They Are Us? News from the Primate Research Front May 11, 2010Posted by Nina Rosenstand in Nina Rosenstand's Posts, Philosophy of Human Nature, Science.
Tags: chimpanzees, DNA, homo sapiens, hybrid, Neandertals, toolmakers
Time for an update on our ongoing reevaluation of our primate cousins: here’s story #1, from the New York Times. In brief, we’ve known for fifty years that humans aren’t the only tool users, or even tool makers. Now it turns out that humans aren’t the only ones using, well, sex tools, either! One group of chimps in Tanzania does, too (which, by the way, makes it a culture, rather than instinct):
After noting that chimpanzees’ “tool kits” are now known to include 20 items, Dr. McGrew casually mentions that they’re used for “various functions in daily life, including subsistence, sociality, sex, and self-maintenance.”…
…The tool for sex, he explained, is a leaf. Ideally a dead leaf, because that makes the most noise when the chimp clips it with his hand or his mouth.
“Males basically have to attract and maintain the attention of females,” Dr. McGrew said. “One way to do this is leaf clipping. It makes a rasping sound. Imagine tearing a piece of paper that’s brittle or dry. The sound is nothing spectacular, but it’s distinctive.”
The NYT science piece by John Tierney is on the flippant side, but that doesn’t detract from the power of the report: sexual practices among apes can be local, non-inherited, taught, and culture-driven in addition to being biological. Sounds rather familiar.
And here’s story #2: Europeans and Asians are related to Neandertals, after all! Now we’ve heard for ten years that Neandertal DNA hasn’t been found in the human population, but that turns out to be false: Discover Magazine reports that, according to a study published in Science ,
Researchers from Germany’s Max Planck Institute for Evolutionary Anthropology first sequenced the entire Neanderthal genome from powdered bone fragments found in Europe and dating from 40,000 years ago–a marvelous accomplishment in itself. Then, they compared the Neanderthal genome to that of five modern humans, including Africans, Europeans, and Asians. The researchers found that between 1 percent and 4 percent of the DNA in modern Europeans and Asians was inherited from Neanderthals, which suggests that the interbreeding took place after the first groups of humans left Africa.
Anthropologists have long speculated that early humans may have mated with Neanderthals, but the latest study provides the strongest evidence so far, suggesting that such encounters took place around 60,000 years ago in the Fertile Crescent region of the Middle East [The Guardian].
So does that mean that Homo Sapiens, just having wandered out of Africa, and the waning Neandertal populations found each other attractive, dated, and intermarried? This is an issue some of us have been wondering about for decades, and what the research apparently shows is that Neandertal male DNA is present in the human population, but not female DNA. A variety of explanations have been posted on various science websites (see the links in the Discover article quoted above) , such as the very good idea that a pregnant Neandertal female would give birth with her own family, while the human mother would raise her hybrid child with the other humans, where the Neandertal genetic material would show up later. That would mean that both species adhered to the ancient matrilocal custom of the family living with the wife’s maternal relatives. But we can’t possibly know about such customs, at least at this stage.
I have another idea which I will float here: evidence of Neandertal DNA in the human population after their move out of Africa doesn’t mean that Neandertals and humans liked each other, or that they lived together as families, or that they had hybrid human-Neandertal societies. As Hemingway says in The Sun Also Rises, “Wouldn’t it be pretty to think so…” But the real story may be less friendly, and more realistic: human females may simply have been raped by male Neandertals, as part of warfare, or chance encounters. Let’s remember that rape is not a sexual phenomenon per se, but also a power manifestation. And the human females may have made it back to their home village, to raise hybrid children, or may have raised them in Neandertal captivity if we’re going to go all-out with speculations. Certainly it is also possible that Neandertal women were raped by human males (which would be somewhat harder to imagine, since those Neandertal ladies would be many times stronger than a human male, but gang rape or rendering the woman unconscious would solve that problem…), and raised human hybrid children back with their Neandertal community. But apparently there is no DNA evidence of that, if I understand the results correctly.
So is there a moral to these two stories? I think so… You decide…