Anthropology professor Nina Jablonski has revealed how humans may have lost their fur to help reduce this heat load on the brain. She describes how, among other factors, “shedding our body hair was surely a critical step in becoming brainy.” Sweating helps to cool us down, but if the hair is thick, the excretions from our eccrine sweat glands would quickly matt the hair, hampering heat loss. Therefore, a rise in hairlessness would be of an increasing benefit. Sweating also carries heat away more effectively in drier environments, so a humid environment would also hamper heat loss through
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