[Thatcherite]

Gazelles are slower that cheaters because they don't have to be faster than cheetahs, they only have to be faster than at least one other gazelle in their herd. The slowest gazelle (or least alert) in a stalked herd gets eaten, but this may often be an old gazelle, that has already successfully bred descendants when it was younger and quicker. Over time the selection resulting from the speed race between cheetahs and gazelles may cause them to evolve, or it may not if their environment doesn't change and they are already highly adapted for it.

[Thatcherite]

Oh My ... , did I really type "cheaters". It wasn't me, honest, it was just those fingers of mine.