Paternity dramatically reduces testosterone levels in men
Last reviewed: 16.10.2021
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People, it seems, are the only creatures on Earth who cultivate young animals for twenty years or more. For men, this is such a shock that, apparently, they developed a biological mechanism that helps to cope with the need to spend energy on offspring.
A new study showed that as a father, a man undergoes a sharp decline in testosterone levels: they say, aggression and readiness for competition are less useful when it comes to raising children.
Previous studies have made it clear that among young fathers testosterone levels are lower than those of men of the same age who do not have children. But no study so far could answer the question: did the birth of a child lead to a decrease in testosterone levels or did men with low hormone levels become devoted husbands and caring fathers?
In order to understand the causes and consequences, anthropologists Lee Gettler, Christopher Kuzawa and their colleagues from the Northwestern University (USA) and the University of San Carlos (Philippines) tested testosterone levels in men participating in the longitudinal study of the inhabitants of the Philippine city of Cebu. It began in 1983 with three thousand women who were pregnant at the time, followed by monitoring the overall health, nutrition, medical care of children who now have their own children, so the project has crossed the boundaries of one generation.
In short, a large group of men has been studied for almost thirty years - since birth, which is unprecedented. In 2005, scientists measured the morning and evening content of testosterone in the saliva of about six hundred men and repeated the analysis in 2009.
It turned out that men with high testosterone levels became more often devoted partners and dads, after which there was a sharp drop in hormone levels compared to childless peers - 26% in the morning and 34% in the evening, whereas in "nepap" age reduction was 12% and 14% respectively.
The study also showed that testosterone levels were the lowest among those who spent the majority of their time on childcare. Low levels of the hormone also correlate with the age of the children: the strongest fall was recorded in the fathers of newborns.
"The drop in testosterone levels appears to be a normal biological restructuring that helps men rethink their priorities when children appear," says Mr. Kuzava. Other studies, by the way, have shown that men with high testosterone levels are more likely to have problems in marriage and divorce. In one experiment, such men felt less sympathy and less need to react to the crying of the child.
Thus, the classical hypothesis, according to which men developed solely to be food-earners, is questioned. As you can see, fathers are biologically predisposed to taking care of children. In other words, paternity is the normal aspect of masculinity.
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