Tilly Edinger (1897-1967) was born Johanna Gabrielle Ottelie Edinger and is recognized as a pioneer in the field of paleoneurology, which is the study of the brain through fossil remains. Her major work is titled Evolution of the Horse Brain.

Edinger applied her knowledge of neurology to the study of paleontology to determine how the brains of a species evolved. Because brains decompose, she focused on the study of the fossilized remains of the skulls and cranial cavities of many species to hypothesize that brains of any given species evolve differently based upon immediate external stimuli. Rejecting previous scientific notions from the eighteenth- and nineteenth-centuries, which asserted that evolution was a linear progression resulting in such lower animals as rodents eventually evolving into higher beings such as humans, Edinger postulated that evolution follows a complex branching process. This is a process by which different environmental factors that include climate and weather cause a species to evolve in radically different ways. In Evolution of the Horse Brain, Edinger proposed that the rate of evolution varies according to the individual lineage of any member of a particular species, and it is based upon that individual's ability to adapt, as well as the capacity of the brain's components to evolve new methods of interaction.

Edinger was born on November 13, 1897, in Frankfurt, Germany. Her Jewish parents were members of Germany's upper class, and they provided her with a financially secure childhood in her hometown of Frankfurt am Main. The ready availability of money provided Edinger and her two older siblings with ample educational, travel, and leisure opportunities. Her father, Ludwig E. Edinger, was a professor of neurology at the University of Frankfurt, a respected researcher, and one of the founders of comparative neurology. He was held in such high esteem that the city of Frankfurt am Main named a street after him following his death in 1918. Edinger's mother, Anna Goldschmidt Edinger, was a descendent of the Warburg family of bankers. Her active engagements in charity and social work resulted in the city honoring her with a bronze bust in the municipal park.

Edinger attended several universities, including schools in Heidelberg and Munich, before graduating from the Schillerschule in Frankfurt am Main. She had originally intended to study geology because she was convinced it would be easier for a woman to obtain a position in the field of zoology. Her focus was vertebrate paleontology. Edinger received her doctorate in natural philosophy from the University of Frankfurt in 1921, after her dissertation on the cranial capacity of the extinct Triassic era marine reptile Nothosaurus was accepted. Following her doctorate, Edinger pursued her interest in neurology and paleontology as a research assistant at the University of Frankfurt until 1927. Financially independent because of her family's wealth, she accepted an unpaid position in 1927 as curator of the vertebrate collection at Frankfurt's Senckenberg Museum. After publication of her first major work, Die fossilen gehirne (Fossil Brains) in 1929, the museum offered her a paid position.

When the Nazi party took political control of Germany in 1933, Edinger chose to remain in Frankfurt am Main. While her supervisor at the Senckenberg Museum was a member of the Nazi party, he allowed Edinger to continue her work as museum curator. In return, the supervisor requested that Edinger remove her name from her office door and vacate the building whenever there was a Nazi visitor. She worked under these circumstances until 1938, when the Nazi party increased its pressure on the German Jewish community. She applied for an exit visa in order to immigrate to the United States in 1938 but was placed on a waiting list. In May 1939, she was granted temporary permission to leave Germany. Her brother Friedrich (Fritz), however, was less fortunate and perished in the Holocaust. In addition, the Nazis removed the statue of Edinger's mother from the municipal park and changed the name of the street bearing her father's name. Edinger settled in London and worked as a wartime translator of medical texts. In 1941, she immigrated to the United States and accepted a tenured faculty appointment at Harvard University. Alfred Sherwood Romer, director of Harvard's Museum of Comparative Zoology, appointed Edinger to the position of research assistant at the museum. With the exception of one year of teaching at Wellesley College, she retained her position at the museum until 1966.

Published in 1929, Edinger's Die fossilen gehirne is considered her first major study. In this book, she argued persuasively that scientists should study fossils in order to determine the evolution of a specie's brain. This method was in opposition to the prevailing scientific method of the previous 150 years, in which scientists used the skulls and brains of contemporaneous animals to explain the evolution of its species. Edinger argued that such a method resulted in erroneous conclusions, because each generation of species possessed its own identifying creatures incumbent upon the climate, environment, and other determining factors specific to that generation. She argued that these factors directly led to brain development changes that were unique to that generation. To prove her theory, Edinger pioneered the method of using plaster casts of the fossilized remains of animal skulls and cranial cavities. Once the cast is made, scientists can make educated guesses on the size and shape of the different components of the animal's brain and how those components interact. Once these determinations were made, they could be compared to previous or subsequent generations of fossil remains.

Her second major work, The Evolution of the Horse Brain continued her explorations into the evolution of mammalian brains. In this work, she presented a convincing argument for the independent development of an enlarged forebrain in several species of mammal, focusing on the horse as an example. She argued that previous assumptions of linear evolution could not account for such a widespread occurrence among so many different species. She thus was able to explain how animals, including humans, developed at different rates in varying geographical locations and in different time periods based upon the lineage of the species member and the physical demands placed upon it by that location's climate and environment.

In 1950, Edinger received a fellowship from the American Association of University Women to study fossils. Her research took her to five countries in western Europe and produced several papers on her findings. She continued her studies with the help of a Guggenheim Fellowship. In 1963, her membership in the American Academy of Arts and Sciences led to her election as the president of the Society of Vertebrate Paleontology. She later earned honorary doctorates from Wellesley College and the German universities in Giessen and Frankfurt am Main. On May 26, 1967, prior to an anticipated return visit to Frankfurt, Edinger received serious injuries while walking near her home in Cambridge. Suffering a serious hearing impairment since birth that also increasingly prevented her from teaching, she did not hear the approaching automobile that eventually struck her. She died the following day.

Further Reading

• Kass-Simon, G., and P. Farnes, Women of Science: Righting the Record, Indiana University Press, 1990.
• Notable Twentieth-Century Scientists, Gale Group, 1995.
• Notable Women Scientists, Gale Group, 2000.
• Sicherman, B., and C. H. Green, editors, Notable American Women: The Modern Period, Harvard University Press, 1980.
• Women in World History: A Biographical Encyclopedia, Yorkin Publications/Gale Group, 2000.
• Society of Vertebrate Paleontology News Bulletin, no. 81, 1967.