuitous sampling of the particular geographic locality where the changes occurred.

Using the model of a branching tree of life, the expectation is for the preservation of isolated branches on an originally very bushy evolutionary tree. A few of these branches (lines of descent) would be fairly complete, while most are reconstructed with only very fragmentary evidence. As a result, the large-scale patterns of evolutionary history can generally be better discerned than the population-by-population or species-by-species transitions. Evolutionary trends over longer periods of time and across greater anatomical transitions can be followed by reconstructing the sequences in which anatomical features were acquired within an evolving branch of the tree of life.

I ask the question, “Why is the universe so special?” Now scientists don’t like things to be special; we like things to be general, and our natural anticipation would have been that the universe is just a common or garden specimen of what a universe might be like.

But we’ve come to understand a lot about the history of the universe. We know that our universe started 13.7 billion years ago, and it started extremely simple, just an almost uniformly expanding ball of energy, about the simplest physical system you could possibly think about. But a world that started so simple has of course become rich and complex. With you and me, in fact, the most remarkable and complex consequences are its history, at least of which we are aware. The human brain is far and away the most complicated physical system we have ever encountered anywhere in our exploration of the universe.

That fact itself might suggest that something has been going on in cosmic history rather than just one thing after another. But we’ve also come to understand many of the processes by which this rich fruitfulness has come to birth. As we’ve come to understand these, we’ve come to see that though these processes are of course evolving processes, they took long periods of time – the universe was 10 billion years old before any form of life appeared in it, at least as far as we know anyway – and life of our complexity only appeared yesterday.

Nevertheless, the universe is pregnant with life, pregnant with the possibility of life, essentially from the beginning onwards. By which I mean the given laws of nature had to take a very specific, very finely tuned form, if the universe was to have so fruitful a history.

That’s a very remarkable discovery, and let me give you some examples of why we believe that. If you’re going to have a fruitful universe, one of the first things you have to get right is that you have to have the right stars in the universe. The stars are going to have a very important role to play. First of all, you must have some stars that are going to be very long lived, live for billions of years, steadily burning, steadily producing energy which will enable the development of life on one of the encircling planets. We understand what makes stars burn in that sort of way very well, and it depends on a delicate balance between the strength of gravity and the strength of electromagnetism. Electromagnetism is the force that holds matter together. The seats on which you are sitting are held together by electromagnetism and in fact you are held together by electromagnetism.

If you alter that balance a little bit in one direction the stars will begin to burn intensely, furiously, just pouring out energy and they will only live a few million years rather than a few billion years. If you move it a little bit in the other direction they will burn so slowly they will be brown stars and they will not produce enough energy to fuel the development of life. So you have to have a very delicate finely tuned balance between the strength of gravity and the strength of electromagnetic forces in a fruitful universe.

Remember, science takes the laws of nature, takes the given strengths of gravity, the given strength of electromagnetism, uses that to explain processes in the world, how things happen, but it doesn’t explain where those laws of nature come from. They are just brute facts as far as science is concerned.

And the stars have another absolutely indispensible role to play. The stars are the place where the heavier elements essential for life are made in the interior nuclear furnaces. There are many elements that are necessary for life, of which carbon is perhaps the most essential. Carbon is the basis of the long chain molecules, which are the biochemical basis of life. The early universe only makes the simplest elements; it makes hydrogen and helium and it makes no carbon at all. Carbon only begins to be made when the universe, which started uniform, begins to condense and become lumpy and grainy with stars and galaxies. As the stars condense they heat up, nuclear processes begin again in their interiors. And it’s those nuclear processes in the stars that make carbon and the heavier elements. Every atom of carbon in your body was once inside a star. We are people of stardust made in the ashes of dead stars.

And that’s a very beautiful process that takes place in that sort of way. And one of the great triumphs of astrophysics and the second half of the 20th century was to unravel that process. One of the people who did some of the most important work on that was a senior colleague of mine in Cambridge called Fred Hoyle. And they were trying to figure out how to make carbon. They got helium, and if you can make three helium nuclei stick together that will produce carbon, but when you have something as small as a nucleus it is impossible to get three to stick together at one time, they’re just too small.

Ok, so let’s do it step by step. Stick two together gives you berylium. Helium 4 gives you beryllium-8, hope it stays around for a bit, another helium comes along, attaches itself, and bingo, you’ve got carbon-12. That’s the obvious thing to think about but it doesn’t work in the obvious way, and the reason it doesn’t work in the obvious way is that beryllium-8 is terribly unstable. It doesn’t oblige you by staying around long enough to catch that third helium, at least in an ordinary, straightforward way.

But Fred realized that it would be just possible for this to happen if there was a very large enhancement effect, in the trade we call it resonance, occurring in carbon at just the right energy, it has to be the right energy, which would enable that attachment process to catch that third helium much much more quickly that you might have thought, in fact so quickly that some of them would get caught before the beryllium-8 disappeared. It was a very good idea, and he must have felt pretty pleased with himself and he went off to just check in the nuclear data tables of this particular resonance’s energy levels, and it wasn’t in the tables, but he knew it must be there, he’s carbon based life like you and me.

So he rang up some friends in the States, a father and son team who were good experimentalists and he said, “Look, you missed something. There’s a resonance and energy level in carbon that you haven’t spotted, and I’ll tell you exactly where to look for it. I know exactly where this energy has got to be. You go look for it.” And they said, “No, no, we don’t want to do that, we have more interesting things to do.” But Fred was very determined and he bullied them into looking for it and they found it.

Now that’s a wonderful achievement, to predict an energy level in carbon on the basis of how it might have been made in the stars is a fantastic scientific achievement. But it’s more than that. Fred had a lifetime conviction of atheism, realized of course that if the laws of physics had been just a little bit different that resonance wouldn’t have been there, and the possibility of carbon-based life is too significant for it just to be a happy accident in his view, so he says in a Yorkshire accent that is beyond my power to imitate, he said that the universe is a put-up job. Fred didn’t like the word God, and so he said some Intelligent, capital “I” Intelligence, must have monkied with the laws of nature to make carbon production possible. What that could possibly be I don’t know, but the more sensible thing to say is that creation is ordained, that the laws of nature would be such, as to enable the fruitfulness of carbon-based life.

We’ll come back to evaluating that possibility in a minute, but before we do, let me give you two other examples of how specific, how special, our universe has to be for us to be able to be here today to think about. We live in a universe that is immensely big, beyond our powers to imagine really. There are a hundred thousand million stars in our galaxy in the Milky Way, of which our sun is just a common or garden specimen, and there are about a hundred thousand million galaxies in the observable universe, of which our Milky Way is a pretty common or garden specimen. So we live in a world that is unimaginably vast, and sometimes we might feel upset by that and think, “What could be the significance of us who are simply inhabitants of a speck of cosmic dust, as you might say, in this vast, vast universe?”

Nevertheless, if all those stars were not there, we would not be here to be upset at the thought of them. Because there is a direct connection between how big a universe is and how long it lasts, and a universe that is significantly smaller than our universe would not have been able to last the 14 billion years, which is the necessary time to produce beings of our complexity. So that’s another condition of the world that has to be right for human beings, or something like human beings, to be a possibility.

One final example, which is the finest tuning of all: quantum theory suggests that there should be an energy attached to space itself. In quantum theory the vacuum, so called empty space, is not just a void. There are things called vacuum fluctuations which occur in a continual sort of seething mass of things coming into being and going out of being all the time. So while there is nothing there that doesn’t mean there is nothing happening. That may sound strange and paradoxical but believe me that’s what quantum theory implies. And of course these happenings, these fluctuations, generate a certain amount of energy, we call it “zero point energy”, and that energy is spread out over the whole of space. So we expect there to be energy associated with space.

And just recently the astronomers have discovered something called dark energy which is driving the expansion of the universe, which is just such an energy associated with space. Well that’s very good, you might say. However, when we estimate, just from thinking about quantum theory, how much energy there should be in space it turns out to be a fantastically large amount, and when we see the amount of energy there actually is per volume in space, it turns out to be very, very small in relation to that expected size. In fact, it turns out to be smaller by a factor of 10^-120. That means by a factor of 1 over 1 followed by 120 zeros. You don’t have to be a great mathematician to see that’s a fantastically small number. So some fantastic cancellation has taken place to turn that big number into the tiny number that we actually observe, and if it hadn’t taken place we wouldn’t be here to observe it because significantly higher energy would simply have blown the whole show apart too fast for anything interesting to happen. That’s the finest tuning that we know in the universe: one part in 10¹²⁰.

So we live in a world that is very remarkably finely tuned, and we have to consider that. And all scientists would agree about what I have been telling you; this is non-contentious. Where the contention comes in is what we might make of that, what is the further significance of it.

In the conclusion to Dr. Polkinghorne’s lecture, he looks at two explanations for the "fine-tuning" principle -- the multiverse theory and the existence of a divine intelligence -- and explains why natural theology alone is not sufficient to make the case for a God who interacts and cares for his creation. To make the case for theism, he argues, we need revelation, God's self-disclosure. This is manifest in various ways, including that which we experience personally, including ethics and aesthetics.

Design arguments have been around forever and expressed in various ways. Most of them fall into what we call natural theology, which is the process of inferring something about the existence and nature of God by the inspection of nature. The story of creation in Genesis launches the discussion in the Judeo-Christian tradition when it speaks of God ordering nature and driving back chaos. On the fourth day “God created the sun, moon, and the stars to give light to the earth and to govern and separate the day and the night. These would also serve as signs to mark seasons, days, and years.” All this suggests design and purpose. Job speaks of God making “water drops evaporate” so the clouds can “shower abundantly on mankind.” (Job 36:27-28 HCSB). The psalmist expresses awe at the grandeur of the night sky but remarkably does not comment on the grandeur of his own existence:

When I observe Your heavens, the work of Your fingers, . . . what is man that You remember him? (Psalm 8:3-4 HCSB)

In the New Testament, Paul speaks of the created order testifying clearly to the reality of God, arguing that, “the invisible things of [God] from the creation of the world are clearly seen, being understood by the things that are made” (Romans 1:20 KJV). Biblical scholars have interpreted this to mean that an open-minded seeker can infer the existence of God by studying the creation. As theologians reflected on the nature of the creation these arguments were repeated and refined. Augustine in the fourth century, Thomas Aquinas in the thirteenth century, Luther and Calvin at the time of the Reformation in the sixteenth century—all were understandably convinced that the world had a grand design that was readily discernable. After all, nobody had any other explanation for why birds were adapted to fly, fish to swim and constellations to mark the seasons.

By the time we get to Isaac Newton in the latter part of the seventeenth century, we have the first carefully constructed scientific arguments. Newton, as we learned in high school, explained how gravity from the sun keeps the planets in their orbits. This explanation replaced previous medieval explanations that included the possibility that the planets moved because angels pushed on them. (It also replaced Galileo’s explanation that they moved because of a “circular inertia,” which turned out to be as much a fantasy as the pushing angels.) But Newton’s theory didn’t explain why the planets all go around the sun in the same direction and in almost the same plane. In fact Newton could not imagine any natural process that could produce such elegant design, so he argued that God must be the explanation.

About two centuries later the most famous design argument was developed by William Paley whose Natural Theology Darwin read voraciously as a young scientist. “Suppose I had found a watch upon the ground,” asked Paley, “and it should be inquired how the watch happened to be in that place. . . . [W]hen we come to inspect the watch, we perceive . . . that its several parts are framed and put together for a purpose. . . . [T]he inference, we think, is inevitable, that the watch must have had a maker.” Paley goes on to compare the watch to an eye, arguing that if a watch implies a watchmaker, then an eye implies an eye-maker. The eye-maker, of course, can only be God.

Newton’s argument about the planets and Paley’s about the watch have the same logical form: We find something in nature that appears too ingeniously arranged to have been produced by known natural processes, so we infer that a Designer from outside the natural order—God— must be the source of the design. Their arguments differ, however, on the question of purpose. It was not clear to Newton or anyone of his day exactly why the planets needed to be going about in the orderly way they were observed. If the order was indeed provided by God, no explanation for it could be discerned other than the creation of order for the sake of order. In contrast, the designs that Paley highlighted were clearly purposeful. Our eye is remarkably designed for a purpose other than to elicit awe at its complexity. We see with our eyes. We don’t do anything with Neptune’s nice orbit, other than admire it.

Red Flags

Arguments that the universe is designed are complicated. We certainly live in a remarkable universe with many features that inspire awe. Many of those features connect in astonishing ways to the habitability of the universe. The psalmist’s wonder at the heavens has only grown stronger as we have learned more about those heavens. The universe certainly does not become ever more boring and bland as we come to understand it better.

But we also live in a world with earthquakes, plagues and tsunamis. Our sun will burn out at some point, incinerating the earth in the process. The prospects of securing our future by colonizing other planets seem remote. The long-term prognosis of the universe, by the cold logical lights of science, is not good. Its temperature will continuously drop as it expands for billions of years. Eventually there won’t be enough heat left for any form of life, and finally there won’t even be enough heat for atoms and molecules to interact. This sterile icy blackness is frightening to contemplate. No matter what we do as a species, we and our cultural achievements are destined to perish.

No simple overriding explanation that makes sense of everything comes into view as we learn more about the universe. And experience with past arguments raises red caution flags. For example, Newton’s design argument about the planets was an argument from ignorance that now bears the label “god of the gaps.” There was a gap in Newton’s explanation for the planets. He could explain why their orbits were elliptical and what kept them in their orbits. But he could not explain the uniformity of their orbits, so he invoked God as the explanation to plug this gap—hence the label for such arguments—god of the gaps.

A century after Newton, French physicist Pierre Simon de Laplace dispelled the mystery of the structure of the solar system. He showed that a better understanding of gravity and how solar systems originated could explain the things that Newton attributed to the direct action of God. Laplace’s work did not refute the existence of God, of course. But it did dismantle Newton’s argument that the planetary orbits must have been set up by God, thus eliminating an argument that some had been using to argue for God’s existence.

In a similar way, Darwin’s theory of evolution offers an explanation for the design that Paley marveled at in the eye. Scholars of Paley’s generation knew nothing of natural selection, mutations or genetics, so they could not imagine how nature might craft something so remarkable as an eye. Paley’s argument, like Newton’s, turns out to be another god of the gaps explanation that disappears with further scientific insights into the way the world works.

So this is the first red flag to note—design arguments are all-too-often based on gaps in our knowledge and will disappear when those gaps are filled.

The second red flag concerns the apparent purpose of any design. “Design” can point in many directions or no direction at all. The science museum in Boston has a grand contraption that does nothing except move balls around to no end. The only possible purpose is to impress a visitor with the juxtaposition of complex design and lack of purpose. There is likewise no significance to the patterns of the stars that we call constellations. The “design” of the Big Dipper is simply interesting. The fine-tuning of the universe for life, on the other hand, encourages us to wonder if life may be important in some way. But it does not specify which life forms are relevant and why. And we must note that some features of our world exhibiting a high level of design—like the AIDS virus or the poison of the rattlesnake—seem to have the purpose to destroy human life. If rattlesnakes could reflect on their existence, they could marvel at the carbon resonance that makes that existence possible.

A third red flag we must note is bad design. If marvelous design in the universe motivates reflection on the possibility that God created the world what do we do about the counterarguments? Consider asteroids. A gigantic asteroid struck the Yucatan Peninsula 65 million years ago and so disrupted the ecosystems and the atmosphere of the earth that the dinosaurs went extinct. Absolutely nothing prevents the same thing from happening again. We are protected today largely by the vastness of space and the structure of our solar system with large outer planets that “vacuum up” a lot of stuff that could hit the earth. These various protections make collisions of the sort that wiped out the dinosaurs unlikely. But they offer no guarantees. If the Goldilocks features of our universe are intended to make it habitable, then why does the universe also have anti-Goldilocks features?

Many such issues complicate the process of figuring out why the universe is the way it is. And as we have learned somewhat reluctantly in the last few centuries, the great explanatory power of science disappears entirely when questions of purpose enter the conversation. Science is quite extraordinary at telling us how the world is but quite unable to tell us why the world is like that. Science illuminates the remarkable features of our universe that make life possible, but it goes silent when we ask whether any particular life form is the reason why the universe is the way it is. That deeply religious question has to be explored somewhere else.

These challenges caution us against naively selecting—cherry-picking we call it—a few Goldilocks features of the universe, assuming the friendly design work is for our benefit, and jumping to the conclusion that everything points simply and unambiguously in the direction of God as Creator.

Since this post, and those that will follow it, depend on an accurate representation of the argument for irreducible complexity (IC), I will take some time to clarify exactly how Michael Behe, the biochemist and Intelligent Design (ID) proponent who has most extensively developed the IC argument, uses the term. For Behe, the argument for IC is a critique of gradual evolutionary processes, of the kind that Darwin saw as necessary for his theory to hold. When Behe introduces and defines IC in his book Darwin’s Black Box, he has a key quote from Darwin on gradualism explicitly in view:

Darwin knew that his theory of gradual evolution by natural selection carried a heavy burden: "If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down."

It is safe to say the most of the scientific skepticism about Darwinism in the past century has centered on this requirement… critics of Darwin have suspected that his criterion of failure had been met. But how can we be confident? What type of biological system could not be formed by “numerous, successive, slight modifications”?

Well, for starters, a system that is irreducibly complex. By irreducibly complex I mean a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning. An irreducibly complex system cannot be produced directly (that is, by continuously improving the initial function, which continues to work by the same mechanism) by slight, successive modifications of a precursor system, because any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional. An irreducibly complex biological system, if there is such a thing, would be a powerful challenge to Darwinian evolution. (Darwin’s Black Box, p. 39)

The definition of an IC system is thus straightforward: it is a matched group of components, where all the components are necessary for the function of the system. The necessity of each component can be demonstrated by attempting to remove it – if the system no longer works if even one component is removed, it is by definition IC. Since an IC system requires all the components to be present for its function, it is not possible for the system, in its current state, to have been produced directly from a non-functional precursor. If one grants this premise, it leaves two options: that the IC system was derived indirectly, from a system that is not IC, or that the system was assembled by fiat and thus represents the actions of a designer. Behe’s criterion for distinguishing between these choices is based on evaluating the probabilities of these competing options:

Even if a system is irreducibly complex (and thus cannot have been produced directly), however, one can not definitively rule out the possibility of an indirect, circuitous route. As the complexity of an interacting system increases, though, the likelihood of such an indirect route drops precipitously. And as the number of unexplained, irreducibly complex biological systems increases, our confidence that Darwin's criterion of failure has been met skyrockets toward the maximum that science allows. (Darwin’s Black Box, p. 40)

As we will examine in an upcoming post, Behe attempts to determine the precise limit of what evolutionary processes can (and cannot) achieve in a second book, The Edge of Evolution. For our present purposes, however, it is enough to note that the strength of the argument from IC depends on the perceived implausibility of the opposing explanation – that of an indirect evolutionary route that produces an IC system from a non-IC precursor system.

Building IC, one step at a time?

The presence of IC systems in biology as Behe has defined them is not contentious: there are many biological systems that cease to function when parts are removed. Indeed, the success of classical genetics in “dissecting” which genes are needed for certain functions largely rests on the ability to see some effect on function when a gene is removed from a system by mutation. What scientists dispute, however, is Behe’s claim that identifying IC systems is a hallmark of design. The evolutionary model for building IC is quite simple, and Behe has set it out as an option: an indirect route where non-essential parts are added to a system, and then over time the system comes to depend on those parts. We can diagram this model as follows:

The key to the model is that new parts can be added to a system, and that these parts are not essential when they are added. The resulting system is thus not IC, since it has parts that are not essential to its function, even if the new parts are advantageous in some way. If the new component is taken away at this stage, the system merely reverts to the precursor system. The second part of the model is that these intermediate, non-IC systems then may become IC if small changes make the new parts essential.

The addition of new, non-essential parts can be accomplished in several ways, such as a change in an existing protein that allows it to bind to a “precursor system”. More extreme would be the generation of a new protein that then adds to a precursor system as a non-essential component. Brand new genes, by definition, cannot be essential when they arise, since they arise in an organism that, up to that point, had no need of them. Looking to see if new genes then later become essential would be very good experimental support for the evolutionary model for how IC systems arise.

In practice, it takes a lot of scientific effort to tease out changes to an existing protein that allow it to become part of an intermediate system and then progress to an IC system, though we have examined one such example in a previous post. Looking for brand new genes, however, is much easier – and some recent work in several fruit fly species (Drosophila) has done just that.

The Young and the Restless

So, how to go about finding genes that are new? We have already discussed, in the context of duplicating an entire genome, how duplication of genes may lead to the two copies picking up new functions over time. While duplication may happen rarely at a whole-genome scale, small-scale duplication of small numbers of genes happens quite frequently as an error during cell division. At the time of the duplication, the two copies are the same, and therefore functionally equivalent. Over time, however, the two copies may become different and acquire distinct functions.

One way to look for genes that have arisen due to a recent duplication event is to compare the genomes of closely related species and look for genes that are present in one species but not another, or in a subset of related species. Duplicated genes will show up in a nested hierarchy, much like how pseudogenes appear in the same nested pattern, as we have discussed previously here.

The complete genome sequences for a number of fruit fly species are available, so researchers used this method of comparison to look for new genes that mostly arose “recently” (over the last 35 million years) within flies. Since the speciation times for the various fly species are known to a good approximation, the time of the various duplication events can be estimated as well.

Putting the argument for IC to the test

Using this method, researchers identified 195 recent, “young” genes that arose through duplication events. (Note: this finding, in and of itself, is problematic for the ID argument that significant amounts of new information cannot arise through evolutionary mechanisms). More problematic for the argument from IC, however, is that just less than one third of these new genes are now essential for development in the species that carry them. This fraction is approximately the same for “old” genes – about one third are essential for development.

The implications are easily grasped: many new genes have arisen through duplication, and a sizeable fraction are now part of IC systems. When they arose, they could not have been essential, but now they are emphatically so. As such, they must have been added to previous systems, and become IC over time. Moreover, this effect is not a rare, one-off event, but rather has been repeated time and again in recent evolutionary history.

In the next post in this series, we’ll delve into some of the details about how these new genes arose, and what sort of functions they have.

For further reading:

Behe, M.J. Darwin’s Black Box: the Biochemical Challenge to Evolution. Free Press, New York, 1996.

Behe, M.J. The Edge of Evolution: the Search for the Limits of Darwinism. Free Press, New York, 2007.

Chen, S., Zhang, Y, and Long, M (2010). New genes in Drosophila quickly become essential. Science 330; 1682-1685.

In the previous post in this series, we explored how evolution can force science into making predictions that seem counter-intuitive. For cetacean (whale) evolution, we saw that the preliminary lines of evidence (the fact that whales are vertebrates, and mammals, for instance) pointed to the prediction that modern whales are descended from four-limbed, land-dwelling ancestors. As we then noted:

Instantly this prediction raises a host of uncomfortable questions: where did their hind limbs go? How did they acquire a blowhole on the top of their heads when other mammals have two nostrils on the front of their faces? How did they transition to giving birth in the water? What happened to the teeth of the baleen whales? What happened to the hair characteristic of mammals? and so on. In some ways, evolutionary thinking about whales creates more difficulties than it appears to solve.

And yet, these difficulties are the stuff of science. If indeed our “educated guess” of terrestrial, tetrapod ancestry for whales is correct, the evidence will show that these transitions, challenging though they may seem, did indeed occur on the road to becoming “truly cetacean”.

We have already discussed hind limb and hair loss in whales, citing evidence from embryonic development in modern whales that shows how hair and hind limbs develop early in their embryogenesis, but then are lost at later stages. We now turn to one of the remaining questions: tooth loss in the lineage leading to modern toothless whales (order Mysticeti). To obtain their food these whales pass seawater through a baleen, a large sieve-like structure that filters out plankton, small fish and other food items. Some recent genetics sleuthing has investigated a portion of this riddle, and adds further details to the story of how the baleen whales came to be.

Evolution: A Theory with Bite

If indeed modern whales are descended from ancestral, four-limbed, terrestrial ancestors, then those ancestors, like mammals in general, had teeth. Modern toothed whales (order Odontoceti) have retained those teeth to the present day, but baleen whales have adopted a new way of life as filter-feeders. Researchers were curious to see if traces of a “toothed past” could be found in the genomes of modern baleen whales, so they went hunting for remnants of genes devoted to making teeth. Such defective gene remnants would be examples of pseudogenes, and we have discussed pseudogenes previously in this series. While pseudogenes in and of themselves are powerful evidence for evolution, pseudogenes that are “out of place” are especially so. One such example we have seen before is the human vitellogenin pseudogene, the remains of a gene used for yolk production in egg-laying organisms found in the exact location in the genome that evolution would predict for it. As mammals that receive embryonic nourishment through a placenta, we have no need of egg-yolk genes. Similarly, baleen whales have no need for genes responsible for making teeth, and finding the remnants of such genes would make a strong case for an evolutionary origin of baleen whales as the modified descendents of toothed whale ancestors.

Independent Lines of Evidence, but Contradictory Stories?

Some of the genes known to be used in all mammals for tooth formation were the obvious candidate genes to start with: the products of the ameloblastin, amelogenin, and enamelin genes are all used in the formation of tooth enamel, the hardest structure in the vertebrate skeleton. Researchers went looking for these genes in several Mysticete (i.e. toothless whale) species. The results showed that all the species studied did indeed have these three genes present as pseudogenes (and more specifically, as unitary pseudogenes, a special class of pseudogene we have discussed in detail previously). Finding these genes as pseudogenes in toothless whales was exactly what evolution predicted, but there was a catch: none of the mutations that removed the functions of these three genes were shared between different species, suggesting that these genes lost their function independently in the species studied. This finding was at odds with data from the fossil record, which suggested that teeth were lost only once, and early in the lineage leading to all modern toothless whales. So, the researchers seemed to have two lines of evidence that at face value contradicted each other. The fossil record suggested that tooth loss occurred once in the common ancestor of all toothless whales, but these three genes seemed to have been inactivated independently, several times over, suggesting that loss of teeth should be happening later in Mysticete evolution, and more than once.

One proposed explanation for the apparent discrepancy (among several put forward) was to predict that a fourth gene required for enamel formation was lost early in Mysticete evolution. The loss of any one gene necessary for forming enamel would be enough to prevent the process altogether. In this case, the loss of this fourth gene would prevent tooth enamel from forming, even though the genetic sequences of the other three enamel genes would still be intact. Once enamel function was lost, random mutations in the remaining enamel genes could then accumulate later in Mysticete evolution after speciation in this group was already underway. To test this hypothesis, the research group went hunting for other enamel genes in toothless whales.

Signature in the SINE

The smoking gun for tooth loss in Mysticetes turned out to be exactly what was predicted: a fourth gene, necessary for enamel production, and mutated with the same inactivating mutation in all modern toothless whales. The gene in question, named enamelysin, was destroyed when a mobile genetic element called a SINE transposon inserted into it, breaking it into two halves and removing its function:

The fact that the same SINE insertion mutation at an identical location is found in all modern Mysticete species indicates that this mutation happened once in a common ancestor and then was inherited by the entire group. Since this must have occurred early in the evolution of toothless whales in order to happen in the common ancestor of the entire group, the picture from the genetics and the fossil record match. Once again, findings in one discipline (in this case, paleontology) can be used to make very detailed predictions about what another, unrelated discipline (comparative genomics) should reveal. These results are also entirely consistent with the observation, made in the 1920s, that toothless whales form tooth buds during embryogenesis that are later reabsorbed prior to the point when the deposition of enamel would begin. As with the hind limb story in whale evolution, lines of evidence from genetics, paleontology and embryology converge to support the hypothesis that modern toothless whales descend, through modification, from toothed ancestors.

In the next post in this series, we’ll examine a few more lines of evidence for whale evolution, and extend our discussion to converging lines of evidence for the evolution of our own species.

For further reading:

Meredith, R.W., Gatesy, J., Cjeng, J., and Springer, M.S. (2011). Pseudogenization of the tooth gene enamelysin (MMP20) in the common ancestor of extant baleen whales. Proceedings of the Royal Society B: 278 (1708); 993 – 1002. Available online: http://rspb.royalsocietypublishing.org/content/early/2010/09/16/rspb.2010.1280.full.pdf

Ridewood, W.G. (1923). Observations on the skull in foetal specimens of whales of the genera Megaptera and Balaenoptera. Philosophical Transactions of the Royal Society of London B: 211; 209 - 272. Available online: http://rstb.royalsocietypublishing.org/content/211/382-390/209.full.pdf

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In our previous post, we examined processed pseudogenes – transcribed gene copies that randomly insert into genomes. Unitary pseudogenes, however, are different: unlike processed pseudogenes, they are unique sequences in genomes, and not copies. They have the features one expects of “real” genes: regulatory sequences, introns, and protein coding sections – but with mutations that prevent them from being transcribed or translated. Like buildings in various states of repair, there is a similar range for unitary pseudogenes. If they have only been recently inactivated, they will be largely intact – like a recently abandoned building with a few broken windows. Others are further along in their degradation, like a stone building without a roof and grass growing up through the floor. Some are so far gone that one needs to peel back the turf to search for what remains of the foundation. Despite their various states of disrepair, they remain recognizable – in some cases, they can persist for millions of years before they slowly mutate beyond recognition.

The reason for these defective genes is straightforward: the organism that had the original mutation that removed the function of the gene was not significantly impacted by the loss. One example I have previously discussed is the human GLO pseudogene. The functional GLO gene is part of the biochemical pathway for making vitamin C, something that humans and other primates are not able to do: if we don’t get enough in our diet, we get scurvy. In an environment with adequate dietary vitamin C, however, the loss of the GLO gene is no big deal – and mutations that remove its function would not have been a disadvantage. The mutations that remove GLO function in humans are the same mutations we see in other species – they are an example of mutations in a nested hierarchy, the type of pattern that relatedness produces. This indicates that the mutations happened once, in a common ancestral species, and have been inherited by several species that descend from that ancestor, ours included.

So, what’s a defective gene like you doing in a species like this?

While it makes sense that mammals ought to be able to make vitamin C (even if humans and other primates cannot), in some cases pseudogenes seem much more “out of place.” One example from the human genome that we have discussed in the past, is the vitellogenin gene, a gene required for egg yolk formation in egg-laying organisms. This gene is present in the human genome as a pseudogene, even though humans are placental mammals – human embryos are nourished through a placenta, not egg yolk. This pseudogene was located in the human genome by predicting that its genomic location relative to its neighboring genes would be retained for a long time, even after its inactivation. Accordingly, researchers found a functional vitellogenin gene in the chicken genome, and noted the genes on either side of it (let’s just call them “Gene A and Gene B” for convenience). Gene A and Gene B are also side by side in the human genome, so the researchers looked between them for the signs of vitellogenin gene remains – and found them in that precise spot, still visible despite approximately 300 million years since we last shared a common ancestor with chickens:

Other examples like this abound: whales, for example, have unitary pseudogene remnants of genes devoted to an air-based sense of smell, even in cases where the whale species in question does not have an olfactory organ. A second example from whales are pseudogene remnants of visual pigments adapted for wavelengths of light found in terrestrial settings, not aquatic environments. These examples make perfect sense in light of the terrestrial ancestry of whales, but are challenging to account for from an antievolutionary perspective.

Pseudogenes: evolution’s silver bullet?

Unitary pseudogenes with shared mutations in nested hierarchies among related species are far from the only evidence for evolution, and are not even necessarily the line of evidence most convincing to specialists. Specialists can see the broad pattern of multiple lines of converging evidence that support common ancestry to an extent non-specialists cannot easily appreciate. Unitary pseudogenes, however, are valuable tools for demonstrating a sampling of those lines of evidence, and providing a window into the world of comparative genomics that, to paraphrase Dobzhansky’s famous quote, would make absolutely no sense except in the light of evolution.

Yes, the implications of unitary pseudogenes such as these are easy for even non-specialists to grasp: whales have the defective remnants of genes adapted to terrestrial vision and air-based smelling because they descend from terrestrial ancestors. Placental mammals, including humans, have a defective remnant of a gene used to make egg yolk because they descend from egg-laying ancestors. Unitary pseudogenes share identical mutations across related species because they were inactivated in a common ancestor, and were inherited by every species that descended from that ancestral species.

No special training in genetics is required to appreciate the strength of the evidence that these examples provide. Nor does it require special insight to see that attempts made by antievolutionary groups to refute this evidence face an uphill battle. Its daunting nature notwithstanding, some have undertaken just that task, since the evidence is too compelling to ignore, and too risky to leave unanswered.

Bringing it together: antievolutionary approaches to pseudogenes, unitary and otherwise, miss the mark

Now that we have covered significant ground with respect to what various classes of pseudogenes are and how they arise, we are now able to properly evaluate antievolutionary arguments put forward in an attempt to discredit these lines of evidence for evolution. Attempts to discredit unitary pseudogene evidence generally have one or both of the following two approaches, which we will evaluate in turn:

Approach 1: Discuss rare examples of processed pseudogenes that have acquired function, and imply that all pseudogenes, including unitary pseudogenes, will similarly be shown to have function.

This approach is a fairly common one in the antievolutionary literature, and examples abound. We have examined previously how processed pseudogenes may, in rare cases, acquire a function and come under selection. Note well: the vast, vast majority of processed pseudogenes are not functional and are slowly mutating beyond recognition as DNA not under selection. While rare examples that have acquired function are very interesting from a scientific perspective, they do not “confer functionality” on the remainder of processed pseudogenes, let alone on unitary pseudogenes.

The other issue with this argument is that in many cases we know what the function of the unitary pseudogene once was. We know what the function of vitellogenin is, for example – and we can find this gene in modern-day egg-laying animals. When we see the remnants of this sequence in the human genome it is a stretch to argue that it has another, as of yet unknown function. When we see the human pseudogene sitting between two other genes in the human genome the same order as we observe in the chicken genome, it stretches credibility well past the breaking point.

Approach 2: Claim that unitary pseudogenes with mutations shared across species are the result of non-random mutations that occurred independently in the two species, and are not inherited from a common ancestor.

This argument, though having an appearance of validity, is similarly doomed to frustration. While mutations are not entirely random (certain regions of the genome mutate more readily than others) there is no known mechanism that could create the precise, repeated pattern of shared mutations we observe between related species. The most significant attempt to mount this type of argument against unitary pseudogenes in general was directed at the GLO pseudogene, and I have already discussed the specific details of why that attempt was inadequate. No refinement of that argument, to my knowledge, has been put forward since.

In summary, pseudogenes in general, and unitary pseudogenes in particular, remain a significant thorn in the side of antievolutionary groups. In the next post in this series, we’ll cast our net wider and explore an example of how multiple, convergent lines of evidence support evolution, often in unexpected ways.

For further reading:

http://biologos.org/blog/signature-in-the-pseudogenes-part-1
http://biologos.org/blog/signature-in-the-pseudogenes-part-2
http://biologos.org/blog/a-tale-of-three-creationists-part-3

In our previous BioLogos podcast, we looked at the question of transitional fossils, and how the transitional species story strongly supports evolutionary theory. In this podcast, we look at genetic evidence for evolution. The discovery of DNA has revolutionized our understanding of common descent, particularly in the past few decades. Mutated genes spread through populations over generations, leading to the change we know as evolution. Amazingly, deeper study of DNA lines up with Darwin's initial observations of the larger natural world. While it would take weeks to highlight all the genetic evidence for evolution, today we focus on a few specific examples: the similarity of genomes for related species, psuedogenes, and genetic markers left by retroviruses.

For more, be sure to read Dennis Venema's series "Signature in the Psuedogenes" and "Understanding Evolution".

Today's video is courtesy of filmmaker Ryan Pettey, director/editor of Satellite Pictures and features physicist Ard Louis.

In today's video, Oxford physicist Ard Louis discusses the famous debate between renowned evolutionary biologists Stephen Jay Gould and Simon Conway Morris. Gould believed (and wrote in his book Wonderful Life) that if the "tape" of evolution were rerun, the chance that anything like human intelligence would emerge is essentially zero. In other words, humanity is here through random accident. Gould pointed to the work of Morris and fellow scientists in their research of the Burgess Shale as evidence for this view.

However, Morris himself disagrees, pointing to what is called evolutionary convergence. As Morris notes, there are numerous examples of identical features evolving multiple times throughout the history of life independently. Morris believes that if the tape of life were replayed, we would see something like humans emerge. A Christian might say, it looks like we were planned.

Some Christians might find Simon Conway Morris' viewpoint, with its implicit teleology, more attractive. Others, perhaps motivated by a high view of providence, may find Gould's emphasis on contingency equally congenial to their faith. What do you think?