At the end of "Survival of the Unfit," you won't walk out of Arkansas Public Theatre laughing and singing. This isn't "Little Shop of Horrors." But there is something inhuman -- vile, grotesque, maybe even monstrous -- growing in the little suburban household of playwright Oren Safdie's imagination. It deserves to be seen, explored -- and perhaps a lesson learned that might keep it from proliferating in other households elsewhere.