Ancient cultural burning practices carried out by Indigenous Australians limited fuel availability and prevented high intensity fires in southeastern Australia for thousands of years, according to new research from The Australian National University (ANU) and the University of Nottingham.
The research, published in Science, highlights how the intensity of forest fires in fire-prone southeastern Australia decreased over time alongside an increase in Indigenous populations in the area.
Dr Simon Connor from ANU said a better understanding of the link between human-induced climate change and the projected rise in the frequency and intensity of forest fires will lead to improved forest management and conservation in Australia.
“We often think about forests and woodlands in terms of trees, but this research shows that some of the biggest changes have happened not in the tree canopy but in the shrub layer. That's something we weren't expecting to find,” he said.
“Indigenous peoples have shaped Australian landscapes over tens of thousands of years. They did this through cultural practices. We need to keep that in mind when we're thinking of the best way to live in the Australian environment.”
Using tiny fossils preserved in ancient sediment, the research team reconstructed ancient landscapes across southeastern Australia to understand how the vegetation has changed over time.
The researchers focused on the shrub layer because this is what allows flames to climb from the ground to the canopy, leading to high intensity fires.
The team then compared this with archaeological data to analyse how human activity has impacted levels of shrub cover in Australian landscapes over time.
Lead researcher Dr Michela Mariani, from the University of Nottingham, said the expansion of Indigenous populations and a subsequent increase in the use of cultural burning led to a 50 per cent decrease in shrub cover, which in turn led to a decline in high intensity fires.
“The shrub layer in forests can often act as ladders for wildfires to climb up to tree canopies and spread,” Dr Mariani said.
“Following British colonization and extensive fire suppression, shrub cover in Australia has increased to the highest ever recorded, which significantly increases the risk of high intensity fires in the future.
“Australia’s fire crisis can be tamed with the involvement of Indigenous practitioners in fire management. It’s important to rekindle ancient cultural burning practices together with Traditional Owners to reduce the risk of catastrophic blazes.”
This work also involved researchers from the University of Melbourne, Monash University and the University of Tasmania.
Genetic study of the wider Caucasus region shows how movement of people and innovation transfer enabled pastoralists to exploit the steppe zones of Eurasia
Max Planck Institute for Evolutionary Anthropology
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Burial mounds are the most emblematic archaeological monuments of Bronze Age Eurasia. In the Caucasus Mountains, they were built up to great heights and mark the communication networks through which knowledge and innovations were transmitted.
The wider Caucasus region, between the Black and the Caspian Seas, connects Europe, the Near East and Asia. It displays a huge geographic, ecological, economic, cultural, and linguistic range today, from the steppe zone in the north, the Caucasus mountains in the center, to the highlands of today’s Armenia, Georgia, Azerbaijan and Iran in the south. This diversity was no different in the past, where the archaeological record attests to many different influences from many surrounding regions.
“It is precisely this interface of different eco-geographic features and archaeological cultures that makes the region so interesting to study”, explains Dr. Wolfgang Haak, senior author and principal investigator of the study. “By establishing a time series across many consecutive archaeological periods, we wanted to capture the time periods when, for example, the first farmers arrived in the region, or when the combination of new innovations in e.g., herd management, dairying, and mobility, enabled an autonomous nomadic lifestyle adapted to exploit the vast Eurasian steppe zone”.
The team observes an alternating series of interaction and gene flow between inhabitants of the major eco-geographic zones of the mountainous upland regions and the steppes to the north of the Caucasus. “Initially, we find two distinct genetic ancestries among the hunter-gatherer groups north and south of the Greater Caucasus”, adds lead author Ayshin Ghalichi, PhD candidate at the Max Planck Institute for Evolutionary Anthropology in Leipzig.
This picture changed with the arrival of early farmers from northern Mesopotamia in the 6th millennium BC, which led to two initial processes of mixture: one between these early farmers farmers and Caucasus/Iranian hunter-gatherers, which formed the predominant ancestry south of the Caucasus mountains, and a second one between the aforementioned hunter-gatherer groups, which resulted in the ancestry profile in the steppe zone north of the Caucasus. During the following 5th and 4th millennium BC, Eneolithic cultures emerged in the river valleys of the North-Pontic steppe and became archaeologically visible as they built characteristic earthen burial mounds, known as ‘kurgans’. New Eneolithic groups arriving from the south led to a period of contact and exchange between both groups and resulted in the emergence of the Maykop culture phenomenon in the 4th millennium BC, which represents a horizon of technical and social innovations in archaeology.
Into the great wide open
“This is a peak time of knowledge and technology transfer in the North Caucasus region, when we see very similar cultural elements in genetically different groups, but also many signs of mixing and mingling”, explains Dr. Sabine Reinhold, co-lead author and principal investigator at the German Archaeological Institute in Berlin. “We uncover the moments when groups began to adapt their lifestyle to a more mobile economy, more suitable to the seemingly endless grasslands of Eurasia.” Indeed, the archaeological record attest to critical innovations in herd management, dairying practices, and mobility such as wheels and wagons, of mobile architecture, and the incipient horse domestication, besides many more. “The global dairy industry today is built on the back of these Bronze Age innovations,” says Prof. Christina Warinner, co-author and professor of anthropology at Harvard University. “They turned a somewhat niche practice into a multicontinental phenomenon.”
Durable foodstuffs such as the early forms of cheese, together with innovations in transportation, made it possible to populate the Eurasian steppe permanently and establish continent-wide networks of communication. The combination of innovations paved the way for a fully nomadic pastoralist life-style at the turn the 3rd millennium BC, practiced for instance by groups associated the Yamnaya cultural complex, which soon after expanded across the entire western steppe zone, as far as Mongolia in the east, and the Carpathian Basin in the west. Interestingly, it was also a time when Caucasus groups expanded to the south, such as the Kura-Araxes culture of Georgia, which extended to regions in east Anatolia, the Levante, and Iran, albeit with little or no connections to the steppe zone in the north.
The team also explored the social structure of prehistoric groups by analysing patterns of biological relatedness and consanguinity and found differences between the steppe and the Caucasus groups. The more stationary Caucasus groups showed higher levels of consanguinity and close connections between individuals buried in the same and/or nearby kurgans, whereas the steppe groups revealed very few of such connections, hinting at a different form of social organization of mobile pastoralist groups.
Dissolution and transformation
However, the turn to the 2nd millennium BC represents another period of interaction between the steppe and Caucasus populations. Triggered by a period of aridification and possibly over-exploitation of the ecologically fragile steppe environment and unreliable levels of precipitation, the steppe zone became largely depopulated. The archaeogenetic study finds clear evidence of assimilation and mixture of Caucasus groups, while the resulting Middle and Late Bronze Age groups retreated further into the Caucasus highlands where they established a sedentary mountain economy. This transformation also formed the cultural and genetic basis for the present-day populations of the North Caucasus.
“Our integrated study is a beautiful example of human resilience, adaptability and innovation in the light of ecological, economic and socio-political changes”, concludes Prof. Svend Hansen, director of the Eurasia Department of the German Archaeological Institute, and co-senior author of the study.
Credit: Charloux et al., 2024, PLOS ONE, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)
Settlements in northern Arabia were in a transitional stage of urbanization during the third to second millennium BCE, according to a study published October 30, 2024 in the open-access journal PLOS ONE by Guillaume Charloux of the French National Center for Scientific Research, Paris and colleagues.
The development of large urban settlements was a major step in the evolution of human civilization. This process of urbanization has proven difficult to study in northern Arabia, due in part to a lack of well-preserved archaeological sites in the region compared with better understood areas such as the Levant and Mesopotamia. In recent decades, however, excavations have uncovered exceptional sites in northern Arabia that provide insights into the early stages of urbanization.
In this study, Charloux and colleagues provide a detailed description of the Bronze Age town of al-Natah in Medinah province, occupied from around 2400-1500BCE. The town covered approximately 1.5 hectares, including a central district and nearby residential district surrounded by protective ramparts. A cluster of graves represents a necropolis, with burial practices indicating some degree of social stratification. The authors estimate the town was home to around 500 residents. The size and organization of al-Natah is similar to other sites of similar age in northern Arabia, but these sites are smaller and less socio-politically complex than contemporary sites in the Levant and Mesopotamia.
The researchers suggest that al-Natah represents a state of ‘low urbanization,’ a transitional stage between mobile pastoralism and complex urban settlements. Archaeological evidence so far indicates that northern Arabia was dotted with small fortified towns during the Early-Middle Bronze Age, at a time when other regions exhibited later stages of urbanization. Further excavations across Arabia will provide more details about the timing of this transition and the accompanying changes in societal structure and architecture.
The authors add: “For the first time in north-western Arabia, a small Bronze Age town (c. 2400-1300 BCE) connected to a vast network of ramparts has been discovered by archaeologists, raising questions about the early development of local urbanism.”
