Rob Knight, co-founder of the American Gut Project at the University of Colorado in Boulder, works in the lab where the samples are processed. The American Gut Project hide caption

itoggle caption The American Gut Project

The dengue virus has an icosahedral shape, similar to the pattern on a soccer ball. Antibodies stop the virus by binding to its surface. Laguna Design/Science Source hide caption

itoggle caption Laguna Design/Science Source

After a quick swipe and online registration, these test tubes were ready to ship back to the lab at the University of Colorado in Boulder for sequencing and analysis. Katherine Harmon Courage for NPR hide caption

itoggle caption Katherine Harmon Courage for NPR

Making and taking a hit chest to chest, instead of skull to skull, is easier to remember if you're not wearing a helmet, say University of New Hampshire Wildcat football players. Jack Rodolico/New Hampshire Public Radio hide caption

itoggle caption Jack Rodolico/New Hampshire Public Radio

Dental students use practice dummies Aug. 27 in a newly renovated section of Grand Rapids Community College in Grand Rapids, Mich. Health care is one field for which a recent study found that a community college degree produced a strong financial return. Zach Gibson/MLive.com/Landov hide caption

itoggle caption Zach Gibson/MLive.com/Landov

Georgetown's Robert Clark says it's very difficult to say precisely how many experiments have been spoiled by contaminated cell lines. Phil Humnicky/Courtesy of Georgetown University hide caption

itoggle caption Phil Humnicky/Courtesy of Georgetown University

By increasing the amount of serotonin in the spinal cord, an experimental drug helps nerve connections work better. Bee Smith/Ocean/Corbis hide caption

itoggle caption Bee Smith/Ocean/Corbis

An inside view of this fossil Pseudodon shell shows that the hole made by Homo erectus is exactly at the spot where the muscle attached to the shell. Poking at that spot would force the shell open. Henk Caspers/Naturalis Leiden/The Netherlands hide caption

itoggle caption Henk Caspers/Naturalis Leiden/The Netherlands

Rotten, fermented fruit has some nutritional value, and may have looked pretty good to our hungry ancient ancestors. Evolving the ability to metabolize the alcohol in fermented fruit may have helped us adapt to a changing climate 10 million years ago, research suggests. iStockphoto hide caption

itoggle caption iStockphoto

Do you want to go to the park? Mango Doucleff, of San Francisco, responds to her favorite command by perking up her ears and tilting her head. Michaeleen Doucleff/NPR hide caption

itoggle caption Michaeleen Doucleff/NPR