Evolutionary continuity and the rate and curve of language evolution

One of the most prominent questions in connection with language evolution is whether the human capacity for language can be related to any capacities found in animals. Evolutionary continuity in anatomical structures involved in language is obvious, but in the case of cognitive capacities and behavior it is rather controversial. A correlation has often been implied between quantitative difference and evolutionary continuity on the one hand and qualitative difference and evolutionary discontinuity on the other. Recently these two positions have even incorporated claims of gradualistic and punctuated evolution of language respectively. These suggested correlations can hardly be true because the question of the rate and curve of language evolution is only indirectly connected to the continuity-discontinuity debate. It is highly unlikely that there could be true discontinuity in language evolution due to the lack of any antecedent trait. Rather, seeming missing links can also occur in the case of continuous traits when there is enhanced selection pressure due to rapid or even sudden environmental changes and hence rapid evolutionary change takes place. This is more logical even from an adaptationist point of view than a constant rate evolution. Thus, while elements of the primate communication system, cognitive capacity and social behavior must have served as evolutionary forerunners of language in the form of preadaptations, the rate and curve of language evolution must have depended on the selection pressures driving it.