"What I'm saying is that culturally we need a much better balance. We need more of a yin and yang between [introverts and extroverts]." - Susan Cain James Duncan Davidson/TED hide caption

itoggle caption James Duncan Davidson/TED

In sighted people, the part of the brain that recognizes faces is linked to the brain's visual system. But in blind people it seems wired to circuits that process sound. Tina Zellmer/Ikon Images/Corbis hide caption

itoggle caption Tina Zellmer/Ikon Images/Corbis

Women who consume eight or more drinks per week are considered excessive drinkers, according to the CDC. Breast cancer, liver disease and heart disease have all been linked to excessive drinking over time. Ann Boyajian/Illustration Works/Corbis hide caption

itoggle caption Ann Boyajian/Illustration Works/Corbis

Bioethicist Peter Singer argues that, under certain circumstances, people should have the right to die at a time of their choosing. Samuel La Hoz/Intelligence Squared U.S. hide caption

itoggle caption Samuel La Hoz/Intelligence Squared U.S.

When beverage companies like Pepsi create ad campaigns with stars like Beyonce, they're trying to appeal to youth, says Jennifer Harris of the Rudd Center for Food Policy & Obesity. Walter McBride/Corbis hide caption

itoggle caption Walter McBride/Corbis

Baby Sesay, a traditional healer in Sierra Leone, treated a child who later died, apparently of Ebola, and then became sick herself and went to a care center. As this photo was taken, her body seized up and she nearly collapsed. David P Gilkey/NPR hide caption

itoggle caption David P Gilkey/NPR