An early and influential advocate for the importation of statistics into biological analysis, Raymond Pearl was a pioneer in American population biology and ecology. The son of Frank Pearl, a grocery clerk and shoe factory foreman, and Ida May McDuffee, Pearl attended Dartmouth College (A.B., 1899) and the University of Michigan (Ph.D., 1902). Like many students of his generation, Pearl traveled abroad after receiving his doctorate to strengthen his education, studying first at the University of Leipzig in 1905, and then under Karl Pearson at University College London (1905-1906). It was Pearson who quickened Pearl's interests in quantitative analysis and fostered his first efforts to apply statistics to population genetics. He married Maud Mary Dewitt, a fellow student at Michigan, and long his collaborator, in 1903.

Pearl's first academic appointments upon returning to the States were as an instructor of zoology at the University of Pennsylvania (1906-1907) and as chair of the Department of Biology at the Maine Agricultural Experiment Station (1907-1918). Befitting his position in Maine, Pearl was engaged primarily in applied research in the genetics of poultry and cattle. Through studies aimed at increasing the productivity of egg-laying in chickens, he turned from an analysis of the inheritance of individual traits to patterns of inheritance in populations. Recognizing, as Mendelian theory predicted, that individuals often did not express the same traits as their parents, Pearl began to study population-level characteristics such as birth rate, death rate, and population size, and to reconceptualize the genetic and environmental dynamics of evolutionary change. His work took him variously into a reanalysis of Malthus' predictions on population density and into direct conflict with the tendencies of much eugenic research to focus on individual traits and individual couples. By 1915, his reputation had grown widely enough in scientific circles to merit election to the American Philosophical Society and, in 1916, to the National Academy of Sciences.

Leaving Maine to become Professor of Biometry at Johns Hopkins in 1918, Pearl entered into the most productive period of his career. At Hopkins, where he served variously as Professor of Biology (1923-1940) and as statistician at the Johns Hopkins Hospital (1919-1935), Pearl turned a statistical eye toward the dynamics of human populations, producing remarkably accurate and durable estimates of changes in world population based upon the best-guess estimates for birth rate and longevity. More controversially, based upon U.S. Census data from 1920, he and Lowell J. Reed theorized that the logistic (sigmoidal) curve was in effect a law of nature describing population growth: after a slow initial period of expansion, populations enter a phase of exponential growth until the they reach the carrying capacity of the environment and level off. Although recognized as a useful heuristic for exploring population dynamics, Pearl's aggressive promotion of the logistic curve and his truculence in its defence alienated many of his colleagues. In other research, Pearl experimented with the factors influencing population dynamics in Drosophila melanogaster, turned to estimates of life expectancy based upon occupation and personal habits, and entered into various statistical aspects of reproductive behavior. An inveterate opponent of most eugenic policies, and critic of eugenic research, he was nevertheless a strong and vocal supporter of birth control and population planning.

Using funds provided by the Rockefeller Foundation, Pearl established the Institute for Biological Research at Johns Hopkins in 1925, heading it throughout its five year existence. He was also active in numerous professional organizations, serving as president of the International Union for Scientific Investigation of Population Problems (1928-1931), the American Association of Physical Anthropologists (1934-1936), and the American Statistical Association (1939),and helping to found and edit the Quarterly Review of Biology in 1926 and Human Biology in 1929. An agile and prolific writer, Pearl wrote 17 books and nearly 700 articles during his career on a extraordinary range of subjects.

This note is currently under review for revision.

A major resource for study of American biometry in the first half of the 20th century, the Pearl Papers contain 14 linear feet of the professional correspondence of Raymond Pearl, longtime professor at Johns Hopkins University, 1.5 linear feet of correspondence with his mother, and one linear foot of letters from Pearl to his wife Maud, concentrated in the period before their marriage, 1897-1899. The Pearl Papers are a rich resource for study of the development of population genetics and population biology during the 1920s and 1930s, as well as biological statistics and biometry, and they contain valuable information on both eugenics and birth control.

The collection is divided into six series:

This note is currently under review for revision.

Arrangement is for the Reader Copies and Approved for Reader Use materials.

Restrictions

Correspondence from H.L. Mencken may not be consulted without permission of Mencken's estate.

Provenance

Majority of papers acquired, 1973. Some family correspondence donated by Raymond Pearl's granddaughter, Penelope Jencks, sculptor and daughter of Ruth DeWitt Pearl Jencks, 2012 (Accession M2012-13).

Preferred citation

Cite as: Raymond Pearl Papers, American Philosophical Society.

Other finding aids

The printed version of Bentley Glass' A Guide to the Genetics Collections of the American Philosophical Society contains another biography of Pearl and a further description of the Pearl Papers.

Separated material

Photographs are housed with graphic materials.

Related material

A significant quantity of Pearl correspondence appears in the papers of Charles B. Davenport (239 items) and Herbert Spencer Jennings (278 items).

Bibliography

African American History Note

Pearl's opposition to eugenics earned him both friends and adversaries (most notable among the latter, E. M. East), as reflected throughout the Pearl papers. His correspondence with East, Herbert Spencer Jennings, Karl Pearson, the National Association for the Advancement of Colored People, Ira Jewell Williams, Edwin B. Wilson, F. A. E. Crew, the Rockefeller Institute, and William T. Howard (among others) touches frequently on issues of genetics, eugenics, race, and human evolution. The correspondence with the N.A.A.C.P. comprises three folders of materials for the years 1927-1936, primarily concerning a study of Harlem Hospital.

This note is currently under review for revision.

Physiology, Biochemistry, and Biophysics Note

Scholars of physiology, biochemistry, or biophysics may find the following items of interest:

Genetics Note

This collection contains materials which relate to the history of genetics.

• American Association of Physical Anthropologists
• Baltimore Sun
• Birth Control Federation of America
• Dartmouth College
• International Statistical Institute.
• National Academy of Sciences (U.S.)
• The Quarterly Review of Biology

• Diaries.

• Bell, James F.
• Berkson, Joseph, 1899-1982
• Bernard, Léon, b. 1877
• Campbell, James A.
• Cox, Eugene A.
• East, Edward M. (Edward Murray), 1879-1938
• Embree, Edwin R. (Edwin Rogers), 1883-1950
• Fisher, Arne
• Gini, Corrado, 1884-
• Greenwood, Major, 1880-
• Harrison, Ross G. (Ross Granville), 1870-1959
• Jones, Bassett, 1877-1960
• Mallet, Bernard, Sir
• Mencken, H. L. (Henry Louis), 1880-1956
• Morgan, Thomas Hunt, 1866-1945
• Pearl, Ida May McDuffee
• Pearl, Maud Mary DeWitt
• Pearl, Raymond, 1879-1940
• Pearson, Karl, 1857-1936
• Ritter, William Emerson, 1856-1944
• Russell, E. S. (Edward Stuart), 1887-1954
• Sanger, Margaret, 1879-1966
• Stefansson, Vilhjalmur, 1879-1962
• Sweeney, James Shirley, 1896-
• Thomas, Charles C., 1925-
• Walcott, Frederic Collin, 1869-1949
• Wheeler, William Morton, 1865-1937
• Willcox, Walter Francis, 1861-1964
• Wilson, Edwin Bidwell, 1879-1964
• Yerkes, Robert Mearns, 1876-1956
• Yule, G. Udny (George Udny), 1871-1951

• Biology
• Biology -- Periodicals
• Biology publishing
• Biology, genetics, eugenics
• Biometry
• Birth control.
• Culture, community, organizations
• Eugenics
• Evolution (Biology)
• Genetics
• Human evolution
• Population biology
• Race, race relations, racism
• Science publishing.
• Social conditions, social advocacy, social reform
• Statistics
• World War, 1914-1918