AI quiz split_23-27.pdf

ChALLENGES OF PARENTiNG AND KiNShiP 240 resources. Among certain bird species, siblings jostle and jockey for the best position to gain food from the parents returning to the nest. Siblings amplify their levels of begging in attempts to secure more than their fair share. Occasionally, a bird will...

ChALLENGES OF PARENTiNG AND KiNShiP 240 resources. Among certain bird species, siblings jostle and jockey for the best position to gain food from the parents returning to the nest. Siblings amplify their levels of begging in attempts to secure more than their fair share. Occasionally, a bird will commit “siblicide” by pushing a sibling out of the nest. A review of a book on the natural history of families provides an apt summary: [I]n spite of occasional outbreaks of harmony, families are shaped by confict. In birds, parents deliberately generate much confict within families. They screen their offspring for quality by stage-managing conficts among them, compensate for the uncertainty of future food supplies by optimistically producing more young than they expect to rear, and generate insurance against reproductive failure by producing surplus offspring. As a result of these parental decisions, family life is flled with frequently gory and often fatal struggles between offspring. (Buckley, 2005, p. 295). Among mammalian species, siblings sometimes compete by increasing their level of suckling, draining the maternal teats to the detriment of their littermates. These are all forms of “scramble competition,” and there is every reason to assume that similar phenomena occur in human families. Accounts of sibling confict go far back in human recorded history, as exemplifed by this quote from Genesis in the King James Bible: “Israel loved Joseph more than all his children, because he was the son of his old age: and he made him a coat of many colours. And when his brethren saw that their father loved him more than his brethren, they hated him, and they could not speak peaceably unto him.” The biblical account of the brothers Cain and Abel is also revealing, because the killing was caused, in some accounts, by confict over a woman. Extreme forms of sibling confict such as siblicide are rare in humans, but they do occur, and the circumstances in which they occur are revealing. Brothers, far more than sisters, sometimes become sexual competitors. Statistically, most murders of siblings are indeed brothers killing brothers. The causes are almost invariably conficts over women or conficts over resources that are needed to attract women (Buss, 2005). Human siblings also compete with each other over grandparental resources (Fawcett, van den Berg, Weissing, Park, & Buunk, 2010, p. 23). They use subtle tactics such as maintaining regular contact with grandparents and more overt tactics such as direct requests for money. And cases of siblings suing each other over inheritances when a parent or grandparent dies are so common that they only make headlines when vast sums of money are involved. There is also evidence that resource competition among siblings, such as confict over limited land in farming communities, causes some siblings to migrate out of their natal area in order to secure resources elsewhere (Beise & Voland, 2008). The second form of confict is parent–ofspring confict, explored in Chapter 7. The optimal allocation of resources from the parent’s perspective, for example, might be to give equal shares of resources to each ofspring, although other factors such as need and ability to utilize resources obviously cause deviations from equal allocation. From the child’s perspective, however, the optimal resource allocation usually involves taking more for the self at some expense to a sibling and parent. There is an old joke that illustrates this confict. A son goes of to college and, after 3 months, writes a letter home pleading for more money: “Dear Dad: No mon, no fun, your son.” In response, the father writes back: “Dear Son: Too bad, so sad, your Dad.” Selection favors adaptations in children to manipulate parents to secure a larger share of resources and counter-adaptations in parents not to bend solely to one child’s desires. The third fundamental type of family confict involves conficts between the mother and father over resource allocation, or parental confict. Confict between mothers and fathers centers on 8 PRObLEMS OF KiNShiP how much parental investment each will give to the ofspring within the family. It is sometimes benefcial, for example, for one parent to withhold his or her own resources for other avenues of reproduction. Either parent might divert resources to his or her own kin and will proft if the other parent provides more resources directly to their ofspring. Furthermore, either parent might use resources to obtain matings and consequently produce children who are genetically unrelated to the other parent, resulting in confict between the parents. It would be surprising if humans had not evolved adaptations designed to deal with these forms of confict, such as sensitivity to the other parent’s diversion of resources or psychological manipulation such as guilt induction designed to extract additional resources from the other parent. We often grow up believing that families should be harmonious sanctuaries within which mutual sharing yields the maximum beneft for everyone. As a consequence, when we experience turmoil, disagreement, and clashes with our parents, siblings, or children, we feel that something has gone badly awry. Entire professions, such as certain forms of family counseling, are designed to deal with the psychological turmoil that results from family confict. An evolutionary perspective suggests that three fundamental sources of conficts—between siblings, between parents and ofspring, and between mothers and fathers—are likely to be pervasive. This might not help the daughter who is battling her mother, the parents who are at odds over resource allocation, or siblings who cannot stand each other. Understanding the evolutionary logic of family confict, however, might help people to gain some perspective from the realization that they are not alone in these experiences. Summary We started this chapter by delving deeper into Hamilton’s (1964) theory of inclusive ftness, formalized by Hamilton’s rule c < rb. For altruism to evolve, the cost to the actor must be less than the benefts provided, multiplied by the genetic relatedness between the actor and the recipient. In one bold stroke, this theory ofered one answer to the question of how altruism could evolve. It simultaneously extended Darwin’s defnition of classical ftness (personal reproductive success) to inclusive ftness (personal reproductive success plus the efects of one’s actions on the ftness of genetic relatives, weighted by the degree of genetic relatedness). Next we drew out the profound theoretical implications of inclusive ftness theory for humans. For example, (1) there will be a special evolved psychology of kinship involving psychological mechanisms dedicated to solving the difering adaptive problems when dealing with siblings, half siblings, grandparents, grandchildren, aunts, and uncles; (2) sex and generation will be critical categories diferentiating kin because these dimensions defne important properties on one’s ftness vehicles; (3) kin relationships will be arrayed on a dimension from close to distant, the primary predictor of closeness being genetic relatedness; (4) cooperation and kin solidarity will be a function of genetic relatedness among kin; (5) older kin members will encourage younger kin members to be more altruistic toward genetic relatives such as siblings than younger kin members will naturally be inclined to be; (6) one’s position within a family will be central to one’s identity; and (7) people will exploit kin terms to infuence and manipulate others in non-kin contexts (e.g., “Brother, can you spare some cash?”). Empirical studies confrm the importance of kinship as a predictor of helping behavior. One study documented that alarm calling among ground squirrels, a potentially costly endeavor to the caller because it draws the attention of predators, occurs when close kin are likely to be nearby. Helping kin frst requires the ability to recognize kin. Humans have at least four kin recognition mechanisms: (1) association; (2) odor; (3) kin classifcation systems based on a “universal grammar” that includes genealogical distance, social rank, and group membership resemblance; and (4) resemblance, facial or behavioral. A study of 300 Los Angeles 241 CHAPTER 9 Cooperative Alliances Learning Objectives Afer studying this chapter, the reader will be able to: ■ explain the problem of altruism. ■ summarize the theory of reciprocal altruism. ■ Analyze why “tit for tat” is such a successful strategy. ■ Provide two examples of reciprocal altruism in non-human animal species. ■ Describe why humans must have cheater-detection adaptations in order for reciprocal altruism to evolve. ■ Compare and contrast the costs and benefts of friendship. ■ list and describe the two key problems that must be solved when establishing coalitions. If thou wouldst get a friend, prove him frst, and be not hasty to credit him. For some man is a friend for his own occasion, and will not abide in the day of thy trouble. . . . Again, some friend is a companion at the table, and will not continue in the day of afiction. . . . If thou be brought low, he will be against thee, and will hide from thy face. . . . A faithful friend is a strong defense: and he that hath found such a one hath found himself a treasure. Nothing doth countervail a faithful friend. —Sirach 6:7–15 A story is told of two friends, one of whom was accused of a robbery he had not committed. Although he was innocent, he was sentenced to 4 years in jail. His friend, greatly distressed by the conviction, slept on the foor each night that his friend was in jail. He did not want to enjoy the comfort of a soft bed knowing that his friend was sleeping on a musty mattress in a jail cell. Eventually, the imprisoned friend was released, and the two remained friends for life. How can we explain such puzzling behavior? Why do people form friendships and long-term cooperative alliances? The Evolution of Cooperation People commonly make personal sacrifces for their close friends. Every day, people help their friends in many ways large and small, from giving advice and sacrifcing time to rushing to a friend’s aid in a time of crisis. Acts of friendship of this sort pose a profound puzzle. Natural selection is intrinsically competitive, a feedback process in which one organism’s design features out-reproduce those of others in an existing population. Sacrifces are costly to those who make them, yet they beneft the people for whom the sacrifces are made. How could such patterns of friendship and altruism evolve? PROBLEMS OF GROUP LIVING 248 The Problem of Altruism In Chapter 8, we saw how one form of such altruism can evolve when the recipients of the aid are genetic relatives. This sort of altruism is predicted by inclusive ftness theory. Your friends, however, are not usually your genetic relatives. So any cost you incur for a friend results in a loss to you and a gain to the friend. The great puzzle is: How could altruism among nonrelatives possibly evolve, given the competitive adaptations that tend to be produced by natural selection? This is the problem of altruism. An “altruistic” design feature aids the reproduction of other individuals, even though it causes the altruist who has this feature to sufer a ftness cost. The puzzle is complicated further by the fndings that altruism is neither new nor unusual. First, there is evidence that social exchange—a form of cooperation—occurs across human cultures and is found frequently in hunter-gatherer cultures that are presumed to roughly resemble the ancestral conditions under which humans evolved (Allen-Arave, Gurven, & Hill, 2008; Cashdan, 1989; Lee & DeVore, 1968; Weissner, 1982). Second, other species that are far removed from humans, such as vampire bats, also engage in forms of social exchange (Wilkinson, 1984). Third, other primates besides humans, such as chimpanzees, baboons, and macaques, also engage in reciprocal helping (de Waal, 1982). Taken together, this evidence suggests a long evolutionary history of altruism. A Theory of Reciprocal Altruism One solution to the problem of altruism has been developed, in increasingly elaborate and sophisticated ways, by the theory of reciprocal altruism (Axelrod, 1984; Axelrod & Hamilton, 1981; Cosmides & Tooby, 1992; Trivers, 1971; Williams, 1966). This theory states that adaptations for providing benefts to nonrelatives can evolve as long as the delivery of benefts is returned or reciprocated at some point in the future. The beauty of reciprocal altruism is that both parties beneft—a win-win situation. Consider an example: Two hunters are friends. Their success at hunting, however, is erratic. During the course of a week, perhaps only one of the hunters will be successful. The following week, however, the other hunter might be successful. If the frst hunter shares his meat with his friend, he incurs a cost of lost meat. This cost, however, might be relatively small because he may have more meat than he or his immediate family can consume before it spoils. The gain to his friend, however, might be large if he has nothing else to eat that week. The following week, the situation is reversed. Thus, each of the two hunters pays a small cost in lost meat that provides a larger beneft to his friend. Both friends beneft by the reciprocal altruism more than they would if each one selfshly kept all the meat from his kill for himself. Economists call these net win-win benefts gains in trade—each party receives more in return than it costs to deliver the beneft. In evolutionary terms, these gains in trade set the stage for the evolution of reciprocal altruism. Those who engage in reciprocal altruism will tend to out-reproduce those who act selfshly, causing psychological mechanisms for reciprocal altruism to spread in succeeding generations. One of the most important adaptive problems for the reciprocal altruist is ensuring that the benefts it bestows will be returned in the future. Someone could pretend to be a reciprocal altruist, for example, but then take benefts without responding in kind later. This is called the problem of cheating. Later in this chapter, we will examine empirical evidence that suggests that humans have evolved specifc psychological adaptations designed to solve the problem of cheating. First, however, we look into a computer simulation that demonstrates that reciprocal altruism can evolve, and we examine a few non-human species to provide concrete examples of the evolution of cooperation. 9 COOPERATIVE ALLIANCES 249 Tit for Tat The problem of reciprocal altruism is similar to a game known as the “prisoner’s dilemma.” The prisoner’s dilemma is a hypothetical situation in which two people have been thrown in prison for a crime they are accused of committing together and of which they are indeed guilty. The prisoners are held in separate cells so that they can’t talk to each other. Police interrogate both of the prisoners, trying to get each to rat on the other. If neither one implicates the other, the police will be forced to set them both free for lack of evidence. This is the cooperative strategy from the prisoners’ perspective; it is the strategy that would be best for both of them. In an attempt to get each prisoner to rat on (or defect from) the other, however, the police tell each that if he confesses and implicates his partner, he will be set free and given a small reward. If both prisoners confess, however, they will both be sentenced to jail. If one confesses and the other does not, then the implicated partner will receive a stifer sentence than he would have received if both confessed. The prisoner’s dilemma is illustrated in Figure 9.1. In this scheme, R is the reward for mutual cooperation, where neither prisoner tells on the other. P is the punishment each prisoner receives if both confess. T is the temptation to defect— the large reward given in exchange for implicating the other. S is the “sucker’s payof,” the penalty one incurs if his partner defects and he does not. This is called the prisoner’s dilemma because the rational course of action for both prisoners is to confess, but that would have a worse outcome for both than if they decided to trust each other (hence the dilemma). Consider the problem of Player A. If his partner does not confess, A will beneft by defecting—he will be set free and will receive a small reward for implicating his partner. On the other hand, if his partner defects, Player A would be better of defecting as well; otherwise, he risks receiving the stifest penalty possible. In sum, the logical course of action, no matter what one’s partner does, is to defect, even though cooperation would result in the best outcome for both. This hypothetical dilemma resembles the problem of reciprocal altruism. Each person can gain from cooperating (R), but each is tempted to gain the beneft of a partner’s altruism without reciprocating (T). The worst scenario for each individual is to cooperate and have a partner who defects (S). If the game is played only once, then the only sensible solution is to defect. Robert Axelrod and W. D. Hamilton (1981) showed that the key to cooperation occurs when the game is repeated a number of times but each player does not know when the game will end, as often happens in real life. This is the payof matrix used in the tournament run by Robert Axelrod. A game consisted of 200 match-ups between two strategies. The game is defned by T > R > P > S and R > (S + T)/2. Figure 9.1 The Game of Prisoner’s Dilemma Source: Axelrod, R., & Hamilton, W. D. (1981). The evolution of cooperation. Science, 211, 1390–1396. Copyright © 1981 American Association for the Advancement of Science. Reprinted with permission.