Beginning in the 20th century, scientific research came to be dominated by a growing class of credentialed, professional scientists who overwhelmingly displaced the learned amateurs of an earlier time. By the end of the century, however, the exclusive realm of professional scientists conducting research was joined, to a degree, by “citizen scientists.” The term originally encompassed non-professionals assisting professional scientists by contributing observations and measurements to ongoing research enterprises. These collaborations were especially common in the environmental sciences, where citizen scientists (...) participated in counting wildlife and measuring environmental conditions. Later, patient groups began to play a more active role in supporting clinical trials and collecting health records from affected individuals. (shrink)