Curly hair kept early humans cool

[sybylla]

6. Entirely possible.

On the other hand, evolution doesn't happen outside of environmental conditions.

Having studied mesoamerican cultures, I've not seen any studies showing that it is anything but tropical forest - rain forest or not - to the point that the forest quickly took over and covered all the beautiful classical Mayan pyramids. All that cover plus lush vegetation and fibers to produce clothing and headwear would negate curly hair evolution.

I don't know enough about the environment in which curly hair developed to comment further nor how many years such an evolution would take.

I do find the facts around the insulating properties of curly hair pretty logical in a way that makes me wonder why it took until the 21st century to even study it and prove it. I mean, we already knew this about the tight curls of sheep being both a cooling (in hot weather) and a warming (in cold weather) mechanism to moderate body temp.