In Don Siegel’s 1956 film shocker Invasion of the Bodysnatchers a California doctor becomes convinced that his patients are being taken over by alien replicants. They look the same; they’re just strangely emotionally absent. As those around him morph into their affectless lookalikes, it’s the frantic doctor who seems insane. “Relax, don’t fight it,” he’s advised – can’t he see that it’s easier, simpler – better – to live in a world without unruly emotions – all the messy downsides of humanity?