Why some mushrooms glow in the dark

A team of scientists recently created some fake, glowing mushrooms and scattered them in a Brazilian forest in hopes of solving an ancient mystery: Why do some fungi emit light? The question goes back all the way to Aristotle, who is the first person known to have wondered about this, according to Jay Dunlap, a geneticist and molecular biologist at the Geisel School of Medicine at Dartmouth College in Hanover, N.H. He says over the years people have thrown out various explanations for the light — everything from "it's a useless byproduct of metabolism" to "it attracts insects."