Why do we have margins? Rats! well, partly. People really did leave empty space around the edges because rats kept nibbling off important information. But although rodents accidentally helped inspire the habit, the margins we use today also developed for a smudge free, practical life. So yes, rats chewed on pages. But the bright red margin line? That came later, thanks to typewriters and neatness rules. Still, if you forget an assignment, don’t blame the dog. Just say the rats ate your homework!

This tiny magnetic blob could change how we treat brain tumors forever...