A new film, called Bounce, aims to answer the question: Why do we play ball?
The film, which is due to be released later this year, begins and ends in Orkney, where the traditional game of ba is still played in Kirkwall at Christmas and New Year's Day.
Ba dates back to the mid-17th century and is played between two teams: the Uppies and the Doonies. It can involve as many as 350 men in a confusing but spectacular effort to carry the ba' from one part of the town to another.
A clip from the film, featuring the Kirkwall Ba, can be viewed below.