The ability to detect dangerous animals rapidly in complex landscapes has been historically important during human evolution. Previous research has shown that snake images are more readily detected than images of benign animals. To provide a stringent test of superior snake detection in preschool children and adults, Experiment 1 consisted of two parts using a touch-screen visual search task. Reaction times to detect different target snakes embedded in matrices of lizards were compared with reaction times to detect target lizards embedded in matrices of snakes. Experiment 2 compared the visual salience of lions with that of similarly colored antelopes. This experiment tested the prediction that historically dangerous felid predators would also engender rapid detection. Results from the two experiments revealed that both preschool children and adults located snakes and lions more quickly than their nonthreatening counterparts. Experiment 3 examined the ability of children and adults to distinguish between similar appearing cows and horses. Preschool children and adult men exhibited no reliable differences in detecting the two animal types. Adult women located horses reliably faster than cows, suggesting that visual biases for some animals can be acquired after childhood. (Contains 6 figures.)