When researchers studied the brains of Romanian orphans - children who had been left to cry in their cots from birth and denied any chance of forming close bonds with an adult - they found a "virtual black hole" where the orbitofrontal cortex should have been. This is the part of the brain that enables us to manage our emotions, to relate sensitively to other people, to experience pleasure and to appreciate beauty. These children's earliest experiences had greatly diminished their capacity ever to be fully human. Sue Gerhardt's book Why Love Matters shows that early experience has effects on...