The passage makes the point that we now have ____

A subject in which there has been a lot of interest
recently is the acquisition of language. ‘Normal'
children - that is, those who have not had a
particularly rich early environment - usually begin
talking after the first year of their life. By eighteen
months they have a vocabulary of about half a dozen
words; at two years a vocabulary of more than a
hundred words. The traditional view has been that
during the first year of life babies are not mature
enough to learn languages. Talking, however, is only
the outer manifestation of the development of the
language. Long before he first utters a meaningful
word a baby can be observed responding to the
language of the others.