The earliest plague victims were found in the Lake Baikal region

Two girls, ten and five years old, and in addition to them, a boy about eleven years old.

The girls were half-sisters. They had a common mother. The boy was not a close relative of either of them. Plague bacteria DNA was found in his remains.

Children lived 5,500 years ago. They are now the earliest known people to have died of the plague.

Departed were hunter-gatherers who lived around Lake Baikal in Siberia.

The researchers analyzed the ancient DNA of a total of 42 deceased who had been buried in four ancient cemeteries in the area.

They found the plague bacterium in the remains of a total of 18 people. Many of the dead were buried with other people, and there were many children among them.

The plague seemed to hit children between the ages of 8 and 11 particularly fatally.

The study was published on Wednesday In the journal Nature.

The plague is historically one of the infectious diseases that have killed the most people.

The most famous plague pandemic is the Black Death that raged in Europe in the 14th century. It killed an estimated 25 million people. The disease was transmitted by fleas that spread with the rats.

Now, the ancient plague bacterium found in graves in the Baikal region probably spread in a different way. It lacked the gene that allows it to catch fleas.

This plague probably passed to humans from marmots living in Siberia. After that, the disease could spread as droplets or aerosols from one person to another.

Earlier researchers have thought that the spread of diseases from animals to humans is likely when different species live closely together in farming and animal husbandry societies.

Hunter-gatherers lived quite loosely and mobilely, and got sick despite that.

The disease did not strike the Lake Baikal region only once, but the epidemic recurred a few decades later.

Research also sheds light on the origin of the plague bacterium. It is possible that the bacterium has its roots in central or northeastern Asia.

However, the origin of the ancient bacteria was not the same as the one that caused the black death Yersinia pestis According to the researchers, it was a unique transformation that developed approximately 5,700 years ago.