The law says you're legally an adult at age 18, but new scientific research finds people don't really hit adulthood until they're in their thirties. University of Cambridge researchers examined the brain, and neuroscientist Peter Jones says, "What we're really saying is that to have a definition of when you move from childhood to adulthood looks increasingly absurd. It's a much more nuanced transition that take places over three decades." Looking at it another way, the brain is going through major changes when a person is an adolescent-- accounting for much of adolescent behavior, but the changes don't end as someone leaves their teens. Jones adds, "There isn't a childhood and then an adulthood. People are on a pathway, they're on a trajectory."