Gossiping and manipulation linked to higher fertility in new psychology study

Spreading rumors and intentionally excluding peers from social groups are behaviors often viewed as undesirable. A new study suggests that this type of covert hostility is linked to a higher likelihood of being in a romantic relationship and having more children. The research, published in Evolutionary Psychological Science, indicates that subtle forms of aggression might provide a reproductive advantage in modern populations.

Evolutionary psychologists track the number of children people have to measure evolutionary fitness. This metric reflects how successfully an individual passes down their genetic material to the next generation. If a specific heritable trait results in more offspring, its underlying genetics will become more common in the population over time. This process is the basic mechanism of natural selection.

Researchers study various psychological traits to see if they are actively being shaped by natural selection in the modern era. Characteristics like extroversion and neuroticism have already shown links to reproductive outcomes. Evolutionary theorists propose that aggressive behavior might also be an adaptive trait. Aggression can help individuals defend territory, secure limited resources, and compete for mating opportunities.

Human aggression is broadly divided into two categories based on how it is expressed. Direct aggression involves overt physical or verbal attacks, such as punching or yelling. Indirect aggression relies on covert tactics to inflict harm. A specific type of indirect aggression, known as relational aggression, focuses on damaging a victim’s social standing and interpersonal connections.

Relational aggression includes gossiping, withholding friendship, or manipulating others to isolate a rival. From an evolutionary perspective, direct physical aggression carries high risks. An overtly aggressive person could suffer physical injury, face social exile, or incur legal punishments. Relational aggression maximizes harm to the victim while keeping the aggressor relatively safe from physical retaliation or immediate blame.

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Past research has struggled to directly link aggression to actual reproductive success in modern humans. Evolutionary studies often relied on proxies for reproduction, like the number of dating partners or a person’s age during their first sexual experience. When data on actual fertility was available, researchers frequently used biological proxies for aggression, such as upper body strength.

Marcin Moroń, a researcher at the Institute of Psychology at the University of Silesia in Poland, designed a study to test whether relational aggression offers quantifiable reproductive benefits in a contemporary society. By focusing on actual fertility rather than dating proxies, his work aimed to test the evolutionary adaptiveness of covert hostility.

Moroń analyzed data from 1,497 Polish adults who participated through an online survey platform. The participants ranged in age from eighteen to eighty-one, averaging about forty-eight years old. Just over half of the respondents were women. Participants completed demographic surveys asking about their socioeconomic status, relationship status, and the number of biological children they had.

The participants also answered a series of questions assessing their disposition toward relational aggression. The survey divided these hostile behaviors into two distinct categories. One category measured aggression directed at peers, asking if participants would try to embarrass someone or threaten to withdraw their friendship to get their way. The other category measured aggression directed at romantic partners, such as intentionally trying to make a spouse jealous.

Moroń used statistical models called Poisson regressions to examine the relationship between these aggressive tendencies and the number of children participants reported. These statistical models are specifically designed to analyze count data, like the number of offspring. The models accounted for demographic variables including age, sex, socioeconomic status, and whether the respondent was currently in a romantic relationship.

People who reported higher levels of peer-directed relational aggression were found to be involved in romantic relationships more frequently than those with lower levels. After adjusting for age and socioeconomic factors, higher peer-directed aggression was associated with a higher number of biological children. The data showed this positive association between covert peer aggression and fertility for both men and women.

The study then isolated the participants who were currently involved in romantic relationships. Within this specific group, higher levels of romantic partner-directed relational aggression were also linked to having more children. When looking at simple statistical correlations, this specific association appeared primarily among men.

The formal regression models, which evaluate all overlapping variables simultaneously, did not confirm a firm difference between the sexes in this regard. The interactions between sex and relational aggression were not statistically significant in the final models. Because these gender differences were not robust, Moroń noted that the proposed explanations for these behaviors could apply equally to men and women.

Relational aggression might function as an evolutionary strategy for competing with members of the same sex. Lowering the social rank of a romantic rival can increase a person’s chances of attracting a desired partner. This strategy is known in evolutionary biology as rival derogation. Improved mating success through these tactics could eventually lead to a higher number of offspring over a lifetime.

Within an established relationship, relational aggression might serve as a tactic to retain a mate. Behaviors meant to manipulate a partner or deter outside rivals might stabilize long-term relationships, which generally predicts higher fertility. Alternatively, these aggressive behaviors might push a partner away. This would lead the aggressive individual to break up, find new partners, and potentially have children across multiple relationships.

The results of the study are based on a cross-sectional design, meaning the data was collected at a single point in time. This type of observational data prevents researchers from determining simple cause and effect. It is possible that being in a relationship makes people more relationally aggressive as they attempt to guard their partner, rather than the aggression initially causing their romantic success.

The study also relied on self-reported questionnaires. People might underestimate or underreport how often they use manipulative tactics because they want to appear in a favorable light to researchers. Using reports from peers or partners could provide a more objective measure of a person’s aggressive tendencies in future studies.

The observed effect of relational aggression on fertility was relatively small in magnitude. Factors like a person’s age and relationship status played a much larger role in predicting how many children they had. The research also lacked data on variables like voluntary childlessness and the use of contraceptives. Tracking these factors would reveal exactly how aggressive individuals navigate modern family planning.

Future research will need to explore these social dynamics over a continuous timescale rather than a single snapshot. Longitudinal studies could track individuals from adolescence through their reproductive years to see how aggressive strategies shift over time. Despite the limitations, the current findings suggest that subtle, covert aggression might continue to play a role in human reproductive success.

The study, “Relational Aggression and Lifetime Offspring: A Preliminary Study in a Large Community-Based Sample of Polish Adults,” was authored by Marcin Moroń.