Upright Walking, Brain Growth Drove Right-Handedness

A new study led by researchers at the University of Oxford and the University of Reading suggests that the overwhelming right-handedness in Human is a result of two major evolutionary milestones: upright walking and the dramatic growth of the human brain. By analyzing data from 2,025 individuals across 41 primate species, the researchers used Bayesian modeling to test existing hypotheses. They found that once brain size and bipedal locomotion were accounted for, humans no longer appeared as an evolutionary anomaly. The study indicates that early human ancestors like Ardipithecus and Australopithecus had mild right-hand preferences, which strengthened through Homo ergaster, Homo erectus, and Neanderthal, reaching its peak in Human. The findings were published in PLOS Biology. The research also noted that Homo floresiensis, with its smaller brain and mixed locomotion, showed a weaker predicted hand preference, supporting the theory. While the study provides a significant clue, it still leaves open questions about the persistence of left-handedness and the role of culture.