Traditionally our sense of smell has been downplayed as relatively unimportant, especially in the modern age. Research shows, however, that the human body's biggest gene family, making up around 1percent of our DNA, is dedicated to olfactory processes. We can in theory distinguish between over a trillion different odours. Why the complexity, and to what purpose?. Researchers call smelling our most primeval sense. The part of the brain where odours are decoded is directly connected to the limbic system the source of memories and emotions. Our immediate reaction to a smell is as such a feeling. All humans have an individual sense of smell; there are no two identical 'noses'. What we all share, however, is a feeling of revulsion to unpleasant smells a sensation unique to homo sapiens. It turns out that the triggers are not pre-programmed in our DNA. Every society has its own cultural norms that define our perception of smells but there are also certain odours that result in identical signals being sent. Somewhat surprisingly, our olfactory receptors are located not only in the nose but all over the body: in the liver, the kidneys, and with men in the testicles. Where do our preferences and aversions for smells come from? And in which other parts of the body do odour molecules play an important role? This documentary presents the latest insights into our sense of smell.