When I set out to write a book about the natural history of breasts, I knew I'd have to answer some awkward questions about my book topic. At a friend's book party, I entered a discussion with an elderly man who is slightly hard of hearing.
"What's your book about?" he politely asked.
"Breasts," I ventured.
"Breasts," I said louder. Some people turned to look at me.
"No, breasts!" By this time I was shouting and gesturing in an unmistakable way.
You get the idea.
Within my awkward topic of breasts, it soon became clear I'd have to tackle the awkward question of evolution. How did these wonders appear? At first, I thought this would be relatively straightforward. I figured that if all mammals had them, how complicated could it be? But this turned out to be one of the most contentious discussions in a book full of them. I soon learned that human breasts, in all their fatty, pendulous glory, are incredibly unique in the animal kingdom. Other primates have swollen mounds while lactating, but ours show up in puberty and stick around regardless of our lactational status.
Now, everyone knows men like breasts. So perhaps it shouldn't come as a surprise that this obvious fact has long driven the central theory of breast evolution. It goes like this: They must be designed by nature to attract males! They are like the peacock's tail: meant for display. Breasts are so fun to look at that they must tell us something important. They must be "signals" of fertility, health, and a worthwhile roll in the hay.
This theory was best articulated by Desmond Morris, the famous British anthropologist and author of The Naked Ape, published in the 1960s. Many female primates signal sexual readiness (their estrus) with swollen buttocks. He believed that breasts essentially mimicked the bum, but on the chest since humans walk upright and interact face-to-face. Breasts needed to be big, he argued, to signal sexual availability all the time since constant sex was necessary to keep male hunters coming home at night and sharing their meat. Basically, Morris projected the 1950s suburban ideal back through evolutionary history, and breasts helped him out.
But a few decades later, women in the field rose to challenge this "signaling" view of breasts. They pointed out, for example, that early human females actually procured many of their own calories. What if, some asked, soft, round breasts aren't really for men at all? What if they evolved to help babies and the women themselves survive? After all, breasts store fat, an essential and sometimes scarce ingredient throughout our evolution. Human babies are born plumper than any other primate. Mothers needed to be fatter to sustain pregnancy and large, human infant brains needed more fat. Hmmm. Perhaps breasts exist to facilitate fat deposition.
Not very sexy, is it?
The fat theories may sound reasonable, more so, in fact, than the signaling ones, but the breasts-are-about-sex theories still dominate the field today. In fact, you won't hear the alternate theories in many college anthropology classrooms. Many guys are, shall we say, too attached?
I recently ran into an old friend from college, and we started talking about my book topic, which is always a good ice-breaker. His eyes lit right up. This man is Generation X, an enlightened hipster, married to a career woman, etc. But as soon as I started my spiel about the breast-evolution debate, he cut me off, practically snorting over the arguments of the feminist anthropologists.
"Give me a break!" he shouted. "Of course breasts evolved to attract males!" By this point, we were descending a corporate-lobby escalator, and attracting some attention. "Why else would every single male in pretty much the entire world love breasts?!"
Here's the funny thing, though. It's only those men who really, really like breasts who think this must be a universally shared condition. Men like, I imagine, Desmond Morris. In fact, scholars have had a very difficult time proving that all heterosexual men across cultures have a thing for breasts (that hasn't stopped many from trying). Because some men, at least while answering questionnaires, shrug them off in favor of other female features (and some of these seem pretty weird, like small feet). Moreover, even among men who love breasts, there's a huge variety of preference for size and shape. This presents a big headache for anthropologists trying to prove the organs' worth as signals of anything meaningful.
Over lunch the other day with my friend Christopher, I explained my frustration with the old-school boobs-are-for-men theories, and instead of cutting me off, he wholeheartedly agreed. "Those guys need a knock in the head!" he said. Christopher, it turns out, is a leg man. Oh, and he's a family doctor in an under-served community, where he wishes more women would try breast-feeding their babies.
Ultimately, it will probably be impossible to know exactly when or why breasts evolved. There is no fossil evidence for breasts. We don't exhume Lucy and know her cup size.
But the debate matters. It colors how we view breasts, who they're really for, and how we treat them. The origin discussion is worth having, and maybe someday we'll appreciate breasts in more ways than we do now. In fuller, softer, more ponderous and pendulous ways.