It is funny how people play with history. If we talk about an important “first” that is viewed in a positive light … the origin of beer for instance … the slightest evidence will be used by the people of a given region to claim primacy. Also, since Africa almost always gets the shaft in this regard, all else being equal, an early African occurrence of something good will be assumed as not definitive, but vague evidence of the non-African first occurrence will be taken more seriously. Seriously.

Now, we have an important finding with the opposite effect: Whence did Leprosy first come? For some time, the main contenders have been South Asia and East Africa for (although that is based on a fairly weak argument). Now there is evidence of the earliest Leprosy being form South Asia. That in and of itself is interesting and the paper just out moments ago in PLoS is important. But what I fund funny (not in the “ha ha” funny way exactly) is that despite the recent shoring up of the Asian Origin model for Leprosy, the concususion seems to be that all that is lacking to support the African Origin for this desease … being treated here as though it was a leper … is, well, actual evidence. And in the absence of evidence, we’ll just pick the African Origin.

But never mind that. I’ll jump back on my high horse regarding the Anti-African Bias later. For now, let’s look at the evidence being reported in this new paper.

Leprosy is caused by Mycobacterium leprae and is one of those diseases that paleopathologists really love because it produces traces visible on bone. Leprosy is found in armadillos and can be induced in some rodents and primates, and occurs naturally (or so it is thought) in Cercocebus atys, so there are reasonable animal models (for the bone traces) and it has been around long enough that it is probably safe to say that we more or less know it when we see it. (N.B.: The paper at hand does not recognize the Mangabey connection, which is either a lack on the part of the authors or on my part, so let’s leave this connection as subject to revision.) You know of leprosy because of its significant social stigma and all the cultural trappings that go a long with that unnecessary and ethically questionable approach to this disease. Likely, that social stigma relates to the appearance of leprosy in the written record, where previously it was well documented and accepted by historians back to about 2,600 years ago. The present find seems to allow the interpretation of writing in the Sanskrit Atharva Veda as being about leprosy instead of some other disease.

It had previously been reported that Mycobacterium originated in Africa during the Late Pleistocene and spreading elsewhere after 40,000 b.p. At the same time, it was suggested that the same genetic analysis evinced a Late Holocene origin of the disease in. The present paper reports the observation of leprosy in skeletal material from around 2000 B.C. in Rajasthan, India, at the site of Balathal. Balathal was a large agrarian settlement peripheral to the Harappan (Indus) Civilization.

From a press release for this paper:

The presence of leprosy in India toward the end of this period indicates that M. leprae existed in South Asia at least 4000 years ago. This suggests that there may be some validity to Pinhasi and colleagues hypothesis that the disease spread between Africa and Asia during a period of incipient urbanization, increasing population density, and regular inter-continental trade networks. Dr. Robbins is currently attempting to recover ancient DNA from the skeleton to determine if the strain of M. leprae infecting the individual from Balathal is similar to strains common in Africa, Asia and Europe today. If it is successful, this work could shed additional light on the origin and transmission routes of this disease.

The presence of leprosy at Balathal 4000 years ago also supports translations of the Eber’s papyrus in Egypt and a Sanskrit text in India (the Atharva Veda) that refer to the disease as early as 1550 B.C. The Atharva Veda is a set of Sanskrit hymns devoted to describing health problems, their causes and treatments available in ancient India. Translations of leprosy have been questioned because it is difficult to perform a differential diagnosis on descriptions in such ancient texts particularly since diagnosis was not why the conditions were being described. The evidence from Balathal indicates that it is possible that the authors were describing leprosy as the disease was present in the subcontinent in prehistoric times.

It is possible that there are alternative interpretations of the bone evidence used to infer leprosy, but future DNA study may rule those alternatives out. At the moment, however, it is a reasonable interpretation given the fairly blatant way in which leprosy is manifest in human bones.

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