1. The theory or belief that all or most traits of organisms have evolved because they are adaptive and provide a survival or reproductive advantage.
Usage: biology; evolutionary theory
2. The methodological approach in evolutionary biology that explains biological features primarily through natural selection and adaptation rather than other mechanisms.
Usage: biology; scientific methodology

Examples

• Adaptationism assumes that the peacock's elaborate tail evolved because it attracts mates.
• Critics of strict adaptationism argue that some traits arise through genetic drift rather than selection.
• The debate between adaptationism and neutralism has shaped modern evolutionary biology.
• Adaptationism provides a powerful framework for understanding why animals have specific behaviors.
• Some biologists reject adaptationism as too simplistic for explaining complex evolutionary patterns.
• Gould and Lewontin challenged adaptationism by highlighting the role of non-adaptive traits.