Recent work suggests physical activity can have important beneficial effects on the aging brain, however the underlying mechanisms remain poorly understood. An evolutionary-neuroscience approach may help us better understand these mechanisms and can provide a foundation for developing novel interventions to improve brain aging. Here, we suggest that, from an evolutionary perspective, physical activity mainly occurred during foraging, which combines aerobic activity with cognitively demanding tasks (e.g., spatial navigation and executive cognitive functions). Thus, mechanisms linked to neuroplasticity, including hippocampal neurogenesis, may be triggered by physical activity as a way to enhance cognitive needs during foraging tasks. If correct, simultaneous physical and cognitive challenges may lead to the strongest brain benefits. Using this evolutionary approach to brain health, we can form a foundation for novel interventions to improve brain aging today.