Doesn't seem too far fetched to me. I've seen all sorts of interesting characteristics on creatures, just look at that butterfly with the face of an owl for wings. Whether or not the japanese are correct about the reincarnation of samurai, selectively killing only those without the "faces" is going to cause a boost in that population. Also, if you really want to observe evolution just look at dogs. My border-collie is the result of thousands of years of selective breeding, as are many of the extreme varriations in dogs, all of which come from only 4 or 5 innitial canine species.