Seventeen

WHAT DO WE KNOW OF THE SOCIAL BRAIN?

Camilo José Cela Conde, Miguel Ángel Capó, Marcos Nadal and Carlos Ramos

The objective of this study is to analyze scientific findings capable of describ- ing the mechanisms underlying the human behaviors of cooperation and con- flict on a biological and cognitive level. The underlying question we aim to answer is whether we can understand these behaviors in a more profound way than through mere folk psychology models. Such an understanding, based on the certainty that conflict and cooperation involve mechanisms fixed by natu- ral selection, would necessitate explanation of the appearance of cognitive processes related to these behaviors and identifying the causal biological mechanisms. To do so we review three types of approach to this question: the sociobiological, neurobiological, and genetic approaches.

1. The Sociobiological Approach to Social Behavior

Modern study of the biological roots of social behavior goes back to the flour- ishing of a new approach toward animal behavior constructed from ethology in the sixties and consolidated in the mid-seventies of last century as a field called sociobiology. Edward O. Wilson described sociobiology as the system- atic study of the social bases of any social, animal, or human behavior.1 The factors differentiating sociobiology from ethology is the adoption of the so- called gene’s point of view, and development of a conceptual apparatus based on that perspective. Before the consolidation of sociobiology, many etholo- gists assumed that natural selection would have favored the appearance of behavior that was costly for the individual yet favorable toward the group. Accordingly, we could explain many aspects of animal social behavior as a sacrifice by the individual for the collective good. Vero Copner Wynne- Edwards was one of the researchers who contributed most in this field.2 He argued that groups of individuals or species that limited their growth accord- ing to their environmental resources had greater survival rates than those that overexploited their habitats because the behavior of some individuals altruisti- cally foregoing reproduction. George C. Williams’ criticism of group selection models, and his con- vincing arguments in favor of more parsimonious explanations, prepared the way for the work of Edward Wilson and Richard Dawkins, who popularized adoption of the genetic perspective to adequately understand social behavior.3 202 CAMILO JOSÉ CELA CONDE, ET AL.

From that perspective, they considered animal behavior, including social be- havior, as a medium developed by the genes to ensure their transmission to descendents. As Kevin N. Laland and Gillian R. Brown stated, scientists came to think of the body and its functions as mere vehicles to transport and trans- mit genes.4 But this stance interferes with explanation of altruist behavior. If the objective of genes, and the social behavior related to them, is to maximize their chance of being transmitted to future generations, how can we explain the behavior of an individual who reduces their chances of survival and repro- duction to increase those of another individual? William Donald Hamilton based his answer, known as kin selection, on our knowledge that closely related individuals share copies of many genes.5 Accordingly, animals can increase the presence of those common genes in the next generation by favoring reproduction in close relatives. Although the al- truist act of sacrificing yourself to help someone else might reduce your chance to transmit your genes, the probability of transmitting other copies of your genes increases whenever the beneficiary is a close relative. Hamilton predicted that this behavior would be selected whenever the cost to the altruist individual was less than the benefit for the receiver or receivers, multiplied by the probability that the relative possessed an identical gene. The closer our kin, the greater the sacrifice we are prepared to make through an altruist act. After reviewing Hamilton’s work, Robert Trivers introduced the idea of reciprocal altruism to answer the question of altruistic behavior between unre- lated organisms.6 He suggested that altruist behavior, which was initially costly for the agent yet beneficial for the recipient, could appear among unre- lated individuals who interacted during a long period, whenever there was a high probability that the other individual would reciprocate the altruist act in the future. Under these conditions, over time, both individuals would have gained more through their altruistic interaction than if they had not cooper- ated. In cases such as these, reciprocal altruism runs against certain individu- als’ tendency not to reciprocate—or to deceive. To avoid deceivers appearing or those deceivers re-offending, human beings have developed procedures such as altruistic punishment.7 Currently, we approach the biological bases for social behavior from perspectives inherited from sociobiology, such as evolutionary psychology, human behavioral ecology, the theory of dual inheritance or memetics. Al- though these perspectives differ in their objectives, methods and spheres of application, they all assume that a special characteristic of the human brain enables human social behavior, tied to cooperation or conflict. Even though no wide consensus exists regarding the human brain’s special characteristics, which allow our cognitive and behavioral sophistication in the sphere of social relationships, a good chance exists that we need to review them. In the next section, we do this from an evolutionist approach.