The Aboriginal peopling of New England. Reoccupation following the ending of the Last Glacial Maximum

Stuart’s Point today, the site of the oldest known Aboriginal occupation in New England following the end of the Last Glacial Maximum This is the sixth and final in a series on the Aboriginal peopling of New England drawn from the introductory course I have been running on New England's history. I will continue the story of the Holocene period in a later series.   

In my last column I discussed the likely impact of the Last Glacial Maximum (LGM), a cold dry windy period running from around 12,000 to 15,000 years ago, on New England’s Aboriginal peoples.

Faced with persistent drought and temperatures up to 8C below present, New England’s Aboriginal peoples were forced to retreat to refuge areas where food as well as protection from the elements was still available. Whole groups may have been wiped out.

Around 15,000 years ago, the LGM began to ease. From around 12,000 years ago, the period now described as the Holocene began. Average temperatures rose, rainfall increased. Deserts retreated westwards, while plants, animals and humans began to reoccupy the landscape.

This process took time, while its effects varied from place to place.

Down on our coastal strip, sea levels rose by 130 metres rushing inland past the coastline we know today. If you were standing where Kempsey is now, you would be on the coast. Shelters, camping grounds, ceremonial sites and food resources were submerged by the rising waters.

Slowly, the silt laden rivers swollen by higher Tablelands’ rainfall pushed back, joined by sea currents depositing sand, creating the current coastal dunes and backing estuaries.

This process took time. The coast as we know it today finally emerged about 6,000 years ago.

Even before this date, new habitats emerged favourable to human occupation.

In 1975 excavations at Stuarts Point, a very large oyster and cockle midden on the inner barrier north of the present estuary of the Macleay, revealed an occupation date of 9320 ± 160 BP (Before Present). Prior to that result, the earliest coastal date had been 6444 ± 74 BP for the basal levels of the Seelands dig in the Clarence about 12 kilometres northwest of Grafton.

On the Western Slopes and Plains, the earliest certain occupation date we have is much later than the coast, with an uncalibrated age of 5450 ± 100 years BP at Graman near Inverell.

On the Tableland, the earliest certain occupation date that we presently have is an uncalibrated age of 4300 years ago from Bendemeer. However, analysis done by Wendy Beck suggests that the resource base would have allowed targeted visits from at least the start of the Holocene, with permanent settlement possible from perhaps 6,000 years.

It is frustrating that we cannot sketch out the story in more detail. What we can say with a degree of certainty is that New England’s Aboriginal peoples were entering a golden age that would last to European invasion.

I will tell you this story in a later series of columns.

This post was prepared as a column for the on-line edition of the Armidale Express. I am repeating the columns here with a lag because they are not all on line outside subscription. You can see all the Belshaw World and History Revisited/History Matters columns by clicking here for 2009, here for 2010, here for 2011, here for 2012, here for 2013, here for 2014, here for 2015,  here for 2016, here  2017, here 2018, here 2019, here 2020 

The Aboriginal peopling of New England. How the New England landscape went through dramatic changes

The Byron landslip scar. This is the fifth in a series on the Aboriginal peopling of New England drawn from the introductory course I have been running on New England's history.

Aboriginal oral tradition records memories of great floods as the sea rushed in. These are usually attributed to large scale sea level rises as the icy conditions of the Last Glacial Maximum (21,000 to 15,000 years ago) eased and sea levels rose.

I suspect that’s broadly true, but they may also included memories of submarine landslide induced tsunamis, many of which occurred over the last 25,000 years along the Southern Queensland and Northern NSW coasts.

These tsunamis came about because of land collapses along the steeply sloping continental shelf. These collapses sent great blocks of rock and sediment plunging down the steeply sloping shelf out to sea over distances up too 100km and depths of 3,000m. You can imagine the effects on sea levels.

While spectacular, these changes were only a small part of the challenges faced by Australia’s Aboriginal peoples.

In my last column, I discussed what the Aboriginal occupation of New England might have looked like perhaps 40,000 years ago.

The Aborigines had arrived on the ancient content called Sahul at a time when the climate was colder but damper.

From perhaps 25,000 years ago, the environment deteriorated significantly.

Globally, the ice spread. As it did, the climate became colder and drier, deserts spread and trees retreated. This climatic regime peaked during the Last Glacial Maximum 21,000 to 15,000 years ago.

Sahul became very dry, both intensely hot and intensely cold. Sea levels fell by 60+ metres to perhaps 130 metres below current levels. Sea temperatures fell to 2-4 degrees C below those of today.

The effects across New England were dramatic. In the west, there were cold arid conditions. The deserts expanded eastwards. Stream flow was reduced. Trees and animals retreated.. In the east, the falling sea levels revealed a rugged inhospitable shore. While the coastal areas remained relatively well watered, food resources would have been reduced.

On the New England Tablelands, average temperatures fell by perhaps 8 degrees C. The Tablelands marked the start of a region of cold steppe and scattered sub-alpine woodland sweeping down through the southern Snowy Mountains into Tasmania, making it an inhospitable region for human habitation.

Faced with these changing conditions, the Aborigines would have been forced to retreat to refuge areas where food was still available. Some groups would have perished.

Better conditions lay ahead, but challenges had to be surmounted first.

This post appeared as a column in the on-line edition of the Armidale Express on 23 April 2020. I am repeating the columns here with a lag because they are not all on line outside subscription. You can see all the Belshaw World and History Revisited/History Matters columns by clicking here for 2009, here for 2010, here for 2011, here for 2012, here for 2013, here for 2014, here for 2015,  here for 2016, here  2017, here 2018, here 2019, here 2020 

The Aboriginal peopling of New England - What did Aboriginal life look like in New England 40,000 years ago?

Over c48,000 years, Tableland lagoons such as Little Llangothlin have provided a potential resource for Aboriginal people. This is the fourth in a series on the Aboriginal peopling of New England drawn from the introductory course I have been running on New England's history.

In my last column I suggested that while we had no direct archaeological evidence, the pattern of archaeological dates across Sahul suggested that first Aboriginal occupation of the broader New England may have taken place around 40,000 years ago.

Given the present absence of archaeological evidence, what might this occupation have looked like? To start answering this question, we need to start with New England’s geography.

In the east, the coastline as we know it today with its rich estuarine and marine resources did not exist and would not do so for another 34,000 years.

Sea levels were 60 metres lower than present. Because the continental shelf in this part of Australia is generally relatively narrow and steep sloping, the land revealed by the lower waters was often rugged, falling away to the then coastline,

The rivers from the Tablelands that now meander to the sea would have been faster flowing, their courses straighter with smaller estuaries. However, while the coastal environment was not as rich as it would later be, the combination of coastal, riverine and land environments would have been sufficient to support human occupation.

Inland, the Western Slopes and Plains would have been relatively well watered and potentially rich in resources. Again, it seems unlikely that the area was left vacant.

Further force is provided to this tentative conclusion in that in moving south whether by the inland or coastal routes, the advancing Aborigines would have passed through the broader New England. 

But what about that bit in the middle, the New England Tablelands? This was a less rich area in food terms, making occupation less likely.

In the absence of early dates, Wendy Beck, Robert Hayworth and John Appleton examined what resources might have been available to the Aborigines on the New England in the lagoons that run along the spine of the Tablelands.

The lagoons and especially Little Llangothlin have been studied because their long existence (c48,000 years) provides a useful record of change over time. They concluded that the combination of megafauna with lagoon resources could have provided a base for at least seasonal visits.

All this is surmise based on circumstantial evidence. We may never know because of the scale of changes that have taken place over the last forty thousand years. On the coast, for example, changing sea levels mean that many potential occupation sites have been buried under water or later silt deposits.

Despite such problems, I do believe that we can learn more through the type of studies pioneered by Wendy and her colleagues.

Note to readers: This post appeared as a column in the on-line edition of the Armidale Express Extra on 17 April 2020. I am repeating the columns here with a lag because they are not all on line outside subscription. You can see all the Belshaw World and History Revisited/History Matters columns by clicking here for 2009, here for 2010, here for 2011, here for 2012, here for 2013, here for 2014, here for 2015,  here for 2016, here  2017, here 2018, here 2019, here 2020 

The peopling of New England - Aboriginal people's arrival in New England

Aboriginal settlement of Sahul: by 40,000 years ago, the ancestors of Australias Aboriginal peoples had occupied the entire continent known as Sahul. This is the third in a series on the Aboriginal peopling of New England drawn from the introductory course I have been running on New England's history.

If the ancestors of Australia’s Aboriginal peoples reached the large continent known as Sahul perhaps 65,000 years ago, how and when did they reach the broader New England?

To start answering this question, consider the illustration to this column from Alana Coper et al. It shows the land boundaries of the mega-continent of Sahul during the Last Glacial maximum when sea levels were much lower.

The red lines suggest possible settlement paths; the black dates archaeological dates where kya stands for a thousand years. Ignore the other elements.

The Aboriginal ancestors arrived in Sahul during the Pleistocene, a period of repeated ice ages broken by warmer periods. They arrived at a benign time with relatively comfortable temperatures and a higher rainfall sufficient to fill the lakes and rivers.

The archeological dates shown in black suggest that by 40,000 years ago the descendents of those first settlers had occupied the entire continent of Sahul from Papua and surrounding islands in the north to Tasmania in the far south.

The migration paths are subject to some dispute. One school of thought is that migration went down the east coast.

I disagree. I think that it is most likely that migration proceeded down the western slopes and immediate western plains where there was water and easier immigration paths.

Whatever the exact path, it seems clear that by 40,000 years ago Sahul was occupied. Herein lies a problem, for the dates we have for the broader New England are all later.

The Cuddie Springs site near Brewarrina suggests occupation as long ago as 35,000 years BP. However, dates here have been subject to considerable dispute.

Excluding Cuddie Springs, we have a date of greater than 20,200 years BP (Before Present) from a hearth at Glennies Creek 35 kilometres north of Branxton in the Hunter, while a site on a former terrace of Wollombi Brook near Singleton suggested a date range of 18,000-30,000 years BP. At Moffats Swamp near Raymond Terrace, a date of 17,000 years BP was obtained.

On the Liverpool Plains, Aboriginal occupation has been dated to at least 19,000 years BP. Further north in South-East Queensland, the Wallen Wallen Creek site on what is now North Stradbroke Island shows continuous occupation from about 20,000 years ago.

While these dates are all later, Aboriginal peoples moving south must have passed through the broader New England, so we can reasonably assume some Aboriginal occupation by at least 40,000 years ago, probably earlier.

In my next column, I will discuss what that occupation might have looked like. 

Note to readers: This post appeared as a column in the Armidale Express Extra on 8 April 2020. I am repeating the columns here with a lag because they are not all on line outside subscription. You can see all the Belshaw World and History Revisited/History Matters columns by clicking here for 2009, here for 2010, here for 2011, here for 2012, here for 2013, here for 2014, here for 2015,  here for 2016, here  2017, here 2018, here 2019, here 2020 

The peopling of New England - Mysteries of migration

Digging deep: Evidence from the Madjedbebe rock shelter suggests early occupation from 65,000 years ago plus or minus 5,000 years.This is the second in a series on the Aboriginal peopling of New England drawn from the introductory course I have been running on New England's history.

In my last column, I spoke of the mysterious Denisovans, a new hominid species only discovered in 2010. They are significant to Australian history because it is clear that the ancestors of both the Papuans and Australia’s Aboriginal peoples met and mated with them on their journey to Sahul, the name given to the continent of which both Australia and Papua New Guinea were once part.

Over the next few columns I will tell you a little of the remarkable story of Aboriginal occupation of Sahul, including New England. It’s a story still shrouded in mystery and uncertainty, but we know enough now to at least paint a broad picture.

We do not know exactly when the ancestors of Australia’s Aboriginal peoples arrived on Sahul. The earliest date we have comes from excavations at the Madjedbebe rock shelter in Kakadu near Jabiru. There earliest occupation was dated to 65,000 years plus or minus 5,000 years.

There have been some suggestions of earlier possible dates based on circumstantial evidence such as fire patterns. Most recently, an excavation at Moyjil Port Ritchie near Warnambool identified a possible hearth dating to 120,000 years ago. However, the team was cautious in their conclusions in the absence of any associated artefacts.

The evidence from Madjedbebe also suggests a sophisticated material culture from an early date. This is consistent with an emerging body of evidence that suggests that earlier hominin species including anatomically modern humans were far more advanced and at an earlier period than previously realized.

This bears upon the question of just how the ancestors of the Aboriginal and Papuan peoples reached Sahul.

The old view based upon then perceptions of “primitiveness” saw the original settlers almost as castaways, small groups who came by accident. This now seems highly unlikely and for two reasons.   

The first is that we now know that earlier peoples were far more capable of crossing open water than previously realized. The great voyages from East Asia into Polynesia are a later and very dramatic example.

The second reason is that population analysis suggests that the survival and then expansion of the early human occupants of Sahul required a minimum foundation population measured in at least the low thousands. To my mind, there are likely to have been a number of movements spaced over time, possibly using different paths.

We don’t know what caused these migrations.

It may have been because of population pressures on existing ranges or because of pressures created by in-migration from other groups. There may have been natural disasters or, perhaps, just the normal human spirit wishing to explore new territories.

We may never know the answers here. However, we do more about what happened once the Aboriginal ancestors reached Sahul.

Note to readers: This post appeared as a column in the Armidale Express Extra on 1 April 2020. I am repeating the columns here with a lag because they are not all on line outside subscription. You can see all the Belshaw World and History Revisited/History Matters columns by clicking here for 2009, here for 2010, here for 2011, here for 2012, here for 2013, here for 2014, here for 2015,  here for 2016, here  2017, here 2018, here 2019, here 2020 

The peopling of New England - the mysterious Denisovans

Neanderthal cousins: Artists reconstruction of a Denisovan girl based on the combination of skeletal and DNA evidence.This is the first in a series on the Aboriginal peopling of New England drawn from the introductory course I have been running on New England's history.

We all carry our ancestry within us, imprinted in our DNA. We all know this in part because it provides the base for the increasingly popular ancestry DNA tests. What is perhaps less recognised is the way in which the science of genomics has totally transformed our knowledge of the deep human past. 

Genomics, an interdisciplinary field of biology, focuses on the structure, function, evolution, mapping, and editing of genomes. A genome is an organism's complete set of DNA, including all of its genes.

Genomics allows us to map and compare DNA from even ancient specimens. It allows us to map changes over time, and to estimate when certain changes might have taken place. This has resulted in a knowledge explosion.

The mysterious Denisovans are a case in point.

Denisova Cave lies in the Altai Mountains in south-central Siberia near the border with Kazakhstan, China and Mongolia.

In 2010, a Russian team announced that the DNA analysis of a juvenile female finger bone from the site had revealed a new hominin species that they named the Denisovans after the cave. The Denisovans were cousins to the European based Neanderthals, but had separated from them several hundred thousand years before.

This was remarkable enough, but more was to follow. DNA analysis of other remains and of modern human populations suggested that the Denisovans were widely spread across Asia with two distinct lines, one in East Asia, a second in South East Asia.

Further, the results show that the Denisovans overlapped with the Neanderthals at Denisova and with both Homo Erectus and anatomically modern humans in East and South East. The widespread nature of the Denisovan trace in dispersed anatomically modern human populations suggests extensive interbreeding with multiple Denisovan populations.

The DNA analysis also revealed that in their long journey out of Africa to the ancient continent called Sahul, the ancestors of the Papuans and Australian Aborigines had met and mated with the Denisovans.

This mating probably took place in what is now South East Asia close to Sahul. However, the trace is so strong among Papuans that it raises the possibility that the Denisovans may have lived in Papua or nearby islands until as recently 30,000 years ago.

This date is well within the period of Aboriginal occupation of Sahul. It raises an intriguing question: if the Denisovans were in Papua, then the northern extension of Sahul, did they penetrate further south into what is now the Australian continent?

Note to readers: This post appeared as a column in the Armidale Express Extra on 25 March 2020. I am repeating the columns here with a lag because they are not all on line outside subscription. You can see all the Belshaw World and History Revisited/History Matters columns by clicking here for 2009, here for 2010, here for 2011, here for 2012, here for 2013, here for 2014, here for 2015,  here for 2016, here  2017, here 2018, here 2019, here 2020 

Genomic analyses inform on migration events during the peopling of Eurasia

Another paper that I missed out on was this 2016 Nature paper "Genomic analyses inform on migration events during the peopling of Eurasia" The abstract follows:

High-coverage whole-genome sequence studies have so far focused on a limited number1 of geographically restricted populations2,3,4,5, or been targeted at specific diseases, such as cancer6. Nevertheless, the availability of high-resolution genomic data has led to the development of new methodologies for inferring population history7,8,9 and refuelled the debate on the mutation rate in humans10. Here we present the Estonian Biocentre Human Genome Diversity Panel (EGDP), a dataset of 483 high-coverage human genomes from 148 populations worldwide, including 379 new genomes from 125 populations, which we group into diversity and selection sets. We analyse this dataset to refine estimates of continent-wide patterns of heterozygosity, long- and short-distance gene flow, archaic admixture, and changes in effective population size through time as well as for signals of positive or balancing selection. We find a genetic signature in present-day Papuans that suggests that at least 2% of their genome originates from an early and largely extinct expansion of anatomically modern humans (AMHs) out of Africa. Together with evidence from the western Asian fossil record11, and admixture between AMHs and Neanderthals predating the main Eurasian expansion12, our results contribute to the mounting evidence for the presence of AMHs out of Africa earlier than 75,000 years ago. 

Pagani, L., Lawson, D., Jagoda, E. et al. Genomic analyses inform on migration events during the peopling of Eurasia. Nature 538, 238–242 (2016). https://doi.org/10.1038/nature19792

The Moyjil site, south-west Victoria: possible hominin occupation c 120,000 years ago

This another of those articles that I missed, the results of a dig at Moyjil Port Ritchie at the entrance to the Hopkins River, Warnambool on Victoria's south western coast. The dig investigated a charcoal and burnt stone feature associated with a scattered midden. Dating indicates a date around 120,000 years ago with the evidence marginally supporting a cultural over natural origin.

The abstract follows:

Claims for a human presence in Australia beyond 60,000 years ago must have a strong evidence base associated with rigorous methodology and intense scrutiny. In this light we present excavation results for Charcoal and Burnt Stone Feature #1 (CBS1) located within coastal dune sediments at Moyjil (Point Ritchie), Warrnambool, that independent geomorphic and OSL dating indicates is of Last Interglacial age (~120,000 years ago). While on plausibility grounds the cultural status of a feature of such great antiquity in Australia is unlikely, a cultural origin for CBS1 is less easily dismissed if assessed with an age-independent methodology. A broad range of macroscale discrimination criteria has been used to assess whether CBS1 is either a cultural hearth or a natural feature such as a burnt tree stump. On balance, evidence marginally supports a cultural origin over a natural origin. However, the absence of associated stone artefacts and faunal remains and the presence of burnt root wood precludes definitive statements on the cultural status of the feature. Our case study is methodologically instructive in terms of the potential complexities and issues of equifinality involved in the archaeological identification of ancient hearths. 

McNiven Ian J. , Crouch Joe , Bowler Jim M. , Sherwood John E. , Dolby Nic , Dunn Julian E. Stanisic John (2018) The Moyjil site, south-west Victoria, Australia: excavation of a Last Interglacial charcoal and and burnt stone feature — is it a hearth?. Proceedings of the Royal Society of Victoria 130, 94-116. https://doi.org/10.1071/RS18008

Comment

The results attracted considerable interest at the time because they seemed to push back the date of Aboriginal occupation of the continent to perhaps 120,000 years. The abstract is cautious in its conclusions about cultural as opposed to natural origin.

As we get more dates from Asia, the possibility of earlier hominin occupation of Sahul becomes more plausible.  The issue that then arises is whether they are Aboriginal or an earlier hominin species such as the Denisovans, given the tension between earlier dates and some of the dates attached to Aboriginal occupation by genomic modelling.

A note on cave art in Borneo

Twelve months ago, 7 November 2018, a team of researchers published a letter in Nature outlining new discoveries in cave art in Borneo. I missed it at the time. hat tip to Iain Davidson who posted a link on the UNE Archaeology Society Facebook page.

The piece adds to our understanding of the early world the Australian Aborigines travelled through to reach Sahul.

Abstract

Figurative cave paintings from the Indonesian island of Sulawesi date to at least 35,000 years ago (ka) and hand-stencil art from the same region has a minimum date of 40 ka1. Here we show that similar rock art was created during essentially the same time period on the adjacent island of Borneo. Uranium-series analysis of calcium carbonate deposits that overlie a large reddish-orange figurative painting of an animal at Lubang Jeriji Saléh—a limestone cave in East Kalimantan, Indonesian Borneo—yielded a minimum date of 40 ka, which to our knowledge is currently the oldest date for figurative artwork from anywhere in the world. In addition, two reddish-orange-coloured hand stencils from the same site each yielded a minimum uranium-series date of 37.2 ka, and a third hand stencil of the same hue has a maximum date of 51.8 ka. We also obtained uranium-series determinations for cave art motifs from Lubang Jeriji Saléh and three other East Kalimantan karst caves, which enable us to constrain the chronology of a distinct younger phase of Pleistocene rock art production in this region. Dark-purple hand stencils, some of which are decorated with intricate motifs, date to about 21–20 ka and a rare Pleistocene depiction of a human figure—also coloured dark purple—has a minimum date of 13.6 ka. Our findings show that cave painting appeared in eastern Borneo between 52 and 40 ka and that a new style of parietal art arose during the Last Glacial Maximum. It is now evident that a major Palaeolithic cave art province existed in the eastern extremity of continental Eurasia and in adjacent Wallacea from at least 40 ka until the Last Glacial Maximum, which has implications for understanding how early rock art traditions emerged, developed and spread in Pleistocene Southeast Asia and further afield.
M. Aubert, P. Setiawan, A. A. Oktaviana, A. Brumm, P. H. Sulistyarto, E. W. Saptomo, B. Istiawan, T. A. Ma’rifat, V. N. Wahyuono, F. T. Atmoko, J.-X. Zhao, J. Huntley, P. S. C. Taçon, D. L. Howard & H. E. A. Brand, Palaeolithic cave art in Borneo,  Nature 564, 254–257 (2018) doi:10.1038/s41586-018-0679-9

Homo luzonensis, Denisovans, Papuans and the the Australian Aborigines - more evidence from the deep past

Because of issues associated with my move to Armidale, it is some considerable time since I last reported on the continuing research into the deep human past, research that affects our understanding of Aboriginal history.

While I have been relatively off-line, regular commenter John B has been emailing me material. It now seems an appropriate point to bring that material on line. The long post that follows reports on three recent studies, concluding with a short discussion. My continued indebtedness to John B will be apparent.

Homo Luzonensis 

In April 2019, a group of researchers reported on the results of exploration at Calloa Cave in the Philippines, suggesting the discover of another hominin species that they named Homo luzonensis, dating to about 67,000 years ago.

The map from the paper is shown, including land that would have been revealed at various sea levels below the present. The abstract from the paper is set out below. 

"A hominin third metatarsal discovered in 2007 in Callao Cave (Northern Luzon, the Philippines) and dated to 67 thousand years ago provided the earliest direct evidence of a human presence in the Philippines. Analysis of this foot bone suggested that it belonged to the genus Homo, but to which species was unclear. Here we report the discovery of twelve additional hominin elements that represent at least three individuals that were found in the same stratigraphic layer of Callao Cave as the previously discovered metatarsal. These specimens display a combination of primitive and derived morphological features that is different from the combination of features found in other species in the genus Homo (including Homo floresiensis and Homo sapiens) and warrants their attribution to a new species, which we name Homo luzonensis. The presence of another and previously unknown hominin species east of the Wallace Line during the Late Pleistocene epoch underscores the importance of island Southeast Asia in the evolution of the genus Homo."
Florent Détroit, Armand Salvador Mijares, Julien Corny, Guillaume Daver, Clément Zanolli, Eusebio Dizon, Emil Robles, Rainer Grün & Philip J. Piper, A new species of Homo from the Late Pleistocene of the Philippines, Nature volume 568, pages 181–186 (2019) Published on-line 10 April 2019, accessed 22 October 2019 

That same day (10 April), BBC Science Paul Rincon provided a useful popular summary in Homo luzonensis: New human species found in Philippines.The article included this chart derived from the Smithsonian which I thought provided a useful graphic.

The BBC article as well as other commentary quotes Professor Chris Stringer, from London's Natural History Museum. For those who follow Twitter, Professor Stringer is an active tweeter - @ChrisStringer65.

John kindly sent me a press release apparently issued by Professor Stringer at the time. This is set out below. I have not been able to find a link to the original but have included it in full because of the overview it provides.

"Homo Luzonensis -  a new human species from island south east Asia

After the remarkable finds of the diminutive Homo floriensis were published in 2004, I said that the experiment in human evolution conducted on Flores could have been repeated on many of the other islands in the region. That speculation has seemingly been confirmed on the island of Luzon in the Philippines, nearly 3,000 km away. 13 fossil human remains - teeth, hand and foot bones, and part of a femur from at least 3 adults and immature individuals have been recovered from excavations at Callao Cave since 2007. They have been dated to at least 50,000 years old, are small in size, particularly the teeth, and they show a distinctive combination of primitive and and derived traits sufficient for the authors of the paper in Nature to create a new human species for them: Homo luzonensis. They suggest that some of the hand and foot bones show features also present in much more ancient australopiths ("southern apes") found in Africa, and interpreted as adaptations for life in the trees.

So, do these finds really represent a new species, and what do they add to the story of human evolution? Given the small size of the sample, some scientists will question the wisdom of creating a new species based on such limited material, while others such as me wonder whether Luzon find might eventually turn out to be a variant of the already known Homo floresiensis, despite some clear differences. And we know that island isolation can be a catalyst for some odd evolutionary changes, including reversion to apparently primitive states. Nevertheless, for the moment, it is probably reasonable to accept the new species, at least provisionally, while awaiting more finds.

As for its origins and fate, they remain mysterious. As with floresiensis, expert opinion will probably be divided. Some will argue that the primitive features of luzonensis are evidence of a pre- Homo erectus dispersal out of Africa, perhaps more than 2 million years ago. floresiensis and luzonensis would represent some of the last survivors of that early wave, lingering on at the fringes of the inhabited world. Others would prefer to regard these island forms as descendants of Homo erectus, subject to isolation and island dwarfing over a considerable period of time. And given two such populations in the remote islands of south east Asia, others like me might consider they represent remnants of a dispersal of an original floresiensis or luzonensis -like founder lineage that originated somewhere like the island of Sulawesi. As for the fate of luzonensis, it is too early to say whether the spread of Homo sapiens into the region at least 50,000 years ago might have been factor in its disappearance, as has been suggested for floresiensis.

An extra layer of complexity in the region has been added by recent research on the Denisovans, an archaic population of humans originally identified from ancient DNA recovered from human fossils in Denisova Cave, Siberia. The additional existence of late Denisovan-like populations in south east Asia had been inferred from the presence of related DNA in extant Asian and Oceanian people, but recent research indicates at least three separate and varied Denisovan-like sources, at least one of which probably lived in the same wide biogeographic zone as floresiensis and luzonensis. We are currently far from establishing which fossils in the region might represent such populations, but it is probable that the spread of Denisovan-like people into the region was a separate and much later event than those involving floresiensis and luzonensis." Ends

Another who commented on the Luzon discoveries was Professor John Hawks. His New species of hominin from Luzon appeared on  his blog on 10 April 2019 and in the online journal Sapiens at the same time. It covers some of the same ground as Professor Stringer's comment, but with more focus on the details of the evidence.

Multiple Deeply Divergent Denisovan-related ancestries in Papuans 

 At the same time as the Luzonensis results were reported,  another paper was released in Cell entitled Multiple Deeply Divergent Denisovan-related ancestries in Papuans. 

The abstract reads:

"Genome sequences are known for two archaic hominins-Neanderthals and Denisovans-which interbred with anatomically modern humans as they dispersed out of Africa. We identified high-confidence archaic haplotypes in 161 new genomes spanning 14 island groups in Island Southeast Asia and New Guinea and found large stretches of DNA that are inconsistent with a single introgressing Denisovan origin. Instead, modern Papuans carry hundreds of gene variants from two deeply divergent Denisovan lineages that separated over 350 thousand years ago. Spatial and temporal structure among these lineages suggest that introgression from one of these Denisovan groups predominantly took place east of the Wallace line and continued until near the end of the Pleistocene. A third Denisovan lineage occurs in modern East Asians. This regional mosaic suggests considerable complexity in archaic contact, with modern humans interbreeding with multiple Denisovan groups that were geographically isolated from each other over deep evolutionary time."
Jacobs GS, Hudjashov G, Saag L, Kusuma P, Darusallam CC, Lawson D, Mondal M, Pagani L, Ricaut FX, Stoneking M, Metspalu M, Sudoyo H, Lansing JS, Cox MP, Multiple Deeply Divergent Denisovan-related ancestries in Papuans, Cell. 2019 May 2;177(4):1010-1021.e32. doi: 10.1016/j.cell.2019.02.035. Epub 2019 Apr 11.Accessed 23 October 2019

On 11 April, EuekaAlert carried a press release from the Max Planck Institute for Evolutionary Anthropology. I have set this out below in full because it provides another perspective.

"Multiple Denisovan-related ancestries in Papuans 
 DNA sequences from Indonesia and New Guinea reveal new branches of the Denisovan family tree

   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.

Divergent Denisovan lineages

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.

Missing data bias scientific interpretation

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." Ends

Adaptive archaic introgression of copy number variants and the discovery of previously unknown human genes    

On 18 October 2019, Science published another study under the catchy (!) title Adaptive archaic introgression of copy number variants and the discovery of previously unknown human genes. The above graphic reproduced from the article provides an effective schematic.

In this case, I am not providing the full abstract (you will find it here) because of length as well as complexity. However, a short extract follows:

"Copy number variants (CNVs) are subject to stronger selective pressure than single-nucleotide variants, but their roles in archaic introgression and adaptation have not been systematically investigated. We show that stratified CNVs are significantly associated with signatures of positive selection in Melanesians and provide evidence for adaptive introgression of large CNVs at chromosomes 16p11.2 and 8p21.3 from Denisovans and Neanderthals, respectively. Using long-read sequence data, we reconstruct the structure and complex evolutionary history of these polymorphisms and show that both encode positively selected genes absent from most human populations. Our results collectively suggest that large CNVs originating in archaic hominins and introgressed into modern humans have played an important role in local population adaptation and represent an insufficiently studied source of large-scale genetic variation."
PingHsun Hsieh, Mitchell R. Vollger, Vy Dang, David Porubsky, Carl Baker, Stuart Cantsilieris, Kendra Hoekzema1, Alexandra P. Lewis, Katherine M. Munson, Melanie Sorensen, Zev N. Kronenberg, Shwetha Murali, Bradley J. Nelson1, Giorgia Chiatante, Flavia Angela Maria Maggiolini, Hélène Blanché, Jason G. Underwood, Francesca Antonacci, Jean-François Deleuze, Evan E. Eichler, Adaptive archaic introgression of copy number variants and the discovery of previously unknown human genes, Science  18 Oct 2019:Vol. 366, Issue 6463, eaax2083 DOI: 10.1126/science.aax2083, accessed 22 October 2019

Discussion

In sending me material, John B commented (24 April 2019): "It is increasingly looking likely Jim that the Aboriginals who first colonised Australia were locals to the region and not in transit through it, my suspicions of the original Out of Africa single origin hypothesis, replacement hypothesis, or recent African origin model continue to be confirmed. Archaic diversity, I do like that descriptor and the picture it conveys."

John and I have been talking about these issues now for a number of years. Over that time, new research discoveries have added to our understanding, but also created an unexpectedly complex and uncertain  picture. 

In 2017, reports of results from the excavations at the Madjedbebe rock shelter, The lessons and questions from Madjedbebe, pushed back the date of human occupation of Northern Australia to perhaps 65,000. I was going to write Aboriginal occupation but, while it seems probable, we don't actually know that the continent of Sahul was first occupied by the descendants of today's Aboriginal Australians.

In October 2016 in a paper entitled A genomic history of Aboriginal Australia, by Anna-Sapfo Malvinas, Michael C Westerway et all, the authors concluded that:

• Aboriginal Australians and Papuans diverged from Eurasians and estimate 51–72 kya, following a single out-of-Africa dispersal, and subsequently admixed with archaic populations
• Papuan and Aboriginal Australian ancestors diversified 25–40 thousand years ago (kya), suggesting pre-Holocene population structure in the ancient continent of Sahul (Australia, New Guinea and Tasmania). However, all of the studied Aboriginal Australians descend from a single founding population that differentiated ~10–32 kya
• We infer a population expansion in northeast Australia during the Holocene epoch (past 10,000 years) associated with limited gene flow from this region to the rest of Australia, consistent with the spread of the Pama–Nyungan languages.   

I will leave aside the last conclusion for it raises another set of issues that is important to the history of Aboriginal Australia but is outside the scope of this post.

At the time, the estimate of 51–72 kya for divergence from Eurasians following a single out-of-Africa dispersal made me uncomfortable because the archaeological evidence was already suggesting possible early dates for human occupation of Sahul that might possibly conflict with these time lines. The Madjedbebe results added to this discomfort: the suggested 65,000 years was remarkably close to the suggested 72kya out of Africa date.

Before going on, I note that all the dating techniques involve statistical analysis with confidence intervals. Apparent differences and inconsistencies may reflect no more than this.

 The latest discoveries covered in this blog post suggest that:

• Earlier hominum species were in South East Asia long before modern humans
• Those species had come in different waves and had diversified 
• Those species had crossed the Wallace Line, overcoming sea barriers. They may even have reached Sahul
• Those species and modern humans overlapped far more than previously realised, co-existing in various forms of relationships including inter-breeding
• Aboriginal and Papuan groups that formed the basis of later population may have lived in what is now SE Asian for extended periods before moving on, not just passing through.

In writing to me, John also noted:

"I have just been reading a Geology paper that mentioned the super volcano Toba eruption as the largest single event of its type so far known. It struck me that this could have been the event to precipitate human migration into Australia. We now understand that the arrival of H.sapiens into Oz occurred most likely as a bulk entry over a very short period then nobody else over millennia. Could Toba have been the push factor ?"

I am not convinced that there was a single pulse and am generally sceptical of attributions to volcanic eruptions. But still. As dates get pushed back, the possibility that the Toba eruption played a role in the movement of and ending of human species becomes more plausible! 

David Reich on who we are and how we got here

Over the last few weeks I have been binge watching YouTube videos about prehistory. I haven't been taking notes, simply immersing myself  in the latest content with a special focus on the latest results from DNA analysis. I suppose this approach lacks rigour, being more akin to the last minute approach I used to follow to get through exams, but I find that it works for me in providing structure and generating thoughts and linkages. 

As I listened, I thought how much our knowledge had changed and just how quickly.

This is a video of a talk given by Professor David Reich last year at Harvard: "Who we are and how we got here - Ancient DNA and the new science of the human past". This the second presentation I have seen on the same topic by Professor Reich, this is the link to the first. Both presentations follow  the release of his 2018 book of the same title.

The book has attracted some criticism not so much on the science but on some of the wording used. I haven't read the book, it seems to have got caught up in current preoccupations about language, but the presentation strikes me as scientifically rigorous and indeed quite fascinating.  It's quite a long video, over an hour, but will give you an insight into the way that scientific research is challenging our deeply held perceptions about the human past. 

Who were the first occupants of Sahul?

A largely complete, roughly 300,000-year-old skull from southeastern China appears to be the latest evidence challenging the dominant model of human evolution. The Hualongdong skull’s unique combination of features make the fossil a tantalizing clue to East Asia’s diverse hominin history. 

Researchers excavating a collapsed cave site unearthed the skull, formally known as Hualongdong 6 (HLD 6), along with additional partial fossils of archaic humans and animals, plus assorted stone tools, over the last decade or so. Using the ages of surrounding mineral deposits and other material in the cave, the team determined the skull and other remains were about 300,000 years old.

My regular commenter JohnB pointed me to this story. I will leave you to read it: Hualongdong Skull Is Latest Challenge To Dominant Human Evolution Model.

I think that there are several key points to note.

The first is that the simple out of Africa for the emergence of modern humans is, as John had argued, becoming increasingly uncertain. There may well have been multiple regional streams.This brings me into arguments that I lack the knowledge on which to comment.

The second point is that the Aborigines on their travels to Australia may well have travelled through a populated landscape. We do not know by whom or how many, but it was populated as measured by Denisovan genetic traces in Aborigines and Papuans. 

 All this raises the question of the who were the first settlers on Sahul, the name given to the ancient continent. We know, or seem to know, that early hominids arrived in the Philippines before Aboriginal settlement of Sahul. This was a longish sea journey suggesting that early hominids could travel by sea to new areas. So did they reach Sahul?

Because of the loss of skeletal remains and limitations on analysis in Australia, we may never get results here. But as more Asian results emerge, we may get a better precursor picture.

None of this detracts from the saga of the Aboriginal occupation of Sahul. It just indicates the need for care in the conclusions we draw, the arguments we mount based on those conclusions. 
 

The spreading Denisovans

This short piece by  Meilan Solly, in the Smithsonian ,The Hominins We’ve Been Calling Denisovans Are More Diverse Than Previously Thought, provides a very useful summary of current thinking.

So far the only Denisovan remains that have been found are from a cave in Siberia. But the DNA analysis suggests that their influence was wise spread, with several Denisovan groups.

The significance for New England history and the history of the Australian Aborigines in general is that while we now know that Aboriginal ancestors interacted with the Denisovans we do not know when and where. Had the Denisovans actually reached Sahul, prehistoric Australia, or was the interaction earlier. The second is the current view, in South East Asia.

The further back the dates of human occupation of Sahul are pushed, the more complex the story becomes. At 62,000 years, all things are (I guess) on the table.

New evidence on the Neanderthal/Denisovan overlap

Summary timeline for the archaeology, hominin fossils and hominin DNA retrieved from the sediments at Denisova Cave. All age ranges are shown at the 95.4% confidence interval. Bert Roberts,

Interesting paper by Zenobia Jacobs, Bo Li, Kieran O'Gorman and Richard Roberts all from the University of Wollongong in The Conversation:  Fresh clues to the life and times of the Denisovans, a little-known ancient group of humans (31 January 2018) .

The Denisova site is interesting because it is the only known site so far for the Denisovan species of hominin, the only site where Denisovans and Neanderthals overlapped. The latest dating results are summarised this way.

 The new studies show that hominins have occupied the site almost continuously through relatively warm and cold periods over the past 300,000 years, leaving behind stone tools and other artefacts in the cave deposits. 

Fossils and DNA traces of Denisovans are found from at least 200,000 to 50,000 years ago, and those of Neanderthals from between 200,000 and 100,000 years ago. The girl with mixed ancestry reveals that the two groups of hominins met and interbred around 100,000 years ago.

Both the Aborigines and Papuans have significant traces of Denisovan DNA suggesting that their ancestors met and mixed with the Denisovans on their journey to Sahul. An alternative but still less likely explanation is that the Denisovans had already reached Sahul at least in small numbers and the admixture occurred here.

I say this only because there is now an apparent tension that I do not understand between the archaeological dates and those generated by DNA analysis. The first presently suggests earliest occupation of perhaps 62,000 years ago based on archaeological dating, while the second suggests an out of Africa date for the Aborigines and Papuans of perhaps 51-72,000 years based on DNA modelling. There is still an overlap, but it has become too small for my comfort. .

I think that what is clear is that the new evidence is progressively changing our understanding of the human pattern of settlement in Eurasia and that this will necessarily change our understanding of Sahul's history.