The oldest known leper

This week scientists have uncovered what they think is the world's oldest example of a leprosy victim.  This is a paper in the journal PLoS One and the pictures are absolutely stunning; to an osteoarchaeologist at least.

Gwen Robins and her colleagues, based at the Appalachian State University in North Carolina, have been working at a site in North-West India called Balathal.They have excavated a site which can be very quite reliably dated to about 2000BC, so 4000 years ago. There they've found the remains of a 37 year-old man, identified by looking at the shape of the pelvic bones, because men have different-shaped pelves to women. 

This skeleton shows bone changes which are very characteristic of leprosy.  If you look at the skull you can see what's called reactive flare on the surface coating of the bone above one of the eye sockets.  There's also a complete hole in the bone adjacent to the underside of the nose and there's also damage under one of the eye sockets and degeneration in the backbone.

For a long time people have said that there are a number of diseases that will cause similar bony changes like these: syphilis is one of them, osteomyelitis and tuberculosis are others. The reason this seems a good candidate for leprosy is because a) we can place it in space and time and b) it coincides with what we know people were doing at that time. There are historical records that go back to within 500 years of this: these are Sanskrit hymns which talk about an apparently similar disease. But until now there hasn't been any archaeological evidence to back it up.

It also coincides with what we know people were doing at this time.  One theory suggests leprosy originated originally in Africa and as people migrated out of East Africa perhaps they took it with them. Another theory suggests it didn't originate there at all and that it could have originated where this person was found, in India.  This body is a really important discovery because it coincides with early populations moving from nomadic hunter-gatherers to villages and towns supported by agriculture and keeping animals. They were therefore living more closely together and facilitating the spread of the disease. Leprosy is very low-infectivity but it is nonetheless an infectious illness. It needs people to be in close contact because only a small minority of the population are susceptible. You need a big population living together to get enough people spreading it around otherwise it would just die out.