I've still been thinking about the "What aspect of the human body could you improve?" question in relation to the design of our brains.

I was thinking about how evolutionarily rapidly the primate neocortex has expanded, leading to larger, more dome-shaped skulls in modern humans. A limiting factor in increased expansion is the size of the female birth canal.

However, the simple medical procedure of the c-section basically eliminates this constraint. From just some informal poking around on the internet, it sounds like about a quarter of all pregnancies in the US are delivered via c-section.

There is an actual medical term for the baby's head and/or body being too big for the woman's pelvis; it's called Cephalopelvic Disproportion. However, it's supposedly not all that common. There are a number of other reasons women have c-sections, including bad advice from doctors.

Anyway, I was wondering if anybody had been tracking modern cranial volumes in societies where c-sections have become much more prevalent, and whether any statistical increase has been noted. I don't know...it seems that measures of cranial volume have been controversial, in terms of justifying racism on that basis. And many people argue over the strict correlation between cranial volume and intelligence (though there is no doubt there is a correlation).

This may be speculative crankpottery, but if anybody sees anything out there about the increase or stability of modern skull sizes, give me a holler.