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Leaving undesirable partners
A sufficient condition to explain the evolutionary emergence of cooperation
Luis R. Izquierdo, Segismundo S. Izquierdo & Fernando Vega-Redondo
Abstract
How can cooperation arise and be sustained among individuals who may undermine
the collective good for their own benefit? It is clear that various species, from ants to
people, form social groups in which many individuals work for the common good. All
throughout evolutionary history, cooperation among individual units has been key for
Life to construct new levels of organization. Genomes, cells, multicellular organisms,
social insects, and human societies are all based on cooperation. However, natural
selection implies competition and therefore opposes cooperation unless a specific
mechanism is at work. So the question is clear: How can cooperation emerge and be
sustained in an evolutionary context?
In this seminar, we will study an extremely simple mechanism that is sufficient to
explain the evolutionary emergence of cooperation, i.e. conditional dissociation.
Conditional dissociation –i.e. the option to leave your current partner in response to
his behaviour– is a mechanism that dramatically affects the expected outcome of
social interactions.
In the context of social dilemmas, conditional dissociation has been shown to promote
the emergence and sustainability of cooperation. Nevertheless, this mechanism has
always been studied in situations where conditional dissociation was combined with
other factors that are also known to promote cooperation by themselves. In the
seminar, we will study the isolated effect of conditional dissociation in the evolution of
cooperation. To this end, we will analyse a formal model of a finite population of
individuals involved in a series of iterated Prisoner’s Dilemmas. Individuals in the
model can choose any strategy within a framework of predefined (minimal)
complexity, and are subject to evolutionary pressures. Using both computer simulation
(i.e. a computational agent-based model) and mathematical analysis (i.e. a meandynamics approximation), we will calculate the expected level of cooperation for a
wide range of parametric configurations.