Ice ages are, like the name say, ages. No problem if the Earth heating would take ages. We would have time to evolve 60° body temperature or something... Also,

Ice ages are, like the name say, ages. No problem if the Earth heating would take ages. We would have time to evolve 60° body temperature or something... Also, when too cold, kill a sheep, take it's coat. When too hot, what are we (and our animals, food and pets) going to do? Undress our own skin?