Mostrando entradas con la etiqueta Sciencedaily. Mostrar todas las entradas
Decoding the Genetic History of the Texas Longhorn
The study of the genome of the Longhorn and related breeds tells a fascinating global history of human and cattle migration. It traces back through Christopher Columbus' second voyage to the New World, the Moorish invasion of Spain and the ancient domestication of the aurochs in the Middle East and India.
"It's a real Texas story, an American story," said Emily Jane McTavish, a doctoral student in the lab of biology professor David Hillis. "For a long time people thought these New World cattle were domesticated from a pure European lineage. But it turns out they have a more complex, more hybrid, more global ancestry, and there's evidence that this genetic diversity is partially responsible for their greater resilience to harsh climatic conditions."
To reconstruct the genetic history of Texas Longhorns, McTavish, Hillis and colleagues from the University of Missouri-Columbia analyzed almost 50,000 genetic markers from 58 cattle breeds. The most comprehensive such analysis to date, it was funded in part by the Cattlemen's Texas Longhorn Conservancy, which helped the scientists get access to samples used by ranchers.
Among the findings was that the Texas Longhorn breed are direct descendants of the first cattle in the New World. The ancestral cattle were brought over by Columbus in 1493 to the island of Hispaniola. They traveled the rest of the way to the continent in 1521 on the ships of later Spanish colonists.
Over the next two centuries the Spanish moved the cattle north, arriving in the area that would become Texas near the end of the 17th century. The cattle escaped or were turned loose on the open range, where they remained mostly wild for the next two centuries
"It was known on some level that Longhorns are descendants from cattle brought over by early Spanish settlers," said Hillis, the Alfred W. Roark Centennial Professor in the College of Natural Sciences, "but they look so different from the cattle you see in Spain and Portugal today. So there was speculation that there had been interbreeding with later imports from Europe. But their genetic signature is co mpletely consistent with being direct descendants of the cattle Columbus brought over."
The study reveals that being a "pure" descendant of cattle from the Iberian peninsula indicates a more complicated ancestry than was understood. Approximately 85 percent of the Longhorn genome is "taurine," descended from the ancient domestication of the wild aurochs that occurred in the Middle East 8,000-10,000 years ago. As a result, Longhorns look similar to purer taurine breeds such as Holstein, Hereford and Angus, which came to Europe from the Middle East.
The other 15 percent of the genome is "indicine," from the other ancient domestication of the aurochs, in India. These indicine cattle, which often have a characteristic hump at the back of the neck, spread into Africa and from there up to the Iberian peninsula
"It's consistent with the Moorish invasions from the 8th to the 13th centuries," said Hillis. "The Moors brought cattle with them, and brought these African genes, and of course the European cattle were there as well. All those influences come together in the cattle of the Iberian peninsula, which were used to stock the Canary Islands, which is where Columbus stopped and picked up cattle on his second voyage and brought them to the New World."
Once in the New World, most of the cattle eventually went feral. Under the pressures of natural selection they were able to re-evolve ancient survival traits that had been artificially bred out of their European ancestors. Selection for longer horns allowed them to defend against wild predators. They became leaner and more able to survive heat and drought.
"The Longhorns that were in the area when Anglo settlers arrived almost looked more like the ancestral aurochsen than like modern cattle breeds," said McTavish. "Living wild on the range, they had to become very self sufficient. Having that genetic reservoir from those wild ancestors made it possible for a lot of those traits to be selected for once again."
McTavish said it's possible the indicine heritage in particular helped, because the climate in India and Africa tended to be hotter and drier than in Europe.
The Longhorns remained wild on the range, or very loosely managed, until after the Civil War, when Texans rounded up the wild herds and began supplying beef to the rest of the country. Since then the fortunes of the Longhorns have waxed and waned depending on how their unique genetic profile intersects with the changing needs of American consumers.
"The Longhorns almost went extinct starting in the late 19th century," said Hillis. "A lot of the value of cattle at that time had to do with the fat they had, because the primary lighting source people had was candles, made of tallow, and Texas Longhorns have very low fat content. Ranchers began fencing off the range and importing breeds from Europe that had higher fat content. That's when Americans began developing their taste for fatty beef, so then the other cattle became valuable in that respect as well. The only reason the Longhorns didn't go extinct was because half a dozen or so ranchers kept herds going even though they knew that these other breeds were more valuable in some sense. They appreciated that the Longhorns were hardier, more self-sufficient."
Hillis, who raises Longhorns of his own out at the Double Helix Ranch, said that the winds of history now seem to be blowing in the Longhorns' direction. They can survive in hotter, drier climates, which will become increasingly important as the world warms. They provide lean and grass-fed beef, which is seen as healthier by many consumers. And their genes may prove valuable to ranchers, who can use the increasingly sophisticated genetic information to selectively breed the Longhorns' toughness into other breeds of cattle.
"It's another chapter in the story of a breed that is part of the history of Texas," he said.
Estudio de pinturas rupestres sugiere que los Neandertal eran más inteligentes de lo que pensábamos
En la antigüedad, vivieron varias especies de humanos, y varias de ellas convivieron al mismo tiempo. Sin embargo, por alguna razón se extinguieron las demás y el Homo Sapiens sobrevivió.
La expresión en pinturas rupestres es vista como el reflejo de un pensamiento simbólico sofisticado, que implica expresar con imágenes pensamientos y sucesos, con la idea de mostrarlos. También implica el desarrollo de técnica. Hasta el momento, se asociaba este desarrollo sólo al Homo Sapiens.
Una investigación publicada en Science por João Zilhão y Alistair Pike, de la Universidad de Bristol, midió las edades de 50 pinturas en 11 cavernas españolas. Según sus cálculos, algunas de las imágenes tienen al menos 41.000 años – probablemente más. Los primeros humanos modernos llegaron a Europa hace 40.000 años.
Los métodos tradicionales para calcular la edad de las pinturas rupestres son poco exactos, con errores de miles de años. Zilhão y Pike estudiaron los depósitos minerales formados sobre la superficie de las cuevas y las pinturas, en lugar de usar mediciones de carbono. Mientras mayor era el depósito, más antigua era la pintura.
Las posibilidades que despierta este descubrimiento implicarían que, o bien los Homo Sapiens llegaron a Europa con una tradición de hacer dibujos – algo de lo que no hay ninguna evidencia -; o bien aprendieron rápidamente a pintar apenas llegaron a Europa. Esta última teoría lleva a preguntarse por qué habría ocurrido tan repentinamente ese cambio cultural, en ese lugar en específico.
La tercera posibilidad es que los artistas no fueran Homo Sapiens, sino que Neandertales. Esto es sólo una hipótesis que debe ser investigada, pero mostraría que en realidad los Neandertal, considerados tradicionalmente como menos inteligentes, eran en realidad pensadores sofisticados, capaces de simbolismo, planificación social y empatía.
Las pinturas serían una evidencia que permitiría eliminar la imagen de retrasado que tradicionalmente ha cargado el Neandertal.
Fossil Discovery: More Evidence for Asia, Not Africa, as the Source of Earliest Anthropoid Primates
An international team of researchers has announced the discovery of Afrasia djijidae, a new fossil primate from Myanmar that illuminates a critical step in the evolution of early anthropoids -- the group that includes humans, apes, and monkeys. The 37-million-year-old Afrasia closely resembles another early anthropoid, Afrotarsius libycus, recently discovered at a site of similar age in the Sahara Desert of Libya. The close similarity between Afrasia and Afrotarsius indicates that early anthropoids colonized Africa only shortly before the time when these animals lived. The colonization of Africa by early anthropoids was a pivotal step in primate and human evolution, because it set the stage for the later evolution of more advanced apes and humans there.
The scientific paper describing the discovery appears June 4 inProceedings of the National Academy of Sciences.
For decades, scientists thought that anthropoid evolution was rooted in Africa. However, more recent fossil discoveries in China, Myanmar, and other Asian countries have rapidly altered scientific opinion about where this group of distant human ancestors first evolved. Afrasia is the latest in a series of fossil discoveries that are overturning the concept of Africa as the starting point for anthropoid primate evolution.
"Not only does Afrasia help seal the case that anthropoids first evolved in Asia, it also tells us when our anthropoid ancestors first made their way to Africa, where they continued to evolve into apes and humans," says Chris Beard, Carnegie Museum of Natural History paleontologist and member of the discovery team that also included researchers from Myanmar, Thailand, and France. Beard is renowned for his extensive work on primate evolution and anthropoid origins. "Afrasia is a game-changer because for the first time it signals when our distant ancestors initially colonized Africa. If this ancient migration had never taken place, we wouldn't be here talking about it."
Timing is everything
Paleontologists have been divided over exactly how and when early Asian anthropoids made their way from Asia to Africa. The trip could not have been easy, because a more extensive version of the modern Mediterranean Sea called the Tethys Sea separated Africa from Eurasia at that time. While the discovery of Afrasia does not solve the exact route early anthropoids followed in reaching Africa, it does suggest that the colonization event occurred relatively recently, only shortly before the first anthropoid fossils are found in the African fossil record.
Myanmar's 37-million-year-old Afrasia is remarkable in that its teeth closely resemble those of Afrotarsius libycus, a North African primate dating to about the same time. The four known teeth of Afrasia were recovered after six years of sifting through tons of sediment near Nyaungpinle in central Myanmar. This locality occurs in the middle Eocene Pondaung Formation, where the same international research team discovered Ganlea megacanina, an influential fossil described in 2009 that helped solidify the presence of early anthropoid primates in Asia.
Details of tooth shape in the Asian Afrasia and the North African Afrotarsius fossils indicate that these animals probably ate insects. The size of their teeth suggests that in life these animals weighed around 3.5 ounces (100 g), roughly the size of a modern tarsier.
Because of the complicated structure of mammalian teeth, paleontologists often use them as fingerprints to reconstruct how extinct species are related to each other and their modern relatives. These similarities provide strong evidence that Afrasia's Asian cousins colonized North Africa only shortly before the appearance of Afrotarsius in the African fossil record. If Asian anthropoids had arrived in North Africa earlier, there would have been time for more differences to evolve between Afrasia and Afrotarsius. The close similarity in age and anatomy shared by the two species makes Afrasia a touchstone in the quest to date the spread of anthropoid primates from Asia to Africa.
"For years we thought the African fossil record was simply bad," says Professor Jean-Jacques Jaeger of the University of Poitiers in France, the team leader and a Carnegie Museum research associate. "The fact that such similar anthropoids lived at the same time in Myanmar and Libya suggests that the gap in early African anthropoid evolution is actually real. Anthropoids didn't arrive in Africa until right before we find their fossils in Libya."
Implications for future research
The search for the origin of early anthropoids -- and, by extension, early human ancestors -- is a focal point of modern paleoanthropology. The discovery of Afrasia shows that one lineage of early anthropoids colonized Africa around 37-38 million years ago, but the diversity of early anthropoids known from the Libyan site that produced Afrotarsius libycus hints that the true picture was more complicated. These other Libyan fossil anthropoids may be the descendants of one or more additional Asian colonists, because they don't appear to be specially related to Afrasia and Afrotarsius. Fossil evidence of evolutionary divergence -- when a species divides to create new lineages -- is critical data for researchers in evolution. The groundbreaking discovery of the relationship between Asia's Afrasia and North Africa's Afrotarsius is an important benchmark for pinpointing the date at which Asian anthropoids colonized Africa.
"Groundbreaking research like this underscores the vitality of modern natural history museums," says Sam Taylor, director of Carnegie Museum of Natural History. "Research like this can only be sustained by the irreplaceable collections, curatorial expertise, and scientific infrastructure that natural history museums provide. At the same time, cutting-edge science like this revitalizes our museum's educational programs and propels its mission."
"Reconstructing events like the colonization of Africa by early anthropoids is a lot like solving a very cold case file," says Beard. "Afrasia may not be the anthropoid who actually committed the act, but it is definitely on our short list of prime suspects."
Tag :
Sciencedaily
Handsome By Chance: Why Humans Look Different From Neanderthals
Chance, not natural selection, best explains why the modern human skull looks so different from that of its Neanderthal relative, according to a new study led by Tim Weaver, assistant professor of anthropology at UC Davis.
"For 150 years, scientists have tried to decipher why Neanderthal skulls are different from those of modern humans," Weaver said. "Most accounts have emphasized natural selection and the possible adaptive value of either Neanderthal or modern human traits. We show that instead, random changes over the past 500,000 years or so – since Neanderthals and modern humans became isolated from each other – are the best explanation for these differences."
Weaver and his colleagues compared cranial measurements of 2,524 modern human skulls and 20 Neanderthal specimens, then contrasted those results with genetic information from a separate sample of 1,056 modern humans.
The scientists concluded that Neanderthals did not develop their protruding mid-faces as an adaptation to icy Pleistocene weather or the demands of using teeth as tools, and the retracted faces of modern humans are not an adaptation for language, as some anthropologists have proposed.
Instead, random "genetic drift" is the likeliest reason for these skull differences.
Weaver conducted the research with Charles Roseman, an anthropologist at the University of Illinois at Urbana-Champaign, and Chris Stringer, a paleoanthropologist at the Natural History Museum in London.
Evolution of Birds Is Result of a Drastic Change in How Dinosaurs Developed
Researchers from Harvard University, The University of Texas at Austin and elsewhere have found evidence that the evolution of birds is the result of a drastic change in how dinosaurs developed. Scientists have long understood that modern birds descended from dinosaurs. Rather than take years to reach sexual maturity, as many dinosaurs did, birds sped up the clock -- some species take as little as 12 weeks to mature -- allowing them to retain the physical characteristics of baby dinosaurs.
The results of the study appeared May 27 in an online edition of the journal Nature.
"What is interesting about this research is the way it illustrates evolution as a developmental phenomenon," said Arkhat Abzhanov, associate professor at Harvard and study co-author. "By changing the developmental biology in early species, nature has produced the modern bird -- an entirely new creature -- and one that, with approximately 10,000 species, is today the most successful group of land vertebrates on the planet."
While it's clear simply from looking at the skulls of dinosaurs and modern birds that the two creatures are vastly different -- dinosaurs have distinctively long snouts and mouths bristling with teeth, while birds have proportionally larger eyes and brains -- it was the realization that skulls of modern birds and juvenile dinosaurs show a surprising degree of similarity that sparked the study.
"No one had told the big story of the evolution of the bird head before," said Bhart-Anjan Bhullar, a Harvard PhD student and first author of the study. "There had been a number of smaller studies that focused on particular points of the anatomy, but no one had looked at the entire picture. What's interesting is that when you do that, you see the origins of the features that make the bird head special lie deep in the history of the evolution of Archosaurs, a group of animals that were the dominant, meat-eating animals for millions of years."
To tackle the problem, the researchers turned to an unusual methodology. Using CT scanners at Harvard and The University of Texas at Austin, they scanned dozens of skulls, ranging from modern birds to theropods -- the dinosaurs most closely related to birds -- to early dinosaur species. By marking various "landmarks" -- such as the orbits, cranial cavity and other bones in the skull -- on each scan, researchers were able to track how the skull changed shape over millions of years.
Tim Rowe is a director of The University of Texas High-Resolution X-Ray Scanning Facility, where some of the scans were performed, and study co-author.
"We examined skulls from the entire lineage that gave rise to modern birds," Abzhanov said. "We looked back approximately 250 million years, to the Archosaurs, the group which gave rise to crocodiles and alligators as well as modern birds. Our goal was to look at these skulls to see how they changed, and try to understand what actually happened during the evolution of the bird skull."
What the researchers found was surprising -- while early dinosaurs, even those closely related to modern birds, undergo vast morphological changes as they mature, the skulls of juvenile and adult birds remain remarkably similar.
In the case of modern birds, Abzhanov said, the change is the result of a process known as progenesis, which causes an animal to reach sexual maturity earlier. Unlike their dinosaurian ancestors, modern birds take dramatically less time -- just 12 weeks in some species -- to reach maturity, allowing birds to retain the characteristics of their juvenile ancestors into adulthood.
Ultimately, Abzhanov said, the way the bird skull evolved -- through changes in the developmental timeline -- highlights the diversity of evolutionary strategies that have been used over millions of years.
"That you can have such dramatic success simply by changing the relative timing of events in a creature's development is remarkable," he said. "We now understand the relationship between birds and dinosaurs that much better, and we can say that, when we look at birds, we are actually looking at juvenile dinosaurs."
"It shows that there's so much for evolution to act upon," Bhullar agreed. "When we think of an organism, especially a complex organism, we often think of it as a static entity, but to really study something you have to look at its whole existence, and understand that one portion of its life can be parceled out and made into the entire lifespan of a new, and in this case, radically successful organism."
Tag :
Birds,
Sciencedaily
Inequality Dates Back to Stone Age: Earliest Evidence Yet of Differential Access to Land
Hereditary inequality began over 7,000 years ago in the early Neolithic era, with new evidence showing that farmers buried with tools had access to better land than those buried without.
The research, carried out by archaeologists from the Universities of Bristol, Cardiff and Oxford, is published in the Proceedings of the National Academy of Sciences (PNAS), May 28.
By studying more than 300 human skeletons from sites across central Europe, Professor Alex Bentley and an international team of colleagues funded by the Arts and Humanities Research Council uncovered evidence of differential land access among the first Neolithic farmers -- the earliest such evidence yet found.
Strontium isotope analysis of the skeletons, which provides indications of place of origin, indicated that men buried with distinctive Neolithic stone adzes (tools used for smoothing or carving wood) had less variable isotope signatures than men buried without adzes. This suggests those buried with adzes had access to closer -- and probably better -- land than those buried without.
Professor Bentley, Professor of Archaeology and Anthropology at the University of Bristol, said: "The men buried with adzes appear to have lived on food grown in areas of loess, the fertile and productive soil favoured by early farmers. This indicates they had consistent access to preferred farming areas."
The strontium isotope analysis also revealed that early Neolithic women were more likely than men to have originated from areas outside those where their bodies were found. This is a strong indication of patrilocality, a male-centred kinship system where females move to reside in the location of the males when they marry.
This new evidence from the skeletons is consistent with other archaeological, genetic, anthropological and even linguistic evidence for patrilocality in Neolithic Europe. The results have implications for genetic modelling of how human populations expanded in the Neolithic, for which sex-biased mobility patterns and status differences are increasing seen as crucial.
Professor Bentley said: "Our results, along with archaeobotanical studies that indicate the earliest farmers of Neolithic Germany had a system of land tenure, suggest that the origins of differential access to land can be traced back to an early part of the Neolithic era, rather than only to later prehistory when inequality and intergenerational wealth transfers are more clearly evidenced in burials and material culture.
"It seems the Neolithic era introduced heritable property (land and livestock) into Europe and that wealth inequality got underway when this happened. After that, of course, there was no looking back: through the Bronze Age, Iron Age and Industrial era wealth inequality increased but the 'seeds' of inequality were sown way back in the Neolithic."
Tag :
Sciencedaily,
Stone age
16th-Century Korean Mummy Provides Clue to Hepatitis B Virus Genetic Code
The discovery of a mummified Korean child with relatively preserved organs enabled an Israeli-South Korean scientific team to conduct a genetic analysis on a liver biopsy which revealed a unique hepatitis B virus (HBV) genotype C2 sequence common in Southeast Asia.
Additional analysis of the ancient HBV genomes may be used as a model to study the evolution of chronic hepatitis B and help understand the spread of the virus, possibly from Africa to East-Asia. It also may shed further light on the migratory pathway of hepatitis B in the Far East from China and Japan to Korea as well as to other regions in Asia and Australia where it is a major cause of cirrhosis and liver cancer.
The reconstruction of the ancient hepatitis B virus genetic code is the oldest full viral genome described in the scientific literature to date. It was reported in the May 21 edition of the scientific journal Hepathology by a research team from the Hebrew University of Jerusalem's Koret School of Veterinary Medicine, the Robert H. Smith Faculty of Agriculture, Food and Environment; the Hebrew University's Faculty of Medicine, the Hadassah Medical Center's Liver Unit; Dankook University and Seoul National University in South Korea.
Carbon 14 tests of the clothing of the mummy suggests that the boy lived around the 16th century during the Korean Joseon Dynasty. The viral DNA sequences recovered from the liver biopsy enabled the scientists to map the entire ancient hepatitis B viral genome.
Using modern-day molecular genetic techniques, the researchers compared the ancient DNA sequences with contemporary viral genomes disclosing distinct differences. The changes in the genetic code are believed to result from spontaneous mutations and possibly environmental pressures during the virus evolutionary process. Based on the observed mutations rates over time, the analysis suggests that the reconstructed mummy's hepatitis B virus DNA had its origin between 3,000 to 100,000 years ago.
The hepatitis B virus is transmitted through the contact with infected body fluids , i.e. from carrier mothers to their babies, through sexual contact and intravenous drug abuse. According to the World Health Organization, there are over 400 million carriers of the virus worldwide, predominantly in Africa, China and South Korea, where up to 15 percent of the population are cariers of the virus. In recent years, universal immunization of newborns against hepatitis B in Israel and in South Korea has lead to a massive decline in the incidence of infection.
Tag :
Sciencedaily
It Took Earth Ten Million Years to Recover from Greatest Mass Extinction
It took some 10 million years for Earth to recover from the greatest mass extinction of all time, latest research has revealed.
Life was nearly wiped out 250 million years ago, with only 10 per cent of plants and animals surviving. It is currently much debated how life recovered from this cataclysm, whether quickly or slowly.
Recent evidence for a rapid bounce-back is evaluated in a new review article by Dr Zhong-Qiang Chen, from the China University of Geosciences in Wuhan, and Professor Michael Benton from the University of Bristol. They find that recovery from the crisis lasted some 10 million years, as explained May 27 in Nature Geoscience.
There were apparently two reasons for the delay, the sheer intensity of the crisis, and continuing grim conditions on Earth after the first wave of extinction.
The end-Permian crisis, by far the most dramatic biological crisis to affect life on Earth, was triggered by a number of physical environmental shocks -- global warming, acid rain, ocean acidification and ocean anoxia. These were enough to kill off 90 per cent of living things on land and in the sea.
Dr Chen said: "It is hard to imagine how so much of life could have been killed, but there is no doubt from some of the fantastic rock sections in China and elsewhere round the world that this was the biggest crisis ever faced by life."
Current research shows that the grim conditions continued in bursts for some five to six million years after the initial crisis, with repeated carbon and oxygen crises, warming and other ill effects.
Some groups of animals on the sea and land did recover quickly and began to rebuild their ecosystems, but they suffered further setbacks. Life had not really recovered in these early phases because permanent ecosystems were not established.
Professor Benton, Professor of Vertebrate Palaeontology at the University of Bristol, said: "Life seemed to be getting back to normal when another crisis hit and set it back again. The carbon crises were repeated many times, and then finally conditions became normal again after five million years or so."
Finally, after the environmental crises ceased to be so severe, more complex ecosystems emerged. In the sea, new groups, such as ancestral crabs and lobsters, as well as the first marine reptiles, came on the scene, and they formed the basis of future modern-style ecosystems.
Professor Benton added: "We often see mass extinctions as entirely negative but in this most devastating case, life did recover, after many millions of years, and new groups emerged. The event had re-set evolution. However, the causes of the killing -- global warming, acid rain, ocean acidification -- sound eerily familiar to us today. Perhaps we can learn something from these ancient events."
Archaeology: Spectacular Tomb Containing More Than 80 Individuals Discovered in Peru
A team of archaeologists from the Université libre de Bruxelles (ULB)
has discovered a spectacular tomb containing more than eighty
individuals of different ages. This discovery -- provisionally dated to
around 1000 years ago -- was made at the site of Pachacamac, which is
currently under review for UNESCO World Heritage status.
Pachacamac, situated on the Pacific coast about thirty kilometres
from Lima, is one of the largest Prehispanic sites in South America.
Professor Peter Eeckhout -- under the auspices of the ULB -- has been
carrying out fieldwork at the site for the past 20 years. The 2012
season resulted in some particularly remarkable discoveries.
The Ychsma Project team undertook to record and excavate a series of
Inca storage facilities (15th-16th c. AD), as well as a more ancient
cemetery which had been detected during exploratory work in 2004.
It was here -- directly in front of the Temple of Pachacamac -- that
the most important discovery was made. A scatter of later period burials
was found to conceal an enormous burial chamber 20 metres long ;
miraculously, it had survived the pillaging of the colonial period --
which was particularly intensive on this site -- and was completely
intact.
The tomb is oval in outline, excavated into the earth and covered
with a roof of reeds supported by carved and shaped tree trunks. A dozen
newborn babies and infants were distributed around the perimeter, their
heads oriented towards the tomb. The main chamber was seperated into
two sections, separated by a wall of mud bricks which served as a base
for yet more burials.
Inside the chambers, the archaeologists uncovered the remains of more
than 70 skeletons and mummies (many of which still retained their
wrappings), all in the characteristic fœtal position. The burials
represented both sexes and all ages, and were often accompanied by
offrenda including ceramic vessels, animals (dogs, guinea pigs), copper
and gold alloy artefacts, masks (or 'false heads') in painted wood,
calabashes, etc. These items are currently under restoration and
analysis. Babies and very young infants were particularly common.
The team's group of physical anthropologists, under the direction of
Dr Lawrence Owens (University of London), have posited the possibility
of a genetic relationship between many of the individuals, on the basis
of certain morphological traits recorded in the skeletons. Certain of
the individuals suffered mortal injuries, physical trauma or serious
illness.
Previous work by the Ychsma Project has revealed the extensive
presence of disease in the Pachacamac skeletal population, leading to
the suggestion that the affected individuals had, as testified by Inca
sources, travelled to the site in search of a cure: a form of
Prehispanic Lourdes.
Professor Eeckhout and his colleagues are currently carrying out
laboratory analyses aimed at answering numerous questions that have
arisen concerning this discovery, and how to contextualise it within the
wider context of the site and the period(s) in question. Were the
infants sacrificed ? Were the bodies all interred at the same time as a
form of communal burial, or was the chamber reused over longer periods
of time like some sort of crypt? Did the individuals come from
Pachacamac or further afield? Did they belong to the same family or
larger kinship group ? What was their cause of death…?
The artefacts found in the tomb date it stylistically to around 1000 AD, although this is yet to be confirmed radiometrically.
Tag :
Sciencedaily
Oldest Art Even Older: New Dates from Geißenklösterle Cave Show Early Arrival of Modern Humans, Art and Music
New dates from Geißenklösterle Cave in Southwest Germany document the early arrival of modern humans and early appearance of art and music.
Researchers from Oxford and Tübingen have published new radiocarbon dates from the from Geißenklösterle Cave in Swabian Jura of Southwestern Germany in theJournal of Human Evolution. The new dates use improved methods to remove contamination and produced ages between began between 42,000 – 43,000 years ago for start of the Aurignacian, the first culture to produce a wide range of figurative art, music and other key innovations as postulated in the Kulturpumpe Hypothesis. The full spectrum of these innovations were established in the region no later than 40 000 years ago.
These are the earliest radiocarbon dates of Aurignacian deposits, and they predate Aurignacian dates from Italy, France, England and other regions. These results are consistent with the Danube Corridor hypothesis postulating that modern humans migrated to Europe and rapidly moved up the Danube drainage. Geißenklösterle Cave is one of several caves in the Swabian Jura that have produced important examples of personal ornaments, figurative art, mythical imagery and musical instruments. The new dates from Geißenklösterle together with existing dates using thermoluminescence confirm the great antiquity of the Swabian Aurignacian.
The new dates indicate that modern humans entered the Upper Danube region prior to an extremely cold climatic phase referred to as the H4 event dating to ca. 40 000 years ago. Previously, researchers had argued that modern humans initially migrated up the Danube immediately following the H4 event. As it now looks modern humans entered southwestern Germany during a mild phase of the last Ice Age, under climactic conditions, which should have been inhabitable by indigenous populations of Neanderthals. Despite a major effort to identify archaeological signatures of interaction between Neanderthals and modern humans, researchers have yet to identify indications of cultural contact between these groups in Upper Danube region.
These results point to the Upper Danube Valley as a plausible homeland for the Aurignacian, with the Swabian caves producing the earliest record of technological and artistic innovations that are characteristic of the this period. Whether the many innovations best documented in Swabia were stimulated by climatic stress, competition between modern humans and Neanderthals or by other social-cultural dynamics remains a central focus of research by the archaeologists from Tübingen and Oxford. High-resolution dating of the kind reported here is essential for establishing a reliable the chronology for testing hypothesis to explain the expansion of modern humans into Europe, the processes that led to a wide range of cultural innovations including the advent of figurative art and music, and the extinction of Neanderthals.
Tag :
Sciencedaily
Human-Like Spine Morphology Found in Aquatic Eel Fossil
For decades, scientists believed that a spine with multiple segments was an exclusive feature of land-dwelling animals. But the discovery of the same anatomical feature in a 345-million-year-old eel suggests that this complex anatomy arose separately from -- and perhaps before -- the first species to walk on land.
Tarrasius problematicus was an eel-like fish that lived in shallow bodies of water in what is now Scotland, in the Carboniferous period between 359 million and 318 million years ago. Like many fish, Tarrasius was thought to have a vertebral column divided simply into body and tail segments. But in a new description of Tarrasius published inProceedings of the Royal Society B, Lauren Sallan describes a five-segment column much more similar to the spinal anatomy of land-dwelling animals called tetrapods, including humans.
The surprising find argues against a common assumption paleontologists use to determine from fossils whether an ancient species lived on land or in water.
"It's the last trait to fall," said Sallan, a graduate student in the Program in Integrative Biology at the University of Chicago Biological Sciences. "First, limbs were thought to show that a species was on land and walking, and now the vertebral morphology doesn't mean that they're on land either. So a lot of the things we associate with tetrapods actually arose first in fishes, and this is another example of that."
Tetrapods, which include the first species to walk on land as well as all modern mammals, reptiles, birds and humans, possess vertebrae organized into five distinct segments. From head to tail, the spinal vertebrae can be categorized into cervical, thoracic, lumbar, sacral and caudal sections, each with its own characteristic anatomy.
By contrast, fish vertebrae are typically categorized anatomically into two segments: caudal and pre-caudal. But the spinal column of Tarrasius shows a complexity more like that seen in tetrapods, with five segments separated by abrupt transitions.
"The morphology is just completely different in each series of vertebrae," Sallan said. "Like a tetrapod, you can tell which segment you're looking at from the basic morphology."
When Sallan began her research on Tarrasius, she wasn't looking for an unusual spine, but rather how the species fit evolutionarily among other early ray-finned fishes. While examining undescribed fossils at the National Museums Scotland in Edinburgh, Sallan found some unexpected features. Instead of the flexible notochord characteristic of most ancient fish species, Tarrasius possessed heavy vertebral bones organized into five anatomically distinct sections.
Armed with this new anatomical information, Sallan re-examined many other fossils of the species and detected evidence for spinal complexity that researchers previously had missed.
"This was in a different museum from where most of the specimens are, and previous workers had just been looking at the same fossils over and over," Sallan said. "It's basically an issue of finding what you expect to be there instead of what's actually there."
The appearance of tetrapod-like spinal organization in a ray-finned fish shatters the presumed relationship between complex vertebral anatomy and both walking and terrestriality. The eel-like Tarrasius possessed no hind fins and a long dorsal fin, indicating it used its surprisingly intricate spinal column for swimming, not walking. And while Tarrasius lived several million years after the first tetrapods with hands and feet, the discovery of these spinal features in a fish species confirms that this anatomy can evolve separate from the evolution of walking behavior.
"You can't use this trait to say that something was definitely on land or to identify a tetrapod, which is the way it is used in the field now," Sallan said.
Instead, the commonalities suggest that similar environments or other selective pressures may produce convergent evolution of this complex spinal organization. It also questions whether tetrapod-like expression of a family of factors responsible for body patterning -- the Hox genes -- is ancestral for both vertebrates and fishes, or truly essential for the development of these spinal segments. Since most knowledge about the relationship between Hox genes and body pattern development is based on genetic studies of modern tetrapods, the new finding emphasizes the need for more testing in fish species.
"Part of the problem is that the Hox expression data is available only for a few model organisms," Sallan said. "What's really needed is some expression data from other ray-finned fishes and tetrapods, things that are not mouse and chick and zebrafish. We need to try to get the full diversity of Hoxexpression."
It's also unclear how Tarrasius used its unexpectedly intricate spinal column in its daily life. Sallan speculates that the bony vertebrae may have been useful in propelling the fish's body during fast swimming, similar to the stiff vertebrae of modern marlins.
"I think it must help with stiffening the body, because the tail is so flexible," Sallan said. "If you look at the general shape, it's more like a tadpole or an early tetrapod, so it might just function to hold the body steady because the tail is flapping."
Tag :
Sciencedaily
Squid Ink from Jurassic Period Identical to Modern Cuttlefish Ink
The study is published online in the May 21 edition of the journal Proceedings of the National Academy of Sciences.
The finding -- in an extremely rare case of being able to study organic material that is hundreds of millions of years old -- suggests that the ink-screen escape mechanism of cephalopods -- cuttlefish, squid and octopuses -- has not evolved since the Jurassic period, and that melanin could be preserved intact in the fossils of a range of organisms.
"Though the other organic components of the cephalopod we studied are long gone, we've discovered through a variety of research methods that the melanin has remained in a condition that could be studied in exquisite detail," said John Simon, one of the study authors, a chemistry professor and the executive vice president and provost at U.Va.
One of the ink sacs studied is the only intact ink sac ever discovered.
Phillip Wilby of the British Geological Survey found it in Christian Malford, Wiltshire, England, west of London near Bristol. He sent samples to Simon and Japanese chemist Shoskue Ito, both experts on melanin, who then engaged research colleagues in the United States, the United Kingdom, Japan and India to investigate the samples using a combination of direct, high-resolution chemical techniques to determine whether or not the melanin had been preserved.
It had.
The investigators then compared the chemical composition of the fossil melanin to the melanin in the ink of the modern cuttlefish, Sepia officinalis, common to the Mediterranean, North and Baltic seas.
They found a match.
"It's close enough that I would argue that the pigmentation in this class of animals has not evolved in 160 million years," Simon said. "The whole machinery apparently has been locked in time and passed down through succeeding generations of cuttlefish. It's a very optimized system for this animal and has been optimized for a long time."
Generally animal tissue, made up mostly of protein, degrades quickly. Over the course of millions of years all that is likely to be found from an animal is skeletal remains or an impression of the shape of the animal in surrounding rock. Scientists can learn much about an animal by its bones and impressions, but without organic matter they are left with many unanswered questions.
But melanin is an exception. Though organic, it is highly resilient to degradation over the course of vast amounts of time.
"Out of all of the organic pigments in living systems, melanin has the highest odds of being found in the fossil record," Simon said. "That attribute also makes it a challenge to study. We had to use innovative methods from chemistry, biology and physics to isolate the melanin from the inorganic material."
The researchers cross-checked their work using separate complementary experiments designed to capitalize on various molecular features unique to melanin and determined the morphology and chemical composition of the material. This combination of in-depth, multidisciplinary techniques is not normally used by paleontologists to study fossil samples.
"I think the strength of this paper is that it is not tied to a single method," Simon said. "Any one technique would have brought some insights, but potentially more questions than insights. It was really the more holistic approach that fully characterized it and allowed us to actually do a real comparison between what existed during the Jurassic period and what exists now.
"It's also given us a handle on ways of identifying organic components in fossils that might have been missed using standard methods."
Tag :
Sciencedaily
Ancient Giant Turtle Fossil Was Size of Smart Car
Picture a turtle the size of a Smart car, with a shell large enough to double as a kiddie pool. Paleontologists from North Carolina State University have found just such a specimen -- the fossilized remains of a 60-million-year-old South American giant that lived in what is now Colombia.
The turtle in question is Carbonemys cofrinii, which means "coal turtle," and is part of a group of side-necked turtles known as pelomedusoides. The fossil was named Carbonemys because it was discovered in 2005 in a coal mine that was part of northern Colombia's Cerrejon formation. The specimen's skull measures 24 centimeters, roughly the size of a regulation NFL football. The shell which was recovered nearby -- and is believed to belong to the same species -- measures 172 centimeters, or about 5 feet 7 inches, long. That's the same height as Edwin Cadena, the NC State doctoral student who discovered the fossil.
"We had recovered smaller turtle specimens from the site. But after spending about four days working on uncovering the shell, I realized that this particular turtle was the biggest anyone had found in this area for this time period -- and it gave us the first evidence of giantism in freshwater turtles," Cadena says.
Smaller relatives of Carbonemys existed alongside dinosaurs. But the giant version appeared five million years after the dinosaurs vanished, during a period when giant varieties of many different reptiles -- including Titanoboa cerrejonensis, the largest snake ever discovered -- lived in this part of South America. Researchers believe that a combination of changes in the ecosystem, including fewer predators, a larger habitat area, plentiful food supply and climate changes, worked together to allow these giant species to survive. Carbonemys' habitat would have resembled a much warmer modern-day Orinoco or Amazon River delta.
In addition to the turtle's huge size, the fossil also shows that this particular turtle had massive, powerful jaws that would have enabled the omnivore to eat anything nearby -- from mollusks to smaller turtles or even crocodiles.
Thus far, only one specimen of this size has been recovered. Dr. Dan Ksepka, NC State paleontologist and research associate at the North Carolina Museum of Natural Sciences, believes that this is because a turtle of this size would need a large territory in order to obtain enough food to survive. "It's like having one big snapping turtle living in the middle of a lake," says Ksepka, co-author of the paper describing the find. "That turtle survives because it has eaten all of the major competitors for resources. We found many bite-marked shells at this site that show crocodilians preyed on side-necked turtles. None would have bothered an adult Carbonemys, though -- in fact smaller crocs would have been easy prey for this behemoth."
The paleontologists' findings appear in the Journal of Systematic Palaeontology. Dr. Carlos Jaramillo from the Smithsonian Tropical Research Institute in Panama and Dr. Jonathan Bloch from the Florida Museum of Natural History contributed to the work. The research was funded by grants from the Smithsonian Institute and the National Science Foundation.
Tag :
Sciencedaily
Ancient Sea Reptile With Gammy Jaw Suggests Dinosaurs Got Arthritis Too
Imagine having arthritis in your jaw bones ... if they're over 2 meters long! A new study by scientists at the University of Bristol has found signs of a degenerative condition similar to human arthritis in the jaw of a pliosaur, an ancient sea reptile that lived 150 million years ago. Such a disease has never been described before in fossilized Jurassic reptiles.
The Bristol scientists studied a giant specimen of the pliosaur Pliosaurusdating from the Upper Jurassic. Found in Westbury, Wiltshire, it has been kept since its discovery in the collections of the Bristol City Museum and Art Gallery.
The 8 metre long pliosaur was a terrifying creature with a large, crocodile-like head, a short neck, whale-like body and four powerful flippers to propel it through water in pursuit of prey.
With its huge jaws and 20 cm long teeth, it would have been capable of ripping most other marine reptiles or dinosaurs to pieces, but this particular individual was the unfortunate victim of an arthritis-like disease.
University of Bristol scientist, Dr Judyth Sassoon, was fascinated by the specimen when she saw it in the museum's collections and studied it for her MSc research project.
She soon noticed that it had the signs of a degenerative condition similar to human arthritis, that had eroded its left jaw joint, displacing the lower jaw to one side. This animal evidently lived with a crooked jaw for many years, because there are marks on the bone of the lower jaw where the teeth from the upper jaw impacted on the bone during feeding. Clearly the animal was still able to hunt in spite of its unfortunate condition.
There are several signs on the skeleton to suggest that the animal could have been an old female who had developed the condition as part of the aging process. The pliosaur's large size, and the fused skull bones, suggest maturity. It is identified, very tentatively, as possibly female because its skull crest is quite low -- presumed males had a higher crest.
Dr Judyth Sassoon said: "In the same way that aging humans develop arthritic hips, this old lady developed an arthritic jaw, and survived with her disability for some time. But an unhealed fracture on the jaw indicates that at some time the jaw weakened and eventually broke. With a broken jaw, the pliosaur would not have been able to feed and that final accident probably led to her demise."
Pliosaurs were probably pursuit or ambush predators, feeding on fish, squid and other marine reptiles but would also have been capable of scavenging. They were at the top of their food chains, so there would not have been any predators to take advantage of an aging, disabled pliosaur -- except for another pliosaur.
Professor Mike Benton, a collaborator on the project, said: "You can see these kinds of deformities in living animals, such as crocodiles or sperm whales and these animals can survive for years as long as they are still able to feed. But it must be painful. Remember that the fictional whale, Moby Dick from Herman Melville's novel, was supposed to have had a crooked jaw!"
The pliosaur from Westbury is an amazing example of how the study of disease (palaeopathologies) in fossil animals can help us to reconstruct an extinct animal's life history and behavior and to show that even a Jurassic killer could succumb to the diseases of old age.
Tag :
Sciencedaily
Terrific....First Ever Record of Insect Pollination from 100 Million Years Ago
Amber from Cretaceous deposits (110-105 my) in Northern Spain has revealed the first ever record of insect pollination. Scientists have discovered in two pieces of amber several specimens of tiny insects covered with pollen grains, revealing the first record of pollen transport and social behavior in this group of animals.
Today, more than 80% of plant species rely on insects to transport pollen from male to female flower parts. Pollination is best known in flowering plants but also exists in so-called gymnosperms, seed-producing plants like conifers. Although the most popular group of pollinator insects are bees and butterflies, a myriad of lesser-known species of flies, beetles or thrips have co-evolved with plants, transporting pollen and in return for this effort being rewarded with food.
During the last 20 years, amber from the Lower Cretaceous (110-105 my) found in the Basque country in Northern Spain has revealed many new plant and animal species, mainly insects. Here, the amber featured inclusions of thysanopterans, so-called thrips, a group of minute insects of less than 2 mm in length that feed on pollen and other plant tissues. They are efficient pollinators for several species of flowering plants.
Two amber pieces revealed six fossilized specimens of female thrips with hundreds of pollen grains attached to their bodies. These insects exhibit highly specialized hairs with a ringed structure to increase their ability to collect pollen grains, very similar to the ones of well known pollinators like domestic bees. The scientists describe these six specimens in a new genus (Gymnopollisthrips) comprising two new species, G. minor and G. major.
The most representative specimen was also studied with synchrotron X-ray tomography at the ESRF to reveal in three dimensions and at very high resolution the pollen grain distribution over the insect's body.
The results are published in the Proceedings of the National Academy of Sciences (PNAS) dated 14-18 May 2012.
The international team of scientists comprises: Enrique Peñalver and Eduardo Barrón from the Instituto Geológico y Minero de España in Madrid; Xavier Delclòs from the University of Barcelona; Andre and Patricia Nel from the Muséum national d'histoire naturelle in Paris; Conrad Labandeira from the Smithsonian Institution, Washington DC; and Carmen Soriano and Paul Tafforeau from the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. The amber samples were from the collection of the Museo de Ciencias Naturales de Álava (Spain).
The pollen grains are very small and exhibit the adherent features needed so that insects can transport them. The scientists conclude that this pollen is from a kind of cycad or ginkgo tree, a kind of living fossil of which only a few species are known to science. Ginkgos trees are either male or female, and male trees produce small pollen cones whereas female trees bear ovules at the end of stalks which develop into seeds after pollination.
For which evolutionary reason did these tiny insects, 100 million years ago, collect and transport Gingko pollen? Their ringed hairs cannot have grown due to an evolutionary selection benefitting the trees. The benefit for the thrips can only be explained by the possibility to feed their larvae with pollen. This suggests that this species formed colonies with larvae living in the ovules of some kind of gingko for shelter and protection, and female insects transporting pollen from the male Gingko cones to the female ovules to feed the larvae and at the same time pollinate the trees.
Only amber can preserve behavioral features like pollination in such rich detail over millions of years. 100 million years ago, flowering plants started to diversify enormously, eventually replacing conifers as the dominant species. "This is the oldest direct evidence for pollination, and the only one from the age of the dinosaurs. The co-evolution of flowering plants and insects, thanks to pollination, is a great evolutionary success story. It began about 100 million years ago, when this piece of amber fossil was produced by resin dropping from a tree, which today is the oldest fossil record of pollinating insects. Thrips might indeed turn out to be one of the first pollinator groups in geological history, long before evolution turned some of them into flower pollinators," concludes Carmen Soriano, who led the investigation of the amber pieces with X-ray tomography at the ESRF.
Tag :
Sciencedaily
A 'Cousin' of the Giant Panda Lived in What Is Now Zaragoza, Spain
A team of Spanish scientists have found a new ursid fossil species in the area of Nombrevilla in Zaragoza, Spain. Agriarctos beatrix was a small plantigrade omnivore and was genetically related to giant pandas, according to the authors of the study.The fossil remains of a new ursid species, Agriarctos beatrix, have been discovered in the Nombrevilla 2 site in the province of Zaragoza, Spain. Researchers from Spain's National Museum of Natural Sciences (MNCN-CSIC) and the University of Valencia suggested that this plantigrade lived during the Myocene period some 11 million years ago.
"This bear species was small, even smaller than the Sun bear -- currently the smallest bear species. It would not have weighed more than 60 kilos," as explained by Juan Abella, researcher at the Department of Paleobiology of the MNCN-CSIC and lead author of the study, published in the journal Estudios Geológicos.
Although it is difficult to determine its physical appearance given that only pieces of dental fossils have been found, scientists believe that it would have had dark fur with white spots mainly on the chest, around the eyes and possibly close to the tail.
"This fur pattern is considered primitive for bears, such as that of the giant panda whose white spots are so big that it actually seems to be white with black spots," states Abella.
Agriarctos beatrix, from the Ursidae family and related to giant pandas, would have lived in the forest and could have been more sessile that those bears that tend to hunt more, such as the brown or polar bears. According to researchers, the extinct bear would have escaped from other larger carnivores by climbing up trees.
The expert highlights that "its diet would have been similar to that of the sun bear or the spectacled bear that only eat vegetables and fruit and sometimes vertebrates, insects, honey and dead animals."
The lone bear
"We know that it was a different species to those documented up until now because of its morphological differences and the size of its teeth," confirms the scientist. "We have compared it with species of the same kind (Agriarctos) and similar kinds from the same period (Ursavus and Indarctos)."
The reasons for its extinction have yet to be determined but "the most probable cause is likely to be the opening up of the forests giving way to more open, drier spaces and the appearance of similar yet larger and more competitive species," says Abella.
The findings now date the appearance of this group related to giant pandas some two millions years later, from 9 million years ago to 11 million years ago. They could have originated in the north-east basins of the Iberian Peninsula.
Tag :
Sciencedaily
Refugees from the Ice Age: How Was Europe Repopulated?
Scientists have used DNA analysis to gain important new insights into how human beings repopulated Europe as the Ice Age relaxed its grip.
Dr Maria Pala, who is based at the University of Huddersfield -- now a key centre for archaeo-genetics research -- is the lead author of an article in the latest issue of theAmerican Journal of Human Genetics which shows how the Near East was a major source of replenishment when huge areas of European territory became habitable again, up to 19,000 years ago.
Until the new findings, it was thought that there were two principal safe havens for humans as the Ice Age, or Last Glacial Maximum, descended, approximately 26,000 years ago. They were a "Franco-Cantabrian" area roughly coinciding with northern Spain/southern France, and a "Periglacial province" on the Ukrainian plains.
Now Dr Pala and her colleagues have greatly added to this picture by analyzing large quantities of mitochondrial DNA from Europeans who belong to two major lineages -- who share a common genetic ancestor -- named J and T. It is known that these haplo-groups originated in the Middle East and until the latest research it was thought that they migrated to Europe in the Neolithic age, approximately 9,000 years ago.
The research project outlined in the American Journal of Human Genetics presents evidence that humans belonging to the J and T haplo-groups actually migrated to Europe much earlier than previously believed, as the Ice Age drew to a close.
"The end of the Last Glacial Maximum allowed people to recolonize the parts of Europe that had been deserted and this expansion allowed increase of human populations," says Sardinian-born Dr Pala, who begun research into the topic while at the University of Pavia in Italy.
She later relocated to the UK and is now a Senior Research Fellow at the University of Huddersfield, where archaeo-genetics research -- in newly equipped laboratories -- is headed by
Professor Martin Richards, a leader in a field of science which combines archaeology with genetics to learn about the early history of humans and how they colonized the planet.
In addition to purely scientific challenges and discoveries, Dr Pala believes that archaeo-genetics has important lessons to teach humanity.
"It helps us to reevaluate the perception of our identity. We are highly focused on identifying ourselves as Italians, British or whatever, but by analyzing DNA we discover that originally, not such a long time ago, we came from a common source."
Tag :
Sciencedaily
