Researchers from the Chinese Academy of Sciences (CAS) have proposed the “Hypothesis of the Acquired Preservation of Right Hand Preference.” The study suggests that dexterity is not something we are born with, but rather a habit that develops rapidly during early childhood through repeated use.
To test this, scientists used untrained mice – which normally use both paws equally – and placed them in challenging feeding scenarios where they had to choose a specific paw to reach food. After just five to seven attempts at forced use, mice developed a lasting preference that lasted for more than a month, even when they were no longer forced to use a specific limb. The most striking discovery occurred when researchers tried to change the mice’s habits:
Right paw habits were persistent and extremely difficult to change. On the other hand, the habits of the left paw could easily be corrected or shifted back to the right paw. When forced to alternate their paws, the vast majority of mice ended up sitting on the right paw. Only a small, stubborn minority remained left-handed, accurately mirroring the 90/10 split found in humans.
The study published in the Journal of Genetics and Genomicsconcludes that human dexterity is the result of acquired conservation. This further suggests that while we may start with the same potential, repetition in early life and an underlying biological persistence for the right side reinforce the preference. Some studies indicate a slightly higher prevalence of left-handedness in Western Europe and North America. Scientists often debate whether this is due to genetic or cultural pressure to correct left-handedness in childhood.
“A right-hand preference, once formed, is more stable and easier to maintain than a left-hand preference, thus providing a cumulative advantage in individual development. Reinforced by a right-handed dominant social environment, this tendency ultimately creates our ‘right-handed world,'” says Sun Zhongsheng, a researcher from the Institute of Zoology of the CAS.
