Beyond buttocks: this Turner prize shortlist is cheeky and smart

There’s no singing, no painting and not a video in sight. But we do have choo-choos, a live ant farm – and plenty of puzzles and gamesThis is a good and in some ways unexpected Turner prize shortlist. I have been expecting Helen Marten to appear for a couple of years – unless, as artists sometimes have, she declined to show until now. Last year was Assemble’s moment, and their inclusion heightened a debate about collective and socially engaged art that was worth having.Re