A crucial issue posed for the understanding of human cognition, and indeed human evolution more generally, is how what Peirce called symbols emerged in the natural world. Unlike the iconic and indexical forms of semiosis that sustain the organization of life throughout the biological world, symbols are not inherently meaningful, but instead are lodged within communities of interacting actors who recognize them through rule, habit, or convention. No other animal pervasively uses symbols to organize action and shape understanding. The action-relevant importance of symbols is demonstrated by the attempts of an aphasic man to organize the subsequent actions of others with iconic and indexical signs alone. Movement to a next action is systematically delayed by the task of establishing what, of many possibilities, these signs mean now. This does not occur with symbols. Co-operative action thus provides an environment that would both promote and sustain the emergence of symbols by making powerful new forms of rapid, flexible action possible. Indeed, symbols, which sit at the center of human language, are themselves forms of co-operative action. Co-operative action is contrasted with modal, gesture-first theories for the origins of language.

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