New study suggests fatherhood lowers men’s testosterone levels

Summary of story from Medical Express, September 12, 2011

A new study has provided conclusive evidence that fatherhood lowers a man’s testosterone levels, suggesting that they may be biologically wired to care for their offspring.

“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.

“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.”

The study followed a large group of men who were not fathers to see 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 co-author Lee Gettler.

“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.

“Fatherhood and the demands of having a newborn baby require many emotional, psychological and physical adjustments.

“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.