Why Do Most People Use the Right Hand? Latest Scientific Explanation
Approximately 90% of humans worldwide use their right hand, a widespread dominance not seen in any other primate species. The mystery behind this unique phenomenon has been unravelled through a recent study published in the journal PLOS Biology.
Researchers analysed data from 2,025 individuals across 41 monkey and ape species. Considering evolutionary relationships, they tested various popular theories on the origins of hand preference (left or right) in different species.
Factors such as diet, habitat, social behaviour, tool use, and body size were initially assessed together. In initial analysis, the human tendency towards right-handedness appeared highly anomalous and unique compared to other primates.
The researchers then introduced two new variables into their model: brain volume size and arm-to-leg length ratio (an indicator of bipedal capability). The results indicated that right-handed dominance is a product of human physical transformation.
Based on these findings, the evolution of right-handedness occurred in two main stages:
Researchers also traced the timeline of right-handedness in extinct human ancestors. Results showed that early ancestors like Ardipithecus ramidus and Australopithecus afarensis likely had only a very weak right-hand preference, similar to modern great apes.
A significant shift became evident with the emergence of the Homo genus. Species such as Homo ergaster, Homo erectus, and Neanderthals showed increasingly intense right-handed tendencies, peaking in modern Homo sapiens.
Interestingly, Homo floresiensis, or the dwarf human from Indonesia, is predicted to have had a much weaker right-hand preference. This aligns with their anatomy, featuring a small brain volume and a body structure not fully specialised for bipedalism.
Although biological factors form the foundation, cultural elements have also refined this dominance. Since prehistoric times, tools and writing systems have predominantly been designed for right-handed users, ensuring the tradition has been passed down through generations. (H-3)