The man who steps up to take questions from the press at the launch of the Hayward Gallery’s new exhibition looks like a science geek dressed up as an artist – which, on closer inspection, is what he is. Carsten Höller, creator of the gallery’s summer exhibition “Decision” (until 6 September), started his working life in the 1980s as an agricultural entomologist, earning his doctorate for an “Efficiency Analysis of the Parasitoids of Cereal Aphids”. A relic of his past hangs on the stairwell in the shape of a giant aphid in the act of self-reproduction. As might be expected of this master of the unexpected, his greenfly is pink. “I always wondered, ‘What would you think about an aphid that was as big as a dog?” is his only e