Young men who take a greater interest in babies tend to show a lower increase in testosterone in response to sexually explicit material than men who aren’t as interested in babies, according to a new study published in the journal Psychological Science.
“Our findings show there is a strong mind-body connection: Liking or not liking babies is related to how a man’s body — specifically, his testosterone — responds to sexual stimuli,” explains Dr. Dario Maestripieri of the University of Chicago, lead researcher on the study.
“These results suggest that even before young men make actual decisions about marriage and children, one can distinguish between individuals who are more fatherhood-oriented and those who are less fatherhood-oriented.”
According to evolutionary life-history theory, there is a trade-off between a man’s ability to invest resources in mating and his ability to invest in parenting. The researchers hypothesized that testosterone, the primary sex hormone in males, may be the physiological mechanism underlying this tradeoff.
If this is the case, men who are more fatherhood-oriented and follow a “slow” life-history strategy would show less testosterone reactivity to short-term mating cues than men with a “fast” life-history strategy.
The study involved 100 young heterosexual men, mostly university students, and all of them childless. The participants completed a 12-item questionnaire that gauged their interest in babies and how they would respond to babies in various scenarios.
They also completed a 20-item survey that assessed their life-history strategy. On the survey, the participants rated their level of agreement with statements like “I have to be closely attached to someone before I am comfortable having sex with them” and “I often get emotional support and practical help from my blood relatives.”
After completing the questionnaires, the participants provided a baseline saliva sample. They were then left alone in the testing room to watch a 12-minute video featuring explicit erotic content. A saliva sample was taken once the video was over, and again 10 minutes later.
The findings showed that young men with a greater interest in babies tended to report a stronger orientation towards family and long-term relationships (a “slow” life-history strategy) compared with men who were less interested in babies.
Significantly, men who were more interested in babies tended to show relatively smaller increases in testosterone in response to the sexually explicit video. This association was not influenced by participants’ relationship status.
There was no evidence of a link between baseline testosterone levels and interest in babies, indicating that the results were not related to testosterone function more generally but were specific to reactivity to sexual stimuli.
“Young men who don’t like babies as much get more physiologically aroused by visual sexual stimuli; this makes sense from a life history perspective,” said Maestripieri. “These men ‘live on the fast lane.’ They are attracted to and aroused by novel sexual partners and are ready to take advantage of new sexual opportunities when they present themselves.”
“By contrast, young men who like babies more are less sexually aroused by novel sexual stimuli (for example, erotic content), but they presumably enjoy sex more in the context of stable monogamous relationships with partners they know well. We think that showing these mind-body connections is very novel and very exciting,” Maestripieri said.