Homo economicus
In his dissertation, published in 1993 in Berlin, Elworthy created the model of "Homo biologicus" which explains human behaviour in terms of evolutionary theory and phylogenetic and ontogenetic development. "Homo biologicus" is linked to, but extends, the economic Homo economicus model, which describes man as a rational and self-interested being. The core hypothesis is derived from evolutionary psychology, and proposes that human psychological processes were shaped by natural and sexual selection to solve evolutionarily relevant problems. Some of these relate to somatic effort, and are economic in nature, while others relate to reproductive and social behaviour which are inexplicable within a conventional Homo economicus paradigm. Elworthy's theory stands in the tradition of authors like E. O. Wilson or Richard Dawkins, who are controversial among social scientists and frequently criticized for their alleged biologism. In later academic work Elworthy examines on the interactions between social institutions and human psychology and the behaviour that results. His habilitation analyses constitutional developments in New Zealand, and their enabling role in the dramatic liberalisation from 1984 to 1993.