They’ve managed to sequence a bit of autosomal DNA from the Atapuerca skeletons, about 430,000 years old, confirming that they are on the Neanderthal branch.
Among other things, this supports the slow mutation rate, one compatible with what we see in modern family trios, but also with the fossil record.
This means that the Pygmies, and probably the Bushmen also, split off from the rest of the human race about 300,000 years ago. Call them Paleoafricans.
They are anatomically modern: they have chins, etc. Behaviorally modern? There have been only a few attempts to measure their intelligence: what has been done indicates that they have very low IQs. They definitely talk, tell stories, sing songs: does that imply that they could, given the right environment, have developed the Antikythera mechanism or a clipper ship?
This means that language is older than some had thought, a good deal older. It also means that people with language are quite capable of going a quarter of a million years without generating much technological advance – without developing the ability to push aside archaic humans, for example. Of course, people with Williams syndrome have language, and you can’t send them into the kitchen and rely on them to bring back a fork. Is the sophistication of Bushman language – this means the concepts they can and do convey, not the complexity of the grammar – comparable with that of other populations? I don’t know. As far as I can see, one of the major goals of modern anthropology is to make sure that nobody knows. Or that they know things that aren’t so.
The minimal definition of behavioral modernity – that set of traits that exists in all of humanity, including those that are most divergent, and that are probably ancestral in anatomically modern humans – may not include much technological creativity.
Next: since we now know that generic Neanderthal and Denisovan alleles don’t fit too well with anatomically modern humans, and AMH alleles didn’t fit too well with Altai Neanderthals, it seem likely that you see the beginning of such functional divergence between Paleoafricans and everyone else. I know of one example of a European haplotype that’s a heart disease risk on a mostly-African genetic background, but not on a European background, but most such incompatibilities are probably very mild, hard to detect. It would probably take thousands of generations for a Pygmy population to lose a significant fraction of its Bantu introgression. You might be able to detect this on a few alleles, but for the most part it just hasn’t been long enough.
Culture gets forgotten, inventions get lost: any populations with a sufficiently low innovation rate probably does not advance at all, culturally. They could respond to natural selection, change in a way that increased their innovation rate… So people could continue to make Acheulean handaxes for a million years: they had to change before there could be further technological progress. Neanderthals had more sophisticated technology, but that technology changed very, very slowly compared to, say , that of humans in the upper Paleolithic. Biology keeps culture on a leash, and you can get to the end of the leash.
Some have suggested that the key to technological development is higher population: that produces more intellects past a high threshold, sure. I don’t think that’s the main factor. Eskimos have a pretty advanced technology, but there were never very many of them. On the other hand, they have the highest IQ of any existing hunter-gatherer population: that’s got to help. Populations must have gone up the Eemian, the previous interglacial period, but nothing much got invented back then. It would seem that agriculture would have been possible in the Eemian, but as far as we know it didn’t happen. Except for Valusia of course. With AMH going back at least 300,000 years, we have to start thinking about even earlier interglacial peiods, like Mindel-Riss (424-374 k years ago)