Using the standard van der Pol–FitzHugh–Nagumo excitable medium model, I demonstrate a generic mechanism, diversity, that provokes the emergence of global oscillations from individually quiescent elements in heterogeneous excitable media. This mechanism may be operating in the mammalian pancreas, where excitable $\beta$ cells, quiescent when isolated, are found to oscillate when coupled, despite the absence of a pacemaker region.

• Received 31 March 1999

DOI:https://doi.org/10.1103/PhysRevE.62.1149