Why Do Women Have Breasts, Anyway?
9:45 am, May 11th | by Florence Williams
The eye-tracker doesn’t lie. It would show exactly where on the body Roan was looking while making up his mind. As Barnaby had explained to me earlier, the machine would measure the travel of Roan’s pupils within one-hundredth of a degree, and would record how long his gaze lingered on each body part. “The beauty of the eye-tracking machine is that it allows you to get some measure of behavioral response. You can measure, literally, the behavior of the eye during attractiveness judgment,” Barnaby had said.
Roan began staring and ranking. The whole thing took a couple of minutes. He looked a little flushed when it was over.
He stuck around to see how he did. Barnaby called up some neat graphics and computations. A series of green rings overlay the model; they represented each time Roan’s eyes lingered for a moment. Some of the rings were on her face, a few on her hips, a whole bunch on her breasts. Barnaby explained them as he reviewed the data. “He starts at the breasts, then looks at the face, then breasts, then pubic region, midriff, face, breasts, face, breasts. Each time the eye rests longer on the breasts.” Roan spent more time gazing at the breasts than elsewhere during each “fixation.” He rated the slimmer images with large breasts as most attractive.
In other words, Roan behaved just as most men do, and just as Jayne Mansfield knew he would. She could have saved Victoria University a chunk of change.
Barnaby’s eye-tracker results may be obvious, but to a scientist, data are key. Barnaby was preparing to publish his study in a journal called Human Nature. He believed the work backs up a relatively well-accepted hypothesis that breasts evolved as signals to provide key information to potential mates. That’s why men’s eyes zoom in on breasts within, oh, about two hundred milliseconds of viewing an image. That’s milliseconds. “The overall theory is that youth and fertility are important traits when men and women in ancestral times were selecting a partner,” said Barnaby. “So it makes sense they’ll select for traits that signal mate value, youth, health, fertility.” He believes men find breasts useful. Because men liked these informative, novel, gently pendulous orbs—which originally sprang up in the accidental way all new traits do—they selected mates accordingly. The breasty women were the ones who mated most, or mated with the best males, and so the trait was passed down for all to behold. In the world according to Barnaby, that’s pretty much the end of the story.
I wondered whether Roan subconsciously sensed that cache of health and youth information in a few seconds of ogling.
“Do you tend to be a breast guy?” I asked him.
“Good question.” Roan is a South African who spends his academic time studying rhinos. “Yeah, but not majorly so. It’s not like I’m obsessed, like some guys I’ve met who tend to go on about it. But yeah, I definitely don’t have any problem with them.”
I couldn’t help feeling peeved by the real-world relevance of the eye-tracking study. A man looks at a woman’s hips and breasts for five seconds and decides whether or not to mate with her? Was that how it worked in our deep evolutionary past? Was it how it worked now? And even if it were, did it really explain why we have breasts in the first place?
“When you’re meeting a woman, you’re hopefully looking at more than just her breasts,” I said to Barnaby and Roan.
Roan blushed and laughed. “Of course! Cheers!”
“That’s an important point,” interjected Barnaby. “You’re not just going to stare at her breasts.”
“Some people do,” said Roan.
Barnaby felt a need to rescue the conversation. “This is an artificial experiment. It measures what you might call a first-pass filter, just things that are immediately apparent. Then later, when you’re meeting and talking, so many other things factor in, like personality, religious background, socioeconomic status.”
“Sense of humor?” I asked.
“Yeah,” said Roan. “Of course, of course.”