We all know what goosebumps are, but why have we evolved to hang on to this seemingly pointless physical reaction to the cold? New research suggests an answer: regulating stem cells that control hair follicles and hair growth.
In a detailed analysis of mice, scientists found that the specific muscles that contract when goosebumps appear are connected to the sympathetic nervous system. When low temperatures are sensed, these muscles bridge the gap between sympathetic nerves and hair follicles.
In the short term, it causes hair to stand up and goosebumps to appear; in the long term, it appears to promote hair growth. The researchers say this is an important link between stem cells – which the body can use to create other kinds of cells – and external stimuli.
Above: Hair follicle, sympathetic nerve (green), and muscle (magenta) under the microscope.
“The skin is a fascinating system,” says biologist Ya-Chieh Hsu from Harvard University. “It has multiple stem cells surrounded by diverse cell types, and is located at the interface between our body and the outside world. Therefore, its stem cells could potentially respond to a diverse array of stimuli – from the niche, the whole body, or even the outside environment.
“In this study, we identify an interesting dual-component niche that not only regulates the stem cells under steady state, but also modulates stem cell behaviours