Analysis of this damage pattern allows researchers to distinguish ancient from modern sequences and to estimate the degree of preservation of the ancient material.

For the Paisley coprolites, the ancient DNA team applied all of these standard contamination controls and additionally conducted the analysis at multiple independent laboratories.

The consistent detection of Native American founding haplogroups across multiple independent laboratories, using material from different specimens, provided strong evidence that the results were genuine rather than contamination artifacts.

The decision to conduct the analysis at multiple independent laboratories was not simply a procedural precaution; it was a substantive methodological choice that addressed the contamination concern directly.

If the haplogroup A2 and B2 sequences detected in the first laboratory had been contamination specific to that laboratory’s environment, the same sequences would not be expected to appear in analyses conducted at different laboratories with different personnel, different equipment, and different molecular biological environments.