Research shows that men find it particularly difficult to interpret the more subtle cues in women's body-language, and tend to mistake friendliness for sexual interest.
Another problem is that in some rather Puritanical cultures, such as Britain and North America, flirting has acquired a bad name.
They argue that the large human brain – our superior intelligence, complex language, everything that distinguishes us from animals – is the equivalent of the peacock's tail: a courtship device evolved to attract and retain sexual partners.
Our achievements in everything from art to rocket science may be merely a side-effect of the essential ability to charm.
Like every other human activity, flirting is governed by a complex set of unwritten laws of etiquette.
These rules dictate where, when, with whom and in what manner we flirt.
Chatting up a widow at her husband's funeral, for example, would at the very least incur disapproval, if not serious distress or anger.
So, to save the human race from extinction, and preserve the foundations of civilisation, Martini commissioned Kate Fox at the Social Issues Research Centre to review and analyse all the scientific research material on interaction between the sexes, and produce a definitive guide to the art and etiquette of enjoyable flirting.
We generally obey these unofficial laws instinctively, without being conscious of doing so.
We only become aware of the rules when someone commits a breach of this etiquette – by flirting with the wrong person, perhaps, or at an inappropriate time or place.
Psychologists and social scientists have spent many years studying every detail of social intercourse between men and women.
Until now, their fascinating findings have been buried in obscure academic journals and heavy tomes full of jargon and footnotes.