Interesting story :
Academics who leave academia for industry and then return are more productive.
This is fairly intuitive. Outside academic the researcher got a broader education, learned some other new skills and ideas, met new people, all of which could then be cross-pollinated back into academic research. (Compare OnCreativity)
But now, the coming back is the bit that intrigues me at the moment. What reminds me of is ElaineMorgan's AquaticApeTheory. She suggests that during the pleistocene era (12 million year droubt in Africa, when forrests were disappearing) human-ancestors left the land to spend time back on the coast, and a great deal of time in the water. (Not living under-it, simply along the shore, hunting sea-animals, and spending most of the day wading in the surf-zone.)
It's a good theory of why humans have various characteristics different from other higher apes (no fur except on head, walking upright, emphasis on sound rather than scent for signalling, large breasts, salt-tears etc.) And the interesting thing for this page, is that the process of adaption is not reversable.
When humans left the sea, they didn't simply undo the changes, grow more fur, return to using scent etc. Partial adaptions turn into the basis for the new trajectories of evolution. But there's some interesting benefit through being put through a variety of environments selecting for different things. At one point Morgan offers elephants as an interesting analogous case of an animal which spent time becoming partially aquatic and then returned to the land with several new capabilities : eg. able to swim (something quite extra-ordinary if you compare most large four-legged mammals.)
It also reminds me, of course, of HowBuildingsLearn which points out that some of the most interesting / aesthetically pleasing buildings are those who's functions change over time : churches which become workshops, houses which become shops, boats which become homes etc. Each partial adaption adds a new layer of history and physical changes, which are often visible and present new design challanges and opportunities to each successive phase of adaption.