National Geographic paleoartist John Gurche used fossils from a South African cave to reconstruct the face of Homo naledi, the newest addition to the genus Homo. Photo by Mark Thiessen/National Geographic hide caption

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A group of British researchers has a hunch that once ancient humans learned to cook, starchy foods like root vegetables or grasses could have given them a calorie bump that fueled the evolution of the human brain. Scott Sherrill-Mix/Flickr hide caption

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Horses, riders and runners crossed three streams in the course of their 22-mile race through the hills of central Wales. The average finish time was the same for both species — four hours. Ryan Kellman and Adam Cole/NPR's Skunk Bear hide caption

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An ancient stone tool unearthed at the excavation site near Kenya's Lake Turkana. It's not just the shape and sharp edges that suggest it was deliberately crafted, the researchers say, but also the dozens of stone flakes next to it that were part of the same kit. MPK-WTAP hide caption

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With the help of researcher Sabudo Boraru (right), anthropologist Chris Campisano, of Arizona State University, takes samples from the fossil-filled Ledi-Geraru project area in Ethiopia. The jawbone was found nearby. Courtesy of J Ramón Arrowsmith hide caption

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An example of a human precision grip — grasping a first metacarpal from the thumb of a specimen of Australopithecus africanus that's thought to be 2 to 3 million years old. T.L. Kivell & M. Skinner hide caption

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Farming helped fuel the rise of civilizations, but it may also have given us less robust bones. Leemage/UIG via Getty Images hide caption

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Rocky Juarez of the U.S. gets punched in the face in July 2010 by Jorge Linares of Venezuela during their WBA Fedelatin lightweight title fight in Las Vegas. Some researchers believe the human face evolved to take punches — without, of course, the boxing gloves. Steve Marcus/Reuters/Corbis hide caption

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Our popular image of Homo erectus as the proto-guy who whose human-like traits all emerged at once needs overhauling, some anthropologists say. Sylvain Entressangle/Science Source hide caption

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Signs of tuberculosis have been found in ancient Egyptian mummies, such as this one in London's British Museum. Klafubra/Wikimedia.org hide caption

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This model of a molar shows color-coded barium banding patterns that reveal weaning age. Ian Harrowell, Christine Austin, Manish Arora/Harvard School of Public Health hide caption

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