Jennifer Doudna and her colleagues found an enzyme in bacteria that makes editing DNA in animal cells much easier. Cailey Cotner/UC Berkeley hide caption

itoggle caption Cailey Cotner/UC Berkeley

All of our scientific tools have limits. These limits ensure that we will never see the whole picture. We can never have complete knowledge of the universe. Above, the ESO's APEX radio telescope probes the heavens from its lonely perch on Chile's Chajnantor plateau. Gordon Gillet/ESO hide caption

itoggle caption Gordon Gillet/ESO

Fabien Cousteau sits inside Aquarius Reef Base in 2012. If he is able to remain under water for 31 days, he will have lasted one day longer than his grandfather, Jacques Cousteau. Mark Widick/AP hide caption

itoggle caption Mark Widick/AP

Contestants compete in a rock-paper-scissors tournament in Gainesville, Fla., in 2012. A new study indicates it's not as random as it seems. Matt Stamey/Gainesville Sun/Landov hide caption

itoggle caption Matt Stamey/Gainesville Sun/Landov

A worker holds a white rodent at the State Key Laboratory of Biotherapy in Chengdu, China. Researchers at McGill University in Montreal found that mice left alone with a man had increased levels of the hormone corticosterone. China Photos/Getty Images hide caption

itoggle caption China Photos/Getty Images

Made for a tight grip: The female penis of an insect species newly discovered in Brazil has spines on it. Courtesy of Current Biology, Yoshizawa et al. hide caption

itoggle caption Courtesy of Current Biology, Yoshizawa et al.