Reframe the question: is coolth a survival value? I spent most of my life in the boreal forests: cooling things off was seldom an issue. Now I am in the land of perpetual heat, and see a lot of resources devoted to creating the chill in an emergency: generators sized to support ac systems, residential structures close to the water )and close to the storm surge) to access sea breezes. Michael Crichton included a high tech tent ac unit in Congo, suggesting that high temp/high humidity interefered with sleep patterns and caused a measurable decrease in human performance.