<Tr> <Th> Paralympic </Th> <Td> Wheelchair curling officially added in 2006 . </Td> </Tr> <P> Curling is a sport in which players slide stones on a sheet of ice towards a target area which is segmented into four concentric circles . It is related to bowls, boules and shuffleboard . Two teams, each with four players, take turns sliding heavy, polished granite stones, also called rocks, across the ice curling sheet towards the house, a circular target marked on the ice . Each team has eight stones, with each player throwing two . The purpose is to accumulate the highest score for a game; points are scored for the stones resting closest to the centre of the house at the conclusion of each end, which is completed when both teams have thrown all of their stones . A game usually consists of eight or ten ends . </P> <P> The curler can induce a curved path by causing the stone to slowly turn as it slides, and the path of the rock may be further influenced by two sweepers with brooms who accompany it as it slides down the sheet, using the brooms to alter the state of the ice in front of the stone . Sweeping a rock makes it curl less, and decreases the friction that slows the rock down . A great deal of strategy and teamwork go into choosing the ideal path and placement of a stone for each situation, and the skills of the curlers determine the degree to which the stone will achieve the desired result . This gives curling its nickname of "chess on ice". </P> <P> Evidence that curling existed in Scotland in the early 16th century includes a curling stone inscribed with the date 1511 uncovered (along with another bearing the date 1551) when an old pond was drained at Dunblane, Scotland . The world's oldest curling stone and the world's oldest football are now kept in the same museum (the Stirling Smith Art Gallery and Museum) in Stirling . The first written reference to a contest using stones on ice coming from the records of Paisley Abbey, Renfrewshire, in February 1541 . Two paintings, "Winter Landscape with a Bird Trap" and "The Hunters in the Snow" (both dated 1565) by Pieter Bruegel the Elder depict Flemish peasants curling, albeit without brooms; Scotland and the Low Countries had strong trading and cultural links during this period, which is also evident in the history of golf . </P>

What olympic sport is also known as ice chess