In a classic comic strip, most recently gracing the Beano, tiny characters called “numskulls” live in the head of a chap called Edd, controlling what he gets up to – often with hilarious results. It has run for decades, presumably because the idea that there could be critters within us capable of exerting a profound mental and physical influence seems pretty absurd.
But it appears science is having the last laugh: in recent years the idea has spawned myriad research papers – except that instead of minuscule people at work inside one’s head, it is microbes in the gut that appear to be pulling the strings.
