NOTWITHSTANDING the example of Robert Burns and his romantic poetry, Scotsmen are better known for their ability as warriors than for being romantic lovers.

However, the evidence from the marriage of Robert Louis Stevenson, the author of Treasure Island and Dr Jekyll and Mr Hyde, shows that this was also untrue in his case. A new biography by Claire Harman reveals that throughout his short life — he died at the age of 44 — Stevenson remained devotedly and romantically in love with his wife despite her promiscuous behaviour.

The scientist Dr George Dodd, who lives and works by the sea in the Scottish Highlands, would at first sight seem to epitomise the Stevenson image of the romantic but pragmatic Scotsman, with his knotted beard and long hair (although he is in fact Irish). Dr Dodd has been studying human nature and the physical influences that determine our behaviour. He has examined the olfactory system that controls the sense of smell and has made the effect of smell on human libido — sexual desire — his special subject.

He has developed a scent called Scentuelle which contains hundreds of odiferous molecules that mimic the effect of the brain chemical dopamine. It is generally accepted that there is an association between scents and mood, and that dopamine levels influence sexual drive. This effect was obvious to doctors when levodopa, a precursor of dopamine, was first used as replacement therapy in Parkinson’s disease. Later, one pharmaceutical company carried out investigations into dopamine as an aid to loss of libido but was unable to overcome the difficulties caused by adverse side-effects.

These are not a problem with Scentuelle, which reaches the brain through the olfactory system rather than via the bloodstream: the smell-carrying molecules pass through the olfactory epithelium and along the olfactory nerves to the olfactory bulb and the smell receptors, which make contact with the limbic system in the brain without entering the bloodstream, so there is no possibility of side-effects.

Dr Dodd claims that if women regularly sniff a patch impregnated with a solution of Scentuelle it will work wonders for those who suffer from a lack of sexual desire.

Statistics quoted in a study from the American Medical Association in 1999 suggested that up to 35 per cent of women had a low libido. The prevalence of sexual dysfunction in women is disputed but to judge from my experience in a genitourinary medical clinic, there is no doubt that some women are troubled by a lack of sexual interest, let alone desire.

Scentuelle is not a pheromone (these are the substances released subconsciously by the sweat glands of one person or animal to attract another). But just as dopamine is produced by the patient and acts on her own system, when a woman sniffs the impregnated Scentuelle patch on her wrist she is likewise helping to stimulate her sex drive.

It is said that the patch begins to work from the first sniff but that the effect is cumulative, reaching optimum level only after two weeks. The patch, which is almost invisible, should be sniffed every hour. It may be getting too late for a patch fully to influence the course of a Valentine’s dinner but it still offers a better bet than oysters.

The same principle would work for men, although Dr Dodd is currently working on a method of delivery that they would find more acceptable.

Mrs Fanny Stevenson, Robert Louis’s wife, needed neither scents that mimic dopamine nor, so far as we know, oysters to stimulate her libido — the pheromones from the sweat glands of a man’s scalp, ears, eyelids and, especially, his groin, armpits and chest provided enough stimulation naturally. But there are thousands who, unlike Fanny, could benefit from some additional help.

• Robert Louis Stevenson by Claire Harman (HarperCollins, £25).

  Scentuelle is available through mail order at £19.95 incl. p&p: 08700 625746 or visit www.scentuelle.com