Variation in human functional eccrine gland density and its implications for the evolution of human sweating.

We hypothesize that gland-level phenotypic plasticity, rather than changes in eccrine gland density, was sufficient to permit thermal adaptation to novel environments as humans colonized the globe. Future research should measure effects of FED in dehydrated states and the relationship between FED and salt loss, and control for effects of microclimate to rule out phenotypic plasticity effects.