Why humans take so long to grow up

Why do our children take so long to grow up, compared to other animals? We all know that humans have big brains. In common with apes, we grow relatively slowly and generally have long lives. What is not yet entirely clear is why we have this slow steady development and live longer than species with smaller brains. One theory is that species with big brains are more intelligent and flexible in their behaviour and therefore survive better for longer. However, our anthropologists may have found a different answer, which flips on its head the idea that certain areas of the brain are fairly 'primitive'. They suggest that a large and complex brain simply takes longer to grow and 'wire up' meaning that large-brained species mature later. Different brain regions, however, have different schedules.