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My Ex-Girlfriend Always Said I Was a Neanderthal – She Was Right
Neanderthals lived in Europe and parts of Asia until they became extinct about 40,000 years ago. For more than a hundred years, paleontologists and anthropologists have been striving to uncover the evolutionary relationship of Neanderthals to modern humans. Svante Paabo, Department Director of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany (shown here with a reconstructed Neanderthal skull) painstakingly decoded the Neanderthal genome for over 20 years and then compared it with the Homo Sapiens genome. In the process, his team of researchers explored a series of questions: What does the Neanderthal genome divulge about modern humans, and how do we differ from each other? Which human capacities and characteristics hark back to Neanderthals? Why did our closest relative become extinct? One thing is now certain -- the Neanderthal and modern humans interbred -- and today we are far more closely related than we previously believed. Recently, Stanford University scientists have found that interbreeding between Neanderthals and modern humans may have given modern humans some important genetic tools needed to survive – One being the ability to combat viral infections. (Credit: Ker Than, Stanford University) (Image Credit: Frank Vinken, Max Planck Institute for Evolutionary Anthropology - Leipzig)
My Ex-Girlfriend Always Said I Was a Neanderthal – She Was Right
Neanderthals mysteriously disappeared about 40,000 years ago, but before vanishing they interbred with groups of humans that were just beginning their global spread out of Africa, into the Fertile Crescent of the Middle East, and then on to Europe and other parts of Asia. As a result of this ancient intermixing, many modern Europeans and Asians today harbor about 2 to 3 percent of Neanderthal DNA in their genomes.
Curiously, some snippets of Neanderthal DNA pop up more often in modern human populations than others, leading scientists to wonder if their spread was propelled by chance or whether these frequently occurring genes confer some functional advantage.
Stanford scientists have now found compelling evidence for the latter. “Our research shows that a substantial number of frequently occurring Neanderthal DNA snippets were adaptive for a very cool reason,” said evolutionary biologist Dmitri Petrov, Professor in the School of Humanities and Sciences at Stanford University. “Neanderthal genes likely gave us some protection against viruses that our ancestors encountered when they left Africa.”
When first contact occurred between the two species, Neanderthals had been living outside of Africa for hundreds of thousands of years, giving their immune systems ample time to evolve defenses against infectious viruses in Europe and Asia. Our newly emigrated ancestors, by comparison, would have been much more vulnerable. “It made much more sense for modern humans to just borrow the already adapted genetic defenses from Neanderthals rather than wait for their own adaptive mutations to develop, which would have taken much more time,” said David Enard, a former postdoctoral fellow in Petrov’s lab.
Petrov and Enard said their findings are consistent with a “poison-antidote” model of gene swapping between two species. In this scenario, Neanderthals bequeathed to modern humans not only infectious viruses but also the genetic tools to combat the invaders.
“Modern humans and Neanderthals are so closely related that it really wasn’t much of a genetic barrier for these viruses to jump,” said Enard, who is now an assistant professor at the University of Arizona. “But that closeness also meant that Neanderthals could pass on protections against those viruses to us.”
In their new study, the scientists show that the genetic defenses that Neanderthals passed to us were against RNA viruses, which encode their genes with RNA, a molecule that’s chemically similar to DNA.
The scientists reached their conclusions after compiling a list of more than 4500 genes in modern humans that are known to interact in some way with viruses. Enard then checked his list against a database of sequenced Neanderthal DNA and identified 152 fragments of those genes from modern humans that were also present in Neanderthals.
The scientists showed that in modern humans, the 152 genes we inherited from Neanderthals interact with modern day HIV, influenza A, and hepatitis C – all types of RNA virus. From this, Enard and Petrov concluded that these genes helped our ancestors fend off ancient RNA viruses that they encountered upon leaving Africa.
Interestingly, the Neanderthal genes they identified are present only in modern Europeans, suggesting that different viruses influenced genetic swapping between Neanderthals and the ancient ancestors of today’s Asians. This makes sense, Enard said, since interbreeding between Neanderthals and modern humans is thought to have occurred multiple times and in multiple locales throughout prehistory, and different viruses were likely involved in each instance.
In addition to offering a new perspective on interbreeding between Neanderthals and humans, the new findings also demonstrate that it’s possible to comb through a species’ genome and find evidence of ancient diseases that once afflicted it – even when the viruses responsible for those diseases are long gone. This technique would work especially well for RNA viruses, whose RNA-based genomes are more frail than their DNA counterparts, Enard says.
“It’s similar to paleontology,” he added. “You can find hints of dinosaurs in different ways. Sometimes you’ll discover actual bones, but sometimes you find only footprints in fossilized mud. Our method is similarly indirect: Because we know which genes interact with which viruses, we can infer the types of viruses responsible for ancient disease outbreaks.”
The Neanderthal Genome
The Neanderthal, the enigmatic Stone Age man who appears to have vanished without a trace 40,000 years ago, lives on in us modern humans. Researchers working with Svante Paabo at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, decoded the Neanderthal genome for over 20 years and compared it with the Homo Sapiens genome. In the process, the researchers explored a series of questions: What does the Neanderthal genome divulge about modern humans, and how do we differ from each other? Which human capacities and characteristics hark back to Neanderthals? Why did our closest relative become extinct?
One thing is now certain: the Neanderthal and modern man mixed -- and we are far more closely related than we previously believed. An initial comparison of the two genome sequences has brought some exciting discoveries to light. Contrary to the assumption of many researchers, it would appear that some Neanderthals and early modern humans interbred. According to the researchers' calculations, two to three percent of the DNA of many humans living today originated from the Neanderthal.
In 2010, the Researchers produced the first whole genome sequence of the 3 billion letters in the Neanderthal genome, and the initial analysis suggested that the DNA in the genome of
present-day humans outside of Africa originated in Neanderthals or in Neanderthals' ancestors.
The current fossil record suggests that Neanderthals, or Homo Neanderthalensis, diverged from the line that led to present-day humans, or Homo Sapiens, some 400,000 years ago in Africa. Neanderthals migrated north into Eurasia, where they became a geographically isolated group that evolved independently from the line that became modern humans in Africa. They lived in Europe and western Asia, as far east as southern Siberia and as far south as the Middle East.
Approximately 40,000 years ago, Neanderthals disappeared. That makes them the most recent,
extinct relative of modern humans, as both Neanderthals and humans share a common ancestor from about 800,000 years ago. In comparison, Chimpanzees diverged from the original primate line some 5 million to 7 million years ago.
The researchers compared DNA samples from the bones of three female Neanderthals who lived some 40,000 years ago in Europe to samples from five present-day humans from China, France, Papua New Guinea, southern Africa, and western Africa. This provided the first genome-wide look at the similarities and differences of the closest evolutionary relative to humans, and maybe even identifying, for the first time, genetic variations that gave rise to modern humans.
"This sequencing project is a technological tour de force," said Director Eric D. Green. "You must appreciate that this international team has produced a draft sequence of a genome that existed 400 centuries ago. Their analysis shows the power of comparative genomics and brings new insights to our understanding of human evolution."
The Neanderthal DNA was removed from bones discovered at Vindija Cave in Croatia and prepared in the clean room facility of the Max Planck Institute for Evolutionary Anthropology to prevent contamination with contemporary DNA. The Max Planck group was led by their Department of Evolutionary Genetics Director Svante Paabo Ph.D. -- a well-known pioneer in Neanderthal genome research. The team deposited the Neanderthal genome sequence in the publicly available NIH genetic sequence database GenBank.
To understand the genomic differences between present-day humans and Neanderthals, the
researchers compared subtle differences in the Neanderthal genome to the genomes found in DNA from the five people, as well as to chimpanzee DNA. An analysis of the genetic variation showed that Neanderthal DNA is 99.7 percent identical to present-day human DNA, and 98.8 percent identical to chimpanzee DNA. Present-day human DNA is also 98.8 percent identical to chimpanzee.
"The genomic calculations showed good correlation with the fossil record," said Jim Mullikin, a computational geneticist. "According to our results, the ancestors of Neanderthals and modern humans went their separate ways about 400,000 years ago."
The comparison between Neanderthal and present-day human genomes produced a catalog of genetic differences that allow the researchers to identify features that are unique to present-day humans. For example, the catalog includes differences in genes that code for functional elements, such as proteins, in which the Neanderthal versions are more like those of the chimpanzee than present-day humans. Some evolutionary changes were found in known genes involved in cognitive development, skull structure, energy metabolism, skin morphology, and wound healing.
Anthropologists used the fossil record to construct tree-shaped diagrams that show how the different branches of hominins, which includes humans and human ancestors, split off from one another. These diagrams tend to proceed in a straight line, from the tree-trunk base of a common ancestor through progressively smaller branches until the species of interest is reached. The Neanderthal data suggests evolution did not proceed in a straight line. Rather, evolution appears to be a messier process, with emerging species merging back into the lines from which they diverged.
Now the view emerging from the genomic data suggests that Neanderthals – who migrated out of Africa a few hundred thousand years ago re-encountered anatomically modern humans, who began migrating out of Africa some 80,000 years ago. Humans migrating out of Africa were likely to be small pioneering groups and appear to have encountered Neanderthals living in the Fertile Crescent of the Middle East about 60,000 years ago.
"It was a very unique series of events, with a founding population of modern humans of greatly
reduced size -- tens to hundreds of individuals," Dr. Mullikin said. Geneticists can detect a population constriction or bottleneck where certain genetic markers are concentrated. That only occurs when the population is small.
"At that time," Dr. Mullikin continued, "where the population was greatly reduced, the modern
humans migrating out of Africa encountered Neanderthals and inter-breeding occurred between the two groups, leaving an additional, but subtle, genetic signature in the out-of-Africa group of modern humans."
As modern humans migrated out of the Middle East after encountering Neanderthals, and dispersed across the globe, they carried Neanderthal DNA with them. The research team concluded that 2 to 3 percent of the genomes of present-day humans living from Europe to Asia — and as far into the Pacific Ocean as Papua New Guinea — was inherited from Neanderthals. The team did not find traces of Neanderthal DNA in the two present-day humans from Africa. It is not known, however, whether a more systematic sampling of African populations will reveal the presence of Neanderthal DNA in some indigenous Africans.
"The data suggests that the genes flowed from Neanderthal to modern humans," Dr. Mullikin
said. "That had to have occurred at least once during the 20,000 to 30,000 years, in which modern humans and Neanderthal both lived on the Eurasian continent." The researchers have not yet detected any signs that DNA from modern humans can be found in the Neanderthal genome.
Previous studies, such as the International HapMap Project, which created a comprehensive
catalog of human genetic variation, examined common genetic variation in populations across the globe, and concluded that average genetic variation between a person in Asia, Europe, or Africa was essentially identical. The current study raises the possibility that Europeans and Asians, who include Neanderthal DNA, may be slightly more distinct from Africans than previously appreciated – a difference at the DNA sequence level that could not be seen with the resolution of the HapMap.
"These are preliminary data based on a very limited number of samples, so it is not clear how
widely applicable these findings are to all populations," said Vence L. Bonham, a senior advisor on Societal Implications of Genomics. "The findings do not change our basic understanding that humans originated in Africa and dispersed around the world in a migration out of that continent."
The Denisovans, a New Branch of the Human Family Tree -- Neither Modern Human Nor Neanderthal
In 2008, a 30,000-year-old finger bone was found in a cave in southern Siberia from a young girl who was neither an early modern human nor a Neanderthal, but instead belonged to a previously unknown group of human relatives who may have lived throughout much of Asia during the late Pleistocene epoch. Although the fossil evidence consists of just a bone fragment and one tooth, DNA extracted from the bone has yielded a draft genome sequence, enabling scientists to reach some startling conclusions about this extinct branch of the human family tree called "Denisovans" after the cave where the fossils were found.
The international team of researchers led by Svante Paabo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, sequenced the nuclear genome from the finger bone of the extinct hominin that was excavated by archaeologists from the Russian Academy of Sciences in Denisova Cave in southern Siberia, Russia.
Earlier in the year, the team showed that the mitochondrial DNA from the finger bone displayed an unusual sequence suggesting that it came from an undescribed ancient hominin form. Using techniques the researchers developed to sequence the Neanderthal genome, they sequenced the nuclear genome from the bone. They found that the individual was female and cames from a group of hominins that shared an ancient origin with Neanderthals, but subsequently had a distinct history. They called this group of hominins, Denisovans. Unlike Neandertals, Denisovans did not contribute genes to all present-day Eurasians. However, Denisovans share an elevated number of genetic variants with modern-day Papuan New Guinean populations, suggesting that there was interbreeding between Denisovans and the ancestors of Melanesians. In addition, a Denisovan tooth found in the same cave showed a morphology that was distinct from Neanderthals and modern humans and resembled much older hominin forms. Bence Viola, a scientist at the Max Planck Institute of evolutionary Anthropology commented "The tooth is just amazing. It allows us to connect the morphological and genetic information."
David Reich, an Associate Professor at Harvard Medical School who led the population genetic analysis, said "The fact that Denisovans were discovered in Southern Siberia but contributed genetic material to modern human populations from New Guinea suggests that Denisovans may have been widespread in Asia during the Late Pleistocene."
Svante Paabo of the Max Planck Institute of evolutionary Anthropology remarked "In combination with the Neanderthal genome sequence, the Denisovan genome suggests a complex picture of genetic interactions between our ancestors and different ancient hominin groups."
Richard Green of the University of California, Santa Cruz, played a lead role in the analysis of the genome sequence data. By comparing the Denisovan genome sequence with the genomes of Neanderthals and modern humans, the researchers determined that the Denisovans were a sister group to the Neanderthals, descended from the same ancestral population that had separated earlier from the ancestors of present-day humans. The study also found surprising evidence of Denisovan gene sequences in modern-day Melanesians, suggesting that there was interbreeding between Denisovans and the ancestors of Melanesians, just as Neanderthals appear to have interbred with the ancestors of modern-day non-Africans.
"The story now gets a bit more complicated," said Green. "Instead of the clean story we used to have of modern humans migrating out of Africa and replacing Neanderthals, we now see these very intertwined story lines with more players and more interactions than we knew of before."
The Denisovans appear to have been quite different both genetically and morphologically from Neanderthals and modern humans. The tooth found in the same cave as the finger bone shows a morphology that is distinct from Neanderthals and modern humans and resembles much older human ancestors, such as Homo habilis and Homo erectus. DNA analysis showed that the tooth and the finger bone came from different individuals in the same population.
The finger bone was found in 2008 by Russian scientists in Denisova Cave, an archaeological site in southern Siberia. Paabo, who had worked with the Russian scientists before, obtained the bone for his research on ancient DNA. In Leipzig, researchers extracted DNA from the bone and sequenced the mitochondrial genome, a smaller DNA sequence separate from the chromosomal DNA and easier to obtain from ancient samples. The results showed a surprising divergence from the mitochondrial genomes of Neanderthals and modern humans, and the team quickly began working to sequence the nuclear genome.
"It was fortuitous that this discovery came quickly on the heels of the Neanderthal genome, because we already had the team assembled and ready to do another similar analysis," Green said. "This is an incredibly well-preserved sample, so it was a joy to work with data this nice. We don't know all the reasons why, but it is almost miraculous how well-preserved the DNA is."
The relationship between Denisovans and present-day Melanesians was a completely unexpected finding, he said. The comparative analysis, which included genome sequences of individuals from New Guinea and Bougainville Island, indicates that genetic material derived from Denisovans makes up about 4 to 6 percent of the genomes of at least some Melanesian populations. The fact that Denisovans were discovered in southern Siberia but contributed genetic material to modern human populations in Southeast Asia suggests that their population may have been widespread in Asia during the late Pleistocene, said David Reich of Harvard Medical School.
It is not clear why fossil evidence had not already revealed the existence of this group of ancient human relatives. But Green noted that the finger bone was originally thought to be from an early modern human, and the tooth resembled those of other ancient human ancestors. "It could be that other samples are misclassified," he said. "But now, by analyzing DNA, we can say more definitively what they are. It's getting easier technically to do this, and it's a great new way to extract information from fossil remains."
In the light of the Neanderthal and Denisovan genomes, a new, more complex picture is emerging of the evolutionary history of modern humans and our extinct relatives. According to Green, there was probably an ancestral group that left Africa between 300,000 and 400,000 years ago and quickly diverged, with one branch becoming the Neanderthals who spread into Europe and the other branch moving east and becoming Denisovans. When modern humans left Africa about 70,000 to 80,000 years ago, they first encountered the Neanderthals, an interaction that left traces of Neanderthal DNA scattered through the genomes of all non-Africans. One group of humans later came in contact with Denisovans, leaving traces of Denisovan DNA in the genomes of humans who settled in Melanesia.
"This study fills in some of the details, but we would like to know much more about the Denisovans and their interactions with human populations," Green said. "And you have to wonder if there were other populations that remain to be discovered."
Is there a fourth player in this story?
Researchers Sequence the Genome of a 400,000 Year Old Denisovan-like Hominin in Spain
In 2013, using novel techniques to extract and study ancient DNA, researchers at the Max Planck Institute for Evolutionary Anthropology sequenced the mitochondrial genome of a 400,000-year-old hominin from Sima de los Huesos, a unique cave site in Northern Spain, and found that it was related to the mitochondrial genome of Denisovans, extinct relatives of Neanderthals in Asia. DNA this old has until recently been retrieved only from the permafrost.
Sima de los Huesos, known as the "bone pit," is a cave site in Northern Spain that has yielded the world's largest assembly of Middle Pleistocene hominin fossils, consisting of at least 28 skeletons, which have been excavated and pieced together over the course of more than two decades by a Spanish team of paleontologists led by Juan-Luis Arsuaga. The fossils are classified as Homo Heidelbergensis but also carry traits typical of Neanderthals. Until now it had not been possible to study the DNA of these unique hominins.
Matthias Meyer and his team from the Max Planck Institute developed new techniques for retrieving and sequencing highly degraded ancient DNA. They then joined forces with Juan-Luis Arsuaga and applied the new techniques to a cave bear from the Sima de los Huesos site. After this success, the researchers sampled two grams of bone powder from a hominin thigh bone from the cave. They extracted its DNA and sequenced the genome of the mitochondria, a small part of the genome that is passed down along the maternal line and occurs in many copies per cell. The researchers then compared this ancient mitochondrial DNA with Neanderthals, Denisovans, present-day humans, and apes.
From the missing mutations in the old DNA sequences the researchers calculated that the Sima hominin lived about 400,000 years ago. They also found that it shared a common ancestor with the Denisovans, an extinct archaic group from Asia related to the Neanderthals, about 700,000 years ago. "The fact that the mitochondria of the Sima de los Huesos hominin shares a common ancestor with Denisovan rather than Neanderthal mitochondria is unexpected since its skeletal remains carry Neanderthal-derived features," says Matthias Meyer. Considering their age and Neanderthal-like features, the Sima hominins were likely related to the population ancestral to both Neanderthals and Denisovans. Another possibility is that gene flow from yet another group of hominins brought the Denisovan-like mitochondria into the Sima hominins or their ancestors.
"Our results show that we can now study DNA from human ancestors that are hundreds of thousands of years old. This opens prospects to study the genes of the ancestors of Neanderthals and Denisovans. It is tremendously exciting" says Svante Paabo, director at the Max Planck Institute for Evolutionary Anthropology.
"This unexpected result points to a complex pattern of evolution in the origin of Neanderthals and modern humans. I hope that more research will help clarify the genetic relationships of the hominins from Sima de los Huesos to Neanderthals and Denisovans" says Juan-Luis Arsuaga, director of the Center for Research on Human Evolution and Behaviour. The researchers are now pursuing this goal by focusing on retrieving DNA from more individuals from this site and on retrieving also nuclear DNA sequences.
Homo Sapiens Emerged 100,000 Years Earlier Than Previously Thought
Last year, an international research team uncovered 300,000 year old fossil bones of Homo Sapiens, a find that represents the oldest reliably dated fossil evidence of our species.
The unearthing significantly pushes back the origins of our species. The find is approximately 100,000 years older than any other previously discovered Homo Sapiens fossils.
The discovery, which also included stone tools and animal bones, was made at Jebel Irhoud, Morocco, the site of multiple hominid fossil discoveries. The work also included an analysis of the tooth size and morphology of the new and previously discovered fossils -- an effort conducted by New York University Anthropology Professor Shara Bailey.
The team, led by Professor Jean-Jacques Hublin of the Max Planck Institute for Evolutionary Anthropology in Germany and Abdelouahed Ben-Ncer of the National Institute for Archaeology and Heritage in Rabat, Morocco, notes that the fossils revealed a complex evolutionary history of mankind that likely involved the entire African continent.
"We used to think that there was a cradle of mankind 200,000 years ago in East Africa, but our new data reveal that Homo Sapiens spread across the entire African continent around 300,000 years ago," observes Hublin, a palaeoanthropologist. "Long before the out-of-Africa dispersal of Homo Sapiens, there was dispersal within Africa."
Previously, the oldest securely dated Homo Sapiens fossils were discovered at two sites in Ethiopia, dating 195,000 and 160,000 years old. Consequently, many researchers believed that all humans living today descended from a population that lived in East Africa around 200,000 years ago.
"Many of these fossils have been known for a long time, but fossils discovered during the recent excavations significantly added to the collection, making it possible to undertake a comprehensive study of the cranial and dental remains," notes Bailey. "All data point to a set of derived Homo Sapiens features suggesting that some aspects of the modern human form began as early as 300,000 years ago. Moreover, it indicates that modern human origin was likely a pan-African event, rather than being concentrated in East Africa."
The team led by Hublin and Ben-Ncer uncovered fossil bones of Homo Sapiens along with stone tools and animal bones. The finds are dated to about 300,000 years ago and represent the oldest dated fossil evidence of our own species. Both genetic data of present day humans and fossil remains point to an African origin of our own species, Homo Sapiens. Previously, the oldest securely dated Homo Sapiens fossils were known from the site of Omo Kibish in Ethiopia, dated to 195,000 years ago. At Herto, also in Ethiopia, a Homo Sapiens fossil is dated to 160,000 years ago. Until now, most researchers believed that all humans living today descended from a population that lived in East Africa around 200,000 years ago. "We used to think that there was a cradle of mankind 200,000 years ago in East Africa, but our new data reveal that Homo Sapiens spread across the entire African continent around 300,000 years ago." says palaeoanthropologist Jean-Jacques Hublin.
The Moroccan site of Jebel Irhoud has been well known since the 1960s for its human fossils and for its Middle Stone Age artifacts. However, the interpretation of the Irhoud hominins has long been complicated by persistent uncertainties surrounding their geological age. The new excavation project, which began in 2004, resulted in the discovery of new Homo Sapiens fossils in-situ, increasing their number from 6 to 22. These finds confirm the importance of Jebel Irhoud as the oldest and richest African Middle Stone Age hominin site documenting an early stage of our species. The fossil remains from Jebel Irhoud comprise skulls, teeth, and long bones of at least five individuals. To provide a precise chronology for these finds, researchers used the thermoluminescence dating method on heated flints found in the same deposits. These flints yielded an age of approximately 300,000 years and, therefore, push back the origins of our species by 100,000 years.
"Well dated sites of this age are exceptionally rare in Africa, but we were fortunate that so many of the Jebel Irhoud flint artifacts had been heated in the past," says geochronology expert Daniel Richter of the Max Planck Institute. Now with Freiberg Instruments GmbH, Richter explains "This allowed us to apply thermoluminescence dating methods on the flint artifacts and establish a consistent chronology for the new hominin fossils and the layers above them."
In addition, the team was able to recalculate a direct age of the Jebel Irhoud mandible found in the 1960s. This mandible had been previously dated to 160,000 years ago by a special electron spin resonance dating method. Using new measures of the radioactivity of the Jebel Irhoud sediments and as a result of methodological improvements in the method, the newly calculated age of the fossil is in agreement with the thermoluminescence ages and much older than previously thought. "We employed state of the art dating methods and adopted the most conservative approaches to accurately determine the age of Irhoud," adds Richter.
The crania of modern humans living today are characterized by a combination of features that distinguish us from our fossil relatives and ancestors -- a small and slender face and a globular braincase. The fossils from Jebel Irhoud display a modern-looking face and teeth and a large but more archaic-looking braincase.
Hublin and his team used state-of-the-art micro computed tomographic scans and statistical shape analysis based on hundreds of 3D measurements to show that the facial shape of the Jebel Irhoud fossils is almost indistinguishable from that of modern humans living today. In contrast to their modern facial morphology, however, the Jebel Irhoud crania retain a rather elongated archaic shape of the braincase.
"The inner shape of the braincase reflects the shape of the brain," explains palaeoanthropologist Philipp Gunz from the Max Planck Institute for Evolutionary Anthropology. "Our findings suggest that modern human facial morphology was established early on in the history of our species, and that brain shape, and possibly brain function, evolved within the Homo Sapiens lineage," says Gunz.
Recently, comparisons of ancient DNA extracted from Neanderthals and Denisovans to the DNA of present day humans revealed differences in genes affecting the brain and nervous system. Evolutionary shape changes of the braincase are therefore likely related to a series of genetic changes affecting brain connectivity, organization, and development that distinguish Homo Sapiens from our extinct ancestors and relatives.
The morphology and age of the fossils from Jebel Irhoud also corroborate the interpretation of an enigmatic partial cranium from Florisbad, South Africa, as an early representative of Homo Sapiens. The earliest Homo Sapiens fossils are found across the entire African continent: Jebel Irhoud, Morocco (300,000 years), Florisbad, South Africa (260,000 years), and Omo Kibish, Ethiopia (195,000 years). This indicates a complex evolutionary history of our species, possibly involving the whole African continent.
"North Africa has long been neglected in the debates surrounding the origin of our species. The spectacular discoveries from Jebel Irhoud demonstrate the tight connections of the Maghreb with the rest of the African continent at the time of Homo Sapiens emergence," says Abdelouahed Ben-Ncer.
The fossils were found in deposits containing animal bones showing evidence of having been hunted, with the most frequent species being gazelle. The stone tools associated with these fossils belong to the Middle Stone Age. The Jebel Irhoud artifacts show the use of Levallois prepared core techniques and pointed forms are the most common. Most stone tools were made from high quality flint imported into the site. Handaxes, a tool commonly found in older sites, are not present at Jebel Irhoud. Middle Stone Age artifact assemblages such as the one recovered from Jebel Irhoud are found across Africa at this time and likely speak to an adaptation that allowed Homo Sapiens to disperse across the continent.
"The stone artifacts from Jebel Irhoud look very similar to ones from deposits of similar age in East Africa and in Southern Africa" says Max Planck Institute archaeologist Shannon McPherron. "It is likely that the technological innovations of the Middle Stone Age in Africa are linked to the emergence of Homo Sapiens."
The new findings from Jebel Irhoud elucidate the evolution of Homo Sapiens and show that our species evolved much earlier than previously thought. The dispersal of Homo Sapiens across all of Africa around 300,000 years ago is the result of changes in both biology and behavior.
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