David Sumpter is professor of applied mathematics at the University of Uppsala, Sweden, where he runs the Collective Behaviour Research Group. An incomplete list of the applied maths research projects on which David has worked include pigeons flying in pairs over Oxford; clapping undergraduate students in the north of England; the traffic of Cuban leaf-cutter ants; fish swimming between coral in the Great Barrier Reef; swarms of locusts traveling across the Sahara; disease-spread in Ugandan villages; the gaze of London commuters; dancing honey bees from Sydney; and the tubular structures built by Japanese slime moulds. His books include Soccermatics and Outnumbered.