The authors investigated the idea that memory systems might have evolved to help us remember fitness-relevant information--specifically, information relevant to survival. In 4 incidental learning experiments, people were asked to rate common nouns for their survival relevance (e.g., in securing food, water, or protection from predators); in control conditions, the same words were rated for pleasantness, relevance to moving to a foreign land, or personal relevance. In surprise retention tests, participants consistently showed the best memory when words were rated for survival; the survival advantage held across recall, recognition, and for both within-subject and between-subjects designs. These findings suggest that memory systems are "tuned" to remember information that is processed for fitness, perhaps as a result of survival advantages accrued in the past.