Some teeth in China:
I find it disconcerting when something comes out that upends something I have been leaning on. It’s hard to play the game when they keep moving the playing field. Yes, I know. I’m not a member of the brotherhood of scientists and I’m not supposed to be playing; no team, so to speak. Well here’s a new one.
I had read, and did for the sake of argument believe that modern humans arose in Africa, passing through a bottleneck some sixty (call it fifty to seventy) thousand years ago and about that time some of them migrating outward eventually to the whole world and even into space.
Now they think there is evidence for the teeth of modern humans being found in a cave in China, the date of the teeth being something like 80 to 12o,000 years old. The work was led by Wu Liu and Xin-Jie Wu the Chinese Academy Institute of Vertebrate Paleontology and Paleo-anthropology in Beijing. (Ann Gibbons, First Modern Humans in China Science vol. 350 no. 6258 October 16, 2015 page 264) Now you may think there’s not much to choose between 70,000 and 80,000, considering how long ago that was and the improbability of finding any one tooth. But I had gotten rather fond of 60,000. (I was rather fond of Pluto before they revoked its planted status and take grim satisfaction in learning just how interesting it is from a probe launched before the demotion.)
If there was indeed a bottleneck in the human population around then, it has been attributed to the Toba supervolcano catastrophe around 69,000 to 77,000 years ago followed by a long volcanic winter and a very much longer climate cooling.
Well in fact the whole bottleneck has been questioned. (Hawks J, Hunley K, Lee SH, Wolpoff M (January 2000). "Population bottlenecks and Pleistocene human evolution". Molecular Biology and Evolution 17 (1): 2–22.) although the Wikipedia article asserts that this reference indicates the possibility of a drop of the population to something like 2,000 over a period of 100,000 years.
I’m saying 60,000 years ago and a bottleneck below 1,000. Everybody else in our species, like those in the Chinese cave, did not thread the eye of that particular needle. The Neanderthals did, of course. They got along well with cold climate.
So the world keeps shifting under my feet. I would dearly love to say, “Look. We’re all the same species because it would take over 64,000 years for us to develop a new and different species,” but that’s not made any easier if we really have been a species for 120,000 years. And then there is the question of the Khoisan people, pygmies and Hottentots, who may have never left Africa, and some who went back, including I much suspect, (on informal observation) Bantu.
All most difficult. Perhaps I should stick with what I know.
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