CAVEMAN RESPONSE TO INJURY?

About 10 years ago, I had a fairly substantial martial arts injury (3rd degree shoulder separation).  Something funny happened to me that day.  For the whole day, my appetite lit up, and I couldn't seem to eat enough.  I didn't think much of it later, but I had some minor surgery yesterday.  Same response.  The surgery wasn't anything particularly serious, but did result in a fair amount of residual pain (continuing as I write this, I might add).  My appetite took off again, and I felt almost insatiable in eating.  I don't have any scientific basis for this result, but I'm wondering if it may be part of some pre-programmed response from paleolithic times, designed to get enough nutrition in your body to help it heal.  I intend to research this, but for now, at least it's "food for thought", if you'll pardon the pun...........