'You scratch my back and I scratch yours' versus 'love thy neighbour': two proximate mechanisms of reciprocal altruism

Evolutionary psychologists generally believe that reciprocal altruism, the mutual providing of benefits, is governed by a ‘You scratch my back and I scratch yours’, or scorekeeping mechanism. According to this view, individuals are primarily concerned with maintaining a balanced relationship; that is: in interactions with other individuals they avoid both to underbenefit and to overbenefit. In this way, they avoid to be exploited by individuals who reap the benefits of other people’s generosity without giving anything in return. However, there are several shortcomings to this view. First of all, it is doubtful whether a scorekeeping mechanism would have been beneficial under the conditions in which our ancestors evolved. Moreover, empirical support for a scorekeeping mechanism is weak: especially among friends the providing of mutual benefits seems explicitly not to be governed by a scorekeeping mechanism. The primary goal of this dissertation is to demonstrate that the scorekeeping mechanism is not so ubiquitous as is generally believed and to show that there is considerable evidence for the operation of a an alternative mechanism: a ‘Love thy neighbour’, or bonding mechanism. The bonding mechanism is primarily focused on helping one’s friends if they are in need. In addition, the question is addressed whether the bonding mechanism is more biologically prepared than the scorekeeping mechanism. A third goal is to examine the effect of emotions, which are considered to play an important role in the evolutionary psychological concept of proximate mechanisms, on typical bonding and scorekeeping behavior. The dissertation starts with an extensive introductory chapter discussing the evolutionary psychological perspective in general, as well as the issue of reciprocal altruism. It also elaborates on some well-known criticisms of evolutionary perspectives. The subsequent chapters examine data and findings from various sources for their support for the bonding and the scorekeeping mechanism. Chapter 2 consists of a review of the anthropological literature on food sharing in current hunter-gatherer societies. It provides no indisputable support for the scorekeeping mechanism. Sharing patterns either support the concept of a bonding mechanism or are empirically equivalent with both mechanisms. Chapter 3 presents simulation data about the relative success of a scorekeeping strategy and a bonding strategy. The results show that actors using a bonding strategy are equally successful in maintaining their numbers when confronted with non-cooperative actors, as compared to actors using a scorekeeping strategy. Moreover, when conditions are harsh, bonding actors are more successful in invading a population of non-cooperative actors. Chapters 4 and 5 describe the results of scenario-experiments, in which subjects were confronted with scenarios posing a dilemma between bonding behavior (helping someone in need) and scorekeeping behavior (refusing to help someone who is in one’s debt, and repaying a creditor). Subjects were more likely to perform bonding behavior if the object of help was assistance in the case of illness than they were if it concerned the lending of money. In addition, friends induced more bonding behavior than acquaintances. There was no support that one of either mechanisms was biologically more prepared. Emotions were shown to play an important role. Helping a person in need appeared to be correlated with emotions of warmth and commitment. Refusing to help a person who is in one’s debt was correlated with retaliatory emotions, like irritation, indignation, and anger. In contrast to expectations, the decision to repay a creditor rather than help a needy person was not correlated with emotions like gratitude, guilt and fear of retaliation.