Biologists have found evidence that people can sniff out the chemical signals of sexual attraction.
Many animals respond to chemical sex signals, or pheromones
A US team has discovered a new class of receptors used by mice to detect pheromones, the sex hormones released by a potential mate.
The gene for the receptors is also found in humans, suggesting that they too may be influenced by chemicals used in the dating game.
The findings are published in the online edition of the journal Nature.
Mice, like other mammals, can detect many different odours using receptors attached to special cells in the lining of the nose.
When an odour locks on to the receptor, a signal is sent to a processing centre in the brain, which perceives it as a specific smell.
Mammals have as many as 1,000 different odour receptors, giving them the ability to detect and discriminate a wide range of smells.
Now, researchers have discovered a new family of receptors that are located in the nasal lining of the mouse. These respond to volatile natural chemicals called amines, which are derivatives of ammonia.
The receptors, known as trace amine-associated receptors (TAAR), detect several chemicals present in the urine of mice, including one linked to stress and another thought to be a mating signal.
The gene that codes for the receptor is found not only in mice but in fish and humans, suggesting that the behaviour of a diverse group of animals is influenced by pheromones.
The sensory receptors were tracked down by Dr Linda Buck and Dr Stephen Liberles of the Fred Hutchinson Cancer Research Center in Seattle, Washington, US.
Dr Buck won the 2004 Nobel Prize in Physiology or Medicine for her discoveries on odour receptors and the organisation of the olfactory system.