Sorry Sir Mix-a-Lot: Men prefer spinal curvature, not big butts

Abbey Hull for redOrbit.com – @AbbeyHull4160

Step aside Sir Mix-a-Lot, because a new study from The University of Texas at Austin found that men’s preferences for women with “buns” on their curved backside connects with prehistoric influences.

Published in Evolution and Human Behavior, men prefer women with a “theoretically optimal angle of lumbar curvature”—or a 45.5 degree curve from back to buttocks—in their mate.

“This spinal structure would have enabled pregnant women to balance their weight over the hips,” said David Lewis, UT Austin alumnus and Bilkent University psychologist. “These women would have been more effective at foraging during pregnancy and less likely to suffer spinal injuries. In turn, men who preferred these women would have had mates who were better able to provide for fetus and offspring, and who would have been able to carry out multiple pregnancies without injury.”

The research contained two studies:

The first had 100 men rate the attractiveness of multiple images displaying manipulated spinal curves ranging across the natural human spectrum. Looking at the vertebral wedging, a basic spinal feature that can influence the curve in women’s lower backs, researchers found that men were most attracted to the images of women with the 45 degree lumbar curve.

Vertebral Wedging

Women with (a) less vertebral wedging at the third-to-last lumbar vertebra (modal L3 depicted), and (b) greater wedging, resulting in a more acute angle of lumbar curvature. (Credit: The University of Texas at Austin)

The second study took research a step further, asking whether men preferred this 45 degree angle because it indicates a larger buttocks or simply because of the spine angle itself. Two hundred men were given groups of images of women with varying buttock size and vertebral wedging, but all with the 45.5-degree curve. Men consistently preferred women who possessed the optimal spinal curvature, regardless of how big their buns were.

Range of Lumbar Curvature

This is a schematic of a complete series of stimuli. (Credit: The University of Texas at Austin)

“This enabled us to conclusively show that men prefer women who exhibit specific angles of spinal curvature over buttock mass,” study’s co-author Eric Russell, visiting researcher from UT Arlington stated.

“What’s fascinating about this research is that it is yet another scientific illustration of a close fit between a sex-differentiated feature of human morphology—in this case lumbar curvature—and an evolved standard of attractiveness,” said study co-author David Buss, a UT Austin psychology professor. “This adds to a growing body of evidence that beauty is not entirely arbitrary, or ‘in the eyes of the beholder’ as many in mainstream social science believed, but rather has a coherent adaptive logic.”

Sir Mix-a-Lot disagrees, however, offering his rebuttal to us on Twitter.

[STORY: Some turtles can breathe through their butts]

So ladies (yeah?), you can do side bends or sit ups, but this evolutional stance won’t be changing for a while. However, studies like these expand our approach and knowledge for both natural and social sciences—it’s a win-win, don’t you think?

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