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Among the deadliest infectious diseases on the planet might have been carried to the Americans by seals and sea lions, not European explorers as previously believed, claims new research published online Wednesday within the journal Nature.
Tuberculosis accounts for killing as many as 2 million people each year, and according to researchers from the Arizona State University as well as an international team of experts, scientists have long debated the origins of the disease. Their research indicates that its arrival within the New World likely predated those of other European diseases, including influenza and chicken pox.
ASU anthropological geneticist Anne Stone, Johannes Krause of the University of Tubingen in Germany and their colleagues analyzed pre-Columbian Mycobacterial tuberculosis genomes and figured the condition likely spread from humans in Africa to seals and sea lions. Consequently, those marine animals were the one who brought the condition to South America, transmitting it towards the natives living there before the first Europeans made landfall.
Based on Ed Yong of National Geographic, they of investigators analyzed three Peruvian skeletons which were approximately 1,000 years of age and had the warped spines and ribs that were indicative of the disease.
They extracted DNA from the skeletons that included sequences owned by Mycobacterium tuberculosis. The research authors calculated that these bacteria, which are the pathogens responsible for causing tuberculosis, last shared a common ancestor with modern M. tuberculosis strains approximately 6,000 years back.
“That was the first amaze,” Yong said, explaining that scientists had long believed tuberculosis was an old disease and that all the strains affecting humans started out a common ancestor living over 70,000 years back. The new research, however, reveals that this microbe was actually less than one-tenth the old.
“It’s not only the discrepancy that’s baffling,” the National Geographic reporter added. “By 6,000 years back, humans had already spread around the world, including all around the Americas. The land bridge that connected Asia and North America had for many years flooded. And it would be several millennia before any Europeans sailed across the Atlantic. Therefore if tuberculosis originated from Africa, how made it happen get into South usa?”
Yong continued to describe that the researchers considered many possibilities as to how the disease made the journey, originally suggesting seals facetiously. Even so, they compared the genomes of many specious of tuberculosis bacteria with seals and various other animals, including humans, cows, chimpanzees and goats. The fact is, the nearest relatives of the Peruvian strains were, in fact, those that originated from seals.
Kirsten Bos from the University of Tubingen told him that the researchers “had a good laugh” over the suggestion that seals might have been accountable for bringing the condition to the New World. “It seemed so silly,” she added. “We couldn’t believe that was exactly what the data was showing, but it was pretty clear.”
“The supply of tuberculosis within the New World long has been a question for researchers,” added Elizabeth Tran, Biological Anthropology program director within the National Science Foundation’s (NSF) Division of Behavioral and Cognitive Sciences. “This paper provides strong evidence that marine mammals may have been the likely culprits, bringing tuberculosis to South usa long before Europeans arrived there.”
However, Stone noted that European strains aren’t in the clear, as she and her colleagues hypothesize that when they did arrive in south america, they completely replaced the strains originally carried over through the aquatic animals. She asserted it’s not clear exactly what the timeframe for this replacement was, or what role they played in the deaths of 95 percent of the 20 million natives residing in the brand new World prior to the arrival of Europeans.
“This is a question that we hope to address in the future,” she said, adding it’s “likely that the new European strain, that is more virulent, was a culprit C particularly since tuberculosis is really proficient at spreading during times of social crowding and distress.”
