A new sign language has been created by deaf Nicaraguans over the past 25 years, providing an opportunity to observe the inception of universal hallmarks of language. We found that in their initial creation of the language, children analyzed complex events into basic elements and sequenced these elements into hierarchically structured expressions according to principles not observed in gestures accompanying speech in the surrounding language. Successive cohorts of learners extended this procedure, transforming Nicaraguan signing from its early gestural form into a linguistic system. We propose that this early segmentation and recombination reflect mechanisms with which children learn, and thereby perpetuate, language. Thus, children naturally possess learning abilities capable of giving language its fundamental structure.

Sound symbolism is a non-arbitrary relationship between speech sounds and meaning. We review evidence that, contrary to the traditional view in linguistics, sound symbolism is an important design feature of language, which affects online processing of language, and most importantly, language acquisition. We propose the sound symbolism bootstrapping hypothesis , claiming that (i) pre-verbal infants are sensitive to sound symbolism, due to a biologically endowed ability to map and integrate multi-modal input, (ii) sound symbolism helps infants gain referential insight for speech sounds, (iii) sound symbolism helps infants and toddlers associate speech sounds with their referents to establish a lexical representation and (iv) sound symbolism helps toddlers learn words by allowing them to focus on referents embedded in a complex scene, alleviating Quine's problem. We further explore the possibility that sound symbolism is deeply related to language evolution, drawing the parallel between historical development of language across generations and ontogenetic development within individuals. Finally, we suggest that sound symbolism bootstrapping is a part of a more general phenomenon of bootstrapping by means of iconic representations, drawing on similarities and close behavioural links between sound symbolism and speech-accompanying iconic gesture.

At what point in the process of speech production is gesture involved? According to the Lexical Retrieval Hypothesis, gesture is involved in generating the surface forms of utterances. Specifically, gesture facilitates access to items in the mental lexicon. According to the Information Packaging Hypothesis, gesture is involved in the conceptual planning of messages. Specifically, gesture helps speakers to ''package'' spatial information into verbalisable units. We tested these hypotheses in 5-year-old children, using two tasks that required comparable lexical access, but different information packaging. In the explanation task, children explained why two items did or did not have the same quantity (Piagetian conservation). In the description task, children described how two items looked different. Children provided comparable verbal responses across tasks; thus, lexical access was comparable. However, the demands for information packaging differed. Participants' gestures also differed across the tasks. In the explanation task, children produced more gestures that conveyed perceptual dimensions of the objects, and more gestures that conveyed information that differed from the accompanying speech. The results suggest that gesture is involved in the conceptual planning of speech.