He specializes on the origin and evolution of cooperation, and conflicts between the levels of selection. The levels he addresses range from interspecific cooperation between fungus-growing termites and their symbiotic fungi to cooperation between genomes within cells. After finishing his PhD on speciation of fungi at Wageningen University in 1999, he became a postdoc and later assistant professor at the University of Copenhagen and returned to Wageningen in 2006. Duur Aanen uses fungi as his main experimental model system. Fungal ‘individuals’ can fuse and form chimeras, can be used in evolution experiments and are important mutualistic partners of other species, characteristics that make them excellent model systems for the evolution of conflict and cooperation.