Uzuri Pease-Greene, right, leads a walk through the public housing complex in the Potrero Hill neighborhood of San Francisco where her family lives. She is working to have the old buildings replaced. Talia Herman for NPR hide caption

itoggle caption Talia Herman for NPR

Greg O'Brien gathers his thoughts before a run in 2013. "Running is essential," he says. Michael Strong/Living With Alzheimers hide caption

itoggle caption Michael Strong/Living With Alzheimers

Closing loopholes in background checks for gun purchases would reduce the risk of death and injury, doctors' and attorneys' groups say. Alexa Miller/Getty Images hide caption

itoggle caption Alexa Miller/Getty Images

Most parents have a favorite child, psychologists say, even if they try to be fair. Hero Images Inc./Corbis hide caption

itoggle caption Hero Images Inc./Corbis

Mamuedeh Kanneh was married to Laiye Barwor, the man who brought Ebola to Barkedu, Liberia. He died of the virus. She now cares for her children as well as children who lost their parents to the disease. John W. Poole/NPR hide caption

itoggle caption John W. Poole/NPR

"Although we human adults are really good at understanding other minds, we weren't always that way." - Rebecca Saxe James Duncan Davidson/TED hide caption

itoggle caption James Duncan Davidson/TED

"Once I awoke...I could not walk, talk, read, write; I could not recall any of the details of my life. Jill Bolte-Taylor died that day." - Jill Bolte-Taylor Andrew Heavens/TED hide caption

itoggle caption Andrew Heavens/TED

"Human cognitive science and cognitive neuroscience are starting to give us an answer to...who we are as thinkers." - Nancy Kanwisher James Duncan Davidson/TED hide caption

itoggle caption James Duncan Davidson/TED

The size of the brain of a chimpanzee (right) is considerably smaller than that of a human brain. Probably multiple stretches of DNA help determine that, geneticists say. Science Photo Library/Corbis hide caption

itoggle caption Science Photo Library/Corbis

People who practice free-range parenting say it makes kids more independent, but others see it as neglect. State and local laws don't specify what children are allowed to do on their own. iStockphoto hide caption

itoggle caption iStockphoto

Residents of ShantiNiketan, a retirement community near Orlando, Fla., walk in a Hindu religious procession. Courtesy of ShantiNiketan Inc. hide caption

itoggle caption Courtesy of ShantiNiketan Inc.

If 13 episodes in a row with Piper and Crazy Eyes sounds like your dream day, social scientists want to talk with you about your habits. Paul Schiraldi/NetFlix/AP hide caption

itoggle caption Paul Schiraldi/NetFlix/AP