A new study, reported in the Journal of Archaeological Science, explores behavior of Aboriginal Australians during the Last Glacial Maximum (LGM for short).

“The period scientists call the Last Glacial Maximum is the most significant climatic event ever faced by humans on this continent. The magnitude of change was phenomenal. Lakes dried up, forests disappeared, deserts expanded, animals went extinct and vast swathes of the Australian land mass would have been simply uninhabitable,” said Prof Sean Ulm from James Cook University in Cairns, who is a second author of the study.

Annual temperatures plummeted by as much as 10 degrees below present-day levels, with massive reductions in rainfall. Glaciers appeared in the Snowy Mountains and Tasmania.

“This was a time of massive change. Sea levels fell more than 120 metres during the LGM, exposing much of the continental shelf and connecting mainland Australia to Papua New Guinea and Tasmania.”

Prof Ulm and his Australian colleagues teamed up with scientists from the United Kingdom and Canada to use advanced geospatial techniques to analyze archaeological radiocarbon dates from across Australia.

“We are trying to understand how people responded to these extreme conditions,” Prof Ulm said.

The team found that during times of high climatic stress, human populations contracted into localized environmental ‘refuges’, in well-watered ranges and along major riverine systems, where water and food supplies were reliable.

“Surviving the last ice age required Aboriginal communities to adapt to massive change,” said study lead author Dr Alan Williams from the Australian National University.

“As much as 80 per cent of Australia was temporarily abandoned by Aboriginal people at the height of the LGM, when conditions were at their worst. Along Australia’s east coast, people contracted to refuge areas with good water supplies – most likely the result of increased summer snow melt coming off mountain ranges like the Victorian Alps, or glacier-fed river systems such as those of the central highlands of Tasmania.”

Prof Ulm added that while those better-watered areas would have provided more reliable resources, Aboriginal people needed to make significant changes to their way of life in order to survive.

“The archaeological evidence reflects major changes in settlement and subsistence patterns at this time. Many previously occupied areas were abandoned. There were changes to hunting practices, the types of food people were eating, and the technologies they were using, to deal with new circumstances.”

“We expect there would have been huge impacts on social relationships and religious beliefs as well, but these types of changes are much harder to detect in the archaeological record. One thing we can say for sure is that extreme climate change results in the fundamental social and economic reorganisation of society. This was certainly true in the past and will be true in the future.”

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Bibliographic information: Alan N. Williams et al. 2013. Human refugia in Australia during the Last Glacial Maximum and Terminal Pleistocene: a geospatial analysis of the 25–12 ka Australian archaeological record. Journal of Archaeological Science, vol. 40, no. 12, pp. 4612–4625