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.

本研究构建了针对连贯言语的候选基因列表。我们对100余个候选基因的编码区域开展分析，以探究自然选择（定向间歇选择（directional episodic selection）、松弛/强化选择（relaxed/intensified selection））在各类灵长类演化支系中的作用效应，所涉物种包含34种非人灵长类，以及智人（Homo sapiens）、尼安德特人与丹尼索瓦人。分析结果显示，在指向智人-尼安德特人-丹尼索瓦人三分支的演化节点处，神经系统基因受到的选择作用显著增强；随后，丹尼索瓦人与尼安德特人演化支中，与言语相关的神经系统基因亦出现了选择作用增强的爆发式现象。上述尼安德特人与丹尼索瓦人中神经系统基因参与度的提升，可与智人演化支中这些基因对选择的缺失或微弱响应形成鲜明对比。参与上述爆发式选择过程的基因，大多可归类为参与突触结构与维持的基因。本研究还提出了一项假说，用以阐释这些演化支中突触效率与言语习得之间的关联机制。