New facilities at the Lucas Heights Science and Technology Centre that enabled the carbon dating of tiny samples of rock art from Vanuatu are shedding light on Pacific migration, while demonstrating a method of dating samples that reduces the impact on culturally and historically valuable items.
Working in conjunction with the native people in Vanuatu, scientists from the Australian Nuclear Science and Technology Organisation (ANSTO) have demonstrated how they can analyse tiny samples of rock art that once would have been unusable for analysis.
Results of carbon dating 57 samples of paintings from 14 caves on the island of Malakula show a rapid and marked increase of rock paintings 1500 years ago, signalling what archaeologists believe may have been stronger territoriality associated with increasing populations.
This information adds to the scientific knowledge about migrations in the Pacific and Indian Oceans, which constitute the earliest known cross oceanic diasporas and furthest-ranging maritime migrations prior to the relatively recent migrations from Europe. The last 200 years is again marked by an increase in the incidence of rock art, in response to these modern territorial intrusions.
As part of the Vanuatu study, ANSTO scientists demonstrated new laboratorybased techniques, which mean they can effectively use samples as small as 10 micrograms of carbon - equivalent to 100,000th of a gram. Further technical development is under way to make it possible to analyse samples as small as 5 micrograms.
According to Dr Ugo Zoppi of ANSTO Physics, this work has involved the development of new equipment for preparing very small samples in the chemical laboratory, a further reduction of the contamination introduced during pretreatment, as well as new procedures for measuring samples.
These new techniques mean that researchers will be able to analyse more specific samples such as selected seeds, pollen grains and specific amino acids from bone or blood samples. ANSTO is currently amongst a select group of institutions capable of analysing these small samples.
Carbon dating involves the analysis of Carbon 14, which is found in one part for every trillion (one thousand billion) or less of Carbon 12,
the most abundant carbon isotope. These measurements are overseen by ANSTO's Accelerator Mass Spectrometry group. AMS is an ultrasensitive analytical technique based on the use of an ion accelerator such as ANSTO's Australian National Tandem Accelerator for Applied Research (ANTARES).