Defending the Tale of the Whale
Is the story of whale evolution in trouble? An expert walks through recent claims.
In discussions of the evidence for evolution and common descent, the origin of cetaceans (including modern whales, dolphins, and porpoises) has become a frequently highlighted case study, and rightly so. In my own personal story, it was learning about the burgeoning fossil record of the earliest cetaceans, documenting their transition from life on land to life in the water, that inspired me to pursue graduate studies in evolution and paleontology. I was fortunate to be accepted into Philip Gingerich’s lab at the University of Michigan, which allowed me to conduct research on the fossil creatures that got me interested in paleontology in the first place. At the time, I didn’t know much more about fossil whales than what I could glean from books and magazines. But since then I have been able to study these fossils firsthand at museums around the country and even prospect for and excavate whale fossils in the desert in Wadi Al-Hitan, Egypt. This research has allowed me to dive deeply into the work that has been carried out by other researchers studying early cetaceans, oftentimes confirming their interpretations, but sometimes leading me to question the conclusions of prior studies. I have witnessed vigorous debates between well-respected researchers at odds over how best to interpret certain data. I have seen gaps of our knowledge in this transition, illuminating new avenues for future research and discovery. But throughout all of this, I have continued to see the accumulation of compelling evidence from a wide variety of fields that corroborates the origin of cetaceans from terrestrial ancestors.
Given the prominence of cetaceans as a sort of poster child for large-scale evolutionary change, it has also become a common target for detractors of evolutionary theory. On many occasions, I have received skeptical emails and letters from well-meaning Christians, often sharing copies of articles or book chapters that purportedly detail how the evolutionary origin of cetaceans lacks any scientific validity. The first time I received one of these letters, I started reading through the article this person had included. Within just a few pages, I had noted at least a dozen mischaracterizations, misunderstandings, and outright errors, which left me frustrated—not only as a scientist whose research area was being maligned, but also as a Christian. As I wrestled with the compatibility of modern science and Christian faith as a young person, I found it difficult to sort through the arguments put forth by the most prominent voices in the “creation versus evolution” debate, mainly because I didn’t have a good sense for what arguments might contain half-truths, misperceptions, or outright falsehoods. Thankfully, I had trustworthy Christian scientists in my life who could help me sift through these arguments with utmost care and humility—something that I have tried to carry on in my own work in helping students and church members think through issues of science and faith.
It is in this context that I recently watched a series of videos produced by the Discovery Institute (DI). Near the end of April, they unveiled an animated video questioning whether whale evolution was good evidence for Darwinian evolution. I considered writing a detailed critique of the video, but due to other responsibilities that were amplified by the COVID-19 pandemic, I simply did not have the time. However, several others posted video responses in May (here and here, for example), which prompted the DI to post a rebuttal video at the beginning of July. This generated yet another response video, which was followed by a third video from the DI in early August. In sum, I find the three DI videos to be very troublesome.
First and foremost, I find the overall tone of the videos to be disheartening. In some sense, I understand the desire to create videos that are humorous, but the manner in which these videos are produced often reduces serious scientific claims to little more than silly jokes and analogies. (“You wanna hear something silly?”, the first video begins.) While the tone does improve a bit in later videos, many segments basically implore the audience to make light of the argument without considering it on its merits or discerning whether the argument is being presented fairly and accurately.
This leads to my second major issue with these videos: their portrayal of the scientific data and arguments. These videos are rife with inaccurate portrayals and misconceptions about the fossil record, as well as technical subfields like biostratigraphy and phylogenetic systematics. For example, they outrageously claim that it “is common practice in evolutionary analysis to ignore where species actually show up in the fossil record and place them wherever makes Darwinian sense.” Many of these issues have been discussed in the other response videos online, so I am not going to spend time breaking them down here. But it struck me how many of the DI videos’ critiques were focused specifically on biologist and blogger Jerry Coyne’s description of whale evolution in his book Why Evolution Is True. I’ll admit that I sometimes find popular science depictions of whale evolution to be problematic. They can be overly simplistic and sometimes even contain mistakes—though many of these mistakes would mostly go unnoticed if you’re not a specialist on fossil whales. But if your goal is to counter a scientific claim through valid data and sound reasoning, then it behooves you to engage a fair and accurate account of the argument, not a simplistic strawman. Not only does doing this constitute good science, but as Christians, I believe doing things this way is what we are called to do.
This whole situation helps to remind me of the importance of being as fair and accurate as possible in my discussions of evolutionary science and Christian faith, particularly so that I do not mislead the general public and Christian laypeople about scientific claims or theological positions.
Let’s look at a couple of examples. One specific scientific issue that appears in all three DI videos relates to a fossil discovered in Antarctica that purportedly upends the proposed timeline for cetacean evolution. It represents a partial jawbone that appears to belong to a basilosaurid archaeocete, a representative of the first fully aquatic cetaceans. When it was initially described, this discovery made waves because Reguero et al. (2012) dated this fossil at 49.5 million years old (Ma), which would make it roughly contemporaneous with many of the very oldest, semiaquatic archaeocete cetaceans. In other words, this new fully aquatic fossil looked “too old” to fit in the evolutionary timeline. The first DI video brought up this fossil to argue that it basically threw the fossil record of early cetacean evolution into disarray. But they ignored subsequent work by Buono et al. (2016), including Reguero and all of the other authors on the 2012 paper, that amended these dates based on additional analysis and evidence. The second and third DI videos spend an extended amount of time discussing the Buono et al. paper and other studies, arguing that most studies converge on the older dates and that Buono et al. prefer a few less reliable studies with younger dates simply to confirm their evolutionary presuppositions. This prompted me to take a deeper dive into the relevant studies to see how accurate the video’s claims were. What I found was troubling.
I know that the next few paragraphs get a little technical, but it is important to dig into the details just a little bit. I will do my best to summarize the issues in an understandable way, but if this is not your cup of tea, feel free to scroll down to the conclusion.
The second DI video shows an animation that illustrates the range of ages that other studies have proposed for the geological formation in which this particular whale fossil was found. In several cases, I had trouble lining up the ages shown in the video with the ages actually proposed in the various studies. For other papers, the dates illustrated in the video often constitute ages proposed for the entirety of the geological formation (or large sections of it) rather than simply the level at which this particular fossil was found. For example, the video suggests that Dutton et al. (2002) propose an age range of 55–46 Ma, despite the fact that the paper itself estimates the age of about 47.5 Ma for the specific layer in which the basilosaurid jaw was found. Likewise, the dates the video illustrates for Douglas et al. (2014) span from 49–42 Ma, despite the fact that the layers below the level with the whale jaw (which must be older) are aged to be between 45–38 Ma in the paper itself. So it seems that many of the ages portrayed in the video are not necessarily fair representations of what the studies themselves proposed.
Jackson Wheat posted a response to the second DI video, which works through several more examples of issues like those noted in the previous paragraph. This prompted the DI to produce a third video, which addresses some of these problems but makes other mistakes. For instance, this most recent video notes that Bijl et al. (2013) provide information about the ages of dinoflagellate microfossils that are abundant in the geological layers in question, which would help to date the rocks. But it misrepresents what the data actually mean. It lists several different species with associated ages, rightly noting that all but one are associated with ages that are early Eocene (more than 48 Ma) or even older. But it is important to realize what these dates are. They are not different age estimates for the layer with the whale jaw; they are the ages of the first appearance of those species in the fossil record. Yes, many of these fossils are known from rocks even older than the ones in question, but they can persist for millions of years afterwards. Thus, it is vital to recognize the age of the youngest of the microfossils in the relevant rock layer, because this places a lower bound on how old the rocks can be. The video does highlight the age of the youngest microfossil, though it takes umbrage with the specific age used by Bijl et al. In so doing, it fails to recognize that the age favored by these authors is based on a newer age calibration from work that supersedes previous studies. The video goes on to suggest that Douglas et al. (2014) make an error in dating this key species of dinoflagellate fossil, citing publications from 2003 and 2004 to bolster that claim. But the video doesn’t recognize that Douglas et al. are working off of more recent research as well, which contrasts with the age estimate proposed by the older studies.
Finally, these videos do a poor job of fairly presenting the various scientific claims about the disputed age of these layers. They make it seem like most reliable studies prefer the older dates, with just a few rogue unreliable studies positing younger dates. But in reality, there have been many studies over the years that have favored the younger ages for these units for a variety of different reasons. The third video concludes by quickly moving through a series of additional papers that purportedly support the older dates for these rocks. However, it fails to recognize that many of these papers accept those older dates uncritically, simply using dates posited by earlier studies. It also does not highlight any recent papers that prefer the younger ages, nor does it point out that many studies also recognize the uncertainty here. Even when they prefer one set of dates over the other, many authors are typically quick to discuss the fact that there is ongoing contention about the ages of these specific rock layers. A recent paper by Amenábar et al. (2019) nicely discusses the disagreement.
With Honesty, Humility, and Faithfulness
So am I, as a paleontologist who studies early cetacean evolution, concerned that this fossil jaw from Antarctica is causing my study system to fall apart? No, I’m not. I have heard from colleagues that dating these particular geological units in Antarctica is extremely challenging, which helps to explain why no true consensus has developed about their precise ages in the past 30+ years. I also think there are good reasons to remain skeptical of some of the older proposed dates, and I suspect that with further study, a consensus will develop that these units are younger than some have proposed. But this is how science is meant to work. There is clearly more research to be done here, both in dating the strata that yield Eocene whale fossils in Antarctica and in understanding the whales that are found there. Remember: the fossil in question here is a partial jawbone with a fragmentary tooth. While these elements do appear most similar to some of the oldest fully aquatic whales, we still do not have the rest of the skeleton, which would tell us a lot more about its swimming capabilities, ecology, and way of life. In fact, it could possibly help to clarify details in the transition from a semiaquatic way of life to a fully aquatic existence, an area of study that is in need of more complete skeletons to elucidate the details about how this occurred.
But, to me, this whole situation helps to remind me of the importance of being as fair and accurate as possible in my discussions of evolutionary science and Christian faith, particularly so that I do not mislead the general public and Christian laypeople about scientific claims or theological positions. Many Christians in science have become convinced of the veracity of evolutionary theory and common descent due to a wide range of different types of evidence that converge on that explanation. Are there things we don’t yet know? Absolutely. Are there some bits of evidence that are inconsistent with our favored explanations as they stand in 2020? Sure, and those areas deserve more study so that we can discern whether we have misunderstood those pieces of evidence or we need to adjust our current explanatory models. But throughout all of this, it is vital for us as Christians to pursue this work with honesty, humility, and faithfulness, recognizing our own limitations as fallible human beings who are not above making mistakes, and striving to use our God-given talents and passions to pursue study of the world around us in a way that brings glory to our Creator. May we all be grateful for the privilege it is to not only understand how the world around us works day in and day out, but also the processes that God has utilized to bring us to this point across the vast eons of time.
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