I used to think that typos and grammatical errors were my fault. Diligently, I would go through a story, correcting and re-wording, until everything read perfectly.
Then I'd come back to the story some time later and find more typos and more laboured English. I used to think I simply missed them on previous read-throughs, but now I have realised that is not the answer.
The truth is that typos breed. They may well reproduce asexually, like a nematode worm or even do it via spores - put your checked manuscript next to a book with a bit of dodgy typography and next time you pick it up there'll be an apostrophe against a possessive it, an 'a' instead of an 'an' and even a 'their' when you're sure you wrote 'heterogenous'. Whatever the mechanism, they undoubtedly do it.
Given this breakthrough in re-writing research, has anyone any suggestions for how to quell writing mistakes' reproductive instincts? Can they be neutered? Would writing at minus 100 degrees celsius do the trick? How about sealing up your word processor inside a bioprotective bubble?