Shortly after last year's tsunami devastated the lands on the Indian Ocean, The Times of India ran an article with this headline: "Tsunami May Have Rendered Threatened Tribes Extinct." The article said, "Some beads may have just gone missing from the Emerald Necklace of India."

The metaphor is as colorful as it is well intentioned. But what exactly does it mean? After all, in a catastrophe that cost more than 150,000 lives, why should the survival of a few hundred tribal people have any special claim on our attention?

Human physical variation is correlated; and correlations contain information. Genetic variations show similar correlations.