15 years since a deadly tornado brought Joplin, Mo. together, kindness carries on

In the aftermath of the tornado, thousands of volunteers came to help Joplin from around the country. Many wrote messages of hope on this tornado-damaged house, and later, Joplin residents wrote a thank-you message to the volunteers.

Nearly 100,000 volunteers helped the town rebuild and a spirit of community service continues to this day. Researchers studying human behavior catastrophes can bring out compassion in surprising ways.

(Image credit: FEMA)