It's been an interesting week for the story of ancient bacterial diseases. My post last Saturday discussed how the bacteria that cause leprosy and whooping cough might have been present in the early hominids. Lucas Brouwers (of Thoughtomics) wrote about bacteria of livestock that developed during the early domestication of animals. While looking for a paper to write about this week I found one on stomach ulcers in early humans and then commenter G Robbins pointed me towards her paper on leprosy found in early human skeletons!
So before I leave the ancient bacteria to go back to the modern ones I want to take one last look at the story of leprosy, and the exhumation of one of the earliest examples of the disease in action.
Unearthing Ancient Skeletons: Early Evidence for Leprosy
Although molecular clock and genetic data are all very well, the clearest way to show the presence of a disease in history is to find either something written about it or a skeleton that has clearly had it. Ancient historic texts mentioning leprosy have been found from the Bible, in ancient Sanskrit hymns and in Egyptian Ebers papyrus dated 1550 B.C. This kind of evidence is a little sketchy however, as descriptions of a disease are highly subjective - one persons leprosy is another persons eczema. They also rely on someone documenting the disease, which is likely to happen in the case of a city epidemic, but means that isolated rural cases may go largely ignored.
Leprosy apparently leaves quite a mark on the skeleton of an infected individual - what with degenerative joint disease, infections in the tibia (shinbone), and pathological changes to the front of the face, most particularly around the nose and mouth. Skeletons with leprosy have been found from 2nd century B.C in Egypt, 5th century B.C in Nubia and around 300 B.C in Thailand. This new skeleton however, is from 2000 B.C at Balathal in India, making it the oldest example found to date. The researchers have labelled it "individual 1997-1" and I shall call him Bob.
The date of Bob's burial was determined through carbon dating his skeleton and also by looking at the structure and architecture of the surrounding ancient houses. Ash and dirt surrounding the grave were also carbon-dated, to confirm that Bob had been buried between 2500–2000 B.C. Examining the pelvic architecture and overall build of the skeleton confirmed that Bob seemed to be biologically male. The state of the pubic symphysis and teeth and dental area placed Bob somewhere in his mid-thirties and the bone length suggested he stood around 1.7 meters tall.
A look at Bob's skeleton confirms that this is not a healthy individual. There is erosion of the bone around the outside of the nose (pathological rather than damage caused to the skeleton after death) and lesions around the eye sockets. The area associated with the soft palate and back of the throat/nose was also highly damaged, indicating inflammation and damage caused by the disease. Several of Bob's teeth had fallen out, and the remaining ones contained evidence of abscesses. Moving away from the skull, the rest of the skeleton shows serious joint infections, although parts of the skeleton are missing. All of these illnesses (detailed clearly in the reference for anyone with a greater interest in anatomy) are highly indicative of leprosy, particularly the damage to the facial areas.
There are other diseases that can produce some of these symptoms, but they usually show other symptoms as well. Some of the symptoms (particularly damage to the spinal joints) could be associated with tuberculosis, but an individual with tuberculosis would have much greater damage to several different spinal joints, which is not seen in Bob. Similarly, the parasite Leishmania causes infections that lead to lesions on the face, however it doesn't explain the specific spaces that are damaged in this skeleton. For the complete facial symptoms, bob would have to have suffered from leishmaniasis, oral infections and tooth loss, and that still does not adequately explain damage to the nasal spine. Leprosy looks like the most likely explanation.
There is a gory twist to this story though. In societies that existed around the time when Bob lived, adult skeletons are rare, as people were more likely to be cremated as part of the burial process. It's been suggested that in some areas, lepers were seen as unfit for cremation and may even have been buried alive. When poor old Bob was first put into the ground, he might not have even been dead...
For more information about this work, visit G. Robbins web page.
Ref 1: Robbins G, Tripathy VM, Misra VN, Mohanty RK, Shinde VS, Gray KM, & Schug MD (2009). Ancient skeletal evidence for leprosy in India (2000 B.C.). PloS one, 4 (5) PMID: 19479078