The idea of four primary tastes has influenced our concept of the gustatory world of all animals. It has also been the basis for constructing theories of gustatory neural integration. Since natural chemical stimuli are complex mixtures to which responses are multineuronal, difficult questions about integration arise. Answers are usually framed in terms of "labeled line" or "across-fiber" hypotheses. Comparative studies of vertebrate and invertebrate taste reveal in all receptors universal basic parameters that bear on the controversy. Comparative studies also place in more accurate perspective diverse chemically related ecologies and behaviors.