New Research Links Human Right-Handedness to Bipedalism and Brain Size

A study published in PLOS Biology suggests human right-handedness evolved from bipedalism and brain enlargement. Researchers analyzed handedness across 41 primate species using evolutionary and statistical methods. Two key drivers emerged: brain size and relative arm-to-leg length (a proxy for upright walking). They posit that walking on two legs freed hands for tasks, favoring fine motor skill specialization, then brain reorganization cemented right-hand bias. Early hominins like Ardipithecus ramidus and Australopithecus afarensis showed mild right-handedness, strengthening in Homo erectus and Homo neanderthalensis, peaking in Homo sapiens. Homo floresiensis was an exception due to small brain and mixed locomotion. About 10% of humans are left-handed, linked to brain asymmetry and genetics (rare gene variants found in 2024). Researchers also note similar limb preferences in parrots, kangaroos, and wallabies, suggesting bipedalism triggers handedness evolution.