Motivation is the catalyst that triggers human actions.
EVOLUTIONARY THEORIES OF EMOTION
Although numerous adaptive-evolutionary treatments of emotion have emerged over the years (e.g., Ekman & Davidson, 1994; Plutchik, 1994), an evolutionary-psychological approach distinguishes itself from other evolutionary approaches by adopting an explicitly adaptationist perspective (Barkow, Cosmides, & Tooby, 1992). An adaptationist perspective is guided by the simple assumption that the mind is comprised of many mental adaptations, each of which is the product of natural and sexual selection operating over many generations during the course of human evolution (Buss, Haselton, Shackelford, Bleske, & Wakefield, 1999).
