PNAS has published a paper, Limits of long-term selection against Neandertal introgression. It’s from a preprint which I blogged this summer. What are the major takeaways here?
It’s been about 10 years since the draft Neanderthal genome was published. At around that time everyone realized that there was archaic introgression into the modern human genome. More precisely, reticulation in the human phylogeny was a major thing in the time scale of 50,000 years and earlier.
But there were a lot of details to clear up. For example:
- Did % Neanderthal admixture vary outside of Africa?
- Was there really only one single admixture?
- Has natural selection shaped the proportion of Neanderthal genetic material in our genomes?
The reason the new paper above is interesting is that they used differences between Neanderthal populations (of different relatedness to the source into moderns), as well as modeling different demographic scenarios through simulation, to show that:
- Neanderthal % is Europe is no different than Asia, rather, there is West Eurasian gene-flow into Africa
- Selection against Neanderthal genes seem to have occurred very early, and little later one
- Selection seems to be strong around regulatory elements
- The lack of variation due to basal Eurasian admixture indicates they may have been part of the admixture
This is not the final world. Rather, it illustrates that though the first pass result stands, a lot of details are being worked out, and that this dynamic field is sensitive to the samples available and theoretical frameworks that leverage those samples.