Shown a realistic human target — not just a silhouette like this one — shooters were more likely to pull the trigger if the target was black, according to an analysis of 42 studies. "Even if you think that you're not prejudiced," says researcher Yara Mekawi, "that doesn't necessarily mean that that's true in terms of split-second decisions that you might make in the real world." Joshua Lott/Getty Images hide caption

itoggle caption Joshua Lott/Getty Images

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

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

Michael Arnott, of Cambridge, Mass., says he used to have trouble staying awake on long drives. Sleep specialists discovered he has obstructive sleep apnea, though not for the most common reasons — he isn't overweight, and doesn't smoke or take sedatives. M. Scott Brauer for NPR hide caption

itoggle caption M. Scott Brauer for NPR
Katherine Streeter for NPR

Bacillus subtilis may look like pasta under the microscope, but the bacteria are common in the gut of humans. Could the microbes be contributing to our belly fat? Too soon to tell, scientists say. BSIP/UIG via Getty Images hide caption

itoggle caption BSIP/UIG via Getty Images

African forest elephants stampede in the Central African Republic jungle. Courtesy of Cornell Lab or Ornithology hide caption

itoggle caption Courtesy of Cornell Lab or Ornithology

A daily pill called Addyi is the first medicine to be approved for the purpose of boosting women's sexual desire. Allen G. Breed/AP hide caption

itoggle caption Allen G. Breed/AP

Daniel Craig plays James Bond in the film Casino Royale. Dramatis, a computer program, can detect suspense from this scene and rates it even higher as the plot thickens. MGM/United Artists/Sony/The Kobal Collection hide caption

itoggle caption MGM/United Artists/Sony/The Kobal Collection

Can playing the Project Evo game really improve the brain's ability to deal with distractions? Its manufacturer thinks so. Courtesy of Akili hide caption

itoggle caption Courtesy of Akili

Dr. Claire Guest, co-founder of Medical Detection Dogs, says one of her dogs sniffed out her own breast cancer. Janine Warwick hide caption

itoggle caption Janine Warwick

There are now 15 known convex pentagons, or nonregular pentagons with the angles pointing outward, that can "tile the plane." EdPeggJr/Wikimedia Commons hide caption

itoggle caption EdPeggJr/Wikimedia Commons

This genetically modified yeast can convert sugar into powerful opioid drugs. Scientists working with the modified yeast strains are required to register them with the Drug Enforcement Administration and keep the yeast under lock and key. Courtesy of Christina Smolke/Stanford University hide caption

itoggle caption Courtesy of Christina Smolke/Stanford University

Dyha Gresham (front, left), her older sister Briceshanay (in back) and Briceshanay's daughter Uri stand in their New Orleans home with the family's cat Sugar-Pepper and dog Selena. After Katrina, Briceshanay says, she relied on theater and the arts to help her "move through terrible and difficult times." Edmund D. Fountain for NPR hide caption

itoggle caption Edmund D. Fountain for NPR