How Do Fireflies Glow? Mystery Solved After 60 Years
Scientists have sussed out the chemical secret of these bright summertime beetles—and it may someday improve human health, a new study says.
For around 60 years, scientists have known what basic ingredients go into the box—things like oxygen, calcium, magnesium, and a naturally occurring chemical called luciferin.
And they've known what comes out of the box—photons, or light, in the form of the yellow, green, orange, and even blue flickers you see dancing across your backyard on summer nights.
But until recently, the actual chemical reactions that produce the firefly's light have been shrouded in mystery. And scientists like Bruce Branchini at Connecticut College love a good mystery. (Also see "Fireflies Are 'Cannibals'—And More Surprising Facts About the Summertime Insect.")
The discovery, published recently in the Journal of the American Chemical Society, provides the most detailed picture yet of the chemistry involved in firefly bioluminescence. (See other pictures of glowing animals.)
Specifically, two of the ingredients mentioned above—oxygen and luciferin—aren't likely to react to each other in the way they would need to in order to produce light.
Understanding why this is gets complicated fast, but a simple explanation is that apples tend to only create chemical reactions with apples, while oranges tend to only create chemical reactions with oranges. In other words, oxygen and luciferin are like apples and oranges.
This extra electron gives the oxygen properties of both a metaphorical apple and a metaphorical orange. This means that the molecule would, in fact, be able to cause a chemical reaction with the luciferin like scientists have suspected.
"To me, chemically, this is the only way it makes sense," says Stephen Miller, a chemical biologist at the University of Massachusetts Medical School who also studies luciferin and its potential uses for human health.
For instance, earlier this year, Miller was part of a team that used luciferin to detect specific enzymes in the brains of living rats, which could someday offer doctors another window into the human brain.
By Jason Bittel, National Geographic