Robben brought tuberculosis to America

DNA analyzes of pre-Columbian mummies relieve Columbus and Co

Pre-Columbian Indian with tuberculosis and seal. © Leonardo Gonzalez
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Not the Spanish conquerors, but seals brought tuberculosis to America. Already a thousand years ago, infected animals crossed the Atlantic. The natives became infected as they ate the seal meat. This is proven by DNA analyzes of three Peruvian mummies that died 1, 000 years ago. Although Columbus and Co are not relieved, because they also brought tuberculosis, but the first were seals and sea lions from Africa, according to the researchers in the journal "Nature".

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Tuberculosis is one of the major epidemics of humanity, despite antibiotics still die today one to two million people per year of this bacterial infection. The causative agent of tuberculosis may have accompanied humans for some 70, 000 years, as researchers discovered in 2013. Thus, even the early representatives of Homo sapiens in Africa could have suffered from this disease, with the spread of humans the pathogen then reached Europe and Asia.

"Souvenirs" from Columbus and Co?

How the epidemic reached the Americas, however, remained unclear for a long time. Because the Spanish conquerors also imported other diseases from Europe to the New World, it was obvious that they also had tuberculosis. However, the strains of tuberculosis that are common in Europe and America today are very similar.

But something did not fit into the picture: some mummies and skeletons from the pre-Columbian era already show bone changes typical of tuberculosis. The disease must therefore have been present on the continent several hundred years earlier. But where did she come from? display

Searching for clues in mummy DNA

To find out, Kirsten Bos from the University of Tübingen and her colleagues went on a genetic search: They analyzed bone samples from 68 skeletons from the New World and searched specifically for the DNA of Mycobacterium tuberculosis. Three of the approximately 1, 000-year-old mummies from the Chiribaya culture of Peru found them. By comparing them with various tuberculosis strains known today, the researchers were able to determine the relationship and origin of the pre-Columbian plague.

However, the result of these evaluations was quite surprising: The presence of mummies in the pathogen was most closely related to a tuberculosis strain, which occurs today only in seals and sea lions. "That was completely unexpected, " says co-author Sebastien Gagneux of the Swiss Tropical Institute and the University of Basel. This strain causes disease in humans today, but it is very rare and certainly not responsible for the usual tuberculosis infections in humans. "

South American seabirds (Arctocephalus australis) - did their ancestors bring along tuberculosis? Ricardo Bastida

Seal hunting with consequences

Nevertheless, this type of pathogen finally provides a plausible answer to how the disease reached the New World. According to the researchers, the scenario is likely to be as follows: Approximately 2, 500 years ago, seals in Africa became infected with tuberculosis in another species. Some time later, some of these animals swam across the Atlantic that seals can do this, has long been known. They settled down along the South American coast, but they encountered a new enemy: the indigenous people living there.

These coastal inhabitants lived from fishing, but also hunted seals and ate their meat. They were probably infected with tuberculosis. By dating the skeletons and comparing the pathogen DNA, the researchers conclude that all three cases could be traced to a single transmission of this kind.

Over time, this pathogen then spread through mutual contagion in the New World, but was then displaced by the arrival of the Spaniards by the newly-launched European bacterial strain. Although the conquerors brought tuberculosis to America, they were not the first. (Nature, 2014; doi: 10.1038 / nature13591)

(Nature / University T bingen, 21.08.2014 - NPO)