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Denisovans, Neandertals, Anthropology 101

Update July 2012: This was one of the first efforts to comprehensively review anthropology textbooks for fall 2011 with regard to Neandertal admixture findings and Denisovan discoveries. There were several updates posted (search on “Denisovans” for more), and two related content sections: Denisovans, Neandertals, Archaics as Human Races and More Mothers than Mitochondrial Eve.

Fall 2011 is the first full academic year featuring splashy press reports of admixture between modern humans and both Neandertals and Denisovans. These are exciting times for the human origins segment of Anthropology 101, but we need to go beyond current textbooks. We also need to defend against racist interpretations of admixture data.

The textbooks are deficient

In 2011, not a single four-fields textbook mentioned the 2010 Denisovan finds, and only one–the Scupin and DeCorse textbook that became available in July 2011–discusses the Neandertal interbreeding.

Obviously revisions have to be in the pipeline long before print editions emerge. Of course we cannot blame textbooks for not having up-to-the-minute currency–after all, even peer-reviewed articles in the geneticist community are playing catch-up: “the shifting landscape has caught many geneticists off their footing” comments John Hawks, who predicts “a large-scale reorganization of the science of human origins is upon us.”

Nevertheless, there is the deeper problem of how textbooks have generally portrayed scientific consensus around the out-of-Africa replacement hypothesis, while underplaying, omitting or misrepresenting multiregionalism. As the balance shifts, it becomes more obvious how much of a mistake that has been, as Alan R. Templeton warned in Genetics and Recent Human Evolution (2007). Templeton’s recovery of Franz Weidenreich’s trellis is a great place to become reacquainted with gene flow.

At the end of this post I review each of the 4-field introductory textbooks, ranking them by how each can accommodate the new finds. I would not choose a textbook solely by this test, but it is an important consideration.

Racists seize new admixture data

There’s been a lot of reporting on how the Neandertal admixture is with “non-Africans.” Add how the Denisovan admixture shows up in contemporary Melanesians, and it’s the perfect racist recipe:  claiming Neandertal admixture helped non-Africans “advance” as they migrated from Africa, but then subsequent Denisovan interbreeding resulted in lower IQs for Papua New Guinea. I am not making this up–read into the comment stream on the article The paradigm is dead, long live the paradigm around comment #29.

There are several factors making this racist interpretation available. First is the reporting of Nicholas Wade, who is always so quick to play up a race-based interpretation, and who makes a big deal of how Neandertal admixture is with “non-Africans.” The final sentence of Wade’s Neandertal report is that “Neanderthals interbred only with non-Africans, the people who left Africa, which would mean that non-Africans drew from a second gene pool not available to Africans.”

Then look how that gets used in an article by biologist Sean B. Caroll on hybrids:

It now appears that 1 percent to 4 percent of the DNA sequence of Europeans and Asians, but not Africans, was contributed by Neanderthals mixing with Homo sapiens, perhaps in the Middle East 50,000 to 80,000 years ago. It is possible that some Neanderthal versions of genes enabled modern humans to adapt to new climates and habitats. (Hybrids May Thrive Where Parents Fear to Tread)

A second factor is how the scientists reporting this information are thinking about dueling evolutionary hypotheses, not public impact. Apparently long-gone are the days when multiregionalism used to compete with out-of-Africa for the least-racist trophy. Recent models and arguments, such as Vinayak Eswaran’s Diffusion Wave Model, seem to have almost nothing explicit to say about racial categorizations.

A third factor is the imbalance of power for who-studies-whom in the scientific community. Neandertal ancestry gets embraced, but I have not seen parallel pronouncements that “Denisovans Live!  I, for one, welcome my Denisovan ancestry.” Or consider the final sentences in the otherwise fascinating “Why not the Neandertals?”: “For us Europeans, the Neandertal debate is nearing resolution and the conclusion is that they are one of us. Recognizing this is a key step in the process of understanding how and why we became different” (Wolpoff et al. 2004:538). Admittedly, 2004 might have been a time when nine co-authors, all affiliated with U.S. universities, may have wished to cement ties to “old Europe.” But still.

I used to do a short song-and-dance in my Intro class about how Neandertal cranial capacities were actually larger than anatomical moderns. I was trying to banish the brutish Neandertal stereotypes, as no one wants to get caught in a Neandertal anti-defamation file. I also wanted to point out that bigger brains are not automatically better. Obviously I am not the only one: every 4-field textbook includes a similar statement about Neandertal crania. However, I will NOT be emphasizing big-brain Neandertals in fall 2011. Not with all this “non-African” stuff around.

A plea for help

The textbooks are not up to speed, and this is not a case when professors can simply provide links to newspaper articles or even the peer-reviewed studies. The newspaper articles lend themselves to racist interpretations; the peer-reviewed articles are too busy dueling against replacement hypotheses. Nor can we simply dig up Wolpoff’s work and say “he told you so.” Wolpoff concentrated on Neandertals as a source of European difference, in ways that are not all compatible with the new evidence, and in ways that are not always helpful for rebutting racist revivals.

Anthropology 101 needs a statement that will 1) summarize the findings 2) tell us what they mean for multiregional and replacement hypotheses and 3) tell us why this cannot be the basis for revamping racism. This would be best coming from real biological anthropologists.

I have written about this in sections on Denisovans, Neandertals, Archaics as Human Races and More Mothers than Mitochondrial Eve. I would be grateful for any help or comments.

Update for 2012-2013: Denisovan findings are beginning to filter into the Introduction to Anthropology Textbooks. For a review, see the Anthropology Courses section.

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