A team of archaeologists working offshore from Haifa, Israel in the Mediterranean has discovered both direct and indirect evidence of human tuberculosis. This is important because, if confirmed, the TB cases date to 3,000 years earlier than expected: The disease should not be in skeletons this old. Also, this research seems to indicate that Tuberculosis did not originally arise in cattle to be later transmitted to humans, but rather, the other way around.
The site is called Alit-Yam, and it is a 9,000 year old Pre-Pottery Neolithic village. This site is about two or three hundred meters offshore at a depth of about 10 meters. The site was covered by the sea with rising post-glacial sea levels, but was probably coastal when it was occupied and demonstrates evidence of a partly maritime economy.
I remember hearing about this site from some of the people working on it during a visit to Haifa in late 1990. Stories of the underwater site were interspersed with a tour of gas-secure rooms and discussions of gas masks, all part of the preparation for being gassed by Sadam prior to the outset of the First Gulf War. But I digress.
Anyway, this site is also well known for its early cattle (among the earliest good evidence of domesticated cattle in the region) and some odd features such as a miniature Stonehenge-looking megalithic structure.
The finding being reported today includes bones showing lesions typical of TB on individuals from a burial thought to be of a mother and her infant. DNA testing seems to confirm the diagnosis.
From the press release:
An international collaborative team, led by Dr Helen Donoghue and Dr Mark Spigelman, UCL Centre for Infectious Diseases & International Health, conducted detailed analyses of the bones using scientific techniques that revealed DNA and cell wall lipids from Mycobacterium tuberculosis, the principal agent of human TB. The DNA was sufficiently well-preserved for molecular typing to be carried out and the analysis of the bacterial cell wall lipids by high performance liquid chromatography provided direct, confirmatory evidence of tuberculosis.
Dr Donoghue said: "What is fascinating is that the infecting organism is definitely the human strain of tuberculosis, in contrast to the original theory that human TB evolved from bovine TB after animal domestication. This gives us the best evidence yet that in a community with domesticated animals but before dairying, the infecting strain was actually the human pathogen. The presence of large numbers of animal bones shows that animals were an important food source, and this probably led to an increase in the human population that helped the TB to be maintained and spread.
"We were also able to show that the DNA of the strain of TB in these skeletons had lost a particular piece of DNA which is characteristic of a common family of strains present in the world today. The fact that this deletion had occurred 9000 years ago gives us a much better idea of the rate of change of the bacterium over time, and indicates an extremely long association with humans."
Dr Spigelman added: "Examining ancient human remains for the markers of TB is very important because it helps to aid our understanding of prehistoric tuberculosis and how it evolved. This then helps us improve our understanding of modern TB and how we might develop more effective treatments."
It really is a surprise that TB is not a zoonotic cattle to human disease, as previously believed. In fact, that is something I'd like to see confirmed. It may be the case that the movement of this disease in this early period is simply more complex than previously thought.
Hershkovitz I, Donoghue HD, Minnikin DE, Besra GS, Lee OY-C, et al. (2008) Detection and Molecular Characterization of 9000-Year-Old Mycobacterium tuberculosis from a Neolithic Settlement in the Eastern Mediterranean. PLoS ONE 3(10): e3426. doi:10.1371/journal.pone.0003426
Download the PLoS ONE paper here. http://dx.plos.org/10.1371/journal.pone.0003426
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Why the surprise at the origin? Is it simply that there were a lot more animals than people, and thus chances are in general favoring animal sources or is there something else special about people and TB?
Markk, I think what you are saying is not a surprise is not what they say happened.
No I was asking why there was surprise at the apparent non-animal origin of the TB found. Greg says he would like to see it confirmed, which is needed of course, but I was wondering why the thought it was of recent animal origin was so compelling, as opposed to this finding.
It still could ahve come from wild cattle.
I *think* that the assumed transmission was from cattle to humans via infected milk (which was the main transmission route in the historical period up until TT of dairy cattle). If you're going with human-to-cattle transmission, or transmission from cattle to humans before dairy farming began, then you need a new mechanism for transmission (since droplet infection, which was the main human-to-human mechanism, is unlikely unless you live in the building that your stock winter in).