Although most will be at least somewhat familiar with the biological role hormones play during puberty and pregnancy, many are likely unaware that hormones - chemical messengers that are secreted by cells and that travel through the body to reach specialized receptors - impact multiple aspects of our lives from conception onward. Behavioral endocrinology and evolutionary psychology are complementary disciplines wherein scholars seek to understand human behavior. Evolutionary psychologists contend that human psychology and behavior are functional outcomes of natural and sexual selection pressures encountered in the ancestral environment. In this view, selection pressures designed adaptations of the mind and body, which produce behavior through a variety of psychological, neurological, and physiological mechanisms.