2300 years ago, Aristotle wondered why some mushrooms glow, and now, scientists may finally have an answer. In the journal Current Biology, researchers from the University of São Paulo and from Dartmouth report that light produced by the tropical mushroom Neonothopanus gardneri fluctuates, and is controlled by an internal genetic clock. Dartmouth geneticist Jay Dunlap says that means the light has a purpose. Jay Dunlap (Dartmouth University): So for this regulation to have evolved means there must have been a function to drive the adaptation. HIRSHON: To see what that might be, they observed the mushrooms and also experimented with glowing and non-glowing replicas. The glowing versions attracted far more insects than the others, and the team concluded that the light show is meant to attract light-seeking insects that will pick up fungal spores and carry them to new territory. I’m Bob Hirshon, for AAAS, the science society.