Throughout history, genetics have often been at the center of controversy. The desire to improve humankind has been present in many societies and different times. Sir Francis Galton coined the term eugenics in 1883: a formalized field of study aiming to improve hereditary traits in humans. He based this theory on extrapolations from some of the publications of his relative, Charles Darwin. Darwin wrote about how species evolve through the process of natural selection: as resources are limited and some individuals do better than others, those better suited to a particular environment tend to produce more offspring, and thus their genetically determined traits tend to become more prominent in the next generation. Darwin also showed how this process is similar to the artificial selection humans have used to generate varieties of domestic animals; he made a great study of the various fancy pigeon breeds, looking at how breeders picked particular wild rock pigeon individuals bearing unusual traits (such as ruffled necks and particular color patterns) to breed from and develop new varieties. Galton believed similar processes could enhance desirable traits, such as higher intelligence, in humans.
Eugenics inspired many social and political movements around the world during the 19th and 20th century. After the Second World War however, eugenics started loosing momentum and in modern times the term has a negative connotation.
Probably one of the most prominent and deadly adoptions of eugenic principles occurred in Europe during the Nazi era. In the Nazi ideology, the advent of medical care and modern comfort had eliminated the natural processes keeping the human species fit. They believed that "defective" individuals would have not survived under normal conditions and had become an expensive and unnecessary drain on society. This misinterpretation of Darwin's "survival of the fittest" is at the core of one of darkest episodes of modern history.
Both positive and negative eugenic policies were adopted in Germany and the countries they invaded. "Positive" practices aimed at favoring reproduction of individuals bearing desirable traits, whilst "negative" practices sought to limit the reproduction of, or simply to eliminate altogether, individuals bearing "undesirable" traits. People judged as superior representatives of the master race, the Aryans, were encouraged to reproduce more, while people seen as inferior were sterilized and euthanized by the hundreds of thousands.
In the United States, eugenics were adopted after the Civil War (Allen, et al., 2010). Economic and social instability, coupled with the new challenges of industrialization, brought forth progressivism. With this new general atmosphere of reform and trust in science came the idea of "social engineering" to manage and shape a better society. At the time, eugenicists believed that many of the social issues such as criminality, alcoholism and pauperism could be explained by the inheritance of defective genetic material or "germ plasm." As these "affected" individuals were often supported through public welfare and the state, the reproduction of such individuals brought a large cost to society that could be avoided by mandatory sterilization. The views of eugenics in the US also lined up with the interests of those alarmed by the rise of the socialist party and the strengthening of labor unions. The blame in this case was placed on immigrants from southern Europe who were believed to carry defective germ plasm and associated characteristics that should not be allowed to enter the American genetic pool.
Unfortunately, eugenic ideology tainted policies as well as American popular culture throughout a large part of the 20th century. Immigration restrictions were adopted to keep out immigrants whose genetics were judged inferior. More than 60,000 Americans were sterilized involuntarily. In fact, sterilization in institutions housing patients with mental problems was not banned in some states until the 1970s. Eugenics also provided new, supposedly "scientific" arguments in favor of racial segregation. People were also influenced by eugenics in their daily lives. At a state fair, you could sign up for "Fitter Families Contests" where you and your family members could be examined and rewarded for "superior" genetic heritage. You could read the latest on eugenics in the Eugenical News published by the Galton Society.
Much of the science conducted by eugenicists was inherently flawed. The central goal of eugenics is an attempt to apply Mendelian laws to human characteristics. To do so, researchers attempted to trace the inheritance of a trait through pedigrees or family trees. The studied traits were expected to fit the simple Mendelian scenario of one locus, two alleles, autosomal or sex-linked, with simple dominant and recessive relationships. But most of the traits eugenicists were interested in were complex in nature, often difficult to quantify (for example, sense of humor and self respect), and in some cases probably did not have much of a genetic basis (pauperism). Thus, their observations and conclusions were often misleading.
Despite the rejection of eugenic science, some of its ideas remain in the public mind, even today. We often hear how something making a particular group of people "inferior" or "superior" has a solely genetic basis. Shows about crime and its prosecution sometimes have episodes where criminality can allegedly be explained by a single gene. Studies looking at IQ have estimated its heritability could be as low as 40%. In this case, someone's IQ is mostly determined by the environment they grow up in. Thus education, early stimulation, diet or the myriad factors that have been implied in IQ development, could make a large difference. Other studies estimate IQ heritability to be as high as 80%. In this case, genetic factors greatly influence any variation in IQ, while the environment plays only a small role. These contrasting findings have led to various interpretations of variation in IQ across different races that have fueled racial debates. However, most scientists agree that there are no significant genetic differences in human intelligence at the race level; science provides absolutely NO justification for discrimination. Extrapolations of scientific findings should be interpreted with care to avoid falling into the same patterns that have proved so detrimental in the past.