Autor: Skinner B.F.
Evolutionary theory has always been plagued by scantiness of evidence. We see the products of evolution but not much of the process. Most of the story happened long ago, and little remains of the early stages. Especially few traces of behavior remain; only recently were there artefacts that could endure. Verbal behavior left no artifacts until the appearence of writing, and that was a very late stage. We shall probably never know precisely what happened, but we ougth to be able to say what might have happended – that is what kind of variations and what kind of contingencies of selection could have brought verbal behavior into existence. Speculation about natural selection is supported by current research on genetics; the evolution of a social enviroment or culture is supported by the experimental analysis of behavior.