system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why don’t we have fat and muscle surrounding our brains as an added protective layer over our skulls?
gpt
Heat retention. The brain uses a large portion of our energy and the temperature range from  normal to heat stroke is all of 3 degrees  C. Also because of all of the blood vessels in the brain, a lot of the body's heat is pumped through your head.

Just being hot makes you think slower and make more mistakes.