Small skulls point to human migration highway to Australia

By: Thomas Schmitt Attorney on August 26, 2019 / comment : 0 Anthropology, Australasia, Australia, Java, Papua New Guinea, South East Asia

Human remains discovered on Alor island in Indonesia offer new insight into human migration through Southeast Asia thousands of years ago, say researchers from The Australian National University (ANU).

Credit: Samper Carro et al. 2019

Lead researcher Dr. Sofía Samper Carro says the two skulls, dated between 12,000 and 17,000 years old, are the oldest human remains ever found in Wallacea—the islands between Java, Papua New Guinea and Australia.

"Although we were aware that modern humans were in Timor and Sulawesi over 40,000 years ago, these remains are the first fossil evidence of modern human presence in Wallacea," Dr. Samper Carro said. "The area around Alor may have been a sort of 'highway', with people moving through these islands, and finally getting to Australia."

That wasn't the only exciting find.

"What is really interesting is the small size of their heads," Dr. Samper Carro said. "The size seems to be similar to other remains found later in this region, dated to between 7,000—10,000 years old. This is potentially the result of a reduction in size after the first modern humans settled in these islands. This is different to what you find in Australia and other parts of mainland Southeast Asia during the same period, where, in general, humans have larger skulls."

Dr. Samper Carro says one possible explanation for this is the so-called "island effect"—the idea that when humans and other large mammals get to an island where there are not enough food resources and predators, they tend to get smaller, while small mammals will get bigger.

"It's been suggested this is what may've happened to Homo floresiensis (hobbit) and, potentially, it may have also affected the recently discovered Homo luzonensis," Dr. Samper Carro said.

A huge number of fish bones have also been found in the Tron Bon Lei site in Alor, which could offer some important clues.

"The question is, was that enough food for them?" Dr. Samper Carro said. "The archaeological site show gaps which may indicate that, at some point, humans moved from the island, or they weren't using this particular site and they went somewhere else. This could be because of environmental changes, or because they didn't have enough food to survive. More excavations and research in Alor will help us to test these theories."

Dr. Samper Carro says these findings could build on long-held ideas about human migration.

"It's a really exciting time. Human evolution studies have been focused in Africa and Europe for a long time, but now more and more we seem to be getting new findings from Asia that are challenging our previous conceptions. There's been evidence found that Homo sapiens were around in North Africa and the Mediterranean earlier than we thought, coinciding with the presence of different hominins in other parts of the world. Human evolution is getting more exciting and complex."

One of the skulls discovered on Alor was found with fish hooks and ornaments. Dr. Samper Carro says burial traditions are also a good example of the mobility of humans and ideas. "New people come with new traditions, just like we see now," she said. "If you move somewhere, you bring your culture and traditions with you, and the next generation will continue some of those traditions. We can see that reflected in the way these people buried their loved ones."

The research has been published in the Journal of Human Evolution.

Source: Australian National University [August 26, 2019]

First Australians may have arrived in large groups using complex technologies

By: Thomas Schmitt Attorney on June 20, 2019 / comment : 0 Anthropology, Australasia, Australia, Early Humans, Indigenous Cultures, Papua New Guinea

New insights into how people first arrived in Australia have been revealed by a group of experts brought together to investigate the continent's deep history.

The emergent picture of regional Pleistocene complexity from genomes, fossils and material culture [Credit: Corey J. A. Bradshaw et al. 2019]

They used sophisticated modelling to determine not only the likely routes travelled by Aboriginal people tens of thousands of years ago, but also the sizes of groups required for the population to survive in harsh conditions.

The research, published today in two companion papers (one in Scientific Reports and the other in Nature Ecology and Evolution), confirms the theory that people arrived in several large and deliberate migrations by island-hopping to reach New Guinea more than 50,000 years ago.

While many Aboriginal cultures believe people have always been here, others have strong oral histories of ancestral beings arriving from the north.

"We know that Aboriginal people have lived here for more than 50,000 years. This research offers a greater understanding of how migration events took place and further evidence of the marine and navigation capabilities used to make these deliberate journeys," said Professor Michael Bird, from the Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage (CABAH) and James Cook University.

The team of multidisciplinary researchers from CABAH and the CSRIO set out to establish the most likely route travelled to reach the ancient mega-continent, known as Sahul (New Guinea, Australia and Tasmania joined at times of low sea level).

Arrival of First Australians infographic [Credit: Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage (CABAH)]

"We developed demographic models to determine which island-hopping route ancient people most likely took," said CABAH's Professor Corey Bradshaw, from Flinders University.

"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. 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."

The researchers also used complex mathematical modelling -- considering factors including fertility, longevity, past climate conditions, and other ecological principles -- to calculate the numbers of people required for the population as a whole to survive.

The simulations indicate that at least 1300 people arrived in either a single migration event or smaller, successive waves averaging at least 130 people every 70 years or so, over the course of about 700 years.

"This suggests planned and well-organised maritime migration, rather than accidental arrival" Professor Bradshaw added.


The studies confirm the ancestors of Aboriginal and Torres Strait Islander people possessed sophisticated technology and knowledge to build watercraft. This research also showcases the remarkable ability at that time to plan, navigate, and make multiple complicated, open-ocean voyages to directly transport large numbers of people.

"Both studies are unique because they relied on past environmental information and did not use any genetic data. We are very excited to see how further archaeological and genetics studies in CABAH can contribute to this story," says Dr Laura Weyrich, a CABAH investigator at the University of Adelaide.

The papers Early human settlement of Sahul was not an accident and Minimum founding populations for the first peopling of Sahul, were co-authored by scientists from around Australia, including Flinders University, James Cook University, University of Wollongong, University of New South Wales, University of Adelaide, Australian National University, and the CSIRO.

CABAH brings together expertise from diverse academic disciplines to answer fundamental questions about the natural and human history of our region, including how and when people first came to Australia.

Source: Flinders University [June 20, 2019]

An island haven for frogs in a sea of extinctions

By: Thomas Schmitt Attorney on June 03, 2019 / comment : 0 Ecosystems, Endangered Species, Natural Heritage, Papua New Guinea, Wildlife

New Guinea is one of the only places in the world where frogs are safe from the species-destroying chytrid fungus. An international team of scientists has published a new paper that shows how to keep it that way, but they need help to carry out their plan.

The New Guinean frog Sphenophryne cornuta carrying its young on its back [Credit: Stephen J Richards]

The chytrid fungus has wiped out more than 90 frog species around the world, and it's driving hundreds more towards extinction. New Guinea—the world's largest tropical island, and home to 6% of all known frog species—is one of the last remaining refuges from the deadly infection.

A team of scientists led by researchers from Macquarie University and the University of New England in Australia think they know how to keep the island's frogs safe, but they need support to establish a long-term program of monitoring and conservation.

Writing in the journal Frontiers in Ecology and the Environment, the group of 30 experts from Australia, the USA, China, Indonesia and Papua New Guinea calls for urgent action.

"You don't often spot a conservation disaster before it happens and get the chance to stop it," says Deborah Bower of the University of New England in Armidale, Australia, who is the first author of the article. "We know what needs to be done."

The infectious chytrid fungus has been described as the most destructive pathogen known to science. It has destroyed more than 90 species of frog entirely and caused declines in almost 500 more.

The New Guinean frog Lechriodus aganoposis is one of up to a hundred species that would be at risk if the chytrid fungus reaches the tropical island [Credit: Stephen J. Richards]

The international pet trade helped the chytrid fungus spread rapidly from its origins in East Asia over recent decades, and it now infects frogs on every continent. It is one of the key reasons why 40% of the world's frog species now face the threat of extinction.

New Guinea's tropical climate and hundreds of native frog species make it an ideal environment for chytrid. But field tests have so far found no traces of the killer fungus.

"A lot of New Guinea's frogs are closely related to Australian species that have been devastated by chytrid, so we expect they would be just as vulnerable," says Simon Clulow at Macquarie University in Sydney, Australia, who leads the research team.

"Other New Guinea frog species are unusual because they hatch from eggs as fully formed frogs, rather than going through a tadpole stage, and we don't know how chytrid will affect them."

The team estimates that around 100 species of frog would be in danger if chytrid reaches New Guinea, and their decline could have huge impacts across the ecosystem as they are predators of insects and other small creatures but also prey for larger animals.

The frog Oreophryne oviprotector is one of around a hundred species that could be at risk if chytrid fungus reaches the tropical island of New Guinea [Credit: Stephen J. Richards]

The research team includes international experts in frog conservation—including Lee Berger, the Australian who first discovered the chytrid fungus and showed it was responsible for frog species declines and extinctions—alongside local researchers with deep knowledge of the environment of New Guinea.

They have been studying frogs in New Guinea since 2015, and have already started working with zoos, universities and the Papua New Guinea government to build a program to keep captive frogs and store their sperm and eggs to preserve genetic diversity.

The team has developed a 5-step program of preparation, prevention, detection, response and recovery to keep the deadly fungus off New Guinea and to minimise the impact if it does arrive.

As well as preserving New Guinea's frogs, the program would build local capacity in science, and disease surveillance and diagnosis that will have applications for animal and public health.

Source: Macquarie University [June 03, 2019]

Precursors of a catastrophic collapse

By: Thomas Schmitt Attorney on May 16, 2019 / comment : 0 Earth Science, Geology, Palaeontology, Papua New Guinea

On the morning of the 13th of March 1888, the inhabitants of the Finschhafen trading post on the east coast of New Guinea were awakened by a dull rumbling sound. An eyewitness later reported that the water in the port had receded at the same time. A short time later, several two- to three-metre high waves hit the coast. It was a tsunami on that fateful morning that devastated the surrounding coasts. Several thousand people probably died in New Guinea and the Bismarck Archipelago.

The research vessel SONNE in front of Ritter Island during the expedition SO252 in autumn 2016 [Credit: Christian Berndt/GEOMAR]

The cause of the tsunami was quickly discovered: the largest part of the volcanic island of Ritter Island, 150 kilometres from Finschhafen, had slipped into the sea in a single catastrophic collapse. However, some questions about the exact course of the landslide remained unanswered.

In the international journal Earth and Planetary Science Letters, researchers from the GEOMAR Helmholtz Centre for Ocean Research Kiel together with colleagues from the University of Birmingham, the University of Malta, the University of London and the German Research Centre for Geosciences, have now published a study showing that the volcanic slope of Ritter Island had already slipped before the catastrophe of 13 March 1888 - but much more slowly. "These new findings help us to better assess the hazard potential of other volcanic islands," says Dr Jens Karstens of GEOMAR, first author of the study.

The study is based on the expedition SO252 of the German research vessel SONNE to Ritter Island in Autumn 2016. With seismic methods, the international team led by Prof. Dr. Christian Berndt (GEOMAR) precisely measured the traces of the disaster of 1888. They found evidence that the flank of the island had moved sporadically over a long period of time before 1888. This is indicated by corresponding deformation of the subsurface at a smaller volcanic cone off the coast of Ritter Island.

3D visualization of Ritter Island and the surrounding seafloor with traces of the landslide of 1888 [Credit: Jens Karstens/GEOMAR]

It is unknown whether slow landslides at volcanic flanks are precursors of a catastrophic collapse, or even whether they might reduce the risk of such a collapse because they relieve tension from the volcanic system. "At Ritter Island, we now have evidence that sporadic, small landslides have preceded a much larger one," explains Dr Karstens.

Both types of landslides were observed last year on active volcanoes. Last year's eruption of Kilauea on Hawaii was accompanied by a landslide of the volcano flank, which caused a moderate earthquake. The eastern flank of Mount Etna in Sicily is also moving slowly towards the sea, as showed in a study published in Autumn 2018.

In December 2018, an eruption of the volcano Anak Krakatau caused a landslide that triggered a tsunami in the Sunda Strait (Indonesia) and killed more than 400 people. The events at Anak Krakatau are comparable to those that took place on the 13th of March 1888 at the Ritter Island Volcano. This demonstrates the relevance of the findings at Ritter Island for hazard assessments on volcanic islands all over the world.


"The better we know the dynamics of such events, the better we can asses the hazard for a given region. Ritter Island is a very good case study because the volcano resembles many other volcanic islands and because the eruption and the tsunami are well documented thanks to eyewitness accounts. Together with our modern research methods, we can get a more complete picture of the processes of 1888," summarizes Dr. Karstens.

Source: Helmholtz Centre for Ocean Research Kiel (GEOMAR) [May 16, 2019]

Multiple Denisovan-related ancestries in Papuans

By: Thomas Schmitt Attorney on April 11, 2019 / comment : 0 Anthropology, Early Humans, Genetics, Human Evolution, Indigenous Cultures, Papua New Guinea

As they dispersed out of Africa anatomically modern humans interbred with their close relatives, the Neanderthals and Denisovans. An international research team examined DNA fragments passed down from these ancient hominins to modern people living in Island Southeast Asia and New Guinea. Their study suggests that the ancestry of Papuans includes not just one but two distinct Denisovan lineages, which had been separated from each other for hundreds of thousands of years. In fact, one of those Denisovan lineages is so different from the other that they might even be considered an entirely new group of archaic hominins.

Image from the film 'Forgotten Bird of Paradise' by Dominic Brown [Credit: The Ecologist]

The findings are based on a new study led by Murray Cox from Massey University in New Zealand and made possible by sampling efforts led by Herawati Sudoyo from the Eijkman Institute for Molecular Biology in Jakarta, Indonesia. The data were collected and analyzed by an international team of researchers, including Mark Stoneking from the Max Planck Institute for Evolutionary Anthropology.

Taken together with previous work - which has pointed to a third Denisovan lineage in the genomes of modern Siberians, Native Americans, and East Asians - the evidence "suggests that modern humans interbred with multiple Denisovan populations, which were geographically isolated from each other over deep evolutionary time," the researchers write.

The new evidence also unexpectedly shows extra mixing between Papuans and one of the two Denisovan groups, suggesting that this group actually lived in New Guinea or its adjacent islands. Moreover, Denisovans may have lived in the area until as recently as 30,000 years ago, making them one of the last surviving groups of archaic hominins.

"People used to think that Denisovans lived on the Asian mainland and far to the north," says Cox. "Our work instead shows that the center of archaic diversity was not in Europe or the frozen north, but instead in tropical Asia." Stoneking adds, "Moreover, this archaic diversity seems to have persisted much longer in Island Southeast Asia and New Guinea than elsewhere in the world."

It had already been clear that Island Southeast Asia and New Guinea was a special place, with individuals there carrying more archaic hominin DNA than anywhere else on Earth. The region was also recognized as key to the early evolution of Homo sapiens outside Africa. But there were gaps in the story.

To help fill those gaps, the team identified stretches of archaic DNA from 161 new genomes spanning 14 island groups in Island Southeast Asia and New Guinea. Their analyses uncovered large stretches of DNA that did not jibe with a single introgression of genes from Denisovans into humans in the region. Instead, they report, modern Papuans carry hundreds of gene variants from two deeply divergent Denisovan lineages. In fact, they estimate that those two groups of Denisovans had been separated from one another for 350,000 years.

The new findings highlight how "incredibly understudied" this part of the world has been, the researchers say. To put it in context, many of the study's participants live in Indonesia, a country the size of Europe that is the 4th largest country in the world based on population size. And yet, apart from a handful of genome sequences reported in a global survey of genomic diversity in 2016, the new paper reports the first Indonesian genome sequences. There also has been a strong bias in studies of archaic hominins toward Europe and northern Eurasia, because DNA collected from ancient bones survives best in the cold north.

This lack of global representation in both ancient and modern genome data is well noted, the researchers say. "However, we don't think that people have really grasped just how much of a bias this puts on scientific interpretations - such as, here, the geographical distribution of archaic hominin populations," Cox says.

As fascinating as these new findings are, the researchers say their primary aim is to use this new genomic data to help improve healthcare for people in Island Southeast Asia. They say this first genome survey in the region now offers the baseline information needed to set that work in motion.

The findings are published in the journal Cell.

Source: Max Planck Institute for Evolutionary Anthropology [April 11, 2019]

The secret behind coral reef diversity? Time, lots of time

By: Thomas Schmitt Attorney on November 09, 2018 / comment : 0 Biodiversity, Ecosystems, Indonesia, Natural Heritage, Oceans, Papua New Guinea, Philippines, Wildlife

Strap on a diving mask and fins and slip under the crystal-clear water near a coral reef in Indonesia, Papua-New Guinea or the Philippines, and you'll immediately see why divers and snorkelers from across the world flock to the area. Known as the Coral Triangle, the region is famous for its unmatched diversity of reef fish and other marine creatures.

Until now, researchers had a hard time explaining why the Coral Triangle in the Central-Indo Pacific  is the world's leading spot of marine biodiversity [Credit: GreensMPs/Flickr]

Fish of all shapes and colors dart in and out of crevices created by the dazzling shapes of corals, colorful sponges and other reef-building organisms. With a little luck, a diver might catch a glimpse of a shark patrolling the reef or a turtle soaring across the landscape of colors.

While underwater enthusiasts have long known and cherished the biodiversity in the Central-Indo Pacific Ocean, scientists have struggled for more than half a century to explain what exactly makes the region the world's No. 1 hot spot of marine biodiversity and sets it apart from other marine regions around the world.

Several hypotheses have been put forth to explain the Central-Indo Pacific region's extraordinary diversity. Some researchers suggested species emerge at a faster rate there compared to other parts of the world's oceans, while others attributed it to the region's central location between several species-rich swaths of ocean in the broader Indo-West Pacific. Still others pointed to the region's low extinction rates.

Now, a study led by University of Arizona doctoral student Elizabeth Miller has revealed that Indo-Pacific coral reefs have accumulated their unrivaled richness of fish species not because of some unknown, elusive quality, but simply because they had the time.

"People used to think that new species evolve more quickly in tropical marine areas, so you get the high diversity we see today very quickly," Miller said. "Instead, we found that diversity in the Central-Indo Pacific has slowly built over a long time."

The study, published in the journal Proceedings of the Royal Society of London, is the first to show a direct link between time and species richness, according to Miller.

Until now, Miller explained, it was widely believed that tropical coral reefs, similar to tropical rain forests, are hot spots of biodiversity because of an intrinsic propensity to diversify into more species than other regions. Her research showed that wasn't the case.

A clownfish seeks shelter in its sea anemone home in the Great Barrier Reef, which is part of this study  [Credit: Deborah Shelton]

The team discovered that speciation rates are actually higher in cold marine areas such as the Arctic and Antarctic. However, while changes in biodiversity in the Central-Indo Pacific region could be compared to a slow but long-burning flame, in colder ocean regions, they are more like fireworks.

"There, species evolve relatively quickly, but each glaciation period clears out much of what was there before," Miller said. "Once the glaciers recede, they leave empty niches waiting to be repopulated by new species."

Frequent environmental upheaval results in overall biodiversity being lower in colder ocean regions.

In the Coral Triangle, on the other hand, new species have evolved less rapidly, but because conditions have been much more stable over long periods of geological time, they were more likely to stick around once they appeared and slowly accumulate to the biological diversity we see today.

"This suggests that a region may need long-term stability to accumulate high species diversity," Miller said. "According to our study, the magic number appears to be 30 million years."

In the Central-Indo Pacific, plate tectonics created a wide platform of shallow ocean, while its central location made it a target for colonization. It was the right place at the right time for the fishes that colonized the region.

"Things haven't changed much there in the past 30 to 35 million years," Miller said. "In contrast, other marine regions, such as the Caribbean, underwent periods of instability and isolation, and therefore fewer colonizations and higher rates extinction of the lineages that were there previously - all those factors add up to less evolutionary time."

For the study, Miller and her team used distribution data of almost all spiny ray-finned fishes - 17,453 species in total, representing about 72 percent of all marine fishes and about 33 percent of all freshwater fishes. They used several different statistical methods to reconstruct the causes of underlying species richness patterns among global marine regions.

To disentangle how marine fish diversity unfolded over time, the team then used a published evolutionary tree of this fish group and performed biogeographic reconstructions.

"Biogeographic reconstructions help us understand where ancestors were living at various places back in time, based on where species live today and how they are related," Miller said. "It's easy if you only compare two species that live in the same place, but if you have thousands of species and go back further and further in time, more ancestors come into play and things become more difficult."

Evolutionary biologists rely on sophisticated computer algorithms to manage and interpret the extremely large data sets. The method used by Miller and her team created many hypothetical scenarios of where species evolved. The researchers then used these scenarios to test how different models explain today's biodiversity.

"It's like drawing family histories, each slightly different," Miller said. "You start out with analyses and repeat them hundreds of times, each time based on some possible history to try and encompass uncertainty to see how they play out. In our study, it turned out the uncertainty is low, which is reassuring. It means it's a really robust result."

The general idea that patterns of diversity can be explained by how long a group has been present rather than how quickly they proliferate is relevant to lots of different systems, according to the researchers. For example, biologists have observed that the timing of colonization explains the high diversity of certain animal groups in terrestrial ecosystems, such as treefrogs in the Amazon rainforests, salamanders in the Appalachian Mountains and lizards in the desert Southwest.

"The general takeaway is that these patterns of high diversity may take tens of millions of years to arise, but can be wiped out in a few years by human impacts," said John Wiens, senior author of the paper and a professor in the UA Department of Ecology and Evolutionary Biology. "Unfortunately, the high diversity of reef fish in the Coral Triangle may soon disappear because of the impacts of human-induced climate change on coral reefs. The diversity that gets lost in the next few years may take tens of millions of years to get back."

Source: University of Arizona [November 09, 2018]

Megalithic statues discovered in Srobu site, Papua

By: Thomas Schmitt Attorney on November 01, 2018 / comment : 0 Archaeology, Asia, Indonesia, Papua New Guinea, South East Asia

An archaeologist from Papua Archaeological Center, Erlin Novita Idje Djami, together with her team, has found two megalithic statues of Polynesian style on the Mount Srobu site located in Abepantai Village, Abepura District, Jayapura City, Papua Province.

Credit: Satusuaraexpress

"In 2018, we have made a spectacular discovery, namely two megalithic statues of Polynesian style. But, I prefer to call them the megalithic statues of Srobu Papua," she stated here on Wednesday.

She added that the discovery was extraordinary and unique because the statues were different from those found in other areas in Papua.

The two statues are one metre high and weigh around 50 to 60 kilograms.

"The two statues and other cultural materials are being analyzed at the Papua Archaeological Center," Djami noted.

She revealed that the Srobu Mountain Site is one of the important archaeological sites in Jayapura city. This site is located on a cape in Youtefa Gulf. This area is a place for some locals to look for shells as raw material to make lime that is used for chewing betel.

"In February 2014, we got information that there were bones found in Srobu Mountain. The locals guessed the bones were those of Japanese soldiers," she remarked, adding that the Papua Archaeology Centre, together with the Provincial Culture and Tourism Office, later went to the location to check the information.

"Surprisingly, we not only found bones but also various cultural objects, such as pottery fragments, stone tools, and mollusks shells. I can say that this is one of the great archaeological sites in Papua," Djami revealed.

After that, the Papua Archaeology Centre set up a plan to conduct the first research in 2014.

"That year, we carried out a surface survey but did not cover all areas. We also carried out excavations and found a number of stone axe artefacts, oval axes, and tools made of shells, beside pottery with beautiful decoration, "he added.

According to E Djami , the findings of cultural objects characterize a culture from prehistoric times.

"From the dating, the Mount Srobu site has been inhabited since 3,780 before present or BP. This means the site is from Neolithic era, showing that Papua already has an extraordinary culture," she noted.

In addition to Neolithic culture, in 2015, the researchers also found megalithic relics, in the form of menhirs and dolmens, which were neatly arranged on the ground.

"We will continue this research until this year. So, every year, our research on the Srobu Site discovers unique new things that illustrate a cultural revolution at that location," she explained.

He hoped that the Srobu Site could become one of the historical tourist destinations in Jayapura City in particular, and Papua, in general.

"This Srobu Site is an open prehistoric settlement. Neolithic settlements in Indonesia are very few, but in Papua, the findings of this culture are extraordinary," she elaborated, adding that Srobu Site is more unique than all the Neolithic or prehistoric settlement sites in Papua.

Source: AntaraNews [November 01, 2018]

Study finds most likely route of first humans into Australia

By: Thomas Schmitt Attorney on October 31, 2018 / comment : 0 Anthropology, Australasia, Genetics, Indonesia, Papua New Guinea

A new study from ANU indicates the most likely route the ancestors of Aboriginal people took to enter Australia for the first time tens of thousands of years ago.

Gwion Gwion rock art site, Kimberley, WA [Credit: Peter Eve]

Co-lead researcher Shimona Kealy said these people probably travelled through Indonesia's northern islands, into New Guinea and then Australia, which were part of a single continent between 50,000 and 70,000 years ago, when sea levels were 25-50 metres below the current level.

"We've created a treasure map of sorts with the likely route across land and water that these incredible people took to reach Australia," said Ms Kealy, a Ph.D. scholar at the School of Culture, History and Language and an Associate Investigator at the ARC Centre of Excellence for Australian Biodiversity and Heritage at ANU.

"We've circled all of the islands that we want to explore further to find archaeological evidence to test if this is in fact the path that they took.

"Archaeologists have yet to explore most of Indonesia's northern islands for human settlements predating the oldest sites found in Australia. These islands could hold the key to the mystery of how the first humans made it to Australia's shores."

The findings challenge a popular theory that these early adventurers travelled from Southeast Asia, through Indonesia and Timor and then across sea to reach Australia's shores and land that is part of the Northern Territory today.

Map of island Southeast Asia showing possible routes to Australia [Credit: Shimona Kealy et al. 2018]

The study modelled the least-cost path from Southeast Asia to Australia, by considering factors such as difficulty to travel up slopes, visibility at sea, access to fresh water along the many potential pathways and the sophistication of maritime technology at the time.

Ms Kealy said the oldest dates for human occupation on the Australian-New Guinea continent (known as Sahul) represented the earliest, indirect evidence for sea faring by humans anywhere in the world.

"This study helps to tell the Australian story, particularly for Indigenous people, and acknowledges the bravery, innovation and maritime technologies and skills of these early modern humans," Ms Kealy said.

The islands directly north and west of Sahul (known as Wallacea) were never connected to the mainland, requiring multiple successful water crossings east from mainland Southeast Asia (Sunda).


"These people hopped their way along these islands, probably looking for a place to live where they would have access to reliable food staples and other resources—the visibility between islands would have been very favourable in terms of enabling this adventurous spirit," Ms Kealy said.

Co-lead researcher Professor Sue O'Connor from ANU said the proposed alternative route through Timor onto the northwest coast of Australia is now seen as less likely as a result of this study's least-cost pathway modelling.

"The suggested route through Timor is also considered less likely given comprehensive archaeological evidence indicates the earliest human settlements in Timor are much younger than those found in Madjedbebe in Arnhem Land in the Northern Territory," said Professor O'Connor, a researcher at the School of Culture, History and Language and a Chief Investigator at the ARC Centre of Excellence for Australian Biodiversity and Heritage at ANU.

The study is published in the Journal of Human Evolution.

Source: Australian National University [October 31, 2018]