Why Do Women Have Breasts, Anyway?
9:45 am, May 11th | by Florence Williams
If there’s one thing starlets like Jayne Mansfield and Mae West understood, it was the power of their ample endowments. In her 1959 memoir, Goodness Had Nothing to Do with It, West writes that beginning in her teens, she regularly rubbed cocoa butter on her breasts, then spritzed them with cold water. “This treatment made them smooth and firm, and developed muscle tone which kept them right up where they were supposed to be.” West has good company in doling out ridiculous breast-enhancing tips. On the Internet, you can find creams, pills, pumps, pectoral exercises, even a YouTube video on how to master the boob-inflating “liquefy tool” in Photoshop.
In our culture at least, big breasts get a lot of attention. So I’m told. I display, or rather, don’t display, the traditional average American size, a B cup. Women I know tell me that having large breasts is like walking around with a neon sign hanging around their necks. Men, women, small children, everyone stares. The eyes linger. Some men pant. It’s not surprising that some anthropologists have called breasts “a signal.” Breasts, they say, must be telling us something about how fit and mature and healthy and maternal their owner is. Why else have them?
All mammals have mammary glands, but no other mammal has “breasts” the way we do, with our pleasant orbs sprouting out of puberty and sticking around regardless of our reproductive status. Our breasts are more than just mammary glands; they include a meaty constellation of fat and connective tissue called stroma. To be functional for nursing an infant, a mammary gland need fill only half an eggshell. Big breasts are not required. Along with bipedalism, speech, and furless skin, breasts in their soft stroma-filled glory are one of humanity’s defining characteristics. But unlike bipedalism and furlessness, breasts are found in only one sex (at least most of the time). And those kinds of traits, as Darwin pointed out, often evolved as sexual signals to potential mates.
But signals of what, exactly? And does this explain how and why humans won the boob lottery? Many scientists seem to think so, and they have devoted large chunks of their careers to answering these questions. One thing is clear: it’s rather fun trying to find out. It’s not especially hard to design studies showing that men like breasts. What’s much trickier is proving that it actually means anything in evolutionary terms.
I was hoping the answers might lie with the creative experiments of Alan and Barnaby Dixson, a father-son team of institutionally supported breast watchers. Both based in Wellington, New Zealand, together they’ve published papers on male preferences for size, shape, and areola color and on female physique and sexual attractiveness in places such as Samoa, Papua New Guinea, Cameroon, and China. Alan, a distinguished primatologist and former science director of the San Diego Zoo, brings a specialty in primate sexuality to their shared project, while Barnaby, a newly minted Ph.D. in cultural anthropology, has a knack for computer graphics and a fresh zeal for fieldwork.
I first met Barnaby on a blustery fall day in Wellington. At twenty-six, his curly auburn hair falling around the collar of a fisherman’s sweater, he was very earnest. He walked around with a distracted air and wrinkled brow, and often misplaced things, such as parking receipts. It’s not easy being a sex-signaling expert. “Sometimes people think I’m using the government’s money to look at breasts. They misunderstand what we do,” said Barnaby, who’s tall and gangly and speaks with a crisp British accent. As Barnaby pointed out, in places like Samoa, which is now very missionized, it can be a delicate matter asking men to describe which types of breasts they prefer. He said some men think he’s “a perv” and get very angry. He avoids men who have been drinking. And in the academic world, grant money can be hard to come by when there are things like breast cancer research to fund. “I probably should have been a doctor,” he said. “But I’m quite squeamish really.”
Barnaby’s latest digital experiment employed an EyeLink 1000 eye-tracking machine and a suite of specialized software. The sixty-thousand-dollar piece of equipment lives in a small, nondescript room labeled “Perception/Attention Lab” in the psychology department at Victoria University. It looked like something you’d find in an optometrist’s exam room. You place your chin in the chin cradle and your forehead against the forehead rest. Then you look through little lenses. Instead of seeing an alphabet pyramid, though, your eyes meet images of naked women flashing on a computer screen. If all eye exams worked like this, men would surely get their vision screened in a timely fashion.
On the day I visited the lab, an ecology graduate student named Roan was game to volunteer. Wearing jeans and a baggy T-shirt, he patiently looked through the eye-tracker as Barnaby calibrated the machine. Then Barnaby explained the test. Roan would be looking at six images, all of the same comely model, but digitally “morphed” to look different. Roan would have five seconds to view each image, and then he’d be asked to rank it on a scale of one to six, from least attractive to most, using a keyboard. The images would have smaller and larger breasts and various waist-to-hip ratios. These two metrics, the breasts and the so-called WHR (essentially a measure of curviness), are the lingua franca of “attractiveness studies,” which is, believe it or not, a recognized subspecialty of anthropology, sociobiology, and neuropsychology. The theory is that how males and females size each other up can tell us something about how we evolved and who we are.