Left-Handed People Are More Competitive, Says Science
The very existence of left-handedness seems to defy Darwin. According to the theory of evolution by natural selection (in very simplified terms), a species should retain the characteristics necessary for its survival and reproduction and discard those which are not very useful to it. And yet, about 10% of people continue to develop greater dexterity in their left hand, a rate that has remained stable throughout history. Why do humans continue to retain this special ability?
A study by researchers at the University of Chieti-Pescara in Italy attempted to confirm a hypothesis that while right-handers have advantages in cooperative behaviors, left-handers — particularly men, the study notes — have advantages in competitive behaviors, particularly in one-on-one situations. This hypothesis is based on the evolutionarily stable strategy (ESS), a concept from game theory applied to evolution.
This is how the ESS explains why the proportion of left-handers remains low but constant. If almost everyone in a population is right-handed, being left-handed provides a frequency-dependent advantage: being a minority, left-handers are less predictable in competitive interactions (e.g., a boxing match), which can translate into small advantages (left hook!). But if left-handers became very common, this advantage would disappear as others would adapt to encountering left-handers with the same frequency. In evolutionary terms, a “stable equilibrium” is achieved when the majority is right-handed and a minority is left-handed, because neither “strategy” can completely eliminate the other since their advantages change depending on the frequency of each in the population.
How can a study support this hypothesis? Italian researchers conducted two experiments to see if a dominant hand is linked to a specific personality type. The results were recently published in the academic journal Scientific Reports.
Right-handed versus left-handed
In the first experiment, about 1,100 participants completed questionnaires designed to measure their dexterity (their level of dexterity between one hand and the other) and various facets of their competitiveness, such as their propensity to achieve personal goals or their aversion to anxiety-driven competition. Results showed that people who identified with greater left-handedness tended to exhibit higher levels of self-development-oriented competitiveness and lower levels of anxious avoidance. That is, left-handers tend to be more inclined to engage in competitive situations than right-handers.
Additionally, when comparing highly lateralized groups (just pure lefties, no ambidextrous), lefties performed better in terms of “hypercompetitiveness,” a trait that involves an intense 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 equal proportions of men and women) took a pegboard test, a classic laboratory test that measures manual dexterity. Interestingly, no significant differences were observed here, neither between left-handers and right-handers, nor between handedness 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 authors, left-handedness is not simply a biological accident, but a characteristic that can provide advantages in competitive settings and is therefore worth preserving. This supports, at least in part, the idea that the unequal distribution between right-handers and left-handers could be maintained by an evolutionary balance. While the right-wing majority favors social cooperation, the left-wing minority benefits from it 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-handers and right-handers in the Big Five personality traits (openness, conscientiousness, extraversion, agreeableness, and neuroticism). There was also no relationship between labor force and levels of depression or anxiety in this sample of people without a psychiatric diagnosis. This suggests that the advantage associated with being left-handed has more to do with competitiveness than general differences in personality or mental health.
The study also looked at gender differences. Men, in general, scored higher on hypercompetitiveness and developmental competitiveness, while women showed a greater tendency to avoid competition due to anxiety. This suggests that the interaction between hand preference, competitive profile, and sex is complex and likely influenced by multiple biological and environmental factors that warrant further investigation.
This story was originally published on WIRED en Español and was translated from Spanish.
