How did the bushpig cross the strait? A great puzzle in African mammal biogeography solved by genomics

Africa has a huge diversity of large mammals, but their evolutionary relationships and movement across the continent over time often remain a mystery. A new scientific study sheds light on longstanding questions about the interplay between evolution and geography in one of these mammals, namely the iconic African bushpig, and helps settle a major question regarding prehistoric human activities shaping biodiversity patterns in Africa.

In the ongoing biodiversity crisis, large terrestrial animals are more threatened by extinction than any other group of organisms. The African continent holds an impressively intact large-mammal community, but there is still a lot we do not know about how these species evolved, became diverse and adapted to the changing climate and habitats. Many of these questions can be addressed by investigating the genomes and genetic variation across species.

New research, published in Nature Communications, uses genomics to answer these evolutionary questions that have been debated amongst scientists for decades: 1) how and when did bushpigs cross the Mozambique Channel and arrive at the island of Madagascar, 2) is there one or two species of bushpigs?

"This study is a result of a large international collaboration with researchers from Africa and Europe. We sequenced 67 complete bushpig genomes and by using a range of different genetic analyses, we were able to address these long-standing puzzles in African evolution and biogeography," explains one of the senior authors of the study, Associate Professor at the Department of Biology, Rasmus Heller.

Were pigs ferried across the channel during the Medieval era?

The island of Madagascar separated from the African mainland around 160 million years ago, resulting in a largely unique flora and fauna. Remarkably, the bushpig is the only large, wild terrestrial mammal species that has somehow historically crossed the 400-kilometer-wide Mozambique Channel and made it from mainland Africa to the island of Madagascar.

"Our study establishes that the bushpig was introduced to Madagascar ≈1,000-5,000 years ago from South/South-East Africa," Rasmus states. Their arrival therefore coincides with the arrival of humans to Madagascar from a region around southern Africa. Rasmus continues: "The likely explanation for this is that people transported these bushpigs across the channel. These results contradict previously published studies which dated the arrival of bushpigs ≈480,000 years ago, well before humans were present on the island." It has been suggested that some endemic Madagascar species might have arrived by rafting as passengers on floats of vegetation.

"Intriguingly, our results raise a host of new questions: was the bushpig actually brought to Madagascar as a somewhat domesticated species? There is no archaeological or other evidence of bushpig domestication ever occurring, despite them being an important source of protein for many rural communities. And who was it that transported these animals to Madagascar? Was it Bantu-speakers, Austronesian-speakers or both? These questions and others still remain to be explored," explains Renzo F. Balboa, postdoc at the Department of Biology and one of the leading authors of the study.

Does two actually equal one?

African bushpigs, which primarily are found in East/Southern Africa, and red river hogs, which are found in West/Central Africa, were considered the same species in the past, but were subsequently redefined as two species around the 1990s, largely due to their quite distinctive looks.

The red river hogs are, as the name implies red, and have long, tufted ears reminiscent of a comical Star Wars character, while eastern and southern African bushpigs are greyish and look more like our own wild boar, although with a beautiful white mane thrown in for good measure.

Biologists have been arguing for decades about whether these two forms are actually one or two different species -- a debate that is characteristic of similar scientific uncertainty surrounding many other African mammals.

"In this study, we were able to conclude that red river hogs and bushpigs have had lots of gene flow, which means they are not only able to potentially interbreed, but they have in fact done so extensively when they have met in central Africa. Furthermore, the branching of the two types in the Tree of Life is not all that old, only a few hundred thousand years, which is not long in the evolutionary scheme of things. Hence, we now know that although there are two quite different-looking lineages of bushpigs, their biological separation is incomplete, depending on how you define species," explains Laura D. Bertola, postdoc at the Department of Biology and the other leading author of the study.

Laura continues: "Genomic data can give us insights into patterns of biodiversity on a much higher resolution than previously possible. For example, we can infer detailed population structure, but also underlying processes like gene flow and selection. Gaining improved insights into patterns of biodiversity and the underlying processes that drive them, will be crucial for effective conservation measures."

Africa is a unique continent regarding the diversity of the megafauna which is still around. Studying the evolutionary history of these species can give us important insights into African biodiversity, which is highly relevant at a time where biodiversity is being lost at an alarming pace. The new findings contribute to our understanding of prehistoric relations between Africa's humans and wildlife, but also the very fundamentals about how much biodiversity there is on this amazing continent.

"This study is a great example of how involving local researchers and wildlife management authorities can lead to more robust and inclusive scientific research," co-author Vincent Muwanika, Associate Professor of Conservation Biology, at Makerere University, Uganda, concludes.

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South Africa's desert-like interior may have been more inviting to our human ancestors

Lining the Cape of South Africa and its southern coast are long chains of caves that nearly 200,000 years ago were surrounded by a lush landscape and plentiful food.

During a glacial phase that lasted between 195,000 to 123,000 years ago, these caves served as refuge to a group of humans that some researchers think were the only people to survive this ice age, called Marine Isotope Stage Six, or MIS6. And in this coastal region, a lot of archaeological research has taken place. Of less interest to archaeologists has been the interior of South Africa, which was thought to be an uninhabited, inhospitable place during at least two waves of ice ages, MIS3 and 2.

Now, a study has shown that the region might have been more fertile and temperate during these two glacial periods than previously thought, and that the region likely played host to human populations living around a series of paleolakes. The study, led by University of Michigan archaeologist Brian Stewart, provides a more comprehensive timeline of the age and stages of these lakes, and shows human fingerprints across the region. The research, funded by the National Geographic Society, is published in the journal PNAS.

"There's this perennial assumption that human population centers were always along the coast and that the interior, especially the southern interior of the Karoo Desert, were largely depopulated for long stretches of time," Stewart said. "The funny thing is that one just has to go into the interior and walk around and notice that there's archaeology everywhere."

But to flag the region as worthy of archaeological attention, the researchers needed to show that humans could have actually lived there. The research team, an international group including researchers from South Africa, the United Kingdom and France, examined a series of super flat areas of land ringed by higher ground. They showed that these regions, called "pans" in Afrikaans, are ancient lake beds, while the areas of higher elevation that encircle them are erosional landforms and sedimentary deposits left over from their ancient shorelines.

This suggests that these time periods were not as dry in this region as previously thought: there would have needed to have been sustained rainfall and humidity to keep these lakes full. The more temperate climate required to sustain lakes also meant the landscape was also able to sustain both vegetation and animals required to support human populations.

Reconstructing the paleolakes

The researchers used a variety of technologies to date and reconstruct these ancient lakes, shorelines and lake bottom deposits, and to recreate the landscape of the region.

These include radiocarbon dating and a technique called luminescence, which measures the radioactivity of tiny crystals of quartz or feldspar that haven't seen the light of day since they were covered by sediment tens of thousands of years earlier. While buried, electrons from radioactive elements common to all sediments get trapped in these crystal matrices at a constant rate. By measuring how many electrons accumulated in the sample and comparing that to the degree of background radioactivity, the researchers can predict its age.

The researchers used these techniques to date columns of sedimentary lakeshore and lake bottom deposits, called lacustrine deposits, found surrounding and within a series of three pans dotted across a region some 100,000 square miles, about the size of Texas. They also aged the shells of freshwater mollusks found scattered throughout the region and embedded within the sedimentary lake deposits.

An aquatic gastropod, Tomichia ventricosa, found at a pan called Swartkolkvloer, was embedded in a column of lacustrine deposits. Together, the deposits and shells were radiocarbon dated to two time periods: approximately 39-55 thousand years before present, and approximately 31-34 thousand years before present.

At another pan called Grootvloer, the researchers found a freshwater mollusk called Unio caffer, which required "perennial freshwater" and the presence of fish to reproduce. These shells and lacustrine deposits in this pan were dated to between approximately 20-22 thousand years before present.

The researchers were also able to predict the area of land the lakes encompassed, as well as how deep they were, based on the height of the lacustrine deposits ringing their shorelines. For example, they determined that the paleolake at Swartkolkvloer was about 83 miles square and 59 feet deep, while the paleolake at Grootvloer was likely about 17 miles square and 62 feet deep. Another pan called Alexanderfontein, some 300 miles northeast near the town of Kimberley, held a lake about 13.5 miles square and 48 feet deep.

Based on these parameters, the researchers knew the lakes would have required a climate drastically different from the one that exists in South Africa's interior today. Using a hydrological model, they determined that evaporation rates within the region were between 20% and 25% lower than what they are today, while precipitation would have been more than 200% higher at Swartkolkvloer and 88% higher at Alexanderfontein.

"In various parts of the interior, between about 60 to about 12,000 years ago, we can see that there were enduring phases of pretty large bodies of water kicking around what used to be thought of as an arid and inhospitable environment," Stewart said. "This was a period that used to be thought of as notoriously dry and freezing cold in the winter. But we've got this evidence for these large lakes existing during this time period."

The researchers say current day regions that have similar climates and rates of precipitation and evaporation are likely northern Botswana, Zambia and Zimbabwe. Based on this estimation and data found from a contemporaneous site called Equus Cave, the researchers think large grazing and browsing mammals would have thrived in this region.

A complex, prehistoric people

Scattered alongside the lakes are human artifacts such as triangular points, bladelets, weathered ostrich shells and other assemblages. Much of these are from the Middle Stone Age, which ranged from about 280,000 years ago to about 25,000 years ago, and the Later Stone Age, which lasted from 25,000 years ago right up to European contact in the 15th century.

"There's Middle Stone Age archaeology just everywhere," Stewart said. "You can't drive anywhere and open the car door and not step on it. It's astounding how much there is."

Stewart says their findings could also expand the region where archaeologists think humans became more behaviorally complex. Over the past decades, researchers have found evidence that humans living in coastal South Africa started making the leap into complex thought, showing some of the earliest signs of behavioral complexity. It was thought that both climate and nutrient stability -- including the rich omega fatty acids gleaned from seafood -- allowed humans here to become behaviorally modern.

The group's work may challenge this idea by suggesting that favorable conditions for hunter-gatherers were not confined to the coastline but probably characterized many regions as climates changed, including the interior, current-day desert.

"Ours is a basin-wide study with much more macro scale implications. It also involves some of these areas that are just inland of this coastal and mountain belt that's dominated the archaeological narratives for so long," Stewart said. "Just inland of this area is a region that has been, for a long time, portrayed as hostile, and it just simply appears not to have been the case for big chunks of time -- with the caveat that we need information on temperature depressions to understand how humans dealt with that."

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Prehistoric human migration in Southeast Asia driven by sea-level rise

An interdisciplinary team of scientists at Nanyang Technological University, Singapore (NTU, Singapore) has found that rapid sea-level rise drove early settlers in Southeast Asia to migrate during the prehistoric period, increasing the genetic diversity of the region today.

The Malay Peninsula and the islands of Sumatra, Borneo, and Java were originally part of a large landmass of rainforests and coastal mangroves in the South Asia continental shelf known as 'The Sundaland' some 26,000 years ago.

But during the last major period of global warming in Earth's history, from the Last Glacial Maximum period (approximately 26,000 -- 20,000 years ago) to the mid-50 Holocene (approximately 6,000 years ago), sea level rose 130 metres. The rise in sea level flooded and submerged half of The Sundaland, breaking land bridges and splitting the large landmass into smaller islands of the region today.

To understand the impact on humans living in The Sundaland during one of the most dramatic sea-level rises in the Earth's history, the team of NTU Singapore scientists reconstructed the history of the landmass using two different approaches: paleogeography -- the study of historical physical landscapes, and population genetics.

Lead investigator, Assistant ProfessorKim Hie Lim from NTU's Asian School of the Environment (ASE), and the Singapore Centre for Environmental Life Sciences Engineering (SCELSE) at NTU said, "Environmental changes have profound impacts on human history, driving population migration, growth, and distribution. However, less discussed is how environmental changes can shape the genetics of populations. Our work is the first reported instance to provide proof that sea-level rise changed the genetic makeup of human populations in Southeast Asia -- a legacy that continues to impact current populations."

Using data for Southeast and South Asia's sea-level history, including ancient Singapore records established by the NTU's Earth Observatory of Singapore (EOS) and ASE, the research team constructed paleogeographic maps dating from 26,000 years ago to the present.

The NTU team also used whole-genome sequence data from 59 ethnic groups, including that belonging to populations native to Southeast and South Asia from 50,000 years ago. By analysing the high-quality genome data, the team was able to infer the genetic ancestry and demographic history of the groups, including their population size and distribution.

While researchers elsewhere have studied population history based on genetics, most of them used mitochondrial DNA (genes inherited from the mother), which does not tell the full picture of individual ancestry.

By using whole-genome sequence data -- precise information of an individual's entire genetic makeup inherited from both the mother and the father -- the NTU study offers an unbiased demographic history of the indigenous populations inhabiting The Sundaland.

The whole-genome sequence data was generated by the non-profit organisation GenomeAsia 100K. Launched in 2016 and hosted by NTU, the initiative aims to better understand the genome diversity of Asian ethnicities by sequencing 100,000 genomes of people living in Asia.

Contributing author, Professor Stephan Schuster, President's Chair in Genomics at NTU's School of Biological Sciences, Research Director of SCELSE, and Scientific Chair of GenomeAsia 100K, said, "GenomeAsia 100K systematically generates maps of Asian human genetic diversity, including indigenous ethnicities who have occupied the region for a long time. Integrating those maps with paleoclimatic data allows us now to understand exactly how past climatic events have resulted in ancient human migrations, as well as their impact on today's population structure."

The research is aligned with the NTU 2025 strategy, where the University adopts more collaborative, global and interdisciplinary means of research to address Singapore's national research priorities, such as health & society.

Piecing together the story of human migration in ancient Sundaland

Combining findings from the two approaches, the scientists inferred the changes in population density from the high quality historical paleogeographic maps generated.

The map paints a picture of prehistoric human migration in The Sundaland, showing that the earliest documented instance of forced human migration was driven by sea level rise.

The scientists found that two periods of rapid sea level rise (rates of sea level rise at46 mm/year and 22 mm/year)promoted the separation of populations into smaller groups across The Sundaland, as the large landmass became split into smaller islands, forcing people to disperse.

Even as the landmass decreased after the rapid sea level rises, temperature increased from the Last Glacial Maximum, creating a favourable living environment to support human population growth. This caused population density to surge by at least eight times from the Last Glacial Maximum, especially in the Island Southeast Asian region, including Malay Peninsula, Sumatra, and Borneo.

As a result, overpopulation drove people to migrate in search of new places to settle and the people in The Sundaland later migrated back northwards, towards Mainland Southeast Asia and South Asia.

This finding is supported by evidence of migration by the ancestors of the Malaysian indigenous group (Malaysia Negrito, or commonly referred to as 'Orang Asli') into South Asian tribal groups (Austroasiatic speakers). Genetic analysis confirmed common genetic ancestry between the Malaysian and South Asian indigenous groups.

The entire process of migration therefore shaped the diverse ethnicities across Southeast and South Asian regions, as early settlers of The Sundaland interbred across different indigenous groups.

Co-author of the study, Dr Li Tanghua, Senior Research Fellow at NTU's EOS said, "Based on our findings, the Orang Asli Malaysian indigenous group can be considered the first 'casualties' of sea-level rise, or what are known as 'climate refugees' today. The population had no choice but to move from their original territory due to environmental pressures. This forced migration caused an indelible change to the genetic footprint of South Asians, contributing to one of the most ethnically diverse regions in the world."

Findings useful to understand impact of sea level rise on human ancestry

The study, published in the peer-reviewed journal Communications Biology in February, is the first to trace the impact of prehistoric sea level rise to human ancestry in Southeast Asia.

Co-author of the study, Professor Benjamin Horton, Director of NTU's EOS, said, "The study of past sea levels is essential to predicting how increasing amounts of atmospheric carbon dioxide will alter Earth's climate and raise future sea levels. These projections inform how societies can mitigate and adapt to climate change impacts."

Read more at Science Daily

Exploring the possibility of extraterrestrial life living in caves

Is there life in Martian caves?

It's a good question, but it's not the right question -- yet. An international collaboration of scientists led by NAU researcher Jut Wynne has dozens of questions we need asked and answered. Once we figure out how to study caves on the Moon, Mars and other planetary bodies, then we can return to that question.

Wynne, an assistant research professor of cave ecology, is the lead author of two related studies, both published in a special collection of papers on planetary caves by the Journal of Geophysical Research Planets. The first, "Fundamental Science and Engineering Questions in Planetary Cave Research," was done by an interdisciplinary team of 31 scientists, engineers and astronauts who produced a list of 198 questions that they, working with another 82 space and cave scientists and engineers, narrowed down to the 53 most important. Harnessing the knowledge of a considerable swath of the space science community, this work is the first study designed to identify the research and engineering priorities to advance the study of planetary caves. The team hopes their work will inform what will ultimately be needed to support robotic and human missions to a planetary cave -- namely on the Moon and/or Mars.

The second, "Planetary Caves: A Solar System View of Products and Processes," was born from the first study. Wynne realized there had been no effort to catalog planetary caves across the solar system, which is another important piece of the big-picture puzzle. He assembled another team of planetary scientists to tackle that question.

"With the necessary financial investment and institutional support, the research and technological development required to achieve these necessary advancements over the next decade are attainable," Wynne said. "We now have what I hope will become two foundational papers that will help propel planetary cave research from an armchair contemplative exercise to robots probing planetary subsurfaces."

What we know about extraterrestrial caves

There are a lot of them. Scientists have identified at least 3,545 potential caves on 11 different moons and planets throughout the solar system, including the Moon, Mars and moons of Jupiter and Saturn. Cave formation processes have even been identified on comets and asteroids. If the surrounding environment allows for access into the subsurface, that presents an opportunity for scientific discovery that's never been available before.

The discoveries in these caves could be massive. Caves may one day allow scientists to "peer into the depths" of these rocky and icy bodies, which will provide insights into how they were formed (but also can provide further insights into how Earth was formed). They could also, of course, hold secrets of life.

"Caves on many planetary surfaces represent one of the best environments to search for evidence of extinct or perhaps extant lifeforms," Wynne said. "For example, as Martian caves are sheltered from deadly surface radiation and violent windstorms, they are more likely to exhibit a more constant temperature regime compared to the surface, and some may even contain water ice. This makes caves on Mars one of the most important exploration targets in the search for life."

And it's not just finding life -- these same factors make caves good locations for astronaut shelters on Mars and the Moon when crewed missions are able to explore.

"Radiation shielding will be essential for human exploration of the Moon and Mars," said Leroy Chiao, a retired astronaut, former commander of the International Space Station and co-author of the first paper. "One possible solution is to utilize caves for this purpose. The requirements for astronaut habitats, EVA suits and equipment should take cave exploration and development into consideration, for protection from both solar and galactic cosmic radiation."

What Earth can tell us about other planets

Wynne, whose primary research is in terrestrial caves, said planetary cave research has long been a parallel research question to the earthly variety for nearly two decades. Caves support unique ecosystems that are sometimes quite divorced from the surface ecosystem in the same area. Who's to say a cave on the Moon or Mars would not be similar? So, many questions he's investigated about caves on Earth, he's wondered how it could apply on other planets.

He's not the only one making the connection. Wynne has done multiple research projects with NASA to help advance detection technologies, and his modeling of cave habitats does not much care if a cave is terrestrial or extraterrestrial. There are enough similarities in the cave environment to make reasonable predictions that will factor prominently into the selection of cave targets for exploration.

"Tellurian caves at depth are often characterized by complete darkness, a stable temperature approximating the average annual surface temperature, low to no air flow and a near-water-saturated atmosphere," he said. "The caves of other planetary bodies likely exhibit similar environmental conditions, but these will also be influenced by the surface conditions of the planetary body and the internal structure of the cave."

Keith Cowing, editor of SpaceRef.com and NASAWatch.com, said using the existing infrastructure of a planet's surface and subsurface may help humans get to other planets sooner than if we had to bring everything needed to survive with us.

"Humans have been living in caves for hundreds of thousands of years. Then they built their own when none were available," he said. "As such, it is only natural to assume that caves will offer similar utility as humanity expands to other worlds. While planet-wide terraforming may be an end goal, the use of large, pre-existing structures such as caves and lava tubes may be a more practical way to bootstrap the technology to the maturity needed to tackle the surface of an entire planet."

Where are we now?

While much of this research is forward-looking, there's also a need to consider what resources, research and support currently exist. Numerous robotic platforms and instrumentation suites are being tested, but the roadblock comes where it so often does -- the lack of funding. With sufficient support, a robotic exploration mission to a lunar or Martian cave could be possible in the next five to 10 years.

This research builds on past work to form a road map of sorts to move forward; Wynne sees it as a to-do list for that same process. The questions the scientists and engineers answered identify the tasks needed to prepare for that robotic exploration; it also looks even further ahead to the advancements needed in spacesuit technology, habitation modules and hardware that will enable humans to live and work safely underground on the Moon and Mars.

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Oldest evidence of the controlled use of fire to cook food, researchers report

A remarkable scientific discovery has been made by researchers from the Hebrew University of Jerusalem (HU), Tel Aviv University (TAU), and Bar-Ilan University (BIU), in collaboration with the Steinhardt Museum of Natural History, Oranim Academic College, the Israel Oceanographic and Limnological Research (IOLR) institution, the Natural History Museum in London, and the Johannes Gutenberg University in Mainz. A close analysis of the remains of a carp-like fish found at the Gesher Benot Ya'aqov (GBY) archaeological site in Israel shows that the fish were cooked roughly 780,000 years ago. Cooking is defined as the ability to process food by controlling the temperature at which it is heated and includes a wide range of methods. Until now, the earliest evidence of cooking dates to approximately 170,000 years ago. The question of when early man began using fire to cook food has been the subject of much scientific discussion for over a century. These findings shed new light on the matter and was published in Nature Ecology and Evolution.

The study was led by a team of researchers: Dr. Irit Zohar, a researcher at TAU's Steinhardt Museum of Natural History and curator of the Beit Margolin Biological Collections at Oranim Academic College, and HU Professor Naama Goren-Inbar, director of the excavation site. The research team also included Dr. Marion Prevost at HU's Institute of Archaeology; Prof. Nira Alperson-Afil at BIU's Department for Israel Studies and Archaeology; Dr. Jens Najorka of the Natural History Museum in London; Dr. Guy Sisma-Ventura of the Israel Oceanographic and Limnological Research Institute; Prof. Thomas Tütken of the Johannes Gutenberg University in Mainz and Prof. Israel Hershkovitz at TAU's Faculty of Medicine.

Dr. Zohar and Dr. Prevost: "This study demonstrates the huge importance of fish in the life of prehistoric humans, for their diet and economic stability. Further, by studying the fish remains found at Gesher Benot Ya'aqob we were able to reconstruct, for the first time, the fish population of the ancient Hula Lake and to show that the lake held fish species that became extinct over time. These species included giant barbs (carp like fish) that reached up to 2 meters in length. The large quantity of fish remains found at the site proves their frequent consumption by early humans, who developed special cooking techniques. These new findings demonstrate not only the importance of freshwater habitats and the fish they contained for the sustenance of prehistoric man, but also illustrate prehistoric humans' ability to control fire in order to cook food, and their understanding the benefits of cooking fish before eating it."

In the study, the researchers focused on pharyngeal teeth (used to grind up hard food such as shells) belonging to fish from the carp family. These teeth were found in large quantities at different archaeological strata at the site. By studying the structure of the crystals that form the teeth enamel (whose size increases through exposure to heat), the researchers were able to prove that the fish caught at the ancient Hula Lake, adjacent to the site, were exposed to temperatures suitable for cooking, and were not simply burned by a spontaneous fire.

Until now, evidence of the use of fire for cooking had been limited to sites that came into use much later than the GBY site -- by some 600,000 years, and ones most are associated with the emergence of our own species, homo sapiens.

Prof. Goren-Inbar added: "The fact that the cooking of fish is evident over such a long and unbroken period of settlement at the site indicates a continuous tradition of cooking food. This is another in a series of discoveries relating to the high cognitive capabilities of the Acheulian hunter-gatherers who were active in the ancient Hula Valley region. These groups were deeply familiar with their environment and the various resources it offered them. Further, it shows they had extensive knowledge of the life cycles of different plant and animal species. Gaining the skill required to cook food marks a significant evolutionary advance, as it provided an additional means for making optimal use of available food resources. It is even possible that cooking was not limited to fish, but also included various types of animals and plants."

Prof. Hershkovitz and Dr. Zohar note that the transition from eating raw food to eating cooked food had dramatic implications for human development and behavior. Eating cooked food reduces the bodily energy required to break down and digest food, allowing other physical systems to develop. It also leads to changes in the structure of the human jaw and skull. This change freed humans from the daily, intensive work of searching for and digesting raw food, providing them free time in which to develop new social and behavioral systems. Some scientists view eating fish as a milestone in the quantum leap in human cognitive evolution, providing a central catalyst for the development of the human brain. They claim that eating fish is what made us human. Even today, it is widely known that the contents of fish flesh, such as omega-3 fatty acids, zinc, iodine and more, contribute greatly to brain development.

The research team believe that the location of freshwater areas, some of them in areas that have long since dried up and become arid deserts, determined the route of the migration of early man from Africa to the Levant and beyond. Not only did these habitats provide drinking water and attracted animals to the area but catching fish in shallow water is a relatively simple and safe task with a very high nutritional reward.

The team posits that exploiting fish in freshwater habitats was the first step on prehistoric humans' route out of Africa. Early man began to eat fish around 2 million years ago but cooking fish -- as found in this study -- represented a real revolution in the Acheulian diet and is an important foundation for understanding the relationship between man, the environment, climate, and migration when attempting to reconstruct the history of early humans.

It should be noted that evidence of the use of fire at the site -- the oldest such evidence in Eurasia -- was identified first by BIU's Prof. Nira Alperson-Afil. "The use of fire is a behavior that characterizes the entire continuum of settlement at the site," she explained. "This affected the spatial organization of the site and the activity conducted there, which revolved around fireplaces." Alperson-Afil's research of fire at the site was revolutionary for its time and showed that the use of fire began hundreds of thousands of years before previously thought.

HU's Goren-Inbar added that the archaeological site of GBY documents a continuum of repeated settlement by groups of hunter-gatherers on the shores of the ancient Hula Lake which lasting tens of thousands of years. "These groups made use of the rich array of resources provided by the ancient Hula Valley and left behind a long settlement continuum with over 20 settlement strata," Goren-Inbar explained. The excavations at the site have uncovered the material culture of these ancient hominins, including flint, basalt, and limestone tools, as well as their food sources, which were characterized by a rich diversity of plant species from the lake and its shores (including fruit, nuts, and seeds) and by many species of land mammals, both medium-sized and large.

Dr. Jens Najorka of the Natural History Museum in London explained: "In this study, we used geochemical methods to identify changes in the size of the tooth enamel crystals, as a result of exposure to different cooking temperatures. When they are burnt by fire, it is easy to identify the dramatic change in the size of the enamel crystals, but it is more difficult to identify the changes caused by cooking at temperatures between 200 and 500 degrees Celsius. The experiments I conducted with Dr. Zohar allowed us to identify the changes caused by cooking at low temperatures. We do not know exactly how the fish were cooked but given the lack of evidence of exposure to high temperatures, it is clear that they were not cooked directly in fire, and were not thrown into a fire as waste or as material for burning."

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Prehistoric people created art by firelight, new research reveals

Our early ancestors probably created intricate artwork by firelight, an examination of 50 engraved stones unearthed in France has revealed.

The stones were incised with artistic designs around 15,000 years ago and have patterns of heat damage which suggests they were carved close to the flickering light of a fire, the new study has found.

The study, by researchers at the Universities of York and Durham, looked at the collection of engraved stones, known as plaquettes, which are now held in the British Museum. They are likely to have been made using stone tools by Magdalenian people, an early hunter-gatherer culture dating from between 23,000 and 14,000 years ago.

The researchers identified patterns of pink heat damage around the edges of some of the stones, providing evidence that they had been placed in close proximity to a fire.

Following their discovery, the researchers have experimented with replicating the stones themselves and used 3D models and virtual reality software to recreate the plaquettes as prehistoric artists would have seen them: under fireside light conditions and with the fresh white lines engravers would have made as they first cut into the rock thousands of years ago.

Lead author of the study, Dr Andy Needham from the Department of Archaeology at the University of York and Co-Director of the York Experimental Archaeology Research Centre said: "It has previously been assumed that the heat damage visible on some plaquettes was likely to have been caused by accident, but experiments with replica plaquettes showed the damage was more consistent with being purposefully positioned close to a fire.

"In the modern day, we might think of art as being created on a blank canvas in daylight or with a fixed light source; but we now know that people 15,000 years ago were creating art around a fire at night, with flickering shapes and shadows."

Working under these conditions would have had a dramatic effect on the way prehistoric people experienced the creation of art, the researchers say. It may have activated an evolutionary capacity designed to protect us from predators called "Pareidolia," where perception imposes a meaningful interpretation such as the form of an animal, a face or a pattern where there is none.

Dr Needham added: "Creating art by firelight would have been a very visceral experience, activating different parts of the human brain. We know that flickering shadows and light enhance our evolutionary capacity to see forms and faces in inanimate objects and this might help explain why it's common to see plaquette designs that have used or integrated natural features in the rock to draw animals or artistic forms."

The Magdalenian era saw a flourishing of early art, from cave art and the decoration of tools and weapons to the engraving of stones and bones.

Co-author of the study, PhD student Izzy Wisher from the Department of Archaeology at the University of Durham, said: "During the Magdalenian period conditions were very cold and the landscape was more exposed. While people were well-adapted to the cold, wearing warm clothing made from animal hides and fur, fire was still really important for keeping warm. Our findings reinforce the theory that the warm glow of the fire would have made it the hub of the community for social gatherings, telling stories and making art.

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Collectors in the prehistoric world recycled old stone tools to preserve the memory of their ancestors

A first-of-its-kind study at Tel Aviv University asks what drove prehistoric humans to collect and recycle flint tools that had been made, used, and discarded by their predecessors. After examining flint tools from one layer at the 500,000-year-old prehistoric site of Revadim in the south of Israel's Coastal Plain, the researchers propose a novel explanation: prehistoric humans, just like us, were collectors by nature and culture. The study suggests that they had an emotional urge to collect old human-made artefacts, mostly as a means for preserving the memory of their ancestors and maintaining their connectedness with place and time.

The study was led by PhD student Bar Efrati and Prof. Ran Barkai of the Jacob M. Alkow Department of Archaeology and Ancient Near Eastern Cultures at TAU's Entin Faculty of Humanities, in collaboration with Dr. Flavia Venditti from the University of Tubingen in Germany and Prof. Stella Nunziante Cesaro from the Sapienza University of Rome, Italy. The paper appeared in the journal Scientific Reports, published by Nature.

Bar Efrati explains that stone tools with two lifecycles have been found at prehistoric sites all over the world, but the phenomenon has never been thoroughly investigated. In the current study the researchers focused on a specific layer at Revadim -- a large, open-air, multi-layered site in the south of Israel's Coastal Plain, dated to about 500,000 years ago. The rich findings at Revadim suggest that this was a popular spot in the prehistoric landscape, revisited over and over again by early humans drawn by an abundance of wildlife, including elephants. Moreover, the area is rich with good-quality flint, and most tools found at Revadim were in fact made of fresh flint.

Bar Efrati: "The big question is: Why did they do it? Why did prehistoric humans collect and recycle actual tools originally produced, used, and discarded by their predecessors, many years earlier? Scarcity of raw materials was clearly not the reason at Revadim, where good-quality flint is easy to come by. Nor was the motivation merely functional, since the recycled tools were neither unusual in form nor uniquely suitable for any specific use."

The key to identifying the recycled tools and understanding their history is the patina -- a chemical coating which forms on flint when it is exposed to the elements for a long period of time. Thus, a discarded flint tool that lay on the ground for decades or centuries accumulated an easily identifiable layer of patina, which is different in both color and texture from the scars of a second cycle of processing that exposed the original color and texture of flint.

In the current study, 49 flint tools with two lifecycles were examined. Produced and used in their first lifecycle, these tools were abandoned, and years later, after accumulating a layer of patina, they were collected, reworked, and used again. The individuals who recycled each tool removed the patina, exposing fresh flint, and shaped a new active edge. Both edges, the old and the new, were examined by the researchers under two kinds of microscopes, and via various chemical analyses, in search of use-wear marks and/or organic residues. In the case of 28 tools, use-wear marks were found on the old and/or new edges, and in 13 tools, organic residues were detected, evidence of contact with animal bones or fat.

Surprisingly, the tools had been used for very different purposes in their two lifecycles -- the older edges primarily for cutting, and the newer edges for scraping (processing soft materials like leather and bone). Another baffling discovery: in their second lifecycle the tools were reshaped in a very specific and minimal manner, preserving the original form of the tool, including its patina, and only slightly modifying the active edge.

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Early modern human from Southeast Asia adapted to a rainforest environment

Traditional assumptions have often seen tropical rainforests as a barrier to early Homo sapiens. However, growing proof shows that humans adapted to and lived in tropical rainforest habitats of Southeast Asia. Some researchers also suggest that, in the past, other human species, like Homo erectus and Homo floresiensis, became extinct because they could not adapt to this environment as our species did. However, we know very little about the ecological adaptation of fossil humans, including what they were eating.

Zinc isotopes reveal what kind of food was primarily eaten

In this study, researchers analysed the zinc stable isotope ratios from animal and human teeth from two sites in the Huà Pan Province of Laos: Tam Pà Ling and the nearby site of Nam Lot. "The site of Tam Pà Ling is particularly important for palaeoanthropology and archaeology of Southeast Asia because it holds the oldest and most abundant fossil record of our species in this region," explains Fabrice Demeter, researcher at the University of Copenhagen. However, there is little archaeological evidence, like stone tools, hearth features, plant remains, cut marks on bones, in Tam Pà Ling: only teeth and bones. This makes isotopic approaches the only way to gain insight into past dietary reliance.

Nitrogen isotope analysis, in particular, can help scientists learn if past humans were eating animals or plants. However, the collagen in bones and teeth needed to do these analyses is not easily conservable. In tropical regions like the one at Tam Pà Ling this problem is even more acute. "New methods -- such as zinc isotope analysis of enamel -- can now overcome these limitations and allow us to investigate teeth from regions and periods we could not study before," says study leader Thomas Tütken, professor at the Johannes Gutenberg University's Institute of Geosciences. "With zinc stable isotope ratios, we can now study Tam Pà Ling and learn what kind of food our earliest ancestors in this region were eating."

First study that reveals the whole diet of fossil humans from Southeast Asia

The fossil human studied in this research dates from the Late Pleistocene, more precisely from 46,000 to 63,000 years ago. With it, various mammals from both sites, including water buffaloes, rhinos, wild boars, deer, bears, orangutans, macaques, and leopards, were also analysed. All these different animals show various eating behaviours, making for an ideal background to determine what exactly humans were eating at the time. The more diverse the animal remains found at a particular site are, the more information the researchers can use to understand the diet of prehistoric humans.

When we compare the zinc isotope values from the fossil Homo sapiens of Tam Pà Ling to that of the animals, it strongly suggests that its diet contained both plants and animals. This omnivorous diet also differs from most nitrogen isotope data of humans in other regions of the world for that time period, where a meat-rich diet is almost consistently discerned. "Another kind of analysis performed in this study -- stable carbon isotopes analysis -- indicates that the food consumed came strictly from forested environments," says Élise Dufour, researcher at the National Natural History Museum of Paris. "The results are the oldest direct evidence for subsistence strategies for Late Pleistocene humans in tropical rainforests."

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