The recent increase in temperature reminds us that summer is here. Most of us cannot stand the heat and start sweating immediately and stay in our air conditioned room all the time. What many people don’t realize is that sweating is a natural phenomenon that our body has developed over time to help us cool down. Humans possess a high density of sweat glands embedded in their skin–10 times the density of chimpanzees and macaques. Some researchers at Penn Medicine have discovered how this hyper-cooling trait evolved in the human genome. There was a study published in the Proceedings of the National Academy of Sciences where researchers showed that the higher density of sweat glands in humans is largely due to increased changes in a regulatory region of DNA called an ‘enhancer’ region. This region regulates the sweat gland-building gene, explaining why humans are the sweatiest of the Great Apes.
Most scientists assume that humans' high density of sweat glands, called eccrine glands, are due to an ancient evolutionary adaptation. This adaptation, along with the loss of fur in early human beings, promoted cooling through sweat evaporation. It is thought to have made it easier for them to hunt, run and survive in the African savannahs, a hot and relatively treeless region which is a different habitat than the jungles occupied by other ape species. Yana Kamberov found in a study that a gene called Engrailed 1, EN1 in humans, helps in determining the density of eccrine glands in mice. EN1 encodes an arranging factor protein that, among other functions, works during development to induce immature skin cells to form eccrine glands.
This property led Kamberov and her colleagues to theorize that evolutionary changes that increased the production of EN1 in the skin might have possibly caused humans to build more sweat glands. Kamberov and her team’s work suggests that the human "high-sweat" trait evolved partly through repeated mutations to just one regulatory region, hECE18. This means that this single regulatory element could have repeatedly contributed to our tremendous cooling capacity as compared to those of our ape counterparts. This is the history of how we have evolved to get ‘cooler’.
Differentiation of the process of sweat glands produced between a chimp,human and a rodent.
留言