Although M. tuberculosis probably first emerged some 40,000 years ago in Africa, the disease did not take hold until humans took to farming... A previous analysis by his team had shown that the common ancestor of all the M. bacterium strains circulating today began spreading around 10,000 years ago in the ancient Fertile Crescent, a region stretching from Mesopotamia to the Nile Delta that was a cradle of agriculture... 4,987 samples of the Beijing lineage from 99 countries... the information to date the expansion of the lineage and show how the strains are related... the Beijing lineage did indeed emerge...