The deadliest and most devastating opponents our species has faced have never been across a battlefield. They’ve been on our skin and in our blood and bones.
Viruses and bacteria have killed or debilitated millions during the course of human history — and well before. Researchers have unraveled the story of a few, most notably the bacterium Yersinia pestis, which causes plague. But findings about the origins and evolution of other scourges, including leprosy, hepatitis B and syphilis, have been elusive or contradictory.
Now, two key advances — a surge in ancient DNA samples and powerful computer programs to process the data — are allowing scientists to study disease-causing bacteria and viruses like never before.
“There were very few ancient human virus samples even six months ago,” says Terry Jones, a computational biologist at the University of Cambridge. “In terms of being ‘ancient,’ 300 years was considered old, and that was only two or three samples. Now we’re finding viruses up to 7,000 years old. … We’ve gone from zero to this almost out of the blue.”
Jones and fellow Cambridge computational biologist Barbara Mühlemann were key members of a team that published the oldest known genome of the hepatitis B virus (HBV) in Nature in May. The roughly 4,500-year-old sample was one of a dozen ancient HBV genomes found as the researchers sifted through one of the largest databases of ancient human DNA ever assembled.
