The sympathetic nervous system was thought to have evolved with jawed vertebrates. But lampreys—jawless, parasitic fish that suck out the blood of their hosts—have a simple one, per recent research.

The sympathetic nervous system, which enables the fight-or-flight response, was thought to be present only in jawed vertebrates. Analysis of a jawless vertebrate suggests that this system might be a ...

The term “sympathetic nervous system overload” sounds daunting, but the root cause is pedestrian: stress. Stress is, of course, something we all experience all the time, but left unchecked, it can ...