понедельник, 4 февраля 2019 г.

The tracer dye

Remember that Wang et al. preprint at bioRxiv on the genetic prehistory of the Greater Caucasus? Well, it’s just been published at Nature Communications under a new title: Ancient human genome-wide data from a 3000-year interval in the Caucasus corresponds with eco-geographic regions.
The authors also re-worked a few other parts of the manuscript, including the abstract and figures, but most of it looks pretty much the same as the bioRxiv version from May 2018. It’s hard for me to believe that this process took more than half a year, so I’m guessing this is just how long it takes sometimes to get a paper into this journal.
In any case, the supplementary information includes a Peer Review File (see here) with a couple of interesting comments in regards to the Proto-Indo-European (PIE) homeland debate. Emphasis is mine:



Reviewer no 2: This hypothesis about the Caucasus source of Proto-Indo-European has been advanced also for slightly other reasons by David Reich and Kristian Kristiansen, so I think it should be elaborated here by the authors and they should marshall their new results to add whatever support they can. However, this hypothesis should rest on showing a sustained admixture between Maikop and Yamnaya to serve as a bridge to Yamnaya from the Caucasus (because the authors accept Yamnaya as connected to later PIE.) It is difficult to see in the results presented here a sustained gene flow from Maikop into Yamnaya, that would sustain this hypothesis. On lines 410 and 432 the authors preferred to see the Anatolian Farmer genes that appeared in Yamnaya as flowing from southeastern Europe, with a 20% WHG component, not from Maikop, without the WHG component. If most of the c. 15% Anatolian Farmer found in Yamnaya came from the west, it leaves very little room for gene flow into Yamnaya from Maikop. If the 3% WHG that makes the difference between a western and Caucasian source of Anatolian Farmer is strongly supported by their data, that makes a Caucasian origin of PIE less likely because it reduces gene flow from Maikop into the steppes. In fact it suggests that very little south-to-north gene flow occurred during the Maikop period (except into 2 individuals from a distinct, small, local genetic group different from Maikop and Yamnaya). This is puzzling and unexpected, but also it fails to support the bridge that seems to be needed.





Reply: We’re afraid that this might be a misunderstanding. There is indeed very limited gene flow between the Caucasus and the steppe groups (apart from the examples highlighted). However, we have based our PIE-related speculations on the observation that the CHG/Iranian (green) ancestry component is increasing already during the Eneolithic north of the Caucasus. This led us to propose that this might be the actual ‘tracer dye’ of an early PIE spread, which could then also accommodate the spread of PIE south of the mountain range where this ancestry component also rises in frequency resulting in a relatively homogenised dual ancestry (Anatolian + Iranian farming-related ancestry) in Chalcolithic times (see also brown arrow in Figure 2).



A misunderstanding? Perhaps, but the impression I get from reading both the preprint and paper is that the authors really wanted Maykop to have been the source of Indo-European languages on the Pontic-Caspian steppe, even if they didn’t spell this out directly. So I’m not surprised by the peer reviewer’s line of inquiry.
I think what actually happened was that the authors got it in their heads long ago that the PIE homeland was south of the Caucasus, simply because that’s what they saw when they looked at the spread, across space and time, of some exceedingly broad and very ancient genome-wide genetic components, including one such component with roots in the Caucasus and surrounds that is found both in Yamnaya and Hittite samples. And they penciled in Maykop, probably based on archeological data, as the most likely vector for the spread of this potential PIE “tracer dye” onto the steppe.
But that didn’t work out once they had a good look at their ancient DNA from the Caucasus, and it seems they couldn’t come up with a coherent alternative theory. Little wonder, considering what their ancient DNA showed: a profound genetic differentiation between the Eneolithic/Bronze Age populations of the Caucasus and the Pontic-Caspian steppe, especially in terms of paternal ancestry, which is crucial in linguistics debates.
Whatever. I’ve already said way too much on this topic, so I’m now moving on. But I’m certainly looking forward to the genotype data from this paper. Analyzing it is going to be a hoot.
See also…
PIE Urheimat poll: two or three options left
The PIE homeland controversy: January 2019 status report
R-V1636: Eneolithic steppe > Kura-Araxes?

Source


Climate change and infertility — a ticking time bomb?

Rising temperatures could make some species sterile and see them succumb to the effects of climate change earlier than currently thought, scientists at the University of Liverpool warn.











Climate change and infertility -- a ticking time bomb?
Clockwise from top left: broadcast-spawning fish such as carp; small ectothermic insects including pollinating bees;
endemic animals with limited latitudinal or elevation ranges such as the flightless cormorant; disease vectors including
mosquitoes; coral species that are important to highly diverse reefs; and endemic plant species including the Scottish
primrose [Credit: Joaquim Alves Gaspar, Charles Sharp, Toby Hudson, and David Glass]

“There is a risk that we are underestimating the impact of climate change on species survival because we have focused on the temperatures that are lethal to organisms, rather than the temperatures at which organisms can no longer breed,” explains evolutionary biologist Dr Tom Price from the University’s Institute of Integrative Biology.
Currently, biologists and conservationists are trying to predict where species will be lost due to climate change, so they can build suitable reserves in the locations they will eventually need to move to. However, most of the data on when temperature will prevent species surviving in an area is based on the ‘critical thermal limit’ or CTL – the temperature at which they collapse, stop moving or die.


In a new opinion article published in Trends in Ecology and Evolution, the researchers highlight that extensive data from a wide variety of plants and animals suggests that organisms lose fertility at lower temperatures than their CTL.


Certain groups are thought to be most vulnerable to climate-induced fertility loss, including cold-blooded animals and aquatic species. “Currently the information we have suggests this will be a serious issue for many organisms. But which ones are most at risk? Are fertility losses going to be enough to wipe out populations, or can just a few fertile individuals keep populations going? At the moment, we just don’t know. We need more data,” says Dr Price.


To help address this, the researchers propose another measure of how organisms function at extreme temperatures that focuses on fertility, which they have called the Thermal Fertility Limit or ‘TFL’.


“We think that if biologists study TFLs as well as CTLs then we will be able to work out whether fertility losses due to climate change are something to worry about, which organisms are particularly vulnerable to these thermal fertility losses, and how to design conservation programmes that will allow species to survive our changing climate.


“We need researchers across the world, working in very different systems, from fish, to coral, to flowers, to mammals and flies, to find a way to measure how temperature impacts fertility in that organism and compare it to estimates of the temperature at which they die or stop functioning,” urges Dr Price.


Source: University of Liverpool [January 31, 2019]



TANN



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Spotlight on Space Station science


ISS – International Space Station logo.


4 February 2019


Though all ESA astronauts are back on Earth, European science on the International Space Station is ongoing. Explore a few experiments underway right now in celebration of science at ESA.



Columbus module on International Space Station

Learning the ropes


Every ESA astronaut who flies to the International Space Station begins their training at the European Astronaut Centre in Cologne, Germany. Here, they learn the intricacies of ESA’s space laboratory Columbus.


Many European experiments that run on the International Space Station when ESA astronauts are not present – such as those in the commercial ICE Cubes facility – require minimal manual input. Others, like Time Perception in Microgravity continue with current International Space Station crew members.



Crew of ISS Exp 58

With the undocking of two visiting vehicles and packing the NG-10 Cygnus for departure, January was a busy month for the crew of Expedition 58 NASA astronaut Anne McClain, Canadian astronaut David Saint-Jacques and cosmonaut Oleg Kononeko. They also began upgrading an ESA facility that allows ground-based control of and telemetric data retrieval from miniaturised laboratories inside Columbus.


Little labs of life science


Taking their name from the Russian word for cube, ESA’s Kubik units were operational on board the Space Station even before the Columbus module arrived in 2008. Each 40×40 cm temperature-controlled container enables the study of life science in microgravity and can host multiple experiments at one time in separate tissue-box-sized experiment units. 



Kubik on Space Station

Because many biological systems are partially gravity-dependent, ‘removing’ the effects of gravity enables researchers to gain a broader understanding of how these systems work. Samples previously studied using Kubik facilities include: bacteria, fungi, white blood cells and stem cells from human bone marrow and umbilical cords, plant seedlings, and even swimming tadpoles. Upgrades will see this research continue into its second decade, offering even greater opportunities to examine life in space.


Keeping the rhythm


The crew also exchanged the sample chamber of European multi-user facility Electromagnetic Levitator (EML) to activate new material science experiments, and Anne donned the Circadian Rhythms hardware to begin a 36-hour recording session.



NASA astronaut Anne McClain

Led by principal investigator Hanns-Christian Gunga of Charité University Clinic’s Center For Space Medicine, Circadian Rhythms investigates the role of synchronised circadian rhythms, or the “biological clock”. 


Researchers hypothesise that a non-24-hour cycle of light and dark affects crew members’ natural rhythms. The investigation also addresses the effects of reduced physical activity, microgravity and an artificially controlled environment, as changes in body composition and body temperature can affect crew members’ circadian rhythms as well.


Data is collected using a “double sensor” placed on an astronaut’s forehead and chest. This takes continuous core temperature measurements for extended periods before, during and after flight. These measurements are corelated with crew members’ pre and post-flight melatonin levels.



International Space Station (ISS)

Initial results show core body temperature does elevate gradually during long-duration spaceflight. It also rises faster and higher during physical exercise on the Station than it does on the ground. Understanding this and other effects of spaceflight on circadian rhythms will aid the design of future space missions and provide a unique comparison for sleep disorders, autonomic nervous system disorders, and shift work-related disorders on Earth.


Looking ahead


While all this science is happening in space, ESA astronaut Luca Parmitano continues to train on the ground for his upcoming Beyond mission.


Luca recently participated in ground-based sessions for two European experiments that look at how humans judge force and manipulate objects in weightlessness, GRIP and GRASP, and learnt more about an experiment to validate the behavior of fluids under microgravity, known as Fluidics.



Luca Parmitano training for Beyond

Science is everywhere at ESA. As well as exploring the Universe and answering the big questions about our place in space we develop the satellites, rockets and technologies to get there. Science also helps us to care for our home planet. All this week we’re highlighting different aspects of science at ESA. Join the conversation with #ScienceAtESA.


Related links:


Columbus: http://www.esa.int/Our_Activities/Human_and_Robotic_Exploration/Columbus/Columbus_laboratory


ICE Cubes: http://www.esa.int/Our_Activities/Human_and_Robotic_Exploration/Research/ICE_Cubes_space_research_service_open_for_business


Time Perception in Microgravity: http://www.esa.int/spaceinvideos/Videos/2018/07/Horizons_science_perceiving_time_in_space


ESA’s Kubik units: https://www.esa.int/spaceinimages/Images/2018/02/Kubik_on_Space_Station


Electromagnetic Levitator (EML): https://www.esa.int/Our_Activities/Human_and_Robotic_Exploration/Proxima/Space_age_metals_and_plasma


Circadian Rhythms: https://www.esa.int/Our_Activities/Human_and_Robotic_Exploration/Research/Keeping_the_rhythm_in_space


GRIP: https://www.esa.int/spaceinimages/Images/2018/06/A_dexterous_laboratory_in_space


GRASP: https://www.esa.int/spaceinimages/Images/2018/06/Alexander_Gerst_during_the_Grasp_Experiment


Fluidics: https://www.esa.int/spaceinimages/Images/2017/11/Fluidics_infographic


Human and Robotic Exploration: http://www.esa.int/Our_Activities/Human_and_Robotic_Exploration


Images, Animation, Text, Credits: ESA/NASA.


Greetings, Orbiter.chArchive link


Solving the mystery of Serengeti’s vanishing wild dogs

The Serengeti, a World Heritage Site, is home to a spectacular range of carnivores, from lions to cheetahs and more. And with more than 1.5 million zebras, wildebeests and gazelles making annual migrations across the park, there’s plenty of food for them to feast on.











Solving the mystery of Serengeti's vanishing wild dogs
African wild dogs, Lycaon pictus, are not feral family pets, but an entirely separate species
[Credit: Per Harald Olsen, Norwegian University of Science and Technology]

One of the park’s lesser-known predators is the African wild dog, Lycaon pictus. These are not feral family pets, but an entirely separate species. Researchers started tracking wild dog numbers in 1964, and over the years, have watched as the numbers of wild dogs in the park dwindled.


But in 1991, the dogs simply disappeared from the Serengeti plains, and a huge scientific debate ensued.


Why did the wild dogs in the park suddenly go extinct?


Blame the researchers?


In 1992 a British researcher named Roger Burrows came up with a controversial hypothesis: it was researchers themselves who had led to the demise of the dogs.


The “Burrows hypothesis”, as it came to be called, suggested that the wild dogs were stressed when researchers immobilized them and put radio collars on them.


That stress caused the animals’ immune systems to be suppressed, the hypothesis suggested, which then allowed rabies lurking in their blood to eventually kill them. The hypothesis shook the conservation world, which has relied on tools like radio collars to track critically endangered, and often elusive, species.


Since Burrows first floated his controversial hypothesis, the debate has continued to rage.


“The implications of this hypothesis extend beyond wild dogs in the Serengeti,” said Craig Jackson, a researcher at the Norwegian Institute of Nature Research (NINA) who was first author of a new paper debunking the Burrows hypothesis. “Not only was immobilization of wildlife periodically suspended in certain countries immediately thereafter, but also the notion of researcher?induced extinction continues in the scientific literature.”


Jackson studied wild dogs in the greater Serengeti-Mara Ecosystem for his PhD at the Norwegian University of Science and Technology (NTNU). He worked with his colleagues at NINA, NTNU and the Tanzania Wildlife Research Institute (TAWIRI) to go through of all Burrows’ arguments and re-evaluate them using an alternative approach.


These three research institutes are all a part of AfricanBioServices, an EU-funded project that is investigating how climate change, population growth and changing land use affect both biodiversity and local communities in the Greater Serengeti-Mara Ecosystem, with the goal of crafting new approaches to sustainable development.


Their paper, published in the scientific journal Ecology and Evolution, shows that Serengeti wild dogs weren’t the victims of well-meaning researchers but likely left the park for another reason entirely — lions.


Missing, not extinct


Although a number of other studies have tried to debunk the Burrows argument, proponents of the hypothesis have discredited these studies because they were conducted in other ecosystems, not in the Serengeti.











Solving the mystery of Serengeti's vanishing wild dogs
There’s plenty of game for African wild dogs to eat in the greater Serengeti-Mara ecosystem. Here a pack of dogs takes
 down a wildebeest calf [Credit: Per Harald Olsen, Norwegian University of Science and Technology]

The Burrows hypothesis says that a key reason for the disappearance of the wild dogs was that their living situation in the park brought them into contact with rabies and canine distemper. So how exactly do you disprove this, especially since wild dogs have disappeared from the park?


Jackson says it’s easier than you might think.


“Although much of the scientific literature referred to the disappearance of the wild dogs from Serengeti National Park as a population ‘extinction’, the population never went extinct within the broader region,” Jackson said.


In fact, he said, the wild dog population actually survived in the eastern part of the greater Serengeti Mara Ecosystem. This population has been studied and monitored since 2005. Some of these wild dogs even had GPS collars, which showed the animals occasionally visit the park. That particular piece of information is very important, because it shows that the wild dogs had access to the park. And if they had access to the park, they could have chosen to settle there — in theory, at least.


But they didn’t.


That gave the researchers the perfect opportunity to go through all of arguments made by the Burrows proponents, re-evaluate them, and subsequently show why they are wrong.


Plenty of rabies, canine distemper


Wild dogs living outside the national park, in the Ngorongoro Conservation Area and the Loliondo Game Controlled Area, are exposed to rabies and canine distemper at levels at least as high, if not higher, than the wild dogs inside the park when they disappeared, the new paper explains.


That means that the wild dogs that Jackson and his group looked at had similar, if not worse, disease exposure than the wild dogs that Burrows and his colleagues say were exterminated by researcher handling.


So if handling caused enough stress in wild dogs in these two areas to depress their immune systems and make them susceptible to rabies or canine distemper, there was enough of a source of disease in the region to infect them.


Radio collars and relocation stress


Currently, there are about 120 animals in the region in 10 packs, most of them in Loliondo Game Controlled Area. These animals have been studied by TAWIRI researchers since 2005, including by using radio collars.


Between 2006 and 2016, 121 wild dogs from this region were immobilized and handled by researchers. Forty-five were radio-collared.


The Burrows group argued that wild dogs that had been handled by researchers “were significantly less likely to survive for 12 months after the date of first handling.” So Jackson and his colleagues looked at how well the 121 wild dogs from outside the national park survived in the year after they had been handled.


When they looked at the numbers, 87.6 per cent of the 121 dogs, or 106 animals, had survived at least 12 months after they had been handled. They also looked a numbers from when 67 wild dogs from 6 packs were translocated to Serengeti National Park, between 2012 and 2016.


Typically, when animals are relocated, they are monitored in enclosures for a period before they are released. In this case, the dogs were held for a mean of 313 days, and 95.5 per cent survived 12 months or more after handling. In contrast, when researchers looked at another group of 54 wild dogs from the same region that had been immobilized but not captured and translocated, they actually found lower survival rates of 77.8 per cent.


“Therefore, longer-term stressful interventions did not evoke disease outbreaks, and the high survival rate does not support Burrows’ hypothesis,” the researchers wrote.


Plenty of game and plenty of room


More than two decades after they disappeared, there are still no wild dogs in the plains of Serengeti National Park, even though there is plenty of game and plenty of room. Why not?











Solving the mystery of Serengeti's vanishing wild dogs
African wild dogs are opportunists, and will take advantage of any opportunity they can to eat and take care
of other needs [Credit: Per Harald Olsen, Norwegian University of Science and Technology]

Roel May (NINA), one of the co-authors of the study, thinks the answer to this question also explains why the population in the park disappeared in the first place — lions and hyenas.


“The wild dogs’ movement behaviour and home range utilization suggest that they face a trade-off between forage availability and landscape features that provide refuge, which means these are key determinants in wild dog occurrences in the Serengeti,” May said.


Wild dogs are predators, it’s true, but they can also be bullied and killed by larger predators, such as lions and hyenas. In particular, lions and hyenas are good at scaring wild dogs away from their food so they themselves can eat it, a phenomenon called kleptoparasitism.


The Serengeti is so rich and full of game for a reason. It’s high-quality habitat and it’s mostly flat, which lions and hyenas, as top predators, can preferentially choose to inhabit.


Lower level predators such as wild dogs consequently move to lower quality habitat, like the lands on the eastern edge of the park, which is hilly. The hilly habitat also provides protection for the wild dogs when they are denning and raising young, the researchers say.


“When the Serengeti wild dog population was in decline, the spotted hyena population in the park increased from 2200 to 5500, and there was a similar large increase in lion populations,” Jackson said. “When hyenas scare wild dogs away from their kills, the wild dogs can’t get enough calories to reproduce.”


The researchers say the evidence is very clear: increasing competition from lions and hyenas, combined with an outbreak of disease, are most likely what dealt the final blow to the Serengeti wild dog population in 1991, not researcher-induced deaths.


“Instead of a local extinction, the disappearance of wild dogs from the Serengeti plains was more likely a contraction of their range in response to increasing levels of competition with these large carnivores,” May said.


Not only that, using radio collars and other tools to understand animals like the wild dog is an important tool in helping to protect the species. Even if some few animal deaths do result from handling, the overall benefit for the species is positive, said Eivin Røskaft, an NTNU biologist who is also coordinator of the AfricanBioServices project.


“Of course there is a balance between disturbance and important knowledge on how to conserve large carnivores, particularly in a world where all large carnivore populations are rapidly declining,” Røskaft said.


“While animal welfare and ethical considerations should remain paramount, much of the information pertinent to management and conservation of threatened species would be impossible to attain in the absence of radio-telemetry and other techniques that require researcher intervention,” Jackson said.


Source: Norwegian University of Science and Technology [January 31, 2019]



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Don’t Split on Me! Image of the Week – February 4, 2019CIL:42513…


Don’t Split on Me! Image of the Week – February 4, 2019


CIL:42513http://cellimagelibrary.org/images/42513


Description: Pig epithelial (LLC-PK1) cells undergoing mitosis. Image shows microtubules (green) and chromosomes (purple) and was collected using a spinning disk confocal and deconvolution microscopy. Honorable Mention, 2005 Olympus BioScapes Competition.


Authors: Nasser Rusan and 2005 Olympus BioScapes Digital Imaging Competition®


Licensing: Attribution Non-Commercial No Derivatives: This image is licensed under a Creative Commons Attribution, Non-Commercial, No Derivatives License


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Ancient pandas weren’t exclusive bamboo eaters, bone evidence suggests

The giant pandas we know and love today live only in the understory of particular mountains in southwestern China, where they subsist on bamboo alone. In support of their tough and fibrous bamboo diet, they’ve got distinctive teeth, skull, and muscle characteristics along with a special pseudo-thumb, the better to grasp and hold bamboo stems, leaves, and shoots with. But according to new evidence reported in Current Biology, extinct and ancient panda species most likely had a more varied and complex diet.











Ancient pandas weren't exclusive bamboo eaters, bone evidence suggests
A wild Giant Panda in Foping Nature Reserve, feeding on bamboo [Credit: Fuwen Wei]

“It has been widely accepted that giant pandas have exclusively fed on bamboo for the last two million years,” says Fuwen Wei of Chinese Academy of Sciences. But, “our results showed the opposite.”


It’s impossible to know exactly what extinct animals ate. But researchers can get clues by analyzing the composition of stable isotopes (different forms of the same element that contain equal numbers of protons but different numbers of neutrons) in animal teeth, hair, and bones, including fossil remains. In the new study, the researchers first analyzed bone collagen of modern pandas (1970s-2000s) and other mammals from the same mountains.


The stable isotopic composition of carbon and nitrogen from modern panda and other modern mammal bone samples indicated three obvious groups: carnivores, herbivores, and giant pandas. The giant pandas were clearly unique, on account of their habit of eating bamboo. Next, Wei’s team measured bone collagen isotopes of 12 ancient pandas collected from seven archaeological sites in southern and southwestern China and compared them to the patterns they observed in modern giant pandas.


The data comparison showed that ancient and modern pandas are isotopically distinct from one another, suggesting differences in their dietary habits. There was also more variation among ancient panda species, suggesting that the niche they occupied was about three times wider than that of modern pandas. That is, ancient pandas most likely had a varied diet, similar to that of other mammalian species that lived alongside them. They were, the researchers write, “probably not exclusive bamboo feeders.”


The researchers suggest that pandas’ dietary habits have evolved in two phases. First, the pandas went from being meat eaters or omnivores to becoming dedicated plant eaters. Only later did they specialize on bamboo.


The researchers say they would now like to figure out when exactly pandas shifted to the specialized diet they have today. To find out, they plan to collect and study more panda samples from different historical times over the last 5,000 years.


Source: Cell Press [Janaury 31, 2019]



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2019 February 4 Henize 70: A Superbubble in the LMC Image…


2019 February 4


Henize 70: A Superbubble in the LMC
Image Credit & Copyright: Josep M. Drudis


Explanation: Massive stars profoundly affect their galactic environments. Churning and mixing interstellar clouds of gas and dust, stars – most notably those upwards of tens of times the mass of our Sun – leave their mark on the compositions and locations of future generations of stars. Dramatic evidence of this is illustrated in our neighboring galaxy, the Large Magellanic Cloud (LMC), by the featured nebula, Henize 70 (also known as N70 and DEM301). Henize 70 is actually a luminous superbubble of interstellar gas about 300 light-years in diameter, blown by winds from hot, massive stars and supernova explosions, with its interior filled with tenuous hot and expanding gas. Because superbubbles can expand through an entire galaxy, they offer humanity a chance to explore the connection between the lifecycles of stars and the evolution of galaxies.


∞ Source: apod.nasa.gov/apod/ap190204.html


Study finds billion-year superocean cycles in Earth’s history

Curtin university researchers believe that ancient supercontinents formed and then fell apart through alternating cycles spanning hundreds of millions of years that involved superoceans being swallowed and the restructuring of the Earth’s mantle.











Study finds billion-year superocean cycles in Earth's history
Research found that ancient supercontinents formed and then fell apart through alternating cycles
spanning hundreds of millions of years [Credit: Curtin University]

The research, published in science journal Precambrian Research, found the supercontinents assembled and broke up through alternating processes of ‘introversion’ and ‘extroversion.’


The latter process caused supercontinent Rodinia to be turned inside out by tectonic forces, thereby consuming the surrounding superocean and leading to the creation of Pangea, the supercontinent that incorporated almost all of the Earth’s landmasses.


Rodinia had formed via ‘introversion’ where the internal oceans formed during the break-up of previous supercontinent Nuna were consumed.


Lead researcher John Curtin Distinguished Professor Zheng-Xiang Li, from the School of Earth and Planetary Sciences at Curtin University, said the assembly and break-up of supercontinents occurred in alternating cycles of about 600 million years.


“In the past 30 years, researchers have discovered that Pangea-like supercontinents existed at least twice before Pangea, occurring roughly every 600 million years in what is known as the supercontinent cycle,” Professor Li said.


“More recently, researchers studying Earth’s geochemical records and formation of mineral deposits identified even longer-term variations in these cycles but it was not known why.”


Professor Li and his team of Curtin researchers, funded by the Australian Research Council’s Laureate Fellowship grant, recently discovered that the answer to this question could be found in the history of some of Earth’s deepest oceans.


“We found that supercontinents appear to assemble through two alternating processes of extroversion and introversion,” Professor Li said.


“More intriguingly, these two alternating processes determine not only whether the superocean survives, but also whether the circum-superocean Ring of Fire—like the present-day Pacific Ring of Fire – survives.


“If the Ring of Fire survives along with the superocean, then the Earth’s mantle structure maintains a similar pattern to the previous supercontinent. If not, then the mantle gets completely reorganised.


“Such alternating ways of supercontinent assembly, along with the survival or regeneration of the superocean and the Ring of Fire, led to the presence of an Earth cycle twice as long as the 600-million-year supercontinent cycle and influenced the formation of some of the planet’s resources.”


Source: Curtin University [January 31, 2019]



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‘Parc Glynllifon’ Prehistoric Inspired Landscape Art, North Wales, 2.2.19.

‘Parc Glynllifon’ Prehistoric Inspired Landscape Art, North Wales, 2.2.19.












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How predatory plankton created modern ecosystems after ‘Snowball Earth’

Around 635 to 720 million years ago, during Earth’s most severe glacial period, Earth was twice almost completely covered by ice, according to current hypotheses. The question of how life survived these ‘Snowball Earth’ glaciations, lasting up to about 50 million years, has puzzled scientists for many decades. An international team, led by Dutch and German researchers of the Max Planck Society, now found the first detailed glimpse of life after the ‘Snowball’ in the form of newly discovered ancient molecules, buried in old rocks.











How predatory plankton created modern ecosystems after 'Snowball Earth'
Discovery site of fossil fats: Max Planck researchers found 635 million year-old molecules in rock samples from the
Grand Canyon, most likely from predatory plankton. The microorganisms probably prepared the soil for today’s
ecosystems after the earth thawed again after a phase of complete glaciation
[Credit: laurasaman/unsplah]

“All higher animal life forms, including us humans, produce cholesterol. Algae and bacteria produce their own characteristic fat molecules,” says first author Lennart van Maldegem from Max Planck Institute (MPI) for Biogeochemistry, who recently moved to the Australian National University in Canberra, Australia. “Such fat molecules can survive in rocks for millions of years, as the oldest (chemical) remnants of organisms, and tell us now what type of life thrived in the former oceans long ago.”


But the fossil fats the researchers recently discovered in Brazilian rocks, deposited just after the last Snowball glaciation, were not what they suspected. “Absolutely not,” says team-leader Christian Hallmann from MPI for Biogeochemistry. “We were completely puzzled, because these molecules looked quite different from what we’ve ever seen before!”


Using sophisticated separation techniques, the team managed to purify minuscule amounts of the mysterious molecule and identify its structure by nuclear magnetic resonance in the NMR department of Christian Griesinger at Max Planck Institute for Biophysical Chemistry.


“This is highly remarkable itself,” according to Klaus Wolkenstein from MPI for Biophysical Chemistry and the Geoscience Centre of the University of Göttingen. “Never has a structure been elucidated with such a small amount of such an old molecule.” The structure was chemically identified as 25,28-bisnorgammacerane — abbreviated as BNG, as van Maldegem suggests.


Fossil fats most likely from heterotropic plankton


Yet the origin of the compound remained enigmatic. “We of course looked if we could find it elsewhere,” says van Maldegem, who then studied hundreds of ancient rock samples, with rather surprising success. “In particular the Grand Canyon rocks really were an eye-opener,” says Hallmann.


Although nowadays mostly sweltering hot, these rocks had also been buried under kilometres of glacial ice around 700 million years ago. Detailed additional analyses of molecules in Grand Canyon rocks — including presumed BNG-precursors, the distribution of steroids and stable carbon isotopic patterns — led the authors to conclude that the new BNG molecule most likely derives from heterotrophic plankton, marine microbes that rely on consuming other organisms for gaining energy.


“Unlike for example green algae that engage in photosynthesis and thus belong to autotrophic organisms, these heterotrophic microorganisms were true predators that gained energy by hunting and devouring other algae and bacteria,” according to van Maldegem.


Predatory species create room for algae and other plankton


While predation is common amongst plankton in modern oceans, the discovery that it was so prominent 635 million years ago, exactly after the Snowball Earth glaciation, is a big deal for the science community.


“Parallel to the occurrence of the enigmatic BNG molecule we observe the transition from a world whose oceans contained virtually only bacteria, to a more modern Earth system containing many more algae. We think that massive predation helped to ‘clear’ out the bacteria-dominated oceans and make space for algae,” says van Maldegem.


The resulting more complex feeding networks provided the dietary requirements for larger, more intricate lifeforms to evolve — including the lineages that all animals, and eventually we humans, derive from. The massive onset of predation probably played a crucial role in the transformation of our planet and its ecosystems to its present state.


The findings are published in Nature Communications.


Source: Max-Planck-Gesellschaft [Febuary 01, 2019]



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Rhodochrosite with Tetrahedrite, Quartz | #Geology #GeologyPage…


Rhodochrosite with Tetrahedrite, Quartz | #Geology #GeologyPage #Mineral


Location: Sweet Home Mine, Alma, Park Co., Colorado, USA


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‘Dinas Dinlle’ Iron Age Hillfort, North Wales, 2.2.19.









‘Dinas Dinlle’ Iron Age Hillfort, North Wales, 2.2.19.


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China’s Chang’e-4 Probe Wakes Up after First Lunar Night


CLEP – China Lunar Exploration Program logo.


Feb. 3, 2019


The rover and the lander of the Chang’e-4 probe have been awakened by sunlight after a long “sleep” during the first extremely cold night on the moon, the China National Space Administration (CNSA) announced on Thursday.


The lander woke up at 8:39 p.m. Wednesday, and the rover, Yutu-2 (Jade Rabbit-2), awoke at about 8:00 p.m. Tuesday, surviving their first lunar night after making the first-ever soft landing on the far side of the moon, said CNSA.



Chang’e-4 Lunar Lander. Image Credits: CNSA/CLEP

China’s Chang’e-4 probe, launched on Dec. 8 in 2018, landed on the Von Karman Crater in the South Pole-Aitken Basin on the far side of the moon on Jan. 3.


A lunar day equals 14 days on Earth, and a lunar night is the same length. The Chang’e-4 probe switched to a dormant mode during the lunar night due to the lack of solar power.



Yutu-2 Lunar Rover. Image Credits: CNSA/CLEP

Both the lander and the rover ended the dormant mode automatically according to the elevation angle of the sunlight. And the key instruments on the probe have started to work.



Image above: Chang’e 4 lander-rover relayed back by Queqiao lunar satellite (Magpie Bridge).Image Credits: CASC/CNSA.


Currently, the rover is located about 18 meters northwest of the lander. Communication and data transmission between ground control and the probe via the relay satellite Queqiao (Magpie Bridge) are stable, said CNSA.


Related article:


China’s Yutu-2 rover Enters Standby Mode for ‘Noon Nap’ as Chang’e 4 Tests Continue
https://orbiterchspacenews.blogspot.com/2019/01/chinas-yutu-2-rover-enters-standby-mode.html


For more information about China Aerospace Science and Technology Corporation (CASC), visit: http://english.spacechina.com/n16421/index.html


For more information about China National Space Administration (CNSA), visit: http://www.cnsa.gov.cn/


Images (mentioned), Text, Credits: CASC/CNSA/China Space News.


Best regards, Orbiter.chArchive link


Roman Stones and Relics Photoset 6, Chesters Roman Fort and Environs, Hadrian’s...

Roman Stones and Relics Photoset 6, Chesters Roman Fort and Environs, Hadrian’s Wall, Northumberland, 27.1.19.












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