*Update Jan. 2016* It has come to my attention that this post is being linked to from a white nationalist forum as supporting the idea that “whites were never in Africa – it’s another white liberal lie.” I know white nationalists are not particularly known for their skills in reading comprehension, but I still want to point out that this isn’t the case at all. How you get that out of “non-Africans have a 4% Neanderthal admixture in their DNA, and Melanesians also have Denisovan admixture” is beyond me. If you’re a white nationalist, you don’t care, but if you are generally interested in what effect the archaic species admixtures have on the populations that have them, can take a look at Milford Wolpoff and Shauna McNally’s comments to this post and Wolpoff’s more recent research. For more on what this means in terms of racial genetics, you listen to Wolpoff’s bloggingheads interview with Razib Khan here. In other news, if you’re a white nationalist, you make me sick. *End Update*
Although it seems that the big news in paleoanthro this week is the unveiling of Austrolopithecus sediba fossils and not Milford Wolpoff at all, interest in paleoanthro naturally begets more interest in paleoanthro, so I figured why not talk about – and apologise to – Milford Wolpoff?
Milford Wolpoff is a professor of anthropology at the University of Michigan, and the most prominent proponent of what is known as the “regional evolution hypothesis“. Regional evolution is one of the ideas for origins of modern humans worldwide. Much as its name suggests, the hypothesis proposes that the evolution of homo sapiens from earlier homo species happened in different regions of the world. This is not to say that the evolution events were separate, but the evolutionary paths in the various regions, the hypothesis says, were partly dictated by the archaic homo that were already present in those regions (for example, the Neanderthals in Europe). It is usually contrasted with the recent african origin theory, which posits that anatomically modern homo developed once, and then went on to replace all other hominins. The specifics usually cited involve a start in Eastern Africa, after which the sapiens replaced all the archaic homo species in Africa, and then migrated out of Africa between 150,000 and 100,000 years ago, stuck around North Africa and the Middle East for a while, and then, about 50,000 years ago expanded into Asia and Europe, completely eliminating and replacing the homo species that previously occupied those regions.
Morphologically and archaeologically, the two theories were somewhat competitive, although most evidence did point to a recent African origin. But it was genetics that really sealed the deal for Out-of-Africa in the 80’s. In a seminal paper in 1987, Allan Wilson, Rebecca Cann and Mark Stoneking traced out a common ancestor for all living humans using mitochondrial DNA (mtDNA). Mitochondrial DNA is DNA that is unrelated to the DNA of the human host, and so is not strongly subject to environmental selection, and varies slowly and at predictable rates. It is also passed on matrilinearly, so by comparing mtDNA of two subjects, you can discern a time when the common matrilineal ancestor of the two people lived. Wilson Cann and Stoneking showed a “mitochondrial Eve” living about 160,000 years ago, and the first split being between the Khoisan and the non-Khoisan peoples. This was considered a slam-dunk for the recent out of Africa hypothesis.
Yet, though greatly marginalised, Wolpoff persevered in championing regional evolution. But the only other people in the field who agreed seemed to be either his students or his ex-students, giving the hypothesis the whiff of almost a cult, and an unconvincing one at that (to me, at least). In the piece of writing I put the most effort into so far in my life, I wrote that this idea should be dismissed “out of hand” and specifically didn’t provide a citation just to show off how uncontroversial I thought this claim was. I would even insult the idea for no reason when talking about something else. for instance naming “Milford Wolpoff vs. anthropologists who aren’t crackpots” as a rivalry alongside “Habs vs. Leafs” and “Beatles vs. Stones”.
The professor of my first biological anthropology class (Brian Chisholm) held the opinion that neither theory was entirely correct, and the truth lay somewhere between the two. This seemed to me mealy-mouthed and ridiculous. How could there be a middle ground between regional evolution and total replacement? What, did the moderns invading Europe have “just a little bit” of sex with the Neanderthals, I scoffed? Well, turns out, current best science seems to suggest that that’s exactly what happened. This knowledge is thanks to Svante Pääbo’s group at the Max Planck Institute for Evolutionary Anthropology in Leipzig who sequenced the genome of the Neanderthal and the Denisovan hominin. It’s pretty mind-blowing that this could be done, actually. But the upshot is that around 4% of non-Africans’ genomes are shared with Neanderthals, which suggests that little bit of sex I was talking about. And with Densiovans, it’s even stranger: 4 to 8% of their genes are shared with Melanesians (who by the way live nowhere near Siberia, and are sometimes blond despite being dark-skinned), but not with other humans. And now, Razib Khan writes of new research where modelling of African DNA from modern populations suggests an admixture from archaic homo as well. It turns out that, perhaps not in details, but Milford Wolpoff was, in a lot of ways, right.
Wolpoff once claimed – and I am possibly misquoting here because I can’t find a reliable source on the internet, but the quote is good enough that I can’t let it be unsaid in clearly the only thing on Milford Wolpoff I’ll ever write – “Data do not speak. I have sat in rooms with data for hours and didn’t hear a thing.” And yet these data seem to speak pretty loudly in favour of at least a mild form of regionalism to go along with the out-of-Africa theory. So, professor Wolpoff, my apologies, and for the rest of us, a reminder that things that we choose to consider settled questions in science are sometimes anything but.
Milford Wolpoff, and Shauna McNally, a former student, have clarifying replies in the comments. Be sure to read them!