Our ancient enemy: scientists discover oldest-known plague outbreak (opens original article in a new tab)

Scientists found the oldest evidence of the plague, dating back 5,500 years, with outbreaks likely spreading from marmots to humans and between people.

• Scientists discovered the oldest-known plague outbreak dating back 5,500 years.
• The plague likely spread from marmots to humans through raw organs or infected hides.
• The study analyzed DNA from 18 ancient hunter-gatherers near Siberia's Lake Baikal.