Around 2600 years ago in Egypt, a woman called Irtyersenu died. She was mummified and buried at the necropolis at Thebes, where she remained for over two millennia before being unearthed in 1819. Her well-preserved body was brought to the British Museum where it was examined by the physician and obstetrician Augustus Bozzi Granville. It was the first ever medical autopsy of an Egyptian mummy and Granville presented his results to the Royal Society in 1825. His conclusion: Ityersenu died of ovarian cancer.
The mummification techniques of ancient Egypt were so good that Irtyersenu's corpse still retained many soft tissues, and most of her organs intact. In particular, an unusual mass around her right ovary caught Granville's attention. He interpreted it as a cancer and the cause of the lady's death. But according to later studies, the tumour was a benign one, far from the fatal affliction that Granville envisaged.
Some scientists have since blamed malaria for Irtyersenu's death but Helen Donoghue from University College London believes she has uncovered the true culprit - tuberculosis.
It's clear that tuberculosis was a big killer of ancient Egyptians. Scientists have found DNA from Mycoplasma tuberculosis, the bacterium that causes the disease, in several mummies from both genders and all social circles. Donoghue managed to do the same forsamples of Ityersenu's lung, gall bladder and other tissues.
But, as other groups have found, extracting DNA from this particular mummy is unusually difficult. Ityersenu was mummified using an unusual technique and while her organs have been incomparably preserved, her DNA has not. Compared to other mummies, her genetic material degrades with uncharacteristic ease. So Donoghue's results weren't conclusive. She needed more evidence.
She found it by detecting traces of mycolic acid and related chemicals in both of the mummy's thigh-bones and one sample of lung tissue. These substances are signatures of M.tuberculosis and they must have come from the bacteria's cell walls. This was the smoking gun that Donoghue needed to confirm her diagnosis - the acids are far more stable than DNA and they can be detected in very low quantities.
Even so, Donoghue's team took every precaution to prevent their precious samples from being contaminated with modern molecules. None of the labs which tested the samples had ever worked with tuberculosis. They took extreme care to clean equipment before experiments and avoid sharing their tools with groups working on other projects.
Donoghue thinks that the tuberculosis started in Irtyersenu's chest and eventually spread to the rest of her body. Compared to the alternative theory of malaria, her diagnosis is a much better fit for our knowledge of Irtyersenu's final days.
A second autopsy in 1994 suggested that she was wasting away before she died, succumbing to either a long-term illness or a lengthy bout of inactivity. Both possibilities are consistent with a long and losing battle against tuberculosis. It seems that twenty-six centuries after she died, Irtyersenu's true killer has finally been uncovered.
This is one of two papers I'm going to cover on diagnosing diseases in long-dead animals. The second is out tomorrow.
Reference: Donoghue, H., Lee, O., Minnikin, D., Besra, G., Taylor, J., & Spigelman, M. (2009). Tuberculosis in Dr Granville's mummy: a molecular re-examination of the earliest known Egyptian mummy to be scientifically examined and given a medical diagnosis Proceedings of the Royal Society B: Biological Sciences DOI: 10.1098/rspb.2009.1484