Arthritis is a joint disease that can cause cartilage destruction and erosion of the bone, as well as tendon inflammation and rupture. Affected areas are highlighted in red in this enhanced X-ray.
Philippe Sellem/Paul Demri/ Voisin/Science Source
Max Planck Institute paleoanthropologist Jean-Jacques Hublin examines the new finds at Jebel Irhoud, in Morocco. The eye orbits of a crushed human skull more than 300,000 years old are visible just beyond his fingertip.
Rocky spent his first few years raised by people, and is particularly attuned to human speech and behavior, researchers say. But his remarkable ability to learn and match human pitch and common sounds of speech surprised them.
Mark Kaser/Courtesy of Indianapolis Zoo
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
A group of British researchers has a hunchthat 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.
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
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.
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
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
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.