One of the many mysteries of human evolution is why humans display a strong tendency towards right handedness. Over 90% of humans are right handed, but no other mammal species shows this strong of a lateral dominance. Hand preference is a manifestation of laterality, meaning there is a behaviorally dominant side or limb preference, and may be related to hemispheric dominance in the brain. In many primate species left handed individuals are less likely than right handed individuals to explore new objects and situations, which suggests a relationship between hemispheric specialization of emotional states and motor function. From basic preferences in hand use, eye use, and head turning most mammals express preferences and some of these preferences change based on emotional state.