I thought I had read that observations of MIR cosmonauts had revealed that the 24 hour body clock is largely a myth, at least among humans, and that the men and women on board will, once removed from the earth's 24 hour cycles, adapt to seemingly random and subjective cycles of waking, feeling hungry, bodily functions, sleeping, etc. regardless of what the clock tells them they should be doing at the time...

And if my math is correct, the dinosaurs should have had a 22 or 23 hour body clock when they lived, given the slowing of the earth's rotation.

"Man is the only animal who glances at his wrist to see if he is hungry"

- who said that?