Monday, August 22, 2005

632: The Tubercular Hominid

The Tubercular Hominid: Corante > The Loom >:

French researchers have found that people in Djibouti carry strains of TB that are significantly different than anything seen before. They have many more genetic differences than have been found in human TB strains from anywhere else in the world. Yet they are more closely related to other human TB than to the Mycobacterium species that infect cattle and other animals. The scientists then turned the mutations of the Djibouti strains into a molecular clock. They estimate that the ancestor of today's human TB existed some three million years. The results have just been published in the new open access journal PLOS Pathogens.

If tuberculosis was infecting our ancestors three million years ago, it was infecting early, small-brained hominids. All of the hominids known from that time lived in Africa, and hominids would not be found outside the continent for over a million years. Our own species is believed to have evolved much later in Africa, and to have spread to Asia and Europe roughly 50,000 years ago. So it's telling that all these ancient strains are found in Africa, not far from some of the richest lodes of hominid fossils in Ethiopia. The genetic diversity of these bacteria reflects the genetic diversity of living Africans.
The evolution of TB.