14 DAY TRIAL // Don't blame it on the age, it's marriage the one that makes a man less?male. Married/father males have been found to have significantly lower testosterone levels, as found by two new studies made at the University of Nevada, Las Vegas (UNLV), and led by anthropology professor Peter Gray. These researches are amongst the first carried outside North America, and studying facts from a cross-cultural perspective.
"As the scientific community begins to understand more about the biology of man, the better able we are to examine other psychological and behavioral outcomes, including the elevated risk of postpartum depression among men and the potential negative effects of testosterone supplementation on paternal investment and care", said Gray.
One research was made in East Africa, among the Ariaal shepherds in Northern Kenya. The team compared testosterone levels between single men, monogamous men, and polygamous men. Testosterone levels were assessed from saliva samples coming from 205 men aged over 20.
Similar to North American men, monogamous Ariaal men presented much lower morning and afternoon testosterone levels compared to their bachelor counterparts of similar age (20-39). But older polygamous Ariaal men also had lower testosterone levels than their counterparts married to just one woman.
This means that among older men, the decrease in testosterone doesn't stop with one wife and that social status and wealth - rather than sex drive and other testosterone-linked behaviors - make men marry more than one wife. The team believes this is due to the fact that married men don't have to compete for a woman any longer. "Testosterone levels are lower among married men probably because they are investing less in mating effort", Gray added.
This is clear in Ariaal men because of their "aloof" marital system: husbands and wives just have sex together, their activities being extremely separated, and men are minimally involved in childcare. Out of 203 married Ariaal men, only 3 were emotionally involved in their relationship with their wives.
The other research was made in Jamaica and investigated the link between fatherhood and hormones testosterone, prolactin, oxytocin, cortisol and vasopressin in 43 Jamaican men aged 18-40, assigned to three categories: single, biological fathers engaged in visiting relationships and biological fathers living with their youngest child.
Testosterone levels were much lower in visiting Jamaican fathers than in bachelors. The link between testosterone and fatherhood, first found in Canada, seems to be found worldwide. Prolactin levels in the case of bachelors were much smaller than those found in visiting fathers involved in a 20-minute session with their children. Increased prolactin levels could be connected to a closer interaction father-child. Among fathers, vasopressin levels were negatively and strongly linked to the age of the male's youngest child.