Andrew William Best

ANDREW BEST, then a graduate student at University of Massachusetts, Amherst, Massachusetts, was awarded a grant in October 2019 to aid research on ‘Diversity and Evolution of Human Eccrine Sweat Gland Density,’ supervised by Dr. Jason Kamilar. Sweating via eccrine glands is a key adaptation in the human genus but little is known about its origins or the patterning of sweat gland diversity in contemporary humans. This project measured functional eccrine gland density (FED)’the density of eccrine glands responding to pharmacological stimulus’in 78 volunteers of varying childhood climates and geographic ancestries. An additional group of nine endurance athletes were recruited to test the relationship between FED and heat dissipation capacity. Results indicated no effects of childhood climate variables (average annual temperature and humidity) on adult FED, nor did geographic ancestry explain diversity in FED. FED was not associated with heat dissipation capacity. Taken together these results suggest that the range of contemporary variation in FED, roughly 62-133 glands/cm2, has little physiological consequence, perhaps because skin coverage in sweat can be maintained even at the low end of this range, and sweat output per gland can be adjusted to match sweating capacity to demand. Further research is needed to determine if low FED is associated with impaired evaporative heat dissipation while dehydrated.