John B. Calhoun

John B. Calhoun was an American ethologist and psychologist known for his studies on population density and behavior. In the 1960s, he conducted experiments with rats in controlled environments, observing how overcrowding affected their social behavior, leading to stress, aggression, and even social breakdown. His most famous experiment, "Universe 25," illustrated the consequences of overpopulation on social structures and mental health. Calhoun's work has been influential in discussions about the implications of urbanization, environmental sustainability, and human society, reflecting how living conditions can dramatically impact behavior and societal functioning.