There's this feeling held by every not-so-good-looking person (and when I say "every not-so-good-looking person," I really mean me) that attractive people have it made.

After all, good-looking people are more intelligent, more persuasive, are better at sales, have better careers, and, of course, wind up in relationships with other good-looking people.

But maybe we're just rationalizing. Or maybe we're a tad bit bitter, and envy makes us resent the idea that they have it easier. So we assume they don't work as hard. And we even assume that when the chips are down, and the tough need to get going, the good-looking people won't get going, because deep down inside they're soft.

And then we find out (and when I say "we," I really mean me) that our assumptions are wrong.

According to Erik Postma, a biologist at the University of Zurich, exceptional endurance is highly correlated with good looks. "Facial attractiveness signals endurance performance," Postma says, and to make it worse, "This suggests that human-endurance capacity has been subject to sexual selection in our evolutionary past." (Great. Do we--and when I say "we," I really mean me--need yet another reason to envy the fit and attractive?)

Postma reached that conclusion by gathering up headshots of 2012 Tour de France riders taken with the same basic lighting and background. He had participants in the study, 75 percent of whom were women, rate each photo for attractiveness. Then he matched those ratings with each rider's performance in the Tour.

And he did cool science-y stuff like determining whether the women used a hormonal contraceptive and the start date of their last menstrual cycle to see if their "level of fertility" had any impact on their ratings. (Gotta love science.)

The result? The riders who finished in the top 10 percent in the race were rated an average of 25 percent higher in terms of looks than the riders who finished in the bottom 10 percent.

In short, in a sport where endurance is everything, good-looking riders tend to perform better. Which means good-looking people aren't soft.

Sure, they may have it easier--at least in most situations--but, evidently, they're also capable of working harder and longer.

So go ahead and hire that good-looking salesman. He may not just outperform the rest of your staff. He may outwork them, too. Same with that good-looking programmer. She may not only be smarter; she may also be able to out-all-nighter your top all-nighters.

And who knows--maybe that's why good-looking salespeople tend to perform better. Maybe their success isn't based largely on looks.

Maybe they also work longer and harder.

Great: Back to the self-delusional rationalization drawing board.