Applying the cultural ratchet to a social artefact: The cumulative cultural evolution of a language game

Material artefacts evolve by cumulative cultural evolution (CCE), the accumulation of adaptive modifications over time. We present a large-scale experiment investigating the CCE of a social artefact in transmission chains, each containing 8 adult human participants (N = 408). The social artefact is what Wittgenstein calls a 'language game', the subset of language used to perform a particular activity; in the present study the language game is to communicate a route on a map. Two social learning conditions were compared: Observational Learning and Social Coordinative Learning. Participants tried to accurately communicate a route on a map to the next person in their transmission chain. Over the experimental generations the routes were reproduced with progressively higher accuracy in both conditions, demonstrating the CCE of the language game. The rate of CCE was comparable across conditions, but route reproduction accuracy was consistently higher in the Social Coordination condition compared to the Observation condition. In both conditions performance improved due to the accumulation of adaptive patterns of verbal route descriptions, and the progressive elimination of non-adaptive patterns. Whereas change in the content of the language game was similar across conditions, change to the communication process differed between the Observation and Social Coordination conditions. In conclusion, like material artefacts, social artefacts, in our case the language game, evolve by cumulative cultural evolution.