Modern Wisdom

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The Painful Psychological Cost Of Becoming A Dad - Darby Saxbe - #1129

Explore episode Jul 27, 2026

Where this was said

How Fatherhood Changes Male Hormones

At 45:00 · chapter starts 38:50

The hormonal dimension of fatherhood is as well-documented as the neurological one, and Saxbe walks through it with the challenge hypothesis as the organising framework. Testosterone rises during mate competition — maximising opportunities to reproduce — and then adaptively falls once mating is accomplished and the strategy shifts from quantity to quality of offspring. The pattern holds across birds, rodents, primates, and humans. In new fathers specifically, the testosterone drop is linked to caregiving behaviour, not simply to the existence of a baby. The downstream effects are broadly health-protective: less risky driving, fewer fights, lower substance use, more attention to health checkups, greater investment in the pair bond. Saxbe and Chris discuss the irony of men who supplement testosterone in an attempt to signal masculinity, potentially suppressing the very adaptive shift that makes them effective fathers — with anecdotal reports from mothers suggesting the connection is real.

Science
The Challenge Hypothesis: Why Men's Testosterone Is Supposed to Drop

The Painful Psychological Cost Of Becoming A Dad - Darby Sa… · Jul 27, 2026 Science

The challenge hypothesis explains that testosterone rises during mating competition and then adaptively falls when the strategy shifts from maximizing babies to maximizing any given baby's survival. It plays out in birds, primates, rodents, and humans alike — fatherhood isn't a hormonal failure, it's a hormonal success.

Health & Fitness
Testosterone Supplementation May Sabotage New Dads

The Painful Psychological Cost Of Becoming A Dad - Darby Sa… · Jul 27, 2026 Health & Fitness

When men become engaged fathers, testosterone naturally drops — and that drop is adaptive. It reduces aggression, increases pair bonding, and promotes nurturing. Men who take exogenous testosterone may be overriding that system, and anecdotal reports from mothers suggest it shows up as reduced patience with their babies.

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