The study suggests that handedness is not innate, but instead develops as an acquired habit formed in early childhood through repeated use.
Researchers from the Chinese Academy of Sciences (CAS) have proposed the “Hypothesis of Acquired Conservation of Right-Hand Preference.” The study suggests that handedness is not innate, but instead develops as an acquired habit formed rapidly during early childhood through repeated use.
To test this idea, scientists used untrained mice—which typically use both paws equally—and placed them in challenging feeding situations that required them to choose one paw to access food. After just 5 to 7 forced trials, the mice developed a lasting preference that persisted for more than a month, even after they were no longer required to use a specific limb.
The most notable finding emerged when researchers attempted to reverse the mice’s established habits:
Right-paw habits proved highly persistent and difficult to change, while left-paw habits were more easily corrected or shifted back to the right paw. When researchers forced the animals to alternate paws, most eventually reverted to using the right paw, with only a small minority remaining left-pawed—closely mirroring the roughly 90/10 distribution observed in humans.
Published in the Journal of Genetics and Genomics, the study concludes that human handedness may result from “acquired conservation.” It suggests that while individuals may begin with equal potential, early repetition combined with a natural bias toward right-sided preference helps solidify handedness over time. Some research also notes a slightly higher rate of left-handedness in Western Europe and North America, though scientists continue to debate whether this is influenced by genetics or cultural pressures that historically discouraged left-hand use in childhood.
“A right-hand preference, once formed, is more stable and easier to sustain than a left-hand one, giving it a cumulative advantage in individual development. Reinforced by a right-hand-dominant social environment, this tendency ultimately creates our ‘right-handed world,’” said Sun Zhongsheng, a researcher at the Institute of Zoology at CAS.
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