The aim of this article is to mount a challenge to gesture-first hypotheses about the evolution of language by identifying constraints on the emergence of symbol use. Current debates focus on a range of pre-conditions for the emergence of language, including co-operation and related mentalising capacities, imitation and tool use, episodic memory, and vocal physiology, but little specifically on the ability to learn and understand symbols. It is argued here that such a focus raises new questions about the plausibility of (...) gesture-first hypotheses, and so about the evolution of language in general. After a brief review of the methodology used in the article, it is argued that existing uses of gesture in hominid communities may have prohibited the emergence of symbol use, rather than ‘bootstrapped’ symbolic capacities as is usually assumed, and that the vocal channel offers other advantages in both learning and using language. In this case, the vocal channel offers a more promising platform for the evolution of language than is often assumed. (shrink)

Iconic signs are overrepresented in the vocabularies of young deaf children, but it is unclear why. It is possible that iconic signs are easier for children to learn, but it is also possible that adults use iconic signs in child-directed signing in ways that make them more learnable, either by using them more often than less iconic signs or by lengthening them. We analyzed videos of naturalistic play sessions between parents and deaf children aged 9–60 months. To determine whether iconic (...) signs are overrepresented during child-directed signing, we compared the iconicity of actual parent productions to the iconicity of simulated vocabularies designed to estimate chance levels of iconicity. For almost all dyads, parent sign types and tokens were not more iconic than the simulated vocabularies, suggesting that parents do not select more iconic signs during child-directed signing. To determine whether iconic signs are more likely to be lengthened, we ran a linear regression predicting sign duration, and found an interaction between age and iconicity: while parents of younger children produced non-iconic and iconic signs with similar durations, parents of older children produced non-iconic signs with shorter durations than iconic signs. Thus, parents sign more quickly with older children than younger children, and iconic signs appear to resist that reduction in sign length. It is possible that iconic signs are perceptually available longer, and their availability is a candidate hypothesis as to why iconic signs are overrepresented in children’s vocabularies. (shrink)