 Has Devitt made the case for intrinsic essentialism? Perhaps not. Once again, why are certain organisms members of species S? According to our best biological theory, if S is an interbreeding species, then those organisms have intrinsic reproductive mechanisms that allow them to interbreed with one another. However, we do not know which intrinsic mechanisms are mechanisms that cause an organism to be a member of a particular species. We need some way of determining which mechanisms cause an organism to be a member of one species versus a member of another species. Here we must turn to relations: particular population and genealogical relations among organisms. The answer to why particular reproductive mechanisms are mechanisms of species S is that those mechanisms occur in organisms whose populations are genealogically connected in a single lineage. Relations are explanatorily prior in explaining taxon identity, not intrinsic properties.