Because I have the sort of annoying brain that simply will not stop, I often go to bed trying to puzzle things out. There’s a mounting body of evidence to suggest that not only does my brain continue this while I’m asleep, but also that it often comes up with answers too. The most notable example comes from when I was a child, staying at my grandparents house over Christmas, watching some war movie and realising that I didn’t understand how the ballast tanks in submarines work. Later that night, I apparently woke my little brother up in our shared room and explained how they worked to him, all without waking up. Clearly, my freaky brain had been figuring it out and, upon coming to a conclusion, decided to regurgitate the information immediately, whether I was awake or not.
What I didn’t realise is that my brain – if it doesn’t have anything to chew over – will go looking for things. This morning I woke myself up wondering aloud “Wait, why hasn’t Superman’s immune system wiped out all life on the planet? If living things from Krypton are invulnerable under our yellow sun, why haven’t we all been eaten by Superman’s intestinal bacteria?”
Hmmm, okay, this would have been solved if DC had kept to the origin from John Byrne’s Man of Steel mini-series, in which Kal-El is actually born on Earth from his gestation matrix and is never exposed to Krypton’s atmosphere. Recent interpretations of Superman imply that his powers developed slowly over time, and that he didn’t spend enough time to Krypton to be colonized by microbes, but that doesn’t address the problem of those older Kryptonians who come to Earth out of the Phantom Zone, or via delayed rockets (such as Kara Zor-El, AKA Supergirl).
You see, the situation gets even worse if you follow the classic Superman narrative, in which he is a baby on Krypton before coming to Earth. You see, this means that he’s had time to acquire a population of Kryptonian intestinal flora and fauna, as well as the various bacteria and viruses that exist on the skin of all living things. Under normal circumstances, this wouldn’t be a problem, but for one, tiny little fact.
Kryptonians – all Kryptonians – develop superpowers under our yellow sun. In the comics, Superman has had to deal with Kryptonian animals and once even a Kryptonian disease, and they all turned super on Earth. So Superman’s gut bacteria are super, which is fine as long as he never poops. Also, we shed living cells almost all the time as our skin replenishes itself. Under a yellow sun, those things are invulnerable. If they behave like normal cells do, they’d just keep replicating until they ran out of nutrients, but because they’re Kryptonian they could eat almost anything, survive almost anything.
Moreover, assuming that he is basically biologically human (as is implied by the fact that he can lose his powers under certain circumstances, which suggests that they are not an intrinsic result of his physiology but may actually be “extra-physical”), then he, as a human male, has probably experienced nocturnal emissions, as well as more deliberate ones – c’mon, he’s a guy. Are you honestly telling me you think he’s never had a wank? Sperm are normally very short-lived, but again, if they’re super-powered on Earth? That could get very, very messy (asee Larry Niven’s excellent satirical essay “Man of Steel, Woman of Kleenex” for a further exploration of this theme). He’s been made to bleed too. What happened to those blood cells? If his leukocytes and antibodies are indestructible, there’s no reason why they wouldn’t continue to function outside of him. If he’s a secreter, or if he ever bleeds, that stuff is out in the wild. Since everything not Kal-El will look like an infection to these cells, we’re looking at a biological apocalypse.
Forget the whole “fist fights levelling cities” thing. Kal-El is a walking ecological disaster waiting to happen. In Man of Steel (which I like), General Zod and his Kryptonian warriors could have wiped out humanity just by pooping out the hatch of their ship.