Wednesday, April 8, 2020

Amazonian crops domesticated 10,000 years ago

IMAGE: FOREST ISLAND IN THE BOLIVIAN LLANOS DE MOXOS, ONE OF THE SITES WHERE ARCHAEOLOGICALEXCAVATIONS REVEALED THE EXISTENCE OF EARLY AND MIDDLE HOLOCENE HUMAN OCCUPATIONS INCLUDING BURIALS. view more

CREDIT: JOSÉ CAPRILES, PENN STATE

As agriculture emerged in early civilizations, crops were domesticated in four locations around the world -- rice in China; grains and pulses in the Middle East; maize, beans and squash in Mesoamerica; and potatoes and quinoa in the Andes. Now, an international team of researchers have confirmed a fifth domestication area in southwestern Amazonia where manioc, squash and other edibles became garden plants during the early Holocene, starting over 10,000 years ago.

"Our results confirm the Llanos de Moxos as a hotspot for early plant cultivation, and demonstrate that ever since their arrival, humans have caused a profound alteration of Amazonian landscapes, with lasting repercussions for habitat heterogeneity and species conservation," the researchers report today (Apr. 8) in Nature.

The Llanos de Moxos is a savannah of approximately 48,700 square miles located in the Beni Department of Bolivia in southwestern Amazonia. The landscape is dotted by earthworks, including raised fields, mounds, canals and forest islands. The researchers looked at the forest islands located within the vast savannah for signs of early gardening.

"We basically mapped large sections of forest islands using remote sensing," said José Capriles, assistant professor of anthropology, Penn State. "We hypothesized that the regularly shaped forest islands had anthropic origin.

However, as Umberto Lombardo, University of Bern, who leads the paper, noted, "Most circular forest islands are in fact artificial and irregular ones are not. There is not a clear pattern."

In fact, there are more than 4,700 artificial forest islands in the Llanos de Moxos savannah according to the researchers who "ground truthed" approximately 30 of these islands and showed that many might have served as human planting areas.

"Archaeological evidence for plant domestication is very poorly available, especially in Amazonia where the climate destroys most organic materials," said Capriles. "There is no stone in this area because it is an alluvial plain (water deposited) and it is hard to find evidence of early hunter-gatherers."

The researchers -- including Capriles; Lombardo, Heinz Veit from the University of Bern; Jose Iriarte and Lautaro Hilbert from the University of Exeter; and Javier Ruiz-Pérez from Pompeu Fabra University, Barcelona, Spain -- analyzed phytoliths, tiny mineral particles that form inside plants, from radio-carbon-dated samples taken from forest island archaeological excavations and sedimentary cores. The shape of the silica-based phytoliths depends on the plants in which they form, allowing archaeologists to identify the plants that were grown in the forest islands. The team found evidence of manioc -- cassava, yuca -- 10,350 years ago, and squash 10,250 years ago. Early maize appears 6,850 years ago.

Manioc, squash, maize and other carbohydrate-rich foods such as sweet potato and peanuts probably made up the bulk of the diet in Llanos de Moxos, supplemented by fish and large herbivores.

"Archaeologists, geographers and biologists have argued for many years that Southwestern Amazonia was a probable center of early plant domestication because many important cultivars like manioc, squash, peanuts and some varieties of chili pepper and beans are genetically very close to wild plants living here," said Lombardo, who was lead author on the paper. "However, until this recent study, scientist had neither searched for, nor excavated, old archaeological sites in this region that might document the pre-Columbian domestication of these globally important crops."

The researchers suggest that their data indicate that the earliest inhabitants of Southwestern Amazonia were not just hunter-gatherers, but engaged in plant cultivation in the early Holocene. The earliest people in the area may have arrived to the region already possessing a mixed economy.

Earliest humans in the Amazon created thousands of 'forest islands' as they tamed wild plants

The earliest human inhabitants of the Amazon created thousands of artificial forest islands as they tamed wild plants to grow food, a new study shows.

The discovery of the mounds is the latest evidence to show the extensive impact people had on the area. From their arrival 10,000 years ago they transformed the landscape when they began cultivating manioc and squash.

This led to the creation of 4,700 of the forest islands in what is now Llanos de Moxos in northern Bolivia, the team has found. This savannah area floods from December to March and is extremely dry from July to October, but the mounds remain above the water level during the rainy season allowing trees to grow on them. The mounds promoted landscape diversity, and show that small-scale communities began to shape the Amazon 8,000 years earlier than previously thought.

The research confirms this part of the Amazon is one of the earliest centres of plant domestication in the world. Using microscopic plant silica bodies, called phytoliths, found well preserved in tropical forests, experts have documented the earliest evidence found in the Amazon of manioc -10,350 years ago, squash - 10,250 years ago, and maize - 6,850 years ago. The plants grown on the forest islands were chosen because they were carbohydrate-rich and easy to cook, and they probably provided a considerable part of the calories consumed by the first inhabitants of the region, supplemented by fish and some meat.

The study, in the journal Nature, was conducted by Umberto Lombardo and Heinz Veit from the University of Bern, Jose Iriarte and Lautaro Hilbert from the University of Exeter, Javier Ruiz-Pérez from Pompeu Fabra University and José Capriles from Pennsylvania State University.

The study involved an unprecedented large scale regional analysis of 61 archaeological sites, identified by remote sensing, now patches of forest surrounded by savannah. Samples were retrieved from 30 forest islands and archaeological excavations carried out in four of them.

Dr Lombardo said: "Archaeologists, geographers, and biologists have argued for many years that southwestern Amazonia was a probable centre of early plant domestication because many important cultivars like manioc, squash, peanuts and some varieties of chili pepper and beans are genetically very close to wild plants living here. However, until this recent study, scientist had neither searched for, nor excavated, old archaeological sites in this region that might document the pre-Columbian domestication of these globally important crops."

Professor Iriarte said: "Genetic and archaeological evidence suggests there were at least four areas of the world where humans domesticated plants around 11,000 years ago, two in the Old World and two in the New World. This research helps us to prove South West Amazonia is likely the fifth.

"The evidence we have found shows the earliest inhabitants of the area were not just tropical hunter-gatherers, but colonizers who cultivated plants. This opens the door to suggest that they already ate a mixed diet when they arrived in the region."

Javier Ruiz-Pérez said: "Through an extensive archaeological survey including excavations and after analysing dozens of radiocarbon dates and phytolith samples, we demonstrated that pre-Columbian peoples adapted to and modified the seasonally flooded savannahs of south-western Amazonia by building thousands of mounds where to settle and by cultivating and even domesticating plants since the beginning of the Holocene."

Revolutionary new method for dating pottery sheds new light on prehistoric past

A team at the University of Bristol has developed a new method of dating pottery which is allowing archaeologists to date prehistoric finds from across the world with remarkable accuracy.

The exciting new method, reported in detail today in the journal Nature, is now being used to date pottery from a range of key sites up to 8,000 years old in Britain, Europe and Africa.

Pottery and the dating game

Archaeological pottery has been used to date archaeological sites for more than a century, and from the Roman period onwards can offer quite precise dating. But further back in time, for example at the prehistoric sites of the earliest Neolithic farmers, accurate dating becomes more difficult because the kinds of pottery are often less distinctive and there are no coins or historical records to give context.

This is where radiocarbon dating, also known as 14C-dating, comes to the rescue. Until now, archaeologists had to radiocarbon date bones or other organic materials buried with the pots to understand their age.

But the best and most accurate way to date pots would be to date them directly, which the University of Bristol team has now introduced by dating the fatty acids left behind from food preparation.

Professor Richard Evershed from the University of Bristol's School of Chemistry led the team. He said: "Being able to directly date archaeological pots is one of the "Holy Grails" of archaeology. This new method is based on an idea I had going back more than 20 years and it is now allowing the community to better understand key archaeological sites across the world.

"We made several earlier attempts to get the method right, but it wasn't until we established our own radiocarbon facility in Bristol that we cracked it. There's a particular beauty in the way these new technologies came together to make this important work possible and now archaeological questions that are currently very difficult to resolve could be answered."

How the method works

The trick was isolating individual fat compounds from food residues, perhaps left by cooking meat or milk, protected within the pores of prehistoric cooking pots. The team brought together the latest high resolution nuclear magnetic resonance spectroscopy and mass spectrometry technologies to design a new way of isolating the fatty acids and checking they were pure enough for accurate dating.

The team then had to show that the new approach gave dates as accurate as those given by materials commonly dated in archaeology, such as bones, seeds and wood. To do this the team looked at fat extracts from ancient pottery at a range of key sites in Britain, Europe and Africa with already precise dating which were up to 8,000 years old.

From the famous Sweet Track site in Somerset and several sites in the Alsace region of France, to the World Heritage site of Çatalhöyük in central Turkey and the famous rock shelter site of Takarkori in Saharan Africa, the new method was proven to date sites incredibly accurately, even to within a human life span.

Professor Alex Bayliss, Head of Scientific Dating at Historic England, who undertook the statistical analyses, added: "It is very difficult to overstate the importance of this advance to the archaeological community. Pottery typology is the most widely used dating technique in the discipline, and so the opportunity to place different kinds of pottery in calendar time much more securely will be of great practical significance."

Using the pottery calendar to better understand London's pre-history

In London, England, the new dating method has been used on a remarkable collection of pottery found in Shoreditch, thought to be the most significant group of Early Neolithic pottery ever found in the capital. The extraordinary trove, comprising 436 fragments from at least 24 separate vessels weighing nearly 6.5 kilos in total, was discovered by archaeologists from MOLA (Museum of London Archaeology).

The site appeared to date from the time when the first farmers came to Britain but accurately dating it was difficult until the Bristol team, using their new dating method on traces of milk fats extracted from the pots, showed the pottery was 5,500 years old. The team were able to date the pottery collection to a window of just 138 years, to around 3600BC.

The results indicate that around 5600 years ago the area around what is now Shoreditch High Street was used by established farmers who ate cow, sheep or goat dairy products as a central part of their diet. These people were likely to have been linked to the migrant groups who were the first to introduce farming to Britain from Continental Europe around 4000 BC - just 400 years earlier.

Jon Cotton, a consultant prehistorian working for MOLA, said: "This remarkable collection helps to fill a critical gap in London's prehistory. Archaeological evidence for the period after farming arrived in Britain rarely survives in the capital, let alone still in-situ. This is the strongest evidence yet that people in the area later occupied by the city and its immediate hinterland were living a less mobile, farming-based lifestyle during the Early Neolithic period."

The results from this site are a prime example of where pottery survives in circumstances that other organic materials do not, so using this revolutionary new method will unlock important information about our prehistoric past.

Monday, April 6, 2020

Societal transformations and resilience in Arabia across 12,000 years of climate change

Social, economic and cultural responses to climate change by ancient peoples highlight vulnerabilities of modern societies and the need for sustainable new solutions

Today, the Arabian Peninsula is one of the most arid regions in the world. But its climate has not always been the same, and the past has seen both greater aridity and more humidity at different points in time. As a region at risk of water stress in a heating world, Arabia is of significant interest to scientists studying climate change.

In the current study, archaeologists from the Max Planck Institute for the Science of Human History in Jena, Germany, conduct the first detailed comparison of human-environment interactions across Arabia, examining southeastern Arabia and the emerging record from northern Arabia. They find that ancient peoples responded to climate changes in a variety of ways, based on the region in which they lived and the environmental, social and technological resources available to them.

High mobility, water management, and economic transformation in northern Arabia

Approximately 10,000 years ago, Arabia saw a significant increase in rainfall and an expansion of lakes and vegetation which supported human settlements across the peninsula. In the millennia that followed, however, a series of extreme droughts led to drastic ecosystem changes.

In northern Arabia, the presence of large, shallow aquifers and seasonal playas facilitated survival through highly variable climatic conditions, including several centuries-long droughts. In particular, desert oases - including one in what is now the city of Jubbah - sustained human occupation, and the archaeological record indicates human presence in the surrounding Nefud Desert at multiple times during a 9000-year period. The discovery of the Jebel Oraf rockshelter on the fringes of the Jubbah oasis and a lakeside site with more than 170 hearths and remains of cattle show long-term habitation of the region. As Dr. Maria Guagnin explains, "pastoralist populations occupied the region repeatedly across millennia, relying on mobility and an extensive knowledge of the landscape and its resources to survive climatic changes and droughts."

During the 'Dark Millennium,' an arid period lasting from approximately 5,900 to 5,300 years ago during which much of Arabia is thought to have been uninhabitable, the researchers again find evidence of occupation at the Jubbah oasis. In other areas of northern Arabia, people constructed walls around oases, built landscape features to capture water runoff and began excavating wells. "Taken together," Dr. Huw Groucutt notes, "these finds indicate that the presence of extensive shallow aquifers, in combination with high population mobility, water management strategies and economic transformation, provided opportunities for the long-term survival of north Arabian populations."

Southeastern populations sought out the resource-rich coast in the face of droughts

Southeastern Arabia, in contrast with the north, seemingly enjoyed fewer sources of groundwater and saw a more direct correlation between the succession of ancient droughts and dramatic social change. After the Holocene Humid Phase, a subsequent climatic downturn lasting from 8,200 to 8,000 years ago brought effects so extreme that it is thought to have been linked to a shift from hunting and gathering to domesticated animal herding, according to previous research. Subsequent droughts (7,500 to 7,200 years ago and 6,500 to 6,300 years ago) correspond with declines in interior desert occupation, the development of herder and fisher communities on the coast, and the establishment of a maritime trade network between Arabian pastoralists and agricultural communities in Mesopotamia.

The extreme aridity of the 'Dark Millennium' brought about the abandonment of the southeast Arabian desert interior and the migration of populations to the Gulf coast. Previous research findings suggest, however, that even coastal populations felt the effects of strained resources. Earlier excavations at the seaside site of Ras al-Hamra reveal that Omani coastal populations from this period were in poor overall health. Specially arranged dugong (marine mammal) bone mounds excavated on the island of Akab in the United Arab Emirates suggest ritualized acts of consumption, perhaps a response to food scarcity.

Past responses highlight the need for sustainable solutions to confront climate change

Understanding the relationship between regional manifestations of climate change and adaptations that allow for societal resilience can provide valuable lessons for modern societies the world over. "For millennia, moving away from hard-hit regions was the main human response to severe climate downturns," says lead author Professor Michael Petraglia, "but with growing population sizes and an increasing investment in place, options for human mobility have decreased over time. In the same way, the rapid depletion of aquifers in recent years highlights the need for sustainable solutions to meet environmental challenges."

The researchers stress that taking action now to address the climate emergency is in the world's best interest. "Sometimes people dismiss climate change as something we don't need to worry too much about, because we've faced it before," notes Professor Nicole Boivin, director of the Institute's Department of Archaeology and a coauthor of the study. "But the scenarios we face now are unprecedented. Not only is human-caused climate change more unpredictable, but the options available to societies today are much more limited than those that allowed our ancestors to weather past changes."

Climate change encouraged colonization of South Pacific Islands earlier than first thought

UNIVERSITY OF SOUTHAMPTON

Research led by scientists at the University of Southampton has found settlers arrived in East Polynesia around 200 years earlier than previously thought.

Colonisation of the vast eastern Pacific with its few and far-flung island archipelagos was a remarkable achievement in human history. Yet the timing, character, and drivers of this accomplishment remain poorly understood.

However, this new study has found a major change in the climate of the region, which resulted in a dry period, coinciding with the arrival of people on the tiny island of Atiu, in the southern group of the Cook Islands, around 900AD.

Findings are published in the paper, 'Human settlement of East Polynesia earlier, incremental and coincident with prolonged South Pacific drought' in the journal PNAS.

"The ancestors of the Polynesians, the Lapita people, migrated east into the Pacific Ocean as far as Fiji, Tonga and Samoa, reaching them around 2800 years ago. But for almost 1500 years humans failed to migrate any further into the pacific," explains lead researcher, Professor David Sear of the University of Southampton. "Our research gives us a much more accurate timescale of when people first arrived in the region and helps answer some key questions about why they made their hazardous journey east."

A team of geographers, archaeologists and geochemists from the UK, New Zealand and the US, worked with the people of Atiu, to collect core samples of lake mud, charting over 6000 years of history. Back in the labs in UK and US, the mud samples were subjected to a range of analyses including new techniques for reconstructing precipitation, and detecting the presence of mammalian faeces.

Apart from fruit bats, the Southern Cook Islands never had mammal populations before humans settled there, so when the researchers found evidence of mammal faeces alongside other evidence for landscape disturbance and burning, it was a clear sign of the arrival of people. Within 100 years the first settlers, most likely from Tonga or Samoa, changed the landscape by burning native forest to make way for crops.

The team, including undergraduate and postgraduate students from the universities of Southampton and Washington, as well as scientists from Newcastle, Liverpool and Auckland universities, also examined lake sediments from Samoa and Vanuata. Using this data, they found evidence for a major climate change which coincided with the newly established arrival time of the settlers.

The data revealed a major change in the climate of the South Pacific region with the main rainbands that bring water to the archipelagos of Vanuatu, Samoa, Tonga and Fiji migrating north. The result was the driest period in the last 2000 years.

This led the researchers to conclude that, alongside growing populations, water stress drove decisions to make dangerous voyages, aided by changes in winds that enabled easterly sailing. Soon after the arrival of people to Atiu, the climate changed again. Rain returned to the eastern Pacific - supporting a rapid (c. 200 years) settlement of the remaining islands of Polynesia.

Professor Sear adds: "Today, changing climate is again putting pressures on Pacific island communities, only this time the option to migrate is not so simple. Within two centuries of first arrival those first settlers changed the landscape and the ecology, but were able to make a home. Pacific islanders now live with modified ecologies, permanent national boundaries and islands already occupied by people. The ability to migrate in response to changing climate is no longer the option it once was."

Thursday, April 2, 2020

Our direct human ancestor Homo erectus is older than we thought

UNIVERSITY OF JOHANNESBURG

Volume 90%

VIDEO: ONE OF OUR DIRECT HUMAN ANCESTORS IS OLDER THAN WE THOUGHT. THE CRADLE OF HUMANKIND NORTHWEST OF JOHANNESBURG, SOUTH AFRICA HAS YIELDED ITS FIRST HOMO ERECTUS FOSSIL, AND THE OLDEST... view more

CREDIT: THERESE VAN WYK, UNIVERSITY OF JOHANNESBURG

An unusual skullcap and thousands of clues have created a southern twist to the story of human ancestors, in research published in Science on 3 April.

The rolling hills northwest of Johannesburg are famous for fossils of human-like creatures called hominins. Because of this, the area is known as the Cradle of Humankind.

"During our field school excavations at Drimolen, a student began uncovering a cluster of fragments. We could see that they were parts of a skull. But they weren't immediately identifiable," says Ms Stephanie Baker.

Baker is a researcher and PhD candidate at the Palaeo-Research Institute at the University of Johannesburg. She manages research at the Drimolen fossil site in the Cradle of Humankind where the fragments of DNH 134 were found.

The international team was led by researchers from La Trobe University in Australia and Washington University in St. Louis in the United States.

Fossil forensics

Fossils that are millions of years old often come out of the soil in fragments. The fragments need to be rebuilt before researchers can confidently identify what kind of animal they came from.

"Over the course of the field season more and more fragments were uncovered. We began piecing them together. No one could decide what this skullcap was from, until one night it all came together - and we realised we were looking at a hominin!" she says. They named the skullcap DNH 134.

The next question was - what kind of hominin? The Cradle of Humankind has several different species of human ancestors and the Drimolen site had at least two kinds.

"This find really challenged us. We compared the assembled skullcap to all of the other examples of hominins in the Cradle area. Eventually, its teardrop shape and relatively big brain cavity meant we were looking at Homo erectus," says Baker.

Homo erectus is one of our direct human ancestors and is best known for migrating out of Africa into the rest of the world.

These hominins walked upright and were a more human-like species than the other hominins found in the Cradle. They had shorter arms and longer legs. They could walk and run for longer distances over the African grasslands than the others.

How old?

Once the question of 'which species?' was answered, two other huge questions presented themselves. How long ago was this individual alive? And how old were they when they died?

The researchers knew that no other Homo erectus fossils had ever been found in South Africa before. Even more surprising was the time period suggested by the soil layers the skull fragments were found in. "Before we found DNH 134, we knew that the oldest Homo erectusin the world was from Dmanisi in Georgia dating to 1.8 million years ago," says Baker.

Building a 3D puzzle over time

Trying to figure out how old fossils are from the caves west of Johannesburg is quite tricky. There were no volcanoes during the time of the hominins, so there are no ash layers to give the researchers quick age estimates, like they use for eastern African sites.

But while they were uncovering the fragments at Drimolen, they kept and recorded every clue they could find. This included fragments of small animals like bats and lizards, but also things like soil samples.

They can also tell exactly where in 3D-space in the Drimolen quarry each little fossil fragment was found.

Then the research team used every possible dating technique available to get the most accurate possible date for the deposit. This included Palaeomagnetic dating, Electron spin resonance, Uranium lead dating, and faunal dating.

Possible shifted, earlier origin

"We collated all of the dates from each of these techniques and together they showed that we had a very precise age. We now know that the Drimolen Main Quarry and all of the fossils in it, are dated from 2.04 to 1.95 million years ago," says Baker.

That means that DNH 134 is much older than the next oldest Homo erectus in Africa; and from Georgia.

"The age of the DNH 134 fossil shows that Homo erectus existed 150,000 to 200,000 years earlier than previously thought," says Professor Andy Herries. Herries is the project co-director with Ms Baker and lead researcher. He is Head of the Department of Archaeology and History, at La Trobe University in Australia and an associate in the Palaeo-Research Institute at UJ.

Because Homo erectus is one of our direct ancestors, the discovery has implications for the origins of modern humans.

"Until this find, we always assumed Homo erectus originated from eastern Africa. But DNH 134 shows that Homo erectus, one of our direct ancestors, possibly comes from southern Africa instead. That would mean that they later moved northwards into East Africa. From there they went through North Africa to populate the rest of the world," says Baker.

The skull is also unusual because it is the skull of a young Homo erectus.

"The Homo erectus skull we found, was likely aged between two and three years old when it died," says Herries.

Sharing a landscape

The age of the DNH 134 skullcap shows something else - that three species of early human ancestor lived in southern Africa at the same time at the Drimolen fossil site.

"We can now say Homo erectus shared the landscape with two other types of humans in South Africa, Paranthropus and Australopithecus," says Herries.

This might mean they needed to use different parts of the landscape to avoid competing with one another. For a start, they looked different.

Paranthropus robustus hominins were shorter than Homo erectus and Australopithecus, says Baker.

"Paranthropus robustus ate things like roots and tubers, which is why their teeth are really big. They used their enormous teeth for grinding down what we call fall-back foods - tough hard plants."

Changing weather

In comparison to the other two species, Homo erectus hominins were tall and slender. They ate things which are easier to digest, like fruits and berries.

"We also know that they were eating meat, but we aren't exactly sure how they were getting it yet. We can say that at least these early Homo erectus weren't hunting with any weaponry yet," says Baker.

"We also know that they were able to cover long distances. Which turned out lucky for them, because during their time, the climate changed in southern Africa.

Paranthropus and Australopithecus evolved in warm and humid climates and were used to that. But then the weather began to shift from warm and humid, to cool and dry," she says.

Gradually the tree-cover diminished, and grasses took their place. Eventually the forests were replaced with the African savannah grasslands of today. The cooler weather suited the more mobile and social Homo erectus better. But it meant that Paranthropus had to rely on less desirable foods.

When three species of human ancestor walked the Earth

ARIZONA STATE UNIVERSITY

IMAGE: HOMO ERECTUS CRANIUM FROM DIMOLEN, SOUTH AFRICA. view more

CREDIT: ANGELINE LEECE.

An international team, including Arizona State University researcher Gary Schwartz, have unearthed the earliest known skull of Homo erectus, the first of our ancestors to be nearly human-like in their anatomy and aspects of their behavior.

Years of painstaking excavation at the fossil-rich site of Drimolen, nestled within the Cradle of Humankind (a UNESCO World Heritage site located just 40 kilometers or around 25 miles northwest of Johannesburg in South Africa), has resulted in the recovery of several new and important fossils. The skull, attributed to Homo erectus, is securely dated to be two million years old.

Published this week in Science, the international team of nearly 30 scientists from five countries shared details of this skull -- the most ancient fossil Homo erectus known -- and other fossils from this site and discuss how these new finds are forcing us to rewrite a part of our species' evolutionary history.

The high-resolution dating of Drimolen's fossil deposits demonstrates the age of the new skull to pre-date Homo erectus specimens from other sites within and outside of Africa by at least 100,000 to 200,000 years and thus confirms an African origin for the species.

The skull, reconstructed from more than 150 separate fragments, is of an individual likely aged between three and six years old, giving scientists a rare glimpse into childhood growth and development in these early human ancestors.

Additional fossils recovered from Drimolen belong to a different species -- in fact, a different genus of ancient human altogether -- the more heavily built, robust human ancestor Paranthropus robustus, known to also occur at several nearby cave sites preserving fossils of the same geological age. A third, distinctive species, Australopithecus sediba, is known from two-million-year old deposits of an ancient cave site virtually down the road from Drimolen.

"Unlike the situation today, where we are the only human species, two million years ago our direct ancestor was not alone," said project director and lead researcher from La Trobe University in Australia, Andy Herries.

Gary Schwartz, a paleoanthropologist and research associate with ASU's Institute of Human Origins, participated in the excavations and recovery of the new cranium, and as an expert in the evolution of growth and development, is continuing his work with the research team to analyze the many infant and juvenile specimens found at the site.

"What is really exciting is the discovery that during this same narrow time slice, at just around two million years ago, there were three very different types of ancient human ancestors roaming the same small landscape," said Schwartz.

"We don't yet know whether they interacted directly, but their presence raises the possibility that these ancient fossil humans evolved strategies to divvy up the landscape and its resources in some way to enable them to live in such close proximity." Schwartz is also an Associate Professor in the School of Human Evolution and Social Change.

The ability to date Drimolen's ancient cave deposits with such a high degree of precision, using a range of different dating techniques, allowed the team to address important broader questions about human evolution in this region of Africa.

Paper coauthor Justin Adams from Monash University (Australia) is a specialist in reconstructing paleohabitats based on the animals preserved at fossil sites, said the discovery now allows us to address what role changing habitats, resources, and the unique biological adaptations of early Homo erectus may have played in the eventual extinction of Australopithecus sediba in South Africa.

"The discovery of the earliest Homo erectus marks a milestone for South African fossil heritage," says project codirector and University of Johannesburg doctoral student Stephanie Baker.

Fieldwork will continue at Drimolen, expanding the excavations to include even more ancient components of the cave and to provide a more in-depth glimpse at the forces shaping human evolution in this part of the African continent.

Archaeology News Report