How much did admixture depend on social cognition in the human past?

Here is a funny idea. Those of you that keep up with human evolution studies know that hybridization is a hot topic: as time passes by, we learn of more and more introgression events in the human deep past. Most people, even outside academic circles, are aware of the Neanderthal and Denisovan introgression. What seems to be the case is that the picture is way more complicated the more we know, including bidirectial admixture, potential unkown species admixture events between extinct human species, and overall a myriad of possibilities that we are discovering only now.

So, as it’s natural, I’ve though about hybrids in biology more and more lately: what hybridization means, how it manifests in species and what causes it. I recently saw this paper in Twitter dealing with correlates of hybridization in birds. It turns out sociality and migration and the biggest factors to take into account, according to the authors:

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There are a number of theories about how social cognition has changed over the course of human evolution, with a host of competing theories that might actually be complementary with each other. People have proposed changes in various hormones (such as dopamine) or the glutamatergic system, to name a couple broad directions, and of course there is no consensus about when did these changes happen exactly – though the archaeologocial record helps a bit here, and I think most people agree the groundwork was done by the time of Homo erectus, with some part of them potentially falling later on in history, as proposed by people in the research group I’m in right now (meet my friend and colleague Tom, for example, for one perspective on this).

I was wondering, in this direction, if the finding would replicate in human species, and how much can we infer of social cognition and the long/short term social bond dychotomy by looking at the introgression history of our species – and maybe viceversa, though of course it might be harder to infer social cognition traits in the deep past. In an increasingly complex species landscape, where frontiers between the branches of the human tree get more and more blurry, this is almost a begged question.

My impression is that the migration bit might explode in a couple years, or maybe even before, with the emergence of a trend towards spatial-aware Population Genetics, something I’m very much looking forward to. I wonder what will be possible to infer about the interplay between ecological adaptation, migration, social cognition and admixture.