How do Theistic Evolutionists Explain the Fossil Record and Human Origins?
Our recent book Science and Human Origins responds to a variety of arguments for human-ape common ancestry, including prominent arguments from theistic evolutionists. In six recent articles (see the links at right), I have argued that the fossil record does not support the evolution of ape-like species into human-like species. Rather, hominin fossils generally fall into two distinct groups: ape-like species and human-like species, with a large, unbridged gap between them.
How have theistic evolutionists dealt with the topic of human origins? Unfortunately, most simply accept, adopt, and promote the standard Darwinian story, offering virtually no critical analysis whatsoever. We saw this in the book, where theistic evolutionist Ronald Wetherington, an anthropology professor at SMU, gave an uncritical endorsement of the standard claims of human evolution. (His arguments for human evolution were so strongly stated that they probably went much further than what many non-theistic evolutionary paleoanthropologists would dare say.)
Another good example is what the principal blogger covering human origins at BioLogos, Dr. James Kidder, did last year did in a series on human origins. His series is a good read and quite a competent presentation of the standard Darwinian evolutionary view of human origins -- which no doubt reflects Dr. Kidder's extensive training and experience with this issue. But it accedes 100% to the standard Darwinian story of human origins with essentially no critical analysis whatsoever. But how solid is the evidence behind Dr. Kidder's view, and are there credible paleoanthropologists who doubt key parts of the orthodox story?
My recent series has discussed and cited numerous scientific papers which raise points that challenge the standard Darwinian account of human origins. Conspicuously, virtually none of these credible scientific challenges are mentioned in Dr. Kidder's posts for BioLogos. His series, though well written, capitulates entirely to the orthodox Darwinian view and presents that to BioLogos readers as if it were all there is to say on this issue. End of story.
What's a "Transitional Fossil"?
In Dr. Kidder's first post in the series, he asserts, in response to a comment I made, that "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."
Now, the actual comment I made and that he quoted says nothing of the kind, because that is not my position at all. On the basis of strict evidence -- not "faith" -- I argue in Science and Human Origins that in the context of human evolution good examples of transitional fossils are conspicuously lacking. But I am open to the possibility that transitional fossils might exist, and in other contexts, I do think there are some plausible examples of transitional fossils. For example, some fossils show transitional features in the horse series (even though there's not much in the way of large-scale evolution going on there). But as my series on human origins has demonstrated, the fossil evidence shows a clear break between human-like and ape-like species, which is not bridged by transitional fossils. This is not merely my own opinion. My article cites multiple evolutionary scientists who are acclaimed experts in the field and who make this same basic sort of claim.
Dr. Kidder's BioLogos post tried to argue that I misunderstand the meaning of "transitional fossil." This is a common and characteristically unfounded charge from Darwinian evolutionary biologists. They make the accusation because it takes the focus off the problems the fossil evidence poses for Darwinian evolution, and puts it on Darwin-critics. Advocates of Darwinian evolution also redefine what counts as "transitional," so that the term becomes nearly meaningless. Here's what's going on:
We see that the phrase "transitional form" is used in two different ways. The "soft" definition of "transitional" implies that an organism merely needs to bear features that are representative of a potential intermediate -- even if the fossil itself was not a direct transitional form. Under the hard definition of "transitional form," a stronger claim is made that this organism actually was a real-life lineal intermediate between two taxa, a direct transitional form.
As evidence that this soft/hard distinction is used, for example, when some early tetrapod tracks were first reported in early 2010, Nature's Editor's Summary said: "The finds suggests that the elpistostegids that we know were late-surviving relics rather than direct transitional forms, and they highlight just how little we know of the earliest history of land vertebrates" (emphasis added). The qualified term "direct transitional form" is a nod to the writer's understanding that there is in fact a "hard" definition of a transitional form, and a "soft" definition, and that some fossils don't meet the hard definition. What some people call a "transitional form" isn't necessarily a "direct transitional form."
Kidder framed his attack in the standard way, writing:
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.There's much to say in response. First, note the logical irony: when transitional forms are found, that's evidence for evolution, but if you point out that the fossil record is lacking transitional forms, then you have created a "straw man." It's "Heads I win, tails you lose."
Second, Kidder's argument -- a common one -- essentially puts Darwinian evolution in an unfalisifiable position with respect to the fossil record. If transitional fossils confirm evolution, but a lack of transitional fossils don't disconfirm it (but rather, simply suggest the record is poor), is it even possible to test Darwinian evolution by looking at the fossil record?
Third, not all paleontologists agree with Kidder that the lack of transitional fossils is simply the result of the unsophisticated (and all-too-easy) excuse the fossil record is poor. Consider what paleontologist Niles Eldredge and paleoanthropologist Ian Tattersal (who are both committed evolutionists) co-wrote in a book on human origins:
The record jumps, and all the evidence shows that the record is real: the gaps we see reflect real events in life's history -- not the artifact of a poor fossil record.Fourth, despite the fact that I am Dr. Kidder's foil, I can hardly remember ever using the term "missing link" when I wasn't quoting someone else -- often quoting a Darwinian evolutionary scientist. So Kidder is not only wrong to suggest I do use that term, but he's also wrong to suggest that evolutionary scientists never use it. In fact, the term appears in textbooks and even the occasional scientific paper. (See here for just a few of many examples.)
(Niles Eldredge and Ian Tattersall, The Myths of Human Evolution, p. 59 (NY: Columbia University Press, 1982).)
Fifth, when scientists don't use the term "missing link," that is not always because they don't want to use it but rather can be because media coaches for the Darwin lobby like Eugenie Scott tell them not to use it publicly. Don't believe me? Read reports on Scott's media-coaching advice yourself: One Nature blogger reports on a panel where Dr. Scott advised scientists not to use the term "missing link":
I thought I'd curate here some of the amazing advice they [Eugenie Scott and others on a panel] shared which will be useful to anyone writing about evolution or discussing it, especially in religious communities. ... Don't try to use the word "missing link" even though it is always sexy. This conveys a wrong impression that scientists are missing a certain fossil to actually prove evolution happened. The truth is, every newly discovered fossil of a creature we didn't know of before IS a missing link. There is no need to hype a story unnecessarily.What we see here is an admission that scientists often want to use the term "missing link," but don't out of PR fears that the word "missing" will remind people that the fossil record often doesn't document evolutionary transitions.
In any case, I guess a lot of scientists didn't get that memo. A quick search of science storehouses like Nature, Science, ScienceDaily, and Pubmed gives literally hundreds of hits reflecting common usage of the term "missing link" in the scientific literature (and press statements from mainstream scientists).
But this is all an aside. I appreciate exactly what Kidder is saying. I really do. If you define "transitional form" in a soft enough way, so that neither temporal placement nor phylogenetic relationship matters any more, then it becomes very difficult to disprove claims that a fossil was "transitional." It's a wily rhetorical tactic, designed to make Darwin-skeptics look ignorant while simultaneously taking the focus off the lack of actual (e.g. hard) transitional forms in the fossil record. Dr. Kidder complains that ID proponents define such forms "in such a way that none could ever be found," when in reality it's Darwinian evolutionists who define transitional fossils so that they must, by definition, be found in abundance--even if they weren't necessarily part of an evolutionary transition. Thus we see the Nature blogger quoted above saying absurd things like "every newly discovered fossil of a creature we didn't know of before IS a missing link." Or, we see Dr. Kidder making the less-absurd (though similarly inspired) claim that "[t]he human fossil record, in fact, is replete with transitional forms," as well as:
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.Kidder would have no troubling finding some authorities who agree with him. But there are also credible authorities who disagree -- especially with regard to those specific fossils. For example, in my series we've seen there are credible authorities who believe that "one of the most critical" areas of the human fossil record lacks transitional forms--specifically, "the transition from Australopithecus to Homo."
Likewise, my series has also cited authorities who would disagree with Dr. Kidder's claim that Ardi "was advanced in the human direction," in the sense of developing bipedal locomotion, and who would sharply dispute his assertion that Ardi represents "a phenomenal example of a transitional form in the human fossil record." Other experts would dispute the claim advanced by Kidder that the australopithecines show clearly "transitional characteristics." In particular, many doubt the claim that Lucy's morphology was "perfectly intermediate between the ape position and the human position."
Indeed, even Kidder admits: "Unfortunately, the path from Australopithecus to early Homo is shrouded in mystery, with no clear hominin form considered decisively to be the progenitor." True! But then why does Kidder feel the need to so completely capitulate to the view that humans evolved from Australopithecus? He claims that ID proponents take it as an "article of faith" that transitional forms don't exist, but it seems that some Darwinian evolutionary scientists take it as an "article of faith" that they do exist, and that the standard Darwinian story of human origins is true.
My point is not that Dr. Kidder is unequivocally wrong or that he's uninformed. Hardly. He's welcome to hold and express his opinion, and his series is a highly competent presentation of the standard Darwinian evolutionary account of human origins. Rather, I want to respectfully note that the standard story of human evolution -- to which BioLogos's principle blogger on this topic fully capitulates -- is not the only scientifically credible position out there. When you dig into the technical literature, many parts of the standard story turn out to be based upon very weak evidence. In short, there are strong scientific reasons to dispute the claim that humans evolved from ape-like precursors. Is it acceptable to point this out?
Arguments Full of Gaps
While Dr. Kidder maintains that fossil record of human evolution is "replete" with transitional fossils, he also has a fallback argument ready-and-waiting to explain away those instances where we don't find transitional fossils: gaps in the fossil record. In another post responding to me on paleoanthropology, Dr. Kidder responds to my comment that "Darwin's defenders argue that their theory 'predicts gaps in the fossil record.'" After I observed that evolutionary theory predicts gaps, he acknowledges that Darwinian evolutionists anticipate "gaps" in the record. It seems that on this point we don't have much to disagree on. Kidder thinks he can find something: he criticizes me for supposedly misunderstanding the cause of those gaps. Here's what he writes (while continuing to defend his expectation of "gaps"):
Evolutionary theory doesn't predict gaps. Geology predicts gaps. There is simply no way short of a miracle that we would have completely fossil rich preservation sites for every conceivable depositional environment. Such an expectation misunderstands how geological processes work. Expecting such a fossilized environment misunderstands how taphonomy works.Of course I never suggested anything remotely like we should always have "completely fossil rich preservation sites for every conceivable depositional environment." It's not clear if Kidder is suggesting I said this, but if he was, then he put words in my mouth I would never say.
While geology may also predict gaps, my point here, however, is that Kidder is wrong to say "Evolutionary theory doesn't predict gaps." There are plenty of reasons to understand why modern evolutionary theory predicts gaps.
Thomas J. M. Schopf makes this inextricably clear in his introduction to Eldredge and Gould's famous 1972 chapter in Models in Paleobiology which first introduced punctuated equilibrium ("punc eq") to the world. Schopf explained that Eldredge and Gould's model "views such gaps as the logical and expected result of the allopatric model of speciation." (p. 82) This is because, as Donald Prothero explains, the allopatric model predicts that evolutionary change is more likely to become fixed in small populations:
In 1954, Mayr proposed the allopatric speciation model. According to this idea, new species usually do not arise within the main body of a population, because the genetic exchange between organisms rapidly swamps any new variations. Instead, small subpopulations which are genetically isolated from the main population are more likely to change, because an evolutionary novelty has a much better chance of dominating a small population than a large one.But of course smaller poulations that are shortlived have a much smaller chance of leaving fossils behind. Eldredge and Gould explain this in their famous 1972 paper:
(Donald Prothero, "Punctuated Equilibrium at Twenty: A Paleontological Perspective," Skeptic, Vol. 1(3): 38-47 (Fall, 1992).)
The theory of allopatric (or geographic) speciation suggests a different interpretation of paleontological data. If new species arise very rapidly in small, peripherally isolated populations, then the expectation of insensibly graded fossils is a chimera. A new species does not evolve in the area of its ancestors; it does not arise from the slow transformation of all its forbears. Many breaks in the fossil record are real.In another famous paper Gould wrote on punc eq, he also gave a biological justification for why we should find gaps in the fossil record. Again, Gould argued that most macroevolutionary change ("speciation") takes place in relatively small and shortlived populations, dramatically decreasing the odds that transitional forms will be fossilized:
(Niles Eledredge and Stephen Jay Gould, "Punctuated Equilibria: An Alternative to Phyletic Gradualism," in Models in Paleobiology, p. 84 (Freeman, Cooper & Company, 1972).)
Speciation, the process of macroevolution, is a process of branching. And this branching ... is so rapid in geological translation (thousands of years at most compared with millions for the duration of most fossil species) that its results should generally lie on a bedding plane, not through the thick sedimentary sequence of a long hillslope.So a proper understanding of punc eq and allopatric specation shows that "gaps" supposedly flow right out of their biological model of evolution--not merely geology. According to the theory, the period of transition is so "rapid," that a record of it is unlikely to be fossilized. Under their model of evolution, it's not the case that "Evolutionary theory doesn't predict gaps."
(Stephen Jay Gould, "Is a new and general theory of evolution emerging?," Paleobiology, Vol. 6(1): 119-130 (1980).)
The problem with their model, of course, was that it requires too much change too fast. Gould and Eldredge acknowledge this criticism in a 1993 review paper in Nature:
Evolutionary biologists have raised a number of theoretical issues from their domain of microevolution ... [and] continued unhappiness ... focuses on claims that speciation causes significant morphological change.I discuss these problems in more detail in "Punctuated Equilibrium and Patterns from the Fossil Record." But the point is this: if you read what proponents of evolution by "speciation" argue, it's clear they try to explain that their theory of evolution predicts, on the basis of geology and biology, that we should find gaps in the record--right when speciation happens. In other words, they claim we won't find fossils forming right at the very point where the vast majority of evolutionary change takes place. Isn't that convenient!
(Stephen Jay Gould and Niles Eldredge, "Punctuated equilibrium comes of age," Nature, Vol. 366:223-227 (November 18, 1993).)
While proponents of punc eq have their biological arguments for "gaps," they often come off as an excuse. Would you believe someone who claimed to capture fairies and Leprechauns on video, but when asked to produce the film, declares "well, they are on camera but they are too small or too fast to be seen"?
In any case, I doubt that Stephen Jay Gould would agree with Kidder's strong statement that "The fact that there are gaps in the fossil record has nothing to do with the fact that evolution has or has not taken place." Gould would say that it's precisely because evolution often occurs in small, shortlived populations, that these macroevolutionary events aren't recorded in the fossil record, and we see "gaps." While geology surely plays a major role here, Kidder's statement reflects an inaccurate description of how evolution by allopatric speciation is thought to work.
As we'll see in the next section, Dr. Kidder has a long-standing history of attacking me personally, making false claims about my lack of training in biology, and attacking my knowledge of this issue. Readers can decide for themselves whether the person attacking the other's expertise in biology, or the person being attacked, expresses a correct understanding of why many evolutionary biologists anticipate gaps in the fossil record.
How Will Dr. Kidder Respond?
It will not surprise me if Dr. Kidder decides to respond to this article. If he does, I hope he'll do so in a civil manner. In the past, when writing on his personal blog, BioLogos's primary blogger on human evolution has called folks here at Discovery Institute (myself included) things like "ignorant or mendacious" or "intellectually dishonest" (or sometimes just "dishonest"), and has accused us of "distorting and lying " (or sometimes just "lying"). We see Kidder, stating things like "Discovery Institute has no intention of treating the data in an honest fashion" where we are "engaged in hucksterism and propaganda" and "[t]he rot goes all the way to the top." He concludes when writing about us: "Good riddance and bad rubbish." He also calls us "juvenile" and "immature." Though he uses a more civil tone when writing on the BioLogos blog, this is how BioLogos's principal spokesman on human origins behaves on his personal blog.
Dr. Kidder also been known to respond by attacking the credentials of people he disagrees with. In one post, he writes about me, "Is the DI's principle [sic] spokesman a biologist? No, he's a lawyer with no training in biology." Aside from the fact that I don't think anyone here ever considered me "DI's principal spokesman," his claims about my training aren't true. In fact I have much university-level training in biology, including a dozen or so courses at both the undergraduate and graduate levels that directly covered evolutionary biology, all taken while studying at University of California at San Diego and Scripps Institution for Oceanography. How does the fact that I later went to law school (and then became a lawyer) negate that training?
In any case, if Dr. Kidder responds to Science and Human Origins and my most recent commentaries human origins, he may try this same kind of response. In fact, that's what he's already done. Kidder's wrote a brief comment on Science and Human Origins, where his approach was to attack my credentials, proclaim he doesn't need to read the book, and defer to Paul McBride:
Instead of getting a palaeoanthropologist to write a chapter on human origins fossils, they get a LAWYER who has no training in the field to do it. I don't need to read Casey Luskin's arguments against human evolution in Science & Human Origins. I have read them before. They haven't changed -- even in the face of new evidence. I intend to read the book but for now I am content that Paul McBride has identified the principle problems. (emphases in original)It's hard not to notice that Kidder attacks my qualifications to write on this subject, but gives an unqualified endorsement McBride's critique of my chapter on the fossil record--even though McBride isn't a paleoanthropologist and states that he himself "lack[s] any degree of expertise" in physical anthropology. This certainly seems like a double-standard. For my part, I'm not attacking anyone's qualifications to comment on this subject, and don't object to McBride, Kidder, or most anyone writing about it. (David Klinghoffer has already written a nice response to Kidder's form of credentialism that has proven common among critics of Science and Human Origins--see David's article: "When You Can't Answer the Argument, Attack the Credentials of the Person Offering It.")
But why does Kidder make his responses so personal? The answer is given to us in another short commentary on Science and Human Origins from Kidder, where he acknowledges how emotional he gets on this subject:
This is a book I clearly need to pick up and read, although I am quite certain it will just make my blood boil to do so.It seems that based upon past experience, Dr. Kidder's way of responding to Discovery Institute is to become emotional and intensely personal in his arguments. This path is his choosing, but it's unfortunate -- it would be nice if there could be a civil and serious substantive conversation on this topic.
(Readers can read my responses to Paul McBride and decide for themselves if he has made a good case against my thesis. See "Double Standards and a Single Variable: A Response to Paul McBride's Review of Fossils in Science and Human Origins," "Read Your References Carefully: Paul McBride's Prized Citation on Skull-Sizes Supports My Thesis, Not His," or "McBride Misstates My Arguments in Science and Human Origins.")
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.A few examples of technical papers and textbooks that use the term "missing link" include:
- Peter H. Raven, George B. Johnson, Kenneth A. Mason, Jonathan B. Losos, and Susan R. Singer, Biology, 9th ed. (New York, NY: McGraw Hill, 2011), 425;
- Jingxia Zhao, Yunyun Zhao, Chungkun Shih, Dong Ren and Yongjie Wang, "Transitional fossil earwigs - a missing link in Dermaptera evolution," BMC Evolutionary Biology, 10 (2010): 344.
- Michael Coates and Marcello Ruta, "Nice snake, shame about the legs," Trends in Ecology and Evolution, Vol. 15:503-507 (December, 2000).
- Matt Kaplan, "Archaeopteryx no longer first bird," Nature News (July 27, 2011).
- Rex Dalton, "Fossil primate challenges Ida's place," Nature, 461, 1040 (2009).
- John Whitfield, "Almost like a Whale," Nature News (September 20, 2001).
- Ann Gibbons, "Missing Link Ties Birds, Dinosaurs" Science, 279: 1851-1852 (March 20, 1998).