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coldrum
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|  New Message Posted!2013-05-16 20:14
What Modern Humans Can Learn From The Neanderthals' Extinction
It's a fact of the archaeological record: Modern humans survived and Neanderthals did not. Why? And what does it teach us about our own survival?
Neanderthals were humans who went extinct between 20,000 and 30,000 years ago. Though there is some debate about who these people were, there is no question that there are none left. All that remains of the hundreds of Neanderthal groups that roved across Europe and Central Asia are a handful of ambiguous funeral sites, bones, tools, and pieces of art—along with some DNA that modern humans inherited from them. How can we avoid meeting the Neanderthals’ fate? That depends on what you think wiped out these early humans in the millennia after they met H. sapiens.
Scatter, Adapt, and Remember:
Scatter, Adapt, and Remember: How Humans Will Survive a Mass Extinction by Annalee Newitz is available on Amazon. Doubleday
By 40,000 years ago, humans had spread in waves across most of the world, from Africa to Europe, Asia, and even Australia. But these humans were not all perfectly alike. When some groups of H. sapiens poured out of Africa, they walked north, then west. In this thickly forested land, they came face-to-face with other humans, stockier and lighter skinned than themselves, who had been living for thousands of years in the cold wilds of Europe, Russia, and Central Asia. Today we call these humans Neanderthals, a name derived from the Neander Valley caves in Germany where the first Neanderthal skull was identified in the nineteenth century.
Neanderthals were not one unified group. They had spread far enough across Europe, Asia, and the Middle East that they formed regional groups, something like modern human tribes or races, who probably looked fairly different from each other. Neanderthals used tools and fire, just as H. sapiens did, and the different Neanderthal groups probably had a variety of languages and cultural traditions. But in many ways they were dramatically unlike H. sapiens, leading isolated lives in small bands of 10 to 15 people, with few resources. They had several tools, including spears for hunting and sharpened flints for scraping hides, cutting meat, and cracking bones. Unlike H. sapiens, who ate a wide range of vegetables and meat, Neanderthals were mostly meat-eaters who endured often horrifically difficult seasons with very little food. Still, there is evidence that they cared for each other through hardship: fossils retrieved from a cave in Iraq include the skeleton of a Neanderthal who had been terribly injured, with a smashed eye socket and severed arm, whose bones had nevertheless healed over time. Like humans today, these hominins nursed each other back to health after life-threatening injuries.
Roughly 10,000 years after their first meeting with H. sapiens, all the Neanderthal groups were extinct and H. sapiens was the dominant hominin on Earth. What happened during those millennia when H. sapiens lived alongside creatures who must have looked to them like humanoid aliens?
A few decades ago, most scientists would have answered that it was a nightmare. Stanford’s Richard Klein, who spent years in France comparing the tools of Neanderthals and early H. sapiens, lowered his voice a register when I recently asked him to describe the meeting between these hominin groups. “You don’t like to think about a holocaust, but it’s quite possible,” he said. He referred to the long-standing belief among many anthropologists that H. sapiens exterminated Neanderthals with superior weapons and intellect. For a long time, there seemed to be no other explanation for the rapid disappearance of Neanderthals after H. sapiens arrived in their territories.
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Science, annalee newitz, book excerpt, neanderthals, scatter adapt and remember
Today, however, there is a growing body of evidence from the field of population genetics that tells a very different story about what happened when the two groups of early humans lived together, sharing the same caves and hearths. Anthropologists like Milford Wolpoff, of the University of Michigan, and John Hawks have suggested that the two groups formed a new, hybrid human culture. Instead of exterminating Neanderthals, their theory goes, H. sapiens had children with them until Neanderthals’ genetic uniqueness slowly dissolved into H. sapiens over the generations. This idea is supported by compelling evidence that modern humans carry Neanderthal genes in our DNA.
Regardless of whether H. sapiens murdered or married the Neanderthals they met in the frozen forests of Europe and Russia, the fact remains that our barrel-chested cousins no longer walk among us. They are a group of humans who went extinct. The story of how that happened is as much about survival as it is about destruction.
The Neanderthal Way of Life
We have only fragmentary evidence of what Neanderthal life was like before the arrival of H. sapiens. Though they would have looked different from H. sapiens, they were not another species. Some anthropologists call Neanderthals a “subspecies” to indicate their evolutionary divergence from us, but there is strong evidence that Neanderthals could and did interbreed with H. sapiens. Contrary to popular belief, Neanderthals probably weren’t swarthy; it’s likely that these early humans were pale-skinned, possibly with red hair. We know that they used their spears to hunt mammoths and other big game. Many Neanderthal skeletons are distorted by broken bones that healed, often crookedly; this suggests that they killed game in close combat with it, sustaining many injuries in the process. They struggled with dramatic climate changes too. The European and Asian climates swung between little ice ages and warmer periods during the height of Neanderthal life, and these temperature changes would have constantly pushed the Neanderthals out of familiar hunting grounds. Many of them took shelter from the weather in roomy caves overlooking forested valleys or coastal cliffs.
Though their range extended from Western Europe to Central Asia, the Neanderthal population was probably quite small—a generous estimate would put it at 100,000 individuals total at its apex, and many scientists believe it could have been under 10,000. By examining the growth of enamel on Neanderthal teeth, anthropologists have determined that many suffered periods of extreme hunger while they were young. This problem may have been exacerbated by their meat-heavy diets. When mammoth hunting didn’t go well, or a particularly cold season left their favored game skinny or sick, the Neanderthals would have gone through months of malnutrition. Though Neanderthals buried their dead, made tools, and (at least in one case) built houses out of mammoth bones, we have no traditional evidence that they had language or culture as we know them. Usually such evidence comes in the form of art or symbolic items left behind. Neanderthals did make art and complex tools after meeting H. sapiens, but we have yet to find any art that is unambiguously Neanderthal in origin.
Still, there are intriguing hints. A 60,000-year-old Neanderthal grave recently discovered in Spain suggests that Neanderthals may have had symbolic communication before H. sapiens arrived. Researchers discovered the remains of three Neanderthals who appeared to have been gently laid in identical positions, their arms raised over their heads, then covered in rocks. The severed paws of a panther were found with the bodies, heightening the impression that the discovery represented a funeral ritual complete with “burial goods,” or symbolic items placed in the graves. Erik Trinkhaus, an anthropologist at Washington University in St. Louis, says this site shows that Neanderthals might have had symbolic intelligence like modern humans.
Gravesites like these have led many scientists, including Trinkhaus, to believe that Neanderthals talked or even sang. But we haven’t found enough archaeological evidence to sway the entire scientific community one way or the other.
By contrast, the H. sapiens groups who lived at the time of first contact with Neanderthals left behind ample evidence of symbolic thought. Bone needles attest to the fact that H. sapiens sewed clothing, and pierced shells suggest jewelry. There are even traces of red-ochre mixtures found in many H. sapiens campsites, which could have been used for anything from paint or dye to makeup. Added together, these bits of evidence suggest that H. sapiens groups weren’t just using tools for survival; they were using them for adornment. And culture as we know it probably started with those simple adornments.
Looked at from the perspective of Neanderthals, then, there might have been a vast gulf between themselves and the newly arrived H. sapiens. The newcomers not only looked different—they were taller, slimmer, and had smaller skulls—but they probably chattered in an incomprehensibly complex language and wore bizarre garments. Would Neanderthals have tried to communicate with these people, or invited them to a dinner of mammoth meat?
There was a lot more than hanky-panky going on.For anthropologists like Klein, who spoke about a Neanderthal holocaust, the answer is an emphatic no. He’s part of a school of anthropological thought that holds that H. sapiens would have met the Neanderthals with nothing but hate, disgust, and indifference to their plight. After those Neanderthals watched H. sapiens arrive, the next chapter in their lives would have been marked by bloodshed and starvation as H. sapiens murdered and outhunted them with their superior weaponry. Neanderthals were so poor, and had such a small population, that their extinction was inevitable.
This story might sound familiar to anyone versed in the colonial history of the Americas. It’s as if H. sapiens is playing the role of Europeans arriving in their ships, and Neanderthals are playing that of the soon-to-be-exterminated natives. But Klein sees a sharp contrast between Neanderthals and the natives that Europeans met in America. When H. sapiens arrived, he asserted, “there was no cultural exchange” because the Neanderthals had no culture. Imagine what might have happened if the Spanish had arrived in the Americas, but the locals had no wealth, science, sprawling cities, nor vast farms. The Neanderthals had nothing to trade with H. sapiens, and so the newcomers saw them as animals.
Neanderthals may have had fleeting sexual relationships with H. sapiens here and there, admitted Klein, but “modern human males will mate with anything.” Tattersall agreed. “Maybe there was some Pleistocene hanky-panky,” he joked. But it wasn’t a sign of cultural bonding. For anthropologists like Klein and Tattersall, any noncombative relationships forged between the two human groups were more like fraternization than fraternity.
But there is a counter-narrative told by a new generation of anthropologists. Bolstered by genetic discoveries that have revealed traces of Neanderthal genes in the modern human genome, these scientists argue that there was a lot more than hanky-panky going on. Indeed, there is evidence that the arrival of H. sapiens may have dramatically transformed the impoverished Neanderthal culture. Some Neanderthal cave sites hold a mixture of traditional Neanderthal tools and H. sapiens tools. It’s hard to say whether these remains demonstrate an evolving hybrid culture, or if H. sapiens simply took over Neanderthal caves and began leaving their garbage in the same pits that the Neanderthals once used. Still, many caves that housed Neanderthals shortly before the group went extinct are full of ornaments, tools, and even paints. Were they emulating their H. sapiens counterparts? Had they become part of an early human melting pot, engaging in the very cultural exchange that Klein and Tattersall have dismissed?
Extermination and Assimilation
The complicated debate over what happened to Neanderthals can be boiled down to two dominant theories: Either H. sapiens destroyed the other humans, or joined up with them.
The “African replacement” theory, sometimes called the recent African origins theory, holds that H. sapiens charged out of Africa and crushed H. neanderthalensis underfoot. This fits with Klein’s account of a Neanderthal holocaust. Basically, H. sapiens groups replaced their distant cousins, probably by making war on them and taking over their territories. This theory is simple, and has the virtue of matching the archaeological evidence we find in caves where Neanderthal remains are below those of H. sapiens, as if modern humans pushed their Neanderthal counterparts out into the cold to die.
In the late 1980s, a University of Hawaii biochemist named Rebecca Cann and her colleagues found a way to support the African replacement theory with genetic evidence, too. Cann’s team published the results of an exhaustive study of mitochondrial DNA, small bits of genetic material that pass unchanged from mothers to children. They discovered that all humans on Earth could trace their genetic ancestry back to a single H. sapiens woman from Africa, nicknamed Mitochondrial Eve. If all of us can trace our roots back to one African woman, then how could we be the products of crossbreeding? We must have rolled triumphantly over the Neanderthals, spreading Mitochondrial Eve’s DNA everywhere we went. But mitochondrial DNA offers us only a small part of the genetic picture. When scientists sequenced the full genomes of Neanderthals, they discovered several DNA sequences shared by modern humans and their Neanderthal cousins.
Besides, how likely is it that a group of H. sapiens nomads would attack a community of Neanderthals? These were explorers, after all, probably carrying their lives on their backs. Neanderthals may not have had a lot of tools, but they did have deadly spears they used to bring down mammoths. They had fire. Even with H. sapiens’ greater numbers, would these interlopers have had the resources to mount a civilization-erasing attack? Rather than starting a resource-intensive war against their neighbors, many H. sapiens could have opted to trade with the odd-looking locals, and eventually move in next to them. Over time, through trade (and, yes, the occasional battle) the two groups would have shared so much culturally and genetically that it would become impossible to tell them apart.
This is precisely the kind of thinking that animates what’s called the multiregional theory of human development. Popularized by Wolpoff and his colleague John Hawks, this theory fits with the same archaeological evidence that supports the African replacement theory—it’s just a very different interpretation.
Wolpoff’s idea hinges on the notion that the ancestors of Neanderthals and H. sapiens didn’t leave Africa as distinct groups, never to see each other again until the fateful meeting that Klein described with such horror. Instead, Wolpoff suggests, humans leaving Africa 1.8 million years ago forged a pathway that many other archaic humans walked—in both directions. Instead of embarking on several distinct migrations off the continent, humans expanded their territories little by little, essentially moving next door to their old communities rather than trekking thousands of kilometers to new homes. Indeed, the very notion of an “out of Africa” migration is based on an artificial political boundary between Africa and Asia, which would have been meaningless to our ancestors. They expanded to fill the tropical forests they loved, which happened to stretch across Africa and Asia during many periods in human evolution. Early humans would have been drifting back and forth between Africa, Asia, and Europe for hundreds of thousands of years. It was all just forest to Neanderthals and H. sapiens.
If scientists like Wolpoff are right—and Hawks has presented compelling genetic evidence to back them up—then H. sapiens probably didn’t march out of Africa all at once and crush all the other humans. Instead, they evolved all over the world through an extended kinship network that may have included Neanderthals as well as other early humans like Denisovans and H. erectus.
It’s important to understand that the multiregional theory does not suggest that two or three separate human lineages evolved in parallel, leading to present-day racial groups. That’s a common misinterpretation. Multiregionalism describes a human migration scenario similar to those we’re familiar with among humans today, where people cross back and forth between regions all the time. For multiregionalists, there were never two distinct waves of immigration, with one leading to Neanderthals, and the other packed with H. sapiens hundreds of thousands of years later. Instead, the migration (and evolution) of H. sapiens started 1.8 million years ago and never stopped.
Many anthropologists believe that the truth lies somewhere in between African replacement and multiregionalism. Perhaps there were a few distinct waves of migration, such anthropologists will concede, but H. sapiens didn’t “replace” the Neanderthals. Instead, H. sapiens bands probably assimilated their unusual cousins through the early human version of intermarriage.
Perhaps, when Neanderthals stood in the smooth stone entries to their caves and watched H. sapiens first entering their wooded valleys, they saw opportunity rather than a confusing threat. In this version of events, our ancient human siblings may have had few resources and lived a hardscrabble life, but they were H. sapiens’ mental equals. They exchanged ideas with the newcomers, developed ways of communicating, and raised families together. Their hybrid children deeply affected the future of our species, with a few of the most successful Neanderthal genes drifting outward into some of the H. sapiens population. Neanderthals went extinct, but their hybrid children survived by joining us.
Whether you believe that humans exterminated or assimilated Neanderthals depends a lot on what you believe about your own species. Klein doesn’t think Neanderthals were inferior humans doomed to die—he simply believes that early H. sapiens would have been more likely to kill and rape their way across Europe in a Neanderthal holocaust, rather than making alliances with the locals. As his comment about the sexual predilections of modern men makes clear, Klein is basing his theory on what he’s observed of H. sapiens in the contemporary world. Tattersall amplified Klein’s comments by saying that he thinks humans 40,000 years ago probably treated Neanderthals the way we treat each other today. “Today, Homo sapiens is the biggest threat to its own survival. And [the Neanderthal extinction] fits that picture,” he said. Ultimately, Tattersall believes that we wiped out the Neanderthals just the way we’re wiping ourselves out today.
Hawks, on the other hand, described a more complicated relationship between H. sapiens and Neanderthals. He believes that Neanderthals had the capacity to develop culture, but simply didn’t have the resources.
Modern humans carry Neanderthal genes in our DNA.“They made it in a world where very few of us would make it,” he said, referring to the incredible cold and food scarcity in the regions Neanderthals called home. Anthropologists, according to Hawks, often ask the wrong questions of our extinct siblings: “Why didn’t you invent a bow and arrow? Why didn’t you build houses? Why didn’t you do it like we would?” He thinks the answer isn’t that the Neanderthals couldn’t but that they didn’t have the same ability to share ideas between groups the way H. sapiens did. Their bands were so spread out and remote that they didn’t have a chance to share information and adapt their tools to life in new environments. “They were different, but that doesn’t mean there was a gulf between us,” Hawks concluded. “They did things working with constraints that people today have trouble understanding.” Put another way, Neanderthals spent all day in often fatal battles to get enough food for their kids to eat. As a result, they didn’t have the energy to invent bows and arrows in the evening. Despite these limitations, they formed their small communities, hunted collectively, cared for each other, and honored their dead.
When H. sapiens arrived, Neanderthals finally had access to the kind of symbolic communication and technological adaptations they’d never been able to develop before. Ample archaeological evidence shows that they quickly learned the skills H. sapiens had brought with them, and started using them to adapt to a world they shared with many other groups who exchanged ideas on a regular basis. Instead of being driven into extinction, they enjoyed the wealth of H. sapiens’ culture and underwent a cultural explosion of their own. To put it another way, H. sapiens assimilated the Neanderthals. This process was no doubt partly coercive, the way assimilation so often is today.
More evidence for Hawks’s claims comes from Neanderthal DNA. Samples of their genetic material can reveal just what happened after all that Pleistocene hanky-panky. A group of geneticists at the Max Planck Institute, led by Svante Pääbo, sequenced the genomes of a few Neanderthals who had died less than 38,000 years ago. After isolating a few genetic sequences that appear unique to Neanderthals, they found evidence that a subset of these sequences entered the H. sapiens genome after the first contact between the two peoples. Though this evidence does not prove definitively that genes flowed from Neanderthals into modern humans, it’s a strong argument for an assimilationist scenario rather than extermination.
Our lineage is a patchwork quilt of many peoples and cultures who intermingled as they spread across the globe.A big question for anthropologists has been whether H. sapiens comes from a “pure” lineage that springs from a single line of hominins like Mitochondrial Eve. The more the genetic evidence piles up, however, the more likely it seems that our lineage is a patchwork quilt of many peoples and cultures who intermingled as they spread across the globe. Present-day humans are the offspring of people who survived grueling immigrations, harsh climates, and Earth-shattering disasters.
Most anthropologists are comfortable admitting that we just don’t know what happened when early humans left Africa, and are used to revising their theories when new evidence presents itself. Klein’s influential textbook The Human Career is full of caveats about how many of these theories are under constant debate and revision. In 2011, for example, the anthropologist Simon Armitage published a paper suggesting that H. sapiens emerged from Africa as early as 200,000 years ago, settling in the Middle East. This flies in the face of previous theories, which hold that H. sapiens didn’t leave Africa until about 70,000 years ago. The story of how our ancestors emerged from their birthplaces in Africa turns out to be as complicated as a soap opera—and it likely includes just as much sex and death, too.
Who Survived to Tell the Tale?
Whether humans destroyed Neanderthals or merged with them, we’re left with a basic fact of anthropological history, which is that modern humans survived and Neanderthals did not. It’s possible that members of H. sapiens were better survivors than their hominin siblings because Neanderthals didn’t exchange symbolic information; they were too sparse, spread out, and impoverished to achieve a cultural critical mass the way their African counterparts did. But it seems that Neanderthals were still swept up into H. sapiens’ way of life in the end. Our Neanderthal siblings survive in modern human DNA because they formed intimate bonds with their new human neighbors.
Svante Pääbo, who led the Neanderthal DNA sequencing project, recently announced a new discovery that also sheds light on why H. sapiens might have been a better survivor than H. neanderthalensis. After analyzing a newly sequenced genome from a Denisovan, a hominin more closely related to Neanderthals than H. sapiens are, Pääbo’s team concluded that there were a few distinct regions of DNA that H. sapiens did not share with either Neanderthals or Denisovans. Several of those regions contain genes connected to the neurological connections that humans can form in their brains. In other words, it’s possible that H. sapiens’ greater capacity for symbolic thought is connected to unique strands of DNA that the Neanderthals didn’t have. “It makes a lot of sense to speculate that what had happened is about connectivity in the brain, because... Neanderthals had just as large brains as modern humans had,” Pääbo said at a press conference in 2012 after announcing his discovery. “Relative to body size, they had even a bit larger brains [than H. sapiens]. Yet there is something special that happens with modern humans. It’s sort of this extremely rapid technological cultural development and large societal systems, and so on.” In other words, H. sapiens’ brains were wired slightly differently than their fellow hominins. And once Neanderthals merged with H. sapiens’ communities, bearing children with the new arrivals, their mixed offspring may have had brains that were wired differently, too. Looked at in this light, it’s as if H. sapiens assimilated Neanderthals both biologically and culturally into an idea-sharing tradition that facilitated rapid adaptation even to extremely harsh conditions.
Early humans evolved brains that helped us spread ideas to our compatriots even as we scattered to live among new families and communities. It’s possible that this connectedness—both neurological and social—is what allowed groups of H. sapiens to assimilate their siblings, the Neanderthals. Still, our storytelling abilities are also what allow us to remember these distant, strange ancestors today.
Humans’ greatest strength 30,000 years ago may have been an uncanny ability to assimilate other cultures. But in more recent human history, this kind of connectedness almost did us in. Once human culture scaled up to incorporate unprecedentedly enormous populations, our appetite for assimilation spread plagues throughout the modern world, almost destroying humanity many times over. And it spawned deadly famines, too. Humanity’s old community-building habits can become pathological on a mass scale. Thousands of years after the merging of Neanderthals and H. sapiens, the practices that helped us survive in pre–ice age Europe became, in some contexts, liabilities. They wiped out whole civilizations and made it necessary for us to change the structures of human community forever.
http://www.popsci.com/science/article/2013-05/how-avoid-meeting-neanderthals-fate
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coldrum
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| New Message Posted!2013-05-15 19:56
Brain Structure, Not the Frontal Lobe, Responsible for Advanced Human Intelligence, Say Evolutionist Researchers
Using phylogenetic or 'evolutionary family tree' techniques, Professor Robert Barton from the Department of Anthropology at Durham University analyzed data developed from previous animal and human studies to examine the speed at which evolutionary biological change in the brain occurred. His results could be a game-changer when it comes to understanding how the brains of our distant ancient ancestors changed during the course of human evolution. He and his research colleagues at Durham and Reading universities have concluded that, contrary to popular scholarly conception, the frontal lobes of the brain did not evolve comparatively faster than their primate cousins after the human lineage split from the chimpanzee lineage about 5-7 million years ago. It was actually just as much, if not more, about the evolution of the overall brain structure.
"It has been thought that frontal lobe expansion was particularly crucial to the development of modern human behaviour, thought and language, and that it is our bulging frontal lobes that truly make us human", says Barton. "We show that this is untrue: human frontal lobes are exactly the size expected for a non-human brain scaled up to human size. This means that areas traditionally considered to be more primitive were just as important during our evolution. These other areas should now get more attention."
Barton and colleagues maintain that many of the advanced cognitive abilities that distinguish us from other animals are made possible by more extensive brain networks linking many different areas of the brain. They point to the structure of these extended networks more than the comparative size of any particular brain region as the key.
The frontal lobes are an area located at the front of each cerebral hemisphere in all mammals, and have been traditionally thought to be critical for intelligence, or cognitive thinking. While this may be at least in part true, Barton and colleagues are now suggesting that scientists begin to focus on the evolution of other parts of the brain and how they are interconnected and contribute to the total functionality that defines human intelligence.
A detailed report of the study is published in the Proceedings of the National Academy of Sciences (PNAS).
http://popular-archaeology.com/issue/march-2013/article/brain-structure-not-the-frontal-lobe-responsible-for-advanced-human-intelligence-say-evolutionist-researchers
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coldrum
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| New Message Posted!2013-05-15 19:49
Prehistoric ear bones could lead to evolutionary answers
The tiniest bones in the human body – the bones of the middle ear – could provide huge clues about our evolution and the development of modern-day humans, according to a study by a team of researchers that include a Texas A&M University anthropologist.
Darryl de Ruiter, a professor in the Department of Anthropology at Texas A&M, and colleagues from Binghamton University (the State University of New York) and researchers from Spain and Italy have published their work in the current issue of PNAS (Proceedings of the National Academy of Science).
The team examined the skull of a hominin believed to be about 1.9 million years old and found in a cave called Swartkrans, in South Africa. Of particular interest to the team were bones found in the middle ear, especially one called the malleus. It and the other ear bones – the incus and the stapes – together show a mixture of ape-like and human-like features, and represent the first time all three bones have been found together in one skull.
The malleus appears to be very human-like, the findings show, while the incus and stapes resemble those of a more chimpanzee-like, or ape-like creature. Since both modern humans and our early ancestors share this human-like malleus, the changes in this bone must have occurred very early in our evolutionary history.
"The discovery is important for two reasons," de Ruiter explains.
"First, ear ossicles are fully formed and adult-sized at birth, and they do not undergo any type of anatomical change in an individual lifetime. Thus, they are a very close representation of genetic expression. Second, these bones show that their hearing ability was different from that of humans – not necessarily better or worse, but certainly different.
"They are among the rarest of fossils that can be recovered," de Ruiter adds.
"Bipedalism (walking on two feet) and a reduction in the size of the canine teeth have long been held to be 'hallmarks of humanity' since they seem to be present in the earliest human fossils recovered to date. Our study suggests that the list may need to be updated to include changes in the malleus as well."
de Ruiter recently authored a series of papers in Science magazine that demonstrate the intermediate nature of the closely related species, Australopithecus sediba, and provide strong support that this species lies rather close to the ancestry of Homo sapiens. The current study could yield additional new clues to human development and answer key questions of the evolution of the human lineage.
Read more at: http://phys.org/news/2013-05-prehistoric-ear-bones-evolutionary.html#jCp
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coldrum
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| New Message Posted!2013-05-14 19:42
Scientists Find Groundbreaking New Surprises in Examination of Early Human Ancestor
It dominated science headlines when the news was first released. The discovery of the remains of a new species of ancient hominin (human ancestor) revealed a candidate that sported a mosaic of features both ape-like and human -- an unprecedented 2-million-year-old hybrid called Australopithecus sediba (Au. sediba). First stumbled upon in 2008 by Professor Lee Berger of the University of the Witwatersrand and his then 9-year-old son Matthew at the fossil bearing site of Malapa in South Africa, the finds, consisting of remarkably complete skeletal remains as well as other well-preserved fauna and flora, instantly became the subject of perhaps the most intense and thoroughly studied hominin fossils ever documented.
The team, led by Berger and composed of South African and international scientists from the Evolutionary Studies Institute (ESI) at the University of the Witwatersrand (Wits) and 16 other global institutions (totalling more than 100 researchers from around the world), recently examined the anatomy of Au. sediba based on its skeletons catalogued as "MH1" (a juvenile skeleton) and "MH2" (an adult female skeleton), as well as an adult isolated tibia catalogued as "MH4". The scientists have now completed what amounts to the second 2-year installment of a series of studies begun approximately four years ago, and the efforts of their research have resulted in additional new surprises. Dispersed among six separate studies, these latest examinations have determined in essence how the hominin walked, chewed and moved:
(1) DENTAL MORPHOLOHY AND THE PHYLOGENETIC "PLACE" OF AUSTRALOPETHICUS SEDIBA
The first study, led by Professor Joel Irish from the Research Centre for Evolutionary Anthropology and Palaeoecology at Liverpool John Moores University in the United Kingdom, examined dental traits in the subject fossils.
In this study, Irish, Debbie Guatelli-Steinberg of the Ohio State University and their colleagues examined the teeth from sediba and compared them to eight other African hominin species, which include modern humans from Africa, and extinct species of Homo, Australopithecus, and Paranthropus. In all, the researchers examined more than 340 fossils and 4,571 recent specimens. They also examined teeth from 44 gorillas for comparison.
Based on the examination, Irish and his colleagues suggest that the species is distinct from east African australopiths (a more ape-like hominin genus found in east Africa, such as at Olduvai Gorge and the Afar region of Ethiopia), but is close to Au. africanus (an ape-like hominin genus found in southern Africa), thus forming a southern African australopith "clade" (a group consisting of an ancestor and all its descendants).
The latter, in turn, shares a number of derived states or physical characteristics with a clade comprising four fossil samples of the genus Homo (the genus that includes modern humans and species closely related to them ). This surprising result has significant implications for our present understanding of hominin phylogeny (the evolution of the species), and alludes to the possibility that Au. sediba, and perhaps Au. africanus are not descendant from the Au. afarensis lineage, represented most prominently by the famous "Lucy" skeleton discovered by Donald Johanson in Ethiopia in 1974, as has been widely hypothesized.
"Our research on teeth can't definitively settle if either sediba or africanus is more closely related to humans than the other species," Guatelli-Steinberg said. "But our findings do suggest that both are closely related to each other and are more closely related to humans than afarensis."
Irish noted that even though the results of this study were surprising and were bound to be viewed as controversial given the long held hypotheses relating to the origins of the genus Homo (the genus more directly ancestral to humans), he would have come to the same conclusion.
"The extreme age and rarity of these fossils naturally draws enhanced interest in and scrutiny of any new findings", he says. "Based on the evidence, I would have come up with the same conclusions whether the samples were three million or 30 years old."
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Malapa Hominin 1 (MH1) left, Lucy (AL 288-1 (Centre), and Malapa Hominin 2 (MH2) right. Image compiled by Peter Schmid courtesy of Lee R. Berger, University of the Witwatersrand.
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(2) MANDIBULAR REMAINS
Professor Darryl de Ruiter of Texas A&M and the Evolutionary Studies Institute at the University of the Witwatersrand, and his colleagues, examined new mandibular (lower jaw) material from the MH2 individual.
The study concludes that the mandibular remains share similarities with other australopiths, but can be differentiated from the southern African ape-man Au. africanus in both size and shape, as well as in their growth trajectory.
"These results add further support to the claim that Au. sediba is taxonomically distinct from the temporally – and geographically – close species Au. africanus. Where the Au. sediba mandibles differ from those of Au. africanus, they appear most similar to representatives of early Homo," says De Ruiter.
(3) THE UPPER LIMB
Professor Steven Churchill of Duke University and the Evolutionary Studies Institute at University of the Witwatersrand and his examined new, remarkably well preserved upper limb elements of Au. sediba.
They announce the first complete (or nearly complete) and undistorted humerus, radius, ulna, scapula, clavicle and manubrium (a frontal chest bone) yet described from the early hominin record, all associated with one individual.
The researchers noted that with the exception of the hand skeleton (which exhibits a suite of derived features that may signal enhanced manipulative capabilities relative to earlier australopiths), the upper limbs of the Malapa hominins are largely primitive in their morphology (physical characteristics). Au. sediba thus shares with other australopiths an upper limb that was well-suited for arboreal or other forms of climbing and possibly suspension, though perhaps more so than has been previously suggested for any other member of the australopith genus.
Churchill adds that "it is possible that the climbing features in the skeleton of Australopithecus sediba and other australopiths are functionally unimportant primitive traits retained from a more arboreal ancestor. Even so, it is curious that these features persist unchanged for several million years, only to abruptly disappear with the emergence of the genus Homo."
(4) MORPHOLOGY OF THE THORAX
Dr. Peter Schmid and colleagues at the Evolutionary Studies Institute at the University of the Witwatersrand and the University of Zurich studied the remains of the rib cage of Au. sediba.
Their findings reveal a narrow upper thorax, much like that of the large-bodied apes, and unlike the broad, cylindrical chest characteristic of humans. In conjunction with the largely complete remains of the shoulder girdle, Schmid notes that "the morphological picture that emerges is one of a conical thorax with a high shoulder joint that produces in Au. sediba an ape-like "shrugged" shoulder appearance, and thus a configuration that is perhaps uniquely australopith, and that would not have been conducive to human-like swinging of the arms during bipedal striding and running".
The research however shows that the less well-preserved elements of the lower rib cage suggest some degree of human-like narrowing to the lower thorax, a surprising feature that is not like that of Homo erectus or H. sapiens (modern humans). Homo erectus is an extinct species of hominin that lived from around 1.8 million years ago to around 300,000 years ago. The species is thought to have originated in Africa and spread as far as England, Georgia, India, China and Java.
(5) THE VERTEBRAL COLUMN
Dr Scott Williams of the Center for the Study of Human Origins at New York University and colleagues examined the vertebral column of Au. sediba, including the cervical, thoracic, lumbar, and sacral regions of the vertebral column.
The researchers describe a remarkably articulated lumbar vertebral region that shows a human-like curvature of the lower back. Williams notes that "the adult female is the first early hominin skeleton that preserves an intact terminal thoracic region and this provides critical information on the transition in inter-vertebral joints, and, by inference, mobility of the lower back".
The study also demonstrates that Au. sediba had the same number of lumbar vertebrae as modern humans, but possessed a functionally longer and more flexible lower back. In addition, morphological indicators of strong lumbar curvature suggest that Au. sediba was more similar to the Nariokotome Homo erectus skeleton than to the australopiths.
(6) THE LOWER LIMB AND THE MECHANICS OF WALKING
Dr. Jeremy DeSilva and colleagues at Boston University and the Evolutionary Studies Institute at the University of the Witwatersrand examined the lower limb anatomy of Au. sediba. i
"The female Australopithecus sediba preserves a heel, ankle, knee, hip and lower back- all of the ingredients necessary to reconstruct how she walked with remarkable precision. Even the famous Lucy skeleton only preserves two of these five (ankle and hip)", says DeSilva.
In isolation, the anatomies of the heel, mid-foot, knee, hip, and back are unique and curious, but in combination, they are internally consistent for a biped walking with a hyper-pronating gait (relative to the modern human gait, feet that pronates or rotates too much, for too long at the wrong time during the gait cycle).
"The implications of this study are that multiple forms of bi-pedalism were once practiced by our early hominin ancestors," adds Berger.
“What these papers suggest is that sediba probably doesn’t come from the east African species that Lucy comes from, Australopithecus afarensis, and it may be considered the best candidate as an ancestor for the genus Homo", says project leader Berger......Such clear insight into the anatomy of an early hominin species will clearly have implications for interpreting the evolutionary processes that affected the mode and tempo of hominin evolution and the interpretation of the anatomy of less well preserved species."
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Left: The U.W. 88-50 (MH 1) cranium. The cranium forms part of the holotype skeleton of Australopithecus sediba from the Malapa site, South Africa. This image relates to an article that appeared in the April 9, 2010, issue of Science, published by AAAS. The study, by Dr. L.R. Berger of University of the Witwatersrand in Johannesburg, South Africa, was titled, "Australopithecus sediba: A New Species of Homo-like Australopith from South Africa." Credit: Photo by Brett Eloff courtesy of Lee Berger and the University of the Witwatersrand.
OTHER FINDINGS FROM THE FIRST TWO YEARS
The Cranium Scan
The exceptionally well-preserved cranium of the MH-1 juvenile was scanned at the European Synchrotron Radiation Facility, the most powerful facility in the world for scanning fossils, under the direction of Dr. Kristian Carlson from the University of the Witwatersrand. By doing this, he and his colleagues were able to develop a precise map or image of the impressions on the interior surface of the cranium, or brain case, producing an endocast (or 3-dimensional image) of the area where the brain, long decayed into nothing, would have been.
Said Carlson, "the actual brain residing within a cranium does not fossilize. Rather, by studying the impressions on the inside of a cranium, palaeontologists have an opportunity to estimate what the surface of a brain may have looked like. By quantifying how much volume is contained within a cranium, palaeontologists can estimate the size of a brain."
The results revealed that the brain was human-like in shape, yet much smaller than brain volumes recorded in Homo species. In fact, the size was not significantly more than that of a modern chimpanzee. However, the orbito-frontal region of the brain, which is behind the eyes, showed characteristics of neural (nerve cell structure) reorganization. The researchers suggested that this indicated a “re-wiring” of the frontal lobe’s neural constitution to a pattern more human-like. This questioned the generally-accepted theory of brain enlargement during the transition from Australopithecus to Homo as the most essential consideration and supported the alternate theory that a neural reorganization in the orbitofrontal region made it possible for A. sediba to be more "human-like" with the smaller cranium. Thus, size may not matter more than brain tissue structure and organization.
The Hands and Toolmaking
Tracy Kivell of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and a team of colleagues studied the more complete hand fossils of MH-2, the adult female A. sediba.
They determined that the hand exhibited a strong flexor capability, good for tree-climbing. However, it also featured a long thumb and short fingers, a clear requirement for precision gripping, or gripping that involves the more refined use of the thumb and fingers and not the palm. This suggested that A. sediba had the mechanical capability to make tools.
According to Kivell:
"The hand is one of the very special features of the human lineage, as it's very different from the hand of the apes. Apes have long fingers for grasping branches or for use in locomotion, and thus relatively short thumbs that make it very difficult for them to grasp like a human.
Au. sediba has, in contrast, a more human-like hand that has shortened fingers and a very long thumb. Although at the same time, it appears to have possessed very powerful muscles for grasping. Our team interpreted this as a hand capable of tool manufacture and use, but still in use for climbing and certainly capable of human-like precision grip."
These findings pair A. sediba with Homo habilis, the famous "handy man" Australopithecine discovered by Louis and Mary Leakey in the 1960's, as a hominin or early human candidate capable of making tools. It also suggests that there were more than one ancient hominin species that may have produced tools, either during different time periods, overlapping time periods, or concurrently in time.
To date, no stone tools have been found in association with the Malapa cave fossils. But full-scale excavations have not yet taken place, and it is anticipated that much more data will be forthcoming as excavations are carried out in the near future.
The Pelvis
Dr. Job Kibii of the University of the Witwatersrand and associates examined the partial pelvis of MH-2 and found that it also exhibited features that combined primitive elements more akin to that of earlier hominins and apes along with elements more characteristic of humans. They observed that the size of the joint that connects the sacrum with the vertebral column and the length of the front portion of the pelvis is like that of earlier hominins and apes, but the overall shape of the pelvis is short and broad, creating a bowl shape like that of humans, with an s-shape along the top of the blades, another human characteristic. Indeed, simply placing the reconstructed pelvis next to that of an ape and an earlier hominin is very telling. The pelvis clearly appears more human-like than ape-like.
Says Kibii, “It is surprising to discover such an advanced pelvis in such a small-brained creature because of previous ideas as to the origin of the shape of the human pelvis”
The generally-accepted theory is that broader pelvises evolved, at least in part, in response to the enlarging brains of hominins, on the assumption that the more human-like pelvis shape more easily accommodated the larger-brained hominin infants in childbirth. The new findings turn this on its head, suggesting that there was another, perhaps more important evolutionary reason why the pelvis changed:
The change in the pelvic morphology accommodates a more bipedal, or erect, gate – a salient hallmark of being human. Says Steven Churchill of Duke University, one of the co-authors of the paper detailing the pelvis study, "What's cool about sediba is their pelvises are already different from other australopiths [early hominins], and yet they're still small-brained… It's hard to imagine that there's no change in locomotion behind all this."
The Feet and Ankles
Dr. Bernhard Zipfel of the University of the Witwatersrand and colleagues examined the feet and ankle fossils of MH-1 and MH-2, finding them to consist of a mix of both primitive and modern characteristics unique to A. sediba as a species. As the ankle fossils represented a very rare and opportune find in that they constituted one of the most complete hominin ankles ever found, and in an articulated position or association, it was feasible to perform a study and reach reasonably sound conclusions about the characteristics of the fossils and their implications. The ankle joint and foot bones were constructed much like a human's, with some evidence for a human-like arch and a well-defined Achilles tendon. It was also clear that the distal tibia or leg bone had to contact the anklebone perpendicular to the vertical shaft of the leg bone. These are all requirements for habitual bipedal locomotion, or upright walking.
However, the heel and shin bone exhibited more ape-like qualities, suggesting that A. sediba was also a tree-climber, much like its ape cousins.
The overall analysis suggested that A. sediba likely practiced a unique form of upright walking, not quite like that of humans, along with some degree of tree climbing.
To date, investigations at the Malapa site have seen the discovery of more than 300 early human ancestor remains, including parts of skeletons still encased in rock. Included in the recent discoveries are a new species of fox, named by the team as Vulpes skinneri just three months ago.
The six papers detailing the most recent studies are published in the 12 April 2013 issue of the journal Science, a publication of the American Association for the Advancement of Science.
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Composite reconstruction of Au. sediba based on recovered material from MH1, MH2 and MH4 and based upon the research presented in the accompanying manuscripts. As all individuals recovered to date are approximately the same size, size correction was not necessary. Femoral length was established by digitally measuring a complete femur of MH1 still encased in rock. For comparison, small-bodied female modern H. sapiens on left, Male Pan troglodytes on right. Credit: Photo by Lee Berger, courtesy of the University of the Witwatersrand
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Lee Berger with a partial skeleton of Australopithecus sediba. Photo by Brett Eloff, courtesy Lee Berger and the University of the Witwatersrand.
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Cover Photo, Top Left: The unusually complete skeletons of Australopithecus sediba discovered at the two million year old site of Malapa have already yielded a world of data, allowing more complete skeletal restorations than are usually possible with fossil hominins. Credit: Painting by John Gurche, courtesy of Lee Berger and the University of the Witwatersrand
http://popular-archaeology.com/issue/march-2013/article/scientists-find-groundbreaking-new-surprises-in-examination-of-early-human-ancestor
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| New Message Posted!2013-05-14 19:38
Brain size points to origins of 'hobbit'
A new study of fossil skulls has weighed into the debate on the identity of the ancestor of the so-called 'hobbit'.
Japanese researchers argue today in Proceedings of the Royal Society B that Homo erectus is the most likely predecessor of the famously diminuitive creature known as H. floresiensis.
"We conclude that evolution from early Javanese H. erectus to H. floresiensis was possible in terms of brain size," say Dr Yousuke Kaifu and colleagues, from the University of Tokyo and the National Museum of Nature and Science in Tokyo.
Ever since their discovery on the Indonesian island of Flores in 2004, bones of H. floresiensis have been the subject of much contention.
Some have claimed the so-called 'hobbit' was little more than a sick human, suffering from a condition called microcephaly.
While most working in this area support the idea that floresiensis is a new species of human, there is still quite broad disagreement over which early human it evolved from.
One hypothesis is that floresiensis evolved from the similarly small-bodied, small-brained H. habilis, but there is little evidence that such an ancestor ever made it to Southeast Asia.
Shrinking brain
Another theory is that the hobbit evolved from the much larger H. erectus, remains of which have been found on the island of Java.
According to this hypothesis, H. erectus somehow crossed over to Flores, where it shrunk into the hobbit over evolutionary time, through a process called "island dwarfism".
Weighing against this theory has been the gap between the sizes of the erectus and floresiensis brains.
But now, Kaifu and colleagues have used high-resolution CT scans to show the difference between the two is smaller than previously thought.
They say the earliest Javanese erectus had a brain size of 860 cubic centimetres, rather than the previously accepted mean of 991.
By contrast, floresiensis had a brain size of 426 cubic centimetres rather than the oft-cited figure of 400.
Together with a reanalysis of the scaling relationship between brain and body size among early humans, the researchers say the erectus model is now more viable.
They say while it is possible that the hobbit was an "archaic hominin individual with microcephaly … the robust limb bones, phalanges with osteophytes and signs of healed trauma on the cranial vault and tibia point to an active life rather than a disabled condition in this individual."
Scaling and extreme dwarfism
As humans and other hominins have evolved, their bodies have grown bigger, but their brains have grown at an even greater rate.
Researchers use such scaling relationship to work backwards and study evolutionary relationships between modern and early humans.
Using different groups of hominins and a larger sample than previously analysed, Kaifu and colleagues found this scaling could explain at least 50 per cent of the tiny hobbit brain.
"The results show more significant contribution of scaling effect than previously claimed," say Kaifu and colleagues.
The researchers say the rest of the shrinkage could be explained by extreme island dwarfism, in which the brain of an animal decreases in size even more compared to its body size.
For example, fossils show dwarf goats and hippos once lived on islands in the Mediterannean and off Africa.
The idea is that where there are no predators, and the animals are presumed not didn't have to use too much brain power to survive, they shed kilos of an organ which is very metabolically expensive.
Despite having to contend with giant storks, stegodons and komodo dragons, Kaifu and colleagues say the same could have applied to the hobbit.
Narrowing the gap
Professor Colin Groves of the Australian National University welcomes the research saying that although many CT scans of hobbit brain cases have been carried out before, Kaifu and colleagues have done the highest resolution yet.
Groves says the slightly larger hobbit brain size and the slightly smaller Homo erectus brain size "narrows the gap" between the two, but he is not convinced that erectus is the hobbit's most likely ancestor for the hobbit.
"I think habilis is the one it's most like," says Groves.
While he agrees fossil evidence for habilis is scant in Southeast Asia he says jaw fragments of the same age as the skulls being studied by Kaifu and colleagues suggest it was there long before floresiensis.
"The very earliest jaw fragments that are classified as H. erectus from Java have very habilis-like charactaristics and therefore could in fact be habilis," he says.
But everyone agrees that only more research will tell who is correct.
"The question will be answered most effectively by future discoveries of skeletal evidence for the first hominins to colonise Flores," say Kaifu and colleagues.
http://www.abc.net.au/science/articles/2013/04/17/3738441.htm?topic=ancient
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| New Message Posted!2013-05-14 14:21
Trove of Neanderthal Bones Found in Greek Cave
trove of Neanderthal fossils including bones of children and adults, discovered in a cave in Greece hints the area may have been a key crossroad for ancient humans, researchers say.
The timing of the fossils suggests Neanderthals and humans may have at least had the opportunity to interact, or cross paths, there, the researchers added.
Neanderthals are the closest extinct relatives of modern humans, apparently even occasionally interbreeding with our ancestors. Neanderthals entered Europe before modern humans did, and may have lasted there until about 35,000 years ago, although recent findings have called this date into question.
To learn more about the history of ancient humans, scientists have recently focused on Greece.
"Greece lies directly on the most likely route of dispersals of early modern humans and earlier hominins into Europe from Africa via the Near East," paleoanthropologist Katerina Harvati at the University of Tübingen in Germany told LiveScience. "It also lies at the heart of one of the three Mediterranean peninsulae of Europe, which acted as refugia for plant and animal species, including human populations, during glacial times — that is, areas where species and populations were able to survive during the worst climatic deteriorations."
"Until recently, very little was known about deep prehistory in Greece, chiefly because the archaeological research focus in the country has been on classical and other more recent periods," Harvati added.
Harvati and colleagues from Greece and France analyzed remains from a site known as Kalamakia, a cave stretching about 65 feet (20 meters) deep into limestone cliffs on the western coast of the Mani Peninsula on the mainland of Greece. They excavated the cave over the course of 13 years. [Amazing Caves: Photos Reveal Earth's Innards]
The archaeological deposits of the cave date back to between about 39,000 and 100,000 years ago to the Middle Paleolithic period. During the height of the ice age, the area still possessed a mild climate and supported a wide range of wildlife, including deer, wild boar, rabbits, elephants, weasels, foxes, wolves, leopards, bears, falcons, toads, vipers and tortoises.
In the cave, the researchers found tools such as scrapers made of flint, quartz and seashells. The stone tools were all shaped, or knapped, in a way typical of Neanderthal artifacts.
Now, the scientists reveal they discovered 14 specimens of child and adult human remains in the cave, including teeth, a small fragment of skull, a vertebra, and leg and foot bones with bite and gnaw marks on them. The teeth strongly appear to be Neanderthal, and judging by marks on the teeth, the ancient people apparently had a diet of meat and diverse plants.
"Kalamakia, together with the single human tooth from the nearby cave site of Lakonis, are the first Neanderthal remains to be identified from Greece," Harvati said. The discoveries are "confirmation of a thriving and long-standing Neanderthal population in the region."
These findings suggest "the fossil record from Greece potentially holds answers about the earliest dispersal of modern humans and earlier hominins into Europe, about possible late survival of Neanderthals and about one of the first instances where the two might have had the opportunity to interact," Harvati said.
In the future, Harvati and her colleagues will conduct new fieldwork in other areas in Greece to address mysteries such as potential coexistence and interactions between Neanderthals and modern humans, the spread of modern and extinct humans into Europe and possible seafaring capabilities of ancient humans.
"We look forward to exciting discoveries in the coming years," Harvati said.
The scientists detailed their findings online March 13 in the Journal of Human Evolution.
http://www.livescience.com/28326-neanderthal-remains-found.html
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| New Message Posted!2013-05-14 14:20
First Love Child of Human, Neanderthal Found
he skeletal remains of an individual living in northern Italy 40,000-30,000 years ago are believed to be that of a human/Neanderthal hybrid, according to a paper in PLoS ONE.
If further analysis proves the theory correct, the remains belonged to the first known such hybrid, providing direct evidence that humans and Neanderthals interbred. Prior genetic research determined the DNA of people with European and Asian ancestry is 1 to 4 percent Neanderthal.
The present study focuses on the individual’s jaw, which was unearthed at a rock-shelter called Riparo di Mezzena in the Monti Lessini region of Italy. Both Neanderthals and modern humans inhabited Europe at the time.
PHOTOS: Faces of Our Ancestors
“From the morphology of the lower jaw, the face of the Mezzena individual would have looked somehow intermediate between classic Neanderthals, who had a rather receding lower jaw (no chin), and the modern humans, who present a projecting lower jaw with a strongly developed chin,” co-author Silvana Condemi, an anthropologist, told Discovery News.
Condemi is the CNRS research director at the University of Ai-Marseille. She and her colleagues studied the remains via DNA analysis and 3D imaging. They then compared those results with the same features from Homo sapiens.
The genetic analysis shows that the individual’s mitochondrial DNA is Neanderthal. Since this DNA is transmitted from a mother to her child, the researchers conclude that it was a “female Neanderthal who mated with male Homo sapiens.”
NEWS: Neanderthals Lacked Social Skills
By the time modern humans arrived in the area, the Neanderthals had already established their own culture, Mousterian, which lasted some 200,000 years. Numerous flint tools, such as axes and spear points, have been associated with the Mousterian. The artifacts are typically found in rock shelters, such as the Riparo di Mezzena, and caves throughout Europe.
The researchers found that, although the hybridization between the two hominid species likely took place, the Neanderthals continued to uphold their own cultural traditions.
That's an intriguing clue, because it suggests that the two populations did not simply meet, mate and merge into a single group.
NEWS: Neanderthals Died Out Earlier Than Thought
As Condemi and her colleagues wrote, the mandible supports the theory of "a slow process of replacement of Neanderthals by the invading modern human populations, as well as additional evidence of the upholding of the Neanderthals' cultural identity.”
Prior fossil finds indicate that modern humans were living in a southern Italy cave as early as 45,000 years ago. Modern humans and Neanderthals therefore lived in roughly the same regions for thousands of years, but the new human arrivals, from the Neanderthal perspective, might not have been welcome, and for good reason. The research team hints that the modern humans may have raped female Neanderthals, bringing to mind modern cases of "ethnic cleansing."
Ian Tattersall is one of the world’s leading experts on Neanderthals and the human fossil record. He is a paleoanthropologist and a curator emeritus at the American Museum of Natural History.
Tattersall told Discovery News that the hypothesis, presented in the new paper, “is very intriguing and one that invites more research.”
Neanderthal culture and purebred Neanderthals all died out 35,000-30,000 years ago.
http://news.discovery.com/human/evolution/neanderthal-skeleton-provides-evidence-of-interbreeding-with-humans-130327.htm
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| New Message Posted!2013-05-14 14:04
Ancient DNA reveals humans living 40,000 years ago in Beijing area related to present-day Asians, Native Americans
An international team of researchers including Svante Pääbo and Qiaomei Fu of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, sequenced nuclear and mitochondrial DNA that had been extracted from the leg of an early modern human from Tianyuan Cave near Beijing, China. Analyses of this individual's DNA showed that the Tianyuan human shared a common origin with the ancestors of many present-day Asians and Native Americans. In addition, the researchers found that the proportion of Neanderthal and Denisovan-DNA in this early modern human is not higher than in people living in this region nowadays.
Humans with morphology similar to present-day humans appear in the fossil record across Eurasia between 40,000 and 50,000 years ago. The genetic relationships between these early modern humans and present-day human populations had not yet been established. Qiaomei Fu, Matthias Meyer and colleagues of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, extracted nuclear and mitochondrial DNA from a 40,000 year old leg bone found in 2003 at the Tianyuan Cave site located outside Beijing. For their study the researchers were using new techniques that can identify ancient genetic material from an archaeological find even when large quantities of DNA from soil bacteria are present.
The researchers then reconstructed a genetic profile of the leg's owner. "This individual lived during an important evolutionary transition when early modern humans, who shared certain features with earlier forms such as Neanderthals, were replacing Neanderthals and Denisovans, who later became extinct", says Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology, who led the study.
The genetic profile reveals that this early modern human was related to the ancestors of many present-day Asians and Native Americans but had already diverged genetically from the ancestors of present-day Europeans. In addition, the Tianyuan individual did not carry a larger proportion of Neanderthal or Denisovan DNA than present-day people in the region. "More analyses of additional early modern humans across Eurasia will further refine our understanding of when and how modern humans spread across Europe and Asia", says Svante Pääbo.
Parts of the work were carried out in a new laboratory jointly run by the Max Planck Society and the Chinese Academy of Sciences in Beijing.
Read more at: http://phys.org/news/2013-01-ancient-dna-reveals-humans-years.html#jCp
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| New Message Posted!2013-05-14 14:03
Out of Africa date brought forward
A study on human mitochondrial DNA has led to a new estimate of the time at which humans first began to migrate out of Africa, which was much later than previously thought.
The new study by an International group of evolutionary geneticists used mitochondrial DNA from the remains of ancient modern humans to estimate the rate of genetic mutations. Three of the skeletons were from the Czech Republic and dated at 31,000 years old, two were 14,000 years old, from Oberkassel, Germany. Another sample used was the natural mummy Ötzi the Iceman, who lived some time between 3350 and 3100 BC. The most recent skeleton was that of a man who lived in medieval France 700 years ago, while the oldest was dated at 40,000 years ago, and came from Tianyuan in China.
The results suggest that the genetic divergence between African and non-African humans began between 62 and 95 thousand years ago, which tallies with other studies estimating the time through dating of stone tools and fossils, but they disagree with the results of recent genetic studies that estimated the migration began much earlier, up to 130 thousand years ago or even before.
The previous studies sequenced the entire genome of living humans to count the number of genetic mutations (around 50) in newborn babies compared to the parents to determine the generational mutation rate. This then provided the a molecular "clock," which could be extrapolated backwards to date important events in human evolution.
The new study sequenced mitochondrial DNA from fossils of ancient modern humans rather than living humans. The fossils were dated using radiocarbon dating methods. Since the samples were from humans who lived up to 40,000 years ago, mutations that have occurred in the genome since they died would be missing, and the samples provided a range of calibration points for their estimation of the start of the migration.
The disagreement in dating the migration between the new study and previous genetic research could be due to underestimating the number of new mutations in a generation of living humans because of the difficulty of discriminating between true mutations and mistaken ones and because of a desire to avoid false positives. Under-counting would lead to an older estimate for the migration from Africa and other important events.
The new date, which agrees with the archaeological evidence, shows that modern humans were in Europe and Asia before and after the most recent glaciation, and they were therefore able to survive and adapt to a dramatically changing climate.
The paper was published in the journal Current Biology on 21st March.
Read more at: http://phys.org/news/2013-03-africa-date-brought.html#jCp
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| New Message Posted!2013-05-14 13:43
Early hominins couldn't have heard modern speech
Our australopith ancestors heard their world differently from modern humans.
Rolf Quam at Binghamton University in New York State and colleagues have discovered rare middle ear bones from two extinct southern African hominins – Australopithecus africanus and Paranthropus robustus.
A combination of ape-like and human-like features in the bones indicate some australopiths lacked sensitivity to the midrange frequencies that modern humans use for speech.
"Anthropologists are in general agreement that these early hominins likely did not possess spoken language," says Quam – the new findings back that claim.
His team now plans to use CT scans of the fossils and 3D virtual reconstruction of the ear anatomy to work out more precisely what the world sounded like to our distant ancestors.
Journal reference: PNAS, DOI: 10.1073/pnas.1303375110
http://www.newscientist.com/article/dn23532-early-hominins-couldnt-have-heard-modern-speech.html
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