Hall and other geneticists have more fundamental insights in mind. Bio-clocks could have been invented and reinvented several times during the long history of evolution, Hall says. But just as we are built for Earth gravity and Earth temperature and pressure, we are also genetically coded for the 24-hour cycle that defines life at this location in this solar system. The chances of easily finding an identical setup on distant galactic shores are slim. And unless we can reengineer our clocks, we are going to have a hard time keeping up with the locals.
Insects have that capability.
The window is much narrower for mammals. Circadian mutants would still be human. They just wouldn't be earthlings any longer.