Humans have been fascinated with contacting the dead since the beginning of human existence. Cave paintings by indigenous Australians date back 28,000 years, some depicting skulls, bones, spirits and the afterlife. Other cave paintings in Indonesia date back a further 10,000 years. Mediumship gained popularity during the nineteenth century, when ouija boards were used by the upper classes as a source of entertainment. Investigations during this period revealed widespread fraud—with some practitioners employing techniques used by stage magicians—and the practice began to lose credibility. Fraud is still rife in the medium/psychic industry, with cases of deception and trickery being discovered to this day.