Languages change so fast, the linguists point out, that their genealogies can be traced back only a few thousand years at best before the signal dissolves completely into noise: witness how hard Chaucer is to read just 600 years later.

But the linguists' problem has recently attracted a new group of researchers who are more hopeful of success. They are biologists who have developed sophisticated mathematical tools for drawing up family trees of genes and species. Because the same problems crop up in both gene trees and language trees, the biologists are confident that their tools will work with languages, too