Our long, vulnerable childhoods may be the key to our success

The central question in Brenna Hassett’s book, put simply, is: why are our children so very useless for so very long? Or: ‘What is the possible adaptive value of teenagers?’ If we consider maturity, or adulthood, to be the point at which an animal can play its own role in the evolutionary process – i.e. have its own babies – why is it that we have evolved to mature so slowly; and, even when mature, to delay having children until many years after we’re first physically capable of doing so? The framework in which Hassett sets out to answer this is one to do with investment and return on investment.