New research looking to fathering habits and testicle size
suggested that bigger may not be better when it comes to the day-to-day
raising of small children.The research involved 70 US men of varying ethnicities -- most
were Caucasian, five were Asian and 15 were African-American. All were
the fathers of children aged one to two. The larger the volume of their testes, the less the men were involved in
daily parenting activities like changing diapers, said the study by
researchers at Emory University in Georgia. In comparison, men with smaller testes showed more nurturing activity in
the brain when shown pictures of their children, and also were more
involved in their children's upbringing, according to surveys answered
separately by both the fathers and their female partners. All the men in the study were aged 21-55 and lived with the biological mothers of their children. Most were married. "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 diapers, bathing children, preparing meals, taking
them to the doctor and things like that," said lead author James
Rilling, an associate professor of anthropology. The study sought to test an evolutionary theory that holds that people and animals are either built to breed or to nurture. The findings support the notion that human beings have a limited amount
of energy to invest in reproductive efforts -- so either they put energy
into producing offspring or into raising it. If you invest more energy in parenting you have less available for mating and vice versa," explained Rilling. Since the testes are where sperm is made, and their size can be linked
to the amount produced, the researchers said their study is unique and
the first of its kind. Previous studies have shown a link between high testosterone levels and
lower parental involvement as well as divorce and infidelity. The Emory
team also analyzed testosterone levels and found the same inverse
relationship to parental involvement in their study. "Other people have looked at testosterone and parental behavior but as
far as we know we are the first to look at testes size and parental
behavior and we think we are getting at something different," said
Rilling. "We are suggesting that men with larger testes are more built for a
mating effort strategy and as a consequence are less built for investing
in children." Researchers used functional MRI scans to analyze brain activity when the
men were shown pictures of their toddlers and also of strangers'
children. To assess the men's daily parenting involvement with their young
children, scientists asked the men and their female partners to
separately fill out questionnaires. The volume of the testes was measured in a voluntary MRI scan, to which 55 of the 70 men agreed. Still, the researchers could not say for sure whether testes size caused
the difference in fathering behavior, or if perhaps the act of becoming
a father might have caused the testes to shrink in some men. Urologist Joseph Aluka, who was not involved in the research, said he
commonly sees men with smaller testes in a certain context. "The guy who comes in with smaller testes is more likely to have greater
difficulty with getting his wife pregnant," Aluka, an assistant
professor at New York University Urology Associates, told AFP. If such men end up being more involved as parents, "maybe these guys
struggled to have kids and appreciate the experience a little bit more,"
Aluka said. "I wouldn't be surprised if just a few participants in this study
fundamentally affected their data because it is a small study," said
Aluka, describing the findings as "a stretch." The study appeared in the Proceedings of the National Academy of Sciences.
Source-AFP
Source-AFP
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