Goosebumps are a peculiar reaction of our bodies that until now had not been fully understood by science. When we feel cold, our skin stands out with tiny bulbs and the hair in that area stands out prominently. Theories suggested that it might be a holdover from our primitive past, when we were much hairier: such a creepy reaction would have helped us warm up.

A new Harvard study has unraveled the biological reason behind the phenomenon: it is the How our body stimulates stem cells to drive hair growth. To find out why it persists today, after centuries of evolution, the team investigated what is happening at the cellular level under our skin.

In tests on mice, the researchers found a potential purpose: those cells that cause goosebumps also play an essential role in regulating stem cells that regenerate hair and hair follicle. This effect increased when the cold temperatures were prolonged. In this way, goosebumps are a short-term solution, while the body tries to stimulate hair growth to keep us warmer in the long term.

“This particular reaction is useful for coupling tissue regeneration with changes in the outside world, such as temperature,” says Yulia Shwartz, co-author of the study, as reported by New Atlas. The scientist explains that the answer has two layers: on the one hand, goosebumps provide short-term relief and on the other, when the cold lasts, it becomes a pleasant mechanism for stem cells to know that it may be time to regenerate the new layer of hair.

The general cellular mechanism behind goosebumps has been known for a long time. When it is cold, the sympathetic nerve contracts a small muscle that connects to the bottom of a hair follicle. This pulls on it, making the hair stand on end. It also causes the skin around the hair to stretch inward, which is what creates the irregular texture responsible for baptizing it with this name.

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The novelty of this study resides in a new part of the equation: after examining the skin with the help of an electron microscope, they discovered that the sympathetic nerve also has a direct connection with the stem cells of the hair follicle, enveloping them. Therefore, when the nerve activates, so do the stem cells responsible for the growth of new hair.

This is explained by Ya-Chieh Hsu, co-author of the study, reporting that they could see at the ultrastructure level how the nerve and stem cells interact. “Neurons tend to regulate excitable cells, like other neurons or muscles with synapses. But we were surprised to find that they form synapse-like structures with an epithelial stem cell, which is not a very typical target for neurons, “he says.

The next step for researchers will be to continue delving into how the external environment affects stem cells in the skin. The research is available in the journal Cell.

Source | New Atlas

This article was published in TICbeat by Andrea Núñez-Torrón Stock.