At a moment when the world feels like a particularly unsettling place, Guardian podcast Science Weekly is asking what it is that makes humans happy – and how can we bring more happiness into our lives? In episode one of this two-part series, Ian Sample asks what makes a country happy. Johannes Eichstaedt, assistant professor of psychology and human-centred AI at Stanford University, explains why the Nordic countries often rank highly in the annual World Happiness Report and what we can learn if we look beyond them