London ? The curves of Playboy centerfold models have gradually flattened over the last 50 years, giving way to a more androgynous look, European researchers suggest.

Analyzing every Playboy centerfold since the first in 1953, they found the models’ weight hadn’t changed much over time, but busts and hips had diminished, while waists had become less tapered.

The study, published this week in the traditionally lighthearted Christmas edition of the British Medical Journal, does not offer much interpretation of the trend and experts warn against jumping to conclusions.

Does it mean the male idea of female attractiveness has changed over time — that men now prefer a less curvaceous woman, despite their protests that “heroin chic” is not sexy?

Or is it simply that Playboy is now out of touch with what men find attractive?

Playboy spokesman Bill Farley acknowledged the curves on the centerfolds had changed.

“In the 1950s and into the ’60s, the cultural norm was more of the hourglass figure — Marilyn Monroe, Jayne Mansfield. That was reflected in the pages of Playboy. As time has gone on and women have become more athletic, more in the business world and more inclined to put themselves through fitness regimes, their bodies have changed, and we reflect that as well,” he said.

“But I would think that no one with eyes to see would consider playmates to be androgynous,” Farley said.