Human intestinal bacteria transform dietary cholesterol into specific compounds, including coprostanol and its related molecules, through a well-characterized metabolic pathway.

While other mammals also produce fecal sterols, the specific ratios and the specific compounds produced by different species differ in ways that can be used to distinguish human from non-human fecal material.

This approach is fundamentally independent of DNA analysis.

It addresses the question “was this coprolite produced by a human or a non-human animal?” through a biochemical route that does not rely on the sequence of the DNA found in the specimen.

If the lipid biomarker analysis identifies a coprolite as human, and the DNA analysis independently identifies human DNA in the same specimen, the two lines of evidence are mutually reinforcing in a way that neither could be alone.