People once lived in a vast region in north-western Australia – and it had an inland sea

21 12 2023

For much of the 65,000 years of Australia’s human history, the now-submerged northwest continental shelf connected the Kimberley and western Arnhem Land. This vast, habitable realm covered nearly 390,000 square kilometres, an area one-and-a-half times larger than New Zealand is today.

Overhead image of a coastline with modern day outlines and what it used to look like
Left: Satellite image of the submerged northwest shelf region. Right: Drowned landscape map of the study area. US Geological Survey, Geoscience Australia

It was likely a single cultural zone, with similarities in ground stone-axe technology, styles of rock art, and languages found by archaeologists in the Kimberley and Arnhem Land.

There is plenty of archaeological evidence humans once lived on continental shelves – areas that are now submerged – all around the world. Such hard evidence has been retrieved from underwater sites in the North Sea, Baltic Sea and Mediterranean Sea, and along the coasts of North and South America, South Africa and Australia.

In a newly published study in Quaternary Science Reviews, we reveal details of the complex landscape that existed on the Northwest Shelf of Australia. It was unlike any landscape found on our continent today.

A continental split

Around 18,000 years ago, the last ice age ended. Subsequent warming caused sea levels to rise and drown huge areas of the world’s continents. This process split the supercontinent of Sahul into New Guinea and Australia, and cut Tasmania off from the mainland.

Unlike in the rest of the world, the now-drowned continental shelves of Australia were thought to be environmentally unproductive and little used by First Nations peoples.

But mounting archaeological evidence shows this assumption is incorrect. Many large islands off Australia’s coast – islands that once formed part of the continental shelves – show signs of occupation before sea levels rose.

Stone tools have also recently been found on the sea floor off the coast of the Pilbara region of Western Australia.

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New job posting: Research Fellow in Eco-Epidemiology & Human Ecology

11 05 2023

We are currently seeking a Research Fellow in Eco-epidemiology/Human Ecology to join our team at Flinders University.

The successful candidate will develop spatial eco-epidemiological models for the populations of Indigenous Australians exposed to novel diseases upon contact with the first European settlers in the 18th Century. The candidate will focus on:

  • developing code to model how various diseases spread through and modified the demography of the Indigenous population after first contact with Europeans;
  • contributing to the research project by working collaboratively with the research team to deliver key project milestones;
  • independently contributing to ethical, high-quality, and innovative research and evaluation through activities such as scholarship, publishing in recognised, high-quality journals and assisting the preparation and submission of bids for external research funding; and
  • supervising of Honours and postgraduate research projects.


The ideal candidate will have advanced capacity to develop eco-epidemiological models that expand on the extensive human demographic models already developed under the auspices of the Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage, of which Flinders is the Modelling Node. To be successful in this role, the candidate will demonstrate experience in coding advanced spatial models including demography, epidemiology, and ecology. The successful candidate will also demonstrate:

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Remapping the superhighways travelled by the first Australians reveals a 10,000-year journey through the continent

3 02 2023

Not exactly a conservation topic, I know, but it does provide insights into how the ancestors of Indigenous Australians adapted to and thrived in a new and sometimes harsh landscape. The more I study elements of human ecology in deep time, the more awed I become at the frankly amazing capacity of First Peoples.


Our new research (co-authored by Stefani Crabtree, Devin White, Sean Ulm, Michael Bird, Al Williams, and Fred Saltré) has revealed that the process of peopling the entire continent of Sahul — the combined mega continent that joined Australia with New Guinea when sea levels were much lower than today — took 10,000 years.  

We combined new models of demography and wayfinding based on geographic inference to show the scale of the challenges faced by the ancestors of Indigenous people making their mass migration across the supercontinent more than 60,000 years ago.

The ancestors of Aboriginal people likely first entered the continent 75,000–50,000 years ago from what is today the island of Timor, followed by later migrations through the western regions of New Guinea.

This pattern led to a rapid expansion both southward toward the Great Australian Bight, and northward from the Kimberley region to settle all parts of New Guinea and, later, the southwest and southeast of Australia.

We did this research under the auspices of the ARC Centre of Excellence for Australian Biodiversity and Heritage (CABAH) and including international experts in Australia and the United States to investigate the most likely pathways and the timeframe needed to reach population sizes able to withstand the rigours of their new environment.

By combining two existing models predicting the routes these First Peoples took – ‘superhighways’ – and the demographic structure of these first populations, we were able to estimate the time for continental saturation more precisely. The new research has just been published in the journal Quaternary Science Reviews.

Based on detailed reconstructions of the topography of the ancient continent and models of past climate, we developed a virtual continent and programmed populations to survive in and move successfully through their new territory.

Navigating by following landscape features like mountains and hills and knowing where to find water led to successful navigation strategies. The First Peoples of Australia soon passed along cultural knowledge to subsequent generations facilitating the peopling of the whole continent.

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An eye on the past: a view to the future

29 11 2021

originally published in Brave Minds, Flinders University’s research-news publication (text by David Sly)

Clues to understanding human interactions with global ecosystems already exist. The challenge is to read them more accurately so we can design the best path forward for a world beset by species extinctions and the repercussions of global warming.


This is the puzzle being solved by Professor Corey Bradshaw, head of the Global Ecology Lab at Flinders University. By developing complex computer modelling and steering a vast international cohort of collaborators, he is developing research that can influence environmental policy — from reconstructing the past to revealing insights of the future.

As an ecologist, he aims both to reconstruct and project how ecosystems adapt, how they are maintained, and how they change. Human intervention is pivotal to this understanding, so Professor Bradshaw casts his gaze back to when humans first entered a landscape – and this has helped construct an entirely fresh view of how Aboriginal people first came to Australia, up to 75,000 years ago.

Two recent papers he co-authored — ‘Stochastic models support rapid peopling of Late Pleistocene Sahul‘, published in Nature Communications, and ‘Landscape rules predict optimal super-highways for the first peopling of Sahul‘ published in Nature Human Behaviour — showed where, how and when Indigenous Australians first settled in Sahul, which is the combined mega-continent that joined Australia with New Guinea in the Pleistocene era, when sea levels were lower than today.

Professor Bradshaw and colleagues identified and tested more than 125 billion possible pathways using rigorous computational analysis in the largest movement-simulation project ever attempted, with the pathways compared to the oldest known archaeological sites as a means of distinguishing the most likely routes.

The study revealed that the first Indigenous people not only survived but thrived in harsh environments, providing further evidence of the capacity and resilience of the ancestors of Indigenous people, and suggests large, well-organised groups were able to navigate tough terrain.

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Mapping the ‘super-highways’ the First Australians used to cross the ancient land

4 05 2021

Author provided/The Conversation, Author provided


There are many hypotheses about where the Indigenous ancestors first settled in Australia tens of thousands of years ago, but evidence is scarce.

Few archaeological sites date to these early times. Sea levels were much lower and Australia was connected to New Guinea and Tasmania in a land known as Sahul that was 30% bigger than Australia is today.

Our latest research advances our knowledge about the most likely routes those early Australians travelled as they peopled this giant continent.


Read more: The First Australians grew to a population of millions, much more than previous estimates


We are beginning to get a picture not only of where those first people landed in Sahul, but how they moved throughout the continent.

Navigating the landscape

Modelling human movement requires understanding how people navigate new terrain. Computers facilitate building models, but they are still far from easy. We reasoned we needed four pieces of information: (1) topography; (2) the visibility of tall landscape features; (3) the presence of freshwater; and (4) demographics of the travellers.

We think people navigated in new territories — much as people do today — by focusing on prominent land features protruding above the relative flatness of the Australian continent. Read the rest of this entry »





Population of First Australians grew to millions, much more than previous estimates

30 04 2021

Shutterstock/Jason Benz Bennee


We know it is more than 60,000 years since the first people entered the continent of Sahul — the giant landmass that connected New Guinea, Australia and Tasmania when sea levels were lower than today.

But where the earliest people moved across the landscape, how fast they moved, and how many were involved, have been shrouded in mystery.

Our latest research, published today shows the establishment of populations in every part of this giant continent could have occurred in as little as 5,000 years. And the entire population of Sahul could have been as high as 6.4 million people.

This translates to more than 3 million people in the area that is now modern-day Australia, far more than any previous estimate.


Read more: We mapped the ‘super-highways’ the First Australians used to cross the ancient land


The first people could have entered through what is now western New Guinea or from the now-submerged Sahul Shelf off the modern-day Kimberley (or both).

But whichever the route, entire communities of people arrived, adapted to and established deep cultural connections with Country over 11 million square kilometres of land, from northwestern Sahul to Tasmania.

A map showing a much larger landmass as Australia is joined to both Tasmania and New Guinea due to lower sea levels

Map of what Australia looked like for most of the human history of the continent when sea levels were lower than today. Author provided


This equals a rate of population establishment of about 1km per year (based on a maximum straight-line distance of about 5,000km from the introduction point to the farthest point).

That’s doubly impressive when you consider the harshness of the Australian landscape in which people both survived and thrived.

Previous estimates of Indigenous population

Various attempts have been made to calculate the number of people living in Australia before European invasion. Estimates vary from 300,000 to more than 1,200,000 people. Read the rest of this entry »





Respecting Aboriginal culture through language

16 10 2019

(originally posted on the GE.blog)

GEL Logo KaurnaWhat’s in a name? Well, rather a lot, I think.

Names have meanings, and not just in the way that they tag people, places or objects. I am of the opinion that names go to the core of culture and personal identity in a way that our corporate/fast-food/market-driven society often fails to appreciate or espouse.

This is why we decided to seek cultural permission to have our lab’s name translated into the local Kaurna Language. Like many Aboriginal languages around Australia, Kaurna needs support, respect, and value among Aboriginal and non-Aboriginal people alike if it is to survive. And to me, the extinction of even one language is akin to the extinction of a species. Gone forever, never to be renewed.

But some people probably do not understand why this is important, which was brought home to me last night when a good friend asked why we decided to seek permission to have the lab’s name translated.

“Well,”, I said, “whenever I travel to other countries where multiple languages are spoken, be that in New Zealand1, South Africa2, Canada3, or southern Finland4, almost every official building, place, object, or document has a translation in different languages of the region.”

“Why don’t we seem to do that in Australia very much?”, I said.

After all, it is, at the very least, a sign of respect and recognition of the rightful custodians of the places and land; it recognises that there isn’t only one culture that usurps all others, and that there is multiple meaning and value in that place or object. Read the rest of this entry »





Academics and Indigenous groups unite to stand up for the natural world

26 04 2019

rainforest

Rain forest gives way to pastures in the Brazilian Amazon in Mato Grosso. Photo by Thiago Foresti.

More than 600 scientists from every country in the EU and 300 Brazilian Indigenous groups have come together for the first time. This is because we see a window of opportunity in the ongoing trade negotiations between the EU and Brazil. In a Letter published in Science today, we are asking the EU to stand up for Brazilian Indigenous rights and the natural world. Strong action from the EU is particularly important given Brazil’s recent attempts to dismantle environmental legislation and ‘develop the unproductive Amazon’.

It’s worth clarifying — this isn’t about the EU trying to control Brazil — it’s about making sure our imports aren’t driving violence and deforestation. Foreign white people trying to ‘protect nature’ abroad have a dark and shameful past, where actions done in the name of conservation have led to the eviction of millions of Indigenous people. This has predominantly been to create (what we in the world of conservation would call) ‘protected areas’. The harsh reality is that most protected areas either are or have been ancestral lands of Indigenous people who are closely linked to their land and depend on it for their survival. Clearly, conservationists need to support Indigenous people. This new partnership between European scientists and Brazilian Indigenous groups is doing just that.

Brazil

Brazil’s forest loss 2001-2013 shown in red. Indigenous lands outlined. By Mike Clark; data from GlobalForestWatch.org

In Brazil, many Indigenous groups still have a right to their land. This land is predominantly found in the Amazon rainforest, where close to a million Indigenous people live and depend on a healthy forest. Indigenous people are some of the best protectors of this vast forest, and are crucial to a future of long-term successful conservation. But Brazilian Indigenous groups and local communities are increasingly under attack. Violence on deforestation frontiers in Brazil has spiked this month, with at least 9 people found dead. The future is particularly scary for Indigenous people when there are quotes such as this from the man who is currently the President It’s a shame that the Brazilian cavalry hasn’t been as efficient as the Americans, who exterminated the Indians.

On top of human rights and environmental concerns, there is a strong profit driven case for halting deforestation. For example, ongoing deforestation in the Amazon risks flipping large parts of the rainforest to savanna – posing a serious risk to agricultural productivity, food security, local livelihoods, and the Brazilian economy. Zero-deforestation doesn’t harm agri-business, it allows for its longevity. Read the rest of this entry »





All (fisheries) models are wrong, but some are useful (to indigenous people)

1 08 2015

miracle_cartoonAnother post from Alejandro Frid. (Note: title modified from George Box‘s most excellent quote).

As an ecologist working for indigenous people of coastal British Columbia, western Canada, I live at the interface of two worlds. On the one hand, I know that computer models can be important management tools. On the other hand, my job constantly reminds me that whether a model actually improves fishery management depends, fundamentally, on the worldview that shapes the model’s objectives. To explore why, I will first review some general concepts about what models can and cannot do. After that, I will summarize a recent model of herring populations and then pull it all together in a way that matters to indigenous people who rely on marine resources for cultural integrity and food security.

Models do a great job of distilling the essence of how an ecosystem might respond to external forces—such as fisheries—but only under the specific conditions that the modeller assumes to be true in the ‘world’ of the model. Sometimes these assumptions are well-grounded in reality. Sometimes they are blatant but necessary simplifications. Otherwise, it would be difficult to ask questions about how major forces for which we have no historical precedent—such as the combined effects of industrial fisheries, ocean acidification and climate change—might be altering the ocean. For instance, due to our greenhouse gas emissions, the ocean is warming and contains less dissolved oxygen. These stressful conditions hamper the capacity of fish to grow, and appear to be on their way to shrinking the body sizes of entire fish communities1. If you want even to begin to comprehend what the ocean will look like in the long term due to these effects of climate change, it makes sense to assume, in the ‘world’ of your model, that fishing does not exist, even though you know it does. Of course, you would then acknowledge that climate change probably exacerbates the effects of fisheries, which highlights that you still have to examine the combination of these effects. And that is exactly what an excellent team of modellers did1. Read the rest of this entry »