Rock art sites contain some of the world's greatest works of art, aesthetically powerful and spiritually charged imagery embedded in cultural landscapes. Rock art is found worldwide, but both Australia and southern Africa each have at least 100,000 rock art sites and many new discoveries are made globally each year. The oldest surviving Australian and African rock art is at least 28,000 years of age (David et al. 2013; Wendt 1976), while in Spain and parts of Southeast Asia there are images closer to 40,000 years old (Aubert et al. 2014; Pike et al. 2012). In many parts of the Americas, Australia, Africa and Asia, rock art continued to be made until very recently; in some places, such as Australia's Kakadu National Park, some form of pigment-based art appears to have been made continuously from when humans first arrived to the present (Taçon 2011).