Observing the ice cap over a period of years, the researchers thought they were seeing a glacial surge, a temporary condition in which snow buildup ebbs and flows over long time scales.

But in this area of the world that is frozen for most of the year, that glacial surge grew faster, wider and fanned out. Having shed nearly 11% of its mass — or 9.5 billion tons of ice since 2013, it may become a more-permanent, impactful ice stream, researchers say.

“This is the first documented case of an ice stream being formed. We really didn’t expect to see this,” said lead author Whyjay Zheng, Cornell University doctoral student. Now, after about six years of study, the stream resembles a triangular-shaped fan, bordered by dark-shaded crevasses. At the wide center channel, the stream ice flows at a relatively high speed — around 3 miles per year.

“In the satellite images, it seems like the entire west wing of the ice cap is just dumping into the sea,” Zheng said. “No one has ever seen this before.”

Until this ice stream discovery, the only other places where geologists had seen ice streams were Antarctica and Greenland.

“This glacier went from doing basically nothing to doing something very unusual — evolving into an ice stream,” said Matthew Pritchard, professor of earth and atmospheric sciences and a fellow at the Cornell Atkinson Center for Sustainability.

Could the stream be a result of climate change? Yes, Pritchard said, as a portion of the surface of the Vavilov ice cap melts each summer. The ice cap can be compared to much larger marine ice sheets that reach the ocean, which can be eroded by warm water and become unstable when supporting ice shelves are lost.

Once the frozen support collapses, the researchers said, ice streams may form, which allows the ice to flow into the ocean in a surprisingly short time.

Pritchard said this ice stream’s relationship to global warming is “hard to ignore,” although researchers are still puzzled by its existence. “The Vavilov ice cap is not a place where warming has hit very hard,” he said. “Yet we’re still seeing this change. It’s a new river of ice we’re trying to understand.”

Zheng points out that mass lost at the Vavilov ice cap is no longer recoverable.

“This is offering scientists another clue as to what happens during global warming. Now once the ice is lost, it is lost,” he said. “Suddenly, we have more water in the oceans.”

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While using the fish to examine cells that normally tell the brain and the rest of the body what’s going on inside the gut after a meal, a team of Duke researchers discovered that a high-fat meal completely shuts down that communication for a few hours.

The cells they were looking at are the enteroendocrine cells, which occur sparsely throughout the lining of the gut, but play a key role in signaling the body about the all-important alimentary canal. In addition to releasing hormones, the cells also have a recently-discovered direct connection to the nervous system and the brain.

These cells produce at least 15 different hormones to send signals to the rest of the body about gut movement, feelings of fullness, digestion, nutrient absorption, insulin sensitivity and energy storage.

“But they fall asleep on the job for a few hours after a high-fat meal, and we don’t yet know if that’s good or bad,” said John Rawls, an associate professor of molecular genetics and microbiology in the Duke School of Medicine.

Since enteroendocrine cells are key players in digestion, the feeling of being full and subsequent feeding behavior, this silencing may be a mechanism that somehow causes people eating a high-fat diet to eat even more.

“This is a previously unappreciated part of the postprandial (after-meal) cycle,” Rawls said. “If this happens every time we eat an unhealthy, high-fat meal, it might cause a change in insulin signaling, which could in turn contribute to the development of insulin resistance and Type 2 diabetes.”

To understand the silencing better, the researchers tried to break the process down step by step in zebrafish.

After they first sense a meal, the enteroendocrine cells trigger a calcium burst within seconds, initiating the signaling process. But after that initial signal there’s a delayed effect later in the after-meal period. It’s during this later response that the silencing occurs, said Rawls, who also directs Duke’s Microbiome Center.

The silenced cells change shape and experience stress in their endoplasmic reticulum, a structure that assembles new proteins. It seems that these enteroendocrine cells, which are specialized to synthesize and secrete proteins like hormones and neurotransmitters, become overstimulated and exhausted for a while.

The team tried the high-fat diet on a line of germ-free zebrafish raised in the absence of any microbes, and found they didn’t experience the same silencing effect. So they began looking for gut microbes that might be involved in the process.

After screening through all the kinds of bacteria found in the gut, they saw that the silencing appeared to be the work of a single type of gut bacteria, called Acinetobacter. These bugs are normally less than 0.1 percent of the total gut microbiome, but they increased 100-fold after a high-fat meal and were the only bacteria able to induce the silencing effect.

“Next we want to understand how Acinetobacter evokes this interesting response,” said Lihua Ye, a postdoctoral fellow and lead author on this paper. “We also suspect other bacteria might also have this capability.”

Rawls said they aren’t sure why silencing occurs, nor whether it has any positive effect on the fish. It might be a way to prevent excessive signaling about the fat, but by being silenced completely like this, the cells won’t be communicating anything else either.

“We don’t understand yet what the long-term impact of enteroendocrine silencing would be on metabolic health,” Rawls said. “This may be a maladaptive response to high-fat feeding that impairs the normal regulatory functions of these cells, leading to metabolic disorders like insulin resistance. But it’s also possible that the silencing is a beneficial adaptation to protect the animal from over-stimulation of the gut cells.”

During excavations on Lolland, archaeologists have found a 5,700-year-old type of “chewing gum” made from birch pitch. In a new study, researchers from the University of Copenhagen succeeded in extracting a complete ancient human genome from the pitch.

It is the first time that an entire ancient human genome has been extracted from anything other than human bones. The new research results have been published in the scientific journal Nature Communications.

‘It is amazing to have gotten a complete ancient human genome from anything other than bone,” says Associate Professor Hannes Schroeder from the Globe Institute, University of Copenhagen, who led the research.

‘What is more, we also retrieved DNA from oral microbes and several important human pathogens, which makes this a very valuable source of ancient DNA, especially for time periods where we have no human remains,’ Hannes Schroeder adds.

Based on the ancient human genome, the researchers could tell that the birch pitch was chewed by a female. She was genetically more closely related to hunter-gatherers from the mainland Europe than to those who lived in central Scandinavia at the time. They also found that she probably had dark skin, dark hair and blue eyes.

Sealed in mud

The birch pitch was found during archaeological excavations at Syltholm, east of Rødbyhavn in southern Denmark. The excavations are being carried out by the Museum Lolland-Falster in connection with the construction of the Fehmarn tunnel.

‘Syltholm is completely unique. Almost everything is sealed in mud, which means that the preservation of organic remains is absolutely phenomenal,’ says Theis Jensen, Postdoc at the Globe Institute, who worked on the study for his PhD and also participated in the excavations at Syltholm.

‘It is the biggest Stone Age site in Denmark and the archaeological finds suggest that the people who occupied the site were heavily exploiting wild resources well into the Neolithic, which is the period when farming and domesticated animals were first introduced into southern Scandinavia,’ Theis Jensen adds.

This is reflected in the DNA results, as the researchers also identified traces of plant and animal DNA in the pitch — specifically hazelnuts and duck — which may have been part of the individual’s diet.

Bacterial evolution

In addition, the researchers succeeded in extracting DNA from several oral microbiota from the pitch, including many commensal species and opportunistic pathogens.

‘The preservation is incredibly good, and we managed to extract many different bacterial species that are characteristic of an oral microbiome. Our ancestors lived in a different environment and had a different lifestyle and diet, and it is therefore interesting to find out how this is reflected in their microbiome,’ says Hannes Schroeder.

The researchers also found DNA that could be assigned to Epstein-Barr Virus, which is known to cause infectious mononucleosis or glandular fever. According to Hannes Schroeder, ancient “chewing gums” bear great potential in researching the composition of our ancestral microbiome and the evolution of important human pathogens.

‘It can help us understand how pathogens have evolved and spread over time, and what makes them particularly virulent in a given environment. At the same time, it may help predict how a pathogen will behave in the future, and how it might be contained or eradicated,’ says Hannes Schroeder.

Chewing gum, all-purpose glue or medicine?

• Birch pitch is a black-brown substance that is produced by heating birch bark. It was commonly used in prehistory for hafting stone tools as an all-purpose glue. The earliest known use of birch pitch dates back to the Palaeolithic.
• Pieces of birch pitch are often found with tooth imprints suggesting that they were chewed. As the pitch solidifies on cooling, it has been suggested that it was chewed to make it malleable again before using it for hafting etc.
• Other uses for birch pitch have also been suggested. For example, one theory suggests that birch pitch could have been used to relieve toothache or other ailments as it is mildly antiseptic. Other theories suggest, people may have used it as a kind of prehistoric tooth brush, to suppress hunger, or just for fun as a chewing gum.

The study, by researchers at Carnegie Mellon University (CMU), Princeton University, and Stanford University, appears in nature sustainability.

“While gas development has boosted aspects of the regional economy, private firms have not faced the full costs of natural gas development,” explains Nicholas Z. Muller, Associate Professor of Economics, Engineering, and Public Policy at CMU’s Tepper School of Business, who coauthored the study. “In our work, we sought to evaluate the cumulative and disparate impacts of current energy systems to inform policymaking.”

Rapid increases in natural gas production in the United States, resulting from advancements in horizontal drilling and hydraulic fracturing (a well-stimulation technique that injects pressurized liquids into a bedrock formation) have dramatically altered world energy markets and the domestic energy outlook. The United States has been the largest natural gas consumer and producer over the past decade, comprising 20 percent of the world market, and the domestic shale gas market has contributed to price volatility and a shift in global flows of natural gas.

In this study, researchers analyzed the shale gas boom and decline in the Appalachian basin, the largest natural gas basin in the United States in terms of reserves and production, from 2004 to 2016. Over this period, volumes of regional shale production increased annually and drilling peaked in 2013. Regional natural gas consumption of electric power and processing volumes also rose. Shale gas production exceeded regional demand, leading to substantial amounts of exports to other parts of the country.

Specifically, the researchers examined premature mortality from fine particulate matter and secondary particulate matter formed from the atmospheric oxidation of nitrogen oxides and volatile organic compound emissions. They also estimated the change in global mean temperature from carbon dioxide and methane emissions, as well as the effects on employment associated with the development of natural gas.

The study estimated that shale gas production degraded air quality, resulting in 1,200 to 4,600 premature deaths (costing $2.3 billion to $61 billion), while boosting employment by 469,000 job years or jobs lasting a year (yielding wage income valued at $8 billion to $33 billion). The authors surmised that these results are in line with the boom-and-bust cycle of shale gas development. But the study also found that natural gas production affected climate (at a cost of from $12 billion to $94 billion, depending on assumptions regarding social costs) in ways that will persist for generations to come, well beyond the period of natural gas activity in the region.

“Our study provides insight on the cumulative socioeconomic and environmental impacts of natural gas systems,” says Jared L. Cohon, former President of CMU, another coauthor. “The argument that natural gas may serve as a bridge fuel is in part premised on its comparative climate advantage over coal and cost advantage over renewables and other energy technologies. However, this is unsupported if natural gas prices do not reflect the actual economics for producing firms or the costs of damages to climate and air quality.”

The study also found that employment effects were concentrated in rural areas where natural gas production occurred, but 76 percent of the cumulative premature mortality due to air pollution was downwind of those areas in urban areas of the United States. The cumulative effects of methane and carbon dioxide emissions on global mean temperature over a 30-year time period were nearly equivalent, but over the long term, the cumulative climate impact was largely due to carbon dioxide, according to the study.

The authors estimated that a tax on production of natural gas of $2 per thousand cubic feet (mcf) of gas would compensate for the cumulative effects of climate and air quality across the supply chain. This is considerably greater than the current fee of $0.08/mcf. The authors were not advocating for such a tax to be implemented absent similiar policies on other energy fuels.

“One of our goals was to assess tradeoffs between different impacts, and comparing physical impacts reveals the implied tradeoffs involved with decisions about natural gas development,” according to Erin N. Mayfield, Postdoctoral Scholar at CMU, who led the study. “Based on our cumulative estimates of premature mortality from air pollution and employment, we concluded that the implied tradeoff is 217 job years per premature mortality at a systems level, or equivalently, three job years per years of life lost.”

Among the study’s limitations, the authors note, are that estimates of the impact of air pollution do not include all impacts associated with this type of pollution, and health impacts from natural gas extend beyond those associated with air pollution and were not considered in the study.