Two Evolutionary Shifts Pushed Humans Toward a Right-Hand Bias

An Oxford study across 41 primate species finds that humans aren’t evolutionarily exceptional in handedness once brain size and limb proportions are included; a two-stage path links upright walking (freed hands) and later brain expansion to the strong right-hand bias (mean handedness index 0.76), suggesting the 90% right-handed world arose from changes in movement and brain growth rather than a single gene, with culture possibly reinforcing it.