Rattlesnakes silently shook their tails before evolving rattles

Shake, rattle and strike. It is possibly one of the most terrifying sounds in the animal kingdom, but how the rattlesnake evolved its chilling warning signal is a mystery. Now a study suggests the rattle evolved long after the tail-shaking behaviour.

The evolution of the rattle has baffled scientists because, unlike other complex physical traits like eyes or feathers, it has no obvious precursor or intermediate stage.

“There is no half-rattle,” says David Pfennig at the University of North Carolina at Chapel Hill. Read more in New Scientist.