Researchers shed new light on the origins of modern humans

Researchers shed new light on the origins of modern humans

The work, published in Nature, confirms a dispersal of Homo sapiens from southern to eastern Africa immediately preceded the out-of-Africa migration

out-of-Africa migration dispersal of Homo sapiens origins of modern humans eastern Africa
This is a map showing early African archaeological sites with evidence for symbolic material and microlithic stone tools. Credit: NASA Goddard Space Flight Center Image by Reto Stöckli

RESEARCHERS from the University of Huddersfield, with colleagues from the University of Cambridge and the University of Minho in Braga, have been using a genetic approach to tackle one of the most intractable questions of all - how and when we became truly human.

Modern Homo sapiens first arose in Africa more than 300,000 years ago, but there is great controversy amongst scholars about whether the earliest such people would have been 'just like us' in their mental capacities - in the sense that, if they were brought up in a family from Yorkshire today, for example, would they be indistinguishable from the rest of the population? Nevertheless, archaeologists believe that people very like us were living in small communities in an Ice Age refuge on the South African coast by at least 100,000 years ago.

Between around 100,000 and 70,000 years ago, these people left plentiful evidence that they were thinking and behaving like modern humans - evidence for symbolism, such as the use of pigments (probably for body painting), drawings and engravings, shell beads, and tiny stone tools called microliths that might have been part of bows and arrows. Some of this evidence for what some archaeologists call "modern human behaviour" goes back even further, to more than 150,000 years.

But if these achievements somehow made these people special, suggesting a direct line to the people of today, the genetics of their modern "Khoi-San" descendants in southern Africa doesn't seem to bear this out. Our genomes imply that almost all modern non-Africans from all over the world - and indeed most Africans too - are derived from a small group of people living not in South Africa but in East Africa, around 60,000-70,000 years ago. There's been no sign so far that southern Africans contributed to the huge expansion of Homo sapiens out of Africa and across the world that took place around that time.

That is, until now. The Huddersfield-Minho team of geneticists, led by Professor Martin Richards at Huddersfield and Dr Pedro Soares in Braga, along with the eminent Cambridge archaeologist Professor Sir Paul Mellars, have studied the maternally-inherited mitochondrial DNA from Africans in unprecedented detail, and have identified a clear signal of a small-scale migration from South Africa to East Africa that took place at just that time, around 65,000 years ago. The signal is only evident today in the mitochondrial DNA. In the rest of the genome, it seems to have been eroded away to nothing by recombination - the reshuffling of chromosomal genes between parents every generation, which doesn't affect the mitochondrial DNA - in the intervening millennia.

The migration signal makes good sense in terms of climate. For most of the last few hundred years, different parts of Africa have been out of step with each other in terms of the aridity of the climate. Only for a brief period at 60,000-70,000 years ago was there a window during which the continent as a whole experienced sufficient moisture to open up a corridor between the south and the east. And intriguingly, it was around 65,000 years ago that some of the signs of symbolism and technological complexity seen earlier in South Africa start to appear in the east.

The identification of this signal opens up the possibility that a migration of a small group of people from South Africa towards the east around 65,000 years ago transmitted aspects of their sophisticated modern human culture to people in East Africa. Those East African people were biologically little different from the South Africans - they were all modern Homo sapiens, their brains were just as advanced and they were undoubtedly cognitively ready to receive the benefits of the new ideas and upgrade. But the way it happened might not have been so very different from a modern isolated stone-age culture encountering and embracing western civilization today.

In any case, it looks as if something happened when the groups from the South encountered the East, with the upshot being the greatest diaspora of Homo sapiens ever known - both throughout Africa and out of Africa to settle much of Eurasia and as far as Australia within the space of only a few thousand years.

Professor Mellars commented: "This work shows that the combination of genetics and archaeology working together can lead to significant advances in our understanding of the origins of Homo sapiens."

###

* The article, A dispersal of Homo sapiens from southern to eastern Africa immediately preceded the out-of-Africa migration, can be found online in Scientific Reports.

 

Press release from the University of Huddersfield


farmers from Anatolia hunter-gatherers Turkey agriculture

First Anatolian farmers were local hunter-gatherers that adopted agriculture

First Anatolian farmers were local hunter-gatherers that adopted agriculture

The first farmers from Anatolia, who brought farming to Europe and represent the single largest ancestral component in modern-day Europeans, are directly descended from local hunter-gatherers who adopted a farming way of life

An international team, led by scientists from the Max Planck Institute for the Science of Human History and in collaboration with scientists from the United Kingdom, Turkey and Israel, has analyzed 8 pre-historic individuals, including the first genome-wide data from a 15,000-year-old Anatolian hunter-gatherer, and found that the first Anatolian farmers were direct descendants of local hunter-gatherers. These findings provide support for archaeological evidence that farming was adopted and developed by local hunter-gatherers who changed their subsistence strategy, rather than being introduced by a large movement of people from another area. Interestingly, while the study shows the long-term persistence of the Anatolian hunter-gatherer gene pool over 7,000 years, it also indicates a pattern of genetic interactions with neighboring groups.

Farming was developed approximately 11,000 years ago in the Fertile Crescent, a region that includes present-day Iraq, Syria, Israel, Lebanon, Egypt and Jordan as well as the fringes of southern Anatolia and western Iran. By about 8,300 BCE it had spread to central Anatolia, in present-day Turkey. These early Anatolian farmers subsequently migrated throughout Europe, bringing this new subsistence strategy and their genes. Today, the single largest component of the ancestry of modern-day Europeans comes from these Anatolian farmers. It has long been debated, however, whether farming was brought to Anatolia similarly by a group of migrating farmers from the Fertile Crescent, or whether the local hunter-gatherers of Anatolia adopted farming practices from their neighbors.

A new study by an international team of scientists led by the Max Planck Institute for the Science of Human History and in collaboration with scientists from the United Kingdom, Turkey and Israel, published in Nature Communications, confirms existing archaeological evidence that shows that Anatolian hunter-gatherers did indeed adopt farming themselves, and the later Anatolian farmers were direct descendants of a gene-pool that remained relatively stable for over 7,000 years.

Local hunter-gatherers adopted an agricultural lifestyle

For this study, the researchers newly analyzed ancient DNA from 8 individuals, and succeeded in recovering for the first time whole-genome data from a 15,000-year-old Anatolian hunter-gatherer. This allowed the team to compare that individual's DNA to later Anatolian farmers, as well as individuals from neighboring regions, to determine how they were related. They also compared the individuals newly analyzed in the study to existing data from 587 ancient individuals and 254 present-day populations.

The researchers found that the early Anatolian farmers derived the vast majority of their ancestry (~90%) from a population related to the Anatolian hunter-gatherer in the study. "This suggests a long-term genetic stability in central Anatolia over five millennia, despite changes in climate and subsistence strategy," explains Michal Feldman of the Max Planck Institute for the Science of Human History.

"Our results provide additional, genetic support for previous archaeological evidence that suggests that Anatolia was not merely a stepping stone in a movement of early farmers from the Fertile Crescent into Europe," states Choongwon Jeong of the Max Planck Institute of the Science of Human History, co-senior author of the study. "Rather, it was a place where local hunter-gatherers adopted ideas, plants and technology that led to agricultural subsistence."

Genetic interactions with neighbors warrant further study

In addition to the long-term stability of the major component of the Anatolian ancestry, the researchers also found a pattern of interactions with their neighbors. By the time that farming had taken hold in Anatolia between 8,300-7,800 BCE, the researchers found that the local population had about a 10% genetic contribution from populations related to those living in what is today Iran and the neighboring Caucasus, with almost the entire remaining 90% coming from Anatolian hunter-gatherers. By about 7000-6000 BCE, however, the Anatolian farmers derived about 20% of their ancestry from populations related to those living in the Levant region.

"There are some large gaps, both in time and geography, in the genomes we currently have available for study," explains Johannes Krause of the Max Planck Institute for the Science of Human History, senior author on the study. "This makes it difficult to say how these more subtle genetic interactions took place - whether it was through short-term large movements of people, or more frequent but low-level interactions." The researchers hope that further research in this and neighboring regions could help to answer these questions.

farmers from Anatolia hunter-gatherers Turkey agriculture
This is the burial of a 15,000 year old Anatolian hunter-gatherer. Credit: Douglas Baird

Press release from the Max Planck Institute for the Science of Human History/Max-Planck-Institut für Menschheitsgeschichte (MPI-SHH)


genetics history prehistory Spain Iberia Iberian populations genetic history

Unique diversity of the genetic history of the Iberian Peninsula revealed by dual studies

Unique diversity of the genetic history of the Iberian Peninsula revealed by dual studies

Two studies, one looking at Iberian hunter-gatherers between 13,000 and 6,000 years ago and another looking at Iberian populations over the last 8000 years, add new resolution to our understanding of the history and prehistory of the region

Vanessa Villalba-Mouco performing aDNA labwork. Credit: Marieke S. van der Loosdrecht

An international team of researchers have analyzed ancient DNA from almost 300 individuals from the Iberian Peninsula, spanning more than 12,000 years, in two studies published today (14/03/2019) in Current Biology and Science. The first study looked at hunter-gatherers and early farmers living in Iberia between 13,000 and 6000 years ago. The second looked at individuals from the region during all time periods over the last 8000 years. Together, the two papers greatly increase our knowledge about the population history of this unique region.

The Iberian Peninsula has long been thought of as an outlier in the population history of Europe, due to its unique climate and position on the far western edge of the continent. During the last Ice Age, Iberia remained relatively warm, allowing plants and animals - and possibly people - who were forced to retreat from much of the rest of Europe to continue living there. Similarly, over the last 8000 years, Iberia's geographic location, rugged terrain, position on the Mediterranean coast and proximity to North Africa made it unique in comparison to other parts of Europe in its interactions with other regions. Two new studies, published concurrently in Current Biology and Science, analyze a total of almost 300 individuals who lived from about 13,000 to 400 years ago to give unprecedented clarity on the unique population history of the Iberian Peninsula.

Iberian hunter-gatherers show two ancient Paleolithic lineages

For the paper in Current Biology, led by researchers at the Max Planck Institute for the Science of Human History, researchers analyzed 11 hunter-gatherers and Neolithic individuals from Iberia. The oldest newly analyzed individuals are approximately 12,000 years old and were recovered from Balma Guilanyà in Spain.

Excavation work in progress at the site of Balma Guilanyà. Credit: CEPAB-UAB

Earlier evidence had shown that, after the end of the last Ice Age, western and central Europe were dominated by hunter-gatherers with ancestry associated with an approximately 14,000-year-old individual from Villabruna, Italy. Italy is thought to have been a potential refuge for humans during the last Ice Age, like Iberia. The Villabruna-related ancestry largely replaced earlier ancestry in western and central Europe related to 19,000-15,000-year-old individuals associated with what is known as the Magdalenian cultural complex.

Interestingly, the findings of the current study show that both lineages were present in Iberian individuals dating back as far as 19,000 years ago. "We can confirm the survival of an additional Paleolithic lineage that dates back to the Late Ice Age in Iberia," says Wolfgang Haak of the Max Planck Institute for the Science of Human History, senior author of the study. "This confirms the role of the Iberian Peninsula as a refuge during the Last Glacial Maximum, not only for fauna and flora but also for human populations."

This suggests that, far from being replaced by Villabruna-related individuals after the last Ice Age, hunter-gatherers in Iberia in fact already had ancestry from Magdalenian- and Villabruna-related sources. The discovery suggests an early connection between two potential refugia, resulting in a genetic ancestry that survived in later Iberian hunter-gatherers.

"The hunter-gatherers from the Iberian Peninsula carry a mix of two older types of genetic ancestry: one that dates back to the Last Glacial Maximum and was once maximized in individuals attributed to Magdalenian culture and another one that is found everywhere in western and central Europe and had replaced the Magdalenian lineage during the Early Holocene everywhere except the Iberian Peninsula," explains Vanessa Villalba-Mouco of the Max Planck Institute for the Science of Human History, first author of the study.

The researchers hope that ongoing efforts to decipher the genetic structure of late hunter-gatherer groups across Europe will help to even better understand Europe's past and, in particular, the assimilation of a Neolithic way of life brought about by expanding farmers from the Near East during the Holocene.

Ancient DNA from individuals spanning the last 8000 years helps clarify the history and prehistory of the Iberian Peninsula

The paper published in Science focuses on slightly later time periods, and traces the population history of Iberia over the last 8000 years by analyzing ancient DNA from a huge number of individuals. The study, led by Harvard Medical School and the Broad Institute and including Haak and Villalba-Mouco, analyzed 271 ancient Iberians from the Mesolithic, Neolithic, Copper Age, Bronze Age, Iron Age and historical periods. The large number of individuals allowed the team to make more detailed inferences about each time period than previously possible.

The researchers found that during the transition to a sedentary farming life-style, hunter-gatherers in Iberia contributed subtly to the genetic make-up of newly arriving farmers from the Near East. "We can see that there must have been local mixture as the Iberian farmers also carry this dual signature of hunter-gatherer ancestry unique to Iberia," explains Villalba-Mouco.

Between about 2500-2000 BC, the researchers observed the replacement of 40% of Iberia's ancestry and nearly 100% of its Y-chromosomes by people with ancestry from the Pontic Steppe, a region in what is today Ukraine and Russia. Interestingly, the findings show that in the Iron Age, "Steppe ancestry" had spread not only into Indo-European-speaking regions of Iberia but also into non-Indo-European-speaking ones, such as the region inhabited by the Basque. The researchers' analysis suggests that present-day Basques most closely resemble a typical Iberian Iron Age population, including the influx of "Steppe ancestry," but that they were not affected by subsequent genetic contributions that affected the rest of Iberia. This suggests that Basque speakers were equally affected genetically as other groups by the arrival of Steppe populations, but retained their language in any case. It was only after that time that they became relatively isolated genetically from the rest of the Iberian Peninsula.

Additionally, the researchers looked at historical periods, including times when Greek and later Roman settlements existed in Iberia. The researchers found that beginning at least in the Roman period, the ancestry of the peninsula was transformed by gene flow from North Africa and the eastern Mediterranean. They found that Greek and Roman settlements tended to be quite multiethnic, with individuals from the central and eastern Mediterranean and North Africa as well as locals, and that these interactions had lasting demographic as well as cultural impacts.

"Beyond the specific insights about Iberia, this study serves as a model for how a high-resolution ancient DNA transect continuing into historical periods can be used to provide a detailed description of the formation of present-day populations," explains Haak. "We hope that future use of similar strategies will provide equally valuable insights in other regions of the world."

genetics history prehistory Spain Iberia Iberian populations genetic history Iberian Peninsula
Cueva de Chaves site. Credit: Museo de Huesca

Press release from the Max Planck Institute for the Science of Human History/Max-Planck-Institut für Menschheitsgeschichte (MPI-SHH)


Homo floresiensis rat rats Rattus hainaldi hobbit

Changes in rat size reveal habitat of 'Hobbit' hominin

Changes in rat size reveal habitat of 'Hobbit' hominin

A new glimpse into the shifting ecology of Homo floresiensis

Veatch looks at piles of sediment excavated from Luang Bua as it is being wet sieved using the irrigation system of a rice paddy near the cave site. Credit: Photo by Hanneke Meijer.

A study of rat body sizes shifting over time gives a glimpse into the habitat of the mysterious hominin Homo floresiensis -- nicknamed the "Hobbit" due to its diminutive stature.

The Journal of Human Evolution is publishing the study, based on an analysis of thousands of rodent bones, mainly fore- and hind-limbs, from an Indonesian cave where H. floresiensis was discovered in 2003. The results indicate that the local habitat was mostly open grasslands more than 100,000 years ago, but began shifting rapidly to a more closed environment 60,000 years ago.

"Our paper is the first that we know of to use the leg bones of rats in this way to interpret ecological change through time, and it provides new evidence for the local environment during the time of Homo Floresiensis," says Elizabeth Grace Veatch, a PhD candidate at Emory University and a first author of the study.

H. floresiensis stood only about 3 feet 6 inches tall and was known to have lived about 190,000 to 50,000 years ago on the oceanic island of Flores in eastern Indonesia. The tiny hominin shared the island with animals that could have come from the pages of a Tolkien novel, including giant Komodo dragons, six-foot-tall storks, vultures with a six-foot wingspan, and pygmy Stegodons -- herbivores that looked like small elephants with swooping, oversized tusks.

This is a graphic image of the Liang Bua rat species used in the study. Credit: image from the research paper

It was the rats, however, that most interested Veatch.

Murids, as the rat family is known, are more taxonomically diverse than any other mammal group and are found in nearly every part of the world. "They exhibit an incredible range of behaviors occupying many different ecological niches," Veatch says. "And because small mammals are typically sensitive to ecological shifts, they can tell you a lot about what's going on in an environment."

The study was based on remains recovered from the limestone cave known as Liang Bua, where partial skeletons of H. floresiensis have been found, along with stone tools and the remains of animals -- most of them rats. In fact, out of the 275,000 animal bones identified in the cave so far, 80 percent of them are from rodents.

Veatch came to Emory to work with paleoanthropologist Jessica Thompson, a leading expert in using taphonomy -- the study of what happens to bones after an organism dies -- to learn more about the evolution of the human diet. Although Thompson has now moved to Yale University, she continues to mentor Veatch in her graduate studies at Emory.

Veatch became part of the Liang Bua project while doing an internship with the Human Origins Program of the Smithsonian Institution's National Museum of Natural History. Her mentor there was paleoanthropologist Matthew Tocheri (now with Lakehead University in Ontario) who shares first-authorship of the current paper with Veatch.

"Matthew asked me if I wanted to analyze some rat bones and I said, 'Sure,'" Veatch recalls. "I had no idea what I was getting into."

The study encompassed about 10,000 of the Liang Bua rat bones. The remains spanned five species with distinct sizes, from the mouse-sized Rattus hainaldi up to the housecat-sized Papagomys armandvillei -- commonly known as the Flores giant rat. After categorizing the bones, the researchers could then directly link them to both species and environmental types.

While rats can adjust to new environments, the morphologies of different species tend to be adaptive to their preferred environment. For example, the habitat of the medium-sized Komodomys rintjanus, included in the study, is primarily open grasslands intermittent with patches of forest. In contrast, the tiny R. hainaldi and the giant P. armandvillei both prefer more closed or semi-closed forested habitats.

Tracking the relative abundances of the different rat species over time indicated that the local ecology was mostly open grassland 100,000 years ago, transitioning to a more-closed, forested habitat around 60,000 years ago. That is around the same time that skeletal elements belonging to Homo floresiensis, the pygmy Stegodon, giant storks, vulture and Komodo dragons disappear from Liang Bua.

"The evidence suggests that Homo floresiensis may have preferred more open habitats where they may have been a part of this scavenging guild of Stegodons, storks and vultures," Veatch says. "We think that when the habitat changed, becoming more forested, Homo floresiensis probably left the Liang Bua area, tracking these animals to more open habitats elsewhere on the island."

Many more mysteries remain regarding H. floresiensis, Veatch says, and the Liang Bua rat bones may help solve some of them.

Homo floresiensis rat rats Rattus hainaldi hobbit hominin
At the Liang Bua cave site, paleoanthropologist Matthew Tocheri, left, measures a modern giant rat with the assistance of Bonefasius Sagut. At right is a reconstruction of Homo floresiensis carrying a giant rat, by paleo artist Peter Schouten. 

One key question is whether H. floresiensis hunted small game.

"Our early ancestors adapted to consuming large amounts of big game through hunting or scavenging -- or both," Veatch says. "Big game undoubtedly became a critical food source, resulting in numerous social and physiological adaptations, including social cooperation and brain expansion. It's much less known, however, what role small-game hunting may have played in our early evolution -- if any at all."

Liang Bua, she says, offers an ideal opportunity to study what a small-brained hominin, like H. floresiensis, might hunt if it had both sources of big game, like the Stegodon, and small game, like the giant Flores rat and other rat species.

Veatch is conducting field studies at the Liang Bua site, including running experiments to determine how difficult it would be to capture wild Flores rats. She is also doing research at the Pusat Penelitian Arkeologi Nasional (ARKENAS) Museum in the Indonesian capital of Jakarta where many of the bones from the cave site are now stored. She is analyzing a large sample of the bones to determine if any have cut marks -- indicating butchering with tools -- or pitted marks that would indicate they were digested by owls or other raptors that may have deposited them in the cave.

"In Indonesia, my nickname is Miss Tikus, which means 'Miss Rat,'" Veatch says. "I'm perfectly fine with that because rats are really intelligent and extraordinary animals. We see them through the entire sequence in the archeology of Liang Bua and we will continue to use them in future studies to learn more about what went on in the cave."

###

Co-authors of the current paper include Thomas Sutikna, E. Wahyu Saptomo and Jamiko, who are all from ARKENAS and the University of Wollongong in Australia; Kate McGrath from the University of Bordeaux, France; and Kristofer Helgen from the University of Adelaide in Australia.

 

Press release from Emory Health Sciences


Prehistoric Britons rack up food miles for feasts near Stonehenge

Prehistoric Britons rack up food miles for feasts near Stonehenge

Landmark study reveals the monumental distances traveled for national mass gatherings

 

Archaeologists have unearthed evidence of the earliest large-scale celebrations in Britain - with people and animals travelling hundreds of miles for prehistoric feasting rituals.

The study, led by Dr Richard Madgwick of Cardiff University, is the most comprehensive to date and examined the bones of 131 pigs, the prime feasting animals, from four Late Neolithic (c. 2800-2400BC) complexes. Serving the world-famous monuments of Stonehenge and Avebury, the four sites - Durrington Walls, Marden, Mount Pleasant and West Kennet Palisade Enclosures - hosted the very first pan-British events, feasts that drew people and animals from across Britain.

The results show pig bones excavated from these sites were from animals raised as far away as Scotland, North East England and West Wales, as well as numerous other locations across the British Isles. The researchers believe it may have been important for those attending to contribute animals raised locally at their homes.

Before now, the origins of people that took part in rituals at these megalithic monuments and the extent of the population's movements at the time have been long-standing enigmas in British prehistory.

Dr Richard Madgwick, of the School of History, Archaeology and Religion, said: "This study demonstrates a scale of movement and level of social complexity not previously appreciated."

"These gatherings could be seen as the first united cultural events of our island, with people from all corners of Britain descending on the areas around Stonehenge to feast on food that had been specially reared and transported from their homes."

Representing great feats of engineering and labour mobilisation, the Neolithic henge complexes of southern Britain were the focal point for great gatherings in the third millennium BC. Pigs were the prime animal used in feasting and they provide the best indication of where the people who feasted at these sites came from as almost no human remains have been recovered.

Using isotope analysis, which identifies chemical signals from the food and water that animals have consumed, the researchers were able to determine geographical areas where the pigs were raised. The study offers the most detailed picture yet of the degree of mobility across Britain at the time of Stonehenge.

Dr Madgwick said: "Arguably the most startling finding is the efforts that participants invested in contributing pigs that they themselves had raised. Procuring them in the vicinity of the feasting sites would have been relatively easy.

"Pigs are not nearly as well-suited to movement over distance as cattle and transporting them, either slaughtered or on the hoof, over hundreds or even tens of kilometres, would have required a monumental effort.

"This suggests that prescribed contributions were required and that rules dictated that offered pigs must be raised by the feasting participants, accompanying them on their journey, rather than being acquired locally."

Dr Madgwick conducted the research in collaboration with colleagues at the School of Earth and Ocean Sciences at Cardiff University, along with scientists from the NERC Isotope Geosciences Laboratory at the British Geological Survey, University of Sheffield and University College London. The project was funded by the British Academy as part of a post-doctoral fellowship and was supported by a NERC Isotope Geosciences Facility Steering Committee grant.

The study, 'Multi-isotope analysis reveals that feasts in the Stonehenge environs and across Wessex drew people and animals from throughout Britain', funded by the British Academy and NERC is published in Science Advances.

Stonehenge. Foto di @thegarethwiscombe, CC BY 2.0

Press release from Cardiff University.


From Stone Age chips to microchips: How tiny tools may have made us human

From Stone Age chips to microchips: How tiny tools may have made us human

The technology of miniaturization set hominins apart from other primates

The iconic, tear-drop shaped hand axe, which filled a human palm, required a large toolkit to produce (left), in contrast to a toolkit for tiny flakes. Credit: Emory University

Anthropologists have long made the case that tool-making is one of the key behaviors that separated our human ancestors from other primates. A new paper, however, argues that it was not tool-making that set hominins apart -- it was the miniaturization of tools.

Just as tiny transistors transformed telecommunications a few decades ago, and scientists are now challenged to make them even smaller, our Stone Age ancestors felt the urge to make tiny tools. "It's a need that we've been perennially faced with and driven by," says Justin Pargeter, an anthropologist at Emory University and lead author of the paper. "Miniaturization is the thing that we do."

Stone Age miniaturization stone tools prehistory
Going small may have helped some humans survive the last period of rapid climate change, 17,000 years ago, says Emory anthropologist Justin Pargeter. Credit: Emory University

The journal Evolutionary Anthropology is publishing the paper -- the first comprehensive overview of prehistoric tool miniaturization. It proposes that miniaturization is a central tendency in hominin technologies going back at least 2.6 million years.

"When other apes used stone tools, they chose to go big and stayed in the forests where they evolved," says co-author John Shea, professor of anthropology at Stony Brook University. "Hominins chose to go small, went everywhere, and transformed otherwise hostile habitats to suit our changing needs."

The paper reviews how stone flakes less than an inch in length -- used for piercing, cutting and scraping -- pop up in the archeological record at sites on every continent, going back to some of the earliest known stone tool assemblages. These small stone flakes, Pargeter says, were like the disposable razor blades or paperclips of today -- pervasive, easy to make and easily replaced.

He identifies three inflection points for miniaturization in hominin evolution. The first spike occurred around two million years ago, driven by our ancestors' increasing dependence on stone flakes in place of nails and teeth for cutting, slicing and piercing tasks. A second spike occurred sometime after 100,000 years ago with the development of high-speed weaponry, such as the bow and arrow, which required light-weight stone inserts. A third spike in miniaturization occurred about 17,000 years ago. The last Ice Age was ending, forcing some humans to adapt to rapid climate change, rising sea levels and increased population densities. These changes increased the need to conserve resources, including the rocks and minerals needed to make tools.

A native of South Africa, Pargeter co-directs field work in that country along its rugged and remote Indian Ocean coastline and nearby inland mountains. He is also a post-doctoral fellow in Emory University's Center for Mind, Brain and Culture and the Department of Anthropology's Paleolithic Technology Laboratory. The lab members actually make stone tools to better understand how our ancestors learned these skills, and how that process shaped our evolution. The lab's director, Dietrich Stout, focuses on hand axes, dating back more than 500,000 years. These larger tools are considered a turning point in human biological and cognitive evolution, due to the complexity involved in making them.

Pargeter's work on tiny tools adds another facet to the investigation of human evolution. "He's exploring what may have led to the compulsion to produce these tiny instruments -- essentially the relationship between the tools and the human body, brain and the probable uses of the tools," Stout says.

When looking for a PhD thesis topic, Pargeter first focused on collections of larger implements, considered typical of the Stone Age tool kit. He pored over artifacts from a South African site called Boomplaas that were being held in storage at the Iziko Museum in Cape Town. As he rummaged through a bag labelled as waste -- containing small flakes thought to be left over from making larger tools -- something caught his eye. A sliver of crystal quartz looked like it had been shaped using a highly technical method called pressure flaking.

"It was diminutive, about the size of a small raisin, and weighed less than half a penny," he recalls. "You could literally blow it off your finger."

Pargeter examined the flake under a magnifying glass. He noticed it had a distinctive, stair-step fracture on its tip that previous experimental research showed to be associated with damage caused in hunting.

"It suddenly occurred to me that archeologists may have missed a major component of our stone tool record," Pargeter says. "In our desire to make 'big' discoveries we may have overlooked tiny, but important, details. A whole technology could lay hidden behind our methods, relegated to bags considered waste material."

So how to interpret the use of a tool so tiny that you could easily blow it off your finger?

Pargeter began thinking of this question in terms of the age of the flake -- about 17,000 years -- and the environment at the time. The last Ice Age was ending and massive melting of ice at the poles caused the global sea-level to rise. In parts of South Africa, the rising oceans swallowed an area the size of Ireland. As the coastal marshes and grasslands disappeared -- along with much of the game and aquatic life -- the hunter-gatherers living there fled inland to sites like Boomplaas, currently located about 80 kilometers inland. The mountains around Boomplaas provided permanent springs and other dependable freshwater sources.

The climate, however, was less predictable, with sudden shifts in temperature and rainfall. Vegetation was shifting dramatically, temperatures were rising and large mammals were increasingly scarce. Archaeology from Boomplaas shows that people ate small game like hares and tortoises. These small animals would have been easy to catch, but they provided limited nutritional packages.

"These are low-reward food sources, indicating a foraging stress signal," Pargeter says. "Boomplaas might have even served as a type of refugee camp, with groups of hunter-gatherers moving away from the coast, trying to survive in marginal environments as resources rapidly depleted and climate change ratcheted up."

Arrow points a little less than an inch across were already in the archaeological literature, but the Boomplaas crystal quartz flake was half that size. In order to bring down an animal, Pargeter hypothesized, the Boomplaas flake would need poison on its tip -- derived either from plants or insects -- and a high-speed delivery system, such as a bow and arrow.

The tiny crystal flake, from a site in South Africa called Boomplaas, that sparked Justin Pargeter to investigate Stone Age miniaturization. Credit: Justin Pargeter

Pargeter used his own extensive knowledge of prehistoric tool-making and archaeology to hypothesize that the tiny flake could have been hafted, using a plant-based resin, onto a link shaft, also likely made of a plant-based material, such as a reed. That link shaft, about the length of a finger, would in turn fit onto a light arrow shaft.

"The link shaft goes into the animal, sacrificing the small blade, but the arrow shaft pops out so you can retain this more costly component," he says. "Our ancestors were masters of aerodynamics and acted like engineers, rather than what we think of as 'cave people.' They built redundancy into their technological systems, allowing them to easily repair their tools and to reduce the impact of errors."

Our ancestors were also connoisseurs of the type of fine-grained rocks needed for tool-making.

Supplies of such vital toolmaking raw materials, however, were likely diminished as the rising oceans consumed land and people became more crowded together, driving them to more carefully conserve what they could find on the landscape.

As paleoanthropologists are faced with more than three million years of hominin "stuff," one of the perennial questions they keep seeking to answer is, what makes us humans unique? "We've typically said that tool use makes us human, but that's kind of buckled under," Pargeter says, as evidence of tool use by other animals accumulates.

Macaques, for example, use rocks to smash apart oysters. Chimpanzees use rocks as hammers and anvils to crack nuts and they modify sticks to dig and fish for termites. These tools, however, are large. "The hands of other primates are not evolved for repeated fine manipulation in high-force tasks," Pargeter says. "We've evolved a unique precision grip that ratchets up our ability for miniaturized technology."

Humans are also the masters of dispersing into novel environments, unlike other primates that remained in the landscapes of their ancestors. "Smaller tools are the choice of technology for a mobile, dispersing population," Pargeter says. "When Homo sapiens left Africa they weren't carrying bulky hand axes, but bows and arrows and smaller stone implements."

 

Press release from Emory Health Sciences


Paleolithic rock art Montsant valley Spain

Researchers find a piece of Palaeolithic art featuring birds and humans

Researchers find a piece of Palaeolithic art featuring birds and humans

An exceptional milestone in European Palaeolithic rock art

Paleolithic rock art Montsant valley Spain Hort de la Bequera
Image of the findings with a tracing of the engraved figures on the piece. Credit: UNIVERSITY OF BARCELONA

It is not very common to find representations of scenes instead of individual figures in Palaeolithic art, but it is even harder for these figures to be birds instead of mammals such as goats, deer or horses. So far, historians have only found three scenes of Palaeolithic art featuring humans and birds in Europe.

Now, an article published in the journal L'Anthropologie tells how University of Barcelona researchers found -in the site of Hort de la Bequera (Margalef de Montsant, Priorat)-, an artistic piece from 12,500 years ago in which humans and birds try to interact in a pictorial scene with exceptional traits: figures seem to star a narration on hunting and motherhood. Regarding the Catalan context in particular, this is an important finding regarding the few pieces of Palaeolithic art in Catalonia and it places this territory within the stream of artistic production of the upper Palaeolithic in the Mediterranean.

The piece they found is a 30-centimeter long limestone which shows two human figures and two birds, which the researchers identified as cranes. Since they found the piece in 2011, they underwent all cleaning, restoration and 3D copying procedures to study it in detail. Those figures were engraved in the stone board with a flint tool so that they created an organized composition compared to the other pieces of the same period.

"This is one of the few found scenes so far which suggest the birth of a narrative art in Europe, and this theme is unique, since it combines an image of hunting and a motherhood one: a birth with its young one", says the first signer of the article, ICREA researcher and lecturer at the UB Inés Domingo. "In the represented scene the birds catch the attention, they are copied or chased by two human figures", continues Domingo. "We do not know the meaning of the scene for prehistoric peoples, but what it says is that not only they were regarded as preys but also as a symbol for European Palaeolithic societies", she continues.

"We do not doubt this is an exceptional milestone in European Palaeolithic rock art due its singularity, its excellent conservation and the chances to study it within a general context of excavation", say the authors of the article; members of the Prehistoric Studies and Research Seminar (SERP). Apart from Domingo, other signers are the UB lecturers of Prehistory Pilar García Argüelles, Jordi Nadal, directors of the excavation in Host de la Boquera, Professor Josep Maria Fullola, director of SERP, and José L. Lerma and the researcher Miriam Cabrelles, from Universitat Politècnica de València, who worked on the 3D reproduction of this piece.

Palaeolithic art in Montsant valley

The other sites in Europe researchers had found so far with human and bird figures are rock paintings in the site of Lascauz, a perforated baton in Abri Mege (Teyjat, Dordogne), and the Great Hunter plaque in the site of Gönnersdorf (Germany).

SERP researchers have been excavating in the valley of Montsant since 1979, an exceptional area regarding findings of this period of the late upper Palaeolithic. In particular, excavations have taken place in Host de la Boquera since 1998 and it provided a great amount of flint tools and structure such as rooms for a fireplace.

The director of the excavation, Pilar García Argüelles notes that "the findings of the engraved scene are exceptional, and proves the importance of the site and the area regarding Palaeolithic art in the peninsular north-east area; where we can find nearby the only Palaeolithic cave engraving in Catalonia, the deer in the cave of Taverna (Margalef de Montsant), and about 40 kilometres away there is Molí del Salt (Vimbodí), with an interesting series of stone blocks with engraved animals and a representation of huts".

The first to identify the engraving was the co-director of the excavation, Jordi Nadal, who remembers that moment with excitement: "Since the first moment I was aware of the importance of this finding, of its uniqueness; these things do not happen very often, this is seeing a figure that has been forgotten and buried for 12,500 years".

 

Press release from the Universitat de Barcelona


Proofs of parallel evolution between cognition, tool development, and social complexity

Proofs of parallel evolution between cognition, tool development, and social complexity

A study analyzes the selective attention processes that determine how we explore and interact with our environment

Proofs of parallel evolution between cognition, tool development, and social complexity Galician ceramics Iberia prehistory
Main ceramics analyzed in the experiments and heatmap of the visual fixations in each one of them. The images are organized, from left to right, in chronological order from oldest to most recent. Following time, the fixations direction changes from horizontal to vertical. Credit: CSIC

Researchers examined the visual response of 113 individuals when observing prehistoric ceramics belonging to different styles and societies. The ceramics analysed cover 4.000 years (from 4.000 B.C. to the change of era) of Galician prehistory (north-west Iberia), and are representative of ceramic styles, such as bell-beaker pottery, found throughout Europe. The results indicate that the visual behaviour follows the same evolutionary trends as those that drive the evolution of the complex societies that built these archaeological materialities.

"We hypothesised that culture and social life influence cognition in a highly stereotyped fashion. Eye movements are the most objective proof of a parallel evolution between the cognitive process, material development and changes in social complexity", explains CSIC researcher Felipe Criado-Boado, from the Institute of Heritage Sciences, in Santiago de Compostela. This study is part of the field of neuroarchaeology, a new scientific field that combines neuroscience with human palaeontology, archaeology, and other social and human sciences.

"The visual prominence of each ceramic style produces a distinct visual response. Prehistoric ceramics comprise an important part of the material world that surrounded the individuals of that time. This is why an analysis of this kind is not only feasible, but also provides very significant results", adds Criado-Boado.

Luis M. Martínez, a researcher from the Institute of Neurosciences, in Alicante, explains that, "in our brain there are neural circuits, or maps, that represent our personal and peripersonal space. These circuits determine the way in which we relate socially, and also with the world around us. With experiments of this kind, we are demonstrating that these representations are modified by the use and making of tools and other cultural artefacts; what we are discovering is that they are quickly incorporated into these neural maps, becoming part of our body schema as if they were an extension of it. These experiments unequivocally demonstrate that there is a very close interaction between cultural changes and brain plasticity, which provides a new perspective on how the brain governs for the transmission of cultural values, beliefs and customs".

The results of this research indicate that the human visual system actively internalises the object it observes, which would demonstrate that there is a perceptual engagement between the observers and the material structures in their environment. "This is why perception cannot be separated from form. Seen from this perspective, it could be proposed that the shape of objects (pottery, in this case) and the pattern of visual exploration they produce have changed over history, and are connected with behaviour in the same way as they are with the social realm, including social complexity," says Criado-Boado.

Another of the conclusions of this study is that technology is an important factor in the mental aspects of human life. This offers a new perspective that helps to explain the processes of innovation and technological change that take place in all historical periods, including the present day. "It is believed that by 2020 there will be 100 billion sensors around the world capturing information of all kinds and processing it digitally, all connected to each other and functioning like an enormous human mind. If this prediction is fulfilled, research in the field of cognitive processes and material culture throughout history may be useful for the future, since it can show how humans rely on images that symmetrically help them to shape a collective consciousness of the world", concludes the researcher.

Read more


Campo Laborde Pampas megafauna extinction giant ground sloth

Evidence for human involvement in extinction of megafauna in the late Pleistocene

Evidence for human involvement in extinction of megafauna in the late Pleistocene

Campo Laborde: A Late Pleistocene giant ground sloth kill and butchering site in the Pampas

Campo Laborde Pampas megafauna extinction giant ground sloth
Lithic tool associated with giant ground sloth bones. Credit: Gustavo Politis and Pablo Messineo

By re-dating giant ground sloth remains found in the Argentinian Pampas region using more advanced technology, scientists say they have provided evidence that humans hunted and butchered this animal near a swamp during the end of the Pleistocene. Based on their radiocarbon dates of this specimen, the authors say that their report challenges the popular hypothesis that megamammals from South America survived well into the Holocene in the Pampas, instead suggesting they took their last breaths in the Pleistocene. Loss of up to 90% of large animal species on ice-free continents occurred during the end of the Pleistocene, and many megafauna went extinct. To date, studies have suggested that humans and/or climate-driven events could be to blame for megafauna loss, but the causes and dynamics of megafauna extinction are hard to determine, and direct evidence of human predation on megafauna is scarce. The Argentinian archeological site Campo Laborde has produced many megafauna fossils, but accurate radiocarbon dating has been difficult on these bones because the fossils have very little collagen, making it hard to extract. Dating is also challenging because the collagen is heavily contaminated with sedimentary organic matter. To overcome this contamination, Gustavo G. Politis and colleagues thought to apply XAD purification chemistry, which can isolate the amino acids in a bone's collagen, resulting in a more accurate radiocarbon date, they say. Only one bone from a giant ground sloth found at Campo Laborde contained collagen. This specimen was first dated in 2007 as being around 9,730 years of age (pegging it to the Holocene, which began around 11,650 years ago). Using accelerator mass spectrometry to radiocarbon date the amino acids of the specimen, Politis determined that the giant ground sloth bone better dated to around 10,570 years of age, plus or minus 170 years. According to the authors, contaminated collagen was the reason for the previous "younger" (Holocene) dates. In addition to the previously discovered lithic artifacts that were found around the giant ground slot and dated to around 11,800 and 10,000 years before present, this study "solidly dates" the killing and exploitation of the giant ground sloth to the late Pleistocene and does not support extinct megamammals surviving into the Holocene at Campo Laborde, the authors say.

Press release by AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE

 


hominins fossils Ardipithecus ramidis Afar Regional State Ethiopia

New findings shed light on origin of upright walking in human ancestors

New findings shed light on origin of upright walking in human ancestors

4.5 million-year old fossil shows evidence of greater reliance on bipedalism than previously suggested

 

The oldest distinguishing feature between humans and our ape cousins is our ability to walk on two legs - a trait known as bipedalism. Among mammals, only humans and our ancestors perform this atypical balancing act. New research led by a Case Western Reserve University School of Medicine professor of anatomy provides evidence for greater reliance on terrestrial bipedalism by a human ancestor than previously suggested in the ancient fossil record.

Scott W. Simpson, PhD, led an analysis of a 4.5 million-year-old fragmentary female skeleton of the human ancestor Ardipithecus ramidus that was discovered in the Gona Project study area in the Afar Regional State of Ethiopia.

The newly analyzed fossils document a greater, but far from perfect, adaptation to bipedalism in the Ar. ramidus ankle and hallux (big toe) than previously recognized. "Our research shows that while Ardipithecus was a lousy biped, she was somewhat better than we thought before," said Simpson.

Fossils of this age are rare and represent a poorly known period of human evolution. By documenting more fully the function of the hip, ankle, and foot in Ardipithecus locomotion, Simpson's analysis helps illuminate current understanding of the timing, context, and anatomical details of ancient upright walking.

Previous studies of other Ardipithecus fossils showed that it was capable of terrestrial bipedalism as well as being able to clamber in trees, but lacked the anatomical specializations seen in the Gona fossil examined by Simpson. The new analysis, published in the Journal of Human Evolution, thus points to a diversity of adaptations during the transition to how modern humans walk today. "The fact that Ardipithecus could both walk upright, albeit imperfectly, and scurry in trees marks it out as a pivotal transitional figure in our human lineage," said Simpson.

Key to the adaptation of bipedality are changes in the lower limbs. For example, unlike monkeys and apes, the human big toe is parallel with the other toes, allowing the foot to function as a propulsive lever when walking. While Ardipithecus had an offset grasping big toe useful for climbing in trees, Simpson's analysis shows that it also used its big toe to help propel it forward, demonstrating a mixed, transitional adaptation to terrestrial bipedalism.

Specifically, Simpson looked at the area of the joints between the arch of the foot and the big toe, enabling him to reconstruct the range of motion of the foot. While joint cartilage no longer remains for the Ardipithecus fossil, the surface of the bone has a characteristic texture which shows that it had once been covered by cartilage. "This evidence for cartilage shows that the big toe was used in a more human-like manner to push off," said Simpson. "It is a foot in transition, one that shows primitive, tree-climbing physical characteristics but one that also features a more human-like use of the foot for upright walking." Additionally, when chimpanzees stand, their knees are "outside" the ankle, i.e., they are bow-legged. When humans stand, the knees are directly above the ankle - which Simpson found was also true for the Ardipithecus fossil.

The Gona Project has conducted continuous field research since 1999. The study area is located in the Afar Depression portion of the eastern Africa rift and its fossil-rich deposits span the last 6.3 million years. Gona is best known as documenting the earliest evidence of the Oldowan stone tool technology. The first Ardipithecus ramidus fossils at Gona were discovered in 1999 and described in the journal Nature in 2005. Gona has also documented one of the earliest known human fossil ancestors - dated to 6.3 million years ago. The Gona Project is co-directed by Sileshi Semaw, PhD, a research scientist with the CENIEH research center in Burgos, Spain, and Michael Rogers, PhD, of Southern Connecticut State University. The geological and contextual research for the current research was led by Naomi Levin, PhD, of the University of Michigan, and Jay Quade, PhD, of the University of Arizona.

hominins fossils bipedalism Ardipithecus ramidis Afar Regional State Ethiopia
This is a fossil hominin talus from site GWM67 (2005) at the time of its discovery. Credits: Case Western Reserve University School of Medicine

###

This research was made possible by use of the human and ape skeletal collections housed at the Laboratory of Physical Anthropology, Cleveland Museum of Natural History. Major financial support was provided by the L.S.B. Leakey Foundation, Spain's Ministerio de Economia, Industria y Competitividad, Marie Curie EU Integration Grant, U.S. National Science Foundation, Case Western Reserve University, the National Geographic Society, and the Wenner-Gren Foundation.

Simpson, S., et al. "Ardipithecus ramidus postcrania from the Gona Project area, Afar Regional State, Ethiopia." Journal of Human Evolution. DOI: 10.1016/j.jhevol.2018.12.005

For more information about Case Western Reserve University School of Medicine, please visit case.edu/medicine.

Press release from Case Western Reserve University