symbiotic organisms

Some legume plants, which rely on beneficial soil bacteria called rhizobia that infect their roots and provide nitrogen, seem to promote cooperation by exacting a toll on those bacterial strains that don't hold up their end of the symbiotic bargain. "In the case of soybeans, it appears that the plant applies sanctions against rhizobia that don't provide nitrogen. The plant does this by decreasing the oxygen supply to the rhizobia. In this way, the host plant can control the environment of the symbiotic bacteria to favor the evolution of cooperation by ensuring that bacterial 'cheaters' reproduce less." >from *Cooperation is a no-brainer for symbiotic bacteria*. September 4, 2003

network dynamics organize social structures

The ability of certain animals to form complex social systems -- particularly humans and social insects -- is considered by many biologists to be one of the pinnacles of biological adaptation and complexity. Social organization allows organisms to share labor, to specialize in tasks and to coordinate efforts. Through organization, social animals accomplish remarkable things... Network dynamics can create organized social structures when relatively simple connections between various individuals in a group create patterns of behavior of increasing complexity, much the same way as relatively simple mathematical rules can create mathematical patterns of great intricacy. >from *Social insects point to non-genetic origins of societies. Social structures form through group dynamics, not trait selection*. September 4, 2003

cooperation evolution: inequity aversion

During the evolution of cooperation, it may have become worthwhile for individuals to compare their own payoffs to those of others, in an effort to increase relative fitness. Humans do so, frequently rejecting payoffs that are perceived as unfair (even if they are advantageous). While there is some variation, this response is widespread across human populations. If a sense of fairness did evolve to promote cooperation, some nonhuman animals may exhibit inequity aversion as well. This is particularly likely in social species with tolerant societies, such that individuals may reasonably expect some equity between themselves and other group members. Identifying similar reactions in nonhuman primates as in humans offers insight into how such emotional reactions developed, providing researchers and economists new perspective on why humans make certain economic decisions in relation to efforts, gains and losses of others. >from *Yerkes researchers first to recognize sense of fairness in nonhuman primates. Findings shed light on the role of emotion in human economic interactions*. September 17, 2003

related context
> commons-based peer production in the digitally networked environment. december 19, 2002
> neurophysiology of sympathy: patterns of brain activity. december 10, 2002
> human cooperation: biological basis revealed. july 19, 2002
> cooperation and affiliation: primary social behavior in primates. february 25, 2002

imago
> symbiotic bargain process: toll free?