Study Links Human Right-Handedness to Bipedalism and Brain Size

A new study published April 27 in PLOS Biology examined why right-handedness occurs in roughly 90 percent of humans across cultures. Researchers collected data from 2,025 individuals in 41 monkey and ape species and analyzed handedness against factors including tool use, diet, habitat, body mass, social organization, brain size, and locomotion.

The study concluded that humans do not follow the same patterns observed in other primates. Dr. Thomas A. Püschel of Oxford’s School of Anthropology and Museum Ethnography said the work is the first to test several major hypotheses for human handedness in one framework.

Researchers stated that the shift to upright walking freed the hands for tool use, gestures, and fine motor tasks. They wrote that this change created selective pressures favoring stronger hand preferences. Larger brains that developed after bipedalism further reinforced the rightward bias, according to the study.

The authors noted that no left-dominant human society has been documented. Professor Chris Venditti at the University of Reading and co-author Rachel M. Hurwitz contributed to the analysis of evolutionary relationships among the species studied.