Why less is more: small testes, better dad
September 10, 2013, 10:48 am Yahoo!7
Put down the rulers, fellas, testicle size is indicative of good parenting.
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Size matters when it comes to a father's testes
Never mind penis size, a US study has shown that it's the testes that dominate in the world of parenting.
You read correctly: scientists have shown that testes volume is inversely correlated with parental caregiving, meaning that men with larger testes are significantly more likely to be poorer fathers than their mates with average sized testicles.
The study, published in Proceedings of the National Academy of Scientists suggests that there may be a biological basis for parenting ability in men after all and that those with smaller testicles are more nurturing towards infants.
This is linked to an evolutionary principal called life history theory which states that there is a trade-off between males who invest their effort into mating with females rather than investing time in parenting or rearing offspring, the scientists said.
The research involved 70 US men who lived with their partners and young children aged one to two. They were questioned on the day-to-day rearing of their children and analysed for brain activity when shown photographs of their children.
While not an absolute finding (some bigger-balled men bucked the trend!) lead author James Rilling, an associate professor of anthropology, said the variance "suggests personal choice. Even though some men may be built differently, perhaps they are willing themselves to be more hands-on fathers," he said.
"I wouldn't want to say that men with large testes are always bad fathers but our data show a tendency for them to be less involved in things like changing nappies, bathing children, preparing meals, taking them to the doctor and things like that," he said.
Dr Rilling went on to say that it could as men become more involved fathers, their testes shrink. "Environmental influences can change biology. We know, for instance, that testosterone levels go down when men become involved fathers."
Researchers said that along with being linked to higher testosterone levels and sperm counts, large testes also correlate with increased promiscuity, marital breakdown and divorce.
