Natural selection and language genes in humans

In this study we construct lists of candidate genes for articulate language. Analysis of coding regions of over 100 candidate genes for the effects of natural selection (directional episodic selection and relaxed/intensified selection) in the various lineages of primates (thirty-four nonhuman primate species, plus Homo sapiens Neanderthals and Denisovans) revealed a burst of increased selection effects on neural genes at the node leading to the Homo sapiens-Neanderthal-Denisova triad, followed by bursts of selection effects on neural genes related to language in both the Denisovan and Neanderthal lineages. Those latter increases in involvement of neural genes in Neanderthals and Denisovans can be contrasted with the missing or slight response to selection on those same genes in the H. sapiens lineage. The genes involved in these bursts can mostly be classified as involved in synapse structure and maintenance. We develop a hypothesis for how synaptic efficiency could be related to language acquisition in these lineages.