Pheromones and smells

Pheromones and smells

Why are you attracted to one person and not another? Do you choose a partner for their smell? Could the answers lie in pheromones?

Pheromones are chemical signals that change an animal's behaviour without the animal being aware of it. Pheromones are often involved in sexual behaviours.

Whereas animals and people consciously appreciate smells - they'll have a good sniff, or turn away in disgust - pheromones are not consciously perceived. They change an animal's behaviour in an unconscious and involuntary way.

Pheromones were first discovered 50 years ago in insects and scientists know that mice use them. However, until recently there has been no evidence that humans use pheromones in any way.

Now scientists at Rockefeller University and Yale University think they have identified a human gene linked to pheromones.

The gene, named V1RL1, is the first to be reported in humans. The researchers believe it makes a protein that will detect pheromones. They suspect this 'pheromone receptor' is in the mucus membranes lining the human nose. More work is needed to discover what exactly this receptor might do and if it can influence human sexual behaviour.

Testing our visitors with pheromones
In the Your Amazing Brain exhibition in Bristol, UK, we've tested our visitors with a pheromone called androstenone. This pheromone is produced by men and is now sold over the internet as 'date-mate - a spray which guarantees to make you irresistible to women.'

Thousands of our visitors have given their opinion on androstenone. This is what they said:

	Males	Females
It smells like urine	22%	23%
It smells musky	38%	35%
It smells nice	8%	6%
It smells bad	21%	26%
I couldn't smell it	11%	10%

So… with androstenone, will women find you irresistible?
Although there seems no real evidence that androstenone attracts women, sales of the androstenone spray seem to be doing well.

Scientists do know that this pheromone excites pigs. Androstenone is found in truffles, which is why pigs will spontaneously search for them and why dogs can be taught to find them.

So… will androstenone make you irresistible to women? No, it seems not - unless of course you are irresistible already!

How do mammals detect pheromones?
Most mammals have a gland at the top of their nose, called the vomeronasal organ. Scientists believe this detects the sex pheromones and triggers an involuntary response, for example, getting sexually excited.

However, in humans, there's no really good evidence that we have a vomeronasal organ. The question of whether we act involuntarily to pheromones is still unanswered.

Funky pheromone facts

Over-kill!
A single female Bombay moth carries more than 1.5ug of pheromone at any one time. This is enough to lure 1 billion billion males at close range!

Long-range
The silkworm moth can detect pheromones from other silkworms up to 11km away. The moths immediately fly towards the source.

Detectors
Male moths detect pheromones through their antennae. A male fly detects pheromones through its front legs.

Irresistible
Imagine a tiny drop of water small enough to fit on a pinhead - and divide that by 1000. You are left with a droplet weighing about 0.004 micrograms and invisible to the naked eye.
Scientists have discovered that in female flies, this amount of purified sex hormone will attract 500 - 1000 male flies from 150 feet in just 5 minutes.

Are women attracted to men's sweat?
There is some evidence that women are attracted to the sweat of men who have a different tissue type to them. This would promote genetic mixing and be desirable in genetic terms. However, the sweat must be very fresh!

Look out for … Vanilla

What is the effect of vanilla on humans? Its structure is very similar to testosterone but its effects are unknown.