6th mass extinction event could happen by 2100 – study

Over the past 540 million years Earth has suffered five mass extinction events, the worst of which wiped out more than 9 per cent of marine life on the planet. A new study has suggested that the next such catastrophe might not be too far away.

Massachusetts Institute of Technology (MIT) geophysicist and mathematician, Daniel Rothman has been busy studying previous mass extinctions. He reckons the next one might be a mere 83 years away.

The previous five catastrophic events each unfolded over millions of years and involved the natural cycle of carbon through the oceans and atmosphere being disturbed, resulting, in some cases, the death of almost all life on Earth.

The award-winning mathematician identified two “thresholds of catastrophe” that, if exceeded, would upset the natural order of the cycle, leading to an unstable environment and eventually a mass extinction.

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The first relates to changes in the carbon cycle over a period of thousands or millions of years. A mass extinction will occur if the rate of change in the cycle occurs faster than global ecosystems can adapt.

The second pertains to the size or magnitude of the carbon flux over a shorter period, as has been the case over the last century.

Therein lies a problem, however, as Rothman says“How can you really compare these great events in the geologic past, which occur over such vast timescales, to what's going on today, which is centuries at the longest?”

“So I sat down one summer day and tried to think about how one might go about this systematically.”

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Following this, he devised a mathematical formula to determine the total mass of carbon added to the oceans during each event, after which “it became evident that there was a characteristic rate of change that the system basically didn't like to go past.”

Rothman estimates this to be 310 gigatons. He thinks that given the rise of carbon dioxide over the last century, a sixth mass extinction could be on the way as estimates suggest that humans will add roughly 310 gigatons to the cycle by 2100.

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“This is not saying that disaster occurs the next day,” Rothman said. “It’s saying that, if left unchecked, the carbon cycle would move into a realm which would be no longer stable, and would behave in a way that would be difficult to predict. In the geologic past, this type of behavior is associated with mass extinction.”

Rothman's paper was published Wednesday in the journal Science Advances.

What makes alcoholics drink? Research shows it's more complex than supposed

What makes alcoholics drink? New research has found that in both men and women with alcohol dependence, the major factor predicting the amount of drinking seems to be a question of immediate mood. They found that suffering from long-term mental health problems did not affect alcohol consumption, with one important exception: men with a history of depression had a different drinking pattern than men without a history of depression; surprisingly those men were drinking less often than men who were not depressed

"This work once again shows that alcoholism is not a one-size-fits-all condition," said lead researcher, Victor Karpyak (Mayo Clinic, MN, USA). "So the answer to the question of why alcoholics drink is probably that there is no single answer; this will probably have implications for how we diagnose and treat alcoholism."

The work, presented at the ECNP congress by researchers from the Mayo Clinic*, determined the alcohol consumption of 287 males and 156 females with alcohol dependence over the previous 90 days, using the accepted Time Line Follow Back method and standardized diagnostic assessment for life time presence of psychiatric disorders (PRISM); they were then able to associate this with whether the drinking coincided with a positive or negative emotional state (feeling "up" or "down"), and whether the individual had a history of anxiety, depression (MDD) or substance abuse.

The results showed that alcohol dependent men tended to drink more alcohol per day than alcohol dependent women. As expected, alcohol consumption in both men and women was associated with feeling either up or down on a particular day, with no significant association with anxiety or substance use disorders. However, men with a history of major depressive disorder had fewer drinking days (p=0.0084), and fewer heavy drinking days (p=0.0214) than men who never a major depressive disorder.

Victor Karpyak continued: "Research indicates that many people drink to enhance pleasant feelings, while other people drink to suppress negative moods, such as depression or anxiety. However, previous studies did not differentiate between state-dependent mood changes and the presence of clinically diagnosed anxiety or depressive disorders. The lack of such differentiation was likely among the reasons for controversial findings about the usefulness of antidepressants in treatment of alcoholics with comorbid depression.

This work will need to be replicated and confirmed, but from what we see here, it means that the reasons why alcoholics drink depend on their background as well as the immediate circumstances. There is no single reason. And this means that there is probably no single treatment, so we will have to refine our diagnostic methods and tailor treatment to the individual. It also means that our treatment approach may differ depending on targeting different aspects of alcoholism (craving or consumption) and the alcoholic patient (i.e. man or a woman) with or without depression or anxiety history to allow really effective treatment."

Commenting, Professor Wim van den Brink (Professor of Psychiatry and Addiction at the Academic Medical Centre, University of Amsterdam) said:

"This is indeed a very important issue. Patients with an alcohol use disorder often show a history of other disorders, including mood and anxiety disorders, they also often present with alcohol induced anxiety and mood disorders and finally the may report mood symptoms that do not meet criteria for a mood or anxiety disorder (due to a failure to meet the minimal number of criteria or a duration of less than two weeks). All these different conditions may influence current levels or patterns of drinking.

The current study seems to show that the current presence of mood/anxiety symptoms is associated with more drinking in both male and female alcoholics, whereas a clinical history of major depression in male alcoholics is associated with lower current dinking levels. Although, the study does not provide a clear reason for this difference, it may have consequences for treatment. For example, antidepressant treatment of males with a history major depression may have no effect on drinking levels. However, these findings may also result from residual confounding, e.g. patients with a history of major depression might also be patients with a late age of onset of their alcohol use disorder and this type of alcohol use disorder is associated with a different pattern of drinking with more daily drinking and less heavy drinking days and less binging. More prospective studies are needed to resolve this important but complex clinical issue."

*This work was presented on Sunday 3rd September, 2017.

Moon has a water-rich interior

A new study of satellite data finds that numerous volcanic deposits distributed across the surface of the Moon contain unusually high amounts of trapped water compared with surrounding terrains. The finding of water in these ancient deposits, which are believed to consist of glass beads formed by the explosive eruption of magma coming from the deep lunar interior, bolsters the idea that the lunar mantle is surprisingly water-rich.

Scientists had assumed for years that the interior of the Moon had been largely depleted of water and other volatile compounds. That began to change in 2008, when a research team including Brown University geologist Alberto Saal detected trace amounts of water in some of the volcanic glass beads brought back to Earth from the Apollo 15 and 17 missions to the Moon. In 2011, further study of tiny crystalline formations within those beads revealed that they actually contain similar amounts of water as some basalts on Earth. That suggests that the Moon's mantle -- parts of it, at least -- contain as much water as Earth's.

"The key question is whether those Apollo samples represent the bulk conditions of the lunar interior or instead represent unusual or perhaps anomalous water-rich regions within an otherwise 'dry' mantle," said Ralph Milliken, lead author of the new research and an associate professor in Brown's Department of Earth, Environmental and Planetary Sciences. "By looking at the orbital data, we can examine the large pyroclastic deposits on the Moon that were never sampled by the Apollo or Luna missions. The fact that nearly all of them exhibit signatures of water suggests that the Apollo samples are not anomalous, so it may be that the bulk interior of the Moon is wet."

The research, which Milliken co-authored with Shuai Li, a postdoctoral researcher at the University of Hawaii and a recent Brown Ph.D. graduate, is published in Nature Geoscience.

Detecting the water content of lunar volcanic deposits using orbital instruments is no easy task. Scientists use orbital spectrometers to measure the light that bounces off a planetary surface. By looking at which wavelengths of light are absorbed or reflected by the surface, scientists can get an idea of which minerals and other compounds are present.

The problem is that the lunar surface heats up over the course of a day, especially at the latitudes where these pyroclastic deposits are located. That means that in addition to the light reflected from the surface, the spectrometer also ends up measuring heat.

"That thermally emitted radiation happens at the same wavelengths that we need to use to look for water," Milliken said. "So in order to say with any confidence that water is present, we first need to account for and remove the thermally emitted component."

To do that, Li and Milliken used laboratory-based measurements of samples returned from the Apollo missions, combined with a detailed temperature profile of the areas of interest on the Moon's surface. Using the new thermal correction, the researchers looked at data from the Moon Mineralogy Mapper, an imaging spectrometer that flew aboard India's Chandrayaan-1 lunar orbiter.

The researchers found evidence of water in nearly all of the large pyroclastic deposits that had been previously mapped across the Moon's surface, including deposits near the Apollo 15 and 17 landing sites where the water-bearing glass bead samples were collected.

"The distribution of these water-rich deposits is the key thing," Milliken said. "They're spread across the surface, which tells us that the water found in the Apollo samples isn't a one-off. Lunar pyroclastics seem to be universally water-rich, which suggests the same may be true of the mantle."

The idea that the interior of the Moon is water-rich raises interesting questions about the Moon's formation. Scientists think the Moon formed from debris left behind after an object about the size of Mars slammed into the Earth very early in solar system history. One of the reasons scientists had assumed the Moon's interior should be dry is that it seems unlikely that any of the hydrogen needed to form water could have survived the heat of that impact.

"The growing evidence for water inside the Moon suggest that water did somehow survive, or that it was brought in shortly after the impact by asteroids or comets before the Moon had completely solidified," Li said. "The exact origin of water in the lunar interior is still a big question."

In addition to shedding light on the water story in the early solar system, the research could also have implications for future lunar exploration. The volcanic beads don't contain a lot of water -- about .05 percent by weight, the researchers say -- but the deposits are large, and the water could potentially be extracted.

"Other studies have suggested the presence of water ice in shadowed regions at the lunar poles, but the pyroclastic deposits are at locations that may be easier to access," Li said. "Anything that helps save future lunar explorers from having to bring lots of water from home is a big step forward, and our results suggest a new alternative."

The research was funded by the NASA Lunar Advanced Science and Exploration Research Program (NNX12AO63G).


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Drinking coffee could reduce chance of early death, scientists say

Drinking around three cups of coffee a day has been linked to a lower risk of death “from any cause” in two new large-scale studies.

The habits of coffee-lovers were shown to add years to their life – with high coffee consumption shown to reduce the risk of death from diseases related to circulation and digestion in particular.

While scientists say more research is needed to prove coffee is definitely behind the effects observed in the studies, experts believe the antioxidant plant compounds found in the drink, rather than its caffeine, are responsible for its potentially life-extending effect.

Researchers from Imperial College London and the International Agency for Research on Cancer (IARC) analysed data on the health and coffee-drinking habits of more than half a million people from 10 European countries, including the UK.

They found men who drank at least three cups of coffee a day were 18 per cent less likely to die from any cause than non-coffee drinkers, with women experiencing an eight per cent reduction in mortality over the same period.

Meanwhile, American scientists conducted a separate investigation into the effect of coffee on the health of more than 185,000 participants from different ethnic backgrounds.

People who drank one cup of coffee daily were 12 per cent less likely to die than those who drank no coffee, irrespective of ethnicity, while drinking two to three cups of coffee appeared to reduce the chances of death by 18 per cent.

Experts praised the robust nature of the studies, but warned that further research was needed to prove that the effects observed were caused by the coffee itself, and not other factors.

The US study’s lead author, Dr Veronica Setiawan, from the University of Southern California, said the chemical make-up of the popular beverage was a possible explanation for the findings.

“Coffee contains a lot of antioxidants and phenolic compounds that play an important role in cancer prevention,” she said.

“We cannot say drinking coffee will prolong your life, but we see an association. If you like to drink coffee, drink up! If you’re not a coffee drinker, then you need to consider if you should start.”

Whether the coffee contained caffeine or was decaffeinated did not appear to make a difference in the two studies, both published in the journal Annals of Internal Medicine.

The studies were adjusted for a number of lifestyle factors, such as smoking and diet, to try and isolate and analyse the effects of coffee drinking on health and mortality rates.

Commenting on the research, statistics expert Professor Kevin McConway, from The Open University, said both papers were “well-conducted and large, and show similar results across several different populations and ethnic groups”.

“As a coffee drinker myself, they do reassure me that my habit probably isn’t bad for me,” he said. “However, if I didn’t already drink coffee, I’m not sure that they would persuade me to take it up for the good of my health.  

“That’s because the size of the potential protective effect of coffee, in these studies, is not very large; because we can’t be sure what is causing what; and because, even if coffee drinking is somehow directly improving people’s health on average, neither study throws much light on exactly how it might do that.”

Heart failure is associated with loss of important gut bacteria

In the gut of patients with heart failure, important groups of bacteria are found less frequently and the gut flora is not as diverse as in healthy individuals. Data obtained by scientists of the German Centre for Cardiovascular Research (DZHK) provide valuable points of departure for understanding how gut colonisation is associated with the development and progress of heart failure. It has long been known that heart failure and gut health are linked. The gut, thus, has a worse blood supply in instances of heart failure; the intestinal wall is thicker and more permeable, whereby bacteria and bacterial components may find their way into the blood. Moreover, scientists know that the composition of the gut bacteria is altered in other widespread diseases such as type 2 diabetes. Against this backdrop, researchers at the DZHK site Hamburg/Kiel/Lübeck investigated whether and how the gut flora in patients with heart failure changes.

In order to do this, they analysed the gut bacteria in stool samples of healthy individuals and patients with heart failure. The project headed by Professor Norbert Frey of the University Hospital Schleswig-Holstein, Campus Kiel, was conducted in close cooperation with Professor Andre Franke's team at the Christian-Albrechts-Universität zu Kiel, which found that the sections of the bacterial genome deciphered the distinction of the microorganism. The results showed that a significantly lower proportion of different bacteria are found in the gut in patients with heart failure than in healthy controls. Individual important families of bacteria are significantly reduced. It is still unclear whether the gut flora is altered as a result of heart failure or whether it may be a trigger for this disease.

Influential factors: diet, medication, smoking

"Of course, other factors also affect the composition of our gut bacteria. We know that the gut flora of a vegan who starts eating meat changes within three days," explains associate professor Dr. Mark Lüdde of the University Hospital Schleswig-Holstein, Campus Kiel. For this reason, we asked the Kiel-based researchers of dietary habits beforehand. Individuals with an extreme diet, such as a vegan diet, were not allowed to participate in their study. Instead, they chose individuals with a standard diet comprising both meat and vegetables for both groups.

In addition to diet, medication also affect the gut flora. It was, therefore, important that the control group also took medicinal products that patients with heart failure must take routinely. Antibiotics could not have been administered for at least three months prior. Smokers were also included in both groups. All participants were from the same region and were the same age; gender distribution and BMI were equal in both groups.

Consequence or cause of the disease?

The observed pattern of the reduced genera and families of bacteria seems very characteristic of heart failure, which is why these results may be new points of departure for therapies. The differences between healthy individuals and those with heart failure, thus, came about mainly through the loss of bacteria of the genera Blautia and Collinsella, as well as two previously unknown genera that belong to the families Erysipelotrichaceae and Ruminococcaceae.

Other research projects have shown that the occurrence of Blautia curbs inflammations. Similarly, the genus Faecalibacterium is associated with anti-inflammatory mechanisms. It is, however, not only reduced in patients with heart failure. Since heart failure is accompanied by a chronic inflammation, one theory is that the gut flora fosters the systemic inflammation. Yet generally scientists currently believe that the gut flora changes as a consequence of heart failure. Lüdde and his colleagues believe it is plausible that an altered bacterial profile could also be a risk factor or an early disease marker for heart failure. This is supported by the recent characterisation of trimethylamine N-oxide (TMAO), a metabolic product of gut bacteria, as an independent risk factor for the mortality rate in patients with heart failure. Further investigations are scheduled to clarify the cause and effect of altered gut flora in patients with heart failure. The scientists anticipate obtaining new knowledge on how heart failure occurs and progresses.


Under pressure: Extreme atmosphere stripping may limit exoplanets' habitability

New models of massive stellar eruptions hint at an extra layer of complexity when considering whether an exoplanet may be habitable or not. Models developed for our own Sun have now been applied to cool stars favoured by exoplanet hunters, in research presented by Dr Christina Kay, of the NASA Goddard Flight Center, on Monday 3rd July at the National Astronomy Meeting at the University of Hull.

Coronal mass ejections (CMEs) are huge explosions of plasma and magnetic field that routinely erupt from the Sun and other stars. They are a fundamental factor in so called "space weather," and are already known to potentially disrupt satellites and other electronic equipment on Earth. However, scientists have shown that the effects of space weather may also have a significant impact on the potential habitability of planets around cool, low mass stars -- a popular target in the search for Earth-like exoplanets.

Traditionally an exoplanet is considered "habitable" if its orbit corresponds to a temperature where liquid water can exist. Low mass stars are cooler, and therefore should have habitable zones much closer in to the star than in our own solar system, but their CMEs should be much stronger due to their enhanced magnetic fields.

When a CME impacts a planet, it compresses the planet's magnetosphere, a protective magnetic bubble shielding the planet. Extreme CMEs can exert enough pressure to shrink a magnetosphere so much that it exposes a planet's atmosphere, which can then be swept away from the planet. This could in turn leave the planetary surface and any potential developing lifeforms exposed to harmful X-rays from the nearby host star.

The team built on recent work done at Boston University, taking information about CMEs in our own solar system and applying it to a cool star system.

"We figured that the CMEs would be more powerful and more frequent than solar CMEs, but what was unexpected was where the CMEs ended up" said Christina Kay, who led the research during her PhD work.

The team modelled the trajectory of theoretical CMEs from the cool star V374 Pegasi and found that the strong magnetic fields of the star push most CMEs down to the Astrophysical Current Sheet (ACS), the surface corresponding to the minimum magnetic field strength at each distance, where they remain trapped.

"While these cool stars may be the most abundant, and seem to offer the best prospects for finding life elsewhere, we find that they can be a lot more dangerous to live around due to their CMEs" said Marc Kornbleuth, a graduate student involved in the project.

The results suggest that an exoplanet would need a magnetic field ten to several thousand times that of Earth's to shield their atmosphere from the cool star's CMEs. As many as five impacts a day could occur for planets near the ACS, but the rate decreases to one every other day for planets with an inclined orbit.

Merav Opher, who advised the work, commented, "This work is pioneering in the sense that we are just now starting to explore space weather effects on exoplanets, which will have to be taken into account when discussing the habitability of planets near very active stars."

Vulnerable ‘chokepoints’ threaten global food supply, warns report

Fourteen critical bottlenecks, from roads to ports to shipping lanes, are increasingly at risk from climate change, say analysts.

Increasingly vulnerable “chokepoints” are threatening the security of the global food supply, according to a new report. It identifies 14 critical locations, including the Suez canal, Black Sea ports and Brazil’s road network, almost all of which are already hit by frequent disruptions.

With climate change bringing more incidents of extreme weather, analysts at the Chatham House thinktank warn that the risk of a major disruption is growing but that little is being done to tackle the problem. Food supply interruptions in the past have caused huge spikes in prices which can spark major conflicts.

The chokepoints identified are locations through which exceptional amounts of the global food trade pass. More than half of the globe’s staple crop exports – wheat, maize, rice and soybean – have to travel along inland routes to a small number of key ports in the US, Brazil and the Black Sea. On top of this, more than half of these crops – and more than half of fertilisers – transit through at least one of the maritime chokepoints identified.

“We are talking about a huge share of global supply that could be delayed or stopped for a significant period of time,” said Laura Wellesley, one of the authors of the Chatham House report. “What is concerning is that, with climate change, we are very likely to see one or more of these chokepoint disruptions coincide with a harvest failure, and that’s when things start to get serious.”

The chokepoints are already suffering repeated disruptions, the report found. US inland waterways and railways, which carry 30% of the world’s maize and soy, were hit by flooding that halted traffic in 2016 and a 2012 heatwave that kinked rail lines and caused derailments.

The Panama canal has been hampered by drought, while the Suez canal has been closed by sandstorms and threatened by attempted terrorist bomb attacks. Brazil’s muddy roads are often closed by heavy rain, with 3,000 trucks stranded earlier in 2017, while its vital southern ports have been closed by storms and floods. The only chokepoint that has not recently been disrupted is the Straits of Gibraltar, which connects the Mediterranean with the Atlantic.

The Middle East and North Africa region is particularly vulnerable, the report found, because it has the highest dependency on food imports in the world and is encircled by maritime bottlenecks. It also depends heavily on wheat imports from the Black Sea.

In 2010, a severe heatwave in Russia badly hit the huge grain harvest, leading the government to impose an export ban. As a result, prices spiked in 2011 and this was a significant factor in the Arab Spring conflicts. Other factors were important too, said Wellesley, but she said: “At the start, it was about the price of bread.”

The risks posed by the chokepoints is rising as the international trade in food is growing but also because of global warming, according to the report. It says climate change is bringing more storms, droughts and heatwaves which can block chokepoints and also damage already ageing infrastructure. But it is also likely to fuel armed conflicts, which can also shut down the bottlenecks.

Other countries especially at risk from disruption are poorer nations reliant on imports such as Ethiopia, Kenya, Tanzania and Sudan, as well as richer nations like Japan and South Korea, according to the report.

China is also a major importer but it has done the most to mitigate its exposure to chokepoint risk, the report found. It has diversified its supply routes, for example building a railway across South America to lessen reliance on the Panama canal. Chinese companies also own and operate ports around the world.

The report recommends increased global cooperation to plan for food supply crises and more investment in crucial infrastructure. Wellesley said: “The straits of Hormuz [which Iran has threatened to close] is a really interesting example of where the energy sector is sitting up and taking notice – the food sector should be doing the same. Those same countries that rely on Hormuz to export their oil rely almost entirely on the same strait for their food supply.”

Could humans ever regenerate a heart? A new study suggests the answer is 'yes'

When Mark Martindale decided to trace the evolutionary origin of muscle cells, like the ones that form our hearts, he looked in an unlikely place: the genes of animals without hearts or muscles.

In a new study published in the journal Proceedings of the National Academy of Sciences, the University of Florida scientist and colleagues found genes known to form hearts cells in humans and other animals in the gut of a muscle-less and heartless sea anemone. But the sea anemone isn't just any sea creature. It has superpower-like abilities: Cut it into many pieces and each piece will regenerate into a new animal.

So why does the sea anemone regenerate while humans cannot? When analyzing the function of its "heart genes," study researchers discovered a difference in the way these genes interact with one another, which may help explain its ability to regenerate, said Martindale, a UF biology professor and director of the Whitney Lab for Marine Bioscience in St. Augustine.

The study's findings point to potential for tweaking communication between human genes and advancing our ability to treat heart conditions and stimulate regenerative healing, he said.

"Our study shows that if we learn more about the logic of how genes that give rise to heart cells talk to each other, muscle regeneration in humans might be possible," Martindale said.

These heart genes generate what engineers calls lockdown loops in vertebrates and flies, which means that once the genes are turned on, they tell each other to stay on in an animal's cells for its entire lifetime. In other words, animals with a lockdown on their genes cannot grow new heart parts or use those cells for other functions.

"This ensures that heart cells always stay heart cells and cannot become any other type of cell," Martindale said.

But in sea anemone embryos, the lockdown loops do not exist. This finding suggests a mechanism for why the gut cells expressing heart genes in sea anemones can turn into other kinds of cells, such as those needed to regenerate damaged body parts, Martindale said.

The study supports the idea that definitive muscle cells found in the majority of animals arose from a bifunctional gut tissue that had both absorptive and contractile properties. And while the gut tissue of a sea anemone might not look like a beating heart, it does undergo slow, rhythmic peristaltic waves of contraction, much like the human digestive system.

Study authors argue that the first animal muscle cells might have been very heart-like, Martindale said.

"The idea is these genes have been around a long time and preceded the twitchy muscles that cover our skeleton," Martindale said.

Continued research could one day allow scientists to coax muscles cells into regenerating different kinds of new cells, including more heart cells, Martindale said

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