Genetically suppressing one enzyme in mice makes them smarter, more open to new experiences, and less anxious. Of course, if you’re a mouse in the wild, cat urine should strike you with terror.
It has long been known that smarter people live longer. The usual speculation is either that their increment of intelligence helps them take better care of themselves, or that it brings an increment of wealth and social status that are also associated with longevity. A study of twins suggests the additional longevity is almost entirely genetic.