Fascinating! I’m going to link this in to the main article. I was aware of the whole “humans adapted to long distance running” thing, and how sweat is optimized for that, but I hadn’t considered the related implications for brain cooling.
Human brains are about 3x larger, and thus require/output 3x more energy and surface power density, than our similar-ish sized primate relative with similar-ish sized skulls. Brain tissue also has a 10x higher power density than the rest of the body. This does suggest the need for significant evolutionary optimization towards cooling.
There is a minor literature on the evolution of brain cooling as potentially “blocked in early primates and then unblocked sorta-by-accident which allowed selection for brain size in hominids as a happy side effect”. I’m unsure whether the hypothesis is true or not, but people have thought about it with some care and I’ve not yet heard of anyone figuring out a clean kill shot for the idea.
Fascinating! I’m going to link this in to the main article. I was aware of the whole “humans adapted to long distance running” thing, and how sweat is optimized for that, but I hadn’t considered the related implications for brain cooling.
Human brains are about 3x larger, and thus require/output 3x more energy and surface power density, than our similar-ish sized primate relative with similar-ish sized skulls. Brain tissue also has a 10x higher power density than the rest of the body. This does suggest the need for significant evolutionary optimization towards cooling.
There is a minor literature on the evolution of brain cooling as potentially “blocked in early primates and then unblocked sorta-by-accident which allowed selection for brain size in hominids as a happy side effect”. I’m unsure whether the hypothesis is true or not, but people have thought about it with some care and I’ve not yet heard of anyone figuring out a clean kill shot for the idea.