Animal echolocation in the external ear. There are two hypotheses about the evolution of echolocation in bats. The first suggests that laryngeal echolocation evolved twice in Chiroptera, once in the Yangochiroptera and once in the horseshoe bats (Rhinolophidae). The second proposes that laryngeal echolocation had a single origin in Chiroptera, was subsequently lost in the family Pteropodidae (all megabats), and later evolved as a system of tongue-clicking in the genus "Rousettus". Individual bat species echolocate within specific frequency ranges that suit their environment and prey types. This has sometimes been used by researchers to identify bats flying in an area simply by
Robert Galambos generate and hear sounds an octave higher than can be heard by humans and other animals. Experiments they conducted used methods developed by Hallowell Davis to monitor the brains of bats and their hearing responses as they navigated their way past wires suspended from a laboratory ceiling. They showed how bats used echolocation to accurately avoid obstacles, which they were unable to do if their mouths or ears were kept shut. Griffin coined the term "echolocation" in 1944 to describe the phenomenon, which many physiologists of the day could not believe was possible. Using electrodes implanted in the brains of