The ultimate level of causation refers to the behavior's evolutionary significance; how the behavior enhances reproductive fitness. The proximate cause refers to the immediate cause of a behavior, whether that be hormonal, neurological, cognitive, interpersonal, or cultural.

What is the difference between ultimate and proximate causation biology?

Ultimate explanations are concerned with the fitness consequences of a trait or behavior and whether it is (or is not) selected. In contrast, proximate explanations are concerned with the mechanisms that underpin the trait or behavior—that is, how it works.

What is the difference between proximate and ultimate reasoning?

Proximate explanations focus on things that occur during the life of an individual. Ultimate explanations focus on things that occur in populations over many generations.