The mid-nineteenth century marked a period of significant advancement in understanding human biology. Two developments were later appropriated by scientists in developing theories of genetic heritability—Charles Darwin's publication of The Origin of Species (1859), which provided a theory of evolution that became the basis for understanding racial diversity, and Gregor Johann Mendel's experimental work on heredity in plants.
Mendel's account of the experiments and his conclusions, published in 1866, were largely ignored during his lifetime, but were rediscovered in 1900, and became the basic tenets of genetics. In The Descent of Man (1871), Charles Darwin discussed the origins of race, and noted naturalists' great difficulty in determining an exact number of "races." Darwin, a monogenist on the question of race, believed that all humans were of the same species and found "race" to be a somewhat arbitrary distinction between groups.
Southern doctors Samuel Cartwright, Josiah Clark Nott and James Marion Sims were among the race scientists who gained prominence in the scientific community in the 1850s by legitimizing the exploitation of slaves. Scientific experiments on blacks were routine, a practice that continued in medical and research fields well beyond slavery. In the years after the Civil War, southern physicians published scientific studies which sought to prove that blacks were dying out as a race under the conditions of freedom, implying that the system of slavery had been beneficial.
In 1851, Louisiana plantation doctor Samuel Cartwright tried to explain the tendency of black slaves to flee captivity by proposing a psychiatric diagnosis that he called "drapetomania." The term was derived from the Greek drapetes, or runaway, and mania, or madness. Cartwright suggested in New Orleans Medical and Surgical Journal that slave owners could treat and cure this “medical disorder” by whipping slaves and amputating their toes.
J. Marion Sims, considered the "father of American gynecology," moved to Alabama from Philadelphia after his first two patients died. There, Sims developed a technique to repair a condition in women called vesicovaginal fistula, which was usually the result of traumatic labor. This new technique to repair the condition became the standard procedure. He also devised instruments, including the Sims' speculum, to perform the surgery. In 1852, his technique using silver sutures led to the successful repair of fistulas, but he operated on his slave subjects, Anarcha, Betsy, and Lucy, approximately 40 times without the use of anesthesia, despite the fact that it was widely available.
Paul Broca, a French pathologist, anthropologist and pioneer in neurosurgery, was a founder of the Anthropological Society of Paris (1859) and the Revue d'anthropologie (1872). He identified the brain area for articulate speech, which became known as Broca's area, and developed methods of classifying hair and skin color. He established brain and skull ratios—cranial anthropometry—and even created instruments used in measuring and calculating indices such as craniometers. Using anthropometric methods, Broca devised a Eurocentric classification that purported to establish a relationship between anatomical features of the brain and mental capabilities.
Sir Francis Galton, a British anthropologist, pioneered the field of eugenics, which sought to improve and control human hereditary traits. Especially intrigued by Charles Darwin’s work, The Origin of Species, Galton devoted much of his life to exploring its implications. He devised techniques such as composite photography in order to establish racial and social "types." He was a proponent of selective human breeding to halt what he saw as the decline of the British race. His advocacy of selective breeding was influential in the development of eugenics—a term Galton coined—in the U.S. and later adopted by the Nazi party. He published Hereditary Genius (1869) in which he asserted that talent is an inherited characteristic and established a system of classifying fingerprints that is still used today. In 1883, Galton wrote Inquiries into Human Faculty.