Despite the common saying, bats aren’t actually blind—but about 85% of bat species can hunt in the dark by tracking the echoes of their own voices, an ability called laryngeal echolocation. (See the article by Whit Au and Jim Simmons, Physics Today, September 2007, page 40.) The remaining 15%, a group called the Old World fruit bats (for example, the lesser short-nosed fruit bat shown here), rely on plain old eyesight. This finding has led to a fierce debate among evolutionary biologists: Did bats descend from a single ancestor capable of laryngeal echolocation, with fruit bats losing the ability somewhere along the way? Or did laryngeal echolocation evolve independently in different branches of the bat family tree?
A team of researchers led by Shuyi Zhang at Shenyang Agricultural University may have uncovered new clues to this evolutionary mystery by studying the fetal development of bats’ ears. Many...
