It takes a big set of cojones to be a good dad, right? Contrary to what one might think, researchers say it may actually be smaller testicles which make a man a good father.
To study the link between testicle size and parenting skills, a team of Emory University anthropologists used fliers and Facebook ads to recruit 70 local fathers between the ages of 21 to 43. All of the fathers had children between the ages of 1 and 2 and lived with both the child and the mother.
In order to assess how well the participants’ testicle sizes were correlated with their involvement as a parent, the researchers measured the men’s testosterone levels and their testes volume. Since testes size is an indicator of the quantity and quality of sperm, the authors considered men with larger testes to be more inclined towards mating than parenting. The men were then given brain scans while they viewed either pictures of their own children or of strangers. And, the men’s response to this test was used as a surrogate measure for their level of parenting involvement.
To add an additional set of data, the researchers also questioned the mothers about their perception of their partner’s involvement in parenting, rating how frequently he took over parenting tasks such as bathing, changing and feeding. They also asked the men the same questions.
What they found when they examined the data was that when the fathers with smaller testicles and lower testosterone viewed pictures of their children they had a higher level of brain activity related to nurturing than did the fathers at the other end of the spectrum. And, they were also more likely to participate in childcare tasks.
The authors believe that something called Life History Theory may provide an explanation for this phenomenon. According to this theory, evolution optimizes resources toward either mating or parenting in order to produce the largest number of healthy offspring. So, some men may be hardwired to primarily mate, reproduce and move on, while other men may be more likely to invest time and effort in raising their children. From a purely biological perspective, both patterns of behavior exist because both are viable strategies for producing large numbers of healthy children.
However, in an interview with British newspaper The Guardian, the authors clarified that being well-endowed physically does not mean that a man will automatically be a bad father. Humans are complex creatures and there is more to being a parent than your biology. Even if parenting does not come naturally to a man, it is possible that he can make a conscious decision to do better.
Study author Jennifer Mascaro also noted that it may well be that rather than testicle size influencing parenting, the reverse might be true: nurturing behavior might shrink testicle size. The way the study was constructed there was no way to determine causation, only that the two variables – testicle size and level of paternal involvement with offspring – were somehow linked to each other.
The study was published online ahead of print on September 9, 2013 in the journal Proceedings of the National Academy of Sciences.
Written By: Nancy Schimelpfening