Raymond Pearl (1879-1940), US biologist and author. Pearl studied at Dartmouth College and the University of Michigan. He worked on biometry, later moving into the field of Mendelian genetics. He is considered one of the founders of biogerontology, the study of the ageing processes. He also published widely as a populariser of science and also worked on science journals. In 1926, he founded The Quarterly Review of Biology. This photograph dates from between 1905 and 1945. It is from the Harris and Ewing Collection, which mostly consists of photographs taken in Washington DC, USA.