https://www.nytimes.com/2024/02/19/science/what-is-a-species.html Science|What Is a Species, Anyway? https://www.nytimes.com/2024/02/19/science/what-is-a-species.html * Share full article * * You have a preview view of this article while we are checking your access. When we have confirmed access, the full article content will load. [oakImage-1708101169087-articleLarge] Credit...Steve Holroyd/Alamy Skip to contentSkip to site index What Is a Species, Anyway? Some of the best known species on Earth may not be what they seem. Credit...Steve Holroyd/Alamy Supported by SKIP ADVERTISEMENT * Share full article * * Carl Zimmer By Carl Zimmer * Feb. 19, 2024Updated 5:02 p.m. ET Naturalists have been trying for centuries to catalog all of the species on Earth, and the effort remains one of the great unfinished jobs in science. So far, researchers have named about 2.3 million species, but there are millions -- perhaps even billions -- left to be discovered. As if this quest isn't hard enough, biologists cannot agree on what a species is. A 2021 survey found that practicing biologists used 16 different approaches to categorizing species. Any two of the scientists picked at random were overwhelmingly likely to use different ones. "Everyone uses the term, but no one knows what it is," said Michal Grabowski, a biologist at the University of Lodz in Poland. The debate over species is more than an academic pastime. In the current extinction crisis, scientists urgently need to take stock of the world's biological diversity. But even some of the best known species on Earth may not be what they seem. Take the giraffe. In 1758, the Swedish taxonomist Carl Linnaeus described a single species of giraffe: Giraffa camelopardalis. Although the species has declined in recent decades, 117,000 giraffes still survive across Africa, prompting an international conservation group to designate the species as vulnerable, rather than endangered. But some conservation biologists argue that giraffes are in great peril, because what looks like one species is actually four. Genetic studies have found that giraffe DNA falls into four distinct clusters: the Northern giraffe, the reticulated giraffe, the Masai giraffe and the Southern giraffe. [gif] Giraffa camelopardalis Northern giraffe Giraffa reticulata Reticulated giraffe Historic range Giraffa giraffa Southern giraffe Giraffa tippelskirchi Masai giraffe [gif] Giraffa camelopardalis Northern giraffe Giraffa reticulata Reticulated giraffe Historic range Giraffa giraffa Southern giraffe Giraffa tippelskirchi Masai giraffe By The New York Times. Images and map data from Raphael T.F. Coimbra et al., Current Biology; historic range from Giraffe Conservation Foundation [gif] Single historical species Species divergence Populations start to diverge into subspecies, which freely interbreed Gray zone: fewer hybrids between subspecies, gene exchange slows Separate species form after about 6 million years Present day [gif] Single historical species Populations start to diverge into subspecies, which freely interbreed Gray zone: fewer hybrids between subspecies, gene exchange slows Separate species form after a few million years Species divergence Present day By The New York Times [gif] Gammarus fossarum a European freshwater shrimp [gif] Gammarus fossarum a European freshwater shrimp By The New York Times. Photograph by Denis Copilas-Ciocianu [gif] 500 thousand years ago Ursus arctos Brown bear Ursus maritimus Polar bear 400 300 200 100 Present day [gif] 500 thousand years ago 400 300 200 100 Present day Ursus arctos Brown bear Ursus maritimus Polar bear By The New York Times. Photographs by Valdrin Xemaj/Reuters and Jeff Wilson/Disney+ [gif] Tyto alba Common barn owl As recognized by Bird Life International [gif] Tyto alba Common barn owl As recognized by Bird Life International By The New York Times. Photograph by David Tipling, via Alamy; map data from BirdLife International and Handbook of the Birds of the World (2022) We are having trouble retrieving the article content. Please enable JavaScript in your browser settings. --------------------------------------------------------------------- Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times. --------------------------------------------------------------------- Thank you for your patience while we verify access. Already a subscriber? Log in. Want all of The Times? Subscribe. Advertisement SKIP ADVERTISEMENT Site Index Site Information Navigation * (c) 2024 The New York Times Company * NYTCo * Contact Us * Accessibility * Work with us * Advertise * T Brand Studio * Your Ad Choices * Privacy Policy * Terms of Service * Terms of Sale * Site Map * Canada * International * Help * Subscriptions * Manage Privacy Preferences