Rainforest katydids evolved mammal-like ears

Tiny organs below insect’s knees have a structure similar to those in humans

A rainforest katydid doesn’t talk like a mammal, or walk like a mammal, but it does hear with the first mammal-like, three-stage sound-sensing system known outside vertebrates.

LIKE A HUMAN A rainforest katydid from South America has independently evolved its own version of the three-step hearing process previously thought to be unique among vertebrates.