Abstract
The evolution of cooperation has been a focus of interest for evolutionary biologists for over a hundred years (Darwin 1859; Kropotkin 1908; Williams 1966). While all forms of cooperation challenge the centrality of competition in the process of evolution, cooperative and eusocial breeding systems, where offspring produced by a small number of breeding individuals are reared by nonbreeding helpers or workers, raise some of the most fundamental questions about the level at which selection operates the measurement of....