A search through decades-old frozen infant stool samples has yielded rich dividends for scientists. They have customized a laboratory technique to screen thousands of samples for norovirus, a major cause of acute gastroenteritis outbreaks in people of all ages. What they discovered about the rate of evolution of a specific group of noroviruses could help researchers develop specific antiviral drugs and, potentially, a vaccine against a disease that is very unpleasant and sometimes deadly.