I remember reading a study that showed that regardless of language, (2 of the many they looked at were English and Swahili) mothers tended to speak to their beginning-to-talk infants at a developemental level 1 stage ahead of the child's ability. If the child spoke in one word sentences eg "mine" then the mothers tend to respond with 2 word sentances eg "baby's ball". So not only the need to communicate and the ability to symbolize are innate but the ability to adjust communication is also innate.