One of the more outspoken proponents of this view is Sam Harris, a leading figure among the New Atheists, and a fierce antitheist. Harris has written a book and given talks on the idea that morality—broadly, the act of discerning good from bad—can be derived from science.

On the face of it, this seems strange, since the scientific consensus, especially in evolutionary biology, has always been that nature is morally neutral. We know, as scientists, that sharks are not “bad” any more than dolphins are “good.” The true evolutionary view (I always thought) was that fitness is related to success, not goodness.

The problem is that as human beings, we know that goodness exists, so it must be accounted for, and if one is a staunch believer in scientism, it must be accounted for scientifically. In some situations, this accounting seems to be possible. There is a large literature on kin selection as the basis for some kinds of altruism, and Dawkins has made the case that what he calls “misfiring of genes” for kin altruism are responsible for human goodness.

Harris claims that moral values can be based on scientific principles, and that no kind of cultural context, especially faith-based context, is necessary for humans to have a code of morals. He bases this argument on the idea that moral values are based on facts, and that these facts can be tested for their truthfulness. To some extent, this is an old idea. Murder, adultery, theft and lying—some of the best-recognized universal moral prohibitions, all tend to destabilize the coherence of social groups and would therefore be selected against in all societies.

But Harris goes much further, using arguments and examples that are anything but scientific. Since Harris is a leader of the antitheistic movement, and is interested in finding examples of religious practices that he believes can be scientifically proven to be immoral. He cites the abusive treatment of women in Islamic societies as a main example, and he mentions corporal punishment of children as a slap at Christianity.

So how does Harris prove scientifically that forcing women to cover their bodies, and hitting school children with rulers are morally wrong? He doesn’t. Here is what he actually says:

But we can ask the obvious question: Is it a good idea, generally speaking, to subject children to pain and violence and public humiliation as a way of encouraging healthy emotional development and good behavior? Is there any doubt that this question has an answer, and that it matters?

Harris clearly believes the answer to that question is no, and I agree with him. But where is the science here? Has he data to show that children who were subjected to corporal punishment had worse emotional development and behavior than children who did not undergo such punishment? No. He has no such data, and in fact while he considers the wrongness of corporal punishment to be an obvious fact, there are millions of people who consider it to be just the reverse. There is no science here; there is simply a basic underlying moral idea, which Harris shares with others.

Harris touts the evils of Islamic fundamentalism as morally indefensible from a scientific point of view. But what kind of fact is it to say that making women cover their bodies is wrong, other than the “fact” that Harris thinks it is? Is there a science for determining the optimal way to treat women? If there is, it isn’t mentioned by Harris. 

While it may seem obvious that the oppression of women is morally wrong, proving scientifically that its disadvantageous to the thriving of our species is more tricky. In fact, the moral values of Harris, which are typical Western Judeo-Christian values, are largely counter-evolutionary. What we see when we look at history or sociology, is a background of true selection-positive behavior—indiscriminate killing of enemies, sexual aggression, concentration of power in a dominant faction—on which has been superimposed a moral code, followed and enforced despite its anti-evolutionary tendency. The real question to ask is: How is it that humans obey any of these moral codes that do not help them survive as individuals or as members of a culture?

In truth, there is no science at all behind Harris’s grand claim of factual moral values, (beyond such obvious things as it isn’t a good idea to add cholera germs to the water supply). He even admits this by stating:

Now the irony, from my perspective, is that the only people who seem to generally agree with me and who think that there are right and wrong answers to moral questions are religious demagogues of one form or another.

Of course that is correct, because both Harris, and the people whom he calls “religious demagogues,” have formulated moral codes that they hold to in the absence of any “scientific” data. 

The argument that morality is outside the scope of science is not a hard one to make, but it isn’t only morality that must be excluded from the domain of science. The more important argument is that very few of the ideas of evolutionism are based on anything remotely scientific. This is because the evolutionism paradigm includes many distortions of Darwin’s great theory, and too many of these distortions have become accepted by an antitheistic academic culture without proper rigorous analysis. 

Like Steven Jay Gould, I see no evidence that the biological mechanisms of evolution by natural selection can be extrapolated beyond the bounds of biology. Gould devotes several chapters in The Richness of Life to attacking the “adaptationist paradigm,” which is a central part of evolutionism. In responding to Daniel Dennet’s assertion that adaptation and selection explain just about everything, Gould says:

The fallacy of Dennet’s argument undermines his other imperialist hope that the universal acid of natural selection might reduce human cultural change to the Darwinian algorithm as well … The chief strategy proposed by evolutionary psychologists for identifying adaptation is untestable and therefore unscientific.

Cunningham has also explored this issue in Darwin’s Pious Idea. Social Darwinism, eugenics, evolutionary psychology, sociobiology, mimetics and other nonbiological applications of Darwin’s theory are not rationally consistent with the fundamental properties of evolution by natural selection. 

Evolutionism has been used to “explain” all sorts of dynamics in culture, using evolutionary concepts. But, while the evolution of devices that play music (as an example) might bear a resemblance to the evolution of carnivores, it is a superficial resemblance. Devices do not replicate themselves, so they cannot be the target of selection. 

Scientism is a failed philosophical approach to the pursuit of universal truth. Its failure should be evident especially to scientists who, more than most, understand the limits of their fields of study, as well as the enormous effort it takes to wrest nuggets of pure truth from nature. We must, as previous generations of enlightened thinkers have done, admit that issues of morality, beauty, thought, love, art, and culture are not approachable by scientific methodology or tools, or we risk losing a huge part of our human endowment of special (if not divine) genius.

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.

Morality, or more strictly our belief in morality, is merely an adaptation put in place to further our reproductive end.

Important scientific theories invite philosophical and theological reflection. Dawkins, Ruse, and Wilson, have described their conclusions. But scientific theories are often compatible with multiple philosophical and religious interpretations. For example, Newton's laws of motion and gravity allow several competing theistic and atheistic interpretations.

To avoid Ruse and Wilson's philosophical conclusion, we need not dispute their scientific hypothesis about how morality evolved. We need only dispute their philosophical extrapolation as to why morality exists. Even if we restrict ourselves to an atheistic worldview, this extrapolation is questionable. Donald MacKay (1965) would call this an example of "the fallacy of nothing but-tery". This is the assertion that a description of something at one level renders other levels of description meaningless. From our everyday experience, we know that a successful description on one level does not invalidate other levels of description. For example. one might assert that a Shakespeare sonnet is "nothing but" ink blots on a page (MacKay 1965). True, one way to describe a sonnet is to precisely specify the page coordinates of every ink blot. This description is valid and complete on its own level; however, one could also analyze the sonnet linguistically, emotionally, socially, historically, and on other levels. If one is programming an inkjet printer, the most important description is in terms of ink blot coordinates. For almost every other purpose in life, however, that is an unimportant level of description. In the same way, a complete evolutionary description of the existence of morality does not necessarily invalidate the truth, utility, or significance of other levels of description of morality.

If we do not restrict ourselves to atheism and instead allow for the existence of a creator, the extrapolation from how morality evolved to why morality exists fails further. Consider an analogy. Suppose an inventor builds a robot which could do a variety of useful things-- mow the lawn, clean the house, grade homework, write book chapters, and so on. One thing this robot can do, given a complete set of spare parts, is build a replica of itself. Whenever the inventor needs another robot, she gives one robot a set of spare parts and has it build a replica of itself. Amongst all the software subroutines within this robot, there is a set of subroutines that govern the robot's self-replication, including the replication of those self-replication subroutines. Would it be correct to say that the purpose of the robot's existence is merely to reproduce those particular self-replication subroutines? Do all of the other software and hardware of the robot--which allow it to mow the lawn, and so on-- merely further the reproductive ends of those self-replication subroutines? At one level, the robot's hardware and software do serve to reproduce those self-replication software routines. At another level of analysis, however, those self-replication software routines serve the robot to produce more copies of itself. At still another level, those self-replication software routines serve the robot's creator. The creator of the robot should get the last world as to which of those levels of description is most important.

In humans, does morality exist to further the reproduction of certain genes, or do those genes exist in order to allow for the production of new human beings who can behave morally? If human beings have a creator, the creator gets the final word on the question of purpose. The mechanism which the creator used to make those genes-- whether de novo or via evolution-- is secondary. The creator's purpose in creating those genes decides the issue.

References

• Dawkins, Richard. 1976. Pp. 1-11 in The Selfish Gene. Oxford: Oxford University Press.
• MacKay, Donald. 1965. Christianity in a Mechanistic Universe. Chicago: InterVarsity.
• Ruse, Michael, and Edward O. Wilson. 1993. The approach of sociobiology: The evolution of ethics. In Religion and the Natural Sciences, ed. James E. Huchingson. Fort Worth: Harcourt Brace Javonovich.

Today, as I write, I am no longer in the desert of southern California, nor in the beech-maple forest of New Hampshire, but on a glacial drumlin in Waubesa Wetlands—a large marsh four miles south of Madison, Wisconsin. Here Ruth and I have our home, and here I study creatures whose watery habitats my neighbors and I have worked to save from eventual destruction. While my desert study site now is covered by a city where people live alone in the land—absent the desert creatures—my wetland study site remains occupied by all kinds of native plants and animals. Embracing it is the Town of Dunn, whose land stewardship plan helps people understand, serve, and maintain this and the other ecosystems. Our town stewardship plan encourages restoration of the landscape, protects agricultural lands, and strives to transmit an intergenerational heritage of secure and wholesome homes, livelihoods, and habitats for the animals, plants, and people that live here. We live largely in harmony and accord.

House-building on slabs poured onto desert sands first alerted me to the question of praxis, the third point on the napkin. But it was later, in my work as organizer of the Waubesa Wetlands Scientific and Agricultural Preserve, and as supervisor and later as chair of the Town of Dunn, that I came to realize that science and ethics do no earthly good unless put into practice. In serving my town, I came to apply what I had learned in the desert: praxis uninformed by science and ethics usually creates more problems than are solved.

“How do you put it all together?” those students in New Hampshire wanted to know. For me, it was building a framework for stewardship that simultaneously considered the questions “How does the world work?” “What is right?” and “What then must we do?” This science-ethics-praxis triad is a framework for living, for learning, for teaching, and most importantly for acting. It is a framework for stewardship.

In order to live and act rightly in the world, we need to know how the world works. We need to know how the systems that sustain us work, and how we interact with them. Without such knowledge we could drown in a flash flood, have our homes undercut by desert winds, cross the street in the path of an oncoming car, or get sick from consuming foods with toxic ingredients. As human beings develop more and more of the world, and as the reach of human actions extends regionally and globally, our knowledge must increase accordingly. This knowledge is not limited to what we acquire from a formal education; it also includes the knowledge we gain from family and friends, and from experience and experiment. In order to live and act rightly in the world, we need to know how the world works.

In order to live and act rightly in the world, we need to know what we ought to do. A century ago, this question was addressed in many colleges across America in a course for graduating seniors on moral philosophy. The purpose of this course was to convict students that they should apply their knowledge for the pursuit of good instead of pursuing self at others’ expense. At my university, this aspect of college education is expressed in a quotation from Abraham Lincoln carved in stone on a bench behind Lincoln’s statue at the top of Bascom Hill: “Let us have faith that right makes might, and in that faith, dare to do our duty.” The question “What is right?” is represented by the ethics corner of our triad. Moving directly from the Science corner to the praxis corner, or from the ethics corner to the praxis corner, proves problematic, even disastrous. Consider the result of going from knowledge of nuclear fission (science) directly to producing and dropping an atomic bomb (praxis), or moving from the belief that death is bad (ethics) to removing dead wood from forests (praxis); both are examples of these disastrous shortcuts.

But knowing the science and observing the ethics of this stewardship framework does absolutely no good if it is not put into practice—placed into service. By themselves, the very best science and the most substantial ethics are no substitutes for action. We need to act appropriately and deliberately in the light of scientific and ethical knowledge. Praxis by itself, without being grounded in science and ethics, results in mere activism—activism that is unlikely to do good and that may produce harm. All three corners of the triad are essential—but not by themselves. Taken together and working interactively, they provide a framework for stewardship.

But will these three operate in dynamic interaction? Will they interact in ways that preserve and achieve the integrity of human life and the environment? The answer depends on what we know and understand about ourselves and the world (science), what we believe we should do (ethics), and what we in fact do, and how we respond to our successes and failures (praxis). It depends on our will, our motivation, our determination, and our dedication to strive for a harmonious world of creatures before their Creator. What might make us strive for such a world?

Part 3 explores the challenge of translating ideals into concrete actions.

A careful study of this chapter is important because it gives us a beautiful picture of the proper relationships we should have with God, the natural world, and each other. Numerous posts could be written on each of these relationships, but in this post I’d like to focus on how Genesis 2 describes our relationship to the rest of creation. These relationships are given deeper significance when we recognize that the garden is being described as a temple-like “sacred space,” not just an ordinary garden. There are numerous clues in the passage that this is the case. John Walton writes that the Garden/temple parallels “are givens that are simply assumed by the author and audience” ¹ of Genesis, but we completely miss them if we take fail to read the text the way the ancient author and audience would have.

Temples and Gardens

In the Ancient Near East (ANE), all sacred space was conceived of as something like a temple; it was a place where humans would serve God and experience their closest access to Him. Thus in ANE cultures, a temple complex was seen as being the apex and a microcosm of creation and the earthly abode of the god(s). Descriptions of temples often pictured a river flowing from under the temple and flowing out through an adjacent garden, symbolizing the fertile extravagance of the divine provision. A temple garden would be no mere backyard vegetable patch, but rather an elaborate, beautifully landscaped botanical park.

The same temple/river picture can be seen in the description of the eschatological temple in Ezekiel (ch. 47) and Revelation (chs. 21-22, where the final temple is God Himself). Sound familiar? In Genesis 2 we also have a river flowing “from Eden [‘Abundance’] to water the garden” (v. 10).² Not only is the Garden filled with “every beautiful tree with edible fruit” (v. 9), but the area itself is rich with gold, resins, and gemstones (sometimes translated “bdellium and onyx”), the same materials later used to decorate Israel’s tabernacle, temple, and priestly garments. Furthermore, many scholars are convinced that the design of temple’s Menorah (candlestick) deliberately echoes the Garden’s Tree of Life, and some also think that the Ark of the Covenant in the temple parallels the Tree of the Knowledge of Good and Evil.³

Made for Sacred Service

As inhabitants of this temple-garden, it comes as no surprise that Adam and Eve enjoyed a special closeness to God’s presence (Gen. 3:8 pictures God taking an evening walk through the Garden). But as inhabitants of the Garden, they had special responsibilities as well; they were told “to farm it and take care of it” (v. 15). The two Hebrew words used here have a broader range of meaning than their English translations suggest. As John Walton writes, the broader meaning of the word here translated “to farm” (particularly when used in a sacred context) “is often connected to religious service deemed as worship (e.g., Ex. 3:12) or of priestly functionaries serving in the temple precinct (e.g., Num. 3:7-10).” ⁴

The usage in Genesis 2 seems to have two layers of meaning: “farm/cultivate the Garden” (since it is an agricultural space) and “serve/worship God” (since the Garden is also a sacred space). The dual meanings are as intertwined in Hebrew grammar as they are intended to be in practice. The second Hebrew word (translated “take care of”) has a deeper religious meaning as well. The word can refer to protecting farmland from external threats, but in a danger-free sacred space like the Garden, the word more generally refers to “performing duties on the [temple] grounds,” that is, to “sacred service.”⁵

Walton therefore translates these two Hebrew words as “serve and preserve.” These same words appear again together several times in Numbers to describe the priest’s duties in the temple. Because of all this, Gordon Wenham describes Adam as “perhaps…an archetypal Levite” with a “quasi-priestly” role in the garden.⁸ Eve was created as Adam’s companion and “helper” in his work, a word which nowhere in the OT refers to a subordinate assistant, but rather to one who is at least equal to the one being helped.⁹

Genesis 2 should banish from our minds any idea that creation care is somehow “secular” work for a Christian, or that it is not even our responsibility. This was the first task given to humanity, to serve and worship God by cultivating and protecting the natural world. The centrality of our responsibility in this regard is even clearer when we back up to the beginning of the chapter. We know there was a river “flow[ing] from Eden to water the garden” (v. 10), symbolizing that “all fertility emanates from the presence of God.” ¹⁰ Nonetheless there could be no cultivated plants in the garden because “there was still no human being to farm the fertile land” (v. 5). With no gardener and no rain, the ground was watered indiscriminately; a human was needed to irrigate the waters and support a garden.¹¹ Therefore, God “formed the human from the topsoil” (Hebrew wordplay equivalent to “human from the humus”) before planting the garden. God certainly could have watered it another way without needing us, but He chose not to, and the resulting collaborative picture here is a beautiful one. All provision flows from God, but He has chosen to give us an essential part in further channeling his provisions in the natural world. Far from countering God’s creative work by destroying nature, we are intended to work with Him to preserve and further it.

Of course, though created primarily to glorify God, the world was also made to provide us abundantly with the food and resources that we need to live (Gen. 2:16). Yet we don’t need to look far to see that we have often failed in our responsibility to properly care for creation. We live in a fallen world, and sin has fractured the intended harmony of our relationships with God, creation, and each other (as described in Genesis 3:14-24).

I recently heard a striking crystallization of this fallen perspective in Spencer Tracy’s narration in the opening scene of the sprawling 1962 western film “How the West Was Won.” As the camera flies over majestic Western fields and mountains, the narrator tells us that “This land has a name today, and is marked on maps. But the names and the maps all had to be won, won from nature and from primitive man.” This is the fallen perspective – advancing our human purpose on earth is done through defeating nature and other people (derogatively labeled “primitive,” as well) apart from God. This perspective perfectly illustrates the conflict-based relationships that sin brings about, already described for us back in the first chapters of the Bible.

Are we doomed, then, to live helplessly in this way? If this is just the way the world is and the way we are, shouldn’t we just accept that? Apart from Christ the answer would be “yes,” but the New Testament makes it clear that though we are still fallen, the saving work of Christ has brought about a profound change in us. As N.T. Wright makes clear in his book Surprised by Hope, Jesus taught (and the Resurrection vindicated) that the Kingdom of God “was and is breaking in to the present world, to earth.” ¹² Christ’s Resurrection was the first act of the future new creation. If we are truly “born again” into this new reality, this new way of living, we must strive (in the Spirit’s power) to live lives of wholeness and right relationships, putting our sinful nature to death (Colossians 3). In doing so, we would be wise to include Genesis 2 as we seek to follow God’s will and God’s Kingdom, “on earth as it is in heaven” (Matt. 6:10).

In part 2 of this series, David describes how Genesis 1, Genesis 2, and modern scientific accounts offer complementary and mutually enriching perspectives in our understanding of God's creation.

Notes

1. John H. Walton, Ancient Near Eastern Thought and the Old Testament: Introducing the Conceptual World of the Hebrew Bible (Grand Rapids, MI: Baker Academic, 2006), 125.
2. Biblical quotations are from the Common English Bible unless otherwise noted.
3. Both symbolized divine wisdom that humans had to receive from God obediently, with the proper “fear of God” that the Old Testament wisdom literature stresses as a prerequisite. Disobediently eating the Tree’s fruit would lead to death and disobeying God would lead to expulsion from the Garden. Similarly, disobediently touching the Ark brought death (Num. 4:15, 2 Sam. 6:1-7) and disobeying God’s instruction led to Israel’s exile from their Eden, the land of Canaan.
4. John H. Walton, Genesis (Grand Rapids, MI: Zondervan, 2001), 172.
5. Ibid., 173.
6. Ibid., 192.
7. See Numbers 3:7-8, 8:26, 18:5-6.
8. Gordon J. Wenham, “Sanctuary Symbolism in the Garden of Eden Story,” in “I Studied Inscriptions from Before the Flood”: Ancient Near Eastern, Literary and Linguistic Approaches to Genesis 1-11, ed. Richard S. Hess and David Toshio Tsumura (Winona Lake, IN: Eisenbrauns, 1994), 401.
9. Walton, Genesis, 176.
10. Ibid., 170.
11. This follows Walton’s illuminating exegesis of this passage in Genesis, 164-65.
12. N.T. Wright, Surprised by Hope: Rethinking Heaven, the Resurrection, and the Mission of the Church (New York: HarperOne, 2008), 201.

Introduction

One of the reasons that some of us are hesitant to accept evolutionary creation is that it seems to make God responsible for the suffering and death of innumerable creatures over millions of years—before humans ever existed or sinned against their creator. Since we believe in and worship a God who is loving, benevolent, and all-powerful, it sounds quite implausible that our God would have created a world like that; therefore, any scientific evidence for evolution must be incorrect.

Other people look at the scientific evidence for evolution and find a compelling case that it has taken place during our earth's history. On this basis they may conclude that if evolution is true, then the belief in an all-powerful, perfectly good God must be false!

The trouble with both of these views is that they tend to invoke a completely abstract, philosophical god, not the living God of the Bible—the God who became a human being, experienced unimaginable suffering, and died in a grotesque and humiliating public display. The death of Jesus completely defied the expectations (and common sense) of his followers, as well as the expectations of any “rational” understanding of the way the Creator of the universe should act in the world. On the cross, in the person of Jesus, God took upon himself far more suffering than any creature has ever experienced.

If God himself is willing to die, particularly in such a gruesome way, then perhaps we should at least consider the possibility of God allowing the death of other creatures, too. But would this really be compatible with what we know of God through Scripture? In this essay, we will explore this quandary through a “theology of the cross”, a concept articulated by pastor George Murphy in his book Cosmos in the Light of the Cross.¹

Theology of the cross

Before we jump into the theological problems associated with evolution, let’s take a look at how we understand Christian theology itself. For the reformer Martin Luther, any theology (or science) that tries to reach knowledge of God apart from the cross is bad theology.² Instead, Luther pointed to a theologia crucis, in which the true God is seen first and foremost “through suffering and the cross”. To make his point even clearer, Luther insisted that “the CROSS alone is our theology”.³ It is the lens through which we view everything.

Of course Martin Luther, having lived in the 16th century, was not aware of the vast history of life on our planet (or any other aspect of modern science, for that matter), but George Murphy draws from Luther’s teachings the foundation that all human knowledge begins with the Word made flesh and crucified.⁴ With the cross of Christ as the ultimate framework through which we view reality, we are bound to view the processes of nature quite differently. As Murphy explains it,

A theology of the cross is an explication of belief in a God who becomes a participant in the history of the universe and thereby shares in the suffering, loss, and death that are part of worldly experience.⁵

God does not sit idly by and watch unaffected as his creatures suffer, but neither does he swoop in and make everything completely effortless and easy. Instead he chose another way, the crucifixion of Jesus—certainly not the approach that we would have preferred! The apostle Peter went so far as to try to talk Jesus out of it, but he was met with a stern rebuke (Matthew 16:21-23).

Why is evolution so disconcerting to Christians?

The problem of suffering throughout all of human history is troubling enough for us to reconcile with a loving, personal God. But in addition to that, the discovery of vast numbers of fossils reveals that death has taken place on a far greater scale than we had ever imagined. Both the wide variety of extinct creatures and their sheer numbers is quite staggering, and it raises questions about our Creator:

The picture of a God who is immune from suffering and death but who forces organisms through millions of generations and extinction is disturbing to those who believe in a God of love.⁷

The mass extinction of life on earth was already well established by the early 19th century—decades before Darwin’s research—and extinction can be empirically verified independent of any theory of evolution.⁸ The fact that the earth’s crust is a veritable graveyard of long-lost creatures is deeply troubling, and as late as the 1790’s, distinguished intellectuals such as Thomas Jefferson denied the very possibility of extinction.⁹

But in addition to the reality of species extinction, the theory of evolution by natural selection proposes that new species also arise in an environment containing widespread pain and death. Both the creatures that are now living and those that are gone are tainted by an “acrid smell of death”.¹⁰ It makes us wonder, if our Creator is not the God of the dead, but of the living (Mk. 12:27), where is God’s presence in the evolutionary picture?

In all honesty, creation through evolution is not what we would expect from God, but Scripture is full of examples in which God acts in unexpected ways. After all, God’s choosing to undergo an agonizing death on a cross is not what we would expect from the all-powerful Creator of the universe, either. In both cases, new life comes about through pain, suffering, and death. As George Murphy puts it,

A priori ideas about God have to be overcome, and God's character has to be learned from God's self-revelation.¹¹

God’s fullest self-expression is in Jesus Christ himself, one who is intimately familiar with and personally endured creaturely pain and death. The theology of the cross reveals that God's self-revelation takes place in situations of suffering, loss, and apparent hopelessness, much like situations that occur through natural selection.¹²

The crucifixion is disconcerting too

Not only is creation through evolution an unexpected and unsettling process, but so is the crucifixion of Jesus! Killing someone by hanging them on a cross is an unbearably painful, prolonged, humiliating form of death. It was such a horrific type of public execution that it wasn't until after the Roman Empire stopped the practice of crucifixion—and people no longer witnessed it personally—did the cross become a visual object of devotion.¹³ Our culture is sufficiently removed from crucifixion that we are desensitized to its original significance, but to connect it to our current context, imagine the reaction you would get by wearing jewelry designed to look like an electric chair.¹⁴

Once we are more attuned to the brutality of crucifixion, it seems all the more striking that the cross is the sign of God’s work, what George Murphy calls “the trademark of God”.¹⁵ The suffering and death of Jesus is featured prominently in the Gospels, but the crucifixion-resurrection pattern is strongly resonant within the Old Testament, too. Israel suffered and toiled as slaves in Egypt for centuries before they were rescued in the Exodus, bringing life to a people who were spiritually dead. Centuries later, the nation of Israel would experience death again when the Babylonians destroyed the Davidic monarchy, burned their Temple, killed their people, and sent many into exile.¹⁶ Neither Israel (God’s chosen people) nor Jesus (God’s own son) were spared from death and suffering; rather, suffering seems to have been the way in which God re-forms and renews humanity to fully bear His own image.

Redemption extends to all of creation

Fortunately, God’s story does not end with death. God gives new life after his creatures have been subjected to terrible circumstances. Redemption was promised to Israel itself—Ezekiel’s vision of the valley of dry bones describes how God would renew His chosen people (Ezek 37:1-14). Later, the astonishing resurrection of Jesus made salvation possible not only for Jews, but for all people in Christ (Gal 3:26-29). Ultimately, the New Testament makes it clear that God’s renewal will encompass the entire Creation:

For God was pleased to have all his fullness dwell in him, and through him to reconcile to himself all things, whether things on earth or things in heaven, by making peace through his blood, shed on the cross. (Colossians 1:19-20)

With all wisdom and understanding, he made known to us the mystery of his will according to his good pleasure, which he purposed in Christ, to be put into effect when the times reach their fulfillment—to bring unity to all things in heaven and on earth under Christ. (Ephesians 1:8-10)

Christians are accustomed to thinking of the death of Christ in regard to humans, but our culture rarely acknowledges God plan for the redemption of His entire creation. This is partly attributable to the fact that discussions of creation and origins are often separated from the topic of salvation.¹⁷ In doing so we tend to marginalize Jesus as we argue about Genesis. Rather than fall into this trap, if we view nature through a theology of the cross, we will see Christ as both the alpha and the omega point in discussions of life’s history and life’s future. With this perspective, we are more apt to sense our solidarity with the rest of creation as we wait in eager anticipation of a glorious future:

The creation waits in eager expectation for the children of God to be revealed. For the creation was subjected to frustration, not by its own choice, but by the will of the one who subjected it, in hope that the creation itself will be liberated from its bondage to decay and brought into the freedom and glory of the children of God. (Romans 8:19-21)

Conclusion

As part of the Church’s conversation about the problem of natural evil, this essay is meant to be a brief introduction to a “theology of the cross”. One can explore this concept in greater detail in Murphy’s book The Cosmos in the Light of the Cross. While there is a lot more to be said, let me conclude with the following observation: though evolution may not be compatible with some interpretations of Christianity, evolutionary creation is certainly compatible with the crucified Christ and the theology of the cross. In the person of Jesus, God suffers with the world and ultimately redeems it. As George Murphy puts in, “The world's pains are God's stigmata.”¹⁸

Explore this Topic Further

• Miller, Keith. “And God saw that it was good”: Death and Pain in the Created Order. BioLogos series
• Murphy, George L. The Cosmos in the Light of the Cross. Harrisburg, PA: Trinity Press, 2003.
• Murphy, George L. “Cross, Evolution, and Theodicy: Telling It Like It Is”. In The Evolution of Evil. Edited by G. Bennett, M.J. Hewlett, T. Peters, and R.J. Russell. Göttingen: Vandenhoeck & Ruprecht, 2008.
• Southgate, Christopher. The Groaning of Creation: God, Evolution, and the Problem of Evil. Louisville, KY: Westminister John Knox Press, 2008.

Notes

1. Murphy, George L. The Cosmos in the Light of the Cross. Harrisburg, PA: Trinity Press, 2003.
2. Murphy, p34
3. “CRUX Sola Est Nostra Theologia,” in D. Martin Luthers Werke, Kritische Gesammtausgabe (Weimar: Hermann Boehlau, 1892), 5:172. The captitalization is in the original. Cited in Murphy, p26.
4. Murphy, p108
5. Murphy, p4
6. Murphy, p43
7. Murphy, p3
8. Some Christians ascribe animal death to some combination of Adam’s fall and Noah’s flood, but this does not resolve the problem that the animals are still suffering and dying through no fault of their own. See Keith Miller’s BioLogos series Death and Pain in the Created Order for the limitations inherent in a fall-based theodicy.
9. Rudwick, Martin. The meaning of fossils: Episodes in the history of paleontology. Chicago, University of Chicago Press, 1985.
10. See Jeff Schloss’ BioLogos essay Evolution, Creation, and the Sting of Death
11. Murphy, p63
12. Murphy, p122
13. Murphy, p27
14. This example is drawn from an evangelical outreach event held by a Christian student group in Innsbruck, Austria. On campus one day, they started conversations with their classmates by asking the question, “Would you wear an electric chair on your neck?”
15. Murphy, George L. The Trademark of God: A Christian Course in Creation, Evolution, and Salvation. Wilton, Conn.: Morehouse-Barlow, 1986.
16. Murphy, Cosmos in the Light of the Cross, p 31-32.
17. Murphy, p35
18. Murphy, p87

In Part 2 of this series, we concluded by noting that, as Christian geologists willing to consider the possibility, we find no compelling evidence that the earth’s geological features can be explained by a global Flood. Here we consider three lines of evidence: global salt deposits, the order of deposition of sediment layers in the Grand Canyon, and the sequence of fossils in geological strata.

Salt Deposits

There are many places around the earth with layers of salt, some thousands of feet in thickness. Just off the southern coast of the United States in the Gulf of Mexico, thick salt deposits sit beneath thousands of feet of sediment (Fig. 1). These deposits lie within the layers that are said to have been deposited by the Flood.

We understand how salt beds form. At locations such as the Bonneville Salt Flats of Utah, or at the Dead Sea at the border of Israel and Jordan, salt is actively forming. Salt beds form when water is evaporated. During evaporation, the concentration of dissolved ions increases until the water cannot hold the salt in solution anymore and mineral salt begins to form. If a presently unknown or poorly understood process could produce salt without evaporation, as argued by young-earth advocates¹, it would quickly dissolve as soon as it came into contact with flood water, just as the salt from your saltshaker rapidly dissolves when added to water or moist food.

One might argue that the waters from the Flood could have evaporated to leave behind the salt deposits we see today, but there is a serious problem. The thousands of feet of sediment on top of the salt is also said to be from the Flood, meaning the flood waters cannot have evaporated to produce the salt and still be present and violent enough to transport thousands of feet of sediment to the same location. In other words, a single flood cannot be called upon to explain both the salt and the overlying sediment. For those who wish to argue that natural processes could have been vastly different during the Flood, there are at least two replies. First, under such a scenario, there is no point in Flood Geology studies any more than in normal studies, for nothing could be gained by the study of unknowable processes. A more important question, however, would be to ask why God would alter natural processes just to make Flood sediments look like they are not flood sediments. What would the purpose be? (We will revisit this thought later.)

Grand Canyon: Order of Deposition

The Grand Canyon is made up of a sequence of layers that defies any reasonable attempt to explain by a single flood. The alternating layers of limestone, sandstone and shale each form in unique environments. If these deposits were formed at different times under various sea-level stages, it is quite simple to explain the different grain sizes and rock types as a function of depth and distance from the shore line. If explained with a single catastrophic flood that abided by God’s natural laws of physics and chemistry, logic must be stretched beyond the breaking point.

As a very simple observation, consider instructions given in virtually every gardening book. A good soil will have a mix of sand, silt and clay. To determine the quality of your soil, you take a handful or two, put it in a clear container, add water and shake it up. When you stop shaking, the coarse grained material will settle out first resulting in a sequence of layers: sand on the bottom, then silt, then clay. You can readily see how much of each you have by the thickness of each layer.

This is informative of what we see in flood deposits. As moving flood waters slow down, finer and finer grained sediment settles out resulting in a “fining upward” sequence. If most of the Grand Canyon layers were laid down by the Flood, then we should see the same thing – a “fining upward” sequence. Instead, we see a series of alternating layers of fine and coarse grained material, with smaller-scale alternating layers within the larger ones (Fig. 2). Increasing the violence of a flood does nothing to negate the standard order of deposition. Repeated surging of flood waters across the surface likewise offers little explanatory power; in this case we might expect successive layers, each with their own “fining upward” sequence, but such is not what is observed. Further, the Grand Canyon includes multiple layers of limestone, which are never found in flood deposits of any magnitude. Even in floods as massive as one thought to have catastrophically deluged the once dry Mediterranean Sea basin with thousands of feet of water – limestone beds are conspicuously absent.

Fossil Sequence

If a massive flood were responsible for the fossil record, what would we expect to see? If the Flood was violent enough to rip chunks of rock up from the earth and move entire continents (standard Young Earth claims)², then it should be obvious that life forms from every imaginable niche would be tumbled and mixed together (Fig. 3a). We should find numerous examples of mammoths mixed with triceratops, and pterodactyls mixed with sparrows. Ferns and meadow flowers should be found in the same deposits, along with trilobites and whales. Further, we should find all major life forms still living today, for Genesis 7:8-9 is clear in stating that all terrestrial animals were preserved on the ark.

What we actually observe is far different (Fig. 3b). There is an orderly sequence where trilobites only occur in very old rocks, dinosaurs in later beds, and mammoths in still later layers. Organisms like flowers and ferns are present together in more recent deposits, but only ferns with no flowers are found in older deposits. Some readers will recognize this as an example from the “geologic column” and be tempted to discount it as a fabrication. For those thinking this way, consider what Henry Morris had to say in both editions of Scientific Creationism:

“Creationists do not question the general validity of the geologic column, however, at least as an indicator of the usual order of deposition of the fossils…”⁵

If we revisit the Grand Canyon for a moment, is it not striking that there is not a single dinosaur, mammoth or bird in the entire exposed sequence? Not one. To find these, you have to go to younger sediments found in deposits outside the canyon that have not been fully eroded away yet. How could such a lack of mixing be possible if the Flood was violent enough to move continents?

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.

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?

In our previous essay, we learned that a tree summarizing species relationships can be built using DNA information, and how we can use DNA as a “molecular clock” to date ancient events. Both of these methods have made specific predictions about the origin of whales. If evolution is true: whales are related to the even-toed hoofed mammals and should share common ancestors with them; transitional fossil forms dating from about 45 to 50 million years ago should be found which can be shown to be related to both the even-toed hoofed mammals and modern whales; whales are most closely related to modern hippos, and should share a common ancestor with them.

What other types of information might we be able to use to construct a phylogenetic tree (i.e. a family tree) of species relationships? It turns out that characteristics of body structure also can be used – for example, the presence or absence of certain bones, or the specific shapes of those bones. An advantage of using bony features is that they can be recovered from fossils, whereas DNA (with only certain limited exceptions) must come from living organisms.

We can also derive functional information from an examination of bony features. The various protrusions, bumps and knobs found on bones usually have important implications. For example, smooth rounded areas at the ends of bones allow them to fit together and move easily. The shapes of such surfaces determine which bone motions are “allowed” or “disallowed”. Consider, for example, the motion of the forearm against the upper arm at the elbow. This is a “hinge” joint, whose normal motion is defined by the shapes of the upper arm bone and one of the forearm bones, where they meet each other. You might normally exercise the action of this hinge joint when you pick up a cup of coffee, bring it to your mouth, then set it back down again. Let’s try to imagine another motion. For this exercise we first need to get our arm into the proper starting position. Place your arm at your side, bent at the elbow at a ninety degree angle, with your palm up. Now, while keeping your palm up, let’s attempt to move your arm only at the elbow (no shoulder motion – that’s cheating!). Now swing your forearm out to the side and attempt to end up with your fingers pointed directly away from your side. Most of you will not be able to do this. If you can, it’s because your shoulder is rotating in spite of yourself. This motion at the elbow is normally not allowed. Hence a careful analysis of bone shapes can allow us to infer how the bones were used. This in turn can assist us in the task of phylogenetic (evolutionary) classification of organisms. That is, we will have more confidence in the grouping together of animals in our tree diagram if corresponding bones are used functionally in the same way.

Therefore we would expect that we could use various bony features to help us examine the predictions generated by our previous look at different types of DNA data. Are there any bony features that are particularly relevant to the even-toed hoofed mammals? Well, it turns out that there are. These are mainly running animals, and there are several features of their ankle bones, which taken together define the “allowed” motions which make them efficient runners. If one takes the various ankle bones of a large group of mammals, examines them carefully to note their shapes, scores that information into a table, then uses a computer program to build a phylogenetic tree, it turns out that all the even-toed hoofed mammals are placed together. So far, so good. But what about whales? Well, now we have an obvious problem. Modern whales are very specialized, - they have flippers which correspond to the forelimbs, and they have almost no hind limbs! I say “almost” because they do have small pelvic bones, which are not attached to the rest of their skeletons. But they certainly have no ankles. This is where the fossils should come in – if evolution is true, we should expect to be able to identify transitional fossils which are ancestral to whales which contain the characteristic ankle bony features of the even-toed hoofed mammals.

Now let’s look at bony features from the whale perspective. We have already mentioned the almost complete loss of hind limbs, and the presence of forelimbs modified into flippers. In addition, as air breathers, whales have a blowhole at the top of their skull. And as powerful swimmers, which use a large tail fluke in vertical motions, whales have enormous sets of muscles which attach to enlarged projections from their vertebral column. So if evolution is true, we should begin to see fossil forms which manifest changes in bony features which correspond to the gradual accumulation of these whale-like characteristics. However, we still need more, because these various bony features all would be expected to occur in largely or exclusively aquatic forms. We might expect this to correspond to the later stages of a transition from terrestrial even-toed hoofed mammals. But what about the earlier stages? It would be very helpful if we had some “defining” characteristic of whales, similar to the ankle structure of even-toed hoofed mammals.

It turns out that the structure of the bones of the skull and ear apparatus of whales are highly modified to allow efficient hearing underwater. The mechanical aspects of efficiently receiving sound through water are somewhat different than receiving sound travelling through air. If evolution is true, we should expect to be able to find key transitional fossil forms with a progressive series of modifications of the skull and ear bones, features which would not be found in any other mammals.

Now that we know what we should expect to see, if evolution is true, let’s look at what has actually been found in the fossil record. Over the last fifteen years or so, a series of fossils, many of them discovered in the Indian subcontinent, have fulfilled nearly all of our predictions.^1,2 Let’s look at the figure below (Figure 1), reproduced from a recent popular book on evolution.³ This shows a series of fossils, arranged in approximate chronological order, with a modern whale at the top. How old are these fossil forms? The entire fossil progression illustrated occurs from a little over 50 million years ago to about 40 million years ago. So a remarkable alteration in general body form occurred in a little over 10 million years. This time frame agrees well with the previous prediction from the DNA “clock” that we discussed in our previous essay. Second, the general change in body shape corresponds to what we predicted in our discussion of whale bony features above. That is, there is a gradual elongation and streamlining, there is a modification of the forelimb into flippers and progressive reduction of the hindlimb, the nostrils for breathing move toward the top of the skull to form a blowhole (not obvious from the diagram), and the vertebrae develop enlarged projections to support the attachment of swimming muscles.

Figure 1: Skeletons and Body Forms of Modern Whales and Fossil Ancestors
The reconstructed skeletons (black) from modern whales (top) and various ancestral skeletal forms (series below) are in chronological order (from Pakicetus up). Indohyus is an extinct whale “cousin”. Relative body size, to scale, is indicated by the gray shapes at the right of each animal.

There is probably little question that the last fossil species in the figure (Durodon) is well on the way to becoming a modern whale. However, it might be argued by a skeptic that the earlier species (like Rhodocetus, Ambulocetus, or Pakicetus), despite the “cetus” (whale) part of their names, are not so obviously “whale-like” that they deserve to be considered as fossil whale ancestors. However, remember the characteristic whale skull modifications for hearing? It has been shown very clearly that throughout this series of fossil species, the various bony changes necessary to support efficient hearing in water were being acquired in a stepwise fashion. Organisms earlier in the sequence had skeletal characteristics consistent with them being able to hear well in both air (using the “classic” mammalian hearing apparatus), and newly acquired changes to also allow better hearing in water. Later organisms in the sequence become increasingly specialized for hearing in water only.⁴

What of the earliest fossil shown in this diagram –Pakicetus? Careful examination shows that it has the features we would predict for an early whale ancestor. It has the ankle bone characteristics of the even-toed hoofed mammals (in fact these features are also found in several of the later fossil forms as well, ensuring their continuity). This confirms one of the predictions made by the DNA evidence we discussed earlier. Furthermore, it has some of the modifications of the skull bones necessary for more efficient underwater hearing, which were previously documented only for modern whales and their later (more obvious) ancestors.⁴ These features are also shared with the “whale cousin” Indohyus.⁵ Preservation of more of the skeleton of this latter species has allowed detailed analysis indicating characteristics likely shared with whale ancestors. Indohyus was probably a wading animal, which spent much of its time in the water. It appears to have fed mostly on land, so it is suggested that resort to the water was made to escape predators.⁵

Finally, we need to look back at the last prediction from our previous DNA evidence, namely that modern whales are most closely related to hippos. If evolution is true, we should expect to find fossil forms linking these two modern groups. This has proven to be a tougher nut to crack, mainly because the ancestral whales first appear about 50 million years ago in what is now south Asia, and the hippo family first appears about 15 million years ago, in Africa. The most recent tree diagram, produced by using a combination of skeletal features and DNA data, still supports this family connection, as shown by the following figure (Figure 2).⁶

Figure 2: Phylogenetic Tree Showing the Relationship of Modern Whales to Living and Extinct Even-Toed Hoofed Mammals
This tree is based on both bony features and DNA data. The organisms presented in blue are semi-aquatic or aquatic forms. Organisms shown in green are terrestrial even-toed hoofed mammals (Artiodactyls). In black is shown a member of the odd-toed hoofed mammals. In red is an extinct fossil ancestor group. (This figure is adapted from Fig 1a in Reference 6).

The blue lines in the diagram show species in which the skeleton is specially thickened, and the bone structure more dense. This is an adaptation which allows wading animals (like modern hippos and the fossil Indohyus) to be good “bottom-walkers” (it prevents them from floating due to lighter body tissues), and allows fully marine organisms (like modern whales) to have “neutral buoyancy” (so they don’t always tend to pop up to the water surface, like a cork). There has also been progress in clarifying the relationships between fossil ancestors of hippos and those of modern whales. A recent study of hippo evolution, based only on skeletal characteristics, has conclusively shown that the hippo family are descended from an extinct group of fossil Artiodactyls, known to go back more than 40 million years, and whose fossils are from southern Asia. Furthermore, this study produced a phylogenetic tree predicting that this extinct hippo ancestor group also shared a common ancestor with the fossil whales.⁷ Thus the investigation of hippo origins is independently leading us back toward the origin of whales. However, in this study the statistical support for predicted common ancestor of the ancient hippo group and the ancient whale group is not as strong as scientists would like to consider this “case closed”. What is necessary is more fossils, of the appropriate age in order to complete the story of hippo evolution. We still need that to fill in the details of the predicted relationship of hippos to modern whales.

Thus the “Whales’ Tale” is not yet complete. It is a story of scientific discovery in progress. As we finish, let’s briefly summarize what we have found out. Different types of DNA evidence agree that modern whales are most closely related to the even-toed hoofed mammals, despite the obvious great changes in limb anatomy of the modern whales. This prediction has been amply confirmed by the fossil record. The DNA sequence evidence predicted a time frame during which critical early events in evolution of whale ancestors should occur. This prediction has also been amply confirmed. Finally, DNA evidence predicts that modern whales are most closely related to hippos. There is some fossil evidence supporting a predicted common ancestor, but more data is needed. A final caution to possible sceptics – this state of “unfinished business” is precisely how the scientific process works. There is no “crisis”. There is no indication that evolution is not true. There is simply the ongoing work of mapping out of various lines of evidence. A scientific conclusion is considered well supported if “all roads lead to Rome”. In the case of whale evolution it might be prudent to say that the evidence has not quite converged in Rome yet, but that we are now in the suburbs. That is precisely what makes science interesting and fun. Stay tuned!

The next blog in this series can be found here.

References:

1: Thewissen J.G.M., Williams E.M., Roe L.J. and Hussain S.T. 2001. Skeletons of terrestrial cetaceans and the relationship of whales to artiodactyls. Nature. 413: 277-281.

2: Gingerich P.D., ul Haq M., Zalmout I.S., Khan I.H., Malkani M.S. 2001. Origin of Whales from Early Artiodactyls: Hands and Feet of Eocene Protocetidae from Pakistan. Science. 293:2239-2242.

3: Coyne, J.A. 2009. Why Evolution is True. Viking Penguin, New York. Pg 50.

4: Numella S., Thewissen J.G.M., Bajpai S.,Hussain T., Kumar K. 2007. Sound Transmission in Archaic and Modern Whales: Anatomical Adaptations for Underwater Hearing. The Anatomical Record. 290:716-733.

5: Thewissen J.G.M., Cooper L.N., Clementz M.T., Bajpai S., Tiwari B.N. 2007. Whales originated from aquatic artiodactyls in the Eocene epoch of India. Nature. 450:1190-1194.

6: Geisler J.H. and Theodor J.M. 2009. Hippopotamus and whale phylogeny. Nature. 458:E1-E4.

7: Boisserie J.-R., Lihoreau F., Brunet M. 2005. The position of Hippopotamidae within Cetartiodactyla. Proceedings of the National Academy of Sciences U.S.A. 102(5):1537-1541.

Today's video is courtesy of filmmaker Ryan Pettey, director/editor of Satellite Pictures.

In this video, physicist Ard Louis discusses the misconceptions about evolution and what it says about our purpose. A lot of the young earth arguments against evolution, says Louis, can be beneficial to those promoting atheism. According to Louis, both sides are attempting to extract theology from the natural world and wrongly accept the premise that where we come from determines who we are and how we should live. However, that’s not what the Bible tells us; rather, our value comes from God, and God determines who we are and how we should live.

Many understand evolution as a theory underlined by the idea that our existence is purposelessness. But our value and purpose do not come from whether or not we were created by an evolutionary mechanism. Evolution may tell us something about how we were created, but it is not the source of our worth. That worth comes from God.

For more from Ard Louis, be sure to read his white paper for BioLogos.

In the rest of the series, we will look closely at the evolutionary explanation for the blueprint. That explanation postulates that tetrapod limbs arose during a particular era in life's history, and that they arose as modifications of the fins of fish. And the evolutionary explanation isn't just an interesting idea. It's a comprehensive explanation – it helps us to understand bones, fossils, genes, chemical signaling systems. It provides a coherent framework for understanding why limbs are the way they are, and how they got that way.

Comparing the anatomy of tetrapod vertebrates and fish

The idea that tetrapods arose from fish is not new; E.D. Cope proposed in 1892 that tetrapods descended from lobe-finned fish. (Modern lobe-finned fishes include coelacanths and lungfish, and comprise one of two divisions of the bony fishes. The other division, the ray-finned fishes, includes most familiar kinds of fish.) In the early days, biologists inferred ancestral relationships between species largely through comparative anatomy and embryology: they would carefully classify organisms according to their structure (including their structure during development) and look for relationships that generated nested hierarchies. A simple nested hierarchy goes something like this: 1) animals with backbones; 2) animals with backbones and limbs; and 3) animals with backbones, limbs, and hair. Animals in group 3 also belong to groups 1 and 2, while animals in group 2 also belong to group 1, and so the groups together define a nested hierarchy. Such studies alone could have led some scientists to infer an ancestral relationship between fish and tetrapods, and perhaps those studies did convince them. But then there were fossils of various types of fish and other vertebrates, many long extinct. That fossil record was relatively sketchy in 1892, but it nevertheless led Cope and others to conclude that certain fish had given rise to tetrapods at a particular time in natural history.

The fossil record shows a fish-to-tetrapod transition

Here are some basic findings from the fossil record that suggest a fish-to-tetrapod transition and that have been known for decades:

• Fish, including fish with bones, lived on the earth before tetrapods appeared. Specifically, fossils of bony fish first appear in rocks from about 420 million years ago.

• Tetrapods appear in the fossil record at a particular point in history and then persist and diversify in subsequent eons. Their arrival was long thought to have occurred about 365 million years ago, although some recent findings have challenged that hypothesis.

• Tetrapods that still had some fishy features were prowling the planet 365 million years ago.

• Lobe-finned fish that were starting to look more like tetrapods were eating other fish about 385 million years ago.

Even many decades ago, there were hints that something interesting happened between 400 million years ago and 365 million years ago. Let's take a close look at the ancient animals that suggest the fish-to-tetrapod transition.

Ancient animals

The most primitive known tetrapods for which we have skeletal remains lived 365 million years ago. They were undeniably tetrapods, but there was definitely something fishy about them. (Heh heh.) One of the most famous of these creatures is Acanthostega, discovered in 1987 by British paleontologist Jennifer Clack and pictured below. Acanthostega is a card-carrying tetrapod, with fingers and toes. But it has a fish tail, with fin rays. Another well-known primitive tetrapod is Ichthyostega, which lived around the same time as Acanthostega. Like Acanthostega, it is a true tetrapod, but has several odd fish-like structural features. For example, its skull is more fish-like than that of Acanthostega. In summary, both Acanthostega and Ichthyostega already used the limb blueprint, even though both also had some fish-like anatomical characteristics. Their presence 365 million years ago shows that tetrapods must be at least that old, and their mixture of anatomical features suggests that the transition happened not long before that.

And what about the lobe-finned fish that looked a bit tetrapod-ish? That animal is Panderichthys, described as “vaguely crocodile-shaped” with skeletal features that were tetrapod-like. Specifically, this ancient fish had tetrapod-like “shoulders,” and recent analysis found some finger-like bones at the ends of the fins. The creature also had a breathing hole on the top of its head. These fish lived around 385 million years ago.

The hunt for the earliest tetrapods

Taken together, these observations suggested that the fish-to-tetrapod transition occurred between 385 and 365 million years ago. Eager to see what that transition looked like, scientists began to look for 375 million-year-old rocks in which they might find animals at the beginning of tetrapod-hood. They wanted to catch evolution in the act.

Let's stop and think about this, because it's cool and because it's important to note the extent to which evolutionary biology is hypothesis-driven. Critics of evolution sometimes portray the theory as an untestable historical conjecture, depicting it as fundamentally different from experimental science in the lab. But the hunt for the earliest tetrapods was an effort to test a hypothesis that had generated a prediction. Based on the hypothesis that lobe-finned fish were ancestors of tetrapods, scientists predicted that intermediate animals, “fishapods,” would be found in the gap between Panderichthys and Acanthostega. To evaluate the prediction, all they needed to do was find some suitable 375 million-year-old rocks.

Neil Shubin describes that search in the first chapter of Your Inner Fish. He and his colleagues found suitable rocks in the islands of the Arctic: the right age, nicely exposed (by erosion), and representative of the kind of environment that their quarry would frequent – freshwater streams. They made their biggest discovery on their last trip (“a do-or-die situation”) in 2004. That discovery was Tiktaalik roseae, the “fishapod.”

The “fishapod”

Tiktaalik roseae is one of the most extraordinary fossil intermediates ever described, and its public debut in 2006 was front-page news. An artist's conception of the animal is pictured below.

There are several aspects of the anatomy of Tiktaalik that earn it the title “fishapod.” Like a good fish, it had scales and webbed fins. Like a tetrapod (more specifically, like a crocodile), it had a flat head, with eyes on the top of the head, and it had a neck. But what about those fins? Or are they limbs? Remarkably, the answer seems to be, “both.”

The fins of Tiktaalik were part fish fin, part tetrapod limb. On the outside, they looked like fins, with webbing. On the inside, though, these fins were clearly tetrapod-like. Amazingly, the fins of Tiktaalik were built using a primitive version of the limb blueprint: one bone, two bones, blobs, digits. As Shubin writes in Your Inner Fish, “We had a fish with a wrist.” (The Tiktaalik roseae web site at the University of Chicago is a great source for images and more information.)

Let's address three questions about Tiktaalik that might have occurred to you. First, why might animals like Tiktaalik have developed tetrapod-like fins? Shubin and his colleagues suggest that these limb-like fins may have been useful for doing “push-ups” in the shallow water. (Like Panderichthys, Tiktaalik had a breathing hole on top of its head and was clearly adapted for living and moving in shallow water.) Second, is Tiktaalik an ancestor of all tetrapods? No, not necessarily. What Tiktaalik shows us is that animals were developing tetrapod features in the context of fish bodies, and Tiktaalik shows us the context (shallow water) in which this likely occurred. But that doesn't mean that our lineage arose from Tiktaalik itself. Finally, is Tiktaalik now the oldest tetrapod? No, apparently not. For one thing, Tiktaalik is truly transitional, and probably therefore not worthy of full tetrapod membership. But more notably, data published in 2010 show that tetrapods are a lot older than was thought at the time of Tiktaalik's discovery. The new findings show footprints that are unmistakably those of a tetrapod, in rocks about 395 million years old. Surprisingly, then, tetrapods were already on their way long before Neil Shubin's specimen lived. Tiktaalik is truly a fish/tetrapod intermediate, which was living at the same time as animals that were fully tetrapods. A simple story of succession, in which intermediates disappear and are replaced by less intermediate types, seems to be an oversimplification.

In conclusion, the fossil record provides evidence that the fins of fish and the limbs of tetrapods are related by ancestry: limbs seem to be modified versions of fins. What other evidence supports this proposal? In the next post, we will turn to developmental biology, and explore the meaning of the term 'homology.'

Further reading:

Neil Shubin (2009) Your Inner Fish: A Journey Into the 3.5-Billion-Year History of the Human Body. New York: Vintage Books.

Carl Zimmer (2006) A Fin is a Limb is a Wing: How Evolution Fashioned its Masterworks. Online at NationalGeographic.com.

Tiktaalik roseae website at the University of Chicago.

Jennifer Clack's website at the University of Cambridge.

Images are from Wikipedia.

The men, women and children we met were using teachings of faith as directives to care for the environment, and they were courageously confronting the central questions of what it means to be human in the midst of a culture of profligacy and consumption: What is our relationship and responsibility to all life on this planet, and to our Creator? How can we become better stewards of the environment and build a sustainable future?

RENEWAL presents eight grassroots stories about people who have been spiritually called to environmental action. Each story is set in a different faith tradition, addressing a different environmental concern. The film includes several Christian stories with one focusing on Evangelicals bearing witness to the sin of mountaintop removal coal mining that is decimating Appalachia and has been denounced in formal resolutions by the Lutheran, United Methodist, Presbyterian, and Episcopal churches. While the entire film runs 90-minutes, each story on the RENEWAL DVD is easily accessible as a short stand-alone film.

The emerging religious-environmental movement has been thrilling to document for its potential to bring about deep and lasting changes that can impact the earth. Addressing issues of consumption, pollution and stewardship, the religious movement promises to make a difference and motivate action in ways that the secular environmental movement has not yet been able to do.

One of RENEWAL’s stories, about the Reformed Church of Highland Park, NJ, portrays church members motivated by their faith to make changes at every level, to reduce their waste and become more low-impact stewards of the earth. This is typical of what is happening now in many houses of worship across America as people are becoming part of the religious-environmental movement.

It makes an enormous difference once you look at environmental protection in more than political, economic or scientific terms – once you understand it’s essentially a personal moral, ethical and spiritual issue. Today many people are discovering that caring for the environment is not only about endangered fish or imperiled birds or wilderness areas that most of us will never see. It’s about our deepest connection with the entire web of life, and with our Creator. And it’s about the choices that each of us makes, day to day.

In our early days of filming, the most striking thing we discovered was the lack of communication among groups who profoundly understood the deep bond between human beings and the earth – and who were already doing faith-inspired work to protect the environment. Most people assumed they were alone in taking action and that they wouldn’t be able to accomplish much – but they were acting anyway, out of a sense of spiritual calling to create a more mutually enhancing way of living with the planet. When we told them about others like them whom we'd met, they were usually surprised and delighted; the news provided a sense of strength and solidarity. We hoped the film would do that on a larger scale: offering a mirror to others whose faith inspired them to creation care across the country, showing them an image of their own good work and assuring them that they were not alone.

It’s been gratifying to watch the growth of this movement and to see the expanding role that Evangelicals are now playing in it. More and more are stepping forward to say that their faith in God has compelled them to find new ways of living with the planet, God’s gift to us. They’re doing it at home, in their churches and in the arena of public policy. Motivated by faith and by Scripture, Evangelicals are taking an active stand to strive for environmental awareness and build a more sustainable future.

Today, the religious-environmental movement – known as creation care to some – is emerging on the map of American consciousness, thanks in part to the continuing growth of Evangelical organizations and individuals who have discovered a calling in their biblical faith tradition to be stewards of the earth.

These include Allen Johnson and Christians for the Mountains (working to save Appalachia from the devastation of mountaintop removal coal mining); Peter Illyn and Restoring Eden (helping Christians, especially youth, rediscover the biblical call to environmental stewardship); the Evangelical Environmental Network (offering biblically inspired education and advocacy that relates to the moral aspects of public policies on energy and the environment); the Au Sable Institute of Environmental Studies (integrating environmental studies with biblical principles to bring the Christian community and the general public a better understanding of the stewardship of God’s creation); Matthew Sleeth, MD (author of Serve God, Save the Planet: A Christian Call to Action, a personal account of how Christian faith inspired significant changes in the way he and his family were living); Susan Emmerich, environmental activist / filmmaker (When Heaven Meets Earth, telling the story about the positive work-practices impact her faith-based stewardship approach has had in several Christian communities) and many others.

These exemplary Christian individuals and organizations have turned their faith into action, heeding the words that The earth is the Lord's, and everything in it (Ps. 24:1), that we have a responsibility to Speak up for those who cannot speak for themselves (Prov. 31:8) and that the sanctity of nature comes from God, for There is but one Lord, Jesus Christ, through whom all things came and through whom we live. (I Cor. 8:6b)

Today, as our nation faces the most daunting ecological challenges of human history, it is increasingly evident that religious communities have a critical leadership role to play by raising their voices to speak out for peace and better stewardship of the earth. Christians have a brilliant opportunity to lead the way at the personal, community and political level.

As filmmakers, we’re proud that RENEWAL has become a positive and powerful influence in the growth of creation care throughout the nation. As a recent article explained, RENEWAL aims to help people “recognize they’re part of a moral and spiritual movement to save the earth and discover a new relationship with the planet.”

The inspiring stories in RENEWAL (which you can learn more about here) are typical of many stories that are now multiplying in religious communities across the nation. These are not only stories about renewal of the earth; they are stories about renewal of the soul and the experience of reinforced faith for those who become engaged in this great work of our time.

Perhaps, then, it is fitting that Earth Day, a day celebrating environmental renewal, falls so close to Easter, the season of spiritual renewal, this year. It is a perfect time to spread the word and celebrate that creation care, the religious-environmental movement, is truly here!

Introduction: What’s all the fuss?

The most fundamental claim of biological evolution is that all living organisms represent the outer tips of a diversifying, upward-branching tree of life (click image to enlarge). The “tree of life” is an extremely powerful metaphor that captures the essence of evolution. Like the branches of a tree, as we trace individual lines of descent (lineages) back into the past (down the tree) they converge with other lineages toward their common ancestors. Similarly, these ancient lineages themselves converge with others back in time. Thus, all organisms, both living and extinct, are ultimately connected by an unbroken chain of descent with modification to a common ancestral trunk among single-celled organisms in the distant past.

This tree metaphor applies as much to the emergence of the first representatives of the major groups of living invertebrates (such as annelids, snails, or arthropods) as it does to the first appearance and diversification of dinosaurs, birds, or mammals. This early diversification of invertebrates apparently occurred around the time of the Precambrian/Cambrian boundary over a time interval of a few tens of millions of years. This period of rapid evolutionary diversification has been called the “Cambrian Explosion.”

The Cambrian explosion has been the focus of extensive scientific study, discussion, and debate for decades, and is increasingly receiving attention in the popular media. It has also received considerable recent attention by evolution critics as posing challenges to evolution. These critics argue that the expected transitions between major invertebrate groups (phyla) are absent, and that the suddenness of their appearance in the fossil record demonstrates that evolutionary explanations are not viable.

What are some of the arguments of the evolution critics? John Morris of the ICR writes:

“If evolution is correct, the first life was quite simple, evolving more complexity over time. Yet the Cambrian Explosion of Life has revealed life's complexity from the start, giving evolution a black eye. The vast array of complex life that appears in the lowest (or oldest) stratigraphic layer of rock, with no apparent ancestors, goes hard against evolutionary dogma. Evolution's desperate attempt to fill this gap with more simple ancestral fossils has added more injury. .... Think of the magnitude of this problem from an evolutionary perspective. Many and varied forms of complex multi-celled life suddenly sprang into existence without any trace of less complex predecessors. There are numerous single-celled forms at lower stratigraphic levels, but these offer scant help in solving the mystery. Not one basic type or phyla of marine invertebrate is supported by an ancestral line between single-celled life and the participants in the Cambrian Explosion, nor are the basic phyla related to one another. How did evolution ever get started?”¹

Intelligent design advocate Stephen Meyer and others have written:

“To say that the fauna of the Cambrian period appeared in a geologically sudden manner also implies the absence of clear transitional intermediates connecting the complex Cambrian animals with those simpler living forms found in lower strata. Indeed, in almost all cases, the body plans and structures present in Cambrian period animals have no clear morphological antecedents in earlier strata.²

And:

“A third feature of the Cambrian explosion (as well as the subsequent fossil record) bears mentioning. The major body plans that arise in the Cambrian period exhibit considerable morphological isolation from one another (or “disparity”) and then subsequent “stasis.” Though all Cambrian and subsequent animals fall clearly within one of a limited number of basic body plans, each of these body plans exhibits clear morphological differences (and thus disparity) from the others. The animal body plans (as represented in the fossil record) do not grade imperceptibly one into another, either at a specific time in geological history or over the course of geological history. Instead, the body plans of the animals characterizing the separate phyla maintain their distinctive morphological and organizational features and thus their isolation from one another, over time.”³

Are these critiques warranted? To what extent is the Cambrian explosion really problematic for the evolutionary picture of an unbroken tree of life extending back to the earliest life on Earth?

Geologic Time Scales: How big was the bang?

The relative rapidity of the diversification of invertebrates during the Cambrian “explosion” is set against the backdrop of the Earth’s geologic and biologic history. Geologic time is unfamiliar to most people, and its shear vastness is difficult to grasp.

Two lines of evidence impact our understanding of the duration of the animal diversification that led to the appearance of the major groups of living invertebrates. The first is the dating of critical strata within the geological timeline such as the Precambrian-Cambrian boundary and various important fossil-bearing horizons. The second is the time of appearance of the first widely recognized fossil representatives of the major living groups (phyla) of invertebrate animals. The latter is in considerable flux as new fossil discoveries are made.

Originally, the base of the Cambrian had been set at the earliest appearance of organisms with mineralized skeletons - particularly trilobites. However, a diverse collection of tiny mineralized plates, tubes and scales was discovered to lie below the earliest trilobites.⁴ This interval of “small shelly fossils” was designated the Tommotian. Because of the presence of even earlier tiny mineralized tubes and simple burrows, there was no internationally accepted definition for the boundary until 1994. At that time, the base of the Cambrian was placed at the first appearance of a particular collection of small fossil burrows characterized by Treptichnus pedum.

Until the early 1990's the age of the Precambrian-Cambrian boundary was not tightly constrained, and was estimated to be about 575 million years ago. However, in 1993 new radiometric dates from close to the accepted Precambrian-Cambrian boundary revealed that it was significantly younger -- about 544 million years.⁵ A more precise date of 542 ± 0.3 million years has recently been formally accepted by the International Commission on Stratigraphy. The basis for this date was the discovery that a sharp worldwide fall (or negative spike) in the abundance of the isotope carbon-13 was coincident with the Cambrian boundary as previously defined. In Oman, this isotopic marker also coincides with a volcanic ash layer that yielded the 542 million year date using uranium/lead radiometric methods.⁶ This horizon also marks the last occurrence of several fossils characteristic of the underling late Precambrian Ediacaran Period.⁷ Such extinction events are commonly used to subdivide the geologic time scale.

The earliest diverse fossil invertebrate communities of the Cambrian are represented by the Chengjiang, in China. These deposits are dated at 525-520 million years. The famous Burgess Shale is considerably younger, dating at about 505 million years, and the end of the Cambrian Period is set at 490 million years. The Cambrian Period thus lasted for 52 million years. To put this in perspective, the time elapsed since the extinction of the dinosaurs at the end of the Cretaceous has been 65 million years. The Cambrian was a very long period of time.

If the Cambrian explosion is understood to comprise the time from the base of the Cambrian to the Chengjiang fossil beds, then this period of diversification in animal body plans appears to have lasted about 20 million years. However, not all living animal phyla with a fossil record first appear within this time window. The colonial skeleton-bearing bryozoans, (click for image) for example, are not known from the fossil record until the end of the Cambrian around 491 million years ago.⁸ More significantly, several living invertebrate phyla have a fossil record that extends into the late Neoproterozoic before the Cambrian. Sponges (click for image) have been recognized as early as 580 million years, cnidarians (click for image--the group includes jellyfish and anemones) are present among the Ediacaran animals at around 555 million years, and the stem groups (see discussion below) for some other phyla were also likely part of the Ediacaran communities.

Defining the Cambrian “explosion” is not as straightforward as it might seem. Although there was clearly a major burst of evolutionary innovation and diversification in the first 20 million years or so of the Cambrian, this was preceded by an extended period of about 40 million years during which metazoans (multicellular animals) arose and attained critical levels of anatomical complexity. The Ediacaran saw the appearance of organisms with the fundamental features that would characterize the later Cambrian organisms (such as three tissue layers, and bilaterally symmetric bodies with a mouth and anus), as well as the first representatives of modern phyla. The base of the Cambrian is not marked by a sharp dramatic appearance of living phyla without Precambrian roots. It is a subjectively defined point in a continuum. The Cambrian “explosion” appears to have had a “long fuse.”

Notes

1. Morris, J.D., 2008, The Burgess shale and complex life, Acts & Facts 37 (10): 13.
2. Meyer, S.C., M. Ross, P. Nelson, & P. Chien. 2003. The Cambrian explosion: biology's big bang. Pp. 323-402 in J. A. Campbell & S. C. Meyer, eds., Darwinism, Design and Public Education: Michigan State University Press, Lansing, p. 326.
3. Meyer, S.C., M. Ross, P. Nelson, & P. Chien. 2003. The Cambrian explosion: biology's big bang. Pp. 323-402 in J. A. Campbell & S. C. Meyer, eds., Darwinism, Design and Public Education: Michigan State University Press, Lansing, p. 333.
4. Rozanov, A.Y., 1984, “The Precambrian-Cambrian boundary in Siberia,” Episodes 7: 20-24. Rozanov, A.Y., and A.Y. Zhuravlev, 1992, “The Lower Cambrian fossil record of the Soviet Union,” IN J.H. Lipps and P.W. Signor (eds.), Origin and Early Evolution of the Metazoa: Plenum, New York, p.205-282.
5. Bowring, S.A,, J.P. Grotzinger, C.E. Isachsen, A.H. Knoll, S.M. Pelechaty, and P. Kolosov, 1993, “Calibrating rates of Early Cambrian evolution,” Science 261: 1293-1298.
6. Gradstein, F.M., J.G.Ogg, A.G. Smith, et. al., 2004. A Geologic Time Scale 2004. Cambridge University Press.
7. Amthor, J. E.; J.P. Grotzinger,; S. Schröder, S.A. Bowring, J. Ramezani, M.W. Martin, and A. Matter, 2003, "Extinction of Cloudina and Namacalathus at the Precambrian-Cambrian boundary in Oman". Geology 31: 431–434.
8. Landing, E., A. English,and J.D. Keppie, 2010, “Cambrian origin of all skeletonized metazoan phyla - Discovery of Earth’s oldest bryozoans (Upper Cambrian, southern Mexico),” Geology 38: 547-550.

I’m not sure it’s possible to be unaware of environmental issues in 2010. After all, a Nobel Peace Prize helped bring attention to the issues of human impact on climate; recycling efforts are now ubiquitous in many areas of the country; and large corporations have invested billions in “greening” their products and production.

Why, then, do the roles of government and individuals in our stewardship of the earth seem so contentious? Sure, it’s tough to weigh uncertain scientific projections with economic impacts, tougher still to create precautionary environmental standards, particularly in a global economic crisis. And the widely publicized errors in the report from the Intergovernmental Panel on Climate Change don’t help; neither does the news of e-mail exchanges between top scientists working on climate research. Each has added fresh energy to debates about the environment from the halls of Congress to Facebook posts.

But this April as we mark the 40th anniversary of Earth Day, we’d do well to remember it as a day that, since its inception, was successful because of its remarkable grassroots response. Ever since, we’ve all become aware of the daily choices we encounter where there really should be no debate, situations where we could all do our part.

My young sons, for instance, have incredible enthusiasm for recycling, probably because they imagine the recycling truck magically rejuvenating their exhausted juice can for them. When I realized they didn’t quite understand the process, my initial leaning was to correct it; but then I wondered what might happen if we all adopted a similar zeal.

Perhaps their understanding is closer to the big picture on which we need to focus. How can we tackle the major issues facing our world if we do not enthusiastically surmount the ordinary?

Aluminum, for instance, is the most abundant metal on earth. Its abundance, though, was not always recognized, hence the crowning point of the Washington Monument being made of such a “rare and precious metal.” But it’s not a pure element in nature; it’s combined with others such as oxygen. Removing these other elements to produce pure aluminum is one of the most energetically costly processes taking place daily on our planet. So recycling aluminum not only prevents unnecessary volume in landfills but provides an estimated 95 percent energy savings over new production.

And although water covers the majority of our planet, only about three percent of the world’s water is fresh with only a third of that in liquid form. Yet we can’t live without it. Some estimate that within the next 15 years, 1.8 billion people will live in regions where water is scarce.

As New Englanders pump the spring rains from our basements, it may be hard to appreciate the value of this resource. Nevertheless, perhaps the best explanation for relatively limited media focus on global water issues is that there simply is no viable alternative. We cannot substitute another chemical for H2O.

So although heavy rains or shortages create challenges, maintaining water purity is crucial. Many pollutants are dangerous even in minute quantities – parts-per-million and lower levels. The destructive environmental and human health impact of water pollution from such sources as improper recycling of electronics in developing nations requires our attention and action. We can’t afford to under-appreciate this vital resource.

Which might be why the American Chemical Society, the world’s largest scientific society, held its conference last month with the theme “Chemistry for a Sustainable World.” Thankfully, the focus was due to strong interest in the scientific community and particularly in the younger generation of scientists. Along with colleagues and students, I attended the ACS meeting to participate in presentations, collaborate with other scientists, and help with green chemistry workshops. And I was encouraged by what I saw. Each interaction reinforced what we’ve already been teaching and observing: that the next generation of scientists and stewards—today’s students—are quick to embrace a ‘green’ vision.

That’s good news for the Earth, and of course, for those who see caring for it as an extension of their faith. Though some might want to separate the spiritual from the material, the mandate from our Creator is clear: he saw what he’d made and it was very good.

So apart from all the debates, one thing we can all agree on, especially as we enjoy the beauty of nature’s rebirth with spring’s arrival, is that the resources of our world matter. And this Earth Day can only be happy if we continue to value and invest in that which we’ve been given.

The bones in the limbs of all land vertebrates are remarkably similar. Feel around your upper arm, you'll only find one bone in there -- the humerus. Now move to your lower arm. If you're thorough, you will find two bones -- the radius and the ulna. As you continue down to the wrist, there is a whole set of little bones that attach to the metacarpals of the hand and the phalanges of the fingers and thumb. If your dog is nearby, see if he will let you continue your experiment with him. His bones are arranged a little differently, but the setup is the same. This pattern is remarkably consistent in land vertebrates. Even marine mammals like whales have a humerus, then a radius and an ulna followed by smaller bones. Darwin noted this consistency in his book On the Origin of Species. He writes, "What can be more curious than that the hand of a man, formed for grasping, that of a mole for digging, the leg of the horse, the paddle of the porpoise, and the wing of the bat, should all be constructed on the same pattern, and should include similar bones, in the same relative positions?"

It would be fun to watch Darwin read a couple of pages from the book Your Inner Fish by paleontologist Neil Shubin. Shubin studies fossils of vertebrates that lived at the time of transition from water to land. As he began his project, Shubin knew that amphibian fossils were abundant in 365 million year old rock formations, but totally absent globally in formations older than 385 million years. So he and his colleague, Ted Daeschler, decided that if they were to find the intermediates between fish and amphibians, they would need to look for fossils in exposed rocks that were about 375 million years old. A simple search through a geology textbook told them only one rock formation would meet their criteria perfectly. This formation was in northern Canada and was formed by sedimentation in a river delta.

After a six-year-long hunt from 1998-2004, Shubin and his team unearthed a "fish" very different than anyone had ever seen before. They had isolated a transitional organism with many characteristics of the land animals that became abundant 10 million years later, but it also had many characteristics of fish that lived in the period just before.

The book is a fun read, and is perfect for all who truly seek to understand God's method of creation. Here's why Darwin would have loved the story though: Shubin predicted the characteristics of a transitional species, the age of the rock formation, the type of environment in which it would be found (a river delta) and the geographic location (northern Canada) likely to have these fossils. He and his team then went out and searched for six painstaking years -- scanning the landscape inch by inch -- until they found it. It was a transitional organism with a variety of interesting features such as a neck, which was new to vertebrate life, and scales, which were an old feature. It had a rib cage with new features that came to characterize land animals, and it had interesting limbs described in meticulous detail. Just like you and your dog, the organism had the same key bones in the right place: the humerus, the radius, the ulna, some of the bones of the wrist and even primitive bones of the foot.

As beautiful as this story is, it does not end there. Unlike Darwin, we now know how the specific bones of the limb are built in an embryo, and we know why the pattern is so similar among the various land vertebrates. There is a set of genes that produces signals in a developing embryo. The hox D family of genes becomes active at specific locations in a developing limb, and bone is made.

What this means is that one group of cells in the expanding "limb bud" gets the signal, "make bone here." Further toward the tip of the limb bud, two blocks of cells receive the same signal, "make bone here." These two blocks of cells respond by making the radius and ulna. A little bit later and further toward the tip of the limb bud, a second wave of expression of the hox D signal is active. "Make bone in this region too," the signal says. The reason we all have the same pattern is that the hox D signaling pattern is very similar in the limb buds of the embryos for all land vertebrates. It can be tweaked to give variation in structure, but the basic pattern is virtually always present.

So what about the fins of fish? If fins gave rise to limbs in evolutionary history, one might expect they would have hox D gene expression which resembles that of limbs but would be different in a fairly significant way. The shark provides the best example; it has bones at the base of its fin. And, sure enough, in a shark embryo there is a wave of expression of the hox D genes in fin development just like in land vertebrates. Sharks don't have tiny bones that might correspond to our wrist, hand and fingers, so there are significant differences in hox D gene expression at the tip. However, the signaling pathway was already present in the fins of fish. The signal that says, "make bone here," was expressed in fish at the exact same location where limbs appear in land vertebrates. The transition had already begun as fish developed fins. At the most significant level, fins and limbs share important features.

I have been a biologist for a long time, and I hope I never stop getting shivers in my spine when I think about the beauty of how we come to know things in biology. Biologists make predictions, then they go out into the field or the lab to see if their predictions hold up. When hundreds of predictions of this sort are fulfilled, a theory reaches the point where it becomes certain, at least on a broad level. And that is where we are with evolution.

In this space, our purpose is not so much to try to persuade as it is to explain why we are so certain God created this way. If you wish to join us as we explore the ramifications, we would love to have you with us in the coming days. If you think that all of biology has it wrong, that is your prerogative. You're still welcome to read and think along with us. A great place to start is the book by Neil Shubin--it is very accessible to the general audience regardless of science background. Once you've read that, irrespective of what you personally believe, you'll understand why most Christian biologists view evolution as being God's way of creating life's diversity. It is my prayer that you may even see why the beauty in all of this draws us to our knees in worship.