The software that analyses images of your face, captured online or when you're out and about, has rapidly improved. Adam visits Amscreen, to test the cameras they deploy at supermarket checkouts to determine your age and sex, to inform advertisers of the best demographic to target. This raises ethical and privacy issues which Adam discusses with privacy expert Professor Colin Bennett and author of "The formula, about algorithms and the algorithm culture", Luke Dormehl.

Quantifying expressions

Is a look of contempt, or a smile, a universal expression or do they vary across cultures? Marnie Chesterton visits Glasgow University's Institute of Neuroscience and Psychology, where the scientists are building a huge database of faces, in order to unpick and quantify our expressions. Dr Oliver Garrod from the Generative Face Grammar Group demonstrates how they can capture your face, and animate it.

Evolutionary psychology

There is a long list of evolutionary explanations for the human condition. Mostly these are quite trivial. Teen boys develop acne on their faces to deter females from fertile but psychologically immature mates. Babies cry at night to prevent parents further procreating, resulting in potential sibling rivals. At the other end of the scale, these sorts of explanations have been used to suggest deeply problematic ideas, such as rape being an evolutionary strategy.

Professor David Canter, a psychologist from University of Huddersfield has railed against this fashion for 'biologising' our behaviour. And evolutionary biologist Professor Alice Roberts is also critical of 'adaptionism' - the idea that everything has evolved for an optimal purpose.

Producer: Fiona Roberts.