Upright posture links to right-handedness

Why this is here: The team predicted a handedness direction of 0.0 for humans, but after including brain size and bipedalism factors, that prediction rose to 0.74—nearly matching the observed value.

Researchers at the University of Oxford analyzed 41 primate species, finding a connection between handedness, brain size, and walking upright. The team, led by Dr.

Thomas A. Püschel and Rachel M.

Hurwitz, used a comparative meta-analysis to examine over 2,025 individuals. They discovered humans uniquely favored the right hand with an index of 0.76, unlike other primates.

This strong bias lessened when researchers accounted for brain size and the ratio of arm to leg length—a measure of bipedalism. Humans have a notably low arm-to-leg ratio of 72, indicating well-developed walking ability. Early hominins like Ardipithecus ramidus showed only mild right-hand preference, while later species like Homo neanderthalensis leaned more strongly right.

The study acknowledges challenges in comparing data across species and the potential role of culture in reinforcing handedness. Further research may reveal parallels in other animals, offering a broader understanding of lateralization and manual specialization.