UCLA

Lift more weights, find more mates

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By Meg Sullivan

Published Jul 9, 2007 10:21 AM


The researchers, who are associated with UCLA's Center for Behavior, Evolution and Culture, say that their findings on muscularity are consistent with research findings on the secondary sexual characteristics of other animals, such as the attention-getting tail feathers of male peacocks.

"Everybody knows that testosterone is a hormone that promotes strength in men, but less well-known is the fact that the hormone is also associated with poorer immune system functioning," Frederick said. "Secondary sexual characteristics are thought to have evolved as indicators of mate quality because they demonstrate an ability to flourish in the face of what's really a drag on the system. Males in good enough shape to withstand the deleterious effects of immunosuppression have to be especially fit and are therefore more likely to transmit fitness to their offspring than less well-endowed males."

Muscle attraction: It's evolutionary

"Evolutionary scientists have long maintained that exaggerated secondary sexual characteristics — such as large muscles in men — are cues to genes that increase the viability of offspring or their reproductive success," Haselton said. "In an age when medical advancements play such a large role in the survival and health of children and so many people use contraceptives, it's not clear whether these genes continue to offer reproductive benefits. But women today are still attracted to muscular men, just as their ancestors would have been, because that's how we've evolved."

Interestingly, women in the study seemed to be on to muscular men. When presented with six standardized silhouettes of men ranging from brawny to slender, 141 undergraduate women consistently identified the most muscular ones as not only less likely to commit but also more volatile and domineering. In the study, the women rated "toned" guys — the physical type two notches down from "brawny" — as the most sexually attractive.

"Moderate muscularity demonstrates that men are in good condition, but they're not so overloaded with testosterone that they are volatile, aggressive and dominant," Frederick said. "Just based on their experiences, women seem to be able to weigh good and bad male traits."

Still, in a study by Frederick and Haselton of 82 college coeds, most women reported that their short-term partners were more muscular than their long-term ones. They characterized their long-term — and presumably less muscular — partners as more trustworthy and romantic than their one-night stands or brief affairs.

"This suggests that the sweet-guy approach works better for less muscular men," Frederick said. "The muscular men don't need to put in this kind of effort, especially for a short-term relationship."

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