My Best Friend’s Girl: Is the "Bro Code" scientific?

My Best Friend’s Girl: Is the "Bro Code" scientific?

Could the “bro code” be part of our DNA? A new study has found that men’s testosterone levels drop during contact with the wives and girlfriends of their closest male pals.

Illustration by Ryan Peltier

The researchers concluded that reduced “competition among friends and allies may be biologically embedded” within humans—in other words, that men are hardwired to avoid inappropriate contact with their friends’ mates.

But don’t jump to conclusions, warns Abraham Morgentaler, the author of Why Men Fake It: The Totally Unexpected Truth about Men and Sex and the founder and director of Men’s Health Boston. “As a physician who has raised and lowered testosterone in thousands of men, I am always somewhat amused by studies like this one that suggest male behavior is little more than the result of minute-by-minute changes in testosterone levels.”

In men under 40, these levels “undergo marked diurnal variation,” sometimes soaring twice as high in the morning as in late evening “without any obvious change in behavior.” Moreover, testosterone levels vary weekly and seasonally.

Although steep drops in testosterone level “may cause symptoms of decreased sexual desire . . . it is critical to understand that the testosterone changes reported in this study are far too small to produce the kinds of behavioral changes they report. Life is more complicated than this. Men are not simply a reflection of their testosterone levels.”

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