History of tuberculosis

Consumption, phthisis, scrofula, Pott's disease, and the White Plague are all terms used to refer to tuberculosis throughout history. It is generally accepted that Mycobacterium tuberculosis originated from other, more primitive organisms of the same genus Mycobacterium. In 2014, results of a new DNA study of a tuberculosis genome reconstructed from remains in southern Peru suggest that human tuberculosis is less than 6,000 years old. Even if researchers theorize that humans first acquired it in Africa about 5,000 years ago, there is evidence that the first tuberculosis infection happened about 9,000 years ago. It spread to other humans along trade routes. It also spread to domesticated animals in Africa, such as goats and cows. Seals and sea lions that bred on African beaches are believed to have acquired the disease and carried it across the Atlantic to South America. Hunters would have been the first humans to contract the disease there.

Scientific work investigating the evolutionary origins of the Mycobacterium tuberculosis complex has concluded that the most recent common ancestor of the complex was a human-specific pathogen, which underwent a population bottleneck. Analysis of mycobacterial interspersed repetitive units has allowed dating of the bottleneck to approximately 40,000 years ago, which corresponds to the period subsequent to the expansion of Homo sapiens sapiens out of Africa. This analysis of mycobacterial interspersed repetitive units also dated the Mycobacterium bovis lineage as dispersing approximately 6,000 years ago, which may be linked to animal domestication and early farming.

Human bones from the Neolithic show a presence of the bacteria. There have also been a claim of evidence of lesions characteristic of tuberculosis in a 500,000 years old Homo erectus fossile, although this finding is controversial.

Results of a genome study reported in 2014 suggest that tuberculosis is newer than previously thought. Scientists were able to recreate the genome of the bacteria from remains of 1,000-year-old skeletons in southern Peru. In dating the DNA, they found it was less than 6,000 years old. They also found it related most closely to a tuberculosis strain in seals, and have theorized that these animals were the mode of transmission from Africa to South America. The team from University of Tubingen believe that humans acquired the disease in Africa about 5,000 years ago. Their domesticated animals, such as goats and cows, contracted it from them. Seals acquired it when coming up on African beaches for breeding, and carried it across the Atlantic. In addition, TB spread via humans on the trade routes of the Old World. Other researchers have argued there is other evidence that suggests the tuberculosis bacteria is older than 6,000 years. This TB strain found in Peru is different from that prevalent today in the Americas, which is more closely related to a later Eurasian strain likely brought by European colonists. However, this result is criticised by other experts form the field, for instance because there is evidence of the presence of Mycobacterium tuberculosis in 9000 year old skeletal remains.

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