Hairy skin has soft touch nerves

Foreplay is usually off-limits in laboratories. But for a group of Swedes it's all in a day's work. They have found that a special nerve type senses tender touch.

The team studied a woman whose main touch nerves have been killed by disease. She cannot feel a prod, but can detect the light stroke of a paintbrush on her arm - rating it as "pleasant"1.

Using brain imaging, they found that slow stroking stimulates a brain area that deals with emotions, love and sexual arousal.

The nerves "are responsible for the pleasant aspects of touch", says team leader Hakan Olausson of Sahlgrenska University Hospital in Gothenburg. These are distinct from another nerve type that discriminates shape and vibration.

Olausson is stumped as to why we - and other mammals - have special 'soft touch' nerves.

There is some evidence that touch is important for survival - experiments in the 1950s showed that baby monkeys removed from their mothers choose a cloth surrogate over a wire one that provides milk. Gentle touch could release hormones or alter our behaviour. "They can serve the sense of well-being," Olausson suggests.

The sensitive nerves lie under hairy skin - that is, everywhere but the palms of the hands and soles of the feet. Lovers take note: "If you stroke too fast they will not respond," says Olausson.