Testosterone maxxing is all the rage – but when it comes to fatherhood, less might be more
Becoming a father naturally drops men’s testosterone levels. And the more involved they are, the more it drops.
Testosterone, a hormone often associated with masculinity, is currently a popular topic on social media. It's praised for its supposed benefits, such as building muscle, increasing wealth, and promoting sexual dominance. Even high-ranking officials like US Secretary of War Pete Hegseth have endorsed testosterone screening for service members over 30.
Health Secretary RFK Jr has also promoted testosterone replacement therapy as a solution to a perceived decline in American masculinity. Online, men are encouraged to check their testosterone levels and "maxx" their testosterone, pushing it to the highest possible level.
However, a new book by US clinical psychologist Darby Saxbe suggests that high testosterone isn't always beneficial. Saxbe's book, "Dad Brain: The New Science of Fatherhood and How it Shapes Men's Lives," draws on 20 years of research and her own studies to show how profoundly fatherhood changes men hormonally. The book argues that high testosterone levels don't equate to good fathering. It states that biological processes typically work as negative feedback loops, not as simple dials that can be adjusted.
The book points out that testosterone levels are influenced by a man's life and environment. Artificially increasing testosterone through injections or gels doesn't necessarily lead to more aggressive behaviors, competitiveness, or success. In fact, dominant and successful men often have higher testosterone levels due to situational factors like winning contests or facing challenges to their status. When these challenges arise, testosterone levels rise, while they decrease when losses occur.
One significant issue with high testosterone levels is that they can lead to a reduction in sperm production. The brain's signal that prompts the testes to produce sperm can be suppressed by excessive testosterone injections. In one trial involving 271 men, nearly two-thirds stopped producing sperm altogether, resulting in no pregnancies among their partners over a thousand months. Moreover, when administered in excess, testosterone can effectively prevent men from becoming fathers.
Saxbe's research also delves into the neurological impacts of fatherhood. She scanned the brains of 20 first-time fathers in Barcelona before their partners conceived and again two months after the birth. The fathers lost cortical grey matter volume, with deeper brain structures remaining unaffected. Another study of 38 first-time fathers, scanned throughout their partners' pregnancy and again six months after the birth, revealed that men who bonded most strongly with the unborn child and planned to take more parental leave experienced the most significant brain volume loss.
The downsized paternal brain, Saxbe explains, may process information more efficiently once the demands of parenting begin.
The changes in men's brains, both in grey matter volume and testosterone levels, signal a readiness to parent. Men who felt more bonded with their unborn children and planned to take parental leave showed more brain volume reduction. Furthermore, fathers experienced drops in testosterone before the baby's arrival, with levels around 17% lower at 36 weeks compared to 12 weeks.
These hormonal changes, which occur months before the sleepless nights associated with new parenthood, may indicate a shift in the men's biological systems, preparing them for the responsibilities of fatherhood.
Written by urgent.news from The Conversation AU's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
