People willing to pay painful price for friendship

People will suffer more pain for their close friends than for their acquaintances and sometimes more than they would for themselves, an Oxford University scientist has found. Dr Freya Harrison of Oxford University's Department of Zoology asked 19 members of a research group at the University to squat against a wall with knees at right angles - a ski training exercise which becomes increasingly painful with time.Individuals performed the exercise five times, once for themselves and once for four different colleagues, to whom they claimed varying strengths of social tie. They were paid 1p per second squatted and were asked to perform the exercise for as long as they wanted. When close friends won the money, people squatted for much longer than when they squatted for acquaintances - and often squatted longer (on average around 1.5 times longer) for their closest friends than when they were paid the money themselves. The study by Dr Harrison and colleagues at the University of Bath, published in this week's PLoS ONE , is thought to be one of the first to measure co-operation between friends and colleagues rather than between strangers. The researchers believe that, in humans, social ties increase co-operation, a finding that echoes similar studies on other species. For example: the guppy, a popular aquarium fish, works most closely on predator look-out duties with other guppies with which it has social ties.