In Lewin’s equation, person refers to the characteristics of the individual human being. People are born with skills that allow them to successfully interact with others in their social world. Newborns are able to recognize faces and to respond to human voices, young children learn language and develop friendships with other children, adolescents become interested in sex and are destined to fall in love, most adults marry and have children, and most people usually get along with others.
People have these particular characteristics because we have all been similarly shaped through human evolution. The genetic code that defines human beings has provided us with specialized social skills that are important to survival. Just as keen eyesight, physical strength, and resistance to disease helped our ancestors survive, so too did the tendency to engage in social behaviors. We quickly make judgments about other people, help other people who are in need, and enjoy working together in social groups because these behaviors helped our ancestors to adapt and were passed along on their genes to the next generation (Ackerman & Kenrick, 2008; Barrett & Kurzban, 2006; Pinker, 2002). Our extraordinary social skills are primarily due to our large brains and the social intelligence that they provide us with (Herrmann, Call, Hernández-Lloreda, Hare, & Tomasello, 2007).
The assumption that human nature, including much of our social behavior, is determined largely by our evolutionary past is known as evolutionary adaptation (Buss & Kenrick, 1998; Workman & Reader, 2008). In evolutionary theory, fitness refers to the extent to which having a given characteristic helps the individual organism to survive and to reproduce at a higher rate than do other members of the species who do not have the characteristic. Fitter organisms pass on their genes more successfully to later generations, making the characteristics that produce fitness more likely to become part of the organisms’ nature than are characteristics that do not produce fitness. For example, it has been argued that the emotion of jealousy has survived over time in men because men who experience jealousy are more fit than men who do not. According to this idea, the experience of jealousy leads men to protect their mates and guard against rivals, which increases their reproductive success (Buss, 2000).
Although our biological makeup prepares us to be human beings, it is important to remember that our genes do not really determine who we are. Rather, genes provide us with our human characteristics, and these characteristics give us the tendency to behave in a “human” way. And yet each human being is different from every other human being.
Evolutionary adaption has provided us with two fundamental motivations that guide us and help us lead productive and effective lives. One of these motivations relates to the self—the motivation to protect and enhance the self and the people who are psychologically close to us; the other relates to the social situation—the motivation to affiliate with, accept, and be accepted by others. We will refer to these two motivations as self-concern and other-concern, respectively.