Human nature and personality variation: Reconnecting evolutionary psychology with the science of individual differences

The scientific study of human behavior from a modern evolutionary perspective began in the 20th century with disciplines such as human ethology and behavioral ecology as well as sociobiology. This early work focused on the characterization of a universal human nature that could be observed across all societies and cultures, one believed to have emerged in part from evolutionary processes. With the passage of time a newer evolutionary discipline, evolutionary psychology, emerged in the early 1990 s and quickly flourished. The focus on human nature was retained from its forerunners, but the primary focus of the field underwent a decided shift. Gone was the emphasis on observable behaviors and in its place moved psychological and cognitive functioning. At the same time, the new field took an interesting departure from other branches of psychology by largely relegating the significance of individual differences across cognitive and personality styles (whether heritable or environ-mental in origin) to a minor role. In this paper, we review the primary original arguments for minimizing or ignoring the importance of individual differences in personality and cognition, all in the service of making the case that the study of human nature, and evolutionary psychology more generally, is not at odds with individual differences research. The two fields have always been complementary, with one serving as a frequent source of insight for the other.