Addressing this concern required additional evidence — specifically, evidence that the coprolites themselves were human, not just evidence that the DNA in them was genuinely old.

The Coprolite Identity Problem

The identification of a coprolite as human is not as simple as it might initially appear.

Dried feces from different species can be surprisingly similar in gross morphology, particularly after the taphonomic processes of desiccation, compaction, and mineralization have modified their original character.

And in a cave that has been used by multiple species — humans, carnivores, rodents, and other animals — over thousands of years, the coprolites from different producers will all be mixed together in the same sediment.

The 2008 paper had relied on a combination of morphological assessment (the physical characteristics of the coprolites, including their shape, size, and apparent internal structure), dietary content (the types of food remains identifiable within the specimens), and the DNA results themselves to identify specific specimens as human.