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Could the spread of tuberculosis come from seals? Study says yes

After a remarkable analysis of bacterial DNA from 1,000-year-old mummies, scientists have proposed a new hypothesis for how tuberculosis arose and spread around the world.

The disease originated less than 6,000 years ago in Africa, they say, and took a surprising route to reach the New World: It was carried across the Atlantic by seals.

The new study, published in the journal Nature, has already provoked strong reactions from other scientists.

Tuberculosis has long been one of the deadliest diseases. In 2012, 8.6 million people became ill with this infection, and it caused 1.3 million deaths, according to the World Health Organization. The invading bacterium, Mycobacterium tuberculosis, attacks the lungs, where it causes widespread scarring.

In the new paper, the team proposes that humans acquired tuberculosis in Africa around 5,000 years ago. The disease spread to people across the Old World along trade routes. Meanwhile, Africans also spread the disease to animals such as cows and goats.

Seals that hauled out onto African beaches to raise their pups became infected. The bacteria then spread through seal populations until it reached South America. Ancient hunters there became infected when they handled contaminated meat.

Until further research is done, Brown said he would keep an open mind.

“But I’d really like them to be correct,” he said, “because it is going to be fun rearranging all the deck chairs in my brain to accommodate this new idea.”



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