Why did eugenicists compare human reproduction with the breeding of crops and livestock?

Eugenicists compared human reproduction to the breeding of crops and livestock because they viewed human traits as heritable characteristics that could be controlled through selective breeding. By applying agricultural practices to human populations, they sought to perpetuate "favourable traits" and eliminate what they termed "defective stock".312

This comparison was rooted in the belief that nature was far more influential than nurture in shaping humanity. Influenced by Charles Darwin’s theory of natural selection and the rediscovery of Gregor Mendel’s laws of heredity, eugenicists argued that humans could—and should—take control of their own evolution.13

It is essential to recognize that this dehumanizing framework was fundamentally flawed and ethically bankrupt. By treating human beings as livestock, eugenicists promoted discriminatory ideologies that were later used to justify horrific human rights abuses, including the state-sponsored extermination of entire groups of people. The reduction of human life to biological "stock" is a profound violation of the inherent dignity and equality of every individual.3