They took the language of the Hittites, a people that existed during the time the war may have been fought, and modern Greek, and traced the changes in the words from Hittite to Homeric to modern. It is precisely how they measure the genetic history of humans, going back and seeing how and when genes alter over time.
For example, they looked at cognates, words derived from ancestral words. There is "water" in English, "wasser" in German, "vatten" in Swedish, all cognates emanating from "wator" in proto-German. However, the Old English "hund" later became "hound" but eventually was replaced by "dog," not a cognate.
"I'm an evolutionary theorist," Pagel said. "I study language because it's such a remarkable culturally transmitted replicator. It replicates with a fidelity that's just astonishing."
By documenting the regularity of the linguistic mutations, Pagel and the others have given a timeline to the story of Helen and the men who died for her -- genetics meets the classics.