What are the views on language development ? 

There are several views on language development:
(1)that hominid language involved gestures or hand movements;
(2)that spoken language was preceded by vocal but non-verbal communication such as singing or humming;
(3)that human speech probably began with calls like the ones that have been observed among primates.
(4)Humans may have possessed a small number of speech sounds in the initial stage. Gradually, these may have developed into language.