Scientists finally uncover why most of us favour our right hand

About 90% of humans across cultures prefer their right hand for tasks. Research on handedness across species shows no other primate species has a population-level preference of similar magnitude. Handedness appears to result from coordinated influences of genes, brain development, and bodily development during the womb. A new study proposes that right-handedness emerged around the time early ancestors began walking upright and brains became larger. Data from 2,025 individuals across 41 monkey and ape species were used to test hypotheses involving tool use, diet, habitat, body mass, social organization, brain size, and movement. The best explanation involved larger brains and the relative length of arms versus legs. Estimates for extinct ancestors suggest mild rightward preferences in Ardipithecus and Australopithecus, with stronger right-handedness developing in Homo, including Homo ergaster, Homo erectus, and Neanderthals.

"Our results suggest it is probably tied to some of the key features that make us human, especially walking upright and the evolution of larger brains. Scientists assessed data on 2,025 individuals across 41 species of monkeys and apes for the study. Among these species, researchers tested which major existing hypotheses best explained how handedness evolved, including tool use, diet, habitat, body mass, social organisation, brain size and movement."

"Scientists found the best theory explaining handedness when they factored in a large brain and the relative length of arms versus legs, a standard anatomical marker of two-legged movement. Using these two traits, researchers could also estimate likely handedness in extinct human ancestors. They found that early human ancestors like Ardipithecus and Australopithecus also may have had mild rightward preferences, similar to modern great apes."

"But exactly why humans ended up so overwhelmingly right-handed remains an enigma, until now. A person's genes, their brain and the body's development process from the womb all seem to work together to contribute to handedness. Decades of research into handedness across species has revealed that no other primate species showed a population-level preference on this scale."

"But right-handedness seems to become more prominent in the genus Homo, including in Homo ergaster, Homo erectus and Neanderthals. A rightward bias became hardened into the near-universal pattern seen today. The study suggests the trait emerged around the time early human ancestors began walking upright and their brains started becoming bigger."

Read at Irish Independent