In 2014, Tuberculosis (TB) surpassed HIV as the leading cause of death from infectious disease. Unlike HIV, TB has long been a scourge of humans; however, exactly how long has been debated. Also controversial has been the presence and relationship of pre-Columbian tuberculosis in the Americas to TB strains in the rest of the World. In this lecture Anne Stone examines the evolutionary history of Mycobacterium tuberculosis, the bacteria that causes TB, focusing on the distribution of TB strains in humans (past and present) in order to understand their relationships, assess patterns of pathogen exchange through time, and investigate how TB adapted to humans and other animals. Her lab group uses new methods of ancient DNA extraction as well as methods to target pathogen DNA to obtain genetic data from ancient samples with characteristic TB bone lesions. To date, they have sequenced the M. tuberculosis genome from three ancient Peruvians dating to ~1000 years ago. Their analyses indicate that this bacteria likely “jumped” from animals and became a human pathogen within the last 6,000 years. In addition, the results show that ancient Peruvian TB strains are distinct from any known human-adapted TB strains and are most closely related to strains adapted to sea mammals. Sea mammals, specifically Southern Hemisphere seals and sea lions, acquired strains from other animals in Africa and then within the last 2000 years brought these TB strains to South America.