Fig. 3: M.TB structuring and preservation in archeological human remains.

The red and blue dots indicate body sites from which ancient M.TB DNA has been successfully recovered using NGS techniques. Red dots represent successful recoveries from mummified remains where soft tissue had been preserved, with positive samples taken from a rib bone (Kay et al. 2015), a calcified lung nodule (Sabin et al. 2020), soft tissue from the lungs (Kay et al. 2015), and soft tissue taken from the abdominal cavity (Kay et al. 2015). Blue dots represent successful recoveries from skeletonized remains (Bos et al. 2014). Published positive findings from skeletonized remains have been limited to vertebrae as of the writing of this paper. In the majority of cases, only one sampling site is represented per individual. The diversity discovered in an individual sample may not be representative of the total infection population across different subpopulations within a host. In addition, the stochasticity of DNA preservation in terms of ubiquitous contamination, fragmentation, and cytosine-to-uracil deamination poses barriers to accurate reconstruction of bacterial population diversity during life.