Smaller the Testes, Better the Father: Study

A latest study shows that fathers with small testicles take better care of their children.

The study conducted by anthropologists at Emory University found that the brains of these fathers also respond quickly when showed their children's photo.

For the study, the researchers scanned brains and testes of 70 fathers of children aged between one and two with the help of magnetic resonance imaging (MRI). The fathers and mothers of the children were told to fill out a questionnaire about the fathers' dedication toward raising their children.

The participating fathers were also shown the photos of their kids. Dads rated as better for child care by their partners had more activity in an area of the brain that acts like a reward system. Participants who had larger testes were found to be least involved in taking care of their children.

The testes, in addition to producing testosterone in males, also produce sperm. "Testes volume is more highly correlated with sperm count and quality than with testosterone levels," study lead author Jennifer Mascaro said.

The research also confirmed previous results of a study that said fathers involved in child care have lower levels of hormone. However, they also found that link between the size of the testes and child care was not exactly similar. "The fact that we found this variance suggests personal choice," said Emory anthropologist James Rilling. "Even though some men may be built differently, perhaps they are willing themselves to be more hands-on fathers. It might be more challenging for some men to do these kinds of caregiving activities, but that by no means excuses them."

Rilling also said that men who were more involved in taking care of their children "their testes shrink." "Some research has shown that boys who experience childhood stress shift their life strategies," he said. "Or perhaps fatherless boys react to the absence of their father by adopting a strategy emphasizing mating effort at the expense of parenting effort."