I discussed this with an anthropologist many moons ago - their hypothesis was that humans are intrinsically pack animals and they have a natural desire and compulsion to near others. Goes back to the old 'strength in numbers' instinct.

In the same vein he also put forward a suggestion for why, in a couple, the man will often sleep in the side of the bed nearest the door. Completely subconcious, but harks back to cave living and having your family behind you so you can protect them.

Could all be tosh though smile

"Y mae dafad ddu ym mhob praidd"
1972 4/4, 1981 MGBGT, 1984 FLHT1340, 1980 XLH1000, 1990 ZX10