The 2020 study by Sistiaga and colleagues applied fecal lipid biomarker analysis to the Paisley coprolites.

The results confirmed that three pre-Clovis coprolites showed biomarker profiles consistent with human origin.

This was a genuinely significant contribution — it addressed one of the central criticisms of the 2008 paper through a method that the original criticism could not have anticipated.

But the 2020 paper also addressed the DNA movement concern in a way that was more candid than the 2008 paper had been: the authors acknowledged that DNA movement through the sediment was a real phenomenon that could not be ruled out for all specimens, and that the biomarker evidence was valuable precisely because it could establish human origin independently of the DNA evidence.

This was not a concession that the original DNA evidence was fraudulent — it was an honest acknowledgment that the DNA evidence alone had been insufficient to answer the coprolite identity question, and that the biomarker evidence was filling that gap.