A general evolution landscape of language and cognition genes

Abstract

The polymorphism profiles of language genes (LG) display different patterns across various ancient and modern populations, leading to the speculation that cognition gene (CG) polymorphism profiles may exhibit similar trends. However, the evolutionary processes of language gene polymorphism patterns (LGPP) and cognition gene polymorphism patterns (CGPP) are likely to demonstrate distinct characteristics. In particular, it is intriguing to determine whether there is any overlap in the timing of significant changes in CGPP and LGPP over the large timescales of evolution. The potential existence of such overlap can also be assessed by examining whether the samples carrying significant changes in LGPP and CGPP are the same. This study investigated the genetic differences at 239 SNP loci in 18 language genes (LG) and 223 SNP loci in 18 cognition genes (CG) across 170 whole genomes. Principal component analysis (PCA) was used to cluster the SNP data of the aforementioned samples, and the similarity of SNP patterns between each sample was calculated from three perspectives: LG, CG, and CGLG. The basic conclusions are as follows: (1) If different positions in the PCA analysis results can essentially represent the pattern differences in SNP polymorphisms, then both language gene polymorphism patterns and cognition gene polymorphism patterns have undergone distinct stages of evolution; (2) There were significant differences in the early manifestations of language gene polymorphism patterns and cognition gene polymorphism patterns during human evolution: Language gene polymorphism patterns could not differentiate general animals, primates, and ancient human samples in the early stages of evolution, whereas cognition gene polymorphism patterns seemed to be initially divisible into two patterns, one closely resembling a group of animals and certain ancient human samples, and the other reflected in a different set of animal and primate samples. (3) It appears that samples from all five continents can be observed at every stage of evolution, suggesting that new evolving populations have always had ample time to spread across continents. (4) A quantitative comparison of the SNP profiles of 170 samples revealed that their CG and LG plus CGLG profiles indeed have 2-3 potential significant change points, and the samples carrying these significant change points has 2 common samples, namely ge1 (Georgia) and us2 (North America), implying that the most significant changes in language or cognition gene polymorphism patterns during human evolution may have occurred in some human populations in Europe/ North America.