Switching from coal to natural gas would do little for global climate, study indicates

Although the burning of natural gas emits far less carbon dioxide than coal, a new study concludes that a greater reliance on natural gas would fail to significantly slow down climate change. The study appears this week in the Springer journal Climatic Change Letters.

Posted by Biomechanism 

The software, which Wigley helped develop, simulates changes in atmospheric levels of greenhouse gases and their influences on global climate.

Tom Wigley, a senior research associate at the National Center for Atmospheric Research (NCAR), underscores in his study the complex and sometimes conflicting ways in which fossil fuel burning affects Earth’s climate. While coal use causes warming through emission of heat-trapping carbon dioxide, it also releases comparatively large amounts of sulfates and other particles that, although detrimental to the environment, cool the planet by blocking incoming sunlight.

The situation is further complicated by uncertainty over the amount of methane that leaks from natural gas operations. Methane is an especially potent greenhouse gas.

Wigley’s computer simulations indicate that a worldwide, partial shift from coal to natural gas would slightly accelerate climate change through at least 2050, even if no methane leaked from natural gas operations, and through as late as 2140 if there were substantial leaks. After that, the greater reliance on natural gas would begin to slow down the increase in global average temperature, but only by a few tenths of a degree.

“Relying more on natural gas would reduce emissions of carbon dioxide, but it would do little to help solve the climate problem,” says Wigley, who is also an adjunct professor at the University of Adelaide in Australia. “It would be many decades before it would slow down global warming at all, and even then it would just be making a difference around the edges.”

A small impact on temperatures

The burning of coal releases more carbon dioxide than other fossil fuels, as well as comparatively high levels of other pollutants, including sulfur dioxide, nitrogen oxides, and particles such as ash. Since natural gas emits lower levels of these pollutants, some energy experts have proposed greater reliance on that fuel source as a way to slow down global warming and reduce the impacts of energy use on the environment.

But the effects of natural gas on climate change have been difficult to calculate. Recent studies have come to conflicting conclusions about whether a shift to natural gas would significantly slow the rate of climate change, in part because of uncertainty about the extent of methane leaks.

Wigley’s new study attempts to take a more comprehensive look at the issue by incorporating the cooling effects of sulfur particles associated with coal burning and by analyzing the complex climatic influences of methane, which affects other atmospheric gases such as ozone and water vapor.

By running a series of computer simulations, Wigley found that a 50 percent reduction in coal and a corresponding increase in natural gas use would lead to a slight increase in worldwide warming for the next 40 years of about 0.1 degree Fahrenheit (less than 0.1 degree Celsius). The reliance on natural gas could then gradually reduce the rate of global warming, but temperatures would drop by only a small amount compared to the 5.4 degrees F (3 degrees C) of warming projected by 2100 under current energy trends.

If the rate of methane leaks from natural gas could be held to around 2 percent, for example, the study indicates that warming would be reduced by less than 0.2 degrees F (about 0.1 degree C) by 2100. The reduction in warming would be more pronounced in a hypothetical scenario of zero leaks, which would result in a reduction of warming by 2100 of about 0.2-0.3 degrees F (0.1-0.2 degrees C). But in a high leakage rate scenario of 10 percent, global warming would not be reduced until 2140.

“Whatever the methane leakage rate, you can’t get away from the additional warming that will occur initially because, by not burning coal, you’re not having the cooling effect of sulfates and other particles,” Wigley says. “This particle effect is a double-edged sword because reducing them is a good thing in terms of lessening air pollution and acid rain. But the paradox is when we clean up these particles, it slows down efforts to reduce global warming.”

In each of the leakage scenarios, the relative cooling impact of natural gas would continue beyond 2100, continuing to offset global warming by several tenths of a degree.

The study also found that methane leaks would need to be held to 2 percent or less in order for natural gas to have less of a climatic impact than coal due to the life cycle of methane. Both coal mining operations and the use of natural gas release varying amounts of methane, but the escaping gas’s influence on climate also depends on emissions of other gases, such as carbon monoxide and nitrous oxides, that affect the amount of time methane remains in the atmosphere.

A range of possible methane leaks

To compare the impacts of natural gas and coal, Wigley drew on a number of studies that have evaluated emissions of sulfur dioxide and other pollutants from coal, as well as methane associated with the use of both fuels. Rather than try to assign a fixed percentage to methane leaks from natural gas operations, which can vary widely and are difficult to measure, Wigley analyzed the impacts of leakage rates from 0 to 10 percent—a broad range that encompasses existing estimates.

To project future energy demand, Wigley used a midrange estimate by the U.S. Climate Change Science Program that assumed no changes in government energy policies. He also assumed that sulfur dioxide emissions from coal would drop sharply over the next few decades due to pollution control devices.

Wigley then analyzed the impacts of a 50 percent reduction in coal burning by using a simplified computer climate model known as MAGICC (Model for the Assessment of Greenhouse-gas Induced Climate Change), pronounced ‘magic.’ The software, which Wigley helped develop, simulates changes in atmospheric levels of greenhouse gases and their influences on global climate.

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Reference:
Wigley T. (2011) Coal to Gas: The Influence of Methane Leakage. Climate Change Letters. DOI 10.1007/s10584-011-0217-3

Microbots Spin Molecules to Swim Through Blood Vessels and Make Repairs

By Rebecca Boyle

Amyloidosis in Blood Vessels Pulmonary Pathology via Flickr

A lopsided self-propelled micromotor could drive itself through blood vessels, making repairs or delivering drugs along the route, according to researchers at Penn State. The small particles leach out a trail of material, like a microspider spinning a thread.

The motors turn on, as it were, when one side of a Janus microsphere grows a suite of molecules on one side. Eventually, the lopsided sphere creates an osmotic gradient. As fluid flows toward the area with fewer particles, the whole sphere moves.

Janus microspheres have two distinct hemispheres made of different substances. In this case, one half is gold and the other is silicon dioxide. Researchers led by Ayusman Sen at Penn State attached a molecule called a Grubbs catalyst, which induces polymerization, to the silica side. Then they added a monomer, which the catalyst strings into long chains. The monomer strings gather on the SiO2 side, which creates a mini current that sends the whole sphere moving the opposite direction.

To prove it can deliver substances, the scientists filled a gel substance with the monomer, which was slowly leached out. The micromotors moved toward the gel stream, like a single-celled organism following a trail of nutrient breadcrumbs.

This could be a handy, electricity-free way to send tiny devices into the bloodstream to do various tasks. The microspider motors could drive nanorobots that destroy tumor cells, or they could target drugs to specific organs more quickly, for instance.

The research is reported in the journal Angewandte Chemie.

Micromachines in the Bloodstream: The micromotors use a catalyst that binds asymmetrically to a Janus (two-sided) microsphere.  via Angewandte Chemie

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Where Does All Earth's Gold Come From? Precious Metals the Result of Meteorite Bombardment, Rock Analysis Finds

Gold. (Credit: © Martin Kreutz / Fotolia)

Science Daily  — Ultra high precision analyses of some of the oldest rock samples on Earth by researchers at the University of Bristol provides clear evidence that the planet's accessible reserves of precious metals are the result of a bombardment of meteorites more than 200 million years after Earth was formed.

During the formation of Earth, molten iron sank to its centre to make the core. This took with it the vast majority of the planet's precious metals -- such as gold and platinum. In fact, there are enough precious metals in the core to cover the entire surface of Earth with a four-metre thick layer.

The research is published in Nature.

The removal of gold to the core should leave the outer portion of Earth bereft of bling. However, precious metals are tens to thousands of times more abundant in Earth's silicate mantle than anticipated. It has previously been argued that this serendipitous over-abundance results from a cataclysmic meteorite shower that hit Earth after the core formed. The full load of meteorite gold was thus added to the mantle alone and not lost to the deep interior.

To test this theory, Dr Matthias Willbold and Professor Tim Elliott of the Bristol Isotope Group in the School of Earth Sciences analysed rocks from Greenland that are nearly four billion years old, collected by Professor Stephen Moorbath of the University of Oxford. These ancient rocks provide a unique window into the composition of our planet shortly after the formation of the core but before the proposed meteorite bombardment.

The researchers determined the tungsten isotopic composition of these rocks. Tungsten (W) is a very rare element (one gram of rock contains only about one ten-millionth of a gram of tungsten) and, like gold and other precious elements, it should have entered the core when it formed. Like most elements, tungsten is composed of several isotopes, atoms with the same chemical characteristics but slightly different masses. Isotopes provide robust fingerprints of the origin of material and the addition of meteorites to Earth would leave a diagnostic mark on its W isotope composition.

Dr Willbold observed a 15 parts per million decrease in the relative abundance of the isotope 182W between the Greenland and modern day rocks. This small but significant change is in excellent agreement with that required to explain the excess of accessible gold on Earth as the fortunate by-product of meteorite bombardment.

Dr Willbold said: "Extracting tungsten from the rock samples and analysing its isotopic composition to the precision required was extremely demanding given the small amount of tungsten available in rocks. In fact, we are the first laboratory world-wide that has successfully made such high-quality measurements."

The impacting meteorites were stirred into Earth's mantle by gigantic convection processes. A tantalising target for future work is to study how long this process took. Subsequently, geological processes formed the continents and concentrated the precious metals (and tungsten) in ore deposits which are mined today.

Dr Willbold continued: "Our work shows that most of the precious metals on which our economies and many key industrial processes are based have been added to our planet by lucky coincidence when the Earth was hit by about 20 billion billion tonnes of asteroidal material."

This research was funded by the Natural Environment Research Council (NERC), the Science and Technology Facilities Council (STFC) and the Deutsche Forschungsgemeinschaft (DFG)

Powered by Seaweed: Polymer from Algae May Improve Battery Performance

Igor Luzinov. (Credit: Clemson University)

Science Daily  — By looking to Mother Nature for solutions, researchers have identified a promising new binder material for lithium-ion battery electrodes that not only could boost energy storage, but also eliminate the use of toxic compounds now used to manufacture the components.

The research, the result of collaboration between scientists and engineers at Clemson University and the Georgia Institute of Technology, will be reported Sept. 8 in ScienceExpress, an online-only publication of the journal Science that publishes selected papers in advance of the journal. The project was supported by the two universities as well as by a Honda Initiation Grant and a grant from NASA.

Known as alginate, the material is extracted from common, fast-growing brown algae. In tests so far, it has helped boost energy storage and output for both graphite-based electrodes used in existing batteries and silicon-based electrodes being developed for future generations of batteries.

"Making less-expensive batteries that can store more energy and last longer with the help of alginate could provide a large and long-lasting impact on the community," said Gleb Yushin, an assistant professor in Georgia Tech's School of Materials Science and Engineering. "These batteries could contribute to building a more energy-efficient economy with extended-range electric cars, as well as cell phones and notebook computers that run longer on battery power -- all with environmentally friendly manufacturing technologies."

Working with Igor Luzinov at Clemson University, the scientists looked at ways to improve binder materials in batteries. The binder is a critical component that suspends the silicon or graphite particles that actively interact with the electrolyte that provides battery power.

"We specifically looked at materials that had evolved in natural systems, such as aquatic plants which grow in saltwater with a high concentration of ions," said Luzinov, a professor in Clemson's School of Materials Science and Engineering. "Since electrodes in batteries are immersed in a liquid electrolyte, we felt that aquatic plants -- in particular, plants growing in such an aggressive environment as saltwater -- would be excellent candidates for natural binders."

Finding just the right material is an important step toward improving the performance of lithium-ion batteries, which are essential to a broad range of applications, from cars to cell phones. The popular and lightweight batteries work by transferring lithium ions between two electrodes -- a cathode and an anode -- through a liquid electrolyte. The more efficiently the lithium ions can enter the two electrodes during charge and discharge cycles, the larger the battery's capacity will be.

Existing lithium-ion batteries rely on anodes made from graphite, a form of carbon. Silicon-based anodes theoretically offer as much as a tenfold capacity improvement over graphite anodes, but silicon-based anodes so far have not been stable enough for practical use.

Among the challenges for binder materials are that anodes to be used in future batteries must allow for the expansion and contraction of the silicon nanoparticles and that existing electrodes use a polyvinylidene fluoride binder manufactured using a toxic solvent.

Alginates -- low-cost materials that already are used in foods, pharmaceutical products, paper and other applications -- are attractive because of their uniformly distributed carboxylic groups. Other materials, such as carboxymethyl cellulose, can be processed to include the carboxylic groups, but that adds to their cost and does not provide the natural uniform distribution of alginates.

The alginate is extracted from the seaweed through a simple soda-based (Na2CO3) process that generates a uniform material. The anodes then can be produced through an environmentally friendly process that uses a water-based slurry to suspend the silicon or graphite nanoparticles. The new alginate electrodes are compatible with existing production techniques and can be integrated into existing battery designs, Yushin said.

Use of the alginate may help address one of the most difficult problems limiting the use of high-energy silicon anodes. When batteries begin operating, decomposition of the lithium-ion electrolyte forms a solid electrolyte interface on the surface of the anode. The interface must be stable and allow lithium ions to pass through it, yet restrict the flow of fresh electrolyte.

With graphite particles, whose volume does not change, the interface remains stable. However, because the volume of silicon nanoparticles changes during operation of the battery, cracks can form and allow additional electrolyte decomposition until the pores that allow ion flow become clogged, causing battery failure. Alginate not only binds silicon nanoparticles to each other and to the metal foil of the anode, but they also coat the silicon nanoparticles themselves and provide a strong support for the interface, preventing degradation.

Thus far, the researchers have demonstrated that the alginate can produce battery anodes with reversible capacity eight times greater than that of today's best graphite electrodes. The anode also demonstrates a coulombic efficiency approaching 100 percent and has been operated through more than 1,000 charge-discharge cycles without failure.

For the future, the researchers -- who, in addition to Yushin and Luzinov, included Igor Kovalenko, Alexandre Magasinski, Benjamin Hertzberg and Zoran Milicev from Georgia Tech; and Bogdan Zdyrko and Ruslan Burtovyy from Clemson -- hope to explore other alginates, boost performance of their electrodes and better understand how the material works.

Alginates are natural polysaccharides that help give brown algae the ability to produce strong stalks as much as 60 meters long. The seaweed grows in vast forests in the ocean and also can be farmed in wastewater ponds.

"Brown algae is rich in alginates and is one of the fastest-growing plants on the planet," said Luzinov, who also is a member of Clemson's Center for Optical Materials Science and Engineering Technologies (COMSET). "This is a case in which we found all the necessary attributes in one place: a material that not only will improve battery performance, but also is relatively fast and inexpensive to produce and is considerably more safe than the some of the materials that are being used now."

New Method to Grow Synthetic Collagen Unveiled: New Material May Find Use in Reconstructive Surgery, Cosmetics, Tissue Engineering

Rice University researchers Lesley O'Leary (left) and Jeffrey Hartgerink have unveiled a new method for making synthetic collagen, which could prove useful for regenerating new tissues and organs from stem cells. (Credit: Jeff Fitlow/Rice University)

Science Daily  — In a significant advance for cosmetic and reconstructive medicine, scientists at Rice University have unveiled a new method for making synthetic collagen. The new material, which forms from a liquid in as little as an hour, has many of the properties of natural collagen and may prove useful as a scaffold for regenerating new tissues and organs from stem cells.

Collagen, the most abundant protein in the body, is a key component of many tissues, including skin, tendons, ligaments, cartilage and blood vessels. Biomedical researchers in the burgeoning field of regenerative medicine, or tissue engineering, often use a combination of stem cells and collagen-like materials in their attempts to create laboratory-grown tissues that can be transplanted into patients without risk of immunological rejection.

"Our work is significant in two ways," said Rice's Jeffrey Hartgerink, the lead author of a new paper about the research in Nature Chemistry. "Our final product more closely resembles native collagen than anything that's previously been made, and we make that material using a self-assembly process that is remarkably similar to processes found in nature."

Animal-derived collagen, which has some inherent immunological risks, is the form of collagen most commonly used in reconstructive and cosmetic surgery today. Animal-derived collagen is also used in many cosmetics.

Despite the abundance of collagen in the body, deciphering or recreating it has not been easy for scientists. One reason for this is the complexity collagen exhibits at different scales. For example, just as a rope is made of many interwoven threads, collagen fibers are made of millions of proteins called peptides. Like a rope net that can trap and hold items, collagen fibers can form three-dimensional structures called hydrogels that trap and hold water.

"Our supramolecules, fibers and hydrogels form in a similar way to native collagen, but we start with shorter peptides," said Hartgerink, associate professor of chemistry and of bioengineering.

With an eye toward mimicking collagen's self-assembly process as closely as possible, Hartgerink's team spent several years perfecting its design for the peptides.

Hartgerink said it's too early to say whether the synthetic collagen can be substituted medically for human or animal-derived collagen, but it did clear the first hurdle on that path; the enzyme that the body uses to break down native collagen also breaks down the new material at a similar speed.

A faculty investigator at Rice's BioScience Research Collaborative, Hartgerink said scientists must next determine whether cells can live and grow in the new material and whether it performs the same way in the body that native collagen does. He estimated that clinical trials, if they prove warranted, are at least five years away.

The paper's co-authors include Rice graduate students Lesley O'Leary, Jorge Fallas, Erica Bakota and Marci Kang. The research was funded by the National Science Foundation, the Robert A. Welch Foundation and the Norman Hackerman Advanced Research Program of Texas

800,000 Years of Abrupt Climate Variability: Earth's Climate Is Capable of Very Rapid Transitions

Iceberg in Greenland. (Credit: © Martin Schwan / Fotolia)

Science Daily  — An international team of scientists, led by Dr Stephen Barker of Cardiff University, has produced a prediction of what climate records from Greenland might look like over the last 800,000 years.

Drill cores taken from Greenland's vast ice sheets provided the first clue that Earth's climate is capable of very rapid transitions and have led to vigorous scientific investigation into the possible causes of abrupt climate change.

Such evidence comes from the accumulation of layers of ancient snow, which compact to form the ice-sheets we see today. Each layer of ice can reveal past temperatures and even evidence for the timing and magnitude of distant storms or volcanic eruptions. By drilling cores in the ice scientists have reconstructed an incredible record of past climates. Until now such temperature records from Greenland have covered only the last 100,000 years or so.

The team's reconstruction is based on the much longer ice core temperature record retrieved from Antarctica and uses a mathematical formulation to extend the Greenland record beyond its current limit.

Dr Barker, Cardiff School of Earth and Ocean Sciences said: "Our approach is based on an earlier suggestion that the record of Antarctic temperature variability could be derived from the Greenland record.

"However, we turned this idea on its head to derive a much longer record for Greenland using the available records from Antarctica."

The research published in the journal Science (Sept. 8) demonstrates that abrupt climate change has been a systemic feature of Earth's climate for hundreds of thousands of years and may play an active role in longer term climate variability through its influence on ice age terminations.

Dr Barker added: "It is intriguing to get an insight into what abrupt climate variability may have looked like before the Greenland records begin. We now have to wait until longer Greenland records are produced so that we can see how successful our prediction is."

The new predictions provide an extended testing bed for the climate models that are used to predict future climate variability.

The collaborative research was funded in part by a Leverhulme Trust Philip Leverhulme Prize awarded to Dr Barker at Cardiff University. The prize recognises the achievement and potential of outstanding researchers at an early stage in their careers but who have already acquired an international reputation for their work. The Natural Environment Research Council and National Science Foundation in the United States also funded the research.

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Names, not social networks, bind us to global cultural and ethnic communities

 Other Sciences / Mathematics 
Links between hundreds of millions of names belonging to people all around the world have been analysed by geographers from UCL and the University of Auckland. The results reveal how our forenames and surnames are connected in distinct global networks of cultural, ethnic and linguistic communities.

The researchers’ methods could be of use to social scientists and health researchers investigating migration, identity and integration.

After studying the names of 118 million individuals, from 17 different countries, the team can reveal for the first time the existence of global ‘naming networks’ of linked forenames and surnames, providing a valuable representation of cultural, ethnic and linguistic population structure around the world.

“Previously, in order to try to classify and map populations using people’s names you first needed to compile a comprehensive ‘name dictionary’ identifying the cultural ethnic and linguistic origins of each name,” says author Dr. Pablo Mateos of UCL’s Department of Geography. “It is difficult to compile the extremely large ‘name dictionaries’ required to cover complete national populations and there were inevitable inconsistencies in the way individual names were interpreted and categorised.

“Rather than use a ‘name dictionary’, our approach has been to focus on the links between surnames and forenames. When you combine millions of these links into networks you see clusters emerge. They reveal the cultural baggage involved in the way in which we bestow forenames on babies and pass surnames from one generation to the next, even long after migration to a different cultural setting has occurred,” continues Dr. Mateos.

“We’ve shown how names can be used to ‘automatically’ classify individuals into cultural ethnic and linguistic communities, covering complete populations. By using repositories of names, such as telephone directories and electoral registers, we are able to identify ethnicity when no other alternative data source exists - something which could be extremely useful for future studies of public health, demography, ethnic segregation and migrant integration.”

The article clearly demonstrates that the way in which people choose their children’s names is far from random, instead reflecting cultural and kinship affiliations, geographical factors and social stratification even in today’s highly interconnected world. It shows how it is possible to highlight the degree of isolation, integration or overlap between population groups in a rapidly globalising world and has important implications for research in population genetics, public health, and social science.

More information: PLoS ONE article: http://dx.plos.org … pone.0022943 
'Zoomable' image (1) 
'Zoomable' image (2)

Provided by University College London

"Names, not social networks, bind us to global cultural and ethnic communities." September 8th, 2011. http://www.physorg.com/news/2011-09-social-networks-global-cultural-ethnic.html

Posted by
Robert Karl Stonjek

Humans naturally cooperative, altruistic, social

 Other Sciences / Social Sciences 

The condition of man is a condition of war, wrote 17th-century philosopher Thomas Hobbes. A quick glance through history books and today's news headlines certainly seems to support the longstanding idea that humans by nature are aggressive, selfish and antagonistic.

But this view simply doesn't fit with scientific facts, write researchers featured in the new book "Origins of Altruism and Cooperation" (Springer, 2011), edited by Robert W. Sussman, PhD, and C. Robert Cloninger, MD. The book's authors argue that humans are naturally cooperative, altruistic and social, only reverting to violence when stressed, abused, neglected or mentally ill.

The book, which now is available, presents evidence supporting this idea from a range of academic perspectives, including anthropology, psychiatry, biology, sociology, religion, medicine and more.

"Cooperation isn't just a byproduct of competition, or something done only because both parties receive some benefit from the partnership," says Sussman, professor of physical anthropology in Arts & Sciences. "Rather, altruism and cooperation are inherent in primates, including humans."

For example, Sussman says, chimpanzees have been observed to adopt unrelated, orphaned infants, despite the significant amount of effort and time required to care for the infants.

Sussman and Cloninger write in the book's preface that examining the influences that underlie human behavior is critical to understanding why conflicts arise among peoples and nations in the modern world and to finding the best ways to promote peaceful, productive interaction among humans worldwide.

"Prosocial behavior is an essential component of health and happiness in human beings," says Cloninger, the Wallace Renard Professor of Psychiatry at the School of Medicine. "Selfish and uncooperative behavior, on the other hand, is a sign of mental dysfunction because it is strongly associated with life dissatisfaction and ill health."

In addition to chapters co-authored by Sussman and Cloninger, the book includes articles by two other WUSTL faculty members — Peter Benson, PhD, assistant professor of sociocultural anthropology, and Jane Phillips-Conroy, PhD, professor of anatomy and neurobiology and of anthropology — and other academic experts from around the world.

Topics of the book's chapters — which range from relationships among howler monkeys to the influences of modern Western culture on human spirituality — were taken from discussions and presentations held at a 2009 conference at WUSTL titled "Man the Hunted: The Origin and Nature of Human Sociality, Altruism and Well-Being."

The conference, organized by Sussman and Cloninger, was the first of its kind to bring together international academics across disciplines to examine the evolution of cooperation, altruism and sociality in primates and humans.

More information: For more information about the book "Origins of Altruism and Cooperation," visitspringer.com/life+sciences/behavioural/book/978-1-4419-9519-3

Provided by Washington University in St. Louis

"Humans naturally cooperative, altruistic, social." September 8th, 2011. http://www.physorg.com/news/2011-09-humans-naturally-cooperative-altruistic-social.html

Posted by
Robert Karl Stonjek

Human brain evolution, new insight through X-rays

 Other Sciences / Archaeology & Fossils 

This is a 3-D rendering of the skull of Australopithecus sediba made from X-ray data gathered an experiment at the ESRF beamline ID19. Credit: ESRF/P. Tafforeau

A paper published today in Science reveals the highest resolution and most accurate X-ray scan ever made of the brain case of an early human ancestor. The insight derived from this data is like a powerful beacon on the hazy landscape of brain evolution across the transition fromAustralopithecus to Homo.

The publication is part of a series of five papers based on new evidence pertaining to various aspects of the anatomy of the species Australopithecus sediba (announced in April 2010 by Berger et al.) published in Science on 9 September 2011. Led by the University of the Witwatersrand in Johannesburg (South Africa), over 80 scientists from numerous institutes in Germany, the U.S., UK, Australia, Germany South Africa and Switzerland worked on the project. The work on the brain includes a scientist from the European Synchrotron Radiation Facility (ESRF) in Grenoble (France), where the X-ray micro-tomography scan was performed.

The exceptionally well-preserved cranium of MH 1 (Australopithecus sediba) was scanned at the ESRF at a resolution (3-D pixel size) of around 45 microns, just below the size of a human hair. Thanks to this high resolution, incredible details of the anatomy of sediba's endocast could be revealed.

According to Prof. Lee Berger from the University of the Witwatersrand in Johannesburg (South Africa) who found the fossil in 2009, "the many very advanced features found in the brain and body make it possibly the best candidate ancestor for our genus, the genus Homo, more so than previous discoveries such as Homo habilis."

This image shows a comparison of a classical computer tomography (CT) scan (left) with a scan using synchrotron microtomography at the ESRF (right). The much higher resolution and contrast are clearly visible. The lower part depicts a zoom-in view of an area which on the upper part is indicated with a square. This area includes a tooth and a cavity in the skull. Credit: ESRF/P. Tafforeau

Humans have a very large brain relative to their body size, about four times that of chimpanzees. Evolution from the brain of our shared ancestor with chimpanzees has seen this radical size increase. However, the reconstructed endocast (volume of the cranium) of MH1 is surprisingly small, with a volume of 420 cm³, on average only about 40 cm3 larger than chimpanzees.

The study of this brain shows a surprising mix of characteristics. Its overall shape resembles humans more than chimpanzees and, given its small volume, this result is consistent with a model of gradual neural (brain) reorganisation in the front part of the brain. "Indeed, one of our major discoveries is that the shape and form of sediba's brain is not consistent with a model of gradual brain enlargement, which has been hypothesised previously for the transition from Australopithecus to Homo", adds Dr Kristian Carlson from the University of the Witwatersrand, who is the main author of the paper.

Use of synchrotron X-rays was instrumental for this discovery. The external shape of a brain is reflected, like in a mould, in the inner surface of a cranium. By mapping the contours of this internal surface, an image of the original brain located in the skull can therefore be produced. However, the skull of MH-1 was not emptied from bedrock after its discovery, and only the powerful X-rays at the ESRF could penetrate deep into the fossil to reveal the cranium's interior shape at the desired resolution. Leaving the rock inside the cranium also ensured that its delicate inner surface was not damaged or altered during its extraction.

This image shows a reconstruction of the skull of MH1 (partially transparent) with the brain endocast depicted in green. Dentition also visible and the specimen is viewed from slightly above and anterolateral. Credit: Witwatersrand University/K. Carlson

"The ESRF is the most powerful installation worldwide for scanning fossils, setting the standard for what can be achieved during non-destructive studies of internal structures of fossils," concludes Paul Tafforeau, staff scientists at the ESRF and a co-author of the paper.

More information: The Endocast of MH 1, Australopithecus sediba, Kristian J. Carlson, Dietrich Stout, Tea Jashashvili, Darryl J. de Ruiter, Paul Tafforeau, Keely Carlson, Lee R. Berger, SCIENCE 9 September 2011

Provided by European Synchrotron Radiation Facility

"Human brain evolution, new insight through X-rays." September 8th, 2011.http://www.physorg.com/news/2011-09-human-brain-evolution-insight-x-rays.html

Posted by
Robert Karl Stonjek

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Sediba hominid skull hints at later brain evolution

Other Sciences / Archaeology & Fossils 

An analysis of a skull from the most complete early hominid fossils ever found suggests that the large and complex human brain may have evolved more rapidly than previously realized, and at a later time than some other human characteristics.

While some features of Australopithecus sediba were more human-like, most notably the precision-grip hand, the brain was more ape-like, says Emory University anthropologist Dietrich Stout. "It's basically a primitive brain that looks a lot like other austrolopiths, although you can see what could be the first glimmerings of a reorganization to a more human pattern."

Stout is a member of the team that analyzed a virtual endocast of the skull, which dates back 2 million years, to the pivotal period when the human family emerged. The resulting paper will be among those on A. sediba appearing in a special issue of Science on September 9.

If A. sediba is a human ancestor, as some have proposed, then its fossils could help resolve long-standing debates about human brain evolution, Stout says.

"The brain defines humanity, leading early anthropologists to expect that the brain changed first, and then the rest of the body followed," Stout says. "More recently, it has been assumed that the brain and other human traits evolved together."

The A. sediba find suggests a more "mosaic" pattern of evolution, he says. "The more modern hand paired with a primitive brain is a cautionary tale for what inferences can be drawn about a whole body from fossil fragments."

The new species was discovered in a region of South Africa known as the Cradle of Humanity, by paleontologist Lee Berger of University of the Witwatersrand (Wits) in Johannesburg. After announcing the find in 2010, Berger and colleagues began making the case that A. sediba may be the bridge between more primitive austropiths and the Homo genus. The debate over whether A. sediba is a human ancestor will likely continue, even as more material is excavated from a limestone cave called Malapa, one of the richest hominid fossil sites ever found.

"The site is especially exciting because the A. sediba skeletons are nearly complete," Stout says. "We can relate the face to the hand and the body and the brain of a single individual. A. sediba is represented by the most complete hominid skeletons we have, until we get up to the Neanderthals."

Stout studies the relationship between stone tools and brain evolution, and is an expert in functional adaptation of neuroanatomy. He was invited to assist in the analysis of the cranium of a young A. sediba male, estimated to be 12 to 13 years old at the time of death, with brain growth essentially complete. The research was led by Kristian Carlson of Wits and also included other researchers from Wits; Indiana University; the Georgian National Museum of Tibilisi, Georgia; the University of Zurich; Texas A&M University; and the European Synchroton Radiation Facility.

The virtual endocast gives a three-dimensional view of the surface features of the cranium, which was missing only part of the right side and the back. The high-resolution images reveal bumps and ridges and even impressions from blood vessels.

"You can actually see the morphology of the brain inside a skull," Stout says. "Bone is a lot more alive and plastic than many people realize. It's constantly being remodeled and shaped and the growing brain does a lot to shape the skull around it."

The researchers estimate that the brain was 420 cubic centimeters. "That's tiny and about what you'd expect for a chimpanzee," Stout says.

The face, however, of A. sediba was far less protruded than that of a chimpanzee. "We don't fully understand how the human face got smaller and tucked under the brain case, although that may have a lot to do with diet and chewing," Stout says. "That further complicates matters. The relationship of human brain evolution to cognitive changes and other biological and behavioral changes is something we have to keep looking at."

The researchers took a band of measurements on the underside of the A. sediba frontal lobes and did a comparative analysis with humans, chimpanzees and other hominids.

While the A. sediba brain clearly was not a human configuration, a surface bump shows possible foreshadowing of Broca's area, a region of the human brain associated with speech and language, Stout says. "It's a big leap, however, to go from a surface bump to really understanding what the cells were doing beneath it," he adds.

The researchers plan to expand the analysis, gathering data from more scans of chimpanzee skulls and more hominid fossil specimens from East and South Africa. "We want to put as many dots on a comparative graph as we can, to help show us where A. sediba fits in," Stout says.

Use of simple stone tools by hominids began about 2.5 million years ago. Was A. sediba a toolmaker? Its hands appear associated with that activity, Stout says, but the evidence is still incomplete. "For now, A. sediba raises more questions than it answers."

Provided by Emory University

"Sediba hominid skull hints at later brain evolution." September 8th, 2011. http://www.physorg.com/news/2011-09-sediba-hominid-skull-hints-brain.html

Posted by
Robert Karl Stonjek

Brain stent cannot prevent stroke: study

English.news.cn    A device inserted into the brain to prevent fatal strokes likely does more harm for high-risk patients, according to a new study. Stroke is the fourth-leading cause of death and a leading cause of disability in the United States. Researchers involved in the study carried in the New England Journal of Medicine tracked 451 patients in 50 medical centers who had recently suffered a stroke or stroke-like symptoms caused by narrowing of a major brain artery. As a result, 14.7 percent of patients in the stenting group had a stroke or died within the first 30 days, whereas 5.8 percent of patients in the group that received only drugs and underwent lifestyle changes. The Wingspan device, which expands a major artery in the brain to help improve blood flow, is the only system approved by the U.S. Food and Drug Administration for certain high-risk stroke patients. "Although technological advances have brought intracranial stenting into practice, we have now learned that, when tested in a large group, this particular device did not lead to a better health outcome," said Dr. Walter Koroshetz, deputy director of NINDS, part of the government's National Institutes of Health. Marc Chimowitz of the Medical University of South Carolina, who led the study, said the findings have immediate implications for doctors. And some researchers who were part of the study said they still think there may be a place for stents. (Agencies)