I wouldn't see any evolutionary advantage of being a Zoophile. The whole point of copulation is to pass along your genetic information to your offspring. The only reason it's pleasurable, is to entice us mammals to engage in the activity, by releasing endorphins and dopamine. So that we want to copulate in the first place. While having sex with animals will release these very same chemicals in you and your animal partner's brain. The very fact that we cannot make babies with them doesn't make any evolutionary sense. If you're zoo-exclusive, you've pretty much ended your own bloodline, though not necessarily your family's bloodline if you have siblings.
But humans have long broken the natural cycle of evolution. The very fact that the weak, stupid, and disabled and freely produce children and not have nature bump them off proves it. Which I know sounds very harsh, but nature doesn't play nice. The very fact that we have means of birth control, to take advantage of the joys from having sex without producing offspring proves we've broken evolution. Man-made society isn't natural.