From PEOPLE Magazine Click to enlarge
Fashion may be fickle, but men are not—at least when it comes to judging beauty, says Devendra Singh, a professor of psychology at the University of Texas at Austin. Singh studied the works of early romantic poets and discovered that a woman's hourglass figure ("thy breasts are like ripe pomegranates"; "whose waist is little as a wand") has been fawned over through the ages. "What we consider attractive has remained constant—it's an hourglass figure, a woman with a low waist-to-hip ratio," says Singh, whose study appeared in a British scientific journal. "A woman could be walking away from you, where you can't see her face or breasts, but you can still see her shapeliness and say, 'What a sensual, beautiful woman.'"

BEYONCE KNOWLES

Knowles, 25, talks about returning to her bootilicious best after losing 20 lbs. for Dreamgirls.

"When I did Dreamgirls, I did lose my curves. I remember coming home and seeing my friends and they were like, 'Who are you?' I like when I'm a little curvy."

FERGIE

The singer, 32, explains her Fergalicious humps.

"I am not what's trendy now in Hollywood—the zero zero. I definitely have curves. I think that's what a natural woman should look like. I love running stairs. It's really great for the glutes, and I always like having a nice shape back there."

CHRISTINA AGUILERA

The 26-year-old chart-topper is currently strutting her stuff on her Back to Basics tour.

"I was always lean growing up, she says. Once I hit my early 20s, I started to fill out. I really got excited. It's fun for me to take on that womanly shape. I definitely wasn't upset about gaining those curves! Now I love being able to fill out the corsets and accentuate that look."

ISLA FISHER

The Aussie actress, 31, who is engaged to Borat's Sacha Baron Cohen, laughs about going from geek to gorgeous.

"I got called Dumbo about my ears, and my brothers used to say that I had a fat face and bingo wings [Australian for flabby arms]. But I think the trick is to hide your flaws."

DITA VON TEESE

The 34-year-old burlesque dancer shares the inspiration for her bombshell bod.

"When I was little, I remember watching Jayne Mansfield in The Girl Can't Help It and making a promise that when I grew up I was going to have curves like that: the cinched-in waist, the big bust and those ample hips that just popped off the screen. I've never made a secret about having my breasts done. It's something I'm proud of. The message I want to get out is that anyone can do this. Honestly, without my bag of tricks, I am pretty ordinary—it's just that I have a pretty nice bag of tricks."