I didn't enjoy listening to this one very much, but I sure enjoyed thinking about it afterwards.
It was apparent quite quickly to me that the narrator was going to triumph, and I didn't feel any real sense of drama in the buildup to the showdown. I also wasn't expecting (or liking) the cause of the hum to be . . . aliens camped out in a supermarket. I was expecting a natural phenomenon, or a science experiment gone wrong. Or even some kind of industrial accident – perhaps someone trying to jury-rig a power plant in a way that generated a maddening hum. I got plenty hung up on why would aliens who have mastered intersteller travel would behave so strangely and ineffectively. The showdown was far too “Independence Day” for my taste in its unlikelihood as well.
All that said, I do like how this story reinforces what is, to me, one of the key pieces of proof of the method and power of evolution. Namely, the fact that evolution consists of two parts – random variation and culling of those without certain traits. The simple fact that humanity is so diverse right now is a kind of proof (to me) that evolution has already happened. We are different in ways that could make a difference between life and death in many different situations. We are probably a single global disaster away from demonstrating (to those who find the concept of evolution scary to their belief system) that the evolving of the human race has already happened. If a new black death plague kills 95% of all humans, except those who randomly produce a single enzyme, or if a nuclear winter raises radiation to a level that kills 98% of all humans, except those with a unique metabolism, it is likely that nearly all humans afterwards will share whatever trait saved them. We do not need to wait for the global disaster to actually understand this point.
What I liked about this story is that it may be improbable that having OCD will be the difference between surviving an apocalypse, it is not impossible. And we have no way of knowing right now which random trait may be what saves a subset of our children's children from some catastrophe they never see coming.