A new theory suggests seals and sea lions brought tuberculosis to the New World - not European explorers, as was previously believed, The Daily Mail reported on Thursday.
Scientists believe the marine animals brought the disease to South America long before Christopher Columbus sailed the ocean blue in 1492.
While estimations vary, it is believed 95 percent of the 20 million people living in the Americas before the Europeans arrived were killed by what they thought was a new disease carried by explorers. A team of anthropological geneticists at Arizona State University examined TB DNA from 1,000-year-old skeletons found in Peru and compared them to a database of modern genes.
They uncovered a definitive relationship to TB lineages in animals, especially seals and sea lions. Their study, published in the journal Nature, describes "unequivocal evidence" that TB spread to American Indian populations before any explorers arrived.
Once European tuberculosis strains arrived in the Americas, they completely replaced the animal strains, scientists believe.
"It is likely that the new European strain, which is more virulent, was a culprit - particularly since tuberculosis is really good at spreading during times of social crowding and distress," Anna Stone, one of the researchers, told The Daily Mail.
The pathogen has the largest strain varieties in Africa, suggesting it originated there, and then spread. The study supports the idea that humans passed the disease to animals and within the last 2,500 years, sea life carried the disease from Africa to South America, where they passed it back to humans.
"The connection to seals and sea lions is important to explain how a mammalian-adapted pathogen that evolved in Africa around 6,000 years ago could have reached Peru 5,000 years later," said Johannes Kraus, one of the other scientists who studied the case.
