The Nature-Nurture-Nietzsche Newsletter

The Nature-Nurture-Nietzsche Newsletter

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The Nature-Nurture-Nietzsche Newsletter
The Nature-Nurture-Nietzsche Newsletter
Testosterone, Masculinity, and Men's Health

Testosterone, Masculinity, and Men's Health

Why this misunderstood hormone may matter more than you think

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Steve Stewart-Williams
Aug 27, 2025
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Testosterone, Masculinity, and Men's Health
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I recently spoke with Ari Blaff of the National Post about testosterone, masculinity, and men’s health. Among other things, we discussed what the science says about testosterone’s role in shaping sex differences, how the hormone affects men’s health across the lifespan, and why I’m not a fan of the APA Guidelines for Psychological Practice with Boys and Men. What follows is a lightly edited transcript of our conversation.


Ari Blaff: How solid is the research on testosterone when it comes to influencing sex differences?

Steve Stewart-Williams: For many sex differences - especially those we also see in other animals - it’s pretty solid. We’ve got good evidence, for instance, that prenatal testosterone helps explain why, on average, men are more aggressive than women, why they’re less parental, and why they’re more interested in things and less interested in people.

An interesting nuance is that, while the links between prenatal testosterone and male-typical behavior are fairly strong, those between current blood levels of testosterone and male-typical behavior are not. They’re weak at best, except perhaps at very low levels of the hormone.

But although the research is solid, it’s not beyond criticism. One limitation is that hormone studies often have small samples, which raises the risk of both false negatives and false positives, with the false positives more often finding their way into print. Another limitation is that much of the human research is correlational rather than experimental, which leaves the results somewhat up in the air.

Still, for many sex differences, the case for testosterone’s involvement is strong - much stronger than the case against.

Ari Blaff: Are the findings broadly accepted among academics?

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