The Study of animal communication has a long and colorful history. In the 1950s Dutch biologist Niko Tinbergen collected stickleback fish and carefully observed how they interacted. He noticed that the abdomen of male fish would flush bright red during breeding season, as the fish built nests and established their territories. This color served as a warning signal to rivals—so much so that Tinbergen found that territorial males would lunge at any object with a similar hue, including wood blocks he held outside their tank and even a mail van passing by the laboratory window.
Tinbergen's work—which combined the observation of natural behaviors with systematic experimentation—not only earned him a Nobel Prize, but it became a model for the study of animal communication. This classic approach has proved so successful in understanding how animals interact, it seemed only natural to use it for investigating human discourse. Our goal was to discover what people—from a variety of cultures, in the act of everyday conversation—could tell us about the structure of human language.