Human and domesticated animal environmental DNA as bioassays of the Anthropocene

Human and domesticated animal sequences, commonly detected in environmental DNA (eDNA) metabarcoding studies, are routinely excluded from analysis. Here we suggest that reporting human and domesticated animal eDNA results might open new lines of investigation. For example, the relative abundance of human and domesticated animal eDNA as compared to that of wild vertebrate species might provide an index of human impact on local biota. Such an index could be applied to sites ranging from urban harbors to remote villages, and possibly to analyze historical samples. Various potential sources of contamination complicate the picture, but it should be possible to develop procedures that minimize risk of DNA introduction during collection and processing. Our near-term recommendation is to encourage inclusion of human and domesticated animal data in eDNA publications as an incentive for discovery, to lift quality controls, and to collectively contribute to new vistas that eDNA science might open.