Erectile dysfunction (ED) is pretty much a misnomer if you ask Toby Kohler, M.D. He ought to know. Kohler, a professor of urology at the Mayo Clinic and also director of Men's Health for the clinic's hospital system, said that the ability to achieve and maintain an erection naturally falls off as men age, so this event is less a "dysfunction" and more a matter of being alive.

Basically, the older you are, the less likely you are to experience strong hard-ons.

The younger you are, however, the more likely that ED is a big, blinking danger signal for cardiac issues, according to work done by Mayo researchers that's since been replicated by multiple studies, including one published in 2012 in the American Heart Journal. "The penis is the most powerful predictor of heart disease we have," Kohler pointedly stressed, and if you're under age 60, the signs of ED