A new study in PLOS Biology resolves why humans are predominantly right-handed while other primates are not. Researchers found that once models account for upright walking and larger brain size, humans align with primate patterns. This eliminates the previous view of human handedness as an evolutionary anomaly, reframing it as a consequence of our unique locomotor and neurological adaptations.

Analysis of extinct hominins reveals a clear gradient. Early species like Ardipithecus and Australopithecus showed only mild rightward hand preferences, similar to modern great apes. The bias strengthened significantly through the Homo lineage—from Homo ergaster and Homo erectus to Neanderthals—culminating in the extreme pattern seen in Homo sapiens.

The findings support a two-stage evolutionary process. Bipedalism freed the hands for complex tasks first, creating selective pressure for lateralized manual behaviors. Subsequently, brain expansion and reorganization amplified the right-hand bias. The sole exception, Homo floresiensis, fits the model due to its small brain and retained climbing adaptations, underscoring the roles of both posture and cognition.

This research provides a unified explanation for a long-standing puzzle in human evolution. It demonstrates that our hand preference is not an isolated trait but emerged from fundamental shifts in how our ancestors moved and thought, linking behavior directly to anatomical change.