Science says that left-handed people are more competitive

Existence itself Left-handedness seems to challenge Darwin. According to the theory of evolution by natural selection (in very simplified terms), a species should retain characteristics that are necessary for survival and reproduction and eliminate those that are not so useful. However, about 10% of people go on to develop greater dexterity in their left hand, a rate that has remained constant throughout history. Why do humans continue to retain this strange ability?

A study conducted by researchers at the University of Chieti-Pescara in Italy aims to confirm a hypothesis suggesting that while right-handed people have advantages in cooperative behaviors, left-handed people – especially males, the study notes – have advantages in competitive behaviours, especially in one-on-one situations. This hypothesis is based on evolutionarily stable strategy (ESS), a concept from game theory applied to evolution.

This is how ESS explains why the proportion of left-handed people remains low but constant. If almost everyone in a society is right-handed, then being left-handed provides a frequency-based advantage: being in the minority, left-handers are less predictable in competitive interactions (e.g., a boxing match), which may translate into small advantages (left hook!). But if left-handedness becomes too common, this advantage will disappear because others will 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 change depending on how frequently each occurs in the population.

How can the study support this hypothesis? Italian researchers conducted two experiments to see if a dominant hand was linked to any 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 handedness (level of dexterity between one hand and the other) and various aspects of competitiveness, such as their tendency to pursue personal goals or their aversion to anxiety-driven competition. The results showed that people who identified with greater left-sidedness tended to show higher levels of personal development-oriented competitiveness and lower levels of anxious avoidance. This means that left-handers tend to engage in competitive situations more than right-handers.

Additionally, when groups with strong lateral orientations (just pure south feet, no use of both hands) were compared, left-handers scored higher on “hypercompetitiveness,” a trait that connotes an intense desire to win, even at the expense of others.

In the second experiment, a subgroup of 48 participants (half right-handed, half left-handed, equal proportions of men and women) took the Pegboard test, a classic laboratory test that measures manual dexterity. Interestingly, no significant differences were observed here either between left- and right-handers or between lateralization measures and competitiveness scores. This suggests that hand preference and competitiveness are not directly related to motor skills.

Give them a helping hand

According to the study’s authors, left-handedness is not just a biological accident, but rather a characteristic that may offer advantages in competitive contexts and is therefore worth preserving. This supports, at least in part, the idea that the unequal distribution between right- and left-handers may be maintained through evolutionary balance. While the right-handed majority prefers 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 emotionally unstable? The study reported here found no significant differences between left- and right-handed people in the Big Five personality traits (openness, conscientiousness, extraversion, agreeableness, and neuroticism). There was no relationship between handedness and levels of depression or anxiety in this sample of people without a psychiatric diagnosis. This suggests that the left-handed advantage is more related to competitive ability than to general differences in personality or mental health.

The study also examined differences by gender. Men generally scored higher on hypercompetitiveness and development-oriented competitiveness, while women showed a greater tendency to avoid competition due to anxiety. This suggests that the interplay between hand preference, competitive profile, and sex is complex and likely influenced by multiple biological and environmental factors that require further investigation.

This story originally appeared on WIRED en Español and was translated from Spanish.