Main description: Why do humans, uniquely among animals, cooperate in large numbers to advance projects for the common good? Contrary to the conventional wisdom in biology and economics, this generous and civic-minded behavior is widespread and cannot be explained simply by far-sighted...

We study the simple evolutionary process in which we repeatedly find the least fit agent in a population of agents and give it a new fitness which is chosen independently at random from a specified distribution. We show that many of the average properties of this process can be calculated...

A simple model of tag-mediated partner selection for agents playing the IPD is described. The agents strategies are represented as (i,q,q) triples as in [Nowak and May, 1992]. The tags are represented as arbitrary real numbers in [0,1], and tag selection is biased toward agents with similar...

A model of an evolving network of interacting molecular species is shown to exhibit repeated rounds of crashes in which several species get rapidly depopulated, followed by recoveries. The network inevitably self-organizes into an autocatalytic structure, which consists of an irreducible 'core'...

We introduce a method for visualizing evolutionary activity of genotypes. Following a proposal of Bedau and Packard[11], we define a genotype's evolutionary activity in terms of the history of its concentration in the evolving population. To visualize this evolutionary activity we graph the...

Evidence for somatic hypermutation of immunoglobulin genes has been observed in all the species in which immunoglobulins have been found. Previous studies have suggested that codon usage in Ig V genes is such that the sequence-specificity of somatic hypermutation results in greater mutability in...

The causes of major and rapid transitions observed in biological macroevolution as well as in the evolution of social systems are a subject of much debate. Here we identify the proximate causes of crashes and recoveries that arise dynamically in a model system in which populations of (molecular)...

"Nothing in biology makes sense except in the light of evolution." It would be hard to find a biologist today who disagrees with geneticist Theodosius Dobzhansky's famous claim. Darwin's theory of evolution via natural selection has done more than any other principle to explain the biological...