Seals of doom

摘要

When a few intrepid humans crossed the Bering land bridge from the Old World to the New, to populate the Americas 12,000 years ago, they left many things behind. Among them were several diseases-including smallpox, malaria and tuberculosis-that remained unknown to their descendants until a larger human influx began to arrive in 1492. Or rather, in the case of tuberculosis, remained almost unknown. For a few pre-Columbian skeletons bear unmistakable signs of the infection, creating a mystery that has puzzled anthropologists for decades.