37,000 Years of Disease

With ancient DNA, scientists have mapped 37,000 years of disease across Europe and Asia.

More than 200 modern diseases are zoonoses—that is, they can spread to humans from other animals. Both rampant and widespread, zoonoses are often at the center of contemporary outbreaks, epidemics, and research. Six out of ten known infectious diseases are zoonotic, and three out of four new or emerging diseases that affect humans come from animals.

For a long time, scientists have speculated that these diseases began afflicting societies around the time animals were domesticated. But they’ve never had genetic evidence or pinned down a specific timeline—until now.

A team of scientists have traced the genetic history of 214 diseases across Europe and Asia over the last 37,000 years. Their findings indicate that the rise of animal husbandry forever shaped humanity’s relationship with disease. However, the timing defied their expectations.

The researchers found that zoonotic pathogens emerged roughly 6,500 years ago and spiked 5,000 years ago. That was surprising because it was several thousand years after humans began domesticating animals in Mesopotamia and southeast Asia. But the evidence says zoonoses initially became prevalent in Asia and Russia as communities transitioned from hunter-gatherer lifestyles to nomadic livestock herding or farming.

Having already tamed horses, communities began to travel in wagons pulled by oxen, which allowed them to voyage farther and exchange goods, ideas, and diseases with other communities. Though some pathogens may have moved from animals to humans even earlier, research suggests these changes made the spread more prevalent.

A vast analysis of DNA from ancient human remains made this study possible. The researchers extracted remnants of microbial genetic material from the teeth and bones of 1,313 human skeletons and identified 5,486 DNA sequences from bacteria, parasites, and viruses. Many remains were found in the same graves, indicating that a single contagion killed multiple people.

The study builds on existing evidence that mutations in these pathogens strengthened the immune systems of the nomads who were the first to get sick, while farmers and hunter-gatherers succumbed to the new diseases. But another study suggested that these nomads’ evolving immune systems might have also made them susceptible to chronic illnesses, like multiple sclerosis.

Understanding the ways pathogens affected humans long ago could help improve modern treatments and methods for preventing disease.

Successful mutations of the past are likely to reappear. So knowledge is important for future vaccines. Knowledge allows us to test whether current vaccines provide sufficient coverage or new ones need to be developed due to mutations.

Scientists analyzed one sample dating to 5,500 years ago, which contained the world’s oldest known genetic trace of yersinia pestis, which caused the plague that killed between 30 and 50 percent of Europe’s population during the Middle Ages. It’s just one example of how zoonoses have had a massive influence on human history and culture.

Other diseases identified in the human remains include malaria (4,200 years old), leprosy (1,400 years old), Hepatitis B (9,800 years old), and diphtheria (11,100 years old).

The work has some limitations. The genes of many viruses are encoded in RNA, which was not studied. The research might have missed some pathogens that were present at low levels. The history revealed is limited to the Eurasian sites where the skeletons were found.

I look forward to the day when my immune system figures out how to avoid covid-19.

 

https://www.msn.com/en-us/health/other/with-ancient-dna-scientists-have-mapped-37-000-years-of-disease-across-europe-and-asia/ar-AA1Jag8R?ocid=hpmsn&cvid=79a5e33a5ea742c0a9a5e8ffd7787b1a&ei=29