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

itoggle caption Courtesy of McMaster University

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

itoggle caption Laura Crossey/University of New Mexico

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

itoggle caption Ye Group and Baxley/JILA

Kepler-22b, seen in this artist's rendering, is a planet a bit larger than Earth that orbits in the habitable zone of its star. Some researchers think there might be "superhabitable" worlds that may not resemble Earth. NASA/Ames/JPL-Caltech hide caption

itoggle caption NASA/Ames/JPL-Caltech

A reproduction of the mural from a room in Catalhoyuk, a Neolithic settlement in Turkey. Sarah Murray/Flickr hide caption

itoggle caption Sarah Murray/Flickr

Vera Wojtesta was one of 300 babies flagged by New York's newborn screening program as at risk of having life-threatening Krabbe disease. Ben Shutts/Courtesy of the Wojtesta family hide caption

itoggle caption Ben Shutts/Courtesy of the Wojtesta family

Zachary Phillips sets up the gigapixel camera at a nature reserve in Virginia. Morgan Walker/NPR hide caption

itoggle caption Morgan Walker/NPR

The plate on the left contains about equal numbers of colonies of two different bacteria. After the bacteria compete and evolve, the lighter ones have taken the lead in the plate on the right. Courtesy of Michael Wiser hide caption

itoggle caption Courtesy of Michael Wiser

A dog burial in Greene County, Ill. This fossil dates back to about 8,500 years ago. Courtesy of Del Baston, Center for American Archaeology hide caption

itoggle caption Courtesy of Del Baston, Center for American Archaeology

This is an artist's illustration of Kepler-62f, a planet in the "habitable zone" of a star that is slightly smaller and cooler than ours. Kepler-62f is roughly 40 percent larger than Earth. NASA/JPL-Caltech/T. Pyle hide caption

itoggle caption NASA/JPL-Caltech/T. Pyle

Friend Or Foe? Scientists say dogs react differently to the direction of another dog's tail wag. Time & Life Pictures/Getty Images hide caption

itoggle caption Time & Life Pictures/Getty Images

The botulism toxin comes from Clostridium botulinum bacteria, seen here in a colorized micrograph. James Cavallini/Science Source hide caption

itoggle caption James Cavallini/Science Source