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.

What does it mean for humanity to be created “from the dust of the ground?”

In many ancient Mesopotamian creation stories, human beings were depicted as deriving from some physical part of the gods. Often this was the result of conflict: humans arose from the blood, flesh or tears of gods slain by other gods. Humans created in this fashion were supposed to serve the gods by performing menial work that the gods had tired of doing themselves. The lot of humanity, then, was one of violence and servitude.

In the Israelite creation stories reflected in Genesis 1 and 2, however, humans are made from the ordinary material of creation: “dust.” Humans are made of earth-stuff, not god-stuff.

At first glance, it may seem that this lowers the status of the human creature. We might ask the question raised by Eliphaz in the book of Job:

Can a mortal be more righteous than God?
Can even a strong man be more pure than his Maker?
If God places no trust in his servants,
if he charges his angels with error,
how much more those who live in houses of clay,
whose foundations are in the dust, who are crushed more readily than a moth! (Job 4:17-19)

Indeed, our humble origins ought to remind us of the fragility of our lives. As the Psalmist says,

You turn people back to dust, saying, “Return to dust, you mortals.”
A thousand years in your sight
are like a day that has just gone by,
or like a watch in the night.
Yet you sweep people away in the sleep of death—
they are like the new grass of the morning:
In the morning it springs up new,
but by evening it is dry and withered.

The elements of which our bodies are made are ordinary and abundant. Science tells us that approximately ninety-three per cent of the mass in a living human body is comprised of elements first formed through nuclear fusion in the hearts of stars. Through almost unimaginably vast and ancient cycles of stellar formation and supernova explosions, this “stardust” of elements has been spread throughout the universe. It is as though God scattered the stars across space and time to seed the universe for life, including your life and mine. And we are thereby inseparably connected to each other, to the air we breathe, to the ground we tread, to all the creatures that fill the skies and crawl upon the earth and teem in the seas, to the depths of all the heavens. We are not transcendent of creation. We are creatures.

Yet we are creatures into which God breathed the “breath of life.” We are stardust and more than stardust. We are not reducible to our constituent chemicals. A “man” or a “woman” is not just a gooey sack of water, carbon and trace elements. Hydrogen, oxygen and carbon are not aware of their own existence. These elements cannot reason or pray or love or write poems. Conjunctions of these elements cannot carry any persistent identity across time. They do not exercise will or intentionality or agency. They are not “selves.”

Most of the cells in a human body are in constant flux: aging, dividing, dying, being replaced. The surface layer of human skin is renewed completely about every two weeks. An adult’s skeleton is entirely remade over approximately ten year periods. It may be that only the neurons of the cerebral cortex and a few other types of cells persist throughout the lifetime of a human body. And eventually, it all does return to “dust.”

Yet we think of ourselves as persisting over time, as comprising an “identity,” a “self.” Perhaps the cerebral cortex provides the stable biological platform for identity and selfhood, but something new emerges from the chemical-electrical soup, new patterns of organization, a different level of causation. We can even make choices that reshape ourselves, both physically and psychologically. The very wiring of our brains changes when we make conscious choices. Mind is both shaped by matter and supervenes on matter.

Materialists who wish to collapse all of human identity into brain chemistry overstep the bounds of “science.” A fundamental principle of scientific practice is testability: is it possible to demonstrate empirically whether a proposition is false ? As Saint Augustine observed many centuries ago, the fact that I acknowledge I could be “wrong” about something means that I am a “self” who is capable of making real choices about things that are in fact true or false. “Si fallor, sum” Augustine said – if I can doubt, if I can be wrong, then I must exist. One who is a true materialist “all the way down” cannot test his or her materialism. There is no possibility of “being” right or wrong, indeed no possibility of “being” – there is nothing but chemistry.

Spiritualists who wish to degrade matter in favor of the soul or spirit likewise are not expressing a Christian anthropology. Indeed, one of the first heresies that encountered the early Christian church was Gnosticism. A core belief of Gnosticism was that matter, including the human body, was essentially evil. Salvation for the Gnostics involved the soul’s escape from the prison of embodiment and materiality. The Gnostics treated the body either with disdain – engaging in extreme ascetic practices – or with antinomian abandon – engaging in extreme sexual license. Either way, their practices were rooted in the belief that matter and the body were unimportant. It’s easy to see how this view continually creeps into both our popular culture and our Church cultures.

Christian theology asserts that humans are spiritual creatures, a unity of body and spirit or “soul,” integrated, not reducible downwards to mere matter or upwards to mere spirit. Perhaps there is no better way to bring these themes together than with a Psalm — here is Eugene Peterson’s paraphrase of Psalm 139 in The Message:

God, investigate my life; get all the facts firsthand.
I’m an open book to you;
even from a distance, you know what I’m thinking.
You know when I leave and when I get back;
I’m never out of your sight.
You know everything I’m going to say
before I start the first sentence.
I look behind me and you’re there,
then up ahead and you’re there, too—
your reassuring presence, coming and going.
This is too much, too wonderful—
I can’t take it all in!

Is there any place I can go to avoid your Spirit?
to be out of your sight?
If I climb to the sky, you’re there!
If I go underground, you’re there!
If I flew on morning’s wings
to the far western horizon,
You’d find me in a minute—
you’re already there waiting!
Then I said to myself, “Oh, he even sees me in the dark!
At night I’m immersed in the light!”
It’s a fact: darkness isn’t dark to you;
night and day, darkness and light, they’re all the same to you.

Oh yes, you shaped me first inside, then out;
you formed me in my mother’s womb.
I thank you, High God—you’re breathtaking!
Body and soul, I am marvelously made!
I worship in adoration—what a creation!
You know me inside and out,
you know every bone in my body;
You know exactly how I was made, bit by bit,
how I was sculpted from nothing into something.
Like an open book, you watched me grow from conception to birth;
all the stages of my life were spread out before you,
The days of my life all prepared
before I’d even lived one day.

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.

Transitional Fossils

Some time ago, the Discovery Institute’s Casey Luskin commented on the human origins exhibit at the Smithsonian Institution, suggesting that palaeoanthropologists use evolutionary theory to describe the progression of the human lineage even when they don’t have transitional fossils with which to work. He writes:

What's ironic, however, is that if you ask the question How Do We Know Humans Evolved? the answer you’re given is, “Fossils like the ones shown in our Human Fossils Gallery provide evidence that modern humans evolved from earlier humans.” So whether you find fossils or you don’t, that’s evidence for evolution.

Indeed, it has become an article of faith for those espousing both the young earth creation (hereafter YEC) model and many who hold to the intelligent design model that transitional fossils do not exist and therefore evolution has not taken place. Support for this position usually entails attacking the weak areas of the fossil record, where burial processes have left us little with which to work, or the creation of straw men arguments in which transitional fossils are defined in such a way that none could ever be found. Often this centers on the concept of “missing link,” a term that is habitually used in the popular press and young earth creation and intelligent design literature when referring to fossil remains but which has little to no meaning for biologists or palaeontologists. As Ahlberg and Clack (Ahlberg and Clack 2006) write:

But the concept has become freighted with unfounded notions of evolutionary ‘progress’ and with a mistaken emphasis on the single intermediate fossil as the key to understanding evolutionary transitions. Much of the importance of transitional fossils actually lies in how they resemble and differ from their nearest neighbours in the phylogenetic tree, and in the picture of change that emerges from this pattern.

Contrary to common misconceptions, the fossil record does not record one single lineage for any family of organisms but rather a series of branches, with many related species coexisting synchronously. Darwin hypothesized that the evolutionary record reflected this bushiness and drew such a diagram in his journal. At the time, though, he had little in the way of fossil evidence to back up this position. Much has changed since his day.

An analogy for understanding this “bushiness” was best described by Prothero and Buell (Prothero and Buell 2007). They suggest that the reader consider his or her own genealogy. You and your siblings are the direct descendents of your parents and, while you are similar to them, each of you has different characteristics not shared with them as well as characteristics that you do share. Your parents have siblings as well (your aunts and uncles), and your grandparents are their last common ancestors. These siblings have their own children (your cousins), who have different and similar traits relative to their parents. They are broadly recognizable as being related to you (“oh, I see you have Aunt Edna’s nose”) but three or four generations out, they will become less and less so. These are the “nearest neighbours” that Ahlberg and Clack describe. In this analogy, each of these cousins represents a transitional form from what was (your grandparents) to what will be down the road.

For example, no one would confuse a frog with a salamander but if you trace the fossil record of each back in time, eventually you encounter a fossil, Gerobatrachus hottoni which was recently discovered (Anderson et al. 2008) that is best described as a “frogamander,” having the basal characteristics of both frogs and salamanders. Had we seen such an animal at the time, it is likely we would not have found it remarkable because it would have resembled the species around it. One lineage eventually diverged into frogs, salamanders and other amphibians. Most (just like Darwin proposed in his tree diagram with the little hatch marks at the tip of many branches) went extinct.

Taxonomy and the Beginnings of Human Origins

All life is classified based on a system devised by Carolus Linneaus in 1735 in his remarkable work Systema Naturae. This system gives all recognized species an individual place based on a system of hierarchy. The study of classification is known as taxonomy. A taxonomic ranking for humans would be this:

When a fossil is excavated, the first thing that the palaeontologist does is make a taxonomic assessment of where it fits in a sequence of known fossils. Traits that are shared with other like species or genera are referred to as primitive traits. Examples of this in humans are five fingers and the presence of three arm bones. We share this with all mammals. Traits that are new or are not shared with other like species are referred to as derived traits. Examples of this in humans are the skeletal changes in the pelvis and the foot to allow for walking upright. We do not share these with any other primates.

Transitional fossils in the human fossil record are distinguished at both the genus and species level. This group includes the extinct genera Ardipithecus and Australopithecus and the current genus Homo. All species except Homo sapiens are extinct. Much of the recent study of early humans focuses on the transition from Ardipithecus (‘Ardi’) to Australopithecus (‘Lucy’ and similar fossils) and from Australopithecus to Homo, the genus that led eventually to us. While each of the australopithecine species identified in the fossil record has derived characteristics that separate them from their ancestors and from each other, only one led to the genus Homo.

In future posts, I will describe the evidence for human evolution and why this evidence is compelling. It suggests that we have had a long, varied history filled with great leaps of change, crushing defeat, and eventual expansion into all areas of the globe.

Notes

Ahlberg, P. & J. Clack (2006) A firm step from water to land. Nature, 440.

Anderson, J. S., R. R. Reisz, D. Scott, N. B. Frobisch & S. S. Sumida (2008) A stem batrachian from the Early Permian of Texas and the origin of frogs and salamanders. Nature, 453, 515-518.

Prothero, D. & C. Buell. 2007. Evolution: What the fossils say and why it matters. Columbia Univ Pr.

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.

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.

(Click Image for Full Resolution)

For more, be sure to read our FAQs How are the ages of the Earth and universe calculated? and What scientific evidence do we have about the first humans?, as well as our recent infographic How Do We Know the Earth is Old?.

Author's Note from Joy Walters

As I mentioned in my first post, I grew up skeptical of the whole idea of evolution. One contributor to my disbelief was the lengthy timescale for the “tree of life” that was presented with the theory. I would hear, for example, that dinosaurs lived hundreds of millions of years ago, but there was no explanation of why this was true; it was just given as a fact. No one explained the methods of dating, and so I thought biologists simply estimated the ages of species to fit their preconceived notions of how long it would take for one species to emerge from another. It also seemed like the ages were periodically revised and extended farther back in time, and I figured scientists needed to manipulate numbers to make evolution plausible. This, in my mind, made the theory both unbelievable and dismissible.

Once I learned about the techniques used to date fossils, I realized that my first impressions were wrong; the ancient ages of species are scientific determinations rather than scholarly conjectures. However, I have found in recent conversations that Christians remain skeptical of old ages and the evolutionary time scale. For this reason, I wanted the videocast to address the process of fossil dating (what the methods are and why they are accurate) while focusing on cases where hominid fossils were discovered and dated using these very methods. My hope is that Believers would be informed about the evidence for human evolution and its scientific grounding.

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.

Many posts on this Forum have suggested that the cosmological narrative in Genesis 1 is best read as being primarily about God’s identity and agency, rather than about the physical make-up or material history of the natural world. Similarly, we demonstrate our highest regard for Genesis 2’s account of the creation of Eve—the second fully human being—by looking to its meaning in terms of spiritual and interpersonal relationships, rather than genetic ones. While the specific “how” of our being made into the image of God will probably always remain a mystery, the Bible and creeds are clear on the “why” of our creation: we were made to worship the Lord, and be in relation with Him and each other. That intimate, conscious and deeply symbolic knowledge of our maker and fellow human beings is a profound difference that sets us apart from the other creatures.

I have frequently argued that poets are often the most clear on some of the important issues of our faith, including this one. Today we feature a work by Robert Siegel, who identifies the imagination as the faculty by which we recognize and name those spiritual relationships. As he says, “It's the imagination, hence language and art, that establishes the connections”; it is the imagination that allows us to conceive of and name the links between ourselves and creation, ourselves and each other, ourselves and the Creator God.

Though we often focus on Adam’s naming of the animals, and then even of Eve, Siegel helps us remember that it was in hearing his own name that Adam’s whole humanity came into being: he experienced the richness of being called by God to bear His likeness, but also of being called to by one that was profoundly “like him.” Put another way, we are speakers, but also equally hearers. May we, too, be awakened to ourselves and our image-bearing identity by a still, soft voice saying our name. May we, too, in gratitude and delight, call upon the name of the one, Jesus, who is both our God and our fellow man.

“Adam’s Dream”

by Robert Siegel

The Imagination may be compared to Adam's dream:
he awoke and found it truth. --Keats

He saw the garden spreading past the trees
he'd been warned to avoid (yet keep a special eye on).
He'd learned by scents, transported by the breeze,
myriads of roses and how, by hand, the scion

of one to graft on another--and what was edible:
whole families of legumes, grasses, roots,
melons, peaches, apples, pears. Incredible,
the variety of tastes just from the fruits!

But it wasn't enough. Even the breathing animals
with friendly grunt or sigh, silken warm side,
and large affectionate eye were not able
to speak. When he named them, none replied:

His words fell dead on the air--though he said
them everywhere, walking or running to each place:
to the mountain, which echoed back the sounds he made,
or the still pool, returning his own gaze.

But no one answered him until one night in a dream
he woke and heard a soft voice speak his name.

“Adam’s Dream” first appeared in issue 3 of Stonework, the literary journal of Houghton College. © 2001 Robert Siegel

Robert Siegel is the author of nine books of poetry and fiction, most recently A Pentecost of Finches: New and Selected Poems. He has received prizes and awards from Poetry, Prairie Schooner, The Transatlantic Review, the Ingram Merrill Foundation, and the National Endowment for the Arts, and his poems have appeared in numerous journals and anthologies. His fiction includes Alpha Centauri and the Whalesong trilogy, which received the Golden Archer and Matson awards. With degrees from Wheaton, Johns Hopkins, and Harvard, Siegel has taught at Dartmouth, Princeton, and Goethe University in Frankfurt, and for twenty-three years at the University of Wisconsin-Milwaukee, where he directed the graduate creative writing program and is currently professor emeritus of English. He is married to Ann Hill Siegel, a photographer, and lives on the coast of Maine.