Researchers at the University of California, Los Angeles (UCLA) have found that the superior performance of the dominant hand during complex movements is driven not by innate brain organization, but by years of practice. The findings suggest that accumulated motor experience, rather than inborn neural advantages, plays the key role in hand dominance. The study was published in the Proceedings of the National Academy of Sciences (PNAS).

Handedness is considered one of the fundamental characteristics of humans and many other animal species. For decades, the prevailing theory has been that the brain's dominant hemisphere is inherently better equipped to control complex movements. Primates, cats, kangaroos, and even mice also show preferences for one hand or paw, although this tendency is generally less pronounced than in humans.

To test this hypothesis, the researchers asked healthy volunteers to complete a series of motor tasks while their movements were recorded using a video-tracking system. Participants first reached for a target and grasped an object, then performed a more challenging task in which they used a long stick to retrieve an object placed beyond their reach.

The results showed that both hands performed equally well during the simple tasks. Differences emerged only during tool use: the dominant hand adapted more quickly to the new conditions and learned the unfamiliar movement more efficiently.

According to the authors, these findings indicate that the dominant hand's advantage develops through years of repeated use rather than reflecting an innate superiority. The study provides new insights into the mechanisms of motor learning and neuroplasticity and may contribute to the development of improved rehabilitation strategies for patients recovering from injuries or stroke.