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coldrum
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|  Posted 04-09-2012 at 14:25
Denisovan DNA suggests a dark complexion and interbreeding
Scientists have reconstructed the whole genetic code, or genome, of a group of ancient humans called Denisovans. They interbred with our species and the DNA results suggest they had dark hair, eyes, and skin, the journal Science reports.
In 2010, scientists from the Max Planck Institute in Germany announced the new human group based on DNA evidence from a finger bone fossil found in Denisova Cave in the Altai Mountains, Siberia.
That first DNA was obtained from mitochondria, tiny power structures in each human cell that contain their own DNA. Now, many of the same team have used a new approach and have sequenced chromosomal DNA (the DNA of the cell nucleus which contains most genes) from the same finger bone fossil.
'They were able to reconstruct the whole genome to a quality matching that obtained for living humans,' says Professor Chris Stringer, human origins expert at the Natural History Museum.
'The higher quality genome not only provides greater confidence about previous conclusions, but also adds many details about the Denisovans, and how modern humans may have differed from them,' adds Stringer.
Skull of Homo heidelbergensis, the ancient human species that may be ancestor of mystery Denisova
Skull of Homo heidelbergensis, the ancient human species that may be the ancestor of the mystery Denisovan human.
'The research confirms that the Denisovans were related to the Neanderthals, and that many present-day Australasians have Denisovan DNA from an ancient interbreeding event.'
Some theories place Denisovans, along with Neanderthals and modern humans, as the descendents of the ancient human Homo heidelbergensis who lived about 500,000 years ago.
Potential biological differences
By comparing the genomes of Denisovans, apes, Neanderthals and different modern human populations, the team could identify DNA segments unique to these different groups.
This may help shed light on potential biological differences between modern humans and the Neanderthal and Denisovan populations they replaced, Stringer says.
For example, in modern humans, unique segments were associated with brain function and nervous system development, as well as diseases affecting the skin and eyes.
'Perhaps some of the skin and eye-related ones reflect resistance to diseases in the African homeland of modern humans, but the brain-related ones hint at possible enhancements in brain structure and function in our species.'
Two Neanderthal interbreeding events?
Skull of a Neanderthal, Homo neanderthalensis
Skull of a Neanderthal, Homo neanderthalensis
The Denisovan genome also reveals more clues about Denisovan and Neanderthal interbreeding with modern humans. Until now, evidence suggested that after modern humans dispersed from Africa about 60,000 years ago, there was a single interbreeding event with Neanderthals.
'Previous research suggested that all recent populations originating from outside of Africa had received about the same amount of Neanderthal input, implying a single early hybridisation event somewhere like the Middle East,' says Stringer.
However, the results of this study show that the Neanderthal genetic input to modern human populations outside of Africa varies. 'This suggests that, overall, Europeans have less Neanderthal DNA (about 1%) than populations to the east (1.7%),' explains Stringer.
'This might imply changes in the proportions after interbreeding took place, or that there was more than one interbreeding event.'
Denisovan interbreeding confirmation
The team found that the Denisovan genetic input in Australasian populations averaged about 3%. 'This supports the idea that Denisovans must have been present in south east Asia, where the hypothesised interbreeding with the ancestors of present-day Australasians occurred, as well as in Siberia,' says Stringer.
Low genetic diversity
Our genes often come in different variants, such as those for skin colour or eye colour and a large population will generally hold more variation than a small population. But, the Denisovan DNA results showed very low diversity, much less than a single modern human would show, says Stringer.
'This is surprising because the previous mitochondrial DNA research had suggested relatively high diversity, and interbreeding with the ancestors of Australasians (who are thought to have passed through southern Asia rather than Siberia) implied that the Denisovans were widespread in Asia, also leading to the expectation of a large and diverse population.'
'The surprisingly low genetic diversity of the Denisovans may indicate, as with Neanderthals to the west, that the core territory of the Denisovans was well to the south, and that they only expanded to regions like the Altai during brief warm intervals, and in small numbers.'
Other physical features
Apart from the genetic evidence of a dark complexion, Stringer says we need to find out more about what the Denisovans looked like physically. 'This will require the recovery of ancient DNA from more complete fossils, perhaps in Denisova Cave itself, or from specimens in regions like China,’ he says.
'The genome does not tell us how big their brains or brow ridges were, if they had chins, or how tall and robust they were. Hence we need to have Denisovan DNA from more complete fossils to link the genome to morphology'.
Function of shared DNA
Stringer says that further research should also help explain what function, if any, the Denisovan and Neanderthal DNA has in the modern humans that hold it.
More interbreeding
Finally, there is an issue that perhaps cannot be addressed properly until higher quality reconstructions of Neanderthal genomes also become available, says Stringer. If modern humans interbred successfully with both Neanderthals and Denisovans, did Neanderthals and Denisovans interbreed?
Stringer thinks this is likely. 'It seems highly probable that they did, given that they co-existed in Eurasia for hundreds of millennia, and Denisova cave itself has evidence of Neanderthal DNA in a fossil foot bone.'
Stringer concludes, 'Recognition of such interbreeding will inevitably complicate the untangling of the relationships between these ancient groups of humans, and their contributions to people today.'
http://www.nhm.ac.uk/about-us/news/2012/august/denisovan-dna-suggests-a-dark-complexion-and-interbreeding113697.html
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coldrum
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| Posted 04-09-2012 at 14:32
Neanderthal sex debate highlights benefits of pre-publication — UPDATED
An argument over sex that has been going on for more than a year is finally seeing the light of day. Today, scientists at the University of Cambridge, UK, and Harvard Medical School in Boston, Massachusetts, let the world in on a long-running discussion over whether or not humans and Neanderthals really interbred — and how you go about proving it.
I’ll get to the sex. But this debate underscores a topic I wrote about last month (see ‘Geneticists eye the potential of ArXiv‘) that noted that high-profile papers from population geneticists are beginning to appear on the preprint server, once the domain just of theoretical physicists. That story is relevant because a new paper, entitled ‘The date of interbreeding between Neandertals and modern humans’, was posted to ArXiv on Friday. Meanwhile, a second paper raising doubts about human-Neanderthal hanky-panky appears in the Proceedings of the National Academy of Sciences (PNAS) today.
Both papers were presented at conferences more than a year ago. Their publication today raises the question of whether this debate would have been more timely if it had occurred on preprint servers such as ArXiv.org and not at specialist conferences and behind the walls of peer review.
In putting a date — 37,000–86,000 years ago — on human–Neanderthal relations, Harvard’s David Reich attempts to address a question created when he and his co-author Svante Pääbo, of the Max Planck Institute of Evolutionary Anthropology in Leipzig, Germany, published a draft sequence of the Neanderthal genome in 2010.
Just about every science reporter (see ‘European and Asian genomes have traces of Neanderthal‘, for example) led with the conclusion that Neanderthals and non-African humans had interbred.
But Pääbo, Reich and their co-authors said that there could be another explanation for their observation that all non-Africans surveyed (that is people with deep Asian and European ancestry) owed about 1–4% of their genome to Neanderthals, while African genomes contain no detectable Neanderthal DNA. Neanderthals and humans share an ancestor that lived in Africa about half a million years ago. It is possible that modern non-African’s Neanderthal DNA dates to the time of these early humans — and not more recent escapades. By chance or quirk of geography, the humans who left Africa could have been more closely related to Neanderthals than the humans who stayed behind.
In other words, it only looks like humans and Neanderthals interbred when we compare their genomes, but 500,000-year-old population structure in Africa is the real explanation. Anders Eriksson and Andrea Manica, at Cambridge, elaborate on this scenario in their new PNAS paper.
Not so, say Reich and Pääbo in their ArXiv paper, which reports a nifty new method for determining when two populations interbred. It’s based on the fact that our maternal and paternal chromosomes reshuffle after each generation. This mixing makes the contiguous chunks smaller with each generation. Reich and his colleague Sriram Sankararaman take advantage of this feature to conclude that humans and Neanderthals interbred between 37,000 and 86,000 years ago, and probably more like 47,000–65,000 years ago.
Reich tells Nature that the paper will soon be published in PLoS Genetics. Meanwhile, Monty Slatkin’s team at the University of California, Berkeley, came to a similar conclusion to Reich’s using a different method. They published their results in April and presented them at a conference last summer.
Fair enough, one might say, this is how science works. One paper raises questions that are addressed by others. But Reich believes that the discussion would have been different if it had happened in the open. The PNAS paper questioning the Neanderthal admixture addresses issues swirling around two years ago, but not Reich and Slatkin’s latest work. “It’s been an issue for several years. They were right to work on this,” says Reich. But now, “it’s kind of an obsolete paper,” he says.
Manica says that more data are needed to reach any firm conclusion on human–Neanderthal relations. “I think one take-home message is that establishing the presence and strength of hybridization is far from trivial if you only have one Neanderthal genome.” He supports pre-publication, in theory. “The problem is that papers are not routinely uploaded as soon as they are ready, as it the case in physics. So, for ArXiv to be functional, everyone needs to upload their drafts on a regular basis.”
Reich, who posted another high-profile paper on the genetic history of southern Africans to ArXiv two weeks ago, thinks this debate would have been different if geneticists routinely posted to preprint servers. The conversation could be happening in near real-time and not with a two-year lag. “We think there’s no reason not to [post to ArXiv] and it’s interesting for other people to read about that work,” Reich says. “Maybe it would have been helpful in this context as well.”
http://blogs.nature.com/news/2012/08/neanderthal-sex-debate-highlights-benefits-of-pre-publication.html
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coldrum
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| Posted 04-09-2012 at 14:45
Evolution of Humans in Europe More Complex Than Previously Thought
Tue, Aug 14, 2012
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Many factors shaped the course of human evolution on the European subcontinent, say researchers.
Evolution of Humans in Europe More Complex Than Previously Thought
Nothing is as simple as it looks, as the saying goes. And it seems to apply as well to the picture of how humans evolved in present-day Europe, if recent studies and advances in genetic research have any say. In a report just published in the Cell Press journal, Trends in Genetics, the authors maintain that advances in analytical techniques and genetic applications are up-ending long-held, simplistic views about European human evolutionary history. Findings and analyses are indicating that there were actually many climatic, demographic and cultural events and a diverse group of mechanisms that worked together over time to shape the genetic variation we see today among modern Europeans.
"We are currently at a stage in which next-generation sequencing technologies, ancient DNA analyses, and computer simulation modeling allow us to obtain a much more accurate and detailed perspective on the nature and timing of major prehistoric processes such as the colonization of Europe by modern humans, the survival of human populations during the Ice Age, the Neolithic transition, and the rise and fall of complex societies and empires," says author Dr. Ron Pinhasi of Trinity College in Dublin, Ireland. "These methods and technologies hold great potential to shed new light on past genetic variation, the onset of major cultural and technological changes that left their imprint on past and present genomes, and potentially on the impact of changes in lifestyle and demography on the appearance of certain diseases and genetic disorders."
Following the height of the Ice Age (from 27,000 to 16,000 years ago), hunter-gatherer groups began to re-populate most parts of Europe. Then, about 8,000 years ago, farming populations began to make their presence on the continent during the "Neolithic transition". For several thousand years, two distinctly different modes of life coexisted across Europe: hunter-gatherer populations, relying on food resources obtained in the wild, and farming populations, practicing domesticated crops, livestock, pottery-making, housing, and storage techniques.
It has long been theorized that European human genetic diversity formed during the Neolithic transition; But now, scientists (at least those involved in this report) suggest that it was also shaped before and after the transition. In addition, they write, the expansion of farming is likely to have varied by region, resulting in a more complex mix of farmers' and local hunter-gatherers' genetic contributions to European populations.
The changing approach to researching human prehistory has made a profound difference in the efforts to understand the human evolutionary past. Says co-author Dr. Mathias Currat: "The development of inter-disciplinary approaches is crucial to elaborate realistic models of human evolution." explains Dr. Mathias Currat. http://popular-archaeology.com/issue/june-2012/article/evolution-of-humans-in-europe-more-complex-than-previously-thought
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coldrum
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| Posted 04-09-2012 at 14:47
Peking Man World Heritage Site Among 160 Sites Damaged in Beijing Floods
By Heritage on the Wire Sun, Aug 12, 2012
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Dig site endangered by potential landslide.
Peking Man World Heritage Site Among 160 Sites Damaged in Beijing Floods
Beijing’s heaviest rainfall in six decades has affected 160 heritage sites, including the Peking Man World Heritage Site at Zhoukoudian, according to the city’s Municipal Administration of Cultural Heritage. In addition, at least 77 people died as a result of the storms, which have again raised questions about Beijing’s infrastructure, especially its antiquated drainage network.
At the Peking Man site, the deluge caused several minor landslides, disabled the site’s security system, and flooded a museum (no major exhibits were reportedly harmed). Dirt and mud covered part of the archaeological dig at Zhoukoudian, halting researchers’ work for at least three days, according to Zhang Shuangquan, a Chinese archaeologist who has been excavating the site since 2009.
In an interview with China Daily, Zhang said he was most concerned about a potentially bigger landslide destroying the whole dig site, which is located on a cliff. The site is currently covered with plastic sheets, but it is the stratum at the top of the mountain — which is uncovered — that concerns Zhang the most. If the rock stratum were to collapse, the site would lose much of its archaeological value, since researchers learn how people lived in the past by taking account of the depth of objects and human remains embedded in the soil.
“The geological movement is very slow, but it might reach a breaking point at any moment, maybe tomorrow or 10 years from now,” Zhang said. “[If this happened,] a period of human civilization would be buried in mystery forever.”
Zhoukoudian, which attracts some 120,000 visitors and researchers every year, was discovered in 1921 by the Swedish archaeologist Johan Gunnar Andersson. Since then, it has been the site of many archaeological discoveries, including one of the first specimens of Homo erectus, dubbed Peking Man (fossil skull and endocast reconstruction pictured right). Some of the human and animal remains found at the site date back some 750,000 years. In 1987, the site was inscribed to the UNESCO World Heritage List.
While none of the recent damage to Zhoukoudian was severe, the flooding will hopefully convince Chinese cultural authorities of the need for a better site protection plan.http://popular-archaeology.com/issue/june-2012/article/peking-man-world-heritage-site-among-160-sites-damaged-in-beijing-floods
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coldrum
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| Posted 04-09-2012 at 14:50
Multiple Species of Early Homo Lived in Africa
In March, I compiled a list of my top ten hominid fantasy finds. Item number six: more Homo habilis and Homo rudolfensis fossils. The two species are the oldest members of the genus Homo. H. habilis lived roughly 2.4 million to 1.4 million years ago while H. rudolfensis lived about 2 million years ago. But where some scientists see two contemporaneous species, others recognize just one. These researchers say the fossils of H. rudolfensis may simply represent physical variation within the H. habilis species due to differences based on geography or sex. It’s a hard question to answer as there’s only really one good H. rudolfensis fossil.
But as it turns out, fantasies really can come true: A team of researchers announced today in Nature that they’ve dug up three new fossils that match the lone H. rudolfensis specimen. The new finds confirm that at least two species of Homo lived in Africa 2 million years ago.
In the 1960s, Louis and Mary Leakey discovered the species H. habilis while working at Tanzania’s Olduvai Gorge. In 1972, Bernard Ngeneo, a member of a team led by the Leakeys’ son Richard, discovered a 2-million-year-old skull lacking a lower jaw at Kenya’s Koobi Fora site near Lake Turkana. The skull, known as KNM-ER 1470, sort of looked like H. habilis, but was different in several key ways, such as being much bigger with a flatter face. Some anthropologists suggested the skull belonged to a male H. habilis and that’s why it was bigger. Other researchers said the differences were too great to be explained by sex, and they gave the skull the name H. rudolfensis because Lake Turkana was once known was Lake Rudolf.
The three new fossils also come from Koobi Fora, dating to 1.78 million to 1.95 million years ago. They also have a connection to the Leakeys. Meave Leakey, a paleontologist at the Turkana Basin Institute, is married to Richard Leakey, and Louise Leakey, Meave and Richard’s daughter, led the team that made the discoveries.
The fossil KNM-ER 62000 is the face of a juvenile. Although much smaller than the KNM-ER 1470 skull, both fossils share the same shape and features. The researchers say this is evidence that H. rudolfensis was a separate species rather than being the male version of H. habilis. The other two fossil finds are of lower jaws, which seem to match the shape of the upper jaws of KNM-ER 1470 and KNM-ER 62000. This further suggests that H. rudolfensis is indeed a separate species because the new jaws are much different from known H. habilis jaws: They are shorter and more rectangular.
One of the lower jaws recently unearthed at Koobi Fora, Kenya. Image: © Photo by Mike Hettwer, http://www.hettwer.com, courtesy of National Geographic
The team doesn’t outright say that the new fossils plus KMN-ER 1470 should officially be called H. rudolfensis. They’re cautious because of a fossil lower jaw from Olduvai Gorge called OH 7. OH 7 is the type specimen of H. habilis—in other words, it’s the fossil that scientists use to define the species. But the fossil is very distorted. If scientists were to reanalyze the jaw and discover it actually belongs in the same species as the newly found jaws, then by the rules of taxonomy, researchers would have to call that species H. habilis. And then the species we now call H. habilis would need a new name. (Let’s hope that doesn’t happen because it would be very confusing.)
Regardless of what the fossils are called, scientists now have much better evidence that two species of Homo lived in Africa at the beginning of the Pleistocene. That number grew to three species with the emergence of Homo erectus 1.89 million years ago. Now there are new questions to ponder. Were H. habilis and H. rudolfensis both dead ends? Did H. erectus descend from one of these species or a currently unknown member of Homo?
It looks like I have some new stuff to add to my list of hominid fantasy finds for next year.
http://blogs.smithsonianmag.com/hominids/2012/08/multiple-species-of-early-homo-lived-in-africa/
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coldrum
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| Posted 04-09-2012 at 14:55
Fossils point to a big family for human ancestors
Jaw structures suggest that at least three Homo species once roamed the African plains.
Matt Kaplan
08 August 2012
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Fossilized skulls show that at least three distinct species belonging to the genus Homo existed between 1.7 million and 2 million years ago, settling a long-standing debate in palaeoanthropology.
A study published this week in Nature1 focuses on Homo rudolfensis, a hominin with a relatively flat face, which was first identified from a single large skull in 1972. Several other big-skulled fossils have been attributed to the species since then, but none has included both a face and a lower jaw. This has been problematic: in palaeoanthropology, faces and jaws function like fingerprints for identifying a specimen as a particular species (which is indicated by the second word in a Linnaean title, such as 'rudolfensis'), as opposed to the broader grouping of genus (the first word, as in'Homo').
An upper skull found in 1972 and a newly discovered lower jaw are both thought to belong to the enigmatic hominin species Homo rudolfensis.
F. Spoor
Without complete skulls, it has been difficult to reach a consensus on whether specimens attributed to H. rudolfensis are genuinely members of a distinct species, or actually belong to other Homo species that lived around the same time, such as Homo habilis or Homo erectus. Understanding how many different Homo species there were, and whether they lived concurrently, would help to determine whether the history of the human lineage saw fierce competition between multiple hominins, or a steady succession from one species to another.
But the latest result has dissipated much of this uncertainty. It concerns three fossils — two lower jaws and a juvenile’s lower face — that were found in a desert area called Koobi Fora in northern Kenya. The team that pulled them out of the ground, led by Meave Leakey, a palaeontologist at the Turkana Basin Institute in Nairobi, describes how the dental arcade, the arch created by the teeth at the front of the mouth, is nearly rectangular, just like the palate structure of the 1972 skull. By contrast, the average modern human mouth has a curved dental arcade.
Further evidence comes from the juvenile’s face, which tellingly has cheek bones joining the palate quite far forward. “It was such an extended excitement as the juvenile face slowly emerged from the encasing rock, and its similarity to the 1972 specimen became so striking,” recalls Leakey.
Historical likeness
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Yet in many ways, the team’s findings present more questions than answers.
One known lower-jaw specimen, dubbed KNM-ER 1802 and widely considered to belong to an individual H. rudolfensis, seems to have a more rounded dental arcade than the latest fossils. This has led Leakey and her colleagues to propose that KNM-ER 1802 belongs to a different Homo species — possibly H. habilis. But until more H. habilis bones are found, the team cannot be sure. “It could be a Homo habilis, but it could also be another species,” says Bernard Wood, a palaeontologist at George Washington University in Washington DC.
With as many as four Homo species (H. rudolfensis, H. habilis, H. erectus and whatever KNM-ER 1802 turns out to be) co-existing in one period of evolutionary history, researchers are wondering how different hominins may have behaved in each other's company.
“Because the geologic dating is so coarse, we can’t yet be entirely certain that these species were in the same places at the same times," says Wood. "Even so, it is perfectly possible that they were interacting — and if that was so, boy, wouldn’t we like to know what those interactions were like."
However, Tim White, a palaeontologist at the University of California, Berkeley, argues that Leakey and her colleagues are putting the cart before the horse. “How can practitioners in this field possibly expect to be able to accurately identify fossil species based upon a few teeth, jaws and lower faces in light of what we know about the great variation found among different individuals in a single living species?” he asks.
Leakey stands her ground. “I would challenge Tim to find any primate in which you would see the same degrees of variation as those that we are seeing between our new fossils and KNM-ER 1802," she retorts.
http://www.nature.com/news/fossils-point-to-a-big-family-for-human-ancestors-1.11144
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coldrum
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| Posted 04-09-2012 at 14:59
New Kenyan Fossils Shed Light On Early Human Evolution
ScienceDaily (Aug. 8, 2012) — Exciting new fossils discovered east of Lake Turkana confirm that there were two additional species of our genus -- Homo -- living alongside our direct human ancestral species, Homo erectus, almost two million years ago. The finds, announced in the scientific journal Nature on August 9th, include a face, a remarkably complete lower jaw, and part of a second lower jaw.
They were uncovered between 2007 and 2009 by the Koobi Fora Research Project (KFRP), led by Meave and Louise Leakey. KFRP's fieldwork was facilitated by the Turkana Basin Institute (TBI), and supported by the National Geographic Society, which has funded the KFRP since 1968.
Four decades ago, the KFRP discovered the enigmatic fossil known as KNM-ER 1470 (or "1470" for short). This skull, readily distinguished by its large brain size and long flat face, ignited a longstanding debate about just how many different species of early Homo lived alongside Homo erectus during the Pleistocene epoch. 1470's unusual morphology was attributed by some scientists to sexual differences and natural degrees of variation within a single species, whereas others interpreted the fossil as evidence of a separate species.
This decades-old dilemma has endured for two reasons. First, comparisons with other fossils have been limited due to the fact that 1470's remains do not include its teeth or lower jaw. Second, no other fossil skull has mirrored 1470's flat and long face, leaving in doubt just how representative these characteristics are. The new fossils address both issues.
"For the past 40 years we have looked long and hard in the vast expanse of sediments around Lake Turkana for fossils that confirm the unique features of 1470's face and show us what its teeth and lower jaw would have looked like," says Meave Leakey, co-leader of the KFRP and a National Geographic Explorer-in-Residence. "At last we have some answers."
"Combined, the three new fossils give a much clearer picture of what 1470 looked like," says Fred Spoor, leader of the scientific analyses. "As a result, it is now clear that two species of early Homo lived alongside Homo erectus. The new fossils will greatly help in unraveling how our branch of human evolution first emerged and flourished almost two million years ago."
Found within a radius of just over 10 km from 1470's location, the three new fossils are dated between 1.78 million and 1.95 million years old. The face KNM-ER 62000, discovered by field crew member Elgite Lokorimudang in 2008, is very similar to that of 1470, showing that the latter is not a single "odd one out" individual. Moreover, the face's well-preserved upper jaw has almost all of its cheek teeth still in place, which for the first time makes it possible to infer the type of lower jaw that would have fitted 1470. A particularly good match can be found in the other two new fossils, the lower jaw KNM-ER 60000, found by Cyprian Nyete in 2009, and part of another lower jaw, KNM-ER 62003, found by Robert Moru in 2007. KNM-ER 60000 stands out as the most complete lower jaw of an early member of the genus Homo yet discovered.
The team working on the new finds included Christopher Kiarie (TBI), who carried out the laboratory preparation of the fossils, Craig Feibel (Rutgers University), who studied the age of the fossils, and Susan Antón (New York University), Christopher Dean (UCL, University College London), Meave and Louise Leakey (TBI, Kenya; and Stony Brook University, New York) and Fred Spoor (Max Planck Institute for Evolutionary Anthropology, Leipzig and UCL), who analyzed the fossils. The National Geographic Society funded the fieldwork, the Leaky Foundation funded geological studies, and the Max Planck Society supported laboratory work.
TBI is a privately funded, non-profit initiative founded by Richard Leakey and Stony Brook University, New York, that seeks to facilitate multi-disciplinary fieldwork within the Lake Turkana Basin in affiliation with the National Museums of Kenya. The primary research focus is human prehistory and related earth and natural science studies. For more information, visit TBI at: http://www.turkanabasin.org/discovery/knmer60000/http://www.sciencedaily.com/releases/2012/08/120808132705.htm
[ This message was edited by: bat400 on 2013-01-02 20:58 ]
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sem
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| Posted 24-10-2012 at 01:01
Hi Coldrum / Bat400
This gives a pretty good overview of everything posted.
http://www.bbc.co.uk/iplayer/episode/p00xfdmw/Prehistoric_Autopsy_Neanderthal/
It's about 1hr long.
Not sure which one of you is the blond piece but she wiggles far better than Neil Oliver.
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coldrum
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| Posted 13-05-2013 at 18:56
Earliest Archaeological Evidence of Human Ancestors Hunting and Scavenging
A recent Baylor University research study has shed new light on the diet and food acquisition strategies of some the earliest human ancestors in Africa.
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Beginning around two million years ago, early stone tool-making humans, known scientifically as Oldowan hominin, started to exhibit a number of physiological and ecological adaptations that required greater daily energy expenditures, including an increase in brain and body size, heavier investment in their offspring and significant home-range expansion. Demonstrating how these early humans acquired the extra energy they needed to sustain these shifts has been the subject of much debate among researchers.
A recent study led by Joseph Ferraro, Ph.D., assistant professor of anthropology at Baylor, offers new insight in this debate with a wealth of archaeological evidence from the two million-year-old site of Kanjera South (KJS), Kenya. The study's findings were recently published in PLOS One.
"Considered in total, this study provides important early archaeological evidence for meat eating, hunting and scavenging behaviors -cornerstone adaptations that likely facilitated brain expansion in human evolution, movement of hominins out of Africa and into Eurasia, as well as important shifts in our social behavior, anatomy and physiology," Ferraro said.
Located on the shores of Lake Victoria, KJS contains "three large, well-preserved, stratified" layers of animal remains. The research team worked at the site for more than a decade, recovering thousands of animal bones and rudimentary stone tools.
According to researchers, hominins at KJS met their new energy requirements through an increased reliance on meat eating. Specifically, the archaeological record at KJS shows that hominins acquired an abundance of nutritious animal remains through a combination of both hunting and scavenging behaviors. The KJS site is the earliest known archaeological evidence of these behaviors.
"Our study helps inform the 'hunting vs. scavenging' debate in Paleolithic archaeology. The record at KJS shows that it isn't a case of either/or for Oldowan hominins two million years ago. Rather hominins at KJS were clearly doing both," Ferraro said.
The fossil evidence for hominin hunting is particularly compelling. The record shows that Oldowan hominins acquired and butchered numerous small antelope carcasses. These animals are well represented at the site by most or all of their bones from the tops of their head to the tips of their hooves, indicating to researchers that they were transported to the site as whole carcasses.
Many of the bones also show evidence of cut marks made when hominins used simple stone tools to remove animal flesh. Some bones also bear evidence that hominins used fist-sized stones to break them open to acquire bone marrow.
In addition, modern studies in the Serengeti--an environment similar to KJS two million years ago--have also shown that predators completely devour antelopes of this size within minutes of their deaths. As a result, hominins could only have acquired these valuable remains on the savanna through active hunting.
The site also contains a large number of isolated heads of wildebeest-sized antelopes. In contrast to small antelope carcasses, the heads of these somewhat larger individuals are able to be consumed several days after death and could be scavenged, as even the largest African predators like lions and hyenas were unable to break them open to access their nutrient-rich brains.
"Tool-wielding hominins at KJS, on the other hand, could access this tissue and likely did so by scavenging these heads after the initial non-human hunters had consumed the rest of the carcass," Ferraro said. "KJS hominins not only scavenged these head remains, they also transported them some distance to the archaeological site before breaking them open and consuming the brains. This is important because it provides the earliest archaeological evidence of this type of resource transport behavior in the human lineage."
Other contributing authors to the study include: Thomas W. Plummer of Queens College & NYCEP; Briana L. Pobiner of the National Museum of Natural History, Smithsonian Institution; James S. Oliver of Illinois State Museum and Liverpool John Moores University; Laura C. Bishop of Liverpool John Moores University; David R. Braun of George Washington University; Peter W. Ditchfield of University of Oxford; John W. Seaman III , Katie M. Binetti and John W. Seaman Jr. of Baylor University; Fritz Hertel of California State University and Richard Potts of the National Museum of Natural History, Smithsonian Institution and National Museums of Kenya.
The research was supported by funding from the National Science Foundation, Leakey Foundation, Wenner-Gren Foundation, National Geographic Society, The Leverhulme Trust, University of California, Baylor University and the City University of New York. Additional logistical support was provided by the Smithsonian Institution's Human Origins Program and the Peter Buck Fund for Human Origins Research, the British Institute of Eastern Africa and the National Museums of Kenya.
http://www.sciencedaily.com/releases/2013/05/130510124441.htm
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| Posted 13-05-2013 at 19:39
Earliest Archaeological Evidence of Sustained Carnivory by Human Ancestors
Located on the southern shores of the Winam Gulf of Lake Victoria in southwestern Kenya, the Kanjera South archaeological site has now yielded finds that, according to a recent study published May 1, 2013 in the open-access scientific journal PLOS ONE, provide strong material evidence that hominins (early human ancestors) practiced "persistent carnivory", or acquired, transported, processed and presumably consumed animals on a regular basis, about 2 million years ago. The finding helps to address the dearth of available data or evidence that would bridge the gap between 2.6 mya, when the earliest stone tools are thought to have emerged, and 1.8 mya, the date after which the faunal evidence becomes more plentiful.
The team of scientists studied three large, well-preserved, and stratified ancient faunal assemblages (a collection of associated animal remains) that date to ~2.0 Ma, assemblages that formed on an ancient grassy plain located between a freshwater lake and wooded slopes of nearby hills and mountains on the Homa peninsula, a landmass distinguished by the Homa volcano. In three select excavations of 1m ×1m squares, they recovered several thousand well-preserved faunal specimens using lightweight hammers and awls. The faunal remains consisted of fossilized bone remnants of numerous small bovids [cloven-hoofed, ruminant mammals such as gazelles] and a smaller number of medium-sized bovids. What they found was clear evidence of "bone modification", meaning fossil bones bearing cut marks and/or hammerstone percussion damage made presumably by tool-bearing hominins. All remains were located within a stratified sequence of 3 separate archaeofaunal-bearing deposits, or beds, labeled KS (Kanjera South)-1 through KS-3. Report the researchers, "These specimens provide unambiguous evidence of hominin processing of bovid remains, and indicate a functional relationship between artifactual and faunal materials".[1]http://popular-archaeology.com/issue/march-2013/article/earliest-archaeological-evidence-of-sustained-carnivory-by-human-ancestors
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| Posted 13-05-2013 at 19:47
Archaeologists Reopen Investigation of Early Humans at Manot Cave in Israel
Situated in the western Galilee region of present-day Israel, Manot Cave lies about 10 km north of the Hayonim Cave site and 50 km northeast of the well-known Mt. Carmel cave sites. Although less-known than the well-publicized prehistoric "sister" sites of Qafzeh and Kebara, the cave has recently yielded evidence of human occupation dated back to at least Upper Paleolithic times, when early modern humans and Neanderthals are suggested to have coexisted around the Mediterranean and further north into present-day Europe. Adding to evidence uncovered at other similar locations, scientists hope that the finds of the cave will help elucidate the story of early modern human and Neanderthal existence in the Levant, and perhaps even help answer questions related to one possible stage in the spread of modern humans from Africa to Europe.
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Location of Manot Cave and other prehistoric caves in northern Israel. Courtesy Israel Antiquities Authority
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Now, a team of archaeologists from the Israel Antiquities Authority, along with students and volunteers, will return to the cave site during the summer of 2013 and reopen an investigation that began first with a 2008 survey and 2010 excavation that turned up some promising signs. The finds are particularly significant in light of the fact that the cave was blocked by natural rockfall about 15,000 years ago, sealing it from further disturbance by any subsequent natural or human elements.
It was first discovered during construction activity in 2008 that damaged the roof of the cave. A research team from the Cave Research Unit of Hebrew University of Jerusalem was quickly called in to survey the site. In that survey, they recovered a human skull, later determined to be that of an anatomically modern human, and other archaeological remains that were reported to the Israel Antiquities Authority (IAA) for further exploration. The IAA subsequently conducted another survey in 2008 and then a full-scale excavation in 2010.
In addition to the human skull remains, the investigations have thus far revealed Middle and Upper Paleolithic (250,000–15,000 BP ) lithic artifacts, charcoal remains and an abundance of faunal remains, including animal bones. Reports the IAA investigators: "Notable among the lithic components were Middle and Upper Palaeolithic tools and cores. The tools consisted of a Levallois point, typical of the Mousterian [commonly attributed to Neanderthals] culture. The Upper Paleolithic component included burins, bladelets, overpassed blades. Notable are Aurignacian tools, such as nosed and carinated endscrapers." Also found was a polished bone pendant. [1]
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A Mousterian point (Middle Palaeolithic) and a carnivore canine from the 2008 survey. Courtesy Israel Antiquities Authority
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Upper Palaeolithic finds from the 2008 survey. Courtesy Israel Antiquities Authority
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Animal remains included that of large mammals, such as horse, mountain gazelle, fallow deer, red deer, bear, aurochs, and hyena, as well as microfauna. Additional human bones turned up, as well.
"The fieldwork at Manot shows great research potential", reports the IAA. "The archaeological finds recovered so far attest to a cave inhabited from the Middle Paleolithic through the Epipalaeolithic periods (250,000–15,000 BP), when it was naturally blocked. The characteristics and composition of chipped stone tools, animal bones and bone tools suggest that occupation in the cave was intensive during the Upper Palaeolithic period." [1]
Speleothems (secondary mineral deposits formed in the cave), which predate human occupation, were found in abundance throughout the cave. Scientists will use speleothem samples to date the human occupations using U-Th dating and isotopic analysis, which will also be helpful in reconstructing the paleoclimate in which the cave existed.
"In sum", concludes the IAA reporters, "the excavation project at Manot is expected to shed light on one of the most important phases in the history of mankind, the surrounding faunal world and the climate and environment men had to cope with in the Eastern Mediterranean region." [1]
More about the Manot Cave excavations can be found at the Manot Cave Preliminary Report page, and information about how one can participate is located at the Findadig website of the Biblical Archaeology Society.
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[1] Manot Cave Preliminary Report, Israel Journal 124, Hadashot Arkheologiyot, Excavations and Surveys in Israel. http://www.hadashot-esi.org.il/report_detail_eng.asp?id=2183&mag_id=119
Cover Photo, Top Left: Speleothems inside Manot Cave. Courtesy Israel Antiquities Authority
http://popular-archaeology.com/issue/march-2013/article/archaeologists-reopen-investigation-of-early-humans-at-manot-cave-in-israel
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| Posted 13-05-2013 at 21:09
New hominin site found in China
A joint team from Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Chinese Academy of Sciences, Institute of Cultural Relics and Archaeology, and Office for Cultural Relics Administration of Daoxian County, unearthed five hominin teeth and a large number of mammalian fossils from the Fuyan Cave site in Daoxian County, Hunan Province of China during an excavation carried out in September and October, 2011.
Researchers announced their finding in the latest issue of Acta Anthropologica Sinica 2013, providing new data for the study of human evolution and adaptive behaviour in South China.
Fuyan Cave site, also called Houbeishan cave by local farmers, was initially discovered in 1984.
Teeth similar to Homo sapiens
This excavation was carried out in two trenches in an area of total 20m2. Five hominin teeth and large number of mammalian fossils were unearthed. The general morphological characteristics of the five hominin teeth is quite similar to those of Homo sapiens, and the size of these teeth all falls into the tooth size variation of Chinese modern humans. Thirty nine mammalian species, including some undetermined species, have been recognized, and only a few of them are extinct, e.g. Ailuropoda baconi, Crocuta ultima, Stegodon orientalis, Megatapirus augustus and Sus cf. australis.
Occupation in Late Pleistocene
Preliminary U-series dating shows that the sediments were formed after 141700±12100 years, and the general feature of the mammalian fauna suggests a late Late Pleistocene age. Therefore, researchers inferred that hominin probably occupied the cave in the Late Pleistocene.
“Our excavation shows the cave has great potential perspectives. Further excavation and laboratory study of cave development, filling sequence, hominin teeth morphology, dating, and environmental change from the Fuyan Cave as well as some adjacent caves will help better understand the human evolution and adaptive behaviour in Southwest Hunan, east Guangxi, and north Guangdong”, said corresponding author Dr. PEI Shuwen of the IVPP.
Source: Institute of Vertebrate Paleontology and Paleoanthropology (IVPP)
http://www.pasthorizonspr.com/index.php/archives/05/2013/new-hominin-site-found-in-china
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| Posted 14-05-2013 at 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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| Posted 14-05-2013 at 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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| Posted 14-05-2013 at 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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| Posted 14-05-2013 at 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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| Posted 14-05-2013 at 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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| Posted 14-05-2013 at 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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| Posted 14-05-2013 at 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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coldrum
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| Posted 15-05-2013 at 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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