Old Art

Today’s Nature magazine (514, 223-237) has an article by M Aubert et al which dates newly discovered pictures found at Indonesian caves. Uranium isotope dating of coralloid speleothems shows they are 39,900 years old

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Seven caves at Maros, on the island of Sulawesi, have twelve human hand stencils and two figurative animal depictions of pig-deer, 35,400 years old.

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Homo sapiens is thought to have migrated across South Asia and the Far East to Australasia about 50,000 years ago. Meanwhile, in Europe, similar stencils and other images have been dated between 35,000 and 40,000 years. The latest discoveries show that human art thrived around 40,000 at opposite ends of Pleistocene Eurasia. What other discoveries are in store?

Wikipedia tells us that uranium-uranium dating is a radiometric dating technique which compares two isotopes of uranium (U) in a sample: 234U and 238U. Unlike other radiometric dating techniques, those using the uranium decay series  compare the ratios of two radioactive unstable isotopes. This complicates calculations as both the parent and daughter isotopes decay over time into other isotopes. In theory, the 234U/238U technique can be useful in dating samples between about 10,000 and 2 million years old.