The study of human nature is a legitimate scientific enterprise.
Human beings are social animals, and the tenor of our social life is one of the most important influences on our mental health. Without positive, durable relationships, both our minds and our bodies fall apart.
Quite simply, cognition refers to thinking. There are the obvious applications of conscious reasoning—doing taxes, playing chess, deconstructing Macbeth—but thought takes many subtler forms, such as interpreting sensory input, guiding physical actions, and empathizing with others.
Our bodies evolved over eons, slowly calibrating to the African savanna on which 98 percent of our ancestors lived and died. So, too, did our brains. Evolutionary psychology postulates that the mind is shaped by pressure to survive and reproduce.