PUERTO RICO: Early inhabitants of Puerto Rico ate a lot of clams, but they didn’t boil the mollusks in soup or enjoy them raw on the half shell, as is popular today. Instead, they preferred their clams barbecued. Isotope analysis of 2,700-year-old fossilized shells from a pre-Arawak site in Cabo Rojo determined that the shells had been heated up to nearly 400°F, far above the boiling point. This suggests the bivalves had been roasted on a hot surface over a roaring fire.