Neither result alone was decisive; ancient DNA without a secure age tells you about biology but not about when, and radiocarbon dating of organic material without biological identification tells you about age but not about whose material is being dated.

Together, they established both who and when.

The second was the convergence of independent laboratory testing with the original DNA results.

When different ancient DNA laboratories, analyzing different specimens from the same context without knowledge of the original results, obtained similar haplogroup identifications, the probability that the original results were laboratory-specific contamination artifacts decreased substantially.

Independent replication is the gold standard for scientific validation, and the independent testing component of the 2012 research program was methodologically important precisely because it addressed the most serious concern about laboratory-specific contamination.

The third — and most powerful — was the convergence of fecal lipid biomarker chemistry with the DNA evidence.