If the results were artifacts of contamination at specific laboratories or of some other systematic error, independent analysis should produce different results.

The results of the independent testing were consistent with the original findings.

Human mitochondrial DNA was again identified in coprolites from the pre-Clovis layers, and the haplogroups identified were again consistent with Native American founding lineages.

This consistency across independent laboratories, analyzing different specimens from the same context, substantially strengthened the credibility of the DNA evidence.

The 2012 paper also reported the discovery of artifacts that added an important new dimension to the Paisley evidence.

Western Stemmed Points and the Technology Question