When you think about it, the male fixation with female breasts is completely disproportionate. Men will literally stop dead in their tracks and dismiss the entire world around them when suddenly presented with a perfect pair. The reaction is undignified — and even a bit pathetic. But why is this? And what does science have to say on the matter? The answer, say two biologists, may actually have to do with their intended function.
According to Larry Young and Brian Alexander, authors of the new book, The Chemistry Between Us: Love, Sex, and the Science of Attraction, it's not for the usual reasons given by evolutionary biologists. Writing in the Huffington Post, the authors reject the two prevailing theories on the matter.
First, they dismiss the suggestion that men are selecting for full breasted women on account of their ability to store lots of fat in their bosoms (they argue that "sperm is cheap" and men don't need to be picky). And second, they don't buy the notion that the transition from rear-entry to face-to-face sexual intercourse has anything to do with it, either. Instead, the authors suggest that there's only one possible explanation — one that relates to a mother's bond with her infant. They write:
When a woman gives birth, her newborn will engage in some pretty elaborate manipulations of its mother's breasts. This stimulation sends signals along nerves and into the brain. There, the signals trigger the release of a neurochemical called oxytocin from the brain's hypothalamus. This oxytocin release eventually stimulates smooth muscles in a woman's breasts to eject milk, making it available to her nursing baby.
But oxytocin release has other effects, too. When released at the baby's instigation, the attention of the mother focuses on her baby. The infant becomes the most important thing in the world. Oxytocin, acting in concert with dopamine, also helps imprint the newborn's face, smell and sounds in the mother's reward circuitry, making nursing and nurturing a feel-good experience, motivating her to keep doing it and forging the mother-infant bond. This bond is not only the most beautiful of all social bonds, it can also be the most enduring, lasting a lifetime.
Another human oddity is that we're among the very rare animals that have sex face-to-face, looking into each other's eyes. We believe this quirk of human sexuality has evolved to exploit the ancient mother-infant bonding brain circuitry as a way to help form bonds between lovers.
When a partner touches, massages or nibbles a woman's breasts, it sparks the same series of brain events as nursing. Oxytocin focuses the brain's attention to the partner's face, smell, and voice. The combination of oxytocin release from breast stimulation, and the surge of dopamine from the excitement of foreplay and face-to-face sex, help create an association of the lover's face and eyes with the pleasurable feelings, building a bond in the women's brain.
So there you have it — it all comes down to the chemicals in your brain. And it's true — oxytocin is the world's greatest molecule. Be sure to check out Young and Alexander's entire article as there's lots more.