A loggerhead turtle was found oiled in the Gulf waters. It was cleaned on-site, then sent to Mote Marine Laboratory in Sarasota, Fla., for rehabilitation and monitoring. Christopher Joyce/NPR hide caption

itoggle caption Christopher Joyce/NPR

Almost 2 million gallons of oil dispersants were used to dilute the oil spill in the Gulf of Mexico, and though testing indicates the toxic chemical has largely dissipated in the water, scientists warn that the long-term effects are still unknown. Above, a dispersant plane passes over an oil skimmer in the Gulf of Mexico. Patrick Semansky/AP hide caption

itoggle caption Patrick Semansky/AP

Marine Lance Corporal Jimmy Finley from Louisiana grills steaks at a Forward Operating Base  in Deleran, Afghanistan. Joe Raedle/Getty Images Europe hide caption

itoggle caption Joe Raedle/Getty Images Europe

Om Nom Nom: As we began to shy away from eating primarily fruit, leaves and nuts and began eating meat, our brains grew. We developed the capacity to use tools, so our need for large, sharp teeth and big grinders waned. From left, a cast of teeth from a chimpanzee, Australopithecus afarensis and a modern human. William Kimbel/Institute of Human Origins hide caption

itoggle caption William Kimbel/Institute of Human Origins

The human shoulder (above) allows the arm to hang freely and enables us to flex the arm at the elbow and perform tasks in front of us with ease. Because of its location and structure, the human arm is great for throwing. The ape shoulder (below), by contrast, allows for a different range of motion and is more suited to hanging from trees. Maggie Starbard/NPR hide caption

itoggle caption Maggie Starbard/NPR

A flint-knapper makes sharp stone flakes by striking a flint "core" with a hammerstone. Human Origins Initiative hide caption

itoggle caption Human Origins Initiative

Feet On The Ground: Barefoot runners tend to land on the balls of their feet rather than on their heels the way most shoe-runners do. Rick Roeber went shoeless in 2003 and has clocked more than 13,000 barefoot miles since. Charlie Riedel/AP hide caption

itoggle caption Charlie Riedel/AP

Anthropologist Brian Richmond is trying to determine what the footprints of modern humans can tell us about how we evolved. NPR hide caption

itoggle caption NPR

The Leviathan melvillei attacks a medium-size baleen whale in this artist's rendition. C. Letenneur/MNHN hide caption

itoggle caption C. Letenneur/MNHN

Icebergs float in a bay off Ammassalik Island, Greenland. John McConnico/AP hide caption

itoggle caption John McConnico/AP

A worker drives an electric cart past air monitoring equipment in a storage room of the Waste Isolation Pilot Plant in Carlsbad, N.M. HO/AP hide caption

itoggle caption HO/AP