Category Acquisition and the Origin of Language
Stevan Harnad
Indiana University
5 December 2005

About 100,000 years ago there occurred an explosive evolutionary change in our genomes, brains and behavior: the advent of language. This change had to be driven by something that conferred an enormous adaptive advantage on our species, the only one with language. I will argue that the advantage was a new and unique way of acquiring categories: by explicit boolean descriptions of categories instead of just implicit trial and error learning. Categories are very general: To categorize is to do the right kind of thing with the right kind of thing. In other words, it is just about all of adaptive behavior, learned and inborn. I will discuss some computer simulations of language origins, some experiments on the implicit and explicit learning of perceptual categories and grammatical rules, and some properties of lexical representation and symbol grounding revealed by the analysis of the definitional structure of digital dictionaries.

Cangelosi, A., Greco, A. & Harnad, S. (2002) Symbol Grounding and the Symbolic Theft Hypothesis. In: Cangelosi, A. & Parisi, D. (Eds.) Simulating the Evolution of Language. London, Springer.