When it comes to picking sports teams in the playground, children have long opted for best friends instead of their most talented classmates.
But a study suggests that favouring friendship over merit doesn't necessarily damage chances of sporting success.
This is because children who are chosen by friends feel indebted and improve their performance, according to research.
Scientists studied 256 children aged six to eight and ten to 12 in nine schools who competed in teams in a game which involved bringing balls from one basket to another for 30 seconds.
They then had to choose which boy or girl they wanted to do the task with in the second round "for the benefit of the team".