Physical aggression boosts number of sex partners in men
Studies have found that among other things, sensation seeking, hypermasculinity, physical attractiveness, testosterone levels and sex drive, age at sexual initiation, childhood sexual abuse, and substance use are related to the lifetime number of sexual partners.
A study by Patrick Seffrin and Patricia Ingulli investigated attributes influencing the number of lifetime sex partners using data from 'The National Study of Adolescent to Adult Health'. This longitudinal national survey interviewed, during 1994-1995, adolescents (7th- through 12th- graders), then re-interviewed the same individuals in 3 more waves well into their adulthood.
The researchers measured the accumulation of sex partners over time by extracting data from items in the survey. The researchers also measured attributes of each individual in the sample that could be related to lifetime number of sexual partners - drug use, perpetration of crime and violence, drug dealing, gang affiliation, alcohol use, sexual coercion, potential for high socioeconomic status, intelligence, educational attainment, economic disadvantage, physical attractiveness, physical maturity, self-control, religiosity, and childhood physical/sexual abuse.
In line with previous research, attractiveness, drug and alcohol use were positively correlated with sexual behavior for for both men and women. Being married, being an "A" student, high self‐control, and high religiosity were associated with lower number of sexual partners.
Intelligence (in both sexes), and violence (in men) emerged as especially likely to boost the number of sex partners. Intelligence was consistently and significantly linked to all of the mating indicators for both sexes. Educational attainment and economic disadvantage were not significantly correlated.
The size of effect of violence on accumulation of sex partners in men was found to be comparable to that of intelligence. Violence was measured in the national survey using four items (questions valid for a year prior to survey) -
1. have you pulled a knife or gun on someone
2. seriously injured someone in a fight
3. gotten into a group fight
4. shot or stabbed someone
"To be sure of the effect of men's aggression on sex partner accumulation, changes in violence were examined in relation to changes in the rate at which sex partners were reported, revealing a significant statistical relationship. So, rather than solely being a byproduct of men competing against one another for mating opportunities, the relation between men's aggression and mating success shown here also suggests a preference among women for aggressive males."
Intelligence is a much sought after trait in romantic partners and is believed to have been strongly selected for during the Pleistocene (one hypothesis implicates sexual selection in humans evolving stronger intellects). The finding that violence is just as good as intelligence in accumulation of sex partners for men suggests that aggression may function as a costly Zahavian signal in the mating context. Read more about the study here.