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

Madagascar is a hot spot of extinctions, and members of the Chamaeleonidae family are currently going extinct. Ignacio De la Riva hide caption

itoggle caption Ignacio De la Riva

The U.S. Department of Energy spends $235 million to run the Waste Isolation Pilot Plant in Carlsbad, N.M. And that investment means jobs. Department of Energy hide caption

itoggle caption Department of Energy

An offshore oil rig is seen in the Catalina Channel near Long Beach, Calif., in 2008. On Monday, Gov. Arnold Schwarzenegger withdrew his support for a controversial new offshore oil drilling project off the Santa Barbara coast. David McNew/Getty Images hide caption

itoggle caption David McNew/Getty Images