Genres evolve over time based on cultural and historical changes. In the 1940s-1950s, Western films featured solo heroes but then shifted to focus on groups in the 1960s-1970s to reflect workplace trends. Police/detective and spy genres replaced Westerns in the 1970s-1980s as urban crime and espionage grew in popularity. During the Great Depression, audiences sought escape from hardship through romantic comedies. Science fiction threats mirrored societal fears, like racial anxieties depicted in King Kong. By the 1990s, studios produced formulaic genre films and sequels to attract large audiences and ensure profitability given high production costs.