Taphoi wrote:
But extreme caution is advisable. Previous attempts to obtain DNA from even modern cremations have been very unsuccessful. Lots of DNA signal from the remains, but virtually all due to contamination of the ashes.
Modern cremations are rather different to ancient ones - the temperatures are higher (1,000-1,500 degrees c.) and of longer duration ( several hours) than in the past. In addition, when the remains including fragments of bone are removed, modern morticians grind all these particles to the fine powder that is commonly seen deposited in urns. The report Taphoi refers to points out that probably most of the contamination occurs during the handling and grinding process.
Philip II's remains are rather different in that his body was burnt in an oven , rather than on an open pyre. It may have reached temperatures as high as 900 degrees c and the cremation was probably 60-90 minutes rather than several hours. The result was that the skeleton remained almost intact, albeit with fractures and warping of the skull bones consistent with the corpse being burnt fleshed. So does this increase the prospect of DNA being recovered ?
Alas, it would seem not. Experimentation has focused on the correlations between heat and the preservation of
DNA, dental pulp and albumin. Tsuchimochi et al. (2002) found that DNA amplification and
typing of dental pulp was successful up to a temperature of 300C but not at higher temperatures.[The DNA sample which came from "Myrtis", the 11 year old girl who died of typhoid fever in the Great Plague of Athens in 430 BC linked in Efstathios' post came from dental pulp, but she was not cremated.]
Duffy et al. (1991) described a procedure to facilitate sex chromatin counts from tooth pulp cells
but noted that the extent and duration of heat as well as the extent of flesh present affect it.
Cattaneo et al. (1994) added that human albumin survives cremation up to temperatures of 300C
but no higher. Bone integrity and exposure to water affect protein survival in such cases (Cattaneo
et al. 1995). Although Sanjantila et al. (1991) reported successful DNA typing on all 26 samples
from 10 fire victims exhibiting extensive charring, Cattaneo et al. (1999) reported that no mitochondrial
DNA samples could be amplified in bone experiments with temperatures reaching 800 to 1200C.
Since Philip II was cremated at a temperature of up to 900 C, on the face of it, it would seem impossible to recover mitochondrial or other DNA. Taphoi would seem to be correct in urging caution about the possibility of results.
Yet the scientists at Manchester, the world's premier facility for this sort of thing, are of course well aware of this but clearly would not be taking on the task if they believed success was impossible. Have techniques improved in the last 10 years or so, so as to make DNA recovery from cremated remains possible ?
Contamination from handling the remains should not be an issue. It can be eliminated by taking a sample from the interior, by drilling into a tooth or bone, so taking DNA from all the archaeologists etc should not be necessary.
I guess we can but wait and see......................