News Snapshot:
Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. CNN — In the largest DNA analysis of its kind, scientists have found evidence to suggest that historic plague pandemics, such as the Black Death, were not caused by newly evolved strains of bacteria but ones that could have emerged up to centuries before their outbreaks. The plague-causing bacterium Yersinia pestis is dated to have first emerged in humans about 5,000 years ago. Through animals and trade routes, Y. pestis spread globally over time on multiple occasions, according to a...
