A new study published in Evolutionary Behavioral Sciences sought to replicate the finding that there is a positive association between altruism and mating success. However, it revealed no relation between altruism and various indices of mating success.
Altruism is a cross-cultural phenomenon that poses an evolutionary puzzle. Why would someone carry out a behavior that benefits another while incurring a personal cost? Such costly behaviors should not be favored by natural selection.
One theory is that altruism signals desirable qualities, such as cooperativeness or genetic endowment, thereby attracting mates. Indeed, some findings have shown that altruistic individuals are perceived as more desirable partners.
A 2017 study conducted by Arnocky and colleagues reported that altruistic behavior was positively associated with self-reported mating success, number of sexual partners (both lifetime and casual), and frequency of copulation with current partner. These findings were stronger for women, than men, and held when controlling for age and personality. The researchers concluded that altruism serves as a costly signal that can provide a reproductive benefit.
In this work, Lili J. Judd and colleagues conducted a direct replication of Arnocky et al.’s (2017) Study 1, arguing that, “If an evolutionary explanation of the observed effects is correct, then similar findings should emerge in diverse samples and other world regions.”
The researchers recruited 445 unmarried Australian participants, of which 220 were currently in a romantic relationship while 225 were not. Participants provided demographic information (e.g., age, sex, ethnicity), completed measures of altruism, personality (capturing the Big Five domains), and self-perceived mating success. Single items measures assessed for number of lifetime sex partners, number of lifetime casual sex partners, and for those in a romantic relationship, how many times they had engaged in sex with their partner in the past 30 days.
Judd and colleagues found that self-reported altruism was not associated with self-reported mating success across the numerous indices. This was also the case when controlling for age and personality traits. Further, participants’ sex had no moderating effects, with men and women showing the same pattern of results. The authors write, “In short, findings conflict with those reported in the original study and provide evidence that altruism does not predict mating success in humans.”
A potential explanation for the inconsistent pattern of results between the present research and Arnocky et al.’s (2017) study is the different population groups (i.e., Australian vs. Canadian). It could be the case that altruism is more valued in some regions compared to others. However, cultural differences would be evidence against an evolutionary explanation.
A second explanation could be random error, whereby the costly signaling hypothesis is correct, but was not observed in the current work due to the sample size.
The authors conclude, “We recommend further research that tests for cross-cultural variation to help establish altruism’s cultural and evolutionary contributions to mating success across world regions.”
The study, “Altruism Does Not Predict Mating Success in Humans: A Direct Replication”, was authored by Lili J. Judd, Jessica G. Mills, and Mark S. Allen.