A prime exponent of evolutionary theory in the late nineteenth century, the British naturalist Alfred Russel Wallace arrived independently at the theory of natural selection nearly simultaneously with Charles Darwin. The numerous publications that emerged from his extended field excusions into the Amazon Basin and the Malay Archipelago (Indonesia) Wallace resulted in major contributions to evolutionary theory, biogeography, ecology, and ethnography, and made Wallace, by the end of his life, one of the best known naturalists in Britain. A Socialist, social progressive, and Spiritualist, Wallace's distinctive take on evolutionary change differed from the Darwinian mainstream in significant ways. The Wallace Collection is a miscellaneous assemblage of letters written by and to Alfred Russel Wallace, primarily during the last twenty five years of his life. Varied in content, the letters touch on Wallace's views on evolution, Spiritualism, and to a less degree, his progressive social commitments.

One of the four horsemen of the evolutionary synthesis of the 1940s, Theodosius Dobzhansky played a crucial role in bridging the gap between theoretical and empirical approaches in genetics and in promoting the Neo-Darwinian synthesis. His contributions to the biological species concept and to an understanding the evolutionary dynamics of wild populations of Drosophila were fundamental to the development of modern population genetics and evolutionary thought. The Dobzhansky Papers are a remnant of the correspondence and writings of the geneticist and evolutionary biologist, Theodosius Dobzhansky. The correspondence (7.5 linear feet) provides insight into Dobzhansky's scientific, philosophical, and social views, particularly during the last decade of his life. Equally valuable are the 54 notebooks (ca.1917-1975) which comprise an almost uninterrupted self-commentary on Dobzhansky's career, replete with typescripts of personal letters and short essays sent to colleagues and friends. The collection also contains two unbound volumes of annotated "reminiscences" from the Columbia Oral History Project, 1962; two bound volumes of papers dedicated to him on his 70th birthday; and 1.5 linear feet of photographs.