Contamination deamination

This strikes me as a problem:

Furthermore, we demonstrate that in this dataset, the damage rate of the old contaminant sequences is indistinguishable from that of the endogenous DNA sequences. As such, the commonly used argument that miscoding lesions observed among cloned aDNA sequences can be used to support data authenticity, is misleading in scenarios where the presence of old contaminant sequences is possible.

That's from the abstract of a new paper in MBE by María Lourdes Sampietro and colleagues (via Dienekes, who has some additional commentary).

References:

Sampietro ML, Gilbert MTP, Lao O, Caramelli D, Lari M, Bertranpetit J, Lalueza-Fox C. 2006. Tracking down human contamination in ancient human teeth. Mol Biol Evol (advance access) Abstract