What do Maori haka, Fijian firewalking and yoga have in common? According to a book by Canadian writer Andrew Potter (The Authenticity Hoax, Scribe, $40) they are all part of an authenticity hoax. People try to avoid the fake and the prepackaged by demanding authenticity, yet these activities exacerbate the artificiality people seek to escape. This extract looks at how the authenticity hoax operates in the world of tourism.

On the western edge of downtown Mexico City sits Chapultepec Park, a 988-acre oasis of trees, playing fields, and gardens that is one of the world's outstanding urban playgrounds. And one of the great attractions in Chapultepec itself is the Museo Nacional de Antropologa, a museum that contains a seemingly endless succession of exhibition halls, each dedicated to a separate period or culture in Mesoamerican history.

Just off the plaza that dominates the entrance to the museum is a dirt-covered clearing ringed with benches. At the centre is a 65-foot-high metal pole with a platform on top. This clearing is where tourists gather to see the dance of the Voladores, an ancient pagan rite performed by Totonac Indians from the Papantla region of Mexico.

For the performance, five men dressed in brightly coloured traditional costumes climb to the top of the pole. Four of them tie to their ankles thick ropes that have been wound around the top of the pole, then fling themselves off headfirst and backwards, like scuba divers. As the ropes unwind, the four Voladores spiral to the ground in slowly expanding circles, while the leader of the group, plays a drum, a flute, and prays to the fertility gods. While all of this is going on, a handful of assistants - clad in the same traditional get-up - canvass the crowd for donations.

No one knows for sure the origins or full significance of the ritual. This is partly because the Spaniards made a point of destroying all of the indigenous documentation, but also because these same Spaniards were quite sure it was not a religious ceremony but some sort of sport.

The upshot, anyway, is that the dance of the Voladores is a living artifact, a museum piece as frozen and uncertain as the masks and figurines and objects that fill the Museo Nacional de Antropologa itself.

This is far from an isolated phenomenon. Just about every place worth visiting makes a point of promoting a preserved form of its supposedly pure and undiluted cultural past to tourists. Often it involves aboriginal groups: singing and drumming by the Cowichan people on Vancouver Island, for instance, or Maori dancing in body paint and traditional clothes in New Zealand.

But you can also go to resorts in the Caribbean where they all dance around with fruit on their head even though you know darn well that no one carries fruit on their head in the city. Or you can visit the Jewish quarter in Krakow to drink kosher vodka and listen to Klezmer music played by university students from Toronto.