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What, Another “Rewrite” of the Human Origins Story? How About a Rethink, Instead?

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Sometimes predictions are not only fulfilled but over-fulfilled. Writing here recently at Evolution News (Bechly 2017a), I listed seven major discoveries in paleoanthropology that have made 2017 an annus horribilis for the established scientific consensus on human evolution. I ended, however, with the remark that “2017 is still not over. Maybe further surprises are ahead.” I was right – more surprises were indeed just over the horizon. A month later, alleged hominin teeth were reported from the Miocene of Germany that are older than the oldest African hominins and thus contradict the well-known “Out of Africa” scenario (Bechly 2017b).

Only a few days after that, other paleontologists vehemently disputed the new findings, doubting that one of the teeth belongs to a primate at all (Greshko 2017, Hecht 2017). This, of course, was without having seen the actual fossils. Getting rid of such problematic finds would be very convenient, so doubts remain on either side of the story.

Meanwhile, paleoanthropologists could barely catch their breath, as further published research casts further doubt on the conventional wisdom about human origins. Lo and behold, as New Scientist announces, “Ancient skull from China may rewrite the origins of our species” (Barras 2017). What, again?! Come on, the calls for rewriting our understanding of human evolution are coming now not just annually (Qiu 2016) but on a monthly basis. This is getting ridiculous. How often do you hear that fundamental ideas in chemistry or physics have to be “rewritten”? What does this tell us about the status of evolutionary biology? Let’s have a look at what the new discovery is all about.

Actually, the fossil itself is no new discovery at all. It is a fossil human skull that was found 1978 in China within a loess terrace near a small village in Dali County of Shaanxi Province (Brown 2016). It is one of the most complete early human crania from eastern Eurasia. However, the dating was somewhat controversial, and so was the interpretation of the Dali skull as either an untypical Homo erectus or an archaic Homo sapiens. It has sometimes even been linked to the Denisovans, but without much evidence for this.

Now a new study by Athreya & Wu (2017) not only offers a final resolution of the dating of the Dali skull, as Middle Pleistocene with a radiometric age of 258-268 thousand years, but also presents a detailed multivariate assessment of the craniofacial morphology in comparison to other Middle Pleistocene Homo specimens from Asia, Africa, and Europe. Even though the authors consider no taxonomic allocation for the Dali cranium as appropriate at this time, their results strongly suggest that the fossil is morphologically intermediate between Chinese Pleistocene Homo erectus and later Chinese Homo sapiens, reviving the long-buried multiregional model (Qiu 2016). In that model, Homo sapiens did not evolve exclusively in Africa, then migrate to Asia and there replace Homo erectus, but instead originated either independently or coordinately in Africa, Eastern, and Western Eurasia. While the Dali cranium is clearly archaic in general appearance, it strikingly shares characteristic features with modern East Asian humans, but not so much with modern African and European humans. This runs right up against the “Out of Africa” hypothesis.

Newsweek features the discovery with the headline, “Ancient hominin skull from China suggests that humans didn’t evolve just from African ancestors” (Medrano 2017). Even Barras (2017) cautiously admits in his New Scientist piece:

Most anthropologists believe, based on fossil evidence, that our species arose in Africa around 200,000 years ago. What’s more, genetic studies of modern humans indicate that we are all descended from a single population that left Africa within the last 120,000 years and spread around the world. This African group is the source of all modern human genes, barring a few gained by interbreeding with other species like Neanderthals. However, the Dali skull may not fit this story. [Emphasis added.]

The so-called “braided stream network model of reticulate gene flow,” favored by the authors of the new study, basically implies that all fossil Homo taxa belonged to the same interbreeding biospecies as modern Homo sapiens. That fits surprisingly well with the observation by critics of Darwinian evolution that the fossil record does not show a gradual development from apes to humans, but instead either clear apes or clear humans, with a distinct morphological gap between these two groups of fossils.

So, that makes eight important discoveries this year that all were announced as challenging established theories of human origins, thus requiring a major rewrite of the story. One is tempted to ask the question, how many more major rewritings do we have to endure until a major rethinking is considered? The current consensus is refuted by more and more evidence. But in spite of all this conflicting evidence, the holy cow of Darwinian evolution of humans from ape-like ancestors may not be questioned. Why? Because that would challenge the ruling scientific paradigm of naturalism. God forbid!


Photo credit: New York Zoological Society [Public domain], via Wikimedia Commons.