Food flavours are the combined response of our chemical senses of taste and smell (odour) – with the sense of smell more sensitive than the sense of taste and the greater contributor to our perception of flavour.
Our sense of smell (olfaction) comes from special nasal sensory cells which interpret certain molecules in the nasal cavity as having a particular smell, the sensory signals passing to the olfactory bulb below the frontal brain lobe). Like the sense of taste, smell is detecting chemicals with chemoreceptors, the chemicals being mostly volatile small molecules, non-volatile proteins, and non-volatile hydrocarbons.
The olfactory gene family makes up about 1% of all the genes and is the largest in the mammalian. Each species has an olfactory repertoire unique to the genetic makeup and humans can detect millions of airborne odorants and there is great genetic variation in olfactory genes reflecting cross-cultural differences. There are a small number of human pheromones (sex attractants) and the consumer product industry of perfumes, food and drinks invests billions of dollars in research. Anthropology still has much to learn about our sense of smell in relation to behavioral and social cues, evolutionary history, mate choice, food decisions, and overall health.
Little has been suggested concerning the functions of the human olfactory system with research centred on olfactory malfunction (onosmia), olfactory senses of mammals, and analysis of evidence for particular theories. Functions may frequently be associated with other senses especially taste but have been placed in three broad areas: ingestive behaviour (detection of undesirables, energy-rich or other desirable or undesirable foods, appetite regulation),, environmental hazard avoidance (association especially with with fear and disgust), and social communication (sexual signals, fitness detection, immune-chemical signals and biological compatibility, maternal odours, emotional contagion, fear an stress). There is also the possible evolutionary historical purpose of navigation.
Association of smell with particular kinds of plants or their parts is best known through its links to taste. Though the sweet-smell of flowers like roses and jasmine is assumed to be attracting insects when the flowers are ready for pollination, its function in humans is not known, if indeed there is one: it is unlikely that humans ever acted as pollinators.