Humans produce numerous volatile compounds from different areas of the body, either as a direct result of metabolic processes or indirectly via metabolism of resident microflora. Body odours vary between individuals, partly due to genetic differences, but odours of the same individual also vary across time due to environmental influences.
We discuss how at least part of the genetic influence appears to be related to certain personality characteristics and to sexual orientation. We then review the current state of the art in terms of intra-individual variation, including effects of intrinsic factors such as hormonal influences on body odour and environmental factors, namely effects of diet and certain diseases.
Some of these changes can be perceived by other individuals and might therefore provide social cues of current motivational, nutritional and health status. Finally, we discuss how specific odour profiles associated with certain infectious diseases and metabolic disorders can be used as a cheap and efficient medical screening tool.