Marshall Brain's Blog

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This article on CNN reports that otherwise healthy women are increasingly electing to have C-sections to deliver their babies. Since C-sections are more expensive, insurance companies are unlikely to embrace this trend. And some doctors are not too excited either. In the article is this quote: "When people say, 'I'm going to do something that's more dangerous to my health, more dangerous to my baby's health,' it seems to me our values are getting out of whack completely about giving birth," said bioethicist Art Caplan.

Let's ignore the monetary, legal and ethical implications of C-sections and look at them from a different angle -- an evolutionary angle. Right now, about 25% of all births are C-sections. Evolution has a tendency to take advantage of changes like that in the environment. What will evolution do with the opportunities that widespread C-sections present?

For example, think about a baby's head size. Right now, a baby's brain is about as big as it can get in order to have any chance of passing through the birth canal. Nature already does some rather remarkable things to try to fit as much brain as it can through the canal. The bones in a baby's head are not fused, so the baby's skull can deform during birth. The mother's pelvis changes shape because of the hormone relaxin released during pregnancy. The baby's head rotates as it pushes through the birth canal to help with clearance. Even with all that, childbirth is still an extremely painful exercise for the mother because of the baby's head size.

But with 25% of babies being born by C-section, there really isn't any constraint on head size any more. Evolution has total freedom. Does the C-section allow humans as a species to make an evolutionary leap and double our brain size? Once we've made the leap, we become a species completely tied to technology -- it is impossible for a child to be born without a C-section. We are dependent on technology for the survival of the species.

What other ways might evolution exploit to opportunities that C-sections provide?