[Mycobacterium infection in prehistoric humans: co-evolution in remote ages]

The introduction of agriculture and animal husbandry at the end of the Mesolithic era, despite enabling a significant demographic growth through an increase in food storage and availability, caused new infectious noxae to enter the pathocoenosis. However in the Palaeolithic era, hunter-gatherers were already in contact with infectious diseases of animal origin, albeit episodically. Modern biomedical technologies allow us to estimate, with better approximation, how long mankind has been in contact with Mycobacterium tuberculosis. Archaeological finds, including human and animal remains (especially the aurochs), are particularly studied by palaeopathologists, as mycobacteria frequently cause bone involvement and this characteristic is of particular interest for palaeopathological (even macroscopic) studies; the interest is to detect the ancient DNA of MT, which is the cause of bone tuberculosis in skeletal remains as well as in mummies. According to our present knowledge, palaeopathological findings, confirmed by molecular techniques, suggest that tuberculosis in human skeletons goes back at most to 9000 years ago, while, in a veterinary environment, the most ancient DNA of MTBC to be detected in an American bison dates back about 17,000 years. The possibility of discovering archaeological finds making even more ancient human remains available leaves opens up the possibility of dating back to previous eras the transmission of MTBC infection to mankind. Phylogenetic works examining the available materials (DNAa) suggest that Mycobacterium tuberculosis, the cause of tuberculosis infection in humans and cattle (Aurochs), would have had a co-evolutionary process. On the basis of recent phylogenetic studies, the MTBC genome would have had a wide span of time to reach a suitable adjustment, co-evolving in geographical environments both at high and low host density. It is likely that the strains that did not show this strong "flexibility" underwent extinction, in favour of more versatile, adaptable strains, that are able to infect susceptible hosts "always" and in any environmental condition.