Conservation policies should be embracing the insights into evolutionary history revealed by the refinement of taxonomic knowledge. Stephen Garnett and Les Christidis instead view these refinements as “taxonomy anarchy” that destabilizes species lists (Nature 546, 25–27; 2017).

They argue that taxonomic inflation can artificially increase the count of species under threat, citing a doubling in the number of recognized ungulate species. But, as well as updating classifications scarcely changed since the nineteenth century (see C. G. Groves and P. R. Grubb Ungulate Taxonomy; Johns Hopkins Univ. Press, 2011), that doubling of diversity highlights the high conservation priority both of the spiral-horned antelopes in African biodiversity hotspots and the evolutionarily distinct lineages of goats and sheep in Northern Hemisphere mountain ranges.

In mapping the evolutionary history of what it classifies, a taxonomy is much more than a species list. We see aspirations to stabilize taxonomy as a cul-de-sac that further isolates conservation policy from science. A proactive strategy should incorporate this new knowledge to mitigate the impacts of unprecedented global change on ecosystems and their dependent species.