No single trait defines primates, or differentiates them from other mammalian orders (e. g, cf. Across primate species, there is a wide range of variation in: locomotor systems, manual dexterity, brain size relative to body size. Overall, however, primates as a group exhibit greater mobility of hands/feet/libs than species from other mammalian orders. Compared to other mammals of similar body sizes, primates tend to exhibit relatively larger brains (i. e. , large brains for their body sizes) An expanded neocortex in primates may be an evolutionary result of: The advantages gained through the use of tactical deception (i. e. , tom, or theory of mind, and the ability to gauge/understand the mental stat of others in your group and use that knowledge to your own advantage) so called. Enabling mutually beneficial cooperation, as well as success in foraging, and engaging in extractive foraging. A prolonged juvenile life history stage, which permits an extended period of socialization, would be key in all of the above.