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 »


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Categories : Australia, coasts, mathematics, modelling

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 »


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Categories : Australia, climate change, coasts, connectivity, demography, drought, ecology, Flinders University, modelling, population dynamics, statistics

Respecting Aboriginal culture through language

16 10 2019

(originally posted on the GE.blog)

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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 »


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Categories : Australia

The dingo is a true-blue, native Australian species

7 03 2019

dingo(reproduced from The Conversation)

Of all Australia’s wildlife, one stands out as having an identity crisis: the dingo. But our recent article in the journal Zootaxa argues that dingoes should be regarded as a bona fidespecies on multiple fronts.

This isn’t just an issue of semantics. How someone refers to dingoes may reflect their values and interests, as much as the science.

How scientists refer to dingoes in print reflects their background and place of employment, and the Western Australian government recently made a controversial attempt to classify the dingo as “non-native fauna”.

How we define species – called taxonomy – affects our attitudes, and long-term goals for their conservation.

What is a dog?

Over many years, dingoes have been called many scientific names: Canis lupus dingo (a subspecies of the wolf), Canis familiaris (a domestic dog), and Canis dingo (its own species within the genus Canis). But these names have been applied inconsistently in both academic literature and government policy.

This inconsistency partially reflects the global arguments regarding the naming of canids. For those who adhere to the traditional “biological” species concept (in which a “species” is a group of organisms that can interbreed), one might consider the dingo (and all other canids that can interbreed, like wolves, coyotes, and black-backed jackals) to be part of a single, highly variable and widely distributed species.

Members of the Canis genus: wolf (Canis lupus), coyote (Canis latrans), Ethiopian wolf (Canis simensis), black-backed jackal (Canis mesomelas), dingo (Canis dingo), and a representative of the domestic dog (Canis familiaris).

Read the rest of this entry »


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Categories : Australia, biodiversity, conservation, conservation biology, conservation ecology, dingo, ecosystem function, endemism, exploitation, fox, harvest, human-wildlife conflict, kangaroo, livestock, mammal, management, meso-predator release, predation, predator

No evidence climate change is to blame for Australian megafauna extinctions

29 01 2016

bw spear throwingLast July I wrote about a Science paper of ours demonstrating that there was a climate-change signal in the overall extinction pattern of megafauna across the Northern Hemisphere between about 50,000 and 10,000 years ago. In that case, it didn’t have anything to do with ice ages (sorry, Blue Sky Studios); rather, it was abrupt warming periods that exacerbated the extinction pulse instigated by human hunting.

Contrary to some appallingly researched media reports, we never claimed that these extinctions arose only from warming, because the evidence is more than clear that humans were the dominant drivers across North America, Europe and northern Asia; we simply demonstrated that warming periods had a role to play too.

A cursory glance at the title of this post without appreciating the complexity of how extinctions happen might lead you to think that we’re all over the shop with the role of climate change. Nothing could be farther from the truth.

Instead, we report what the evidence actually says, instead of making up stories to suit our preconceptions.

So it is with great pleasure that I report our new paper just out in Nature Communications, led by my affable French postdoc, Dr Frédérik Saltré: Climate change not to blame for late Quaternary megafauna extinctions in Australia.

Of course, it was a huge collaborative effort by a crack team of ecologists, palaeontologists, geochronologists, paleo-climatologists, archaeologists and geneticists. Only by combining the efforts of this diverse and transdisciplinary team could we have hoped to achieve what we did. Read the rest of this entry »


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Categories : Australia, climate change, conservation, exploitation, extinction, harvest, modelling, science, synergies

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).

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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 »


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Categories : conservation

It couldn’t have been us!

29 05 2012

A few months ago I asked Chris Johnson of the University of Tasmania to put together a post on his recent Science paper regarding Australian megafaunal extinctions. It seems that it stirred, yet again, some controversy among those who refuse to accept (mainly archaeologists) that humans could have had anything to do with pre-European extinctions. Indeed, how could humans possibly have anything to do with extinctions?!

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Like Corey, I am mainly interested in current environmental problems. But now and then I wade into the debate over the extinction of Australia’s Pleistocene megafauna [editor’s note: Chris literally wrote the book on Australian mammal extinctions over the last 50,000 years], those huge animals that wandered over the Australian landscape until about 40,000 years ago.

This is an endlessly fascinating topic. The creatures were wonderful and bizarre – it’s great fun doing work that lets you think about marsupial lions, giant kangaroos, geese bigger than emus, echidnas the size of wombats, and the rest. The cause of their extinction is perhaps the biggest mystery, and the most vexed controversy, in the environmental history of Australia. And for reasons that I will explain in a minute, solving this mystery is profoundly important for our understanding of contemporary Australian ecology.

The latest bit of work on this is a paper that a group of us (including Corey’s close colleague, Barry Brook) published in Science. You can see it here (if you don’t have access to Science, email me for a copy). So far, research on this problem has concentrated on dating fossils to find out when megafauna species went extinct. Several recent studies have found evidence for extinction between 40,000 and 50,000 years ago, which is about when people first came to Australia. But the conclusion that people caused a mass extinction of megafauna has been strenuously criticised, because so far it is based on only a few species with good collections of dates. The critics argue that other species disappeared before humans arrived, maybe in an extended series of extinctions caused by something else, like a deteriorating climate.

This argument over fossils will be with us for a long time. Because finding and dating fossils is such hard, slow work, the fossil record will inevitably give a seriously incomplete picture of what happened. One way around this problem would be to analyse the fossil record using mathematical approaches that take into account the problem of incomplete sampling. Corey is lead author of a recent paper that introduced a great new set of tools for this, and we are part of a group that is currently assembling a complete database of all recent dates on Australian fossils so that we can analyse them using these tools. Stay tuned for the result. Read the rest of this entry »


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Categories : Australia, bushmeat, climate change, conservation, decline, ecosystem function, exploitation, extinction, fire, harvest, invasive species, mammal


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