Biologists who study evolution have suggested that the genus Homo was initiated in East Africa more or less 2.5 million years ago. It was during this time that new hunting processes were being innovated. Having higher protein diet easily led to the evolution of larger body and brain sizes. Increasing body size, in correlation with intensified hunting during the day at the equator, gave rise to a higher need to massively expel heat. As a result of this, humans slowly developed the ability to sweat and thus lost body hair to carry on this process. It must also be seen that primates and horses already have armpits that sweat similar to that of humans and thus it cannot be called a new evolution. It can otherwise be termed as a possible preferential selection of perspiration over body hair.

It has however been argued that hominids without fur could not have been able to warm themselves as effectively as at night, nor protect themselves well enough from the sun during the day – neither could have been possible. The probability is such that increased intelligence, coupled with sophisticated hunting processes, helped humans to warm themselves at night with the use of animal skins. To add on to this, assuming that hair loss evolved slowly, dark skin color in all likelihood developed to protect the skin layer during the day. Tanning on exposed layers of the skin is quite common and it is retained for long. Whereas, hyper-pigmentation (as in Africans and Indians) and albinism are later developments. Thus the former hypothesis relating to loss of hair with the evolution of sweat glands is still feasible.