If the vocabulary doesn't exist(or isn't predominant), it becomes hard to point out the distinctions. Certainly, humans recognized from pre-civilized times that

If the vocabulary doesn't exist(or isn't predominant), it becomes hard to point out the distinctions. Certainly, humans recognized from pre-civilized times that there were children, but expectations of children were going to be different - in a smaller tribal society, for instance, each one would be a unique person. A more recent concept is the idea of the "teenager" in western culture - people who aren't adults and aren't children either.