On a recent episode of the Dear Hank and John podcast (in which two brothers give “dubious advice”, I recommend it!) a listener sent in a question about why human infants were so useless. And even though both of them have children of their own, they didn’t really know what the answer was so they gave it their best shot: (paraphrasing here) because of bipedalism, women’s hips are too narrow and the baby needs to come out prematurely otherwise they won’t fit.
If you’ve read the earlier parts in this series debunking the Obstetrical Dilemma, you can imagine my epic head shaking and eye-rolling. I had already had this post waiting in the wings but I decided to rework the intro and title when I realized that lay people who have never heard the phrase “obstetrical dilemma” will forward it without even being aware of it. So, why are newborn humans useless?
The phrase “childbearing hips”, besides being extremely cringey in any context, is a misnomer. It’s a byproduct of the kind of thinking that went into the Obstetrical Dilemma: in order to give birth women traded in bipedal efficiency for wider hips. It’s a hypothesis that was and is widely assumed to be true. But you know what they say about making assumptions? … As it turns out, pelvic width has nothing to do with bipedal efficiency, nor is it a constraint for fetal head growth or childbirth. Continue reading
In western culture, there is a long tradition of women suffering through labor… something about an apple? Throughout the history of obstetrics, theories have been tossed about to explain humanity’s apparently unique difficulties in childbirth. One of the more recent is the Obstetrical Dilemma which posits that the female pelvis is too narrow to give birth to human babies (without a lot of professional, technical intervention, and even then… ) but too wide (wider, on average, than a male pelvis) to be efficient.
Racist Roots with a side of Misogyny
The OD hypothesis came into being around the same time that hospital birth was becoming the norm in the United States. In 1949, Aldoph H. Schultz, from the John Hopkins University School of Medicine in Baltimore, Maryland published a paper titled Sex Differences in the Pelves of Primates about the pelvic measurements of a variety male and female cadavers from a selection of primate species. Among these non-human primate species are chimpanzees, gorillas, and negroes.
Yes, you read that correctly. And if you aren’t horrified, I am not sure I want you reading my blog.
Schultz believed that black people represented a different species of primate, describing their pelvic measurements as more animalistic than whites, as a means of explaining why they had easier births. His research was used to justify the lack of medical care available to pregnant black women across the U.S. but even more so in the Jim Crow south. Continue reading
Humans, like the other Great Apes, are physiologically riders; breast milk composition is not suited to parking infants for long periods between feeding (Ross). For this reason among many others, our species has had to carry our babies with us wherever we go. Unfortunately, humans find carrying infants more difficult than our evolutionary cousins for three reasons: lack non-grasping feet and body hair, physically helpless infants and, most importantly for this post, the relative size of our infants.
Non-human apes in the taxonomic family Hominidae (literally means “Great Ape” and makes me think of Charlotte’s Web’s “Some Pig” but I digress) have smaller, more precocious babies than humans. Adult gorillas, for example, are significantly larger than adult humans, yet their newborns are about half the size of human newborns. Chimpanzees, which are our closest extant evolutionary relative and have a similar adult body weight to us, give birth to newborns that are around 3% of their adult size, while humans have newborns that are around 6% of adult size (DeSilva). At what point since our common ancestor with chimpanzees, did hominins start having bigger babies? Continue reading