Session 16: Cooperation and Competition

1.  Key Concepts:

2.  Terms & Definitions:

Competition

The struggle among organisms, both of the same and of different species, for food, space, and other vital requirements.

Cooperation

Mutually beneficial interaction among organisms living in a limited area.

Affiliation

A social relationship; to become closely connected or associated.

Agonism

The broadest spectrum definition of aggression, from negative interactions to extreme physical contact.

3.  New Perspectives on Costs and Benefits of Group Living:

Richard Wrangham's model of costs and benefits of group living focuses on feeding competition as the core to group dynamics, including the moderation of aggression and affiliative interactions.  This feeding competition is critical in limiting females, which then, in turn, limits males.  Two variants of this model have been proposed:

• Socioecological model: feeding competition directly.
  
• Ecological constraints model:  travel costs in addition to feeding costs.

However, according to Sussman & Garber:

• Agonism occurs at very low frequencies among diurnal primates living in the same social group. This does not fit the predictions of the Socioecological Model.
• Agonism at feeding sites does not occur more frequently among female primates that form linear dominance hierarchies than among females that form egalitarian social relationships. This does not fit the Feeding Competition Model.
• Individuals in larger groups of primates do not necessarily travel greater distances than individuals of the same species living in smaller groups. This does not fit the Ecological Constraints Model.

• In those cases when individuals in larger groups experience increased travel, the energetic cost of travel for arboreal or terrestrial primates is expected to be relatively low.   This does not fit the Ecological Constraints Model.

So…

• Resources in tropical forests are found in dispersed, hetergeneous patches.
• Primates are characterized by tremendous dietary breadth in the types of foods exploited.
• In many primate taxa, grouping patterns are highly flexible and individuals may form subgroups as a facultative response to local ecological and social conditions.

• There are reasons to suggest that groups in a population are commonly below their maximum size, and therefore the effects of feeding competition are expected to be low across a range of group sizes.
• However, group size is not necessarily related to the quality of resources within a home range or that feeding competition is not a factor in primate behavioral ecology and individual fitness.
• Rather than feeding competition being expected to play a minimal role in primate social interactions, in large groups it is likely to result in an increase in short-term rates of agonism and eventual fissioning. 

• If the costs of feeding competition and group living are less than previously thought, then researchers need to focus on the benefits of affiliation, co-operation, and mutualism in understanding the evolution of primate sociality.

Cooperation and mutualism are important:

Primates have internal neuroendocrine stimulation that allows us to receive stimulation from observing others receiving positive stimulation.  Primate physiology can support cooperative behavior.  Cooperation and affiliation is more likely to be a strategy for success, not necessarily a strategy to avoid conflict.

4.  Additional Material:

Primates in Perspective.  2007.  C.J. Campbell, A. Fuentes, K.C. MacKinnon, M. Panger, S.K. Bearder.  Oxford University Press.

Chapter 39: Cooperation and Competition in Primate Social Interactions - Sussman and Garber