Cumulative cultural evolution in the laboratory: An experimental approach to the origins of structure in human language

doi:10.1073/pnas.0707835105

Cumulative cultural evolution in the laboratory: An experimental approach to the origins of structure in human language

*School of Philosophy, Psychology, and Language Sciences, University of Edinburgh, Edinburgh EH8 9LL, United Kingdom; and
^‡Division of Psychology, Northumbria University, Newcastle-upon-Tyne NE1 8ST, United Kingdom

Edited by Dale Purves, Duke University Medical Center, Durham, NC, and approved June 6, 2008 (received for review August 20, 2007)

Abstract

We introduce an experimental paradigm for studying the cumulative cultural evolution of language. In doing so we provide the first experimental validation for the idea that cultural transmission can lead to the appearance of design without a designer. Our experiments involve the iterated learning of artificial languages by human participants. We show that languages transmitted culturally evolve in such a way as to maximize their own transmissibility: over time, the languages in our experiments become easier to learn and increasingly structured. Furthermore, this structure emerges purely as a consequence of the transmission of language over generations, without any intentional design on the part of individual language learners. Previous computational and mathematical models suggest that iterated learning provides an explanation for the structure of human language and link particular aspects of linguistic structure with particular constraints acting on language during its transmission. The experimental work presented here shows that the predictions of these models, and models of cultural evolution more generally, can be tested in the laboratory.

Footnotes

^†To whom correspondence should be addressed. E-mail: simon{at}ling.ed.ac.uk
Author contributions: S.K., H.C., and K.S. designed research; H.C. performed research; S.K., H.C., and K.S. analyzed data; and S.K. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
↵ § From a practical perspective it is also an ideal subject for study in that it is relatively straightforward to record and analyze precisely.
This article contains supporting information online at www.pnas.org/cgi/content/full/0707835105/DCSupplemental.
↵ ¶ Arguably, the dance of honey bees (35) and the calls of Campbell's monkeys (36) are both minimally compositional. However, there is no evidence (as yet) for culturally transmitted or open-ended compositional communication outside our species.