How to Get a Melon Through the Eye of a Needle

Humans have a highly developed set of brains. Our brains are more complex than any other mammal’s. Because our brains are so complex, we have certain abilities that animals do not have to the same extent, such as spoken language, social interaction, and short- and long-term planning. However, this complexity has its drawbacks: our brains are much larger per kilogram of body weight than those of most mammals. This creates a dilemma:

Because we walk upright, we have a smaller opening in our pelvis compared to animals that walk on four legs, like apes. Yet we have very large and complex brains that must pass through this opening at birth. How has Mother Nature solved this problem?

Most animals are born relatively developed. For example, they can often stand shortly after birth. To give our babies the same level of development, they would need to grow in the womb for 12 months instead of 9. However, our brains develop so quickly in the womb that they demand a lot from the placenta, which calcifies by the end of the third trimester. This means the baby must be born. Therefore, babies are essentially born prematurely and need to continue the development that would normally take place in the womb outside of it.

This is the solution to the dilemma: because the brain is much smaller at 9 months than it would be at 12 months, the baby can generally still fit through the mother’s pelvis. So, if you want to get a melon through the eye of a needle, try using a seed—maybe that will work!

In our next article, you will read about what it means that our babies must go through the fourth trimester outside the womb.