All 2.3 Million Species Are Mapped into a Single Circle of Life

Lineages of all known species on earth are finally pieced together

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Since Charles Darwin's day, biologists have depicted how new organisms evolve from old ones by adding branches to numerous trees that represent portions of the animal, plant and microbial kingdoms. Researchers from a dozen institutions recently completed a three-year effort to combine tens of thousands of trees into one diagram, most readable as a circle (below). The lines inside the circle represent all 2.3 million species that have been named. Biologists have genetic sequences for only about 5 percent of them, however; as more are finished, the relationships within and across groups of species may change. Experts estimate that up to 8.7 million species may inhabit the planet (about 15,000 are discovered every year). “We expect the circle to broaden,” says Karen Cranston, a computational evolutionary biologist at Duke University.

Anyone can propose updates to the database (OpenTreeOfLife.org). Greater detail could improve understanding of evolution and help scientists invent drugs, make crops more productive and better control infectious diseases.

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Credit: Stephen Smith; Source: “Synthesis of Phylogeny and Taxonomy into a Comprehensive Tree of Life,” by Cody E. Hinchliff et al., in Proceedings of the National Academy of Sciences USA, Vol. 112, No. 41; October 13, 2015

Mark Fischetti was a senior editor at Scientific American for nearly 20 years and covered sustainability issues, including climate, environment, energy, and more. He assigned and edited feature articles and news by journalists and scientists and also wrote in those formats. He was founding managing editor of two spin-off magazines: Scientific American Mind and Scientific American Earth 3.0. His 2001 article “Drowning New Orleans” predicted the widespread disaster that a storm like Hurricane Katrina would impose on the city. Fischetti has written as a freelancer for the New York Times, Sports Illustrated, Smithsonian and many other outlets. He co-authored the book Weaving the Web with Tim Berners-Lee, inventor of the World Wide Web, which tells the real story of how the Web was created. He also co-authored The New Killer Diseases with microbiologist Elinor Levy. Fischetti has a physics degree and has twice served as Attaway Fellow in Civic Culture at Centenary College of Louisiana, which awarded him an honorary doctorate. In 2021 he received the American Geophysical Union’s Robert C. Cowen Award for Sustained Achievement in Science Journalism. He has appeared on NBC’s Meet the Press, CNN, the History Channel, NPR News and many radio stations.

More by Mark Fischetti
SA Special Editions Vol 25 Issue 5sThis article was published with the title “The Circle of Life” in SA Special Editions Vol. 25 No. 5s (), p. 112
doi:10.1038/scientificamericansciencestories1216-112

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