The article looks at research by microbial ecologist John Priscu on the microorganisms found in the melting ice sheets of the glaciers of Antarctica, finding the presence of living bacteria in ice from 420,000 years ago that retain the ability for growth and cell division. The species identified were similar to common existing bacteria. Researchers are concerned that although these bacteria do not seem to be dangerous to mammals, they could evolve to compete with modern-day bacteria.