Understanding how cooperation evolves and is maintained represents one of evolutionary biology's thorniest problems. This stems from the fact that freeloading cheats will evolve to exploit any cooperative group that doesn't defend itself, leading to the breakdown of cooperation. New research using the bacterium Pseudomonas fluorescens has identified a novel mechanism that thwarts the evolution of cheats and broadens our understanding of how cooperation might be maintained in nature and human societies. The new findings are reported by Michael Brockhurst of the University of Liverpool and colleagues at the Université Montpellier and the University of Oxford.

Bacteria are known to cooperate in a wide variety of ways, including the formation of multicellular structures called biofilms. P. fluorescens biofilms are formed when individual cells overproduce a polymer that sticks the cells together, allowing the colonization of liquid surfaces. While production of the polymer is metabolically costly to individual cells, the biofilm group benefits from the increased access to oxygen that surface colonization provides. However, cheating types rapidly evolve that live in the biofilm but don't produce the polymer. The presence of cheats weakens the biofilm, imperiling its survival by causing it to sink.

In the new work, the researchers studied the effect of short-term evolution of diversity within the biofilm on the success of cooperation. The researchers found that within biofilms, diverse cooperators evolved to use different nutrient resources, thereby reducing the competition for resources within the biofilm. The researchers then manipulated diversity within experimental biofilms and found that diverse biofilms contained fewer cheats and can produce larger groups than non-diverse biofilms. The findings indicate that, as in ecological communities, biodiversity within biofilms is beneficial--moreover, the authors point out that this is the first time that such ideas have been applied in the context of social evolution, and it represents a new way in which cooperation can survive in the face of cheating. Furthermore, the new work sheds light on how division of labor within multicellular organisms may initially have evolved in order to minimize functional redundancy among cells and to increase efficiency.

Brockhurst et al.: "Character Displacement Promotes Cooperation in Bacterial Biofilms." Publishing in Current Biology 16, 2030–2034, October 24, 2006 DOI 10.1016/j.cub.2006.08.068. >from *Diversity promotes cooperation among microbes*. October 23, 2006

related context
> evolutionary path. the scale-free architecture that pervades biological networks gives them an evolutionary edge by allowing them to evolve to perform new functions more rapidly. august 25, 2006
> network structure impact on behavior. the interaction between social network structure and collective problem solving. august 10, 2006
> the spatial scale of competition. 'humans behave less cooperatively when they think they are in direct 'local' competition with each other, and more cooperatively under circumstances of 'global'-scale competition.' june 5, 2006
> cheats don't always prosper. 'cheaters produce energy rapidly by quickly taking in all the sugar they can and only partially converting it into energy. while this ensures swift energy production for the individual, it is a wasteful method that reduces resources available for the group as a whole.' may 26, 2006
> why we give. 'reciprocity is arguably the foundational basis of cooperation in humans. without some kind of payback, altruism can be a very costly endeavor in small-scale societies subsisting on wild foods.' december 30, 2005
> neural basis of altruistic punishment. september 10, 2004
> cooperation evolution. october 8, 2003
> coupled oscillators. -that is, entities capable of responding to each other's signals- will spontaneously self-organize april 9, 2003
> small-world networking. february 4, 2003
> social cooperation is rewarding to the human brain. 'during the mutually cooperative social interactions, activation was noted in those areas of the brain that are linked to reward processing.' july 19, 2002
> the new science of networks. june 6, 2002
> building a free flow of knowledge. march 15, 2002
> selected essays of richard m. stallman. 2002

imago
> coop nutrients

sonic flow
> cheats and broadens [stream]
cheats and broadens [download]

openfriday@straddle3
···························
cooperative spaces
hacklab + banco común de conocimientos + universidad pirata
friday, october, 27, 2006. 20 h
straddle3. c/ riereta, 32 1-3
barcelona