One of the four episodes in the BBC’s Human Instinct series, this documentary takes us on a voyage of discovery of some facets of human behaviour. In this episode the histrionic host reveals the biological mechanisms behind the different sexual instincts of women and men. It starts off with two attractive young people – a woman and a man – making passes on flabbergasted passers-by under the watchful eye of hidden cameras. Needless to say, the men reacted quite differently from the women: the universal disinclination of the women to casual sex is explained as the evolutionary instinct to choose the best father for their offspring, given the undeniable burden of pregnancy. This documentary presents curious experiments (sweaty T-shirts and personal transformations bordering on the incredible!) as well as disconcerting tales of jealousy and infidelity that attest to the biological diversity behind the different sexual behaviours of men and women.