Brain size

V

Varda

The Bug Lady
Valued Senior Member
Forgive me if this is complete bullshit

i heard from someone that, in evolutionary therms, the size of the brains of foetii grew as the female sacral bones became wider, and that the female hips are as wide as they can be without altering the ability to walk, which limited the evolution of the brain

if that is so, is it possible that the advent of c-section surgeries might allow for more brain growth
 
Varda said:
Forgive me if this is complete bullshit

i heard from someone that, in evolutionary therms, the size of the brains of foetii grew as the female sacral bones became wider, and that the female hips are as wide as they can be without altering the ability to walk, which limited the evolution of the brain

if that is so, is it possible that the advent of c-section surgeries might allow for more brain growth
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That was once thought to be true (a very long time ago) but has been discarded.

As to the final question, no. There's no evidence to support that cranial size at birth has any relationship to size at adulthood.

It's also worth noting that brain/cranial size was once thought to be an indicator of intelligence in humans. That too has been throughly debunked and discarded as archaic thinking.
 
We humans go through a premature birth compared to chimps. The size of our brain is somewhat of a problem in all this. The timing of our birth is a compromise between the width of the pelvic, the size of the head (which relates to the size of the brain) and the developmental state of our lungs. They are just about functional when a human baby is born.

To manage this compromise we have become a primary example of heterochrony (if this is still an acceptable idea). Heterochrony is basically the speeding up or slowing down of developmental processes.

Our brains have a growth spurt just before birth just as chimps but unlike chimps ours keep continuing to develop way passed birth. You might look at it as maintaining the growth rate of neural cells typical of a fetus in a new born. The ratio between brain weight and body weight is quite similar between chimp and human at birth but this continuation of brain growth in humans quickly puts us ahead.

All this growth cannot take place inside the womb. Our head would be too big. So the human newborn resembles a primate fetus. Hardly fully developed, and completely dependent on its parents. More so than any other primate.
 
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