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We need studies of where ancient DNA is localised, within samples

Posted by cooperative on 11 Apr 2009 at 13:47 GMT

In this paper and in ancient DNA studies generally, there does not seem to be any attempt to show where, in morphological terms, the ancient DNA is located. Knowing this could help us learn more about the conditions that enhance or reduce DNA preservation. For example, if soft tissues shrink and adhere to the internal surfaces of an insect exoskeleton, are there any areas of exoskeleton in which DNA preservation is better than other areas, because of the internal surface morphology? Or for sediments, are certain components of a sedimentary mix critical for DNA preservation - the silica components, or colloids of a certain diameter? There are many wonderful histological techniques for in situ detection of biomolecules - can these be applied ancient biological materials and sedimentary matrixes? I personally believe that the pores in silica-rich grinding stones may be an ideal environment for ancient DNA preservation, since such tools were used to grind biological materials and have often left microscopically visible residues embedded in their surfaces (fibres and starch for example). The fact that we zealously wash our modern mortars and pestles between DNA extractions suggests that there might be a possibility that our ancestors left traces of DNA on their tools. There is much scope here for experimental approaches to complement the ancient DNA work.

Competing interests declared: I have been working on ancient starch on grinding stones (with a student), and am seeking expressions of interest in extending the work on grinding stones to the DNA level (something that I cannot undertake myself)