The skeletal remains are thought to be unique as they are buried near the site of a Roman villa, making it likely that the five skeletons belonged to the owners and occupants of the villa – the first time in Britain that the graves of villa owners have been found in such close proximity to the villa itself.
Five skeletons were found; two adult males, two adult females and an elderly female – with researchers postulating that they could be the remains of three generations of the same family, who all owned the villa. The bones are thought to date from the mid-4th Century (around 350 AD).
Miles Russell, a Senior Lecturer in Archaeology at Bournemouth University and one of the archaeologists leading the dig, said, “The discovery is of great significance as it is the only time where evidence of a villa and the villa’s occupants have been found in the same location in Britain. This could provide us with significant information, never retrieved before, about the state of health of the villa owners, their ancestry and where they came from.”
Miles continued, “One of the big questions in South West is whether the villas in the South West were owned by Britons who have become Roman or owned by people from another part of the Empire who have come to exploit an under-developed rural area. All villas in this region in the South West are late-Roman – and our findings should tell us more about what life was like in this period of history. This is what what can be assessed when the bones are analysed.”
The discovery was made by staff and students from Bournemouth University, who are working on the Durotriges Big Dig project in North Dorset.
The villa itself was excavated last year by students working on the project, and the latest find is the final step in excavating this particular area of rich archaeological significance.
Paul Cheetham, Senior Lecturer in Archaeological Sciences and co-director of the project, added, “We are looking at the rural elite of late-Roman Britain, living through the economic collapse that took place during this period. These remains will shed light on the final stages of the golden age of Roman Britain.”
How nutrients are metabolised and how neurons communicate in the brain are just some of the messages coded by the 3 billion letters that make up the human genome. The detection and characterisation of the genes present in this mass of information is a complex task that has been a source of ongoing debate since the first systematic attempts by the Human Genome Project more than ten years ago.
A study led by Alfonso Valencia, Vice-Director of Basic Research at the Spanish National Cancer Research Centre (CNIO) and head of the Structural Computational Biology Group, and Michael Tress, researcher at the Group, updates the number of human genes –those that can generate proteins– to 19,000; 1,700 fewer than the genes in the most recent annotation, and well below the initial estimations of 100,000 genes. The work, published in the journal Human Molecular Genetics, concludes that almost all of these genes have ancestors prior to the appearance of primates 50 million years ago.
“The shrinking human genome,” that’s how Valencia describes the continuous corrections to the numbers of the protein-coding genes in the human genome over the years that has culminated in the approximately 19,000 human genes described in the present work. “The coding part of the genome [which produces proteins] is constantly moving,” he adds: “No one could have imagined a few years ago that such a small number of genes could make something so complex.”
The scientists began by analysing proteomics experiments; proteomics is the most powerful tool to detect protein molecules. In order to determine a map of human proteins the researchers integrated data from seven large-scale mass spectrometry studies, from more than 50 human tissues, “in order to verify which genes really do produce proteins ” says Valencia.Fewer than ten genes separate mice and men…
The results brought to light just over 12,000 proteins and the researchers mapped these proteins to the corresponding regions of the genome. They analysed thousands of genes that were annotated in the human genome, but that did not appear in the proteomics analysis and concluded: “1,700 of the genes that are supposed to produce proteins almost certainly do not for various reasons, either because they do not exhibit any protein coding features, or because the conservation of their reading frames does not support protein coding ability, “says Tress.
One hypothesis derived from the study is that more than 90% of human genes produce proteins that originated in metazoans or multicellular organisms of the animal kingdom hundreds of millions of years ago; the figure is over 99% for those genes whose origin predates the emergence of primates 50 million years ago.
“Our figures indicate that the differences between humans and primates at the level of genes and proteins are very small,” say the researchers. David Juan, author and researcher in the Valencia lab, says that “the number of new genes that separate humans from mice [those genes that have evolved since the split from primates] may even be fewer than ten.” This contrasts with the more than 500 human genes with origins since primates that can be found in the current annotation. The researchers conclude: “The physiological and developmental differences between primates are likely to be caused by gene regulation rather than by differences in the basic functions of the proteins in question.”Doing more with less…
The sources of human complexity lie more in how genes are used rather than on the number of genes, in the thousands of chemical changes that occur in proteins or in the control of the production of these proteins by non-coding regions of the genome, which comprise 90% of the entire genome and which have been described in the latest findings of the international ENCODE project, a Project in which the Valencia team participates.
The work brings the number of human genes closer to other species such as the nematode worms Caenorhabditis elegans, worms that are just 1mm long, but apparently less complex than humans. But Valencia prefers not to make comparisons: “The human genome is the best annotated, but we still believe that 1,700 genes may have to be re-annotated. Our work suggests that we will have to redo the calculations for all genomes, not only the human genome.”
The research results are part of GENCODE, a consortium which is integrated into the ENCODE Project and formed by research groups from around the world, including the Valencia team, whose task is to provide an annotation of all the gene-based elements in the human genome.
“Our data are being discussed by GENCODE for incorporation into the new annotations. When this happens it will redefine the entire mapping of the human genome, and how it is used in macro projects such as those for cancer genome analysis “, says Valencia.
Various traits unique to humans were thought to have originated in the genus Homo between 2.4 and 1.8 million years ago in Africa. Even though scientists have recognized these characteristics for a multitude of years, they are now reconsidering the true evolutionary factors that drove them.
A large brain, long legs, the ability to craft tools and prolonged maturation periods were aspects that scientists believed all evolved together at the beginning of the Homo lineage as African grasslands spread and the global climate became cooler and drier. However, new climate and fossil evidence analyzed by a group of researchers, including Smithsonian paleoanthropologist Richard Potts, Susan Antón, professor of anthropology at New York University, and Leslie Aiello, president of the Wenner-Gren Foundation for Anthropological Research, implies that these traits did not arise in one single group. Instead, it is now thought that the several key ingredients, once thought to define Homo evolved in the earlier Australopithecus ancestor between 3 and 4 million years ago, while some others emerged much later.
The research team’s findings takes an pioneering approach to integrating paleoclimate data, newly discovered fossils and understandings of the genus Homo, archaeological remains and biological studies of a vast range of mammals (including humans). The synthesis of this data led the team to conclude that the ability for early humans to adapt to changing conditions ultimately allowed the earliest of Homo to vary, survive and begin spreading from Africa to Eurasia 1.85 million years ago. Further information concerning this study can be found in the July 4 issue of Science.
Potts developed a new climate framework for East African human evolution that depicts most of the era from 2.5 million to 1.5 million years ago as a period that suffered significant climate instability including shifting intensity of annual wet and dry seasons. This framework, based on Earth’s astronomical cycles, provides the core of some of the paper’s key findings, and it implies that multiple coexisting species of Homo that overlapped geographically emerged in highly changing environments.
“Unstable climate conditions favored the evolution of the roots of human flexibility in our ancestors,” said Potts, curator of anthropology and director of the Human Origins Program at the Smithsonian’s National Museum of Natural History. “The narrative of human evolution that arises from our analyses stresses the importance of adaptability to changing environments, rather than adaptation to any one environment, in the early success of the genus Homo.”
The team took time to review the entire body of fossil evidence relevant to the origin of Homo in order to obtain a better understanding of how the human genus evolved. For example, five skulls approximately 1.8 million years old discovered at the site of Dmanisi, Republic of Georgia, expose variations in traits typically seen in Africa H. erectus but differ from the defining traits of other species of early Homo known only in Africa. Newly discovered skeletons of Australopithecus sediba (approximately 1.98 million years old) from Malapa, South Africa, also include some Homo-like features in its teeth and hands, while also containing some unique non-Homo traits in its skull and feet. The comparison of these fossils with the substantial fossil record of East Africa shows that the early diversification of Homo was a period of morphological experimentation. It therefore indicates that multiple species of Homo lived in parallel with each other.
“We can tell the species apart based on differences in the shape of their skulls, especially their face and jaws, but not on the basis of size,” said Antón. “The differences in their skulls suggest early Homo divvied up the environment, each utilizing a slightly different strategy to survive.”
Although all the Homo species had overlapping body, brain and tooth sizes, they also had larger brains and bodies than their potential ancestors, Australopithecus. According to the study, these differences and similarities indicate that the human package of traits evolved separately rather than all together and at one time.
As well as studying climate and fossil data, the research team also reviewed evidence from ancient stone tools, isotopes found in teeth and cut marks found on animal bones in East Africa.
“Taken together, these data suggest that species of early Homo were more flexible in their dietary choices than other species,” said Aiello. “Their flexible diet—probably containing meat—was aided by stone tool-assisted foraging that allowed our ancestors to exploit a range of resources.”
The team found that it is this flexibility that most likely improved the ability of human ancestors to successfully adapt to the unstable environments they were faced with and disperse from Africa. This flexibility continues to be a hallmark of human biology even today, and one that ultimately underpins the ability to occupy a vast variety of habitats throughout all over the globe. Any future research on new fossil and archaeological finds will have to concentrate on identifying specific adaptive features that originated with early Homo, which will create a much greater understanding of human evolution.
Contributing Source: Smithsonian
Header Image Source: WikiPedia
150 years after discovery and a mere 150 million years since it took flight, Archaeopteryx still has hidden mysteries that need solving: The eleventh specimen of the iconic “basal bird” turns out to have been the best preserved plumage thus far, allowing detailed comparisons to be made with other feathered dinosaurs. The fossil is still undergoing extensive examinations by a team led by Dr. Oliver Rauhut, a paleontologist in the Department of Earth and Environmental sciences at LMU Munich, who is also associated with the Bavarian State Collection for Paleontology and Geology in Munich. The primary results of their analysis of the plumage are reported in the latest issue of the journal Nature. This new information makes a major contribution to the ongoing debate over the evolution of feathers and its relation to avian flight. The data also implies that the connections between feather development and the origin of flight are potentially much more complex than what was previously thought.
“For the first time, it has become possible to examine the detailed structure of the feathers on the body, the tail and, above all, on the legs,” says Oliver Rauhut. In the case of this new specimen, the feathers are, for the most part, preserved as impressions in the rock matrix. “Comparisons with other feathered predatory dinosaurs indicate that the plumage in the different regions of the body varied widely between these species. That suggests that primordial feathers did not evolve in connection with flight-related roles, but originated in other functional contexts,” says Dr. Christian Forth of LMU and the Bavarian State Collection for Paleontology and Geology in Munich, first author on the new paper.To keep warm and to catch the eye
It has now been discovered that predatory dinosaurs (theropods) with body plumage predate Archaeopteryx and their feathers probably provided thermal insulation. Advanced species of predatory dinosaurs and primitive birds with feathered forelimbs potentially used them as balance organs when running, much like ostriches do today. Furthermore, feathers may have served as useful functions in brooding, camouflage and display. The feathers on the tail, wings and hand-limbs would have probably fulfilled functions in display, but it is very unlikely that Archaeopteryx were capable of flight. “Interestingly, the lateral feathers in the tail of Archaeopteryx had an aerodynamic form, and most probably played an important role in its aerial abilities,” says Foth.
In terms of their investigation of the plumage of the new fossil, the research team has been able to identify the taxonomical relationship between Archaeopteryx and other species of feathered dinosaur. The diversity in form and distribution of the feather tracts is particularly striking. For instance, among dinosaurs that had feathers on their legs, many had long feathers that extended as far as their toes, while others had shorter down-like plumage. “If feathers had evolved originally for flight, functional constraints should have restricted their range of variation. And in primitive birds we do see less variation in wing feathers than in those on the hind-limbs or the tail,” explains Foth.
The findings suggest that feathers obtained their aerodynamic functions secondarily: Once feathers had been invented, they could be co-opted for flight. It is even possible that the ability to fly evolved more than once within the theropods,” says Rauhut. “Since the feathers were already present, different groups of predatory dinosaurs and their descendants, the birds, could have exploited these structures in different ways.” The new discovery also contradicts with the theory that powered avian flight evolved from earlier four-winged species that had the ability to glide.A cultural treasure
Archaeopteryx represents a transitional form between reptiles and birds and is the possibly both the earliest and best-known bird fossil. It is concrete evidence that modern birds are direct descendents of predatory dinosaurs, and thus are themselves modern-day dinosaurs. The many new fossil species of feathered dinosaurs discovered in China in recent years have made it possible to place Archaeopteryx within a larger evolutionary context. Yet, when feathers first appeared and the frequencies of flight are aspects that are still undetermined.
The eleventh known specimen of Archaeopteryx is still held privately. Like all the other examples of the genus, it was discovered in the Altmuhl valley in Bavaria, which in the Late Jurassic times was located in the northern tropics, and at the bottom of a shallow sea, as all Archaeopteryx fossils found so far have been recovered from limestone deposits. The collector was not only willing to make the specimen available for study, he also had it registered on the list of protected German Cultural Treasures to ensure that it would remain accessible to science. This is a very good example of successful cooperation between private collectors and academic paleontologists,” says Rauhut. The detailed analysis of the fossil was made possible by the financial support provided by the Volkswagen Foundation.
Contributing Source: LMU Munich
Header Image Source: LMU Munich
Learning how to survive on a lean-season diet of insects such as ants and slugs, which are tricky to catch, may have progressed the development of larger brains and higher-level cognitive functions in our ancestors and other primates, suggests research from Washington University in St. Louis.
“Challenges associated with finding food have long been recognized as important in shaping evolution of the brain and cognition in primates, including humans,” said Amanda D. Melin, PhD, assistant professor of anthropology in Arts & Sciences and lead author of the study.
“Our work suggests that digging for insects when food was scarce may have contributed to hominid cognitive evolution and set the stage for advanced tool use.”
Based on a study of capuchin monkeys that took place over a five year period in Costa Rica, the research provides support for an evolutionary theory that connects the development of sensorimotor (SMI) skills, such as increased manual dexterity, tool use and problem solving, to the more creative challenges of foraging for insects and other foods that are buried, or otherwise difficult to acquire.
Published in the June 2014 Journal of Human Evolution, the study is the first to offer detailed evidence on how seasonal changes in food supplies have influenced the foraging patterns of wild capuchin monkeys.
The study is co-authored by biologist Hilary C. Young, along with anthropologists Krisztina N. Mosdossy and Linda M. Fedigan, all of the University of Calgary, Canada.
The study refers to the fact that human populations also eat buried insects on a seasonal basis and suggests that this practice was a key aspect in human evolution.
“We find that capuchin monkeys eat embedded insects year-round but intensify their feeding seasonally, during the time that their preferred food – ripe fruit – is less abundant,” Melin said. “These results suggest embedded insects are an important fallback food.”
Research that has been conducted previously has shown that fallback foods help shape the evolution of primate bodies, including the formation of strong jaws, thick teeth and specialized digestive systems in primates whose fallback diets are reliant largely on vegetation.
The study also shows that fallback foods can play a crucial role in brain evolution among primates that fall back on insect-based diets. This influence is most prominent among primates that evolve in habitats with wide seasonal variations, such as the wet-dry cycles that can be found in South American forests.
“Capuchin monkeys are excellent models for examining evolution of brain size and intelligence for their small body size, they have impressively large brains,” Melin said. “Accessing hidden and well-protected insects living in tree branches and under bark is a cognitively demanding task, but provides a high-quality reward: fat and protein, which is needed to fuel big brains.”
However, when it comes to using tools not all capuchin monkey strains and lineages are identical, and Melin’s theories may help distinguish the reason for this.
Perhaps the most significant difference between the robust (tufted, genus Sapajus) and gracile (untufted, genus Cebus) capuchin lineages is their variation in tool use. Cebus monkeys are well known for their clever food-foraging skills, such as banging snails or fruits against branches, however they are nothing compared to their Sapajus cousins when it comes to the innovative use and modification of sophisticated tools.
Melin said that one explanation is that Cebus capuchins have historically and consistently resided in tropical rainforests, whereas the Sapajus capuchins spread from their origins in the Atlantic rainforest into areas with drier, more temperate and seasonal habitats.
“Primates who extract foods in the most seasonal environments are expected to experience the strongest selection in the ‘sensorimotor intelligence’ domain, which includes cognition related to object handling,” Melin said. “This may explain the occurrence of tool use in some capuchin lineages, but not in others.”
Genetic analysis of mitochondrial chromosomes has shown that the Sapajus-Cebus diversification occurred millions of years ago in the late Miocene epoch.
“We predict that the last common ancestor of Cebus and Sapajus had a level of SMI more closely resembling extant Cebus monkeys, and that further expansion of SMI evolved in the robust lineage to facilitate increased access to varied embedded fallback foods, necessitated by more intense periods of fruit shortage,” she said.
One of the more interesting modern examples of this behavior, said Melin, is the seasonal consumption of termites by chimpanzees, whose use of tools in order to extract the protein-rich food source is a crucial survival technique in their harsh environments.So what does this mean for hominids?
It is difficult to decipher the extent of seasonal dietary variations in the fossil record; stable isotope analyses show seasonal variation in diet for at least one South African hominin, Paranthropus robustus. Other isotopic research suggests that early human diets might have included a range of extractable foods including termites, plant roots and tubers.
Modern humans are known to frequently consume insects, which are important when other animal foods are more limited.
This study suggests that the resourcefulness needed to survive on a diet of elusive insects has been a key factor in the development of uniquely human skills:
It may well have been bugs that helped shape our brains.
Contributing Source: Washington University in St. Louis
Header Image Source: Wikimedia
Tibetans gained the ability to adapt to high altitudes due to a gene they acquired when their ancestors bred with a species of human they subsequently helped push to extinction, according to a new report by scientists at the University of California, Berkeley.
An unusual variant of a gene involved in the regulation of the body’s production of hemoglobin- the molecule responsible for carrying oxygen in the blood- became widespread in Tibetans after moving onto the high-altitude plateau several thousand years ago. This variant permitted them to survive despite low oxygen levels at elevations of 15,000 feet or more, whereas most people develop thick blood at high altitudes, which leads to cardiovascular problems.
“We have very clear evidence that this version of the gene came from Denisovans,” a mystifying human relative that went extinct approximately 40,000-50,000 years ago, around the same time as the well known Neanderthals, under pressure from modern humans, said principal author Rasmus Nielsen, UC Berkeley professor of integrative biology. “This shows very clearly and directly that humans evolved and adapted to new environments by getting their genes from another species.”
He continued to say that this is the first time a gene from another species of human has been shown explicitly to help modern humans adapt to their environment.
Nielsen, along with his colleagues at BGI-Shenzen in China reported their findings on July 2nd in advance of their publication in the journal Nature.
The gene, called EPAS1, activates when oxygen levels in the blood drop, triggering production of more hemoglobin. The gene is also know as the superathlete gene because at low elevations, some variants of it help athletes quickly boost hemoglobin and therefore the oxygen-carrying capacity of their blood, increasing their endurance. At high altitude, however, the common variants of the gene increase hemoglobin and its carrier, red blood cells, too much, increasing the thickness of the blood, leading to hypertension and heart attacks, as well as low-birth weight babies and an increase in infant mortality. The variant or allele that is found in Tibetans raises hemoglobin and red blood cells only a little at high elevation, avoiding the negative side-effects that are seen in most people who relocate to elevations of more than 13,000 feet.
“We found part of the EPAS1 gene in Tibetans is almost identical to the gene in Denisovans and very different from all other humans,” Nielsen said. “We can do a statistical analysis to show that this must have come from Denisovans. There is no other way of explaining the data.”Harsh Conditions on Tibetan Plateau
The group of researchers first reported the prevalence of a high-altitude version of EPAS1 in Tibetans back in 2010, based on sequencing the genomes of numerous Han Chinese and Tibetans. Nielsen and his colleagues instigated an argument that this was due to natural selection to adapt approximately 40 percent lower oxygen levels on the Tibetan plateau. That is, people lacking the variant died before reproducing at an increased rate than those with it. About 87 percent of Tibetans now possess the high-altitude version, compared to only 9 percent of Han Chinese, who have the same common ancestor as Tibetans.
Subsequently, Nielsen and his colleagues sequenced the EPAS1 gene in a further 40 Tibetans and 40 Han Chinese. The data revealed that the high-altitude variant of EPAS1 is so unusual that it could have only originated from Denisovans. Apart from its low frequency in Han Chinese, it is not present in any other known humans, not even Melanesians, who share nearly 5 percent of their genomes with the Denisovan people. A high quality sequence of the Denisovan genome was published in 2012.
Nielsen sketched out a possible scenario leading to this finding: modern humans coming out of Africa interbred with Denisovan populations in Eurasia as they passed through the area into China, and their descendants still retain a small percentage, perhaps as small as 0.1 percent, Denisovan DNA. The group that invaded China ultimately split, with one population relocating to Tibet and the other, now known as Han Chinese, domination the lower elevations.
Nielsen and his colleagues were analyzing other genomes to determine the time in which the Denisovan interbreeding occurred; it has been found that this probably happened over a rather short period of time.
“There might be many other species from which we also got DNA, but we don’t know because we don’t have the genomes,” Nielsen said. “The only reason we can say that this bit of DNA is Denisovan is because of this lucky accident of sequencing DNA from a little bone found in a cave in Siberia. We found the Denisovan species at the DNA level, but how many other species are out there that we haven’t sequenced?”
Contributing Source: University of California- Berkeley
Header Image Source: WikiPedia
Genetic analysis of Neolithic deer hair from from the clothing of a mummy discovered in the Italian Alps links deer population to modern day western European lineage, rather than the eastern lineage that are present in the Italian Alps today, according to a study published on July 2nd, 2014 in the journal PLOS ONE by Cristina Oliveri, of the University of Camerino, Italy and colleagues.
In the Italian Alps in 1991 a Tyrolean Iceman’s body, clothing and equipment were found in an exceptional condition, being extremely well preserved. The mummy would have lived in the Copper Age, approximately 5,300 years ago, and previous analysis suggests that Neolithic red deer were a good source of clothing, food and tools. However, there is little information about the lineage of the Neolithic red deer population. Combined with current lineage information about contemporary and ancient red deer population, scientists analysed red deer hair from the mummy’s clothing. The scientists collected DNA from the hair shafts collected from the fur that the mummy wore. They proceeded to use genetic analysis, sequencing the DNA and comparing the results with phlogeny of contemporary and ancient red deer populations.
Red deer are categorised into three genetic lineages, western, eastern and North-African/Sardinian. The genetic analysis of the Neolithic deer hair that was carried out exposed that the Alpine Copper Age red deer was of western European lineage. This has highlighted a contrast, as the current populations in the Italian Alps belong to the eastern lineage. The researchers suggest that these differences in lineage may highlight the impact of different glacial refugia and postglacial recolonization processes of the European red deer population.
Contributing Source: PLOS ONE
Header Image Source: Wikimedia
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