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According to a study conducted by UNLV professors, men who get married and have children are more likely to experience reductions in testosterone.
“The bottom line is ‘What does testosterone do?’ It does all the things you think it does,” said Dr. Peter Gray, assistant professor for the UNLV Department of Anthropology. “It promotes libido, validates interactions, a sense of self-worth, all the kinds of things that engage successfully in the world around us eventually acquire reproductive opportunities.”
In 2000, Gray and others began looking at the affects of testosterone in more detail in the United States as well as elsewhere in the world.
All studies have found U.S. men involved in long-term relationships, such as marriage, have lower testosterone than their single counterparts.
Gray wanted to expand his study by posing the question, “When you step outside the U.S., is that the case?”
Gray and researchers Peter Ellison of Harvard University and Benjamin Campbell of the University of Wisconsin, Milwaukee sought to answer this question by researching Ariaal men in a rural Kenyan pastoralist society and men of urban Jamaica.
This study builds on work previously done in Beijing, China, as well as work Gray researched for his dissertation.
Grey looked at the effect that polygamy, or having multiple spouses, in two Kenyan populations had on testosterone levels. He compared men with two wives to other men in Kenyan costal community.
“They had testosterone levels higher than other guys. Why was that? That was another unresolved question,” Gray said.
He went back to this issue in his study on pastoralists in rural Kenya.
“No longer we were on the Kenyan coast on a small urban community like in my earlier study. Now you’re in a small scale rural pastoralist society,” Gray said.
With the different culture came different results. Men who were older with multiple wives had lower testosterone levels than other men.
“In this rural Kenya pastoralist society we found the guys with one wife had lower testosterone than the single guys,” said Gray. “There has been unpublished data in urban Bangladesh with no differences between single guys, married guys and married fathers”
In his Jamaican study, fathers had lower testosterone than single men.
In a study done in pastoralist society Tanzania, there were no differences between fathers and single fathers. Because it was a hunter-gatherer society where fathers would be more involved and invested in their children, fathers still had lower testosterone than single fathers.
“[In general] you see a push especially towards dads with lower testosterone than single dads in some of those studies,” Gray said. “It’s harder to review because there isn’t a whole lot published yet.”
Gray’s research is among the first done on this subject of hormones, marriage and fatherhood. His research builds on previous studies done by the U.S. government on Vietnam veterans exposed to Agent Orange. The study was done mainly to track the veterans’ health, yet incidentally, it also tracked testosterone levels and men’s relationship status.
“This is very much a new literature,” Gray said.
In the Jamaica study, other hormones, such as oxytocin, vesopressin and cortisol, were also studied.
Gray said the future of hormones studies will focus on these instead of testosterone.
An example of this is prolactin, which regulates milk production and functions in both males and females. In birds such as pigeons, both mother and father can produce milk to feed their young. Also, wolves that care for their young have elevated prolactin.
“There are studies suggesting that species that form longer bounds and paternal care is in part regulated by vasopressin,” Gray said. “So, in one hand we want to separate all the testosterone work, and then there’s the other hormone work as well.”
In understanding the general effects of hormones, Gray said one should simply ask every-day men if they feel a physiological difference since marriage.
“In some ways I think this puts a physiological substrate into things men might already report they feel,” Gray said. “I think if you ask around enough you’ll find out that that is the case. There’s a social context I think interprets why or why not they have lower testosterone associated with some of these long-term relationships.”
Next year, Gray hopes to expand his research to women in Jamaica.
Heidi Manlove, a senior anthropology major, has been a student assistant for Gray for a year. As a part of Gray’s study, she has researched behavioral endocrine mechanisms of polycystic ovarian syndrome.
From her research, she sees greater emphasis on hormones usually associated with males, such as testosterone, in women.
“Most people do not realize that women have testosterone hormone levels as well as estrogens,” Manlove said. “The imbalance of testosterone levels in women may influence mood, cognition, as well as weight and reproductive problems.”
By Shelly Mar, Advertising Assistant Manager
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