Eve Ate the Apple and Gave us the Obstetrical Dilemma, Right?
Eve ate the apple, and birth became painful for humans ever afterward.
The obstetrical dilemma is a concept that is pervasive in our culture and in our medical system. The idea is that human birth is “difficult” and painful because of either Eve’s curiosity or, in scientific land, because of two specific evolutionary changes. The first change was from using four limbs to using two for locomotion. Humans stand up on two legs (bipedalism), and the theory purports that this made the outlet of the human pelvis smaller. The second evolutionary change was the intense need for social interaction to teach our young how to survive. Other animals rely more on instinct and less on teaching/learning to know how to find food and shelter. This need for social interaction and the use of language required a bigger brain housed in a larger skull… thus humans had to start birthing large-brained babies from smaller pelvic outlets resulting in more difficult births.
In academic language, it sounds like this: “The hypothesis holds that antagonistic selection for a large neonatal brain and a narrow, bipedal-adapted birth canal poses a problem for childbirth” (Dunsworth, et al., 2012).
Here’s the thing.
This theory, very widely accepted, is based on a lot of assumptions that were never tested or clarified.
It also arrived on the scene at a time when (mostly male) physicians were attempting to wrest control of birth away from (mostly female) midwives and move birth from homes to hospitals. The “obstetrical dilemma” fit the needs of the dominant group. Birth is difficult, perhaps they could go so far as to call it “dangerous!”, and therefore birthing people need expensive “experts” with access to the latest technology to save their lives.
If you want to know a LOT more about this history, I recommend reading a 2003 classic article by Dana Walrath called, “Rethinking Pelvic Typologies and the Human Birth Mechanism.”
In this post, I want to question just two of the assumptions that underpins the obstetrical dilemma theory. The first is the idea that labor and birth are longer, more difficult, and more painful for humans than for any other animal, including our primate relatives. But the fact is that at the time this theory was finding wide acceptance, scientists had extraordinarily few observations of primate birth to use for comparison. This was before the time of, say, Jane Goodall (who studied gorillas) or Dian Fossey (who studied chimpanzees) or Galdikas (who studied orangutans). We did not know until 1971 that orangutans were fruit eaters, so imagine what we knew of their reproductive experiences?
In Walrath’s article, she details some of what we have come to learn about primate birth experiences. Turns out that primate birth can be long and difficult, too. Their infants also need to rotate in order to emerge (something we thought was uniquely human because of the obstetrical dilemma). Some primates have had documented labors as long as 60 hours! Researchers do not usually get to observe primate birth up close, so we actually do not know much about the birth positions of primate infants (for example, do they face upwards or downwards? Occiput posterior or anterior?).
A second assumption is that humans give birth to young “earlier” in their gestation than other animals because of their large brains. We often say in the natural birth world that human babies are born about “three months too early” and we have the phrase “fourth trimester” to explain how helpless human infants are in the early months. But, again, guess what? We decided this was true before we really investigated it. As Dunsworth, et al. write, human gestation is longer than that of chimpanzees, gorillas, and orangutans. And not only is gestation absolutely longer, if we control for the relationship between the body mass of the birthing person/primate and the length of pregnancy, humans look like we have a LONGER pregnancy!
In academic language, that sounds like this: “At 38–40 wk, on average, human gestation is absolutely longer than that of Pan (32 wk) and Gorilla and Pongo (37–38 wk). Controlling for the positive relationship between maternal body mass and gestation length in primates (n = 21 species; r2 = 0.56; Fig. 1 and Fig. S2), humans are second only to Pongo in their gestation length. Human gestation length is 37 d longer than expected for a primate of similar body mass, relatively longer than either Gorilla or Pan. So not only is human gestation not truncated, as comparisons controlling for adult brain size might suggest, but the data indicate that gestation has increased in the hominin lineage.”
One takeaway I have is this: Birth works very well, evolutionarily speaking! Humans are successful at reproducing and producing live offspring. Our bodies have been designed through evolutionary pressures to give birth well and at the right time, just as other animals’ bodies are designed to give birth well and at the appropriate time. If we are going to take any lessons from our primate relatives, it is probably fair to take this lesson: We can do it!
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