Handedness is not an innate biological blueprint but a skill refined by a lifetime of tool use, according to research published Tuesday in the journal PNAS. A study led by John Krakauer, an external researcher at the Santa Fe Institute (SFI) from Johns Hopkins University, in collaboration with Ahmet Arac and Nicolas Y. H. Jeong Lee of the University of California, Los Angeles, found that dominance in dexterity emerges from practice rather than being pre-programmed in the brain.
Why dexterity differs from hand preference
Researchers distinguish between “preference” and “dominance,” two concepts often grouped under the term “manual laterality.” According to the study, hand preference—the instinct to reach for an object with a specific hand—likely has biological roots present before birth. However, dominance—the actual gap in skill between the two hands—is a byproduct of experience.
The team used 3D motion capture to track participants during various tasks. While simple reaching movements showed no significant performance difference between hands, the gap widened significantly when participants used tools. The non-dominant hand struggled specifically with the complex, curved paths required to manipulate external objects, suggesting that dominance is a learned adaptation to tool usage.
When participants in the study were tasked with writing using their elbows, the traditional “dominance” of one hand disappeared. With equal practice, both elbows improved at the same rate, eventually outperforming the non-dominant hand’s baseline.
Is manual laterality a cultural byproduct?
The findings suggest that human dexterity is a feedback loop. “We don’t prefer the dominant hand because it is more skillful,” John Krakauer stated in a release from the SFI. “It becomes more skillful because we prefer it.”
This perspective shifts the understanding of human motor control. Ahmet Arac suggests that manual laterality acts as a “fingerprint of human tool-use culture.” Because humans are tool users and creators, the asymmetry in our hands may be an emergent property of our interaction with the environment rather than a fixed genetic trait. This implies that the brain’s motor control centers adapt to the cultural demands of the tools we invent.
What happens next in laterality research?
The research team plans to investigate scenarios where preference and practice diverge to further test these findings. Future studies may look at:
- Forced adaptation: Examining left-handed individuals who are required to use tools designed for the right hand.
- Clinical rehabilitation: Analyzing stroke survivors who experience shifts in manual preference.
- Amputee motor control: Observing how individuals develop dexterity using unconventional movement patterns after limb loss.
If you want to improve dexterity in your non-dominant hand, focus on practicing complex, curved movements rather than simple reaching tasks. The study indicates that the brain builds asymmetry through the specific, demanding requirements of tool manipulation.
Frequently Asked Questions
Is being left-handed or right-handed genetic?
According to the study, while the preference for a hand may have biological or prenatal roots, the dominance (the superior skill of one hand over the other) is largely a result of lifelong practice with tools.
Can you change your dominant hand?
The study suggests that dominance is built through practice. When participants trained their non-dominant side, they showed significant improvement, indicating that manual skill is plastic and responsive to training.
Does the brain have a specialized motor center for the dominant hand?
The research challenges the traditional view that dexterity is hard-wired into a specific cerebral hemisphere from birth. Instead, it argues that skill asymmetry accumulates over time through the interaction between biology, behavior, and culture.
Have you ever tried to train your non-dominant hand to perform complex tasks? Share your experiences in the comments below or subscribe to our newsletter for more updates on the latest behavioral science research.
