A theoretical article co-authored by Robin, this paper presents a new idea called the 'social complexity hypothesis'. Basically, the paper outlines a hypothesis about how 'social complexity' might lead to 'communicative complexity' in a wide variety of species and/or social systems, based on 5 key principles, including: unit size, unit density, member roles, egalitarian structure, and home-range size (i.e. inter-unit density). Social complexity is further discussed as a driver of communicative complexity and a possible causal factor in the origin and evolution of human language.
Here is the link: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3367695/pdf/rstb20110213.pdf
Here is an interesting link also to a video podcast interview Robin did in connection with the article, explaining in broader terms the idea(s) behind the paper: http://rstb.royalsocietypublishing.org/content/suppl/2012/07/03/rstb.2011.0294.DC1