Delegates took their seats during the plenary session at the Bonn climate change conference on March 10, 2014. Negotiations resume this week; by the end of the year, the U.N. hopes to have forged a new global agreement. UNclimatechange/Flickr hide caption

itoggle caption UNclimatechange/Flickr

President Obama is renaming Alaska's Mount McKinley in an effort to strengthen cooperation between the government and Alaska Native tribes. The peak is returning to its traditional name, Denali. Al Grillo/AP hide caption

itoggle caption Al Grillo/AP

Two octopuses going at it — or, as marine biologist Peter Godfrey-Smith might put it, engaging in a bit of "ornery" behavior. Peter Godfrey-Smith (CUNY and University of Sydney), David Scheel (Alaska Pacific University), Stefan Linquist (University of Guelph) and Matthew Lawrence. hide caption

itoggle caption Peter Godfrey-Smith (CUNY and University of Sydney), David Scheel (Alaska Pacific University), Stefan Linquist (University of Guelph) and Matthew Lawrence.

California condors have enormous wingspans. That's fine in the wilderness, but when a bird of this size encounters a power line, the results can be fatal. The San Diego Zoo Safari Park has a program to help train birds to avoid the hazard. Jon Myatt/U.S. Fish and Wildlife Service/Flickr hide caption

itoggle caption Jon Myatt/U.S. Fish and Wildlife Service/Flickr

Neurologist Dr. Oliver Sacks speaks at Columbia University in June 2009 in New York City. Sacks, a prolific author and commentator, has died at age 82. Chris McGrath/Getty Images hide caption

itoggle caption Chris McGrath/Getty Images

Professor Douglas Causey logs information as he tags and takes basic measurements of the birds he harvested in the Aleutian Islands on June 4. He is looking at the birds' blood and their diet, hoping to find out the ways the ocean is changing as it warms. Bob Hallinen/ADN hide caption

itoggle caption Bob Hallinen/ADN

Male and female tungara frogs. Among these frogs, the guy with the best call usually wins the gal — except when you throw a third-choice loser into the mix. Alexander T. Baugh/Encyclopedia of Life hide caption

itoggle caption Alexander T. Baugh/Encyclopedia of Life

Dr. Bill Mahon says a gorgeous coast and the chance to practice a more personal style of community medicine lured him to remote Fort Bragg, Calif., 35 years ago. Farida Jhabvala Romero/KQED hide caption

itoggle caption Farida Jhabvala Romero/KQED

Male treehoppers make their abdomens thrum like tuning forks to transmit very particular vibrating signals that travel down their legs and along leaf stems to other bugs — male and female. Courtesy of Robert Oelman hide caption

itoggle caption Courtesy of Robert Oelman

Heroin sold in the U.S., like this dose confiscated in Alabama last fall, is often cut with other drugs. Tamika Moore/AL.com/Landov hide caption

itoggle caption Tamika Moore/AL.com/Landov

Ah, sugar — we love the sweetness, but not the calories. For more than a century, food technologists have been on a quest for the perfect, guilt-free substitute. The latest candidate, allulose, is not available to consumers in a crystal form: It is a syrup only available to manufacturers. Ryan Kellman/NPR hide caption

itoggle caption Ryan Kellman/NPR