We lost our fur at least 3 million years ago

Some anthropologists suggest that we lost our hair with the appearance of H. Erectus and its tropical climate adaptations. Arguing that dark skin replaced the protective function of fur, another group suggests that fur loss occurred 1.2 million years ago, since the dark skin mutations date to then (Genetic Variation at the MC1R Locus and the Time since Loss of Human Body Hair). Others, taking an archaeological approach, note that borers and other stitching equipment show up only with modern humans, and argue that modern humans are the only hairless species.

Dates so late are problematic because hominins had been exploiting the savanna long before this. The “radiator” hypothesis has been crucial in understanding that major drainage systems within the skull are set in place to keep the brain cool and date to very far back, probably with the ancestors of H. Habilis (Falk’s radiator hypothesis | Behavioral and Brain Sciences | Cambridge Core). Thus, cooling systems would precede brain expansion, and not the other way around. This would indicate a date before 2.2 mya.

Hair does not preserve in the fossil record, but we can say a great deal from other facets of our body like lice. The lineage of lice is immortal since it passes to other members of one’s family. Thus we have a pristine record of where the lice were clinging and their relation to other parts of the body. With most animals, one form of lice dominates the whole body, because the fur stretches across the whole body. Indeed, with all great apes, there is…