Tattletale Termite

MOST HOMEOWNERS WOULD READILY AGREE THAT the only good termite is a dead termite, but the one unearthed on a dig in the Dominican Republic was better than most. The insect, trapped between 25 million and 30 million years ago in a blob of tree sap that hardened into amber, has yielded genetic material that is the oldest ever studied, by at least 8 million years. It has also resolved a long-simmering dispute over the family tree of cockroaches.

In the past, the tiny scraps of ancient DNA that can be found in mummified tissue would have been far too small to study. But a relatively new genetic- engineering method called polymerase chain reaction (PCR) can clone enough copies for scientists to examine the DNA in detail. They can then compare ancient genes to modern ones. That gives researchers another perspective on how evolution has changed a given species, beyond what can be learned by the traditional method of studying changes in body structure.

Structural analysis had left researchers with a puzzle about the relationship between termites and roaches: Did the former evolve from the latter, or did both come from a single, common ancestor species? There were arguments for both options -- until a team at the American Museum of Natural History applied PCR to the genetic material of the amber-clad termite. DNA doesn't lie: the cockroach is not the termite's parent after all, but only its sibling. Which says nothing about how to get rid of either.