We overlapped with Neanderthals for thousands, in some places maybe tens of thousands of years. Probably interacted on territorial borders with them for as long. And yet still, we only seem to have produced successful hybrids with a single line or tribe of Neanderthals. Although apparently multiple times with that particular group over a timespan of thousands of years.
And I am unsure how long we overlapped or interacted with Denisovans, but it seems reasonable to suppose that it was for a long time and over quite a large area too. Yet still, Denisovan genes are mostly confined to limited groups of people, generally in southeast Asia and the pacific. American Indians completely lack Denisovan DNA. Both hint that the Denisovan introgression was quite late, although I expect not being in the initial Out-of-Africa wave meant no founder effect for the Denisovan DNA.
However, in both cases, there seems to have been serious barriers to interbreeding. An I would postulate that they are unlikely to have been cultural or behavioral in nature, at least on our side. Humans tend to... have a very wide preferences in terms of sex-partners, to put it mildly. We are not, as a rule, a choosy people. If we live next to another people for any amount of time, fornication will occur. Given that we overlapped for thousands of years with the other peoples, and that such overlap was therefore likely to involve multiple human cultures and behaviors, I doubt the barriers can have been cultural.
It seems possible that the barriers were biological. But the length of separation with the others -maybe 26 000 generations- seem short for us to develop such barriers. And the whole "There was one lot we had kids with a number of times -but no-one else" just seems downright peculiar.
Any thoughts?
And I am unsure how long we overlapped or interacted with Denisovans, but it seems reasonable to suppose that it was for a long time and over quite a large area too. Yet still, Denisovan genes are mostly confined to limited groups of people, generally in southeast Asia and the pacific. American Indians completely lack Denisovan DNA. Both hint that the Denisovan introgression was quite late, although I expect not being in the initial Out-of-Africa wave meant no founder effect for the Denisovan DNA.
However, in both cases, there seems to have been serious barriers to interbreeding. An I would postulate that they are unlikely to have been cultural or behavioral in nature, at least on our side. Humans tend to... have a very wide preferences in terms of sex-partners, to put it mildly. We are not, as a rule, a choosy people. If we live next to another people for any amount of time, fornication will occur. Given that we overlapped for thousands of years with the other peoples, and that such overlap was therefore likely to involve multiple human cultures and behaviors, I doubt the barriers can have been cultural.
It seems possible that the barriers were biological. But the length of separation with the others -maybe 26 000 generations- seem short for us to develop such barriers. And the whole "There was one lot we had kids with a number of times -but no-one else" just seems downright peculiar.
Any thoughts?