Caregiver communication to the child as moderator and mediator of genes for language Luca Onnis a a Division of Linguistics and Multilingual Studies Nanyang Technological University, Singapore. Abstract Human language appears to be unique among natural communication systems, and such uniqueness impinges on both nature and nurture. Human babies are endowed with cognitive abilities that predispose them to learn language, and this process cannot operate in an impoverished environment. To be effectively complete the acquisition of human language in human children requires highly socialised forms of learning, scaffolded over years of prolonged and intense caretaker-child interactions. How genes and environment operate in shaping language is unknown. These two components have traditionally been considered as independent, and often pitted against each other in terms of the nature versus nurture debate. This perspective article considers how innate abilities and experience might instead work together. In particular, it envisages potential scenarios for research, in which early caregiver verbal and non-verbal attachment practices may mediate or moderate the expression of human genetic systems for language. Keywords: attachment; child-directed speech; epigenetics; Gene x Environment interaction; caregiver-child interaction; language development. 1. Introduction Many living species have evolved elaborate communication systems over millions of years [1], yet human language is recognised as a form of communication unique to homo sapiens. Because of this unique species trait, several researchers have postulated that the human language faculty must somehow depend on a species-specific genetic component. Yet the specific genetic bases of language are still largely unknown, and are now being explored with the advent of genetic methods. The evidence so far has mainly highlighted possible genetic bases for developmental language disorders, and in a few instances certain genes have been linked to earlier or faster language development in normally developing children. Because language is a complex trait, it is likely that many genetic systems support its development, whether in typical or atypical populations [2]. Likewise, genes that participate in the language phenotype are likely to regulate several other non-linguistic abilities and functions [3]. Human language is also unique as a system of communication in the animal kingdom in that it is a learned activity requiring massive exposure and intense socialisation with multiple tutors. It takes children at least their first 5 years of life to be able to communicate fluently. For robust language abilities to emerge, sustained socialisation and interaction between the child and primary caregivers are fundamental. Thus, besides basic innate capabilities, the language environment appears critical to the life-course trajectory of a child. Researchers emphasising the contribution of the social environment to language have discovered that quantity, content, and quality of language input all dramatically affect child language development [4]. Large differences in linguistic skills emerge very early during infancy and childhood, and persist throughout Preprint submitted to Elsevier February 1, 2017