Eugenics was the belief that society could be improved by controlling human reproduction in order to increase traits deemed desirable, while reducing those there were undesirable. Francis Galton, cousin of Charles Darwin, was heavily influenced by Origin of the Species, taking Darwin’s biological idea and thought to apply it to society, believing characteristics such as intelligence, poverty, and morality were passed down through familial generations, and could therefore be bred, much as farmers breed plants and animals. Galton a many of many interests, used statistics to analyze trends of certain traits such as eminence while studying the histories of wealthy or prominent families.
Eugenicists believed society at large could be improved through selective reproduction. Galton promoted positive eugenics, whereby people showing a high degree of desirable traits would be incentivized to have more children together. The reverse of this was negative eugenics, a conception where people labeled as unfit were discouraged, or sometimes even prohibited, from reproducing. This idea gave rise to forced sterilization laws in some countries during the early 20th Century.
Peas and fruit flies were important as they were used to help scientists study and understand how heredity and genetics functioned, as they reproduce very quickly, allowing us to see generational changes in a short amount of time. The work of Gregor Mendel, while initially ignored by the scientific community, would a few decades later inspire several others, De Vries, Spillman, and Correns to reinvigorate the study. Fast forward another decade and a group of scientists under Thomas Hunt conducted a series of genetic experiments using fruit flies, and pioneered the usage of linkage maps to find chromosomal orders. While genetics would go on to become a legitimate field of study, eugenics became widely discredited due to oversimplifying hereditary assumptions, its ignorance of social factors, and its justification of discriminatory policies.