Roberts, Richard; Walsh, Grahame; Murray, Andrew; Olley, Jon; and others.
Luminescence dating of rock art and past environments using mud-wasp nests in northern Australia.
Nature 387. 6634 (June 12, 1997): 696 (4 pages).

Abstract
Optical luminescence dating of pollen grains in the nests of mud-wasps in Northern Australia has been used to estimate the minimum age of aboriginal cave paintings. The ants scoop quartz-containing river muds and build nests on the rocks, some of which bear paintings. Some of the paintings in Australia's Kimberley region have been estimated to be at least 17,000 years old using the technique. It is expected that analysis of other paintings will show them to be considerably older. Optical dating measures the time since the quartz was last exposed to sunlight.