Magellanic penguins strut their stuff on the rocky shoreline of Argentina's Punta Tombo, home to the largest colony of the birds in the world. Craig Lovell/Corbis hide caption

toggle caption Craig Lovell/Corbis

Charles, Prince of Wales, smells before tasting some ice cream during a visit to Gloucestershire. Maybe he was sniffing for fat? Barry Batchelor/Getty Images hide caption

toggle caption Barry Batchelor/Getty Images

Some men take testosterone hoping to boost energy and libido, or to build strength. But at what risk? iStockphoto hide caption

toggle caption iStockphoto

Playing outside can help kids — and their parents — maintain a healthy weight. iStockphoto hide caption

toggle caption iStockphoto

Love your hair. Artists' depictions of a Neanderthal man and woman at the Neanderthal Museum in Mettmann, Germany. Martin Meissner/AP hide caption

toggle caption Martin Meissner/AP

A new study on lactose tolerance among early farmers in Spain challenges a leading theory that humans developed an appetite for milk to avoid calcium deficiency. iStock hide caption

toggle caption iStock

A mouse embryo grows from stem cells made by stressing blood cells with acid. The blood cells are tagged with a protein that creates green light. Courtesy of Haruko Obokata hide caption

toggle caption Courtesy of Haruko Obokata

Graduate student Jennifer Klunk of McMaster University examines a tooth used to decode the genome of the ancient plague. Courtesy of McMaster University hide caption

toggle caption Courtesy of McMaster University

Clinical specialist Catey Funaiock took notes while observing a 5-year-old boy at the Marcus Autism Center, part of Children's Healthcare of Atlanta, in September. David Goldman/AP hide caption

toggle caption David Goldman/AP

The eastern Grand Canyon was about half-carved (to the level of the red cliffs above the hiker) from 15 million to 25 million years ago, an analysis published Sunday suggests. But the inner gorge was likely scooped out by the Colorado River in just the past 6 million years. Laura Crossey/University of New Mexico hide caption

toggle caption Laura Crossey/University of New Mexico

Ross' campsite on the West Antarctic ice sheet. For weeks, researchers eat, sleep and analyze data in these tents. Neil Ross/Newcastle University hide caption

toggle caption Neil Ross/Newcastle University

Computer networks and GPS systems are only possible because of the precision timekeeping of atomic clocks like the one above, says clockmaker and physicist Jun Ye. Ye Group and Baxley/JILA hide caption

toggle caption Ye Group and Baxley/JILA

NPR thanks our sponsors

Become an NPR sponsor