Social Behavior

Chapter on Social Behavior from Psychology: An Evolutionary Approach  by J.C. Steven Gaulin, Donald McBurney. 

Summary by  Sharen Finkelstein, Amanda Smolich, Gloria Gonzalez, and Nicole Cipoletti 


What is socialization? This term means that any member of any species will interact and associate with other members of its same species. The association may produce benefits and costs to both the group and the individual. Animals are social when "being social" represents a benefit. In contrast, if the social behavior represents more costs than benefits, they will develop solitary habits. Techniques that help to avoid predators and food acquisition are examples of the benefits that result from socialization. A group of monkeys or apes is more efficient in finding resources, and less vulnerable to predators. Therefore socialization in this case benefits the survival and reproduction of the species. In other cases, like the orangutan (pongo pygmaeus), being social is not as beneficial. Orangs are found in large rain forest trees. This characteristic makes them invulnerable to predators; they do not need from a group in order to protect themselves.

There are other facts that interfere in the socialization phenomenon among species. Food acquisition, for example, depends on how the food of a particular species is distributed in terms of size of the area, and variety of resources. Apes and monkeys, for example, live around tropical forests; they have less competition in finding resources. They live in areas where the variety of resources is large; there are different species of trees with different fruit cycles. This type of resource distribution favors social habits. On the other hand, in areas of temperate forest the variety of trees is very limited and the fruits have a standard growth according to specific seasonal patterns. Thus the species that live in these areas are few and not social. The competition among them is bigger. If the food area is relatively small for a particular species, the socialization habits will not benefit that species.

Socialization in many species is a key factor for adaptation and therefore the survival of the species. In terms of food acquisition social tendencies may favor the survival of the species. There are some species like lions, hyenas, and wolves that hunt together, so they can capture more or larger prey. In other cases some animals associate with each other in order to cope with different environmental risks. Birds, for example, reduce aerodynamic drag by flying in formation.

Selection pressures favoring Human Sociality


The evolution of sociality in humans has been debated by different anthropologists. Some say that our ancestors inhabited more open and less forested areas. This idea correlates with the fact that open habitats contain herds of grazing animals, which represent a potential food resource. Thus humans consolidated for hunting purposes resulting in more success than solitary humans. Even though the food acquisition problem was resolved, in these open areas they were also exposed to a high risk of being killed by other species.

The evolution of social behavior has been studied from other points of view. One of them is related to the human physiological similarities with other primate species. The African great ape (closest living relative to the human), which has social tendencies, is one type of evidence that proves the evolution of social behavior. However, it is contradictory with the theory about our Asian relative, the orangutan, who has shown solitary behavior. The conclusion of these two theories is that the social or solitary behaviors of the species will depend, among other reasons, on the environmental circumstances of each species.

Sociality, as it was mentioned above, helps to avoid predators. However, it also benefits the group against hostile neighbors from the same species. In chimps, for example, the hostilities are among communities. The males invade neighboring communities, they kill the offspring of females whom have not been their mates, and sometimes they also kill the adult males. If the males of the attacked community develop social tendencies to defend themselves, they and their kin will have more survival and reproductive possibilities in the future.


Social Life in the EEA

The author states that we can find out what life was like in the EEA by studying modern hunter-gatherers. He says that although they are completely modern people, they still face the same basic ecological constraints as did our ancestors, the main one being that they, too, must forage for food (both game and plants). Because they lack cultivated crops and domesticated animals, there are very low limits placed on the size of their communities. The author goes on to say that contemporary foragers exist in small groups that are semi-nomadic. These groups range in size from ten to thirty people and individuals or families are free to move from one group to another if opportunities are better elsewhere. These local groups add up to a small community of a few hundred people in which most know each other. There is a good chance that an individual will never run into a "stranger" and there is a strong sense of kinship.


The Role of Reciprocity in Human Social Behavior


Reciprocity is an alternative to altruism but there is a model called reciprocal altruism, in which one is altruistic to another altruist but then withhold altruism from cheaters. The author cited an experiment done by Yinon and Dovrat (1987) that involves a "wrong-number technique," followed by a request for help. The experimenter dials a random number. When someone answers, he tells the person that he dialed wrong but has no more money to make another call and he needs to get an urgent message to his wife. He invents a fictitious crisis and asks the person to give the message to his wife. The author states that in this experiment, "cost, benefit and reciprocity potential were varied systematically". Cost was varied because he kept the wife's phone line busy for a long time, benefit varied by alterations of the story, and reciprocity potential was varied because of the fictitiousness of the story. The results of the experiment showed that "help is more likely to be given when the cost is low, the need is more urgent, and the requestor has a high potential to reciprocate."

The author cites another experiment done by Greenberg and Shapiro (1971) in which " a pair of subjects could earn money by reaching, and more money by exceeding, a quota on two tasks." But one of the two subjects in each pair was not actually a real subject, but was put in the experiment by the experimenter to influence the results. In the first stage, the experimenter made it look like the real subjects would not meet the quota and the fake subjects would. In the second stage the experimenter made it look like all the real subjects would make the quota and for half of them their partner would not make it and for the other half their partner would. The purpose of this experiment was to see if the real subjects would help their partner if their partner needed it. The results were that some of the real subjects needed help themselves and would only give help if they could receive help in return and some subjects who needed help would not ask for it unless they were able to give it in return.


Cognitive Implications of Selection for Reciprocity


Robert Trivers in 1971 postulated that liking and disliking are an evolutionary adaptation that allows us to form relationships with those people that are willing to reciprocate. We feel gratitude in relation to the altruism in the actions we feel guilty when we don't reciprocate the altruistic behavior. Since we prefer to relate to people who might reciprocate our emotions and actions, cheaters would be avoided. There are several studies investigating behaviors with cheaters. Linda Mealey found that people who are thought of as cheaters are remembered significantly more than those who have a positive or neutral label. In her study photographs were shown and paired with a story depicting the person's character, some were cheaters, others were more positive. A week later, the participants were shown twice as many photos and were asked which were remembered.

Robert Frank et al (1993) found that after short interactions, subjects were able to tell whether an opponent was going to cooperate or cheat. This demonstrates that people have the ability to recognize whether or not a new acquaintance will be a reciprocator or a cheater. This allows people to "minimize the amount of altruism they waste on individuals who are never going to reciprocate." Surprisingly almost 75% of the participants chose to cooperate rather than cheat. This is interesting because they knew the payoff matrix (Table1) and cheating would have been the best strategy. Another example of this game theory example is ultimatum games. In this "game" subjects are forced to divide ten dollars which will be acceptable for the other player. If the other player rejects the offer, they both get nothing. The best strategy would be to offer one dollar and keep nine, after all if the other player rejects the offer they will get nothing. But most participants divided the ten dollars evenly, five and five. A variation of this game is to eliminate the possibility of rejection. The subjects were now told to name a division of the cash with no say from the other participant. This "dictator game" reduced people's niceness. Another explanation of why people are so generous in the game is that they are trying to protect their reputation, and therefore reciprocating altruism. The experiment was then performed "double-blind", neither the experimenter nor the subjects knew the proposal. Although this also considerably reduced niceness, the participants still did not keep all the benefits to themselves. The authors explain this by concluding that it is impossible for people to act completely selfish "because people are designed to operate in a world of repeated interactions" we protect our reputations as reciprocators.


Reciprocity and the Environment

Human behavior is implicated through environmental problems that are, according to Luce and Raiffa, "prisoner's dilemmas" (p. 335). Hardin (1964), created an example of this that he called, "the tragedy of the commons" (p. 336). It is a game in which the players share a grazing ground called the "commons." The players in this game take on the role of the herders. In order to remain silent, as Hardin (1964) portrayed, the players must keep their herds small on the "commons," for if they don't, the game is being cheated. For example, if a herder adds another animal to the grazing ground, he has broken the pack, therefore confessing to not doing his part to keep the herd small. There are pros and cons to this and these exemplify the point. The pros of increasing the herd size for a particular player are, receiving payment of this additional animal, for example by it being sold or by it's products being bought (e.g. milk). Thus, the payoff for this animal belongs to him and only him, therefore the player will want to do this because his benefits outweigh his costs. However, the cons include overgrazing and reduction of value for the rest of the animals. So in the long run, if one herder is too add an animal to the original herd, there will be a desire for all other herders to copy this act to benefit personally as well. This, in turn, will decrease the "commons" value, every animal's value, and profit will thus diminish. Hardin's (1964) example demonstrates "Prisoner's Dilemma;" "when each person chooses his/her most rational alternative each ends up worse off than if he/she cooperated" (p. 337). This point includes the alleged cheaters of today's society. Most of society takes the convenient alternative, thus the costs increase for everyone. However, Trivers (1971) recognized that, "altruism can spread if and only if it is with held form non-reciprocators" (p. 337), thus benefits are held from cheaters. The conclusion is society id designed to be altruistic; for cheaters have been discriminated against throughout evolution. Thus, the point being, cheaters should continue being punished and cooperators rewarded, not allowing cheaters to create a slippery slope effect.


The Role of Status and Dominance in Social Life


People in hunting-gathering societies, like people in today's societies had status and differences in rank. However, unlike people today who acquire status through wealth, the hunter-gatherers accumulated status through skills, strength, experience, knowledge, etc. Rank is common across all species and is known to provoke different modifications of behavior. An example of this is modifying one's behavior when meeting a person with high rank/status. Hunter-gathering societies would have modified their behavior by recognizing who killed the most animals for meat and that person would be of the highest status. The differences in behavior would easily be recognized in today's society; those with higher ranks don't expand their notions of others, whereas lower ranks spend more time recognizing details of others above them.









Table 1 Payoff Matrix for Frank's Prisoners Dilemma Game









$2 for other player

$2 for you

$3 for other player

$0 for you


$0 for other player

$3 for you

$1 for other player

$1 for you








I.                    Why Be Social

1.      Socialization: interaction and/or association among members of the same specie.

2.      Social Behavior if benefit the species, it will be repeated. If Social behavior produces more costs than benefits, solitary behavior will be adopted.

3.      Social behavior favors predator avoidance and food acquisition therefore it favors survival and reproduction of the species.

4.      Socialization is a key factor for adaptation and survival.

II.                 Selection pressures favoring Human Sociality

1.      Human societies are more successful than solitary humans.

2.      Food resources, predator avoidance, and hostile neighbors are better coped by societies than by solitary species.

III.               Social life in the EEA

A.     Information about our ancestor's social lives can be found by studying modern hunter-gatherers.

1.      Both had to forage for food so faced similar ecological constraints.

2.      Groups range in size from 10-30 people.

3.      Membership in these groups is fluid.

4.      Strong sense of kinship.

IV.              The Role of Reciprocity

A.     Model of Reciprocal Altruism

B.     Two experiments:

1.      "Wrong-number technique".

2.      Meeting the quota.

V.                 Cognitive Imiplications of Selection for Reciprocity

A.     Cheaters

1.      Recognizing cheating and recognizing individuals already explained as evolutionary adaptations

2.      Linda Mealey et. al. (1996)

a.       cheaters remembered more than other characters

b.      demonstrate that personalities affects recollection

B.     Non-reciprocators

1.      Reciprocator vs. Cheater

2.      Cheaters recognized in advance

C.     Suprisingly Altruistic

1.      Prisoners' Dilemma

2.      "Ultimatum Games"

a.       vs. dictator games

b.      double blind

VI.              Hardin's (1964), "the tragedy of the commons"

A.     The Game

B.     Costs and Benefits

C.     His point

VII.            Status and Rank

A.     Hunter-Gathering societies

B.     Animals

1.      Chickens

C.     Today's society

D.     Modifying one's behavior