The Purpose of Pendulous Boobies

Bonobo female - photo by © Hans Hillewaert / CC-BY-SA-3.0Speaking of articles that drive me nuts, it’s pretty safe to assume that any time scientists make a “discovery” about human reproductive evolution, I’m going to get annoyed. Like this recent article about the purpose of enlarged female breasts.

“Larry Young, a professor of psychiatry at Emory University who studies the neurological basis of complex social behaviors, thinks human evolution has harnessed an ancient neural circuit that originally evolved to strengthen the mother-infant bond during breast-feeding, and now uses this brain circuitry to strengthen the bond between couples as well. The result? Men, like babies, love breasts.”

Now, the best explanation I’ve heard, summarized rather bluntly, is that breasts resemble buttocks. In many primates, you see, females signal reproductive readiness through a swelling of the buttocks. This works great for quadrupedal animals, but when humans moved to bipedalism, that swelling became both inconvenient for locomotion, and relegated to a position well below eye level. Sure, plenty of men still like butts, but maybe there was an evolutionary advantage in having a second “butt” in, let’s say, a more ‘prominent’ position. This theory is supported, says author Christopher Ryan, by the fact that bonobos, which also show an inclination toward bipedalism, are the only other ape to feature human-like breasts.

So why does Larry Young think his theory is a better one?

“Young thinks it’s because we form monogamous relationships,* whereas 97 percent of mammals do not. “Secondly, it might have to do with the fact that we are upright and have face-to-face sex, which provides more opportunity for nipple stimulation during sex.”

See, there’s a problem here. You may not know it (because science textbooks, and apparently many scientists, still cling to this patriarchal notion) but human monogamy only arrived around 18,000 years ago, when agriculture and the idea of property ownership arrived and human men decided human women were part of the “property” they were going to own. Homo sapiens arrived in our current form closer to 200,000 years ago, and our ladies have been swinging pendulous breasts since the start–as, likely, did many of our bipedal ancestors and cousins.

It’s about time we stopped teaching children the mythology around the “monogamous human,” where women stay home and mind the children, men go out and hunt wild beasts, and pair-bonded women have to hold the attention of their instinctively promiscuous men. It’s bullshit, perpetuated by churches and others with a vested interest, and the result of feeding it to our children (aside from constant stress and ruined relationships when people feel they aren’t living up to the myth) is scientists who draw false conclusions based on wrong information.

If you want an accessible explanation of the reality behind human reproductive evolution, I highly recommend Sex at Dawn, co-written by Ryan and Cacilda Jethá, MD. It’s a fun read, with some mind-blowing revelations around human behavior, and it’s quite accesible to the layperson [puns may be intended]. I will warn you, though, if you’re one of those people clinging to the one-man-one-woman model of human reproduction, this book (like reality–sorry!) is likely to upset you.

* [emphasis mine]

Bonobo photo © Hans Hillewaert / CC-BY-SA-3.0


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