The problem: Scientists want to study our circadian rhythms, our bodies' internal clocks, and they can do so on the genetic level by examining how gene expression changes throughout the day. But ordinarily that would require sampling a person's blood or skin multiple times a day, an ordeal few of us would want to endure. The solution: hair. Makoto Akashi's team reports today in the Proceedings of the National Academy of Sciences that hairs, be they from the beard or head, contain the telltale signature of RNA activity that shows when we humans are at our peak activity level for the day.
At the base of every strand of hair is a follicle of living cells, which clings to the hair when plucked. By tweezing an average of 10 head hairs per person (five for thick-haired folks and as many as 20 for those with thin locks), the researchers were ...
