Eccrine sweat glands: A new sensitivity & mobility.

Round about 2,000,000 years ago our ancestors were moving across the landscape, out of the forests, running long distances, collecting tool material, exploiting the midday period when quadripeds soaked too much heat to be active. This meant we needed to dissipate heat ourselves. What better way than a network of two to four million eccrine sweat cells spread across the surface of our skin? By that time most of our sweat glands were on our palms and soles. They originally provided moisture for better grip when fleeing or fighting and were emotionally activated. Since we started to stand upright, exploit the midday times when most quadripeds rested our species evolved any sweat glands that activate based on heat. Now most sweat glands are used solely to dissipate heat. 

I'm amazed by simple seeming innovations to our genotype that end up providing a real advantage to us as individuals. I'm also amazed at how memotypes sometimes work to overcome innovations as in the development of antiperspirants and deodorants.