January 25, 2005

Ecological dominance, social competition

This paper examines Richard Alexander's model of "ecological dominance, social competition" as the explanation for the develoment of human intelligence. According to this model, our ancestors' mastery of the "forces of nature", or ecological dominance triggered a process of social competition. Unlike other animals whose fitness is determined by whether they can survive in nature, humans tamed their environment, and thus their fitness started being determined by how well they could socially compete with other humans. This transfer of emphasis from nature to society is the distinguishing feature of our lineage, and it can explain the complete departure of human cognitive ability from that of our hominin ancestors.

Evolution and Human Behavior
Volume 26, Issue 1 , January 2005, Pages 10-46

Ecological dominance, social competition, and coalitionary arms races
Why humans evolved extraordinary intelligence

Mark V. Flinn et al.


Human cognitive abilities are extraordinary. Our large brains are significantly modified from those of our closest relatives, suggesting a history of intense natural selection. The conditions favoring the evolution of human cognitive adaptations, however, remain an enigma. Hypotheses based on traditional ecological demands, such as hunting or climatic variability, have not provided satisfying explanations. Recent models based on social problem solving linked with ecological conditions offer more convincing scenarios. But it has proven difficult to identify a set of selective pressures that would have been sufficiently unique to the hominin lineage. What was so special about the evolutionary environments of our ancestors that caused them, and them alone, to diverge in such astonishing ways from their close relatives and all other life forms? Richard Alexander proposed a comprehensive integrated explanation. He argued that as our hominin ancestors became increasing able to master the traditional “hostile forces of nature,” selective pressures resulting from competition among conspecifics became increasingly important, particularly in regard to social competencies. Given the precondition of competition among kin- and reciprocity-based coalitions (shared with chimpanzees), an autocatalytic social arms race was initiated, which eventually resulted in the unusual collection of traits characteristic of the human species, such as concealed ovulation, extensive biparental care, complex sociality, and an extraordinary collection of cognitive abilities. We term this scenario the “ecological dominance–social competition” (EDSC) model and assess the feasibility of this model in light of recent developments in paleoanthropology, cognitive psychology, and neurobiology. We conclude that although strong or direct tests are difficult with current data, Alexander's model provides a far-reaching and integrative explanation for the evolution of human cognitive abilities that is consistent with evidence from a wide range of disciplines.



  1. Ever since Robert Ardrey's book The Territorial Imperative there have been attempts to show that our own ancestral species, such as the Australopithicines, must have been territorial.

    But there has been enough research into the way land is used and conceptualized among hunting and gathering peoples to call this assumption into question.

    You get reciprocal access, a close companion in the survival handbook of the hunter-gatherer, with the phenomenon of generalized reciprocity.

    I have no reason to try to deny that humans are capable of murder and warfare but does this mean these are part of a species-specific behavioural algorithm?

    Alexander's "autocatalytic social arms race" was not gangs of guys beating each other to a pulp to take away territory. It was the whole cultural system, and the way people had to keep track of it all and deal in the most efficient (smartest) way with competition and other cultural groups.

    "Human groups also tend to be male philopatric, resulting in extensive male kin alliances, useful for competing against other groups of male kin..."

    Why, while taking all this trouble to be accurate over minute details of neural functioning, did they not go to the appropriate ethnographic literature and brush up on hunter-gatherers?

    Hunter-gatherers are usually bilateral in terms of kinship reckoning, although some are patrilineal and some are matrilineal. Many hunter-gatherers have a pattern of matrilocal post-marital residence, a few have patrilocal, and some are neolocal.

    And what the heck is a mere tendency doing in this discussion? We are not trying to explain the tendency for human brains to have a special region for Theory of MInd, or Empathy. We are not discussing a tendency for human infants to altricial, or for human females to experience menopause.

    The only thing I can think of is that they have placed a lot more emphasis on male coalitions formed - primarily among male kinsman- for the purpose of war, front and centre in their own minds as a mechanism explaining why we became human at all.

    The only reason, as far as I can see, why they would risk doing this is because they are seriously suggesting that humans have been forming gangs to beat up guys from other (competing, supposedly) communities AS A MAIN STRATEGY ever since we parted company with the line leading to Pan troglodytes.

    The hypothesis that is suggested here is NOT supported by all the known data from ethnography and primatology. It still needs work.
    Regards, Helga

  2. They state authoritatively that "No other primate that lives in large, cooperative multiple-reproductive-male groups has extensive male parental care, although some male protection is evident in Papio (Buchan et al., 2003)." This is incorrect. Sex ratios in the Gibraltar Ape - actually a macaque -Macaca sylvanus - are fairly even, with many adult males resident within a troop. Females mate with all the adult males in the troop. Males are frequently seen involved in parenting, including carrying the infants for extended periods during the day and teaching them to walk. This has been known since the 1970's through the research of Frances Burton and her students. Sarah Hrdy, a scholar who has also written on this subject in other primates, even goes so far as to suggest that promiscuous mating helps to promote this kind of male parental involvement since no male can be sure any infant is NOT his.


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