Researchers examining ancient tuberculosis genomes are assembling pieces of this complicated evolutionary puzzle, now proposing that the disease predates the arrival of European settlers in the Americas and that early TB strains traveled a long distance on land.
As specified in a EureAlert! report, TB is the second most common cause of death globally by an infectious pathogen, "COVID-19 being the first." Nevertheless, many aspects of the long history of TB stay controversial.
Building on the discovery in 2014 that the occurrence of TB in Peru possibly came from marine mammals such as sea lions and seals, a recently published study validated those discoveries and detected in those who lived somewhere close to the coast, proposing such infections were not the result of direct spread from seals although instead resulted from one or more spillover occurrences where the pathogen is moving from one species to another.
The team of researchers, co-led by Tanvi Honap, a research assistant professor of anthropology at Dodge Family College of Arts and Sciences at the University of Oklahoma; and Ashild Vagene from the Section of Evolutionary Genomics, GLOBE Institute at the University of Copenhagen, were able to recover three new ancient TB genomes.
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Peru is a South American country with a more highly contagious resistant strain of tuberculosis. Authorities record 30,000 new cases every year, of which 60% are in its capital, Lima, especially in highly populated suburbs where living conditions lack basic hygienic services and running water.
Ancient TB Genomes
According to Honap, the said three new cases of pre-contact-era South American TB came from human remains coming from inland archeological areas, two of which are located in the highlands of the Colombian Andes.
He also said that all of these three ancient TB genomes are similar to M. pinnipedii, the same TB strain that exists in ancient coastal Peruvian people and modern-day sea lions and seals.
The researchers, including scientists from the Max Planck Institute of Evolutionary Anthropology and Arizona University, employed "archeological evidence and stable isotope TB spread was most possible from the bacterium that jumps to other species.
According to a similar Bioengineer.org report, Vagene explained the TB bacterium could cause infection to several mammalian species, and thus, there are many candidates for its terrestrial dispersal, which includes humans themselves.
M. Pinnipedii Strain Brought Inland Through Animal Life
According to Honap, Colombia has a great range of terrestrial mammals. Therefore, "M. pinnipedii could have been brought inland through the animal life."
Or, the co-study lead added, in a possible scenario, it could have been brought inland via human-to-human spread facilitated by trade routes or both combined.
One of the study's contributors Anne Stone, also a specialist in the evolutionary history of TB, sees their findings from the study, Geographically dispersed zoonotic tuberculosis in pre-contact South American human populations, published in the Nature Communications journal, as an opportunity for deeper discovery into the ecology of the disease in the Americas prior to the colonial period.
Stone explained, it is an exciting time in prehistoric DNA study, "as we can now look at genome-level differences" in these ancient pathogens and follow their movements throughout the continents and beyond.
Related report about ancient TB strain transmission is shown on Today's Sciencology's YouTube video below:
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