One of the 5,000-year-old pots where reseaerchers found animal proteins (left). An artist reconstructed what the cauldron would look like toady (right).iScience/Wilkin et al. Researchers found a unique way to identify what people ate thousands of years ago. They analyzed proteins from 5,000-year-old copper-alloy cauldrons to see what animals people cooked. Blood, milk, and muscle from cattle, goats, or sheep were all preserved in the pots. About 5,000 years ago, ancient cooks were creating feasts out of cattle, deer, and milk from sheep or goats.They could've been eating their meat and dairy separately or mixing it all together.