Biology Essay

What is the evidence that some human behaviour has evolved to serve the wider group, rather than just serve individuals or their immediate families?

`Ask not what your country can do for you, but what you can do for your country` was famously proclaimed by J.F.Kennedy in his 1961 inaugural address (Cartwright,2008,p.207). Performing behaviours benefiting the group instead of the individual`s genome poses interesting questions for sociobiologists, these altruistic behaviours seem inconsistent with widely accepted evolutionary theory. Darwin proposed species evolve by adapting to their environment through mechanisms of natural selection; this theory has been expanded by modern scientific knowledge to acknowledge the gene as the unit of natural selection. For most of humanity's evolutionary history humans have been subject to the same selection pressures and mechanisms as other animals - like kin selection observable in animal species, human evolution of altruism for the benefit of the group must have a biologically sound explanation (Barret,2002). This essay aims to examine the theoretical explanations sociobiologists have proposed to address the evolution of human behaviours benefiting the group over the individual, as well as the role communication and punishment mechanisms play in these behaviours. Social phenomena relevant to group fitness such as food-sharing, cooperation and homosexuality will be explored in order to gain a broader understanding of the evolution of behaviours for the benefit of the group.

Group selection The evolution of some human behaviours serving the wider group are thought to be adaptations to resolve, in part, the Tragedy of the Commons described by the ecologist Hardin: the conflict between individual benefit in maximising one`s personal resources, and the overall cost to the group if this is carried out(1968, as cited in Krebs,1993). Cooperative behaviour by individual members of a group is present to a greater or lesser extent in all human populations. Kinship can explain some of the high proportion of cooperation, but not in all cases. Sociobiologists suggest humans are selected for sociality, raising the question if this behaviour evolved by cultural or genetic selection. More recently, the false dichotomy postulated by this nature-nurture debate has been replaced by an approach where gene-culture co-evolution is considered(Barret,2002). Research by Soltis et al. explored the concept of cultural behavioural differences driving preferential group-selection, hence shedding some light on how the human evolution of altruistic behaviour might be explained. The research focused on group-selection amongst pre-state societies in Papua New Guinea as these best represent ancestral human populations. The spread of innovations amongst group members led to the conclusion that cultural group selection can explain the evolution of group-functional behaviours, as long as between-group variation is maintained, and group selection occurs with sufficient rapidity(Soltis et al.,1995). In this way, cultural group selection is postulated as selecting cooperative psychological traits within groups, regardless of relatedness amongst members . We can see this is evidence for some human behaviours evolving to benefit the group as a whole, through preferential selection for groups whose members cooperate successfully. The greatest threat to our hominin ancestors may have been `the existence of other hominin groups tightly bound in a system of mutualistic cooperation and willing to instigate violent conflict`(Cartwright,2008,p.205).

Reciprocal altruism A study was conducted examining the sharing of information of lobster location in different sized harbours. This valued information was shared more readily in small harbours with closer community ties, where group members were stable. This was described as reciprocal altruism by sociobiologist Trivers, who suggested altruism need not be reciprocated directly by receiver, but from other individuals or even society as a whole. Gaining a good altruistic reputation means other group members will act more favourably towards one, increasing one`s social status and therefore indirectly increasing individual fitness(1971,as cited by Barret,2002). Research by Noë and Hammerstein developed the notion of biological markets within groups, where good reciprocators preferentially interact with each other. Cheats and exploitative individuals are ostracised, effectively maximising the number of individuals with in-group reasoning(1995,as cited by Barret,2002). As we have seen, food-sharing is a good example of humans acting for the benefit of the group. This behaviour is widespread amongst hunter-gatherers, where reciprocal sharing ensures a more steady supply of protein-rich food. Nutrition does not seem to be the only benefit at stake however: research by Hames found a correlation between the riskiness of food type acquisition and the frequency of food exchange between households. Successful hunters are believed to share as this is an effective way of gaining benefits unrelated to foraging, such as a higher status(1990,as cited by Barret,2002). Evolutionary psychologist Alexander suggests performing costly acts in order to gain a reputation may often motivate people`s behaviours. Some individuals, generally young men, do worse by sharing their resources then they would by keeping them. It is true to say these individuals stand to gain the most from increasing their reputation in the long-term, with a clear effect on their success in female mate choice. The implication of this is such that men are driven to hunt not to ensure regular food supply for the individual`s immediate family, but sharing and ultimately for sexual motives(1979,as cited by Barret,2002). Hawkes uses evidence from the Ache in Paraguay to support the argument that social attention granted to high providers is a powerful motivation for group-benefiting behaviour, as it provides individuals with a larger pool of potential mates and allies. This seemingly altruistic behaviour effectively amounts to delayed reciprocity within the group(1993,as cited by Barret,2002).

Cooperating Sociobiologists have raised the question of whether humans are inherently selfish or not. As suggested by reciprocal altruism, the motivation to perform behaviours for the group is thought to have developed as it increases the individual`s fitness in other ways. Sociologist Mulcahy for example, found that men in the early stages of a relationship are much more likely to give to beggars, believed to be trying to convey the impression they are altruistic(1999,as cited by Barret,2002). Importantly, this sheds light on the attractive value of altruistic behaviour, as it highlights women may hold this trait in high regard, perhaps as a marker of resource wealth in the man. Hawkes describes these human behaviours as `in a manner consistent with a system of enlightened self-interest, rather than in a truly altruistic fashion`(1993,as cited by Barret,2002,p.86). Others have refuted this notion, stating there is evidence humans can act as true altruists, absent of any selfish motivations. Caporael et al. gave participants $5 each and told them to choose anonymously how much to contribute to a common pool. If enough money was contributed then each would receive a $10 bonus, regardless of how much the individual contributed. Although a $0 contribution would have been the optimal individual strategy, more people than expected contributed to the pool. This was increased when participants were allowed to interact before experiment, even though contributions were still anonymous (1989,as cited by Barret,2002). This suggests sociality itself may be evolved to promote sharing behaviour, as a mechanism of driving group cohesion. Benefits of group-living would favour people better adapted to group-living, in the form of willingness to cooperate for the good of the group independently of either receiving a direct reciprocal benefit from the beneficiary of altruism, or enhancing the spread of their genes by helping close relatives. Critiques of this experiment state it does not disprove egoistic incentives, as participants had nothing to lose and may have been under strong demand characteristics to behave in order to impress the examiners. Experimenters were unable to create a situation which completely eliminates egoistic incentives. However, in human populations, each individual`s fitness is ultimately dependent on the group solving common problems effectively. If behaving `altruistically` benefits our selfish genes, these behaviours will be selected for(Barret,2002). Another interesting example of evolution of human behaviours for group cooperation is in homosexuality. Darwinian views of natural selection based on reproductive success suggest homosexuality should become extinct; in reality it is widespread in time and geography, posing a puzzle for evolutionary sociobiologists. Literature by Kirkpatrick highlights sexual behaviour and emotion can serve a non-conceptive function, such as formation and maintenance of same-sex alliances. These can maximise cooperative behaviours such as defence, helping in resource competition. `Homosexual behaviour is not at a selective disadvantage as long as enough heterosexual matings ultimately occur, on average, to provide the individual with the average number of surviving offspring`(Kirkpatrick,2000,p.396). The overall group benefit is suggested to place homosexuality under positive selection and therefore to evolve as part of human group-functional behaviour (Kirkpatrick,2000).

Dealing with defectors There is evidence humans have evolved an innate sense of fairness. The Ultimatum Game involves individuals making a one-off offer for a share of resource. If the other declines, both receive nothing. Offers are consistently between 45-50%, although an offer of 1% should be rationally accepted. These figures are representative of western societies and therefore lack some cultural validity; in non-western and hunter-gatherer populations offers are around 20%, still substantially higher than 1%(Barret,2002). `It will always pay at least a proportion of individuals to cheat all the time` (Barret,2002,p.76). If humans participate in group-benefiting behaviours, how do they ensure free-riders and cheats don`t hog all the benefits of this? A study by Fehr et al. showed altruistic punishment aided cooperation, where negative emotions towards defectors are a proximate mechanism for punishment. Researchers devised an experiment similar to Caporael`s (1989), with the additional choice for participants to punish individuals once contributions had been made, at a cost. Truly selfish individuals would neither cooperate or punish as both are costly and neither yields financial benefits. It was found, however, that altruistic punishments took place frequently. Defectors were punished by contributors, where punishment substantially increased the amount participants contributed: 77.8% contributed three-quarters of their resource. In the non-punishment condition, contributions fell sharply, with over 50% contributing nothing. Experimenters concluded that the threat of punishment was an effective deterrent, as most people are aware they trigger strong negative emotions in others when they free-ride(Fehr,2002). This illustrates humans are `good reciprocal altruists and cooperators among our circle of acquaintances, but people need more coercive measures to avoid defecting and dropping the cost onto a wider anonymous group` Cartwright (2008,p.207). Research by Nowak and Sigmund found altruism spread through populations where individuals were not likely to encounter each other again, as long as they could observe altruism in others(1998, as cited by Cartwright,2008). This positive feedback system suggests communication between group individuals promotes cooperation, allowing cooperation to evolve as an evolutionarily stable strategy. Humans have therefore evolved a strong in-group bias, favouring individuals from their own group as a psychological adaptation promoting group-living. Boyd and Richardson describe humanity's ultra-sociality as a combination of ancient social instincts and modern cultural institutions allowing impressive coordination, cooperation and division of labour observed in most modern-day societies (1998,as cited by Barret,2002). In psycho-somatic terms, our bodies have evolved ingenious ways of promoting group-benefiting behaviours. Buck (2007) explains cooperative tendencies are experienced as neurochemical signals in the brain, creating associations between powerful emotions and altruistic social behaviours. These `somatic markers` play important roles when making decisions: we feel pleasure at our actions being approved by others, and shame or guilt when they are not(Damasio,1994, as cited by Barret, 2002).

This essay examined the theoretical basis of sociobiological explanations for group-benefiting behaviours in humans. Although there are numerous examples of humans acting altruistically, a closer analysis suggests these behaviours do tend to benefit the individual in some way, often indirectly. Barret proposes `individuals are capable of true altruism and yet achieve high fitness returns by doing so, not because they have `overcome` our genes, but because true cooperation was originally to their benefit`(2002,p.91). The importance of mechanisms promoting in-group mentality, such as altruistic punishment and communication indicates how some human behaviours have developed to benefit the group over the individual. Unlike kin selection, group-directed behaviours benefit the individual in complicated and often indirect ways. Humans seem hard-wired to cooperate: `motivating our selfless actions by rewarding us with that glow of self-satisfaction may well be the cleverest trick evolutionary psychology has yet played on us`(Walton, 2004,p.229). Group cooperation forms the glue for our sociality, a fundamental part of what it means to be human.