Scientists uncover new hormone in unusual discovery

A 3d illustration showing a woman's side profile, with her brain and spine shown as if through x ray.

Scientists just discovered a hormone that may solve a long-standing biological mystery. 

It's difficult to prove you've identified a new hormone — a chemical signal that directs behavior in distant cells, often by traveling through the bloodstream. To be sure, you need to confirm where it's made, which tissues it affects and that it can be found in the bloodstream, senior study author Holly Ingraham, a professor and vice-chair of cellular and molecular pharmacology at the University of California, San Francisco, told Live Science.