Scientists have long pondered why about 90% of humans are right-handed while other primates show no clear preference for one hand. A recent study from the University of Oxford suggests this might link back to two significant milestones in human evolution: walking on two legs and developing larger brains.
Most species of primates, including monkeys and apes, use both hands almost equally. However, humans are unique in their strong right-handedness. Researchers explored various explanations—like genetics, brain structure, and tool use—but the roots of this handedness remained unclear.
The Oxford team analyzed data from 2,025 people across 41 primate species. They specifically looked at factors such as brain size and arm-to-leg ratio, which indicates a creature’s ability to walk upright. This fresh approach revealed that once these factors were considered, humans appeared less like outliers in the evolutionary tree. Instead, larger brains and bipedalism might have led to our strong preference for the right hand.
The study, detailed in PLOS Biology, underscores an evolutionary shift. Early human relatives, like Ardipithecus, showed only mild right-hand preferences akin to modern great apes. This changed with the genus Homo, where species like Neanderthals exhibited a stronger tendency towards right-handedness.
Interestingly, researchers also identified an exception: Homo floresiensis, or the “hobbit” species, likely had less preference for one hand due to their smaller brain and adaptations for both climbing and walking.
According to Dr. Thomas A. Püschel, who led the study, this research is the first of its kind to examine several theories of human handedness together. He noted that understanding these trends could shed light on which traits are ancient and shared among species, and which are uniquely human.
The persistence of left-handedness still puzzles scientists. Despite the overwhelming right-handedness in modern populations, left-handed individuals remain. Exploring how culture and other species exhibit similar trends could provide new insights into handedness.
For more in-depth information, refer to the study titled “Bipedalism and brain expansion explain human handedness” published in PLOS Biology here.
Understanding why we favor one hand can reveal broader aspects of human evolution and offer clues about our ancestral past.
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Anthropology,Evolution,Homo Sapiens,University of Oxford
