They don't know why. What they do know, from Gallup's survey of 340,000 people throughout the U.S., is that we get happier as we age. That's what THE NEW YORK TIMES reports.
The head of the study Arthur Stone speculates, "It could be that there are environmental changes ... or it could be psychological changes about the way we view the world, or it could even be biological - for example brain chemistry or endocrine change."
My take? It's that we have somehow survived. That experience gives us confidence that we can handle anything. The chronic angst is gone.