In a recent report in the scientific journal Nautilus, Richard Gutierrez Bribiescas, a professor of anthropology, ecology, and evolutionary biology at Yale, zeroes in on why those of us with a Y chromosome—and this goes for not just humans, but all mammalians—seem to be in the crosshairs of natural selection: It’s because we have more testosterone.
Yes, the very same hormone that boosts your metabolism, builds your muscles, fires up your libido, and gives your skin that ethereal glow typically only seen in Equinox ads is actually what kills you earlier than your wife. As Bribiescas writes, having steady, healthy levels of testosterone correlates (obviously) with a more robust level of physical fitness—but that higher T has also been linked to everything from the common cold to cancer.
In other words: evolution has spoken, and it says you’re more useful to the human race living a strong life than a long one. “In essence,” Bribiescas says, “sex trumps birthday candles.” Here are five ways that Bribiescas explains that testosterone may be the cause of males’ earlier demise for humans and other animals across the whole of the animal kingdom. And if that doesn’t scare you enough, be sure to read up on if testosterone replacement therapy is right for you.
We can argue for the rest of our days on which gender is superior. But when it comes to fighting illness and disease, the fairer sex takes the cake. Research of avian, reptilian, and mammalian populations has shown that creatures with higher levels of testosterone get infected more frequently and have more difficult time fighting off those infections.
On the other hand, estradiol, a hormone women possess in spades (men have little of it), boosts immune function. So not only are women less likely to get sick, when they do get sick, they’ll be better at fighting it off. The math checks out on this: women, after all, have to stay healthy to reproduce, while men—from a biological perspective—don’t.
In 2006, ornithologists experimented with the testosterone levels in birds. (It’s unethical to experiment life-or-death scenarios in humans, so science must turn to the animal kingdom.) Birds with increased testosterone were able to fight off the competition and father more babies. Sounds great, right? Well, again, there’s a catch: those birds put on less fat and, as such, had a far more difficult time surviving until the next breeding season. In short, pushing yourself to the limit leaves you exposed to danger down the line.
Elsewhere in the animal kingdom—in Australia—exists a marsupial called a quoll. Male quolls tend to live for about a year, sometimes less. Female quolls, however, live up to three times as long. Ecologist Jaime Heiniger observed that, during mating rituals, male quolls experience a sharp increase in testosterone. This leads to “intense bouts of mating” (awesome), but is also tied directly to male quolls’s shorter lifespans (not awesome). Out in the animal kingdom, having less fat makes an organism more “vulnerable to food shortfalls and infection,” writers Bribiescas. So, maybe it’s best the expression is “screwing like rabbits” and not “screwing like quolls.” If that former screed piques your interest, read up on the 10 best everyday sex-drive boosters for men.
Testosterone replacement therapy hasn’t been around long enough for rock-solid conclusive evidence on this one, but the maybes and likelys are still out there—and they’re not exactly comforting. One 2014 study showed that, in older men on testosterone, after 90 days, the probability of a non-fatal infarction—not a typo, that means heart attack—increased significantly. So if you’re planning on taking testosterone supplements, you should be sure to build a heart of steel.
Well, this one’s a doozy: the “man” hormone might cause the cancer most commonly found in men. A 2010 study published in the American Journal of Human Biology found a correlation between testosterone levels and rates of prostate cancer. Societies with higher testosterone levels happened to also show higher rates of prostate cancer. More research needs to be done, of course, but that’s some damning evidence. After all, as we’re all well aware, prostate cancer is quite the ordeal.
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