About 90 percent of people are right-handed. According to scientists from the University of Oxford the predominance of the right hand could have arisen already at the moment when our ancient ancestors started to walk on two feet and freed their hands for other activities. The enormous development of the terminal brain led to the differentiation of its functions. And rightly so in the left hemisphere, which controls the right side of the body, the main center for manual dexterity arose.
The authors of the research published in the journal PLOS Biology analyzed data on 2,025 individuals from 41 species of monkeys and apes. Scientists have compared different theories explaining the emergence of one-handed preference, such as tool use, brain size, locomotion or social organization. “Our results suggest that it probably has to do with some of the key traits that make us human, especially with upright walking and the development of a larger brain,” said study author Thomas Püschel from the University of Oxford.
According to the authors, the combination of a larger brain and anatomical features associated with walking in pairs was an important factor. Thanks to this, they were able to estimate the probable hand preference even in extinct human ancestors. The study suggests that Ardipithecus and Australopithecus species may have had a slight right-handed preference similar to today’s great apes. However, a more pronounced dominance of the right hand appeared only in the genus Homo, i.e., for example, in Homo erectus or Neanderthals. It is most prominent today in Homo sapiens.
The exception is Homo floresiensis, nicknamed the “hobbit” from Indonesia. This species had a smaller brain and, according to the study, a weaker one-handed preference. Scientists now believe that walking upright came first, freeing the hands from movement. “With hands free for other activities, evolution began to favor ancestors who used them for manual activity,” the study says.
