I was surprised to read this in Wikipedia: http://en.wikipedia.org/wiki/Child#As_a_non-adult - "Recognition of childhood as a state different from adulthood began to emerge in the 16th and 17th centuries. Society began to relate to the child not as a miniature adult but as a person of a lower level of maturity needing adult protection, love and nurturing. This change can be traced in painting: In the Middle Ages, chi…
I don't think that point of view even makes sense. Humans and lower mammals are all born more or less helpless. They require caring parents for nourishment and protection in order to survive. Certainly you can argue that the period of "childhood" has been greatly extended in recent centuries, but it makes no sense that the concept of a child as something other than just a physically smaller adult emerged in the 16th…
A more recent concept is the idea of the "teenager" in western culture - people who aren't adults and aren't children either.