The arrival of humans in America led to the extinction of almost 130 faunal species. A British Broadcasting Corporation report indicates that early immigrants brought with them deadly viruses that led to a host of diseases in the animal population of the continent. "They brought along-with them parasites, which they knew nothing about,' says Ross MacPhee, a paleontologist. MacPhee hopes that deoxyribonucleic acid (DNA) analysis of recently excavated 26,000-year-old woolly mammoth specimens, will support his theory.