Teshima, K. M. | bioRxiv Science

bioRxiv2026

Polygenic evolution towards a morning chronotype in modern humans

Chronotype is a behavioural phenotype, and its phenotypic trend is considered to change at higher latitudes. In the current study, we performed a polygenic assessment of chronotype trend using associated single nucleotide polymorphisms identified by a genome wide-association study. We found that the phenotypic trend towards morningness increased drastically during the migration of anatomically modern humans above 20 degrees north. Furthermore, two types of latitudinal selection of morningness alleles contributed to establishing the trend towards the morning chronotype at higher latitudes. We propose that the trend towards morningness is stronger in present-day modern humans living above 20 degrees north than in Neanderthals.

evolutionary biology↗

bioRxiv2024

Global adaptive evolution involved in neuroticism and educational behaviors through the spread of anatomically modern humans

A cumulative process of cultural evolution occurred globally alongside the spread of anatomically modern humans (AMHs). This process of evolution was likely accompanied by global changes in mental and behavioral phenotypes, resulting in cultural differences between AMHs and Neanderthals. Globally, selective increases of frequencies were detected in alleles, which contributed to the suppression of neuroticism and advanced learning. This finding indicates that neuroticism was suppressed and learning behaviors developed through the global spread of AMHs. It suggests that global adaptation to psychosocial stress occurred, which contributed to cumulative cultural evolution by increasing cooperative learning. A comparison of phenotypic trends at the population level indicates that such globally occurring adaptive evolution, entailing neuroticism suppression and increased learning behaviors has been more significant in AMHs than in Neanderthals. However, adaptive evolution toward greater intelligence was more significant in Neanderthals than in AMHs. These findings suggest that mental traits involved in cultural development evolved differently in AMHs and Neanderthals, and that learning behaviors such as cooperative learning, rather than intelligence, played an important role in AMH evolution.

evolutionary biology↗