Anthropologists in the United States are asserting that an understanding of the presence and patterns of disease to be observed in ancient human remains may help us to deal with diseases in the modern world. Their method of study is to combine palaeomicrobiology with palaeoepidemiology so that the questions may be asked, why a pathogen was present in a specimen, which members of a society were most affected by it, and whether it shows differences in our own time.
A commentary in the Lancet for April 8 observes that bacteria, viruses and parasites produce the same effects in mummified human remains as the organisms do in modern bodies. The great difference lies in their relative prevalence in the two societies. Modern research has enabled us to analyse diseases not only qualitatively but also quantitatively, thanks to the polymerase chain reaction and DNA analysis.
In France, tuberculosis, syphilis, leprosy, plague and influenza have now been studied in past societies, and may help to resolve questions about their transmission and animal reservoirs. For example, tuberculosis may have been brought to Britain in cattle brought in by the Romans.
In Britain, DNA from the leprosy bacillus has been sequenced from bone fragments dating from the 13th century, from Norse skeletons from Orkney. Leprosy was unknown here until Roman times and the earliest evidence for lepromatous leprosy comes from Tean in the Isles of Scilly, from the 7th century. In Scotland the oldest trace comes from an 8th century skull.
In late medieval times leprosy disappeared from the record, possibly because an icy period in the 16th century persuaded people to wear warmer clothing, and so reduced leprosy transmission. Syphilis, which leaves clear skeletal evidence, and the related yaws, has been found in Florida populations dating back 8,000 years, syphilis itself dating from 2,000 years ago from Colorado.
The benefits that studies of ancient DNA can bring to our own society include knowledge of animal reservoirs of human infections, and possibly suggestions for disease control in the face of increasing microbial resistance to antibiotics.