The complete title of BAR S2108 is 'Methods of art history tested against prehistory: session C74. Spiral and circular forms: the most common rock art in the world?: session C81. European cave art: session C85. Euro-Mediterranean rock art studies: session S02. Global state of the art: session S07. Current state of North American rock art: session WS37'. Proceedings of the XV UISPP World Congress (Lisbon, 4-9 September 2006), Vol. 35.