Science Reveals Men's Ideal Female Breast Size Linked To Relatively High Estrogen Levels, Fertility

Men, similar to babies, are infatuated by women's breasts, for various reasons. Babies see breasts as life sustaining, supportive, and nurturing, while men see them as “fun,” and indicative of child-bearing qualities. Now, researchers at Prague's Charles University believe men's ideal breast size is driven by the same evolutionary drive — fertility.

The study, published in the journal Evolution & Human Behavior, found men prefer shapely, perkier boobs to those that are larger, and potentially sag over the years.

Read: What A Man's Breast Size Preference Says About His Personality Traits

This is surprising, since previous research suggests bigger breast size indicates higher estrogen and estradiol levels, meaning large-chested women were more fertile.

For example, in a 2004 study, women with a relatively low waist-to-hip ratio and large breasts had about 30 percent higher levels of estradiol. This means if there are 30 percent higher levels, they're about three times more likely to get pregnant. Naturally, men are subconsciously attracted to women who are most fertile for reproduction.

“Cross-culturally, males are hypothesised to prefer breast morphology that indicates both high potential and residual fertility,” wrote the researchers in the study.

A total of 267 men from four different countries, including Brazil, Cameroon, the Czech Republic, and Namibia, were questioned on their breast preferences. They were showed two sets of images of varying breast size and firmness. The findings revealed individual preferences for breast size varied, but the majority of the participants preferred medium-sized, followed by large-sized breasts, and small breasts. However, when it came to firmness, men from across all four countries strongly favored this trait.

Therefore, breast morphology, not size, may reveal to a man whether a female is especially fertile.

Bra Science finds men's ideal breast size for women is linked to fertility. Photo courtesy of Pixabay, Public Domain

The researchers explain the shape and size of human female breasts are so unique among primates because of their permanent fat deposits. They theorize female humans' different morphology arose as a direct result of male sexual selection. In other words, breast size and shape were intended to serve as an indicator of potential fertility.

The preference for shapely, and perkier breasts is tied to how breasts become less firm with age and parity. This means breast shape could also serve as an indicator of "residual fertility," or menopause. The loss of perkiness and fertility may be what drives men to prefer medium-sized, firm breasts over larger breasts.

Read: The Average Bra Size In America

Men rely on visual cues when choosing the woman who would be the healthiest, fittest mother for their child. This sheds light on the evolutionary explanation for why men love breasts — they rely mostly on visual cues to inform their decision.

Bigger may not always be better when it comes to breast size, but size is a relative concept. The researchers do seek to explore the relationship between firmness and health. Breasts can serve as a good indicator of fertility, but what exactly firmness says about a woman's health has yet to be explored.

Moreover, men are generally happy to stare at breasts no matter the size. In a 2009 eye-tracking study, researchers in New Zealand expected men to spend more time looking at larger-than-average boobs compared to smaller-than-average. However, they found variations in breast size did not affect men's "number of fixations and dwell times."

After all, most men see other qualities as more important when it comes to female attraction than breast size.

Source: Jan Havlíček J, Třebický V, Valentova JV et al. Men's preferences for women's breast size and shape in four cultures. Evolution & Human Behavior. 2016.

See Also:

How Your Breast Size Speaks Volumes About You

Everything You Need To Know About Women's Breasts, According To Science

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