As a final installment in my “Texas Hold ‘Em” series calling the bluffs of Texas evolutionists, I’d like to highlight one section from Discovery Institute’s rebuttal to Ronald Wetherington’s Testimony before the Texas State Board of Education (TSBOE). Wetherington, who is a professor of anthropology at SMU, testified extensively to the TSBOE about human evolution, his area of expertise. Wetherington stated regarding human origins that we have “arguably the most complete sequence of fossil succession of any mammal in the world. No gaps. No lack of transitional fossils. … So when people talk about the lack of transitional fossils or gaps in the fossil record, it absolutely is not true.” But a close look at the evidence, as reported in the mainstream scientific literature, shows that it is Wetherington’s talk that is “not true.” As a preliminary example, a 2004 book by leading evolutionary biologist Ernst Mayr stated that “The earliest fossils of Homo, Homo rudolfensis and Homo erectus, are separated from Australopithecus by a large, unbridged gap” and therefore we are in a situation “[n]ot having any fossils that can serve as missing links.” To read the full statement calling Wetherington’s bluff, go to the section of Discovery’s response to Wetherington on his “Misrepresentations of the Evidence for Human Evolutionary Origins.”
F. Misrepresentations of the Evidence for Human Evolutionary Origins
Prof. Wetherington asserted that when it comes to human evolution, we have “arguably the most complete sequence of fossil succession of any mammal in the world. No gaps. No lack of transitional fossils. … So when people talk about the lack of transitional fossils or gaps in the fossil record, it absolutely is not true.” [Click here for original audio.] Though this is supposed to be Wetherington’s area of expertise, again we see him dramatically overstating the evidence as well as failing to acknowledge counter-opinions by experts within his own field.
Wetherington mentioned by name only three allegedly transitional fossil species. However, the quality of these alleged “transitional fossils” leaves much to be desired and their status as human ancestors is in fact disputed by some paleontological data.
The first fossil mentioned by Wetherington was Sahelanthropus tchadensis. But this fossil (also called the “Toumai skull”) is known only from one skull and some jaw fragments, and one leading researcher said “I tend towards thinking this is the skull of a female gorilla.”45 Wetherington bluffed when he told the TSBOE that we know this fossil qualifies as a transitional form leading to humans.
Indeed, leading paleoanthropologists have warned in the Proceedings of the National Academy of Sciences (USA) that tooth and and skull bones alone are insufficient to properly classify or understand a hominid species:
Rather, our results show that the type of craniodental characters that have hitherto been used in hominin phylogenetics are probably not reliable for reconstructing the phylogenetic relationships of higher primate species and genera, including those among the hominins.46
Another bluff from Wetherington came when he claimed that “Every fossil we find reinforces the sequence that we had previously supposed to exist rather than suggesting something different.” But in fact this Toumai skull, first published in 2002, provides an excellent counterexample to his wildly false assertion. Commenting on the Toumai skull in the journal Nature, leading paleoanthropologist Bernard Wood began an article by observing, “A single fossil can fundamentally change the way we reconstruct the tree of life.” He goes on to state:
If we accept these as sufficient evidence to classify S. tchadensis as a hominid at the base, or stem, of the modern human clade, then it plays havoc with the tidy model of human origins. Quite simply, a hominid of this age should only just be beginning to show signs of being a hominid. It certainly should not have the face of a hominid less than one-third of its geological age. Also, if it is accepted as a stem hominid, under the tidy model the principle of parsimony dictates that all creatures with more primitive faces (and that is a very long list) would, perforce, have to be excluded from the ancestry of modern humans.47
In other words, if we accept the Toumai skull as the stem ancestor of humans, as Professor Wetherington does, then many other alleged hominid species–including the other species mentioned by Wetherington that are discussed below–could not be counted as ancestors of humans.
Professor Wetherington stated that it “is not true” that there are gaps in the fossil record for the origin “for our own species, rather than for some others,” but paleoanthropological expert Wood states that fossils like this show “compelling evidence that our own origins are as complex and as difficult to trace as those of any other group of organisms.”48 Indeed, Harvard zoologist Richard Lewontin wrote in 1995 that
When we consider the remote past, before the origin of the actual species Homo sapiens, we are faced with a fragmentary and disconnected fossil record. Despite the excited and optimistic claims that have been made by some paleontologists, no fossil hominid species can be established as our direct ancestor.49
Again, it is clear that Wetherington is bluffing to claim there are “no gaps” in the fossil evidence for human evolution. If the Toumai skull represents a transitional fossil which allegedly plugs a “gap” and doesn’t “play havoc” with the proclaimed human evolutionary tree, then the evidence for human evolution must be quite weak indeed.
Wetherington next mentioned Ardipithecus as an alleged transitional form leading to humans–but this fossil too has highly fragmented remains, and has been called a hominid primarily on the basis of some of its teeth.50 Its extremely fragmented remains prevent paleoanthropologists from determining much about this species, including questions such as whether it walked upright.51 Paleoanthropologist Tim White has called the record of early hominids from this period, “a black hole in the fossil record,”52 and the few fossils that are known are based upon limited remains wherein it is not possible to make firm conclusions about these fossils.53
Despite the questions about Ardipithecus, Wetherington claimed that it “became Australopithecus afarensis 4 million years ago.” He based this claim (presumably) upon a paper by Tim White in 2006, but this paper starts by admitting that “The origin of Australopithecus, the genus widely interpreted as ancestral to Homo, is a central problem in human evolutionary studies. Australopithecus species differ markedly from extant African apes and candidate ancestral hominids such as Ardipithecus, Orrorin and Sahelanthropus.”54 And the evidence that allegedly made one species intermediate was its “masticatory robusticity” (in other words, its ability to chew harder stuff). This does not make for an impressive evolutionary scheme, and again this claim is based entirely upon reconstructed tooth fragments which, as noted, have been highly criticized by leading paleontologists as a form of data on which to base claims of hominid Phylogenetic relationships.55
And what about Australopithecus? Australopithecus literally means “Southern Ape,” and despite Wetherington’s claim that there is “no lack of transitional fossils,” there is a stark lack of intermediates between the ape-like australopithecines and the genus Homo. Indeed, in 2004 in his book What Makes Biology Unique?: Considerations on the Autonomy of a Scientific Discipline, the leading evolutionary biologist Ernst Mayr stated: “The earliest fossils of Homo, Homo rudolfensis and Homo erectus, are separated from Australopithecus by a large, unbridged gap. How can we explain this seeming saltation? Not having any fossils that can serve as missing links, we have to fall back on the time-honored method of historical science, the construction of a historical narrative.”56
Contrary to Wetherington’s claims that the basic evolutionary hypothesis about the human lineage is never being altered, a 1999 article in Science by leaders in paleoanthropology found that Homo habilis should be classified as an australopithecine,57 and an article titled “African fossils paint messy picture of human evolution” reported that how new fossil finds prevented Homo habilis from being part of our family tree:
The old theory was that the first and oldest species in our family tree, Homo habilis, evolved into Homo erectus, which then became us, Homo sapiens. But those two earlier species lived side-by-side about 1.5 million years ago in parts of Kenya for at least half a million years, Leakey and colleagues report in a paper published in Thursday’s journal Nature. In 2000 Leakey found an old H. erectus complete skull within walking distance of an upper jaw of the H. habilis, and both dated from the same general time period. That makes it unlikely that H. erectus evolved from H. habilis, researchers said.58
With habilis removed from our direct ancestry, what exactly is the direct ancestor of Homo linking back to the australopithecines? Two paleoanthropologists wrote in Nature in 2005 that we don’t know the direct ancestor of our genus Homo:
[An early form of Homo] marks such a radical departure from previous forms of Homo (such as H. habilis) in its height, reduced sexual dimorphism, long limbs and modern body proportions that it is hard at present to identify its immediate ancestry in east Africa. Not for nothing has it been described as a hominin “without an ancestor, without a clear past.”59
Likewise, an article in the Journal of Human Evolution stated:
The anatomy of the earliest H. sapiens sample indicates significant modifications of the ancestral genome and is not simply an extension of evolutionary trends in an earlier australopithecine lineage throughout the Pliocene. In fact, its combination of features never appears earlier…60
These authors said the origin of Homo required “a genetic revolution” where “no australopithecine species is obviously transitional.” One commentator said this shows a “big bang theory” of human origins because “[t]he first members of early Homo sapiens are really quite distinct from their australopithecine predecessors and contemporaries.”61
Contrary to this data, Wetherington asserted in his testimony that the origin of our species represents “a gradualistic evolutionary change,” despite the fact that there are clear gaps in the record. Indeed, one paper in the Journal of Human Evolution found that the origin of key features of our genus Homo was anything but gradual: “It appears from the hominid fossil record of pelvic bones that two periods of stasis exist and are separated by a period of very rapid evolution corresponding to the emergence of the genus Homo.”62
In contrast to these tentative admissions from paleoanthropologists, Wetherington makes firm and dogmatic statements that dramatically overstate the fossil evidence for human origins. Compare Wetherington’s dogmatic assertions to the following comment by an editor of Nature: “Fossil evidence of human evolutionary history is fragmentary and open to various interpretations.”63 Clearly Wetherington misrepresented the completeness of the evidence for human evolution, and there are indeed many gaps in the record of human origins.
[45.] Quoting Dr. Brigitte Senut, also stating “One of Dr Senut’s colleagues, Dr Martin Pickford, who was in London this week, is also reported to have told peers that he thought the new Chadian skull was from a ‘proto-gorilla’. ” See “Skull find sparks controversy” (July 12, 2002) at http://news.bbc.co.uk/2/hi/science/nature/2125244.stm
[46.] Mark Collard and Bernard Wood, “How reliable are human phylogenetic hypotheses?,” Proceedings of the National Academy of Sciences, Vol. 97(9):5003–5006 (April 25, 1999).
[47.] Bernard Wood, “Hominid revelations from Chad,” Nature, Vol. 418:133-135 (July 11, 2002) at http://www.nature.com/nature/journal/v418/n6894/full/418133a.html (emphasis added).
[48.] Bernard Wood, “Hominid revelations from Chad,” Nature, Vol. 418:133-135 (July 11, 2002) at http://www.nature.com/nature/journal/v418/n6894/full/418133a.html (emphasis added).
[49.] Richard C. Lewontin, Human Diversity, p. 163 (Scientific American Library: New York NY, 1995).
[50.] Y. Haaile-Selassie, “Late Miocene hominids from the Middle Awash, Ethiopia,” Nature, Vol. 412:178-181 (July 12, 2001).
[51.] See Figure 2, Bernard Wood, “Hominid revelations from Chad,” Nature, Vol. 418:133-135 (July 11, 2002) at http://www.nature.com/nature/journal/v418/n6894/full/418133a.html
[52.] A. Gibbons, “In Search of the First Hominids,” Science, 295:1214-1219 (February 15, 2002).
[53.] See Figure 2, Bernard Wood, “Hominid revelations from Chad,” Nature, Vol. 418:133-135 (July 11, 2002) at http://www.nature.com/nature/journal/v418/n6894/full/418133a.html
[54.] Tim D. White et al., “Asa Issie, Aramis and the origin of Australopithecus,” Nature, Vol. 440:883-889 (April 13, 2006).
[55.] Mark Collard and Bernard Wood, “How reliable are human phylogenetic hypotheses?,” Proceedings of the National Academy of Sciences, Vol. 97(9):5003–5006 (April 25, 2009).
[56.] Ernst Mayr, What Makes Biology Unique?: Considerations on the Autonomy of a Scientific Discipline, pg. 198 (Cambridge University Press, 2004).
[57.] Bernard Wood and Mark Collard, “The Human Genus,” Science, Vol. 284:65-71 (April 2, 1999).
[58.] Associated Press, “African fossils paint messy picture of human evolution; who was our ancestor’s ancestor?,” International Herald Tribune, at http://www.iht.com/articles/ap/2007/08/08/america/NA-GEN-US-Human-Evolution.php
[59.] Robin Dennell & Wil Roebroeks, “An Asian perspective on early human dispersal from Africa,” Nature, Vol. 438:1099-1104 (Dec. 22/29, 2005) (internal citations removed) (emphasis added).
[60.] Hawks, J., Hunley, K., Sang-Hee, L., Wolpoff, M., “Population Bottlenecks and Pleistocene Evolution,” Journal of Molecular Biology and Evolution, 17(1):2-22 (January, 2000).
[61.] “New study suggests big bang theory of human evolution,” (January 10, 2000) at http://www.umich.edu/~newsinfo/Releases/2000/Jan00/r011000b.html
[62.] F. Marchal, “A New Morphometric Analysis of the Hominid Pelvic Bone,” Journal of Human Evolution, Vol. 38:347-365 (2000).
[63.] H. Gee, “Return to the planet of the apes,” Nature, Vol. 412:131-132 (July 12, 2001).