Oldest fossil human footprints in North America confirmed

The 2021 results began a global conversation that sparked public imagination and incited dissenting commentary throughout the scientific community as to the accuracy of the ages.

"The immediate reaction in some circles of the archeological community was that the accuracy of our dating was insufficient to make the extraordinary claim that humans were present in North America during the Last Glacial Maximum. But our targeted methodology in this current research really paid off," said Jeff Pigati, USGS research geologist and co-lead author of a newly published study that confirms the age of the White Sands footprints.

The controversy centered on the accuracy of the original ages, which were obtained by radiocarbon dating. The age of the White Sands footprints was initially determined by dating seeds of the common aquatic plant Ruppia cirrhosa that were found in the fossilized impressions. But aquatic plants can acquire carbon from dissolved carbon atoms in the water rather than ambient air, which can potentially cause the measured ages to be too old.

"Even as the original work was being published, we were forging ahead to test our results with multiple lines of evidence," said Kathleen Springer, USGS research geologist and co-lead author on the current Science paper. "We were confident in our original ages, as well as the strong geologic, hydrologic, and stratigraphic evidence, but we knew that independent chronologic control was critical."

For their follow-up study, the researchers focused on radiocarbon dating of conifer pollen, because it comes from terrestrial plants and therefore avoids potential issues that arise when dating aquatic plants like Ruppia. The researchers used painstaking procedures to isolate approximately 75,000 pollen grains for each sample they dated. Importantly, the pollen samples were collected from the exact same layers as the original seeds, so a direct comparison could be made. In each case, the pollen age was statistically identical to the corresponding seed age.

"Pollen samples also helped us understand the broader environmental context at the time the footprints were made," said David Wahl, USGS research geographer and a co-author on the current Science article. "The pollen in the samples came from plants typically found in cold and wet glacial conditions, in stark contrast with pollen from the modern playa which reflects the desert vegetation found there today."

In addition to the pollen samples, the team used a different type of dating called optically stimulated luminescence, which dates the last time quartz grains were exposed to sunlight. Using this method, they found that quartz samples collected within the footprint-bearing layers had a minimum age of ~21,500 years, providing further support to the radiocarbon results.

With three separate lines of evidence pointing to the same approximate age, it is highly unlikely that they are all incorrect or biased and, taken together, provide strong support for the 21,000 to 23,000-year age range for the footprints.

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Nose shape gene inherited from Neanderthals

Humans inherited genetic material from Neanderthals that affects the shape of our noses, finds a new study led by UCL researchers.

The new Communications Biology study finds that a particular gene, which leads to a taller nose (from top to bottom), may have been the product of natural selection as ancient humans adapted to colder climates after leaving Africa.

Co-corresponding author Dr Kaustubh Adhikari (UCL Genetics, Evolution & Environment and The Open University) said: "In the last 15 years, since the Neanderthal genome has been sequenced, we have been able to learn that our own ancestors apparently interbred with Neanderthals, leaving us with little bits of their DNA.

"Here, we find that some DNA inherited from Neanderthals influences the shape of our faces. This could have been helpful to our ancestors, as it has been passed down for thousands of generations."

The study used data from more than 6,000 volunteers across Latin America, of mixed European, Native American and African ancestry, who are part of the UCL-led CANDELA study, which recruited from Brazil, Colombia, Chile, Mexico and Peru. The researchers compared genetic information from the participants to photographs of their faces -- specifically looking at distances between points on their faces, such as the tip of the nose or the edge of the lips -- to see how different facial traits were associated with the presence of different genetic markers.

The researchers newly identified 33 genome regions associated with face shape, 26 of which they were able to replicate in comparisons with data from other ethnicities using participants in east Asia, Europe, or Africa.

In one genome region in particular, called ATF3, the researchers found that many people in their study with Native American ancestry (as well as others with east Asian ancestry from another cohort) had genetic material in this gene that was inherited from the Neanderthals, contributing to increased nasal height. They also found that this gene region has signs of natural selection, suggesting that it conferred an advantage for those carrying the genetic material.

First author Dr Qing Li (Fudan University) said: "It has long been speculated that the shape of our noses is determined by natural selection; as our noses can help us to regulate the temperature and humidity of the air we breathe in, different shaped noses may be better suited to different climates that our ancestors lived in. The gene we have identified here may have been inherited from Neanderthals to help humans adapt to colder climates as our ancestors moved out of Africa."

Co-corresponding author Professor Andres Ruiz-Linares (Fudan University, UCL Genetics, Evolution & Environment, and Aix-Marseille University) added: "Most genetic studies of human diversity have investigated the genes of Europeans; our study's diverse sample of Latin American participants broadens the reach of genetic study findings, helping us to better understand the genetics of all humans."

The finding is the second discovery of DNA from archaic humans, distinct from Homo sapiens, affecting our face shape. The same team discovered in a 2021 paper that a gene influencing lip shape was inherited from the ancient Denisovans.

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Ancient DNA analysis sheds light on the early peopling of South America

The Americas were the last continent to be inhabited by humans. An increasing body of archaeological and genomic evidence has hinted to a complex settlement process. This is especially true for South America, where unexpected ancestral signals have raised perplexing scenarios for the early migrations into different regions of the continent.

Many unanswered questions still persist, such as whether the first humans migrated south along the Pacific coast or by some other route. While there is archaeological evidence for a north-to-south migration during the initial peopling of the Americas by ancient Indigenous peoples, where these ancient humans went after they arrived has remained elusive.

Using DNA from two ancient human individuals unearthed in two different archaeological sites in northeast Brazil -- Pedra do Tubarão and Alcobaça -- and powerful algorithms and genomic analyses, Florida Atlantic University researchers in collaboration with Emory University have unraveled the deep demographic history of South America at the regional level with some unexpected and surprising results.

Not only do researchers provide new genetic evidence supporting existing archaeological data of the north-to-south migration toward South America, they also have discovered migrations in the opposite direction along the Atlantic coast -- for the first time. The work provides the most complete genetic evidence to date for complex ancient Central and South American migration routes.

Among the key findings, researchers also have discovered evidence of Neanderthal ancestry within the genomes of ancient individuals from South America. Neanderthals are an extinct population of archaic humans that ranged across Eurasia during the Lower and Middle Paleolithic.

Results of the study, published in the journal Proceedings of the Royal Society B. (Biological Sciences), suggest that human movements closer to the Atlantic coast eventually linked ancient Uruguay and Panama in a south-to-north migration route -- 5,277 kilometers (3,270 miles) apart. This novel migration pattern is estimated to have occurred approximately 1,000 years ago based on the ages of the ancient individuals.

Findings show a distinct relationship among ancient genomes from northeast Brazil, Lagoa Santa (southeast Brazil), Uruguay and Panama. This new model reveals that the settlement of the Atlantic coast occurred only after the peopling of most of the Pacific coast and Andes.

"Our study provides key genomic evidence for ancient migration events at the regional scale along South America's Atlantic coast," said Michael DeGiorgio, Ph.D., co-corresponding author who specializes in human, evolutionary, and computational genomics and is an associate professor in the Department of Electrical Engineering and Computer Science within FAU's College of Engineering and Computer Science. "These regional events likely derived from migratory waves involving the initial Indigenous peoples of South America near the Pacific coast."

Researchers also found strong Australasian (Australia and Papua New Guinea) genetic signals in an ancient genome from Panama.

"There is an entire Pacific Ocean between Australasia and the Americas, and we still don't know how these ancestral genomic signals appeared in Central and South America without leaving traces in North America," said Andre Luiz Campelo dos Santos, Ph.D., first author, an archaeologist and a postdoctoral fellow in FAU's Department of Electrical Engineering and Computer Science.

To further add to the existing complexity, researchers also detected greater Denisovan than Neanderthal ancestry in ancient Uruguay and Panama individuals. Denisovans are a group of extinct humans first identified from DNA sequences from the tip of finger bone discovered around 2008.

"It's phenomenal that Denisovan ancestry made it all the way to South America," says John Lindo, Ph.D., a co-corresponding author of the article who specializes in ancient DNA analysis and is an assistant professor in the Department of Anthropology at Emory University. "The admixture must have occurred a long time before, perhaps 40,000 years ago. The fact that the Denisovan lineage persisted and its genetic signal made it into an ancient individual from Uruguay that is only 1,500 years old suggests that it was a large admixture event between a population of humans and Denisovans."

Previously at the Federal University of Pernambuco in Recife, Brazil, dos Santos and colleagues uncovered the remains of the two ancient humans from northeast Brazil, which date back to at least 1,000 years before present, and sent them to Lindo for DNA extraction and subsequent genomic sequencing and analyses. Raw data were then sent to FAU for computational analysis of the whole genome sequences from northeast Brazil.

Researchers compared the two newly sequenced ancient whole genomes from northeast Brazil with present-day worldwide genomes and other ancient whole genomes from the Americas. As of the publication date of the article, Lindo says that only a dozen or so ancient whole genomes from South America have been sequenced and published, in contrast to hundreds from Europe.

Apart from the occurrence of mass burials in the sites that yielded the samples from northeast Brazil, Uruguay, southeast Brazil and Panama, there is no other evidence in the archaeological record that indicate shared cultural features among them. Importantly, the analyzed ancient individuals from southeast Brazil are about 9,000 years older than those from northeast Brazil, Uruguay and Panama, enough time for expected and noticeable cultural divergence. Moreover, northeast Brazil, Uruguay and Panama, though more similar in age, are located thousands of kilometers apart from each other.

"This groundbreaking research involved many different fields from archaeology to biological sciences to genomics and data science," said Stella Batalama, Ph.D., dean, FAU College of Engineering and Computer Science. "Our scientists at Florida Atlantic University in collaboration with Emory University have helped to shed light on an important piece of the Americas puzzle, which could not have been solved without powerful genomic and computational tools and analysis."

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How DNA is preserved in archaeological sediments for thousands of years

Sediments in which archaeological finds are embedded have long been regarded by most archaeologists as unimportant by-products of excavations. However, in recent years it has been shown that sediments can contain ancient biomolecules, including DNA. "The retrieval of ancient human and faunal DNA from sediments offers exciting new opportunities to investigate the geographical and temporal distribution of ancient humans and other organisms at sites where their skeletal remains are rare or absent," says Matthias Meyer, senior author of the study and researcher at the Max Planck Institute for Evolutionary Anthropology in Leipzig.

To investigate the origin of DNA in the sediment, Max Planck researchers teamed up with an international group of geoarchaeologists -- archaeologists who apply geological techniques to reconstruct the formation of sediment and sites -- to study DNA preservation in sediment at a microscopic scale. They used undisturbed blocks of sediment that had been previously removed from archaeological sites and soaked in synthetic plastic-like (polyester) resin. The hardened blocks were taken to the laboratory and sliced in sections for microscopic imaging and genetic analysis.

The researchers successfully extracted DNA from a collection of blocks of sediment prepared as long as 40 years ago, from sites in Africa, Asia, Europe and North America. "The fact that these blocks are an excellent source of ancient DNA -- including that originating from hominins -- despite often decades of storage in plastic, provides access to a vast untapped repository of genetic information. The study opens up a new era of ancient DNA studies that will revisit samples stored in labs, allowing for analysis of sites that have long since been back-filled, which is especially important given travel restriction and site inaccessibility in a pandemic world," says Mike Morley from Flinders University in Australia who led some of the geoarchaeological analyses.

Abundance of micro remains in the sediment matrix

The scientists used blocks of sediment from Denisova Cave, a site located in the Altai Mountains in South Central Siberia where ancient DNA from Neanderthals, Denisovans and modern humans has been retrieved, and showed that small organic particles yielded more DNA than sediment sampled randomly. "It clearly shows that the high success rate of ancient mammalian DNA retrieval from Denisova Cave sediments comes from the abundance of micro remains in the sediment matrix rather than from free extracellular DNA from feces, bodily fluids or decomposing cellular tissue potentially adsorbed onto mineral grains," says Vera Aldeias, co-author of the study and researcher at the University of Algarve in Portugal. "This study is a big step closer to understand precisely where and under what conditions ancient DNA is preserved in sediments," says Morley.

The approach described in the study allows highly localized micro-scalesampling of sediment for DNA analyses and shows that ancient DNA (aDNA) is not uniformly distributed in the sediment; and that specific sediment features are more conducive to ancient DNA preservation than others. "Linking sediment aDNA to the archaeological micro-context means that we can also address the possibility of physical movement of aDNA between sedimentary deposits," says Susan Mentzer a researcher at the Senckenberg Centre for Human Evolution and Palaeoenvironment (Germany).

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Prehistoric humans rarely mated with their cousins

The researchers re-analyzed previously published DNA data from ancient humans that lived during the last 45,000 years to find out how closely related their parents were. The results surprising: Ancient humans rarely chose their cousins as mates. In a global dataset of 1,785 individuals only 54, that is, about three percent, show the typical signs of their parents being cousins. Those 54 did not cluster in space or time, showing that cousin matings were sporadic events in the studied ancient populations. Notably, even for hunter-gatherers who lived more than 10,000 years ago, unions between cousins were the exception.

To analyze such a large dataset, the researchers developed a new computational tool to screen ancient DNA for parental relatedness. It detects long stretches of DNA that are identical in the two DNA copies, one inherited from the mother and one from the father. The closer the parents are related, the longer and more abundant such identical segments are. For modern DNA data, computational methods can identify these stretches with ease. However, the quality of DNA from bones that are thousands of years old is, in most cases, too low to apply these methods. Thus, the new method fills the gaps in the ancient genomes by leveraging modern high-quality DNA data. "By applying this new technique we could screen more than ten times as many ancient genomes than previously possible," says Harald Ringbauer from MPI-EVA, the lead researcher of the study.

Beyond identifying matings of close kin, the new method also allowed the researchers to study background relatedness. Such relatedness originates from the typically many unknown distant relationships within small populations. As a key result, the researchers found a substantial demographic impact of the technological innovation of agriculture. This was always followed by a marked decay in background parental relatedness, indicative of increasing population sizes. By analyzing time transects of more than a dozen geographic regions across the globe, the researchers expanded upon previous evidence that population sizes increased in societies practicing farming compared to hunter-gatherer subsistence strategies.

The new method to screen ancient DNA for parental relatedness gives researchers a versatile new tool. Looking forward, the field of ancient DNA is quickly developing, with more and more ancient genomes being produced every year. By elucidating mating choices as well as the dynamics of past population sizes, the new method will allow researchers to shed more light on the lives of our ancestors.

From Science Daily

'Dragon man' fossil may replace Neanderthals as our closest relative

A near-perfectly preserved ancient human fossil known as the Harbin cranium sits in the Geoscience Museum in Hebei GEO University. The largest of known Homo skulls, scientists now say this skull represents a newly discovered human species named Homo longi or "Dragon Man." Their findings, appearing in three papers publishing June 25 in the journal The Innovation, suggest that the Homo longi lineage may be our closest relatives -- and has the potential to reshape our understanding of human evolution.

"The Harbin fossil is one of the most complete human cranial fossils in the world," says author Qiang Ji, a professor of paleontology of Hebei GEO University. "This fossil preserved many morphological details that are critical for understanding the evolution of the Homo genus and the origin of Homo sapiens."

The cranium was reportedly discovered in the 1930s in Harbin City of the Heilongjiang province of China. The massive skull could hold a brain comparable in size to modern humans' but had larger, almost square eye sockets, thick brow ridges, a wide mouth, and oversized teeth. "While it shows typical archaic human features, the Harbin cranium presents a mosaic combination of primitive and derived characters setting itself apart from all the other previously-named Homo species," says Ji, leading to its new species designation of Homo longi.

Scientists believe the cranium came from a male individual, approximately 50 years old, living in a forested, floodplain environment as part of a small community. "Like Homo sapiens, they hunted mammals and birds, and gathered fruits and vegetables, and perhaps even caught fish," remarks author Xijun Ni, a professor of primatology and paleoanthropology at the Chinese Academy of Sciences and Hebei GEO University. Given that the Harbin individual was likely very large in size as well as the location where the skull was found, researchers suggest H. longi may have been adapted for harsh environments, allowing them to disperse throughout Asia.

Using a series of geochemical analyses, Ji, Ni, and their team dated the Harbin fossil to at least 146,000 years, placing it in the Middle Pleistocene, a dynamic era of human species migration. They hypothesize that H. longi and H. sapiens could have encountered each other during this era.

"We see multiple evolutionary lineages of Homo species and populations co-existing in Asia, Africa, and Europe during that time. So, if Homo sapiens indeed got to East Asia that early, they could have a chance to interact with H. longi, and since we don't know when the Harbin group disappeared, there could have been later encounters as well," says author Chris Stringer, a paleoanthropologist at the Nature History Museum in London.

Looking farther back in time, the researchers also find that Homo longi is one of our closest hominin relatives, even more closely related to us than Neanderthals. "It is widely believed that the Neanderthal belongs to an extinct lineage that is the closest relative of our own species. However, our discovery suggests that the new lineage we identified that includes Homo longi is the actual sister group of H. sapiens," says Ni.

Their reconstruction of the human tree of life also suggests that the common ancestor we share with Neanderthals existed even further back in time. "The divergence time between H. sapiens and the Neanderthals may be even deeper in evolutionary history than generally believed, over one million years," says Ni. If true, we likely diverged from Neanderthals roughly 400,000 years earlier than scientists had thought.

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Earliest evidence of humans changing ecosystems with fire

Mastery of fire has given humans dominance over the natural world. A Yale-led study provides the earliest evidence to date of ancient humans significantly altering entire ecosystems with flames.

The study, published on May 5 in the journal Science Advances, combines archaeological evidence -- dense clusters of stone artifacts dating as far back as 92,000 years ago -- with paleoenvironmental data on the northern shores of Lake Malawi in eastern Africa to document that early humans were ecosystem engineers. They used fire in a way that prevented regrowth of the region's forests, creating a sprawling bushland that exists today.

Yale paleoanthropologist Jessica Thompson describes the earliest evidence of humans altering their ecosystem with fire in this video.

"This is the earliest evidence I have seen of humans fundamentally transforming their ecosystem with fire," said Jessica Thompson, assistant professor of anthropology in the Faculty of Arts and Sciences and the paper's lead author. "It suggests that by the Late Pleistocene, humans were learning to use fire in truly novel ways. In this case, their burning caused replacement of the region's forests with the open woodlands you see today."

Thompson authored the study with 27 colleagues from institutions in the United States, Africa, Europe, Asia, and Australia. Thompson led the archaeological work in collaboration with the Malawi Department of Museums and Monuments; David Wright of the University of Oslo, who led efforts to date the study's archaeological sites; and Sarah Ivory of Penn State, who led the paleoenvironmental analyses.

The artifacts examined by the researchers are of the type produced across Africa in the Middle Stone Age, a period dating back at least 315,000 years. The earliest modern humans made their appearance during this period, with the African archaeological record showing significant advances in cognitive and social complexity.

Thompson and Wright logged several field seasons of archaeological work in the region before a conversation with Ivory helped them make sense of the patterns they observed in their data. The researchers discovered that the regional archaeological record, its ecological changes, and the development of alluvial fans near Lake Malawi -- an accumulation of sediment eroded from the region's highland -- dated to the same period of origin, suggesting that they were connected.

Lake Malawi's water levels have fluctuated drastically over the ages. During the lake's driest periods, the last of which ended about 85,000 years ago, it diminished into two small, saline bodies of water. The lake recovered from these arid stretches and its levels have remained high ever since, according to the study.

The archaeological data were collected from more than 100 pits excavated across hundreds of kilometers of the alluvial fan that developed during this time of steady lake levels. The paleoenvironmental data are based on counts of pollen and charcoal that settled to the floor of the lakebed and were later recovered in a long sediment core drilled from a modified barge.

According to the researchers, the data revealed that a spike in charcoal accumulation occurred shortly before the flattening of the region's species richness -- the number of distinct species inhabiting it. Despite the consistently high lake levels, which imply greater stability in the ecosystem, the species richness went flat following the last arid period based on information from fossilized pollen sampled from the lakebed, the study found. This was unexpected because over previous climate cycles, rainy environments had produced forests that provide rich habitat for an abundance of species, Ivory explained.

"The pollen that we see in this most recent period of stable climate is very different than before," she said. "Specifically, trees that indicate dense, structurally complex forest canopies are no longer common and are replaced by pollen from plants that deal well with frequent fire and disturbance."

The increase in archaeological sites after the last arid period, paired with the spike in charcoal and absence of forest, suggests that people were manipulating the ecosystem with fire, the researchers conclude. The scale of their environmental impact over the long term is something typically associated with farmers and herders, rather than hunter-gatherers. This suggests early ecological manipulation on par with modern people and may also explain why the archaeological record formed.

The burning paired with climate-driven changes created the conditions that allowed for preservation of millions of artifacts in the region, the researchers explained. "Dirt rolls downhill unless there is something to stop it," Wright said. "Take the trees away, and when it rains, there is a lot of dirt moving downhill in this environment."

Previous transitions from dry to wet conditions in the region didn't yield a similar alluvial fan and were not preceded by the same charcoal spike, the researchers noted.

It's not clear why people were burning the landscape, Thompson said. It's possible that they were experimenting with controlled burns to produce mosaic habitats conducive to hunting and gathering, a behavior documented among hunter-gatherers. It could be that their fires burned out of control, or that there were simply a lot of people burning fuel in their environment that provided for warmth, cooking, or socialization, she explained.

"One way or another, it's caused by human activity," she said. "It shows early people, over a long period of time, took control over their environment rather than being controlled by it. They changed entire landscapes, and for better or for worse that relationship with our environments continues today."

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How a single gene alteration may have separated modern humans from predecessors

 As a professor of pediatrics and cellular and molecular medicine at University of California San Diego School of Medicine, Alysson R. Muotri, PhD, has long studied how the brain develops and what goes wrong in neurological disorders. For almost as long, he has also been curious about the evolution of the human brain -- what changed that makes us so different from preceding Neanderthals and Denisovans, our closest evolutionary relatives, now extinct?

Evolutionary studies rely heavily on two tools -- genetics and fossil analysis -- to explore how a species changes over time. But neither approach can reveal much about brain development and function because brains do not fossilize, Muotri said. There is no physical record to study.

So Muotri decided to try stem cells, a tool not often applied in evolutionary reconstructions. Stem cells, the self-renewing precursors of other cell types, can be used to build brain organoids -- "mini brains" in a laboratory dish. Muotri and colleagues have pioneered the use of stem cells to compare humans to other primates, such as chimpanzees and bonobos, but until now a comparison with extinct species was not thought possible.

In a study published February 11, 2021 in Science, Muotri's team catalogued the differences between the genomes of diverse modern human populations and the Neanderthals and Denisovans, who lived during the Pleistocene Epoch, approximately 2.6 million to 11,700 years ago. Mimicking an alteration they found in one gene, the researchers used stem cells to engineer "Neanderthal-ized" brain organoids.

"It's fascinating to see that a single base-pair alteration in human DNA can change how the brain is wired," said Muotri, senior author of the study and director of the UC San Diego Stem Cell Program and a member of the Sanford Consortium for Regenerative Medicine. "We don't know exactly how and when in our evolutionary history that change occurred. But it seems to be significant, and could help explain some of our modern capabilities in social behavior, language, adaptation, creativity and use of technology."

The team initially found 61 genes that differed between modern humans and our extinct relatives. One of these altered genes -- NOVA1 -- caught Muotri's attention because it's a master gene regulator, influencing many other genes during early brain development. The researchers used CRISPR gene editing to engineer modern human stem cells with the Neanderthal-like mutation in NOVA1. Then they coaxed the stem cells into forming brain cells and ultimately Neanderthal-ized brain organoids.

Brain organoids are little clusters of brain cells formed by stem cells, but they aren't exactly brains (for one, they lack connections to other organ systems, such as blood vessels). Yet organoids are useful models for studying genetics, disease development and responses to infections and therapeutic drugs. Muotri's team has even optimized the brain organoid-building process to achieve organized electrical oscillatory waves similar to those produced by the human brain.

The Neanderthal-ized brain organoids looked very different than modern human brain organoids, even to the naked eye. They had a distinctly different shape. Peering deeper, the team found that modern and Neanderthal-ized brain organoids also differ in the way their cells proliferate and how their synapses -- the connections between neurons -- form. Even the proteins involved in synapses differed. And electrical impulses displayed higher activity at earlier stages, but didn't synchronize in networks in Neanderthal-ized brain organoids.

According to Muotri, the neural network changes in Neanderthal-ized brain organoids parallel the way newborn non-human primates acquire new abilities more rapidly than human newborns.

"This study focused on only one gene that differed between modern humans and our extinct relatives. Next we want to take a look at the other 60 genes, and what happens when each, or a combination of two or more, are altered," Muotri said.

"We're looking forward to this new combination of stem cell biology, neuroscience and paleogenomics. The ability to apply the comparative approach of modern humans to other extinct hominins, such as Neanderthals and Denisovans, using brain organoids carrying ancestral genetic variants is an entirely new field of study."

To continue this work, Muotri has teamed up with Katerina Semendeferi, professor of anthropology at UC San Diego and study co-author, to co-direct the new UC San Diego Archealization Center, or ArchC.

Read more at Science Daily

On the origins of money: Ancient European hoards full of standardized bronze objects

 In the Early Bronze Age of Europe, ancient people used bronze objects as an early form of money, even going so far as to standardize the shape and weight of their currency, according to a study published January 20, 2020 in the open-access journal PLOS ONE by Maikel H. G. Kuijpers and Cătălin N. Popa of Leiden University, Netherlands.

Money is an important feature of modern human society. One key feature of money is standardization, but this can be difficult to identify in the archaeological record since ancient people had inexact forms of measurement compared with today. In this study, the authors assessed possible money from the Early Bronze Age of Central Europe, comparing the objects based on their perceived -- if not precise -- similarity.

The objects studied were made of bronze in shapes described as rings, ribs, and axe blades. The authors examined more than 5,000 such objects from more than 100 ancient hoards. They statistically compared the objects' weights using a psychology principle known as the Weber fraction, which quantifies the concept that, if objects are similar enough in mass, a human being weighing them by hand can't tell the difference.

They found that even though the objects' weights varied, around 70% of the rings were similar enough to have been indistinguishable by hand (averaging about 195 grams), as were subsets of the ribs and axe blades.

The authors suggest that this consistent similarity in shape and weight, along with the fact that these objects often occurred in hoards, are signs of their use as an early form of standardized currency. Later, in the Middle Bronze Age of Europe, more precise weighing tools appear in the archaeological record along with an increase in scrap bronze, pointing to a developed system of weighing.

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Largest-ever ancient-DNA study illuminates millennia of South and Central Asian prehistory

The largest-ever study of ancient human DNA, along with the first genome of an individual from the ancient Indus Valley Civilization, reveal in unprecedented detail the shifting ancestry of Central and South Asian populations over time.

The research, published online Sept. 5 in a pair of papers in Science and Cell, also answers longstanding questions about the origins of farming and the source of Indo-European languages in South and Central Asia.

Geneticists, archaeologists and anthropologists from North America, Europe, Central Asia and South Asia analyzed the genomes of 524 never before-studied ancient individuals. The work increased the worldwide total of published ancient genomes by about 25 percent.

By comparing these genomes to one another and to previously sequenced genomes, and by putting the information into context alongside archaeological, linguistic and other records, the researchers filled in many of the key details about who lived in various parts of this region from the Mesolithic Era (about 12,000 years ago) to the Iron Age (until around 2,000 years ago) and how they relate to the people who live there today.

"With this many samples, we can detect subtle interactions between populations as well as outliers within populations, something that has only become possible in the last couple of years through technological advances," said David Reich, co-senior author of both papers and professor of genetics in the Blavatnik Institute at Harvard Medical School.

"These studies speak to two of the most profound cultural transformations in ancient Eurasia -- the transition from hunting and gathering to farming and the spread of Indo-European languages, which are spoken today from the British Isles to South Asia -- along with the movement of people," said Vagheesh Narasimhan, co-first author of both papers and a postdoctoral fellow in the Reich lab. "The studies are particularly significant because Central and South Asia are such understudied parts of the world."

"One of the most exciting aspects of this study is the way it integrates genetics with archaeology and linguistics," said Ron Pinhasi of the University of Vienna, co-senior author of the Science paper. "The new results emerged after combining data, methods and perspectives from diverse academic disciplines, an integrative approach that provides much more information about the past than any one of these disciplines could alone."

"In addition, the introduction of new sampling methodologies allowed us to minimize damage to skeletons while maximizing the chance of obtaining genetic data from regions where DNA preservation is often poor," Pinhasi added.

Language key

Indo-European languages -- including Hindi/Urdu, Bengali, Punjabi, Persian, Russian, English, Spanish, Gaelic and more than 400 others -- make up the largest language family on Earth.

For decades, specialists have debated how Indo-European languages made their way to distant parts of the world. Did they spread via herders from the Eurasian Steppe? Or did they travel with farmers moving west and east from Anatolia (present-day Turkey)?

A 2015 paper by Reich and colleagues indicated that Indo-European languages arrived in Europe via the steppe. The Science study now makes a similar case for South Asia by showing that present-day South Asians have little if any ancestry from farmers with Anatolian roots.

"We can rule out a large-scale spread of farmers with Anatolian roots into South Asia, the centerpiece of the 'Anatolian hypothesis' that such movement brought farming and Indo-European languages into the region," said Reich, who is also an investigator of the Howard Hughes Medical Institute and the Broad Institute. "Since no substantial movements of people occurred, this is checkmate for the Anatolian hypothesis."

One new line of evidence in favor of a steppe origin for Indo-European languages is the detection of genetic patterns that connect speakers of the Indo-Iranian and Balto-Slavic branches of Indo-European. The researchers found that present-day speakers of both branches descend from a subgroup of steppe pastoralists who moved west toward Europe almost 5,000 years ago and then spread back eastward into Central and South Asia in the following 1,500 years.

"This provides a simple explanation in terms of ancient movements of people for the otherwise puzzling shared linguistic features of these two branches of Indo-European, which today are separated by vast geographic distances," said Reich.

A second line of evidence in favor of a steppe origin is the researchers' discovery that of the 140 present-day South Asian populations analyzed in the study, a handful show a remarkable spike in ancestry from the steppe. All but one of these steppe-enriched populations are historically priestly groups, including Brahmins -- traditional custodians of texts written in the ancient Indo-European language Sanskrit.

"The finding that Brahmins often have more steppe ancestry than other groups in South Asia, controlling for other factors, provides a fascinating new argument in favor of a steppe origin for Indo-European languages in South Asia," said Reich.

"This study has filled in a large piece of the puzzle of the spread of Indo-European," said co-author Nick Patterson, research fellow in genetics at HMS and a staff scientist at the Broad Institute of MIT and Harvard. "I believe the high-level picture is now understood."

"This problem has been in the air for 200 years or more and it's now rapidly being sorted out," he added. "I'm very excited by that."

Agriculture origins

The studies inform another longstanding debate, this one about whether the change from a hunting and gathering economy to one based on farming was driven more by movements of people, the copying of ideas or local invention.

In Europe, ancient-DNA studies have shown that agriculture arrived along with an influx of people with ancestry from Anatolia.

The new study reveals a similar dynamic in Iran and Turan (southern Central Asia), where the researchers found that Anatolian-related ancestry and farming arrived around the same time.

"This confirms that the spread of agriculture entailed not only a westward route from Anatolia to Europe but also an eastward route from Anatolia into regions of Asia previously only inhabited by hunter-gatherer groups," said Pinhasi.

Then, as farming spread northward through the mountains of Inner Asia thousands of years after taking hold in Iran and Turan, "the links between ancestry and economy get more complex," said archaeologist Michael Frachetti of Washington University in St. Louis, co-senior author who led much of the skeletal sampling for the Science paper.

By around 5,000 years ago, the researchers found, southwestern Asian ancestry flowed north along with farming technology, while Siberian or steppe ancestry flowed south onto the Iranian plateau. The two-way pattern of movement took place along the mountains, a corridor that Frachetti previously showed was a "Bronze Age Silk Road" along which people exchanged crops and ideas between East and West.

In South Asia, however, the story appears quite different. Not only did the researchers find no trace of the Anatolian-related ancestry that is a hallmark of the spread of farming to the west, but the Iranian-related ancestry they detected in South Asians comes from a lineage that separated from ancient Iranian farmers and hunter-gatherers before those groups split from each other.

The researchers concluded that farming in South Asia was not due to the movement of people from the earlier farming cultures of the west; instead, local foragers adopted it.

"Prior to the arrival of steppe pastoralists bringing their Indo-European languages about 4,000 years ago, we find no evidence of large-scale movements of people into South Asia," said Reich.

First glimpse of the ancestry of the Indus Valley Civilization

Running from the Himalayas to the Arabian Sea, the Indus River Valley was the site of one of the first civilizations of the ancient world, flourishing between 4,000 and 5,000 years ago. People built towns with populations in the tens of thousands. They used standardized weights and measures and exchanged goods with places as far-flung as East Africa.

But who were they?

Before now, geneticists were unable to extract viable data from skeletons buried at Indus Valley Civilization archaeological sites because the heat and volatile climate of lowland South Asia have degraded most DNA beyond scientists' ability to analyze it.

The Cell paper changes this.

After screening more than 60 skeletal samples from the largest known town of the Indus Valley Civilization, called Rakhigarhi, the authors found one with a hint of ancient DNA. After more than 100 sequencing attempts, they generated enough data to reach meaningful conclusions.

The ancient woman's genome matched those of 11 other ancient people reported in the Science paper who lived in what is now Iran and Turkmenistan at sites known to have exchanged objects with the Indus Valley Civilization. All 12 had a distinctive mix of ancestry, including a lineage related to Southeast Asian hunter-gatherers and an Iranian-related lineage specific to South Asia. Because this mix was different from the majority of people living in Iran and Turkmenistan at that time, the authors propose that the 11 individuals reported in the Science paper were migrants, likely from the Indus Valley Civilization.

None of the 12 had evidence of ancestry from steppe pastoralists, consistent with the model that that group hadn't arrived yet in South Asia.

The Science paper further showed that after the decline of the Indus Valley Civilization between 4,000 and 3,500 years ago, a portion of the group to which these 12 individuals belonged mixed with people coming from the north who had steppe pastoralist ancestry, forming the Ancestral North Indians, one of the two primary ancestral populations of present-day people in India. A portion of the original group also mixed with people from peninsular India to form the other primary source population, the Ancestral South Indians.

"Mixtures of the Ancestral North Indians and Ancestral South Indians -- both of whom owe their primary ancestry to people like that of the Indus Valley Civilization individual we sequenced -- form the primary ancestry of South Asians today," said Patterson.

"The study directly ties present-day South Asians to the ancient peoples of South Asia's first civilization," added Narasimhan.

Read more at Science Daily

Neanderthals used resin 'glue' to craft their stone tools

Archaeologists working in two Italian caves have discovered some of the earliest known examples of ancient humans using an adhesive on their stone tools -- an important technological advance called "hafting."

The new study, which included CU Boulder's Paola Villa, shows that Neanderthals living in Europe from about 55 to 40 thousand years ago traveled away from their caves to collect resin from pine trees. They then used that sticky substance to glue stone tools to handles made out of wood or bone.

The findings add to a growing body of evidence that suggests that these cousins of Homo sapiens were more clever than some have made them out to be.

"We continue to find evidence that the Neanderthals were not inferior primitives but were quite capable of doing things that have traditionally only been attributed to modern humans," said Villa, corresponding author of the new study and an adjoint curator at the CU Museum of Natural History.

That insight, she added, came from a chance discovery from Grotta del Fossellone and Grotta di Sant'Agostino, a pair of caves near the beaches of what is now Italy's west coast.

Those caves were home to Neanderthals who lived in Europe during the Middle Paleolithic period, thousands of years before Homo sapiens set foot on the continent. Archaeologists have uncovered more than 1,000 stone tools from the two sites, including pieces of flint that measured not much more than an inch or two from end to end.

In a recent study of the tools, Villa and her colleagues noticed a strange residue on just a handful of the flints -- bits of what appeared to be organic material.

"Sometimes that material is just inorganic sediment, and sometimes it's the traces of the adhesive used to keep the tool in its socket" Villa said.

To find out, study lead author Ilaria Degano at the University of Pisa conducted a chemical analysis of 10 flints using a technique called gas chromatography/mass spectrometry. The tests showed that the stone tools had been coated with resin from local pine trees. In one case, that resin had also been mixed with beeswax.

Villa explained that the Italian Neanderthals didn't just resort to their bare hands to use stone tools. In at least some cases, they also attached those tools to handles to give them better purchase as they sharpened wooden spears or performed other tasks like butchering or scraping leather.

"You need stone tools to cut branches off of trees and make them into a point," Villa said.

The find isn't the oldest known example of hafting by Neanderthals in Europe -- two flakes discovered in the Campitello Quarry in central Italy predate it. But it does suggest that this technique was more common than previously believed.

The existence of hafting also provides more evidence that Neanderthals, like their smaller human relatives, were able to build a fire whenever they wanted one, Villa said -- something that scientists have long debated. She said that pine resin dries when exposed to air. As a result, Neanderthals needed to warm it over a small fired to make an effective glue.

"This is one of several proofs that strongly indicate that Neanderthals were capable of making fire whenever they needed it," Villa said.

In other words, enjoying the glow of a warm campfire isn't just for Homo sapiens.

Read more at Science Daily

Artificial intelligence for studying the ancient human populations of Patagonia

Technological landscapes of nautical mobility (red circles, with some blues that are less well classified by the algorithm) and pedestrian mobility (orange and purple circles) in hunter-gatherer groups that lived in the extreme south of South America.

Argentine and Spanish researchers have used statistical techniques of automatic learning to analyze mobility patterns and technology of the hunter-gatherer groups that inhabited the Southern Cone of America, from the time they arrived about 12,000 years ago until the end of the 19th century. Big data from archaeological sites located in the extreme south of Patagonia have been used for this study.

The presence of humans on the American continent dates back to at least 14,500 years ago, according to datings made at archaeological sites such as Monte Verde, in Chile's Los Lagos Region. But the first settlers continued moving towards the southernmost confines of America.

Now, researchers from Argentina's National Council for Scientific and Technical Research (CONICET) and two Spanish institutions (the Spanish National Research Council and the University of Burgos) have analyzed the relationships between mobility and technology developed by those societies that originated in the far south of Patagonia.

The study, published in the Royal Society Open Science journal, is based on an extensive database of all available archaeological evidence of human presence in this region, from the time the first groups arrived in the early Holocene (12,000 years ago) until the end of the 19th century.

This was followed by the application of machine learning techniques, a statistical system that allows the computer to learn from many data (in this case, big data from characteristic technological elements of the sites) in order to carry out classifications and predictions.

"It is by means of automatic classification algorithms that we have identified two technological packages or 'landscapes': one that characterizes pedestrian hunter-gatherer groups (with their own stone and bone tools) and the other characterizing those that had nautical technology, such as canoes, harpoons and mollusc shells used to make beads," explains Ivan Briz i Godino, an archaeologist of the National Council for Scientific and Technical Research (CONICET) of Argentina and co-author of the work.

"In future excavations, when sets of technological elements such as those we have detected appear, we'll be able to directly deduce the type of mobility of the group or the connections with other communities," adds Briz.

The results of the study have also made it possible to obtain maps with the settlements of the two communities, and this, in turn, has made it possible to locate large regions in which they interacted and shared their technological knowledge. In the case of groups with nautical technology, it has been confirmed that they arrived at around the beginning of the Mid-Holocene (some 6,000 years ago) from the channels and islands of the South Pacific, moving along the coast of what is now Chile.

Read more at Science Daily

Northern European population history revealed by ancient human genomes

Skull included in this study from Ölsund, Hälsingland, Sweden, dating to around 2,300 BCE, in the ancient DNA laboratory at the Max Planck Institute for the Science of Human History.

An international team of scientists, led by researchers from the Max Planck Institute for the Science of Human History, analyzed ancient human genomes from 38 northern Europeans dating from approximately 7,500 to 500 BCE. The study, published today in Nature Communications, found that Scandinavia was initially settled via a southern and a northern route and that the arrival of agriculture in northern Europe was facilitated by movements of farmers and pastoralists into the region.

Northern Europe could be considered a late bloomer in some aspects of human history: initial settlement by hunter-gatherers occurred only about 11,000 years ago, after the retreat of the lingering ice sheets from the Pleistocene, and while agriculture was already widespread in Central Europe 7,000 years ago, this development reached Southern Scandinavia and the Eastern Baltic only millennia later.

Several recent studies of ancient human genomes have dealt with the prehistoric population movements that brought new technology and subsistence strategies into Europe, but how they impacted the very north of the continent has still been poorly understood.

For this study, the research team, which included scientists from Lithuania, Latvia, Estonia, Russia and Sweden, assembled genomic data from 38 ancient northern Europeans, from mobile hunter-gatherers of the Mesolithic (approximately 12,000 to 7,000 years ago) and the first Neolithic farmers in southern Sweden (approximately 6,000 to 5,300 years ago) to the metallurgists of the Late Bronze Age in the Eastern Baltic (approximately 1300 to 500 BCE). This allowed the researchers to uncover surprising aspects of the population dynamics of prehistoric northern Europe.

Two routes of settlement for Scandinavia

Previous analysis of ancient human genomes has revealed that two genetically differentiated groups of hunter-gatherers lived in Europe during the Mesolithic: the so-called Western Hunter-Gatherers excavated in locations from Iberia to Hungary, and the so-called Eastern Hunter-Gatherers excavated in Karelia in north-western Russia. Surprisingly, the results of the current study show that Mesolithic hunter-gatherers from Lithuania appear very similar to their Western neighbors, despite their geographic proximity to Russia. The ancestry of contemporary Scandinavian hunter-gatherers, on the other hand, was comprised from both Western and Eastern Hunter-Gatherers.

"Eastern Hunter-Gatherers were not present on the eastern Baltic coast, but a genetic component from them is present in Scandinavia. This suggests that the people carrying this genetic component took a northern route through Fennoscandia into the southern part of the Scandinavian peninsula. There they genetically mixed with Western Hunter-Gatherers who came from the South, and together they formed the Scandinavian Hunter-Gatherers," explains Johannes Krause, Director of the Department of Archaeogenetics at the Max Planck Institute for the Science of Human History, and senior author of the study.

Agriculture and animal herding -- cultural imports by incoming people

Large-scale farming first started in southern Scandinavia around 6,000 years ago, about one millennium after it was already common in Central Europe. In the Eastern Baltic, the inhabitants relied solely on hunting, gathering and fishing for another 1000 years. Although some have argued that the use of the new subsistence strategy was a local development by foragers, possibly adopting the practices of their farming neighbors, the genetic evidence uncovered in the present study tells a different story.

The earliest farmers in Sweden are not descended from Mesolithic Scandinavians, but show a genetic profile similar to that of Central European agriculturalists. Thus it appears that Central Europeans migrated to Scandinavia and brought farming technology with them. These early Scandinavian farmers, like the Central European agriculturalists, inherited a substantial portion of their genes from Anatolian farmers, who first spread into Europe around 8,200 years ago and set in motion the cultural transition to agriculture known as the Neolithic Revolution.

Similarly, a near-total genetic turnover is seen in the Eastern Baltic with the advent of large-scale agro-pastoralism. While they did not mix genetically with Central European or Scandinavian farmers, beginning around 2,900 BCE the individuals in the Eastern Baltic derive large parts of their ancestry from nomadic pastoralists of the Pontic-Caspian steppe.

"Interestingly, we find an increase of local Eastern Baltic hunter-gatherer ancestry in this population at the onset of the Bronze Age," states Alissa Mittnik of the Max Planck Institute for the Science of Human History, lead author of the study. "The local population was not completely replaced but coexisted and eventually mixed with the newcomers."

Read more at Science Daily

Archaeologist says fire, not corn, key to prehistoric survival in arid Southwest

UC professor Alan Sullivan's research is challenging the assumption that prehistoric people subsisted on corn in America's Southwest. Instead, he said evidence suggests they used fire to cultivate wild foods.

Conventional wisdom holds that prehistoric villagers planted corn, and lots of it, to survive the dry and hostile conditions of the American Southwest.

But University of Cincinnati archaeology professor Alan Sullivan is challenging that long-standing idea, arguing instead that people routinely burned the understory of forests to grow wild crops 1,000 years ago.

"There has been this orthodoxy about the importance of corn," said Sullivan, director of graduate studies in UC's Department of Anthropology in the McMicken College of Arts and Sciences. "It's been widely considered that prehistoric peoples of Arizona between A.D. 900 to 1200 were dependent on it.

"But if corn is lurking out there in the Grand Canyon, it's hiding successfully because we've looked all over and haven't found it."

Sullivan has published a dozen papers outlining the scarce evidence of corn agriculture at more than 2,000 sites where they have found pottery sherds and other artifacts of prehistoric human settlement. He summarized his findings in a presentation last month at Boston University.

Sullivan has spent more than two decades leading archaeological field research to Grand Canyon National Park and the region's Upper Basin, home to the 1.6-million-acre Kaibab National Forest.

When you think of the Grand Canyon, you might picture rocky cliffs and desert vistas. But the Upper Basin, where Sullivan and his students work, is home to mature forests of juniper and pinyon trees stretching as far as you can see, he said.

"When you look down into the Grand Canyon, you don't see any forest. But on either rim there are deep, dense forests," he said.

On these high-elevation plateaus, Sullivan and his students have unearthed ceramic jugs adorned with corrugated patterns and other evidence of prehistoric life. Sullivan is particularly interested in the cultural and social practices of growing, sharing and eating food, also called a foodway.

"What would constitute evidence of a corn-based foodway?" he asked. "And if experts agree it should look like this but we don't find evidence of it, that would seem to be a problem for that model."

Like a detective, Sullivan has pieced together clues firsthand and from scientific analysis to make a persuasive argument that people used fire to promote the growth of edible leaves, seeds and nuts of plants such as amaranth and chenopodium, wild relatives of quinoa. These plants are called "ruderals," which are the first to grow in a forest disturbed by fire or clear-cutting.

"It's definitely a paradigm-threatening opinion," Sullivan said. "It's not based on wild speculation. It's evidence-based theorizing. It has taken us about 30 years to get to the point where we can confidently conclude this."

Lab analysis identified ancient pollen from dirt inside clay pots that were used 1,000 years ago before Sullivan and his students found them.

"They've identified 6,000 or 7,000 pollen grains and only six [grains] were corn. Everything else is dominated by these ruderals," Sullivan said.

The corn itself looked nothing like the hearty ears of sweet corn people enjoy at barbecues today. The ears were puny, about one-third the size of a typical cob, with tiny, hard kernels, Sullivan said.

So if prehistoric people were not growing corn, what were they eating? Sullivan found clues around his excavation sites that people set fires big enough to burn away the understory of grasses and weeds but small enough not to harm the pinyon and juniper trees, important sources of calorie-rich nuts and berries.

Evidence for this theory was found in ancient trees. Raging wildfires leave burn scars in growth rings of surviving trees. In the absence of frequent small fires, forests would accumulate vast amounts of underbrush and fallen timber to create conditions ripe for an inferno sparked by a lightning strike. But examinations of ancient juniper and ponderosa pine trees found no burn scars, suggesting big fires are a relatively new phenomenon in Arizona.

"To me that confirms there weren't massive fires back then," Sullivan said.

Sullivan also studied the geologic layers at these sites. Like a time capsule, the stratigraphic analysis captured the periods before and after people lived there. He found higher concentrations of wild edible plants in the period when people lived there. And when people abandoned the sites, the area they left behind saw fewer of these plants.

But it was only this year that Sullivan found contemporary evidence supporting his theory that prehistoric people generated a spring bounty by setting fires. Sullivan returned to the Grand Canyon last spring to examine forest destroyed by a massive 2016 fire. Touched off by a lightning strike, the blaze called the Scott Fire laid waste to 2,660 acres of pines, junipers and sagebrush.

Despite the intensity of the forest fire, Sullivan found edible plants growing thick everywhere underfoot just months later.

"This burned area was covered in ruderals. Just covered," he said. "That to us was confirmation of our theory. Our argument is there's this dormant seed bed that is activated by any kind of fire."

Archaeologists with the National Park Service have found evidence that corn grew below the rim of the Grand Canyon, said Ellen Brennan, cultural resource program manager for the national park.

"It does appear that the ancient people of the Grand Canyon never pursued corn agriculture to the extent that other ancestral Puebloan peoples did in other parts of the Southwest," Brennan said. "In the Grand Canyon, it appears that there continued to be persistent use of native plants as a primary food source rather than corn."

The National Park Service has not examined whether prehistoric people used fire to improve growing conditions for native plants. But given what is known about cultures at the time, it is likely they did, Brennan said.

The first assumptions about what daily life was like in the Southwest 1,000 years ago came from more recent observations of Native Americans such as the Hopi, said Neil Weintraub, archaeologist for Kaibab National Forest. He worked alongside Sullivan at some of the sites in the Upper Basin.

"Corn is still a big part of the Hopi culture. A lot of dances they do are about water and the fertility of corn," he said. "The Hopi are seen as the descending groups of Puebloan."

While native peoples elsewhere in the Southwest no doubt relied on corn, Weintraub said, Sullivan's work has convinced him that residents of the Upper Basin relied on wild food -- and used fire to cultivate it.

"It's a fascinating idea because we really see that these people were highly mobile. On the margins where it's very dry we think they were taking advantage of different parts of the landscape at different times of the year," Weintraub said.

"It's been well documented that Native Americans burned the forest in other parts of the country. I see no reason why they wouldn't have been doing the same thing 1,000 years ago," he said.

The area around the Grand Canyon is especially dry, going many weeks without rain. Still, life persists. Weintraub said the forest generates a surprising bounty of food if you know where to look. Some years, the pinyon trees produce a bumper crop of tasty, nutritious nuts.

"In a good year, we didn't need to bring lunch in the field when we were out at our archaeological surveys. We'd be cracking pinyons all day," Weintraub said.

Weintraub recently studied the forest burned in last year's big Scott Fire. The exposed ground was thick with new undergrowth, particularly a wild relative of quinoa called goosefoot, he said.

"Goosefoot has a minty smell to it, especially in the fall. We actually started chewing on it. It was pretty pleasant," Weintraub said. "It's a high-nutrient food. I'd be curious to know more about how native peoples processed it for food."

UC's Sullivan said this prehistoric land management can teach us lessons today, especially when it comes to preventing devastating fires.

"Foresters call it 'the wicked problem.' All of our forests are anthropogenic [human-made] because of fire suppression and fire exclusion," Sullivan said.

"These forests are unnatural. They're alien to the planet. They have not had any major fires in them in decades," he said. "The fuel loads have built up to the point where you get a little ignition source and the fire is catastrophic in ways that they rarely were in the past."

The National Park Service often lets fires burn in natural areas when they do not threaten people or property. But increasingly people are building homes and businesses adjacent to or within forests. Forest managers are reluctant to conduct controlled burning so close to population, Sullivan said.

Eventually so much dry wood builds up that a dropped cigarette or unattended campfire can lead to devastating fires such as the 2016 blaze that killed 14 people and destroyed 11,000 acres in the Great Smoky Mountains or the fires in California this year that killed 40 people and caused an estimated $1 billion in property damage.

"It's a chronic problem. How do you fix it?" he asked. "The U.S. Forest Service has experimented with different methods: prescribed burning, which creates a lot of irritating smoke, or thinning the forest, which creates a disposal problem."

Fire also seems to increase the diversity of forest species. Sullivan said vegetation surveys find less biodiversity in forests today than he found in his archeological samples.

"That is one measure of how devastating our management of fire has been to these forests," he said. "These fire-responsive plants have basically disappeared from the landscape. Species diversity in some cases has collapsed."

Today, federal land managers conduct controlled burns when practical to address this problem, even in national parks such as the Grand Canyon.

"The fire management program for Grand Canyon National Park seeks to reintroduce fire as a natural agent of the environment," the park's Brennan said. "That is to reduce ground fuels through prescribed fire, mechanical thinning, and wildland fire."

Scientists also are studying how to adjust forest management techniques in the face of climate change, she said.

"Program managers are working to understand how climate change affects forest management and how to restore forests to the point where fire can follow a more natural return interval given a particular forest type," she said.

Climate change is expected to make wildfires more frequent and severe with rising temperatures and lower humidity. Meanwhile, public lands are under increasing pressure from private interests such as tourism and mining, putting more people at potential risk from fire, Sullivan said.

Read more at Science Daily

Ancient humans left Africa to escape drying climate

The Lamont-Doherty Core Repository contains a unique and important collection of scientific samples from the deep sea. Sediment cores from every major ocean and sea are archived here.

Humans migrated out of Africa as the climate shifted from wet to very dry about 60,000 years ago, according to research led by a University of Arizona geoscientist.

Genetic research indicates people migrated from Africa into Eurasia between 70,000 and 55,000 years ago. Previous researchers suggested the climate must have been wetter than it is now for people to migrate to Eurasia by crossing the Horn of Africa and the Middle East.

"There's always been a question about whether climate change had any influence on when our species left Africa," said Jessica Tierney, UA associate professor of geosciences. "Our data suggest that when most of our species left Africa, it was dry and not wet in northeast Africa."

Tierney and her colleagues found that around 70,000 years ago, climate in the Horn of Africa shifted from a wet phase called "Green Sahara" to even drier than the region is now. The region also became colder.

The researchers traced the Horn of Africa's climate 200,000 years into the past by analyzing a core of ocean sediment taken in the western end of the Gulf of Aden. Tierney said before this research there was no record of the climate of northeast Africa back to the time of human migration out of Africa.

"Our data say the migration comes after a big environmental change. Perhaps people left because the environment was deteriorating," she said. "There was a big shift to dry and that could have been a motivating force for migration."

"It's interesting to think about how our ancestors interacted with climate," she said.

The team's paper, "A climatic context for the out-of-Africa migration," is published online in Geology this week. Tierney's co-authors are Peter deMenocal of the Lamont-Doherty Earth Observatory in Palisades, New York, and Paul Zander of the UA.

The National Science Foundation and the David and Lucile Packard Foundation funded the research.

Tierney and her colleagues had successfully revealed the Horn of Africa's climate back to 40,000 years ago by studying cores of marine sediment. The team hoped to use the same means to reconstruct the region's climate back to the time 55,000 to 70,000 years ago when our ancestors left Africa.

The first challenge was finding a core from that region with sediments that old. The researchers enlisted the help of the curators of the Lamont-Doherty Core Repository, which has sediment cores from every major ocean and sea. The curators found a core collected off the Horn of Africa in 1965 from the R/V Robert D. Conrad that might be suitable.

Co-author deMenocal studied and dated the layers of the 1965 core and found it had sediments going back as far as 200,000 years.

At the UA, Tierney and Paul Zander teased out temperature and rainfall records from the organic matter preserved in the sediment layers. The scientists took samples from the core about every four inches (10 cm), a distance that represented about every 1,600 years.

To construct a long-term temperature record for the Horn of Africa, the researchers analyzed the sediment layers for chemicals called alkenones made by a particular kind of marine algae. The algae change the composition of the alkenones depending on the water temperature. The ratio of the different alkenones indicates the sea surface temperature when the algae were alive and also reflects regional temperatures, Tierney said.

To figure out the region's ancient rainfall patterns from the sediment core, the researchers analyzed the ancient leaf wax that had blown into the ocean from terrestrial plants. Because plants alter the chemical composition of the wax on their leaves depending on how dry or wet the climate is, the leaf wax from the sediment core's layers provides a record of past fluctuations in rainfall.

The analyses showed that the time people migrated out of Africa coincided with a big shift to a much drier and colder climate, Tierney said.

The team's findings are corroborated by research from other investigators who reconstructed past regional climate by using data gathered from a cave formation in Israel and a sediment core from the eastern Mediterranean. Those findings suggest that it was dry everywhere in northeast Africa, she said.

Read more at Science Daily

Why your ancestors would have aced the long jump

This tiny ankle bone belonged to one of the earliest members of the primate family tree. The 52-million-year-old fossil suggests that the first primates were expert leapers. Discovered more than 30 years ago by paleontologist Marc Godinot, the fossil is now housed at the Muséum National d'Histoire Naturelle in Paris.

A 52-million-year-old ankle fossil suggests our prehuman ancestors were high-flying acrobats.

These first primates spent most of their time in the trees rather than on the ground, but just how nimble they were as they moved around in the treetops has been a topic of dispute.

For years, scientists thought the ancestors of today's humans, monkeys, lemurs and apes were relatively slow and deliberate animals, using their grasping hands and feet to creep along small twigs and branches to stalk insects or find flowers and fruits.

But a fossil study published in the October 2017 issue of the Journal of Human Evolution suggests the first primates were masters at leaping through the trees.

Paleontologists working in a quarry in southeastern France uncovered the quarter-inch-long bone, the lower part of the ankle joint.

The fossil matched up best with a chipmunk-sized creature called Donrussellia provincialis.

Previously only known from jaws and teeth, Donrussellia is thought be one of the earliest members of the primate family tree, on the branch leading to lemurs, lorises and bush babies.

Duke University assistant professor Doug Boyer and colleagues studied scans of Donrussellia's ankle and compared it to other animals, using computer algorithms to analyze the 3-D digital shape of each tiny bone.

They were surprised to find that Donrussellia's ankle was not like those of other primates, but was more similar to those of treeshrews and other nonprimate species.

The team's analyses also suggest the animal didn't just clamber or scurry along small branches. Instead, it may have been able to bound between trunks and branches, using its grasping feet to stick the landing.

The researchers say that -- contrary to what many scientists thought -- the first primates may have evolved their acrobatic leaping skills first, while anatomical changes that allowed them to cling to slender branch tips and creep from tree to tree came later.

Read more at Science Daily

In saliva, clues to a 'ghost' species of ancient human

Neanderthal. In saliva, scientists have found hints that a "ghost" species of archaic human may have contributed genetic material to ancestors of people living in Sub-Saharan Africa today.

In saliva, scientists have found hints that a "ghost" species of archaic humans may have contributed genetic material to ancestors of people living in Sub-Saharan Africa today.

The research adds to a growing body of evidence suggesting that sexual rendezvous between different archaic human species may not have been unusual.

Past studies have concluded that the forebears of modern humans in Asia and Europe interbred with other early hominin species, including Neanderthals and Denisovans. The new research is among more recent genetic analyses indicating that ancient Africans also had trysts with other early hominins.

"It seems that interbreeding between different early hominin species is not the exception -- it's the norm," says Omer Gokcumen, PhD, an assistant professor of biological sciences in the University at Buffalo College of Arts and Sciences.

"Our research traced the evolution of an important mucin protein called MUC7 that is found in saliva," he says. "When we looked at the history of the gene that codes for the protein, we see the signature of archaic admixture in modern day Sub-Saharan African populations."

The research was published on July 21 in the journal Molecular Biology and Evolution. The study was led by Gokcumen and Stefan Ruhl, DDS, PhD, a professor of oral biology in UB's School of Dental Medicine.

A tantalizing clue in saliva

The scientists came upon their findings while researching the purpose and origins of the MUC7 protein, which helps give spit its slimy consistency and binds to microbes, potentially helping to rid the body of disease-causing bacteria.

As part of this investigation, the team examined the MUC7 gene in more than 2,500 modern human genomes. The analysis yielded a surprise: A group of genomes from Sub-Saharan Africa had a version of the gene that was wildly different from versions found in other modern humans.

The Sub-Saharan variant was so distinctive that Neanderthal and Denisovan MUC7 genes matched more closely with those of other modern humans than the Sub-Saharan outlier did.

"Based on our analysis, the most plausible explanation for this extreme variation is archaic introgression -- the introduction of genetic material from a 'ghost' species of ancient hominins," Gokcumen says. "This unknown human relative could be a species that has been discovered, such as a subspecies of Homo erectus, or an undiscovered hominin. We call it a 'ghost' species because we don't have the fossils."

Given the rate that genes mutate during the course of evolution, the team calculated that the ancestors of people who carry the Sub-Saharan MUC7 variant interbred with another ancient human species as recently as 150,000 years ago, after the two species' evolutionary path diverged from each other some 1.5 to 2 million years ago.

Why MUC7 matters

The scientists were interested in MUC7 because in a previous study they showed that the protein likely evolved to serve an important purpose in humans.

In some people, the gene that codes for MUC7 holds six copies of genetic instructions that direct the body to build parts of the corresponding protein. In other people, the gene harbors only five sets of these instructions (known as tandem repeats).

Prior studies by other researchers found that the five-copy version of the gene protected against asthma, but Gokcumen and Ruhl did not see this association when they ran a more detailed analysis.

The new study did conclude, however, that MUC7 appears to influence the makeup of the oral microbiome, the collection of bacteria within the mouth. The evidence for this came from an analysis of biological samples from 130 people, which found that different versions of the MUC7 gene were strongly associated with different oral microbiome compositions.

Read more at Science Daily

Groundwater 'pit stops' enabled survival, migration of our ancient ancestors

Oasis in Morocco

An international team led by a researcher at Cardiff University believe that the movement of our ancestors across East Africa was shaped by the locations of groundwater springs.

In a new study, the team argue that the springs acted as pit stops to allow early humans to survive as they moved across the African landscape.

The team believe that populations were able to mix with each other at these junctions, influencing genetic diversity and, ultimately, the evolution of the human population.

The results of the study have been published in the journal Nature Communications.

Humans are thought to have first evolved in Africa, and evidence currently suggests that early humans first migrated out of the continent probably between 2 million and 1.8 million years ago.

During this time, rainfall was affected by the African monsoon which strengthened and weakened on a 23,000 year cycle driven by the precession of the equinoxes. During intense periods of aridity, monsoon rains would have been light and drinking water in short supply.

By mapping persistent springs across the African landscape, the researchers have been able to model how our ancestors may have moved between water sources at different times and how this impacted their ability to traverse the landscape as the climate changed.

Lead author of the study Dr Mark Cuthbert, from Cardiff University's School of Earth and Ocean Sciences, said: "We found that the geology is really important in controlling how much rainfall gets stored in the ground during wet periods. Modelling the springs showed that many could still flow during long dry periods because this groundwater store acts like a buffer against climate change.

"As such, we begin to see that the geology, and not just the climate, control the availability of water -- the landscape was a catalyst for change in Africa."

Co-author of the study Professor Matthew Bennett, from Bournemouth University, said: "What we are seeing is the movement of people across vast areas of land. You can think of springs as the service stations or rest stops along the way, where people would be drawn to get their vital water sources.

"Through our mapping we have found the routes on the current landscape by which our ancestors may have walked, like motorways, taking people from one water source to the next. This is another vital clue in understanding how these people migrated across the African continent, from water source to source, and how this may have impacted on gene flow and mixing."

Read more at Science Daily

Ancient Hunter-Gatherers and Farmers Made Love, Not War

Facial reconstruction of a hunter-gatherer woman from Chan do Lindeiro, Spain, who lived about 9,000 years ago.

For much of human history, our ancestors were hunter-gatherers, mostly nomadic people who lived by hunting, fishing and harvesting wild food. Around 10,000 years ago, farming developed in Western Asia and quickly spread across Europe and to other parts of the world. The ancient lifestyle shift begs the question: What happened when the farmers first encountered the hunter-gatherers?

New DNA evidence reported in the journal Current Biology helps to provide the answer by showing that, at least in the area now known as Romania, hunter-gatherers and farmers were living side by side, intermixing with each other, and having children.

It was not necessarily love at first sight, though.

“Farmers arrived very suddenly, as a result of a fast expansion,” co-author Andrea Manica of the University of Cambridge said. “It is likely that they lived side by side with local hunter-gatherer populations for a period of time — centuries or even a millennium or two — with increasing contact and mixing among the two communities.”

Manica, lead author Gloria Gonzalez-Fortes, and their international team came to these conclusions after recovering four ancient human genomes from Romania dating to between 8.8–5.4 thousand years ago. For context, they analyzed two hunter-gatherer genomes from Spain, as well as other known early genomes from these European regions.

Co-author Clive Bonsall from the University of Edinburgh explained that indigenous hunter-gatherers can be distinguished archaeologically from immigrant farmers by their material culture, such as artifacts, architecture, burial traditions, art, and body ornamentation. The two groups also differ in subsistence practices, determined by food refuse preserved in the archaeological record and chemical analysis of human remains.

“For example, in our study region, hunter-gatherers did not cultivate or raise livestock, although they did keep domestic dogs," Bonsall said. "They did not use pottery, and buried their dead in a different way.”

The DNA analysis revealed that the early Romanian genomes had significant input from Western hunter-gatherers, but still showed a sizable contribution from Anatolian farmers. This suggests that some hunter-gatherers and farmers were mating and raising children.

The scientists suspect that the challenging climate of the region might have caused the farmers to supplement their diet with food from hunter-gatherer activities, helping to bring the two distinct groups of people together.

Skeleton within a burial at Schela Cladovei, Romania.

Chemical investigation of related human bones demonstrates that the joining of the two cultures broadened the diets of each. Bonsall said early Southeast European farmers cultivated cereals, such as wheat and barley, and legumes, like peas and lentils. They also raised sheep, goats, cattle, and pigs.

They additionally consumed some dairy products, even though all of the individuals examined in the study were lactose intolerant. Co-author Eppie Jones of the University of Cambridge explained that “the mutation, which allowed people to drink milk into adulthood, has not been found in Europe before the Bronze Age (starting around 2300 B.C.).”

The hunter-gatherers, on the other hand, brought plenty of nuts, plant foods, fish, and shellfish to the table. Some hunter-gatherers along the lower Danube River were so good at fishing that they lived in more permanent settlements, known as fishing villages.

Previously it was thought that farmers horned in on the hunter-gatherer territory and outcompeted the native populations, but the DNA evidence indicates that, at least in some cases, the two groups managed to live together despite large cultural differences.

Jones mentioned that the new findings, combined with prior research, reveal that “the amount of mixing between the groups varies in different regions of Europe. In Central and Western Europe, the incoming farmers largely replaced the local populations, while in areas further north, such as the Baltic, farmers didn’t make much of a genetic impact.”

Read more at Discovery News

Pre-Human Fossils Suggest Mankind Emerged From Europe Rather Than Africa

Illustration of ‘El Graeco,’ foreground, living in a savannah environment in the Eastern Mediterranean 7.2 million years ago.

When an ancient, toothy lower jaw was found in 1944 in Pyrgos Vassilissis, Greece, few paid much attention to the fossil. World War II was still underway, so the discovery was largely overlooked by all but the most ardent anthropologists. Even Pyrgos Vassilissis, a former royal estate on the Greek mainland, is often bypassed by travelers on their way to bustling Athens.

Interest in both the fossil and Pyrgos Vassilissis may soon grow, however, owing to the announcement of an explosive finding by an international team of researchers. In a paper published in the journal PLOS ONE, the scientists outline how the jaw likely belonged to the earliest known hominin, or pre-human — providing evidence that the last common ancestor of chimps and humans lived in the Eastern Mediterranean.

A second paper describes what this region’s climate was like during the lifetime of the human-ish species, Graecopithecus freybergi, otherwise known informally as “El Graeco.” Taken together, the findings support the idea that regal Pyrgos Vassilissis lies within the site where humanity first evolved 7.2 million years ago.

Project leader Madelaine Böhme of the Senckengberg Center for Human Evolution and Paleoenvironment at the University of Tübingen, co-author Nikolai Spassov from the Bulgarian Academy of Sciences, and their colleagues analyzed both the Pyrgos fossil and a related upper premolar tooth unearthed in Azmaka, Bulgaria.

The lower jaw of the 7.2-million-year-old Graecopithecus freybergi (El Graeco) from Pyrgos Vassilissis, Greece.

“El Graeco is the oldest known potential hominin,” Spassov said. He is several hundred thousand years older than the oldest potential pre-human from Africa: 6–7-million-year-old Sahelanthropus from Chad.

Anthropologists use the term hominin, or pre-human, because the last common ancestor of humans and chimps clearly retained both non-human primate and human characteristics. Although El Graeco is only known from the fossil jaw and premolar, Böhme and her team could see how these features were evolving into more human-like forms. Computer tomography visualized the internal structures of the fossils and found that the roots of the premolars were widely fused.

“While great apes typically have two or three separate and diverging roots,” Böhme said in a statement, “the roots of Graecopithecus converge and are partially fused — a feature that is characteristic of modern humans, early humans and several pre-humans including Ardipithecus and Australopithecus.”

“No other fossil and living non-human primate is known with such roots,” Spassov said, adding that the analysis of El Graeco’s environment determined that it was a savannah when this individual was alive.

A 7.2-million-year-old upper premolar of Graecopithecus from Azmaka, Bulgaria.

The researchers studied microscopic fragments of charcoal and plant silicate particles, called phytoliths, to reconstruct what the past climate was like both in the Eastern Mediterranean and North Africa.

“The phytolith record provides evidence of severe droughts, and the charcoal analysis indicates recurring vegetation fires,” Böhme said. “In summary, we reconstruct a savannah, which fits with the giraffes, gazelles, antelopes, and rhinoceroses that were found together with Graecopithecus.”

The scientists further studied salts as well as uranium, thorium, and lead isotopes discovered in dust particles originating from the Sahara Desert and that are often transported during storms to the Mediterranean. Dating of these materials, and analysis of their spread, suggests that the Sahara originated around 8–7 million years ago.

Electron microscope image of a dust particle rounded by wind transport. It originated in the Sahara Desert and was found in 7.2-million-year-old sediments in Greece.

“The incipient formation of a desert in North Africa more than 7 million years ago and the spread of savannahs in Southern Europe may have played a central role in the splitting of the human and chimpanzee lineages,” Böhme said.

The theory is now called the North Side Story, recalling a hypothesis made by anthropologist Yves Coppens, co-discoverer of the famous hominin “Lucy.” Coppens’ theory, known as the East Side Story, holds that pre-humans first evolved in Kenya’s Rift Valley.

Read more at Discovery News