There are roughly 2.5 million known species on the planet, but scientists estimate that's only a fraction of the biodiversity on Earth. A new study shows we're finding new species like never before. ROB SCHMITZ, HOST: Robert May, a famed ecologist, posed a hypothetical question to the scientific community 15 years ago - if an alien spaceship landed on Earth, one of the first questions they would likely ask would be, how many distinct life forms? How many species live on your planet? Embarrassingly, May said, we would not have a good answer. NPR's Nate Rott reports on how that is changing. NATE ROTT, BYLINE: Think back real quick to your middle school biology class, to taxonomy, you know - domain, kingdom, phylum, class, order, family, genus, species. You remember that, right? That categorical system - what we all use to describe life on Earth - was invented in the 1700s by Swedish biologist Carl Linnaeus. And since then, scientists have described millions of species. JOHN WIENS: Currently, 2.5 million. And that's - again, that's described species. That's known species. ROTT: John Wiens is a professor in the department of ecology and evolutionary biology at the University of Arizona. And he's the coauthor of a new paper published in the journal Science Advances that looks at the history of species discovery, where it started, how it's evolved and where it's going. WIENS: Well, we went back to Linnaeus. Yeah. We went back to the 1750s. ROTT: And they found there was a slow ramping up of discovery over time. WIENS: And then it hits this peak around 1900, and then there's a dramatic drop in the early 1900s. And you can probably guess what that is. ROTT: Any guesses? WIENS: It's World War I. And it climbs back up again, and then - boom - World War II, and it falls back down again. And then it's been climbing ever since, and we're now uncharted territory, you know, the fastest rates of species description per year that we've ever seen. ROTT: An average of 17,000 newly discovered species every year, in large part, he says, because we're just better at looking. I feel like we spend so much time talking about whether or not there's life on other planets, but your paper shows that, like, we don't even really know how much life exists here. WIENS: Oh, yeah. No, the range in estimates of how many species are out there are from the low millions to the low trillions. ROTT: That's wild. WIENS: Yeah. And a lot of that uncertainty is associated with microbes. ROTT: Microscopic life that's understandably harder to find than some new species of cat. Wiens' best guess of how many species there are on the planet is between the low hundreds of millions to low billions. So he's got a wide landing pad. WIENS: But yeah, just, like, tons of species out there. We would say it's a poorly known planet that we live on. ROTT: Poorly known but improving. And Wiens says the more we can learn about what's living on Earth, the better because we can better protect what exists and, less altruistically, we can potentially benefit from what we find. Take Ozempic, the very much-in-vogue weight-loss drug. WIENS: The basis for it - it was inspired by Gila monster venom. ROTT: So who knows, he says, what else we might find. Nate Rott, NPR News. (SOUNDBITE OF CLEANSALT'S "A PINCH OF SALT / BITTER TEARS") Copyright © 2025 NPR. All rights reserved. Visit our website terms of use and permissions pages at www.npr.org for further information. Accuracy and availability of NPR transcripts may vary. Transcript text may be revised to correct errors or match updates to audio. Audio on npr.org may be edited after its original broadcast or publication. The authoritative record of NPR’s programming is the audio record.
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A new study reveals an unprecedented discovery of new species
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