Testosterone dips on becoming a father

http://uk.lifestyle.yahoo.com/testosterone-dips-on-becoming-a-father.html

It seems it’s not just women who are biologically wired to nurture their babies — fathers also go through hormonal changes to help them care for their children.

In many species of mammal the male takes a major role in caring for offspring and now new research points to humans having the same capability.

A new study has found that upon becoming a father a man’s testosterone levels decrease. While testosterone helps the males of species compete for a mate it is not necessarily conducive to fatherhood, hence the reduction in levels.

Although previous studies have pointed to this phenomenon they have been too small to be conclusive and have not identified whether fatherhood reduced testosterone levels or whether men with lower levels of testosterone were more likely to become fathers.

But this study carried out by scientists at Northwestern University in Chicago, US and the Office of Population Studies Foundation in the Philippines followed a group of 624 men in the Philippines, aged between 21 and 26 years old, for more than four years. None were fathers to start with so the changes in their testosterone levels on becoming a father could be measured.

The researchers found that men with higher levels of testosterone were more likely to become fathers but once they had their levels dropped substantially. “Our findings suggest that this is especially true for fathers who become the most involved with child care,” said Lee Gettler, an anthropologist and co-author of the study.

The emotional and physical changes a new father goes through can be significant and the study found that fathers often go through a very large, but temporary, dip in testosterone when they first bring home their newborn baby. “Our study indicates that a man’s biology can change substantially to help meet those demands,” said Gettler. 

And there appears to be another interesting side-effect to these results which may explain why single men often have poorer health than married men and fathers. The lower testosterone levels may help protect the men against some chronic diseases as they age.

“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 Kuzawa, co-author of the study and associate professor of anthropology in the Weinberg College of Arts and Sciences, and 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.”