Friends rather than family are more likely to affect how we behave and develop, according to scientists who have been studying the behaviour of macaque monkeys.
Jerome Micheletta and Dr Bridget Waller, of the University of Portsmouth's Department of Psychology, have found that the primates are more responsive to the actions of friends than relatives.
They believe that the strength of this bond of friendship could explain how other primates, including humans, develop their social skills.
Mr Micheletta, a PhD student, has been studying the gaze-following - looking where a companion is looking - amongst a group of macaques at Marwell Wildlife in Hampshire.
He explained that gaze-following is seen as a 'key marker of social development' as it is a way of obtaining information about what is happening around them.
Mr Micheletta said that although the macaques followed the gaze of another regardless of their status as a friend, family member of dominant member, they responded much more quickly if it was a friend.
He said: 'Our findings reveal something about the evolution of friendship and its links with cognition and communication, which have not been studied before.
'Our study shows that friendship, more than family ties or the status of another, improves the gaze-following ability of this particular macaque species.
'It is likely the same applies to other primates, including humans.'
Mr Micheletta said that the research, published in the journal Animal Behaviour, showed that gaze-following was not used randomly.
He said: 'Macaques follow the gaze of others in order to cope with a complex and challenging social life.
'It is thought gaze-following - which occurs even when the 'gaze' is an almost imperceptible eye movement - helps individuals learn valuable things about their social and physical environment by providing clues about the location of something interesting, whether that be food, a threat or something else.
'Our main finding is that gaze-following is strongly influenced by the degree of friendship between the macaques.
'Friends did not react more often to the gaze of those who weren't friends, but reacted much faster to friends' gazes regardless of the subtlety or lack of it in the informants' movements.
'Our results suggest that this effect of friendship seems independent of social status and family relationships.'
Mr Micheletta explained that it was not known why macaques follow the gaze of a friend more swiftly but said: 'One possible reason for this could be that information gained from a friend is likely to be more relevant and useful to the gaze follower.
'Rapidly following the gaze of another might be advantageous in many ways - finding a resource such as food is more likely if competition between friends is reduced, and an individual is more likely to be more concerned about any social event involving a friend.
'This is partly so they can help support each other during conflict which helps build social cohesion and stability.'