Which statement describes proximate causes in behavioral biology?

• A. They describe immediate triggers of behavior such as hormones and development
• B. They describe long-term evolutionary reasons
• C. They describe population-level trends
• D. They describe random mutations

Answer: (A)

Proximate causes explain how a behavior happens, focusing on immediate mechanisms that trigger it. This includes hormones, neural circuits, sensory cues, and developmental processes that bring the behavior into action. The best statement captures this idea by pointing to immediate triggers like hormones and development, which show the step-by-step, mechanical side of why a behavior occurs. In contrast, ultimate causes address why the behavior evolved in the first place—its adaptive value and evolutionary history. The other options describe longer-term or indirect factors (such as population trends or random mutations) that shape evolution rather than the quick, present-mactors of the behavior itself. For example, a rise in testosterone can proximate-trigger mating behaviors, whereas the evolutionary reason those behaviors persist is an ultimate question about fitness.