In the last decade, basic neuroscience research has shown a heavy and growing bias (>75% of the total research effort) towards studying rats, mice, and humans. These three species represent about 0.0001% of the total diversity of nervous systems, yet neuroscientists routinely extrapolate findings from laboratory rodents to humans, or even to all species. Historically, neuroscience research has studied a wide diversity of animal species, choosing model systems that best suit a particular, well-defined scientific question. Squid, chickens, frogs, pigeons, canaries, dogs, cats, flatworms, crabs, fish, and monkeys, to name just a few, have made crucial contributions to our understanding of the basic functions and structures of nervous systems. So why has current neuroscience research converged on a handful of standard model organisms? What can we gain from a diversity of model organisms and a comparative approach to both basic and translational research? And if the time has come for a methodological revolution, what will it take?