Bos began researching plague as a member of the McMaster University Ancient DNA Centre. Bos and Verena Schuenemann of the University of Tübingen, led a research project, co-sponsored by the McMaster Ancient DNA Centre and the University of Tübingen, to sequence the DNA of the Black Death pathogen, Yersinia pestis, recovered from plague victims at a medieval London burial site. The archaeological excavation of the plague cemetery was managed by the Museum of London Archaeology.[2][3]
After examining bacterial samples from 46 teeth and 53 bones, the research team was able to establish that Yersinia pestis was the cause of Black Death, which killed over 30 million people in 14th century Europe.[4] The team also determined that the ancient pathogen is the predecessor of all modern variants of plague and the medieval bacteria hasn't changed much since the Middle Ages. The team's findings were published in the journal Nature in December, 2011.[4][5]
Bos led a recent study, which discovered that an ancient strain of tuberculosis (TB) migrated to the New World by infected sea lions and seals. The research team from the University of Tübingen, examined thousands of skeletons for TB, and were able to extract (TB) DNA from three skeletons uncovered in southern Peru. It was determined that the remains were buried 1,000 years ago, before the arrival of Europeans to the New World. The researchers also established that the ancient TB was different from modern tuberculosis bacterium.[6][7]
The study results, which were published in the journal Nature in October, 2014, proposed that a new strain of TB, dissimilar to TB strains that were in existence throughout the world 1,000 years ago, had migrated to South America.[6] Researchers came to the conclusion that the ancient Peruvian form of TB was almost identical to TB strains identified in pinnipeds–a group that includes seals, sea lions and walruses. The study's results indicate that TB emerged in Africa approximately 6,000 years ago and the TB bacterium moved from land animals to a sea lion or seal, which then traveled across the ocean to the South America. The sea animals, at some point, probably infected people living in coastal Peru and northern Chile.[7]