Fathers Wired to Provide Offspring Care; Study Confirms That Testosterone Drops Steeply After Baby Arrives

ScienceDaily (Sep. 13, 2011) — A new Northwestern University study provides compelling evidence that human males are biologically wired to care for their offspring, conclusively showing for the first time that fatherhood lowers a man's testosterone levels.

The effect is consistent with what is observed in many other species in which males help take care of dependent offspring. Testosterone boosts behaviors and other traits that help a male compete for a mate. After they succeed and become fathers, "mating-related" activities may conflict with the responsibilities of fatherhood, making it advantageous for the body to reduce production of the hormone.

"Humans are unusual among mammals in that our offspring are dependent upon older individuals for feeding and protection for more than a decade," said Christopher W. Kuzawa, co-author of the study and associate professor of anthropology in the Weinberg College of Arts and Sciences. He also is a faculty fellow at the Institute for Policy Research at Northwestern. "Raising human offspring is such an effort that it is cooperative by necessity, and our study shows that human fathers are biologically wired to help with the job."

Past studies showing that fathers tend to have lower testosterone levels were small and not conclusive regarding whether fatherhood diminished testosterone or whether men with low testosterone in the first place were more likely to become fathers. The new study takes a novel approach by following a large group of men who were not fathers and seeing whether their hormones changed after becoming fathers.

"It's not the case that men with lower testosterone are simply more likely to become fathers," said Lee Gettler, a doctoral candidate in anthropology at Northwestern and co-author of the study. "On the contrary, the men who started with high testosterone were more likely to become fathers, but once they did, their testosterone went down substantially. Our findings suggest that this is especially true for fathers who become the most involved with child care."

The new study's findings also suggest that fathers may experience an especially large, but temporary, decline in testosterone when they first bring home a newborn baby. "Fatherhood and the demands of having a newborn baby require many emotional, psychological and physical adjustments," Gettler said. "Our study indicates that a man's biology can change substantially to help meet those demands."

The authors also suggest that their findings may provide insight into one reason why single men often have poorer health than married men and fathers. "If fathers have lower testosterone levels, this might protect them against certain chronic diseases as they age," Kuzawa said.

The study followed a group of 624 males aged 21.5 to 26 years old for 4.5 years in the Philippines.

The study was published Sept. 12, 2011, in the Proceedings of the National Academy of Sciences.

The study's co-authors, along with Gettler and Kuzawa, are Thomas W. McDade, professor of anthropology and Institute for Policy Research faculty fellow, Northwestern University, and Alan Feranil, director, Office of Population Studies Foundation, University of San Carlos, Cebu City, Philippines. The research was funded by the National Science Foundation and the Wenner Gren Foundation.

Fathers wired to provide offspring care; Study confirms that testosterone drops steeply after baby arrives

I heard about this today too. Makes sense but...

I think they (the media) give testosterone too much credit.

"but baby! my testosterone levels were sky high when your sister came over and propositioned me! I had no control over my body!"

And I don't think lower testosterone is going to make your old man give a shit about what you learned at school today either.

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Well sure, it's going to be very hard to translate a chemical effect like this into specific behaviours, statements, or thoughts. I'd also expect that, like everything else, the effect varies in different individuals. But if it reduced, for example, risky behaviours, that would make it more likely for men to be around to provide care.

Still and all, its a fairly significant finding, especially given the recent fashion for casting men as seed-spreaders with no investment in their kids. Clearly their own bodies don't think so.

Originally Posted by contracycle

Still and all, its a fairly significant finding, especially given the recent fashion for casting men as seed-spreaders with no investment in their kids.

I would imagine that you can apply both strategies at once, though. But I do agree that it does contradict the image given so far by some other research.

That being said, the risky behaviour bit is somewhat known. There was a funny piece on single CEOs and the volatility of their equity's returns. And, yep, single CEOs are more risk takers than married ones and that was verified because, within the same industry, their returns were more volatile...

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