Science

...mutations in the human genome in some subset of individuals, would confer a survival advantage, and thus be subject to selection pressure and quickly move through the population.

It is now widely understood that people of European extraction contain some Neanderthal genes, a few percent apparently, and the question has arisen as to whether Neanderthals used language. Maybe they did, but if they didn't this may account for the destruction of their species. I'm not familiar with any of the details in the literature, but I am aware of the debate. It's possible therefore that when Africans arrived in Europe, where they evolved white skin under selection pressure to produce vitamin D in cold climates, they also brought the genes for language use.

It's all speculation on my part - I'm hardly an expert - but it seems reasonable.

The interbreeding of distinct populations with a different genome to "homogenize" into Homo Sapiens, which, as I read it, is the point of this paper seems to have taken place once again in Europe in the case of Neanderthals and Homo Sapiens.

I find it interesting that in a connotative sense, the word "Neanderthal" can imply "stupidity" often to people experiencing White Privilege - and I am myself a person of European extraction - when the people who most benefit from this privilege, descended from a race of human beings who set out to brutally conquer the world, Europeans, are in fact, the most Neanderthal.

It is clear that when the language genes left Africa, they spread throughout the world, a clear selective advantage, particularly when dealing with new climatic zones.