Not only does new research shed light on how young of a disease tuberculosis is, but it also shows that seals and sea lions carried the disease to the Americas.
The origins of tuberculosis have been a mystery. However, this new research suggests that it wasn't humans that carried the disease from Africa to South America, but creatures known as pinnipeds, such as seals and sea lions. The South American natives contracted it and then spread it to the Europeans after they arrived there.
According to the CDC, tuberculosis is an infectious disease that kills around 2 million people every year. It's caused by a specific bacteria called Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs, but can attack other parts of the body, such as the brain and kidneys.
Tuberculosis, or TB, is a highly infectious airborne disease and spreads when someone comes into contact with an infected person who coughs, sneezes or speaks.
The most widely held theory about how TB originally spread from Africa to the Americas involves the Europeans bringing it with them during their age of exploration.
"The age of exploration is a time when people are moving really long distances around the world and coming into contact with others. It's a time when a lot of disease spread," says researcher Anne Stone.
However, after studying genomes from 1,000-year-old Peruvian remains, researchers discovered that one strain existed in South America before the Europeans ever set foot there.
So how did it get there?
Previously, scientists estimated TB at about 70,000 years old. However, these researchers tested and analyzed DNA on both modern strains and the Peruvian strain and discovered that it is only about 6,000 years old.
This finding led to a puzzle. TB was originally thought to have come to the Americas via the land bridge that once existed between North America and Asia. However, if TB is only 6,000 years old, that land bridge was gone by the time TB arrived.
To solve the mystery, researchers studied the DNA of the types of strains of TB that infect animals. They found that the strains in the Peruvian remains were most similar to a strain found in seals and sea lions.
"Our results show unequivocal evidence of human infection caused by pinnipeds (sea lions and seals) in pre-Columbian South America. Within the past 2,500 years, the marine animals likely contracted the disease from an African host species and carried it across the ocean to coastal people in South America," says Stone.
