About 300 years ago, Swedish naturalist Carl Linnaeus set out on a bold quest: to identify and name every living organism on Earth. Now celebrated as the father of modern taxonomy, he developed the binomial naming system and described more than 10,000 species of plants and animals. Since his time, scientists have continued to describe new species in the quest to uncover Earth's biodiversity.
According to a new University of Arizona-led study published in Science Advances, scientists are discovering species quicker than ever before, with more than 16,000 new species discovered each year. The trend shows no sign of slowing, and the team behind the new paper predicts that the biodiversity among certain groups, such as plants, fungi, arachnids, fishes and amphibians is richer than scientists originally thought.
"Some scientists have suggested that the pace of new species descriptions has slowed down and that this indicates that we are running out of new species to discover, but our results show the opposite," said John Wiens, a professor in the University of Arizona Department of Ecology and Evolutionary Biology , in the College of Science , and senior author of the paper. "In fact, we're finding new species at a faster rate than ever before."
The team analyzed the taxonomic histories of roughly 2 million species, spanning all groups of living organisms. Between 2015 and 2020 – the most recent period with comprehensive data – researchers documented an average of more than 16,000 new species each year, including more than 10,000 animals (dominated by arthropods and insects), 2,500 plants and 2,000 fungi.
"Our good news is that this rate of new species discovery far outpaces the rate of species extinctions, which we calculated to about 10 per year," said Wiens, pointing to another study he led that published in October . "These thousands of newly found species each year are not just microscopic organisms, but include insects, plants, fungi and even hundreds of new vertebrates."
More species than ever – and still more to come
Scientists are describing more species per year than at any point in history, Wiens and his co-authors found. The team also analyzed the rates of new species appearing over time to project how many species will be discovered and described in the future. For example, they projected that there might be as many 115,000 fish species and 41,000 amphibian species, even though there are only about 42,000 fish and 9,000 amphibian species described now. They also projected that the final number of plant species might be over a half million.
"As the famous ecologist Robert May said, if visiting aliens asked us how many species live on our planet, we would have no definitive answer," said Wiens. "Right now, we know of about 2.5 million species, but the true number may be in the tens or hundreds of millions or even the low billions."
For now, the scientists predict that the discovery rate of new living things will continue to increase. For example, scientists have currently identified around 1.1 million insect species, yet many scientists believe that the true number is somewhere around 6 million. In a previous paper , Wiens suggested it could even be in the ballpark of 20 million.
"Right now, most new species are identified by visible traits," said Wiens. "But as molecular tools improve, we will uncover even more cryptic species – organisms distinguishable only on a genetic level. This is especially promising for revealing more unique bacteria and fungi."
Benefits to humanity
"Discovering new species is important because these species can't be protected until they're scientifically described," Wiens added. "Documentation is the first step in conservation – we can't safeguard a species from extinction if we don't know it exists."
Additionally, the discovery of new species contributes to finding new natural products for human benefit. Some examples of natural products include GLP-1 receptor agonists, increasingly popular weight-loss drugs inspired by a hormone found in Gila monsters. Spider and snake venoms and many plants and fungi also contain natural products with potential medicinal applications, including treatments for pain and cancer.
Beyond medicine, many species have adaptations that can inspire human inventions, such as materials mimicking the "super-clinging" feet that allow geckos to climb up vertical surfaces.
"We're still just scratching the surface of what these species can do for humanity," Wiens said.
Going forward, the researchers plan to map where most new species are commonly found to identify geographic hotspots for undiscovered biodiversity. They are also interested in who is making the discoveries and are testing whether it has changed from predominantly European scientists to researchers documenting new species from their own countries.
"Even though Linnaeus' quest to identify species began 300 years ago, 15% of all known species have been discovered in just the past 20 years," Wiens said. "So much remains unknown, and each new discovery brings us closer to understanding and protecting the incredible biodiversity of life on our planet."
