Funny point you made. I was watching that once, and true to your point, they were running up a tree, down a tree, across the ground here and there, with 2 never catching 1. Then a Hawk appeared (swooped at one of them) and they both kicked it up a notch.
I will never forget an old timer I knew... just had patches of hair here and there, more gum then teeth, always with a "motivator" in his flask. He used to tell me (this is when I was 16 or so) that when the chaser catches the runner, the chaser bites off the runners "boys" (i.e. castration by dentition). He would go on and on about it, and used to tell us that during the mating season they would try to run up your pant legs and castrate you if your balls had already dropped.... then he would would take a long pull off the flask, and look at us and say... I sure hope yours haven't dropped yet!