Scientists finally decode why most humans are right-handed

Key Points:

• Approximately 90% of humans worldwide prefer using their right hand, a dominance that may have originated when early human ancestors began walking upright and their brains started enlarging, according to a new study published in PLOS Biology.
• Researchers analyzed data from 2,025 individuals across 41 monkey and ape species, testing hypotheses related to tool use, diet, habitat, body mass, social organization, brain size, and locomotion to understand the evolution of handedness.
• The study found that a combination of larger brain size and anatomical markers of bipedalism (such as arm-to-leg length ratio) best explained the emergence of right-handedness, with early hominins showing mild rightward preferences and the trait becoming more pronounced in the genus Homo.
• Species like Homo ergaster, Homo erectus, and Neanderthals exhibited stronger right-hand dominance, while Homo floresiensis, with a smaller brain and mixed locomotion, showed weaker hand preference, supporting the link between brain size, upright walking, and handedness.
• Scientists propose that upright walking freed the hands for manual tasks, which were favored by evolution, and subsequent brain growth solidified right-handedness as a near-universal human trait; future research aims to explore cultural influences and the persistence of left-handedness.