A study conducted by researchers at the University of Chieti-Pescara in Italy has confirmed a hypothesis that shows that while right-handed people have an advantage in cooperative behavior, left-handed people – particularly men, have an advantage in competitive behavior, especially in one-on-one situations. This hypothesis is based on evolutionarily stable strategy (ESS), a concept from game theory applied to evolution.
Thus the ESS explains why the proportion of left-handed people remains low but stable. If almost everyone in a population is right-handed, being left-handed provides a frequency-dependent advantage: being in the minority, left-handers may be less predictable in competitive interactions (for example, a boxing match), which may translate into smaller advantages (left hooks!). But if left-handed use became very common, that advantage would disappear as other people would adapt to encountering left-handed people with the same frequency. In evolutionary terms, a “stable equilibrium” is reached when the majority are right-handed and the minority are left-handed, because neither “strategy” can completely eliminate the other because their advantages depend on how often each occurs in the population.
How can any study support this hypothesis? Italian researchers conducted two experiments to see whether dominant handedness was linked to a specific personality type. The results were recently published in the academic journal Scientific Reports.
right wing vs left wing
In the first experiment, about 1,100 participants completed questionnaires designed to measure their spontaneity (their level of dexterity between one hand and the other) and various aspects of competitiveness, such as their inclination to achieve personal goals or their dislike of anxiety-induced competition. The results showed that people who identified more left-handedness showed higher levels of personal development-oriented competition and lower levels of avoidance anxiety. That is, left-handed people are more willing to engage in competitive situations than right-handed people.
Furthermore, when strongly lateralized groups were compared (just pure righties, no ambidextrousness), left-handers scored higher on “hypercompetitiveness”, a trait reflecting a strong desire to win, even at the expense of others.
In the second experiment, a subgroup of 48 participants (half right-handed and half left-handed, with an equal proportion of men and women) took a pegboard test, a classic laboratory test that measures manual dexterity. Interestingly, there were no significant differences observed between left-handers and right-handers or between laterality measures and competitiveness scores. This suggests that hand preference and competitiveness are not directly related to motor skills.
give them a hand
According to the study’s authors, left-handedness is not simply a biological accident, but a trait that may provide an advantage in competitive contexts and is therefore worth preserving. This, at least partially, supports the idea that the unequal distribution between right-handed and left-handed people may be maintained by evolutionary balance. While the right-handed majority favors social cooperation, the left-handed minority benefits in competitive contexts, where surprise plays a role.
But what about other personality types? Are left-handed people more extroverted or more emotionally unstable? The study cited here found no significant differences between left-handed and right-handed people in the Big Five personality traits (openness, conscientiousness, extraversion, agreeableness, and neuroticism). Nor was there any association between apathy and levels of depression or anxiety in this sample of people without psychiatric diagnoses. This suggests that the advantage associated with left-handedness is more linked to competitiveness than general differences in personality or mental health.
The study also examined differences based on gender. In general, men scored higher in hyper-competitiveness and growth-oriented competitiveness, while women showed a greater tendency to avoid competition due to anxiety. This suggests that the interaction between hand preference, competitive profile, and gender is complex and likely influenced by multiple biological and environmental factors that require further investigation.
This story originally appeared on WIRED en Español and is translated from Spanish.
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