Every Friday on the blog, I answer people’s questions about sex, love, and relationships. This week’s question comes from a reader who wanted to know:

“Why are straight guys into breasts? Does it stem from them having been breastfed as children?”

Great question! I’ve heard this Freudian sort of explanation before (i.e., that men’s fondness for breasts stems from them having been nourished by their mothers’ breasts as infants); however, I don’t really buy it. I mean, if it were true, wouldn’t we expect that women and gay men would be just as interested in breasts?

That said, we don’t truly know the answer to your question; however, many theories have been offered, and almost all of them point to an evolutionary explanation. One such possibility is genital echo theory, which holds that women’s breasts did not become a major factor in attraction until human beings started walking upright [1]. The basic idea is this: before humans started walking on two legs, men’s primary source of visual excitement was a woman’s buttocks. However, when humans stood up, the buttocks was no longer displayed as prominently. Consequently, the breasts are theorized to have became bigger and more pendulous in order to mimic the visual appeal of the buttocks. This theory makes intuitive sense when you consider that cleavage bears a pretty striking resemblance to the rear end, right?

An alternative theory is that men evolved a preference for breasts because stimulating them enhances bonding with a female partner [2]. The basis for this theory stems from the fact that most women find breast and nipple stimulation to be sexually pleasurable. Indeed, some women find nipple stimulation so pleasurable that it can even lead to orgasm in and of itself! However, such stimulation also causes the release of oxytocin in the brain. As you may know, oxytocin is a hormone that facilitates bonding between humans. For instance, studies have shown that oxytocin plays a role in bonding between mother and child during breastfeeding, as well as between partners during sexual contact. Some scientists have argued that men developed an attraction to breasts precisely because breast and nipple stimulation activate this neurochemical bonding system that brings couples closer.

Certainly, these aren’t the only theories out there. For instance, I have also heard it argued that straight men like breasts because, in our evolutionary past, having full breasts was a sign that a woman had reliable access to food (breasts are, after all, a storehouse for fatty tissue) and, thus, could help ensure the survival of her children. Consistent with this idea, some research has actually found that men with the lowest socio-economic status preferred women with the largest breasts [3]. This suggests that when men don’t have the resources to provide for any children they might produce, they look for female sex partners who do.

That said, all of these theories are far from definitive and are complicated by a few factors. For one thing, not all straight men are into breasts. Moreover, that there are big cross-cultural variations in terms of what men find attractive about the female body. Although there’s still a lot we don’t know, most scientists seem to agree that men's fascination with breasts likely has evolutionary roots.

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[1] Fisher, H. E. (1992). Anatomy of love. New York: Fawcett Columbine.

[2] Young, L., & Alexander, B. (2012). The chemistry between us: Love, sex, and the science of attraction. New York: Penguin.

[3] Swami, V., & Tovée, M. J. (2013). Resource security impacts men’s female breast size preferences. PloS one, 8(3), e57623.

Image Source: iStockphoto.com

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