Human Origins Update: Harvard Scientist and <i>New York Times</i> Reporter Get the "Plug Evolution Memo"...Sort of - Evolution News & Views

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Human Origins Update: Harvard Scientist and New York Times Reporter Get the "Plug Evolution Memo"...Sort of

What a difference a month, and a couple likely internal memos, can make. Last month I discussed the fact that newly reported Homo erectus fossils predated fossils of "Homo" habilis, meaning that habilis could not possibly have been an evolutionary link between the Australopithecine apes and our genus Homo. When the press covered that story, Harvard biological anthropologist Daniel Lieberman was quoted in the New York Times stating that those fossils "show 'just how interesting and complex the human genus was and how poorly we understand the transition from being something much more apelike to something more humanlike.'" It's a fascinating admission, and I wrote at the time, "Daniel Lieberma[n] apparently did not get the memo about refraining from making statements that might lead to doubts about evolution." The same could have also been said for the NY Times' article's author John Noble Wilford, who in that same article wrote, "Other paleontologists and experts in human evolution said the discovery strongly suggested that the early transition from more apelike to more humanlike ancestors was still poorly understood." I can imagine that both Wilford and Lieberman have subsequently received possibly non-fictitious memos reminding them "Don't question evolution to the public, plug evolution to the public!", because both are now defending our knowledge of human evolution in articles that just came out this week. What a difference a month makes!

Lieberman's public rhetoric has changed a lot in the last few weeks. Rather than viewing the ape-to-human transition that as "poorly ... underst[oo]d," he now apparently states, also in the New York Times, that "new discoveries further highlight the transitional and variable nature of early Homo." Yet regarding one of these "new discoveries" he recounts in his recent Nature article, the team of scientists who published the original study discussing this "new discover[y]" publicly admitted, "we know nothing about how the human line actually emerged from apes." Indeed, Lieberman himself admitted in his recent Nature article that, "When viewed up close, however, the Australopithecus-Homo transition has always been murky." Thus, we have yet another retroactive confession of Darwinist ignorance: they concede the lack of knowledge on a certain point only after some new allegedly "transitional" fossil is found.

NY Times' reporter John Noble Wilford's reversal in rhetoric is even more striking. Keep in mind that he originally reported that "Other paleontologists and experts in human evolution said the discovery strongly suggested that the early transition from more apelike to more humanlike ancestors was still poorly understood." But consider the highly different tune sung by his most recent article: "Other paleoanthropologists said the discovery could lead to breakthroughs in the critical evolutionary period in which some members of Australopithecus, the genus made famous by the Lucy skeleton, made the transition to Homo." Apparently last month, "other paleontologists" said human evolution was "poorly understood" and now the "other paleontologists" are finding "breakthroughs in the critical evolutionary period." What a difference a month makes! I think Wilford got the memo.

Additionally, it's not clear if Dr. Liebermen entirely absorbed the memo to "plug evolution," as he still writes in Nature: "The fossil record of human evolution is like a pointillist painting: one sees a different picture close up from when one stands back." In other words, don't expect too many details about evolution: Paleoanthropology has a bunch of dots, and we simply have to step back and imagine the connections between the dots. Do these new fossils connects the dots leading from ape-like species to our genus Homo?

According to Wilford's NY Times article, these newly reported fossils, "had brains not much larger than those of a chimpanzee" and "[t]he small body size and small craniums, the upper limbs, elbows and shoulders were more like the earliest habilis specimens." Of course habilis's skeleton has been recognized as highly ape-like, so these features all appear very ape-like. Why do they claim this species is transitional? Supposedly, it's all in the legs.

According to the Figure 3 in the Nature report, the femoral length is like that of a human or a gorilla (Fig. 3b). The tibial mediolateral distal width is like that of a chimp, human, or bonobo. Figure 3a reports that the tibia length is quite similar to that of a gorilla but different from that of humans. (Figure 3 also reports the length of an arm bone, as the humeral length resembles that of a human or perhaps a chimp (Fig. 3b).) Finally, the fossil footbones that were discovered are reported to have some features that are like human feet, and others that are closer to the feet of modern apes.

For those claiming this is clearly a species evolving into humans, a few troubling facts emerge from these data: This species lived millions of years after the supposed split in the lines that led to apes, and humans, respectively. I cannot be faulted for hoping that if there is an evolutionary story to be told here, this fossil would tell me whether it was evolving towards a modern ape, or a modern human. Yet these leg and foot bones in many respects resemble modern apes as much as they resemble modern humans. I cannot be faulted for being skeptical of the claim that these species were necessarily evolving towards modern humans. Is it possible these scientists are anthropomorphizing this find by assuming that it's evolving towards humanity?

Also, as noted, this species supposedly represents species that were transitional from Australopithecines to Homo erectus. Let's revisit the dimensions of the leg bones to find out where this species falls. Figure 3 in the paper reports no tibia finds for the australopithecines, so there is no data there to assess. But the chart does place these new fossils squarely between australopithecines and Homo erectus with regard to femoral length. That fits their thesis. But modern humans, gorillas, and chimps also fall right in between erectus and the Australopithecines with regard to femoral length. Again, the question must be asked, do these data show that this species is evolving towards apes, or humans? Perhaps the dots are too few and far between to tell a clear story here.

Finally, according to the currently reported data, these new fossils can't be transitional between the Australopithecines and the genus Homo. The new fossil finds were dated at 1.77 million years. Yet Homo erectus itself has been dated at 1.9 million years of age, a point conceded by Lieberman's article. Thus, it is impossible that these fossils themselves were actually transitional between the Australopithecines and Homo erectus.

In short, these are interesting new finds: Above the waist, they appear to be extremely ape-like. Below the waist, they seem to resemble modern apes as well as resembling modern humans. Yet this species post-dates the human-ape split and is being touted as a species that was evolving into a modern human, not a modern ape. What's going on here? I like Lieberman's characterization of the state of things: "murky." Maybe I just need to take the "pointillist" approach to paleoanthropology: take a step back and imagine all the lines connecting these highly fragmented and blurry dots, and hope not for too many details.