In many scientific disciplines, scientists generally do not do highly creative work beyond the age of forty, a tendency that has normally been taken to show that aging carries with it a loss of creative capacity. However, by the age of forty most scientists have been working in their chosen field for at least fifteen years
an alternative explanation is that spending too long in a single field reduces the opportunity for creative thought.
Whether scientists' choice of research projects tends to be influenced by their own belief that their most creative work will be done relatively early in their career