About 90% of the world’s population is right-handed. For decades, researchers have been racking their brains to find the reason for this unique predominance among primates: they may finally have found the answer.
According to a recent study carried out by researchers at the University of Oxford, published in the journal PLOS Biology and relayed by Science Daily, this human predilection for the right hand is due to two major evolutionary changes in the species: bipedal walking and the development of a brain larger than that of our ancestors.
Walk without hands
The team of researchers, led by Rachel M. Hurwitz, Thomas A. Püschel and Chris Venditti, studied 2,025 monkeys and great apes representing 41 different primate species to carry out modeling taking into account the evolutionary relationships between the species.
By analyzing tool use, diet, habitat, body size, social structure, brain size and locomotor patterns, scientists sought to determine where the origin of what is known as manual laterality, or hand preference, between left-handed and right-handed people might come from.
According to their research, early hominids, such as Ardipithecus and Australopithecus, probably had a slight preference for the right hand, similar to that observed today in great apes, but this tendency was especially accentuated with the emergence of the genus Homo. It would be with Homo ergaster, Homo erectus and the Neanderthal that the preference for the right hand would have asserted itself, to the point of becoming a real dominance in modern humans.
For experts, the evolutionary process probably took place in two stages. First, bipedal walking, freeing the hands from locomotor use, would have created new pressures favoring a more specialized and asymmetrical use of the hands. Subsequently, as the human brain became larger, the complexity of motor control and lateralization increased and, with it, the use of the right hand.
