A great deal of recent research on evolution focuses on altruism—the tendency of creatures to help others, often at great cost to themselves. This is especially true of human beings, who help one another for a variety of good evolutionary reasons. For instance, people help kin, which is a way of preserving the genes that they share. People help others who are likely to help them back. But the prevalence of altruism also raises an evolutionary paradox: If evolution has selected humans to be nice and kind, how do we explain the high prevalence of jerks?
Research suggests that one fundamental reason people are altruistic is to make themselves attractive to sexual partners. In a large-scale cross-cultural study of qualities found attractive in mates, published in the Journal of Cross-Cultural Psychology in 1990, David Buss and colleagues asked young adults across the globe to rate how important various attributes were in long-term mates. Across a broad range of cultures, they found that kindness placed toward the top of the list. Mate preferences are a very strong evolutionary force, so if people prefer kindness in mates, kindness will become a common attribute in the species. This is one reason why there are so many good people.
So how can it be adaptive from an evolutionary point of view to engage in behavior that other people find objectionable and even hateful? Recent work by researchers including David Schmitt of Brunel University London and Peter Jonason of Western Sydney University has focused on a group of personality traits known as the “dark triad,” which are negatively associated with character and ethics. In a much-cited 2002 paper in the Journal of Research in Personality, Delroy Paulhus and Kevin Williams, both then at the University of British Columbia, defined the dark triad as consisting of narcissism (an excessive focus on oneself), Machiavellianism (manipulating others for one’s own gain), and psychopathy (an overall disregard for others).
People who score high on the dark triad typically engage in behaviors that most people would find obnoxious or immoral. In a 2017 paper in the journal Psychological Topics, Prof. Schmitt and colleagues used data from a global survey of more than 30,000 participants to establish that people who score high on a test for narcissism are also more likely to have short-term sexual relationships, to engage in intimate partner violence and to be more likely to steal other people’s romantic partners. Studies by my own research team have found that people with high scores on the traits that define the dark triad are also particularly likely to cut friends and relatives out of their lives and to plot revenge against others for even minor transgressions.
In the same study, we found that slightly more than 10% of the population may have substantial dark-triad tendencies. What’s more, scores on each of the dimensions of the dark triad were positively correlated with one another: People with a tendency toward narcissism are also more likely to demonstrate Machiavellianism and psychopathy, and vice versa.
This finding raises an evolutionary question: If humans generally find these traits repulsive and prefer not to mate with those who possess them, how did the dark triad manage to become so prevalent? What is the evolutionary benefit of being a bad person?
A 2013 paper found that people who experienced low quality or irregular parental care were more likely to develop dark triad traits.
To understand how some people flourish in life by being nice while others succeed by being jerks, evolutionary psychology turns to the concept of “strategic pluralism.” This is the idea that members of the same species might evolve different and even contradictory strategies for survival, depending on the conditions they face. If an individual grows up in unstable, harsh and unsafe conditions, it makes sense to reproduce early and often, since he or she might not have much time left. On the other hand, if an individual is raised in stable and safe conditions, they will have more time to wait, choose the perfect mate and have only a few children who are given enormous amounts of time and attention. In this way, the same species might develop both “fast” and “slow” life strategies.
We see evidence of strategic pluralism in the natural world all the time. For instance, behavioral scientists who study wood frogs have found that the males employ two distinct strategies in trying to attract a mate. One is to carve out a large territory and issue regular mating calls. Once a female wood frog approaches, the male tries to mount her, while she tries to shake him off. This is a way of selecting for larger mates, since if the male is large enough, it is harder for her to dislodge him.
This preference leaves smaller male wood frogs in a pickle because they can’t stay mounted on the female. So these males have evolved an alternative strategy: They hang out near a large, dominant male as he calls out for females. When a female comes by and releases her eggs—in wood frogs, fertilization takes place outside the body—the satellite male will try to quickly enter the picture and fertilize them with his sperm.
In the wood-frog mating system, then, we see two very different behavioral strategies, each of which can achieve reproductive success. Smaller male frogs face obstacles to mating, forcing them to use an aggressive or “fast” mating strategy, while larger frogs have the luxury of using a safer, “slower” mating strategy.
Something similar may be responsible for the evolution of antisocial personality traits in human beings. In a 2013 paper in the journal Personality and Individual Differences, entitled “The Making of Darth Vader: Parent-Child Care and the Dark Triad,” Dr. Jonason and colleagues found that people who experienced low-quality or irregular parental care were more likely to develop dark-triad traits. They proposed that “stressful, harsh, or unstable child-parent relationships might activate an approach to life, captured by the dark triad, orienting individuals towards seeking immediate returns in mating.” Such challenging circumstances don’t reward “slow” life strategies like patience and cooperation; rather, they would encourage the development of “fast” strategies dependent on aggression and deceit.
And for such strategies, qualities like narcissism and Machiavellianism may be highly adaptive, helping individuals to outwit rivals and achieve success, including reproductive success. Research has consistently found that those who score high on the dark triad tend to be “short-term mating strategists.” In other words, they are more likely to pursue brief sexual encounters, and they have less of a problem than most people with behavior like breaking up other couples, keeping a backup partner in the wings and engaging in infidelity.
Unpacking the elements of the dark triad can give us insights into how these traits are biased toward short-term mating. For instance, someone who is manipulative may not win many points for kindness, which works best in long-term mating contexts, but they may well be effective at manipulating potential mates into brief sexual encounters. This suggests that, as long as human beings are subject to challenging environments during their development—whether social or physical—the dark triad will confer an advantage on some individuals. In other words, unfortunately, jerks may always be with us.
—Dr. Geher is a professor of psychology and the founding director of the Evolutionary Studies Program at the State University of New York at New Paltz.