High school athlete Graham Hill, number 50, suffered a concussion in 2013 while playing football at Trinity Christian Academy in Addison, Texas. Courtesy of Jeffrey McWhorter hide caption

itoggle caption Courtesy of Jeffrey McWhorter

Ultrasound is often used for prenatal screening. It's just one of several prenatal screenings available to pregnant women. iStockphoto hide caption

itoggle caption iStockphoto

The UASK app helps sexually assaulted college students in D.C. access a range of services, from rides to the hospital to phone numbers for counselors. The information is personalized to their school. Another version of the app, ASK, provides the same resources to non-students. Emily Jan/NPR hide caption

itoggle caption Emily Jan/NPR

An example of a human precision grip — grasping a first metacarpal from the thumb of a specimen of Australopithecus africanus that's thought to be 2 to 3 million years old. T.L. Kivell & M. Skinner hide caption

itoggle caption T.L. Kivell & M. Skinner

Dr. Stephen Teach helps Jeffery Ulmer listen to his daughter Alauna's asthmatic breathing at Children's National Medical Center in Washington, D.C. Alauna's mother, Farisa, holds her. The District has one of the highest rates of pediatric asthma in the country. Jahi Chikwendiu/Washington Post hide caption

itoggle caption Jahi Chikwendiu/Washington Post

Oh, sugar! If this time of year has you rethinking your diet, there is one surefire change you can make to improve health: Cut back on sugar. Farrukh/Flickr hide caption

itoggle caption Farrukh/Flickr

Biologist Rob Knight, co-founder of the American Gut Project, recently moved the project to the University of California, San Diego's School of Medicine. Casey A. Cass/University of Colorado hide caption

itoggle caption Casey A. Cass/University of Colorado