In Part 1 of this post, we discussed two explanations for difficult childbirth and helpless babies: the Fall and the obstetrical dilemma (OD) hypothesis. Both have their weaknesses. Let’s consider another evolutionary-minded explanation, apart from the OD. For humans, the birth process begins at the same time that pregnancy reaches a critical metabolic threshold. This suggests there is a connection between the two. As a fetus develops and …

Anthropologists often use an idea called the "obstetrical dilemma" to explain why humans have helpless infants, but there is mounting evidence that this explanation is insufficient.