Stern, Curt, 1902-1981

Geneticist and professor at the University of California, Berkeley.

Curt Stern was a geneticist.

In the generation of great Drosophila geneticists that came of scientific age in the 1920s, Curt Stern stood out as one of the most original and most productive thinkers. A scientist who combined an exacting intellect with sterling abilities as an educator, writer, and interpreter of his field, Stern began life in the blazing days of the rediscovery of Mendel's laws and ended as molecular and biochemical techniques transformed his discipline. His career, in many ways, is a microcosm of the development of genetics in the 20th century.

Raised in the vicinity of Hamburg, Germany, by an English father and German mother, Stern saw a childhood interest in animals become a career when he enrolled in Max Hartmann's zoology course at the University of Berlin. Continuing under Hartmann for his graduate studies, Stern earned a doctorate in 1923 at the tender age of 21 for a cytological study of mitosis in the heliozoa, and that same year he became one of the first recipients of a new program of international fellowships funded by the Rockefeller Foundation.

Thus in 1924 Stern arrived in New York to begin work in T. H. Morgan's famed fly room at Columbia University. Leaping into Drosophila with zeal, Stern busied himself with a study of a sex-linked recessive gene that produced shortened ("bobbed") bristles. Discovering that XXY females did not express the bobbed mutation, Stern hypothesized that the Y chromosome (ordinarily found only in males) carried the wild type dominant allele, providing evidence for the first time that the Y chromosome did indeed contain genetic information. Stern subsequently explored the implications of Y-chromosome fragmentation for fertility, and when he returned to Germany in 1926 to take up a position as Richard Goldschmidt's assistant in the Kaiser Wilhelm Institut, he stood on the threshold of another major discovery in genetics.

Along with the near-simultaneous work of Harriet Creighton and Barbara McClintock on maize, Stern's research on Y-chromosome fragmentation confirmed beyond all reasonable doubt the chromosome theory of heredity as well as the physical exchange of segments between homologous chromosomes by crossing over. This co-discovery was a milestone in the development of genetic theory and made Stern's name familiar throughout the field. His subsequent research on Drosophila continued to produce path-breaking results, including one of the earliest demonstrations of gene dosage effects, of genetic compensation in development, and of somatic crossing over.

At Kaiser Wilhelm, Stern also emerged as a significant figure in synthesizing ideas about his discipline, turning his attention to a review of the establishment of the chromosome theory of heredity, to the interaction of multiple alleles in animal populations ( Multiple Allelie, 1930), and to an examination of linkage and crossing over ( Faktorenkoppelung und Faktorenaustausch, 1933), the area to which Stern had personally contributed so substantially. Attending the Sixth International Congress of Genetics at Cornell in 1932, he found himself one of the international guiding lights in genetic research. That summer, he married the American, Evelyn Sommerfield.

The rise to power of the Nazi Party in 1933 dramatically altered the course of Stern's life. After he had arranged a six-month appointment at Cal Tech, Stern secured an appointment at the University of Rochester, wisely opting not to return to Germany. Despite his credentials, he did not become a full professor at Rochester until 1941. He never again returned to Germany. The conditions of his emigration, however, did nothing to diminish Stern's productivity. He continued his Drosophila research with vigor throughout the 1930s, examining the interaction of development and chromosomal arrangement on genetic expression, among other subjects.

During the war, Stern channeled some of his time into new pursuits. Contributing to the war effort, he became one of the heads of the genetic studies conducted at Rochester under the auspices of the Manhattan Engineering District, examining the effects of radiation on mutation rate, gene expression, and physiology. His findings, that even low doses can produce measurable rates of mutations that can be linearly extrapolated from the rates produced at higher doses, eventually, led to more stringent protection for nuclear workers. He later served on the Advisory Committee for Biology and Medicine of the Atomic Energy Commission from 1950 to 1955, and remained interested in radiation biology for much of the rest of his career.

Paradoxically, Stern also developed an increasing interest in the dimly viewed field of human genetics during the war, in part through teaching students enrolled in the ASTP premedical program at Rochester, and perhaps in conjunction with the changing research interests of James V. Neel, who had been Stern's first graduate student. In 1947, when Stern left Rochester to replace Richard Goldschmidt in the Department of Zoology at the University of California, he was deeply engaged in research into the population dynamics of Rh blood incompatibility between Rh-negative mothers and their Rh-positive offspring. Equally important, he published a seminal textbook on human genetics, the Principles of Human Genetics, that for many years and through three editions was the standard in the field.

An excellent lecturer, punctilious writer, and exacting thinker, Stern's career at Berkeley is reflective of many of the changes affecting American science in the post-war period. Always in great demand, Stern was forced to limit his commitments outside of Berkeley and refused all prospective graduate students in human genetics in favor of those devoted strictly to Drosophila . Particularly as he grew toward the end of his career, Stern began to take a more retrospective view of his field, writing on the rediscovery of Mendel's theory and other aspects of the history of genetics and turning to consideration of the social and philosophical implications.

Stern was recipient of numerous honors and awards during his career, including election to the American Philosophical Society (1954) and the National Academy of Sciences. He was twice recipient of a Guggenheim Fellowship (1955, 1963), received the Kimber Aware in Genetics from the National Academy of Sciences, and was president of both the Genetics Society of American and the Social for Human Genetics. He died in Berkeley in 1981.

Papers of James V. Neel, pioneering human population geneticist and professor in the Department of Human Genetics, University of Michigan Medical School. Curt Stern's first graduate student at the University of Rochester, and a post-doctoral student under Theodosius Dobzhansky, Neel began his career as a Drosophila geneticist, but after taking his first professional appointment as an assistant professor at Dartmouth, decided to alter his course into human genetics. Reasoning that he needed a solid medical education to complement his genetical training, he returned to Rochester in 1942 to study for an MD.

Like all medical students during the Second World War, Neel was inducted into military service. Rochester was the base for studies in radiation biology associated with the Manhattan Project, and at the end of the war, with Neel still in the military, a chance friendship with the adjutant to the head of the project resulted in Neel's appointment to help organize a genetical survey of the atomic bomb survivors. In 1946-1947, Neel lived in Hiroshima, organizing this project, part of the Atomic Bomb Casualty Committee (ABCC), and he maintained a close connection to the study until his death. His work in Japan mushroomed, too, into a series of related projects into the biology and genetics of consanguinity, among other topics.

While at Rochester, Neel also began to establish a name for himself in other areas of human genetics. As a resident at Rochester's Strong Memorial Hospital, Neel encountered a case of thalassemia, and reading the medical literature, he became convinced that it was a genetic recessive disease. Over a span of five years, he delineated the genetic basis of haemoglobin diseases - first thalassemia, then sickle cell disease - in the process, helping to precipitate the revolution in biochemical genetics of the 1950s through 1970s. Neel's work also encompassed the evolutionary implications for these diseases, implanting balanced polymorphism and heterozygote advantage into the vocabularies of evolutionary biologists. Neel's studies of thalassemia and sickle cell disease were recognized with the receipt of the Lasker Award in 1955.

In the late 1950s, Neel entered into a third major set of projects, turning to extensive field studies in population genetics. Recognizing that the number of human populations isolated from modern medicines and modern technology was rapidly dwindling, Neel embarked on an ambitious genetic survey of the comparatively "primitive" Xavante of Brazil and, later, the Yanomamo of the Brazilian-Venezuelan borderlands. These studies, carried out over the course of more than a decade, and involving even longer spans of laboratory work, constitute the first and most comprehensive studies of human population and breeding structure and genetic diseases among "primitive" peoples. Dr. Neel died in February, 2000.