Welcome to the Genome. Michael Yudell
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of heredity. Thus, there could be no map of the sequence of this genome, as neither science nor technology was even close to accomplishing this feat. Instead, Morgan began to map the location, or linear arrangement, of particular genes along Drosophila chromosomes. Working with a series of mutations, including variations in body color and wing shape, Morgan and his collaborators were able to create chromosome maps showing the location of certain genes on each of Drosophila’s four chromosomes. (39) Morgan’s group, for example, determined that the white‐eyed mutation lies on the X, or Drosophila sex chromosome. (40)
The beauty of Morgan’s work, much like Mendel before him, stemmed from his powers of deduction. Morgan could never actually see the positions of genes on the Drosophila chromosomes, but he could create virtual maps based on his experiments and deductions. Faced with unknown and unpredictable challenges neither he nor his colleagues on the genetic frontier could have anticipated, Morgan’s team was able to organize information in a fashion that is as elegant and relevant today as it was when his discoveries were made. Morgan’s biographer Garland Allen notes that “there have been few research groups in modern biology that have functioned as effectively together as did Morgan’s group in their fly room between 1910 and 1915.” (41) To develop chromosome maps, the Morgan lab used a technique that came to be known as the three‐point cross. Morgan reasoned that two genes very close to each other on a chromosome would appear to stay with each other even when other parts of the chromosome recombined. By looking at thousands and thousands of flies for visible mutations and breedings these mutations in the lab, Morgan was not only able to arrange these into linkage groups on chromosomes based on whether or not they segregated together, but also to say how the traits were organized on the chromosomes. (42)
But all was not well on the genetic frontier. These new and very powerful ideas concerning heredity, just beginning to make sense to some and still unknown to most, became a way to understand the world not only scientifically, but also socially.
EUGENICS—“PREVAILING SPEEDILY OVER THE LESS SUITABLE”
Morgan was not alone in his search for the mechanisms of heredity. The meanings of heredity captured the attention of natural and social scientists and, of course, the general public. While the work of Morgan and his colleagues dominated the scientific understanding of heredity during the first three decades of the twentieth century, a group of men and women known as eugenicists dominated the public understanding of heredity. These eugenicists, working under the assumption that all traits were heritable and genetic, burst onto the scene beginning in the 1890s, inspired by the work of Francis Galton in England. (43) Galton, a first cousin of Charles Darwin, defined the practice of eugenics as the science of giving “the more suitable races or strains of blood a better chance of prevailing speedily over the less suitable.” (44)
Figure 1.6 Morgan’s experiments with Drosophila led to the development of the first map of an organism’s genes. This modified map shows the location of some genes on the Drosophila X chromosome.
Credit: DNA Learning Center, Cold Spring Harbor Laboratory
The early twentieth century was a turbulent time in world history, particularly in the United States, when an influx of immigrants from Europe and the migration of African Americans out of the Deep South were challenging America’s cultural and racial hierarchy. (45) Discoveries in genetics were seized on to aid in the development of social theories concerning human difference. This ultimately gave rise to eugenics, the science of improving the qualities of humanity through selective breeding. Henry Fairfield Osborn, a prominent eugenicist and president of the American Museum of Natural History from 1908 to 1933, noted that “to know the worst as well as the best in heredity; to preserve and to select the best—these are the most essential forces in the future evolution of human society.” (46) “The social application of eugenic theories,” one historian writes, “led to specific, detrimental effects on the lives of scores of immigrant families in the United States and to the genocide against Jews in Germany.” (47)
Immigration restrictions in the United States were buoyed by eugenicist sentiment. Harry Laughlin, the superintendent of the Eugenics Record Office at the Cold Spring Harbor Laboratory, appeared before Congress several times in the early 1920s promoting his belief that immigration was foremost a “biological problem.” The Cold Spring Harbor Laboratory, headed by Charles Davenport, was for all intents and purposes the headquarters of eugenics in the United States during first 40 years of the twentieth century. As Davenport’s number two at the laboratory, Laughlin fervently promoted eugenics, maintaining, for example, that recent immigrants from eastern and southern Europe were afflicted “by a high degree of insanity, mental deficiency, and criminality.” In his testimony before the House Committee on Immigration and Naturalization, Laughlin pleaded with Congress to restrict immigration so the United States would be allowed to “recruit and to develop our racial qualities.” (48)
Sterilization laws across the United States were also inspired by eugenic sentiment. In the twentieth century at least 60,000 so‐called “feeble‐minded” and genetically unfit Americans were sterilized “in the name of eugenics.” (49)
Criminals and those accused or convicted of sexual offenses were a primary concern of these eugenic laws. In 1907, the state of Indiana established the first sterilization law. By the early 1930s more than 29 other states had passed similar laws. (50) Advocates of criminal sterilization wrote that “criminals should be studied for evidence of dysgenic traits that are germinal in nature. Where found in serious degree parole should not be granted without sterilization.” (51) “Criminality,” “feeble‐mindedness,” and “idiocy” were all traits that eugenicists believed (mistakenly, of course) could be bred out of the species—traits eugenicists believed followed Mendelian patterns of inheritance and could therefore easily be excised. While California and North Carolina had the highest rates during the sterilization period, the last forced sterilization occurred in 1981 in Oregon. (52)
On matters of race, eugenicists were also quite vocal. This period “saw the dominance of the belief that human races differed hereditarily by important mental as well as physical traits, and that crosses between widely different races were biologically harmful.” (53) Well‐respected geneticists wrote openly that “miscegenation can only lead to unhappiness under present social conditions and must, we believe, under any social conditions be biologically wrong.” (54) In this same spirit eugenic racial science became a deviously powerful force in the Third Reich.
Eugenicists also supported racist thought in their claims about the genetic nature of black–white differences. Davenport’s work wasn’t simply a reflection of the racism of his times; his work provided scientific rationale and a language for that racism. For example, Charles Davenport offered his scientific expertise in the study of skin color difference, the application of eugenic doctrines to segregation and anti‐miscegenation laws, and ultimately to the definition of race itself. (55)
It is important to note that Nazi eugenics drew both scientific and ideological inspiration from its American counterpart. Madison Grant’s eugenic tract The Passing of the Great Race: The Racial Basis of European History, which preceded the rise of Nazism by more than a decade, nonetheless influenced German ideas about racial purity. The book, translated into German, explicitly stated, “The laws of nature require the obliteration of the unfit.” (56) American eugenicists themselves highlighted their ties to the Nazis, writing: “To one versed in the history of eugenic sterilization in America, the text of the German statute reads almost like the American model sterilization law.” (57) The ties went even deeper. Philanthropists, including the Rockefeller Foundation, gave grants to German eugenicists even after the rise of Hitler. (58) And even in the wake of mass sterilizations, concentration camps, and gas chambers the support of American eugenicists