People first arrived in Australia in large groups

People first arrived in Australia in large groups 50,000 years ago, computer modelling reveals

The ancestors of the aboriginal peoples of Australia and the Torres Strait Islands arrived in the country one or more large groups, totalling at least 1,300 people.

Experts used complex models to determine which island-hopping routes the original migrants must have taken to reach Australia, coming up with two possibilities.

The most likely involved an island-hoping route, arriving first in West Papua New Guinea around 50,000 years ago.

The researchers also calculated the minimum number of people that must have arrived to enable the burgeoning population to survive.

These travellers may either have arrived in one single migration event, or alternatively in a series of pulses over a space of around 700 years.

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The ancestors of the aboriginal peoples of Australia (pictured) and the Torres Strait Islands arrived in the country one or more large groups, totalling at least 1,300 people

Although many Aboriginal cultures believe that they originate in Australia, some have strong oral histories of their distant ancestors having arrived from the north.

‘We know that Aboriginal people have lived here [in Australia] for more than 50,000 years,’ said earth scientist Michael Bird of the James Cook University, in Queensland.

Professor Bird and his colleagues from the Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage (CABAH) and the national science agency (CSIRO) investigated how the aboriginal people first came to Australia.

‘We developed demographic models to determine which island-hopping route ancient people most likely took,’ said ecologist Corey Bradshaw of CABAH and Flinders University in Adelaide.

‘A northern route connecting the islands of Mangoli, Buru, and Seram into West Papua New Guinea would probably have been easiest to navigate and survive,’ he added.

‘This route was easiest when compared to the southern route from Timor that leads to the now-drowned Sahul Shelf in the modern-day Kimberley region.’

At this time, lower sea levels would have joined Australia, New Guinea and Tasmania in an ancient mega-continent that experts have dubbed Sahul.

Using complex mathematical models, researchers also calculated the minimum number of ancient people that would have needed to migrate to Australia in order to ensure that the population could survive in the long run.

They considered various factors, including the people’s fertility and longevity, as well as the past climate conditions and other ecological principles.

The team found that at least 1,300 people would have been needed to form the founding population.

These may either have arrived in a single migration event, or through successive waves averaging around at least 130 people every 70 years across the course of around 700 years. 

‘This suggests planned and well-organised maritime migration, rather than accidental arrival,’ said Professor Bradshaw. 

The findings confirm not only that the ancestors of the aborigines and Torres Strait islanders must have had sophisticated enough technology to both built watercraft and plan, navigate and execute open-ocean voyages for large numbers of people.

‘Both studies are unique because they relied on past environmental information and did not use any genetic data,’ said biologist Laura Weyrich, who is a CABAH investigator at the University of Adelaide.

‘We are very excited to see how further archaeological and genetics studies in CABAH can contribute to this story.’

The full findings of the study were published in the journals Nature Ecology & Evolution and Scientific Reports.

WHAT DO WE KNOW ABOUT HUMANKIND’S JOURNEY OUT OF AFRICA?

The traditional view

The traditional ‘Out of Africa’ model suggests that modern humans evolved in Africa and then left in a single wave around 60,000 years ago. 

The model often holds once modern humans left the continent, a brief period of interbreeding with Neanderthals occurred.

This explains why individuals of European and Asian heritage today still have ancient human DNA.

There are many theories as to what drove the downfall of the Neanderthals.

Experts have suggested that early humans may have carried tropical diseases with them from Africa that wiped out their ape-like cousins.

Others claim that plummeting temperatures due to climate change wiped out the Neanderthals.

The predominant theory is that early humans killed off the Neanderthal through competition for food and habitat.

How the story is changing in light of new research

Recent findings suggest that the ‘Out of Africa’ theory does not tell the full story of our ancestors.

Instead, multiple, smaller movements of humans out of Africa beginning 120,000 years ago were then followed by a major migration 60,000 years ago.

Most of our DNA is made up of this latter group, but the earlier migrations, also known as ‘dispersals’, are still evident.

This explains recent studies of early human remains which have been found in the far reaches of Asia dating back further than 60,000 years.

For example, H. sapiens remains have been found at multiple sites in southern and central China that have been dated to between 70,000 and 120,000 years ago.

Other recent finds show that modern humans reached Southeast Asia and Australia prior to 60,000 years ago.

Based on these studies, humans could not have come in a single wave from Africa around this time, studies have found. 

Instead, the origin of man suggests that modern humans developed in multiple regions around the world.

The theory claims that groups of a pre-human ancestors made their way out of Africa and spread across parts of Europe and the Middle East.

From here the species developed into modern humans in several places at once. 

The argument is by a new analysis of a 260,000-year-old skull found in Dali County in China’s Shaanxi Province.

The skull suggests that early humans migrated to Asia, where they evolved modern human traits and then moved back to Africa. 

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