Nathan Phillips looks at methane data plotted on a map of Boston streets on Nov. 17. Data from a mobile methane "sniffer" and a GPS show a real-time display of the gas levels in Google Earth. The orange spike in the center of the screen, on St. Paul Street, indicates methane levels about two or three times above normal levels, Phillips says. Robin Lubbock/WBUR hide caption

itoggle caption Robin Lubbock/WBUR

The world's population has just hit 7 billion people and continues to grow. Population experts are concerned about the rise in consumption that will accompany the increase in people. One California home builder, ZETA Communities, designs and builds small, highly energy-efficient homes.

Zeta Communities hide caption

itoggle caption Zeta Communities

This abalone shell was found with ocher and a grinding stone. The iron oxide was used as a pigment to paint bodies and walls, as well as to thicken glue.

Science/AAAS hide caption

itoggle caption Science/AAAS

Spooked by a noise, giraffes in northwest Namibia interrupt lunch to look around. John W. Poole/NPR hide caption

itoggle caption John W. Poole/NPR

Cattle and zebra share a meal in a pasture in Kenya. Ryan Lee Sensenig/Science hide caption

itoggle caption Ryan Lee Sensenig/Science

The Quay Brothers, filming Through The Weeping Glass at the Mutter Museum in Philadelphia. The Quays started filming without a script or a storyline. Edward Waisnis/Behind the Scenes with the Quay Brothers hide caption

itoggle caption Edward Waisnis/Behind the Scenes with the Quay Brothers

When the T. rex skeleton was first put on display, it was presented standing vertically, in this Godzilla-like pose, as seen at the Carnegie Museum of Natural History around 1950. Recent studies show the dinosaur actually kept its body horizontal. Watch the videos here to see how T. rex walked. Carnegie Museum of Natural History hide caption

itoggle caption Carnegie Museum of Natural History

The fossil of Australopithecus sediba could be the long-sought transition between ape-like ancestors and the first humans. "It shows a small brain, but a brain that's beginning to reorganize in some ways that resemble our brain," says anthropologist Lee Berger. Brett Eloff via Lee Berger/University of Witwatersrand hide caption

itoggle caption Brett Eloff via Lee Berger/University of Witwatersrand

An artist's reconstruction of the Tibetan woolly rhino. Woolly rhinos used their flattened horns to sweep snow off of vegetation, a critical adaptation to survive frigid conditions. Image by Julie Naylor hide caption

itoggle caption Image by Julie Naylor