New Insights into the Plague’s History

A recent study delves into one of humanity’s most notorious pathogens: the plague.

Mary Louise Kelly, the host, introduces the topic by linking the current Ebola outbreak to how diseases can transition from animals to humans and circulate through populations. This new research on the plague, as reported by Nate Rott, is said to rewrite much of what we know about this historical illness.

According to Rott, the study begins with an intriguing discovery made by archaeologists near Lake Baikal in southern Siberia, home to the oldest and deepest freshwater body. The area is lined with burial sites of prehistoric hunter-gatherers who returned repeatedly to inter their dead. Yet, one particular site didn’t align with the findings from others.

Ruairidh Macleod, a post-doctoral researcher at Oxford and the study’s lead author, pointed out that this site exhibited a starkly high mortality rate, particularly among children and young adolescents.

MacLeod elaborated that in most cemetery sites, mortality tends to peak in the mid-20s when individuals are engaging in riskier behavior, indicating a more typical distribution. However, they found no signs of violence at this site.

MacLeod noted that the timing of the deaths was extraordinarily compact, which is quite unusual for the region.

Focusing on ancient DNA, MacLeod sought to uncover potential clues in the genomic data from the bones. By analyzing tiny samples from over 5,000-year-old teeth, he managed to reconstruct their DNA.

In a surprising twist, MacLeod and his team matched this data against a broad database of pathogens and discovered that many of these ancient individuals carried plague DNA.

The plague is caused by the bacterium Yersinia pestis, widely recognized for its catastrophic impact in 14th-century Europe during the Black Death and earlier during the Roman Empire. However, the strain identified in this study was unique; it lacked a specific gene that made later plagues particularly deadly but contained a super antigen not found in later variations.

MacLeod explained that super antigens provoke massive immune responses, which can lead to cytokine storms, toxic shock syndrome, and ultimately, death.

There remain numerous questions about the origins and evolution of the plague. The researchers suggest that the disease likely initially transmitted from animals like marmots to humans. Taylor Hermes, an anthropologist from the University of Arkansas who was not associated with the study, is investigating how the plague might have transitioned from wild animals to humans and even livestock. He believes this recent finding underscores an important point.

Hermes remarked that it isn’t only large agricultural societies acting as breeding grounds for diseases.

This perspective challenges a commonly held belief in discussions about infectious diseases. Hermes added that this study hints at the fact that various groups, regardless of size, can disrupt environments in ways that enable diseases to emerge, with consequences that resonate even today.

Rott concludes that this is a crucial insight to keep in mind as we navigate a globalized world.