Intra-group Coalitions/Alliances

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Human Uniqueness Compared to "Great Apes": 
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Intra-group coalitions are temporary multi-party groups that act cooperatively in competitive or aggressive contexts against at least one other individual or unit. These are related to alliances, which are coalitions that form on a regular basis. Coalitions are not unique to humans; they are found in a wide range of social mammals. However, humans are likely unique in the number and scale of coalitions maintained by any one individual, as well as in the practices used to mediate coalitions and in the functional achievements of such groups.



Timing of appearance of the difference in the Hominin Lineage as a defined date or a lineage separation event. The point in time associated with lineage separation events may change in the future as the scientific community agrees upon better time estimates. Lineage separation events are defined in 2017 as:

  • the Last Common Ancestor (LCA) of humans and old world monkeys was 25,000 - 30,000 thousand (25 - 30 million) years ago
  • the Last Common Ancestor (LCA) of humans and chimpanzees was 6,000 - 8,000 thousand (6 - 8 million) years ago
  • the emergence of the genus Homo was 2,000 thousand (2 million) years ago
  • the Last Common Ancestor (LCA) of humans and neanderthals was 500 thousand years ago
  • the common ancestor of modern humans was 100 - 300 thousand years ago

Possible Appearance (Lineage Separation Event): 
Probable Appearance (Lineage Separation Event): 
Background Information: 

A coalition is a temporary multi-party group that acts cooperatively in competitive or aggressive contexts against at least one other individual or unit. These are related to alliances, which are coalitions that form on a regular basis. An intra-group coalition is formed from within a stable social group, and can be comprised of kin or non-kin. As noted by Harcourt and de Waal (ibid), the presence of coalitions represent a paradoxical relationship in which the evolution of cooperation likely emerged as an offshoot of competitive and aggressive tendencies. The variation in social structures as well as the presence of levels of alliance formation mean that the word “group” is relative. For this discussion, “group” will refer to a network of individuals who rest and travel together for a significant portion of the year (≥ 1 season), and among humans, share the same dialect. Among social mammals, coalitions form in the contexts of dominance and resource competition. They have been observed among many species of primates as well as among lions (Panthera leo), cheetahs (Acinonyx jubatus), coitis (Nasura narica), wolves (Canis lupus), spotted hyenas, and bottlenose dolphins. Coalitions mediate reproductive success among males and females by influencing rank relations, access to female mates, siring offspring, territory, and food. Differences in fitness return curves for mating effort and parental effort lead to differences in the way that males and females form coalitions. Among females, parental effort coalitions are more likely. Among males, coalitions are often directly or indirectly related to mating effort. Female alliances usually occur in contests over resources that the victors can share.

The Human Difference: 

While both humans and great apes form coalitions and alliances with one another, there are differences in the level of complexity and the scale at which these are formed. Humans form coalitions at all levels, from two individuals all the way up to the state and country level. Friendships, cliques, gangs, syndicates, cartels, political parties, governments, and international partnerships are all examples of coalition formation among humans, and any one human may be involved in multiple coalitions at any one time. Apes form coalitions at the individual and local group level only. To date, there are no reported inter-group alliances among wild apes. While almost all humans form alliances with conspecifics, not all great apes have been observed to form coalitions. For the remainder of this topic we will restrict examples of human coalition formation to those kinds that may have been present in Holocene ancestors. --Male/female differences-- As with other mammals, in pre-industrial societies and likely among our Holocene ancestors, differences in fitness return curves for mating effort and parental effort lead to differences in the way that males and females form coalitions. Among females, parental effort coalitions are more likely. Among males, coalitions are often directly or indirectly related to mating effort. Female-female coalitions are often household based, forming among sisters and co-wives. These coalitions function in cooperative breeding, as well as in the exchange of information about foraging locations and techniques (Low 1992, Irons 1983). Women have considerable control or influence over resources, but are rarely found as major political figures within pre-industrial societies. In these cases, political power is often matrilineal or double descent; systems predicted to enhance the reproductive success of male offspring. In the societies where females hold significant power, it appears that male-female coalitions may be a more suitable description. Among the Ashanti people of north west Africa, power was held by the “Queen Mother” and the chief. The Queen mother’s veto could not be overruled and had considerable influence over alliance formation, but she was barred from attending court while menstruating and going to war until post-menopausal. By far the most numerous examples of coalition formation among humans are male-male. Thus Navarrete and McDonald (2014) note, “intergroup aggression has almost exclusively been perpetrated by groups of males against other males in contexts ranging from small-scale coalitional skirmishes to regional and geopolitical conflicts.” The following discussion focuses on the organization and function of male-male intra-group coalitions. --Organization of intra-group alliances-- Within groups, coalitions organize based on kinship, age, and politics. Among the Yąnomamö (S. America, Amazonia), kinship, group membership, and intra-group alliance membership are closely linked. Similarly, Sahlins (1963) describing the structure of Melanesian society writes, “The rising big-man necessarily depends initially on a small core of followers, principally his own household and his closest relatives. Upon these people he can prevail economically: he capitalizes in the first instance on kinship dues and by finessing the relation of reciprocity appropriate among close kinsmen…Each new marriage…creates for the big-man an additional set of in-laws from whom he can exact economic favors. Finally, a leader’s career sustains its upward climb when he is able to link other men and their families to his faction, harnessing their production to his ambition. This is done by calculated generosities… a common technique is payment of bride wealth on behalf of young men seeking wives.” Similarly, in addition to contributing to the cultural development of young men, the bachelor’s cults (sangai) of central and western Enga Province contributed to bride wealth payment of young men who had been through their ritual and deemed mature. These cults “…gave older men control over the younger generation, instilling desired values & brewing loyalties that made it possible to form larger coordinated fighting forces." Payment of bride wealth is an interesting phenomenon in which alliances are established through financial contributions to male reproductive success. More ape-like behavior is also seen; for example Chagnon (1988) reports that “aggressive groups [of Yanomamo males] coerce nubile females from less aggressive groups whenever the opportunity arises.” The Turkana people of north west Kenya are nomadic pastoralists whose social organization might have otherwise be described as atomistic if not for their fascinating method of coalition formation. At birth, all men are assigned to one of two alternations (stone or leopard) opposite of their father’s. Additionally, in pre-conquest Turkana society youths (14-20y) were initiated into an age-group at different ceremonial sites across the region. The age group defined the rules of social engagement such as where to sit and what role to take on during feasts. In warfare, a combination of alternation and age-group organized the warring party (whose constituents may include strangers) into a two-column formation (separated by alternation) and roles (defined by relative age-group). The Ache foragers of eastern Paraguay engage in cooperative foraging. The whole band starts off together before the men depart to search in pairs or small groups. They call other men over to help when large prey are found. In any given day, the probability that a hunter would not kill any game was 40%. But, the community acts cooperatively, sharing game almost equally to all families & individuals who participated in the attempt to acquire resources. Food sharing is another way in which alliances of individuals may be mediated. --Function of intra-group alliances-- A major function of coalitions is to compete with other groups over resources. Among the Enga of Papua New Guinea, before the introduction of the sweet potato, wars were triggered by theft of game from traps, quarrels over possessions, or work sharing within the group. During these fights, “ ‘brothers’ with strong loyalties came to each other’s rescue."  Among the Turkana, raids were undertaken to acquire cattle from neighboring ethnic groups, increase access to grazing areas and crucial dry-season watering holes. Raids took one of two forms: stealth raids involving few (12 on average) men who stole poorly guarded livestock, and force raids involving many (average 248) men who engaged in combat. Revenge killing is widespread among pre-industrial groups, and may involve kin or non kin. It has been reported, for example, among the Ache, Yanomamo, Enga, and Turkana. Among the Turkana and Yanomamo, retaliatory raids are believed among to produce deterrence, trading immediate risk for future safety. Among the Yanomamo, Changnon (ibid) reported that many fights began over sexual issues, the outcome relying on the mans’ skills and the support of his close kin. In such interactions, yet another function of alliances is risk management. Navarrete and McDonald (2014), write “the formation of alliances is typically characterized by mechanisms for effective risk management, such as pooling risk across individuals behind a ‘veil of ignorance’ regarding one’s probability of injury or death, and ‘winner take all’ outcomes that create large payoffs for survivors.” Similarly, Chagnon (1988) notes “in the context of threats or coercion by others or of potentially violent encounters, group members cooperate for mutual protection and use their collective skills and abilities to this end, including the capacities of group members to act violently if necessary.” Low (1992) notes that “cross-culturally… a pattern is apparent of men forming coalitions to gain resouces, and using resources to gain reproductively.” In addition to wealth via pigs or livestock, males also gain status by participating in revenge killings and raids. Among the Yanamoma, Chagnon (1988) reports that men who are killers may gain marital and reproductive benefits. Among the Turkana, Gulliver (1958) indicated that new age-groups should go on raid as soon as possible, as a point of honor. This likely plays a role in future discussions with intended’s father and seeks the support of age-mates in marriage and bride wealth discussions. However, not all killers (perhaps not all kills) are honored. Hill (2014) noted that a male who had killed his wife never took another wife or reproduced. Finally, an important role of alliances is likely in the acquisition of power in hierarchical societies, as indicated by the discussion of rank ascension among the “Big-Man” among Melanesian tribes above. --Group identification / Coalition signaling-- Humans may be unique as well in their form of coalition signaling. Human coalitions and groups may be distinguished by Tattoos, Dance & Music, as well as style of tools and weaponry.

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