There’s an interesting recent paper on the genetic basis of the changes we see in domestication – and the extent to which humans exhibit similar genetic changes. domesticated species end to have depigmentation, floppy ears, shorter muzzles, curly tails, smaller teeth, smaller cranial capacity, neotenous behavior, reduced sexual dimorphism, docility, and more frequent estrous cycles: the ‘domestication syndrome’. There is reason to think that this syndrome arises from a mild deficit of neural crest cells.
They talk about a number of loci that look to be involved in such changes in in anatomically modern humans, and show evidence of selection (when compared to archaic humans like Neanderthals and Denisovans). They discuss a number of such genes and gene pathways.
I noticed something interesting about one of the genes mentioned [ ERBB4] & the other genes it interacts with. ERBB4 (the neuregulin receptor) negatively regulates ERK, which plays a critical role in neural crest development and regulates neuronal gene expression in both the neocortex and hippocampus. Closely related is BRAF, upstream of ERK. BRAF interacts with YWHAH (selected in dogs), PPP2CA (selected in horses), while ERBB4 shows selection in anatomically modern humans and cattle. Upstream of BRAF, SOSI has been selected in domesticated foxes.
ERBB4 binds with NRG1, NRG2, NRG3, NRG4, and ADAM17. NRG2 was selected in cats, cattle, and dogs. NRG4 was selected in cattle, NRG3 in AMH.
But there’s more: there is evidence for recent regional selection of variants in the ERBB4 pathway [ work from Joe Pickrell] . ERBB4 shows strong signals of selection in all non-African populations, NRG3 shows strong signs of selection in West Eurasian populations, while NRG1, NRG2, and ADAM17 show signs of selection in East Asians.
It is not necessarily the case that all humans are equally domesticated, or became domesticated in exactly the same way. We know that some populations split off as long as a quarter of a million years ago. Although the earliest known AMH skeletons already show signs of the domestication syndrome ( the childlike flat face), their skulls were a good deal more robust than those of any people today. Probably the process has continued over time, quite possibly it even accelerated in dense agriculture agricultural populations in the Holocene. But that wouldn’t have taken the same course everywhere.
Members of populations that have gone further down the path of self-domestication should be easier to enslave.
For all I know, some populations moved into new environments that effectively reversed these selection pressures (feral humans] .
And with rapidly improving genetic technology, we could probably create truly feral humans.