Yogurt Makes Mice Sexy

Not only does yogurt make mice slimmer; it also makes them sexier.

When I saw the headline “Yogurt Makes Mice Slimmer, Sexier” linked from another story at ABC Mews, I presumed it was a link to The Onion. Or a paid promotion from the yogurt industry. Instead, it was an actual article from their Medical Unit blog.

Scientists studying the power of probiotics to fight obesity got more than they bargained for: Not only does yogurt make mice slimmer; it also makes them sexier.

Studies in humans suggest eating yogurt may help stave off age-related weight gain. But Massa­chusetts Institute of Technology researchers Eric Alm and Susan Erdman wanted to know why. ”Maybe it has to do with the healthy bacteria that live in our guts,” said Alm, an evolutionary biologist, explaining how there are 10 times more bacteria in the body than human cells. “Maybe probiotics in the yogurt have something to do with the effects on weight.”

To test the theory, Alm and Erdman fed one group of mice a normal mouse diet and another group the same diet with a mouse-sized serving of vanilla yogurt.

“One of the first things we noticed was their fur coat,” said Erdman, assistant director of comparative medicine at MIT. “It was so thick and shiny; shockingly shiny.”
But shiny fur wasn’t the only thing that set the yogurt-eating mice apart from their siblings: They were also slimmer, and the males had “swagger.”

“We knew there was something different in the males, but we weren’t sure what it was at first,” Erdman said. “You know when someone’s at the top of their game, how they carry themselves differently? Well, imagine that in a mouse.”

A lab technician would soon discover what was giving these males their sexy strut. ”She noticed their testicles were protruding out really far,” Erdman said. It turns out their testicles were 5 percent bigger than those of their non-yogurt eating counterparts, and 15 percent bigger than those of mice on a diet designed to mimic “junk food” in humans. And in this case, bigger was better.

“Almost everything about the fertility of those males is enhanced,” Erdman said, explaining how yogurt-eating males mated faster and produced more offspring. “There were legitimate physiological differences in males fed probiotics, not just the extra sexiness.”

And let’s not forget the ladies. Female mice that ate yogurt were even shinier than the males, and tended to be better moms to their larger litters.

I repeat: This is not a parody news story from The Onion. Apparently, MIT employs a team of  mouse hotness experts who spend their days measuring mouse balls and making judgments about the swagger and motherly qualities of the sexy little rodents. All in the interests of science.

On a side note, Googling for pictures with the phrase “sexy mouse” returns very few pictures of mice, sexy or otherwise.

And, certainly, no discussion of this topic would be complete without some classic AC-DC:

FILED UNDER: Food, Health, Quick Takes, Science & Technology
James Joyner
About James Joyner
James Joyner is a Security Studies professor at Marine Corps University's Command and Staff College and a nonresident senior fellow at the Scowcroft Center for Strategy and Security at the Atlantic Council. He's a former Army officer and Desert Storm vet. Views expressed here are his own. Follow James on Twitter @DrJJoyner.


  1. Mark Ivey says:



  2. John Burgess says:

    Wow! The next time I need to sex-up some mice, I’m really going to put this advice to good use!

    As for human carry-over… well, supposedly yoghurt lets people of the Caucasus live crazy-long lives, but I’m not sure they’d qualify as human sex pots.

  3. Brett says:

    We laugh, but then watch out – it might have some weird and very useful human applications down the line. I still remember how that study on the sex lives of centipedes saved the cattle industry billions.

  4. Peacewood says:

    Could you elaborate, Brent? I’m genuinely intrigued.

    And no, I am NOT googling “centipede sex”.

  5. Brett says:

    My bad – it was the sex lives of screw-worms:

    Ask and ye shall receive