As the novel coronavirus pandemic reshapes lives and entire economies, historians tell us this is not the first time. The earliest written records of tiny infectious organisms overhauling human societies stretch back as far as the Plague of Justinian in A.D. 541, which is thought to have killed up to 50 million people, or even the earlier Antonine Plague in A.D. 165, which left 5 million dead, a substantial portion of the world then.

Now, paleogenomics — a nascent field that studies DNA in remnants of ancient teeth — is rewriting the first chapter of humanity’s entanglement with disease to thousands of years older than originally thought. The growing evidence suggests that these first epidemics forced societies to make epoch-defining transformations.

“In the case of covid-19 [the disease caused by the coronavirus], we see similar processes, but we are watching it unfold in real time,” said Anne Stone, regents professor in the School of Human Evolution and Social Change at Arizona State University, whose focus is anthropological genetics. She also has studied evidence of tuberculosis in ancient DNA.

Hannah Jewell looks back at plague and yellow fever outbreaks in Europe and New Orleans, which revealed stark divides between the rich and poor. (The Washington Post)

Paleogenomics, which adapts high-end medical tools similar to some now being used to track the coronavirus, has amounted to a “revolution” in understanding disease history, says Maria Spyrou, a microbiologist at the Max Planck Institute in Germany.

“This is one of the things that we can now start saying,” said Spyrou, adding that where historical records are lacking, DNA evidence offers the possibility of filling in gaps, sometimes in surprising ways.

“One of them is plague,” Spyrou said. “Until 2015, we thought that plague was maybe a 3,000-year-old disease.”

Scientists and archaeologists now believe, however, that the plague bacteria, which caused the medieval Black Death that killed up to half of Europe’s population, infected humans roughly 5,000 years ago in the Stone Age. The bacteria, after it had entered the bloodstream and likely killed the host, circulated into the pulp chamber of teeth, which kept its DNA insulated from millennia of environmental wear and tear. In the past decade, scientists have been able to extract and analyze that DNA.