Knut, the world’s most famous polar bear, is being threatened with the removal of his most precious assets. Rejected and left to die by his mother, separated from his beloved keeper, gawped at by hundreds of thousands of visitors as he struggled through teething and adolescence, Knut has had a raw deal in his short life. Berlin Zoo has made millions of euros out of merchandising the bear, who memorably posed with Leo di Caprio on the front cover of Vanity Fair, while Knut has had to make do with a daily bucket of herring. Now, to add injury to insult, German animal rights activists are demanding that he be castrated. It does not get much worse than that.