A Low-Fat, High-Carb Diet Is Actually Bad for Your Health

It’s hard to be a healthy eater. For decades, we’ve been told that fat — especially the saturated fat found in butter, meat, and fried foods — is the worst thing for our hearts. Dietary fat raises cholesterol levels, after all, which in turn raises the risk of getting heart disease or suffering a fatal heart attack. But a number of recent studies have called into question the “fat-equals-heart-attack” hypothesis, potentially upending the traditional notion of what constitutes a healthy diet.

This week, a study published in The Lancet further fueled the controversy by strongly challenging the conventional wisdom that the less fat you eat, the better. By closely tracking the eating habits of more than 135,000 people from 18 countries, researchers found that on a global level, diets higher in fat (35 percent of daily calories) are linked to a 23 percent reduction in the overall risk of death compared to diets that are low in fat (11 percent of daily calories). They also found that a higher-fat diet reduced the risk of stroke — also considered a cardiovascular event — by 18 percent.

“Contrary to popular belief, increased consumption of dietary fats was associated with a lower risk of death,” said lead author Mahshid Dehghan, an investigator at McMaster University’s Population Health Research Institute, in an audio interview posted on The Lancet website. “The association with lower mortality was seen with all major types of fat,” she added, even saturated fat.

The real danger, researchers discovered, is when people replaced dietary fats with large amounts of carbohydrates. According to study data, which included middle and low-income individuals living on five continents, more than half of the world gets 60 percent or more of their daily calories from carbohydrates, and a quarter gets more than 70 percent of their calories from carbs.

While high-fat diets failed to predict mortality, high-carb diets proved to be a killer. Diets where 60 percent or more of the daily calories came from carbs were associated with a 28 percent greater risk of death.

Before you run out and buy a “healthy” dinner of fried chicken and ice cream, it’s important to put the new study into perspective. One of the chief motivations for surveying such a large and diverse population was that most current dietary recommendations are based on Western diets. In general, North Americans and Europeans don’t struggle to eat enough fat. But the push to limit fat intake in the West doesn’t apply to places like China and Africa, where fat intake is low, but carbohydrate consumption is sky high.

"The current focus on promoting low-fat diets ignores the fact that most people's diets in low and middle-income countries are very high in carbohydrates, which seem to be linked to worse health outcomes,” said Dehghan in a statement, emphasizing that dietary recommendations need to be tailored for specific communities. For much of the world’s populations that means cutting back on carbs and beefing up on fats.

Current global dietary guidelines recommend that 55-65 percent of daily calories come from carbohydrates and less than 10 percent should come from saturated fat, but again, those numbers were based on studies performed in North America and Europe. The new global data showed that very low saturated fat intake (less than three percent) was much worse for people than a diet where 13 percent of calories come from saturated fat.

Dehghan and her team recommended a diet that’s 50-55 percent carbs and 35 percent fat, including both saturated and unsaturated fats. The researchers agreed that trans fats, the “hydrogenated” vegetable fats found in some packaged snacks, should be eliminated completely.

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NASA Probe Cassini Enters Last Weeks as Historic Saturn Mission Comes to an End

Saturn and its rings.

It might as well be the mission motto: "Saturn continues to surprise us."

That's what Earl Maize, project manager for the Cassini mission at Saturn, said during a news conference on Aug. 29. He was referring to the fact that the inner ring system where the Cassini probe is spending some of its final weeks doesn't have as much dust as scientists anticipated, and is therefore not as harsh on the spacecraft's instruments. If the mission could last longer — if the probe weren't running out of fuel, that is — Maize said he'd love to have Cassini explore that region longer.

This trend of finding surprising or unexpected physical characteristics — of Saturn and its moons — has characterized Cassini's entire 13-year stint in the Saturnian system, the scientists said, and continues to prove true in the probe's very last weeks. On Sept. 15, Cassini will complete its "Grand Finale" set of maneuvers and crash into Saturn's atmosphere, transmitting data back to Earth right up until the spacecraft breaks apart.

On its current trajectory, Cassini has also taken the first-ever in-situ samples of Saturn's atmosphere, and Linda Spilker, the Cassini project scientist, said those early results suggest that the chemical and dynamic interactions between particles from the planet's rings and the planet's upper atmosphere are "more complex … than we had both anticipated."

That's good news, she said, because "scientists love mysteries, and the Grand Finale is providing mysteries for everyone."

A final tally of some notable numbers from Cassini’s long mission.

Ongoing Mysteries

Cassin began its "Grand Finale" in April, and the first fruits of new science from that curtain call are already sprouting, NASA scientists said during today's news briefing.

For the last few months, Cassini has been looping through Saturn's inner ring system and sampling the top of the planet's atmosphere, which is "like dipping our toe in Saturn's atmosphere, in preparation for the final plunge," Spilker said during the news briefing.

From those initial tastes of Saturn's atmosphere, Cassini scientists are already finding "incredible, intriguing information" about how the material from Saturn's ring system mixes with the upper layers of the planet's atmosphere. On Sept. 15, the probe will plummet to depths of up to 9,300 miles (15,000 kilometers).

"By having in-situ sampling of the atmosphere, we can directly measure things like the hydrogen-to-helium ratio," Spilker said. Both Jupiter and Saturn consist largely of hydrogen and helium, but the ratios of these two elements can help scientists learn about how and when those planets formed, as well as the nature of the solar system at that time.

"We can directly measure composition of… constituents at a very, very low level in the atmosphere — things that would be much harder to see from a distance with remote sensing and spectroscopy," she said.

This image shows Cassini’s last two Grand Finale orbits, followed by a distant flyby of Titan that pushes the spacecraft into Saturn (final half orbit, in orange).

Spilker said scientists also hope that Cassini's plunge will help them understand the nature of Saturn's magnetic field source, the mass of its rings, and the exact length of its day (the time it takes the planet to spin once on its axis).

Getting that data back to Earth before Cassini is destroyed has required a change in the probe's basic data-transmission system, the scientists said. Typically, Cassini stores its data on a hard drive and transmits the information back to Earth much later, but during its final plummet, Cassini will sop up information from the planet and transmit it back to Earth almost immediately. That direct transmission will start about 3 hours before Cassini hits Saturn's atmosphere.

"A 2- to 3-second latency is all we're expecting," Maize said (referring to the time between Cassini collecting data and transmitting it). "So, we will have repurposed Cassini into an atmospheric probe, and we will have it broadcasting data back down to the very last minute."

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The Human Genome May Be Weeding Out Some Unwanted Mutations

A large-scale study of genetic data reveals that harmful genetic mutations are less prevalent in people who live longer, providing evidence that humans continue to evolve.

Evolution is usually associated with long periods of time, such as the millions of years it took for our ancestors to walk on two legs, or for tiny birds to evolve from larger dinosaurs.

A study analyzing the genomes of 210,000 people in the United States and the United Kingdom, however, finds humans are not only still evolving, but also natural selection can occur over just a few decades. The findings were published today in the journal PLOS Biology.

“With the availability of large human data sets, mostly for biomedical purposes, we are now beginning to have the power to look at small changes that happen within a few generations,” said co-author Molly Przeworski, an evolutionary biologist at Columbia University.

Przeworski, lead author Hakhamenesh Mostafavi, and their colleagues made the determinations after analyzing the genomes of 60,000 people of European ancestry genotyped by Kaiser Permanente in California and 150,000 people in Britain genotyped through the UK Biobank.

The researchers tracked the relative rise and fall of specific mutations across the recorded generations to infer which traits are spreading or dwindling. The mutations were associated with 42 common traits, ranging from height to body mass index, which is a weight to height ratio.

To compensate for a lack of elderly individuals genotyped in the Biobank, the researchers used the participants’ parents age at death as a proxy as they looked for the influence of specific mutations on survival.

The scientists found that sets of genetic mutations that predispose people to heart disease, high cholesterol and LDL “bad” cholesterol, obesity, and asthma appeared less often in people who lived longer and whose genes are therefore more likely to be passed down and spread through the population.

In women over 70, the researchers saw a drop in the frequency of the genetic variant ApoE4, which is linked to Alzheimer’s disease. This is consistent with earlier research showing women with one or two copies of the gene tend to die well before those without it.

In middle aged men, the scientists saw a similar drop in the frequency of a mutation in the CHRNA3 gene associated with heavy smoking.

“If no one smokes, this mutation does not have an effect,” Mostafavi explained. “But among smokers, those who carry this mutation tend to smoke more, and consequently are more exposed to the adverse effects of smoking.”

He said the environment in which a person is raised can also influence the impact of genetic variants, which is affecting information on human height trends. In many cultures, people have been gradually growing taller over the decades. Yet, Mostafavi said, “it could be that we are getting taller because of environmental changes, but are getting genetically shorter.”

These changes could be due to factors like better nutrition and improved health care.

Due to the powerful effect of environmental influences, the researchers do not believe people who find out they carry potentially deleterious genetic mutations should avoid having children. Sometimes these individuals and their children are not harmed at all by the genetic variants.

“We have a specific example of this in the CHRNA3 variant, in that in an environment where people don’t smoke, this isn’t an ‘undesirable’ variant at all,” said co-author Joseph Pickrell of Columbia and the New York Genome Center. “It’s basically neutral.”

Natural selection is continuing to weed out these and other genetic mutations. Pickrell said even if men with ApoE4 have just 0.1 percent fewer children on average than men without it, this would be enough for the variant to be removed quickly by natural selection.

On the upside, the researchers found those who are genetically predisposed to delayed puberty and childbearing tend to live longer. A one-year puberty delay lowered the death rate by 3–4 percent in both men and women, while a one-year childbearing delay lowered the death rate by 6 percent in women.

Taken together, the findings on puberty and the timing of first births suggest genetic variants influencing fertility are evolving in at least some US and UK populations and certain beneficial ones are being conserved.

“Our study serves as a proof of concept that it is now becoming possible to directly observe natural selection in contemporary humans with the availability of large data sets,” Mostafavi said.

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Postcard From the North Pole: Assessing Climate Change at the Top of the World

50 Years of Victory is the world’s most powerful icebreaker. Its two nuclear reactors generate 75,000 horsepower.

On the seventh day, the most powerful icebreaker in the world became stuck.

On the bridge, the moment was met by a brief whoop of joy: acknowledgment of the triumph of Mother Nature over invading human forces.

The improbability of the moment stemmed partly from the icebreaker’s sheer might. Powered by two nuclear reactors, the Murmansk-based 50 Let Pobedy — 50 Years of Victory — boasts 75,000 horsepower that, combined with the 40 centimeter thick steel that strengthens its stem, enables it to slice through ice as thick as 2.7 meters without stopping.

In service since 2006, Victory spends the bulk of its working life breaking through the ice of the Northeast Passage, which connects the Barents Sea to the Bering Sea across the top of Russia. The vessel’s task is to open pathways at the head of convoys of cargo and container ships. During the height of summer, however, it is chartered by adventure tour companies to carry paying passengers on voyages to the North Pole, and it was during just such a voyage last month, one day after leaving the North Pole behind and as the vessel closed in on the rarely visited Arctic archipelago of Franz Josef Land, that Victory finally — and briefly — found its progress blocked.

“The ice had been driven against the shore by the wind, and one of the things the icebreaker has to overcome isn’t just the thickness of the ice, not just breaking it while moving forwards, but displacing it. You have to push it to one side to make space for yourself,” explained Colin Souness, a glaciologist with Quark Expeditions, which chartered Victory for three North Pole journeys this summer, and the source of the joyful whoop. “Otherwise, it crushes you from the side, like Endurance was crushed by ice floes. This ship experiences the same pressure, so you have to come up with ways of lessening the friction. When you can’t displace it, when there’s no open water to push it into, you get pinched and grind to a halt.”

There was no danger of the most powerful icebreaker ever built suffering the same fate as the Ernest Shackleton’s legendary vessel, which sank in the Antarctic in 1915. Within minutes Victory had extricated itself and resumed its forward progress. Even so, it was a sign that even a melting Arctic shouldn’t be taken for granted.

“It shouldn’t be too easy,” Souness said by way of explanation of his celebration. “It’s supposed to be a challenge. I think we should all be reminded of that more often than we are.”

The notion of a pair of nuclear reactors powering through Arctic ice might be discomfiting — and the presence in Murmansk of a memorial comprising the bow of the Kursk, the nuclear submarine that sank in 2000, albeit not as a result of its nuclear propulsion, is testament to the inherent dangers of operating in the unforgiving Arctic environment. But the nuclear fleet’s defenders point to the fact that the country’s first nuclear-powered icebreaker, the Lenin, which is now proudly on display in Murmansk, was built in 1956 and operated without incident, while the Arktika, which carried the first tourists to the North Pole 40 years ago, exceeded its operational expectancy by 10 years.

The ship’s head engineer, Vladimir Yudin, unsurprisingly speaks of his charge with some pride.

“With 500 kilograms of uranium, we have enough fuel for 5 to 6 years,” he said as Victory plowed northward. Two onboard desalination plants produce 200 tons of fresh water per day, more than is consumed even when the standard crew is joined by 100 or more paying passengers.

“Our only limitation is the tiredness of the crew and the capacity of food storage,” he asserted.

And for those who have spent a great deal of time on and around Arctic sea ice, the vessel is certainly impressive.

“It’s kind of remarkable, really, to be on a ship that just slices through ice with barely any trouble at all,” said Geoff York of Polar Bears International, whom Quark invited on board to be a guest lecturer and expert on the North Pole voyage.

But there was another reason, besides the vessel’s sturdiness, why even the briefest of interruptions to the journey came as a surprise. Even as Victory closed in on the North Pole, the sea ice through which it was grinding appeared in shockingly poor condition, even for late summer.

“By 86, 87 degrees latitude north, and even before, we should have expected to be encountering expanses of thick, gnarled, old ice, piled high with pressure ridges,” York said. “And we didn’t. It appeared that there was very little ice that was even second year or older. Most of it seemed to be first-year ice, or worse — no ice at all — and that’s troubling.”

A common sight during 50 Years of Victory’s journey to the North Pole: scattered ice with plenty of open water.

First year ice, as its name implies, is ice that has formed the previous winter and spring. Being newer and thus thinner than older sea ice, it is more vulnerable to melting, so helping to perpetuate a cycle that has been called an Arctic sea ice death spiral.

As ice melts, it reveals open water which, being darker, has a lower albedo level, meaning that instead of reflecting incoming sunlight, it absorbs it. That increases ocean temperatures, leading to greater melting, which in turn causes sea ice not just to retreat but to thin. Thinner ice is more susceptible to melting, and in this way the vicious feedback loop of global warming is radically altering the Arctic region.

While the minimum sea ice extent for 2017 appears on course to become the sixth lowest on record, sea ice volume this year — general considered a better measure for ice loss — appears to be lower than any year except 2012.

“It’s one thing to read the data, to look at the graphs, to see the satellite images,” said York. “But seeing it for yourself really brings home the extent of the change.”

York and PBI Executive Director Krista Wright, who was also on board, said their organization would be interested in working with Quark to include sea ice specialists on board future voyages to conduct measurements of sea ice thickness and extent. For now, observations, even by experts, remain anecdotal. Yet the extent of change is evident to those who frequent the region, even if they are skeptical about the cause.

Victory’s captain, Dmitriy Lobusov, while having personal doubts about the causes, acknowledged that the sea ice is diminishing.

“I have been working in the area for 30 years, and been doing North Pole voyages for 24 years, and I’ve seen many changes in the ice conditions,” he said. “Now we can hardly see the thick, multiyear ice we used to have two decades ago. As we approach the North Pole, you can see we have many stretches of open water.”

Open water confronted the Victory even when it reached the North Pole on its final commercial voyage of the summer on August 5. As passengers celebrated arriving at 90 degrees North, it took Lobusov several hours of steaming to find sea ice thick enough for him to park the ship and for those on board to climb down onto the ice for a day of celebrating, photography, and even an impromptu game of soccer.

A more substantive sign of the ice’s thickness — or lack thereof — is found in the ship’s log. While the Victory is designed to be able to break through ice 2.7 meters thick, its average speed in such conditions is just 2 knots. On the two days before reaching the North Pole, when sea ice cover was 80 and 90 percent, it averaged 16.8 and 13.5 knots respectively. The majority of the occasions on which it encountered genuinely thick or borderline impenetrable ice was in the vicinity of Franz Josef Land, an Arctic archipelago where currents and coastlines combined to pile up ice and provide it with relative protection from melting.

“The change is really striking,” said Souness. “And it really drives home how quickly the ice responds to even slight changes in temperature. At one degree below freezing, ice is resilient and quite rigid. But as soon as it gets to zero [Celsius], it becomes so much softer, and you can see that with the ease with which the ship was just gliding through it.”

All of which raises a question: If an ecosystem is rapidly changing, is the appropriate response to turn it into a tourist destination? If sea ice is thinning and presumably becoming more fragile, what are the impacts of blasting a 75,000 horsepower nuclear-powered icebreaker through it for three months of the year? The presence of people in such a remote environment has impacts, after all.

“It’s the double-edged sword of ecotourism,” admitted Souness. “You can’t go anywhere without affecting the places you go. But if you don’t bring people to places, if you don’t give them the chance to form a relationship of their own, the place will never be relevant to them. To save somewhere, to manage it for the future, a place has to be relevant.”

“Yeah, you have an impact,” she continued, “but you’re damned if you do, damned if you don’t. You have to bring people, or these places won’t be relevant in their minds.”

Joyful passengers celebrate and pose for photographs on the sea ice near the North Pole.

The counter-argument, of course, is that the number of people who can afford to pay the going rate for a North Pole voyage on board the Victory is a pretty small slice of the global populace. And while there were undoubtedly many on board who truly marveled at the icy expanses, who thrilled at the sight of polar bears and walruses and who pumped York and other lecturers for information and insights about what it all meant, there were also plenty whose goal was to tick another box on a list of travel destinations and who remained impervious to the lessons of what they saw and were told.

“I hate to disagree with you,” said one passenger to PBI’s Wright, “but I think the polar bears will be just fine. They’re very smart.”

Souness said he doesn’t seek to convert passengers.

“Some folks will come up after I give a presentation on sea ice loss and say, ‘I don’t believe it,’” he said. “I had one guy come up to me and say he didn’t understand how humans could be causing climate change. I told him about CO2 emissions and the greenhouse effect, and said, ‘It’s a scientific fact,’ and he said, ‘Well, now you’re just turning me off, using phrases like scientific fact. What am I supposed to do with that?’”

The amount of Arctic tourism remains small, though, and the Association of Arctic Expedition Cruise Operators has established standards for operators and visitors. Authorities in Svalbard, Norway and Franz Josef Land have been diligent in limiting the number of visitors and building trails to limit the impact of those visitors.

Of greater long-term significance for the region is what Victory does for the eight or nine months a year its not ferrying tourists through the thinning ice of the Arctic. Those other months the ship’s crew is leading a growing parade of commercial vessels. A new generation of nuclear-powered icebreakers, which will vastly surpass the power of Victory, is under construction. Those new ships will be tasked not only for leading cargo convoys but to facilitate offshore exploration for oil and gas deposits that are becoming — ironically enough — accessible as Arctic ice thins and retreats.

At the same time, thinning ice means vessels are beginning to operate in the region without icebreakers. The tanker Christophe de Margerie traversed the Northeast Passage last month without assistance.

Victory’s passengers leave a footprint that is like a gentle caress of the Arctic compared to that of container traffic or the oil and gas industry. And while not all will heed the messages imparted by scientists during the journey, they stand on the vanguard of Arctic tourism and may one day serve as the eulogists of the region. They are among the first to have the opportunity to witness a long-inaccessible ecosystem and are among the last to have the chance to do so while it still exists in a form it has taken for millennia.

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Physicists propose new theories of black holes from the very early universe

A black hole captured by a neutron star.

UCLA physicists have proposed new theories for how the universe's first black holes might have formed and the role they might play in the production of heavy elements such as gold, platinum and uranium.

Two papers on their work were published in the journal Physical Review Letters.

A long-standing question in astrophysics is whether the universe's very first black holes came into existence less than a second after the Big Bang or whether they formed only millions of years later during the deaths of the earliest stars.

Alexander Kusenko, a UCLA professor of physics, and Eric Cotner, a UCLA graduate student, developed a compellingly simple new theory suggesting that black holes could have formed very shortly after the Big Bang, long before stars began to shine. Astronomers have previously suggested that these so-called primordial black holes could account for all or some of the universe's mysterious dark matter and that they might have seeded the formation of supermassive black holes that exist at the centers of galaxies. The new theory proposes that primordial black holes might help create many of the heavier elements found in nature.

The researchers began by considering that a uniform field of energy pervaded the universe shortly after the Big Bang. Scientists expect that such fields existed in the distant past. After the universe rapidly expanded, this energy field would have separated into clumps. Gravity would cause these clumps to attract one another and merge together. The UCLA researchers proposed that some small fraction of these growing clumps became dense enough to become black holes.

Their hypothesis is fairly generic, Kusenko said, and it doesn't rely on what he called the "unlikely coincidences" that underpin other theories explaining primordial black holes.

The paper suggests that it's possible to search for these primordial black holes using astronomical observations. One method involves measuring the very tiny changes in a star's brightness that result from the gravitational effects of a primordial black hole passing between Earth and that star. Earlier this year, U.S. and Japanese astronomers published a paper on their discovery of one star in a nearby galaxy that brightened and dimmed precisely as if a primordial black hole was passing in front of it.

In a separate study, Kusenko, Volodymyr Takhistov, a UCLA postdoctoral researcher, and George Fuller, a professor at UC San Diego, proposed that primordial black holes might play an important role in the formation of heavy elements such as gold, silver, platinum and uranium, which could be ongoing in our galaxy and others.

The origin of those heavy elements has long been a mystery to researchers.

"Scientists know that these heavy elements exist, but they're not sure where these elements are being formed," Kusenko said. "This has been really embarrassing."

The UCLA research suggests that a primordial black hole occasionally collides with a neutron star -- the city-sized, spinning remnant of a star that remains after some supernova explosions -- and sinks into its depths.

When that happens, Kusenko said, the primordial black hole consumes the neutron star from the inside, a process that takes about 10,000 years. As the neutron star shrinks, it spins even faster, eventually causing small fragments to detach and fly off. Those fragments of neutron-rich material may be the sites in which neutrons fuse into heavier and heavier elements, Kusenko said.

However, the probability of a neutron star capturing a black hole is rather low, said Kusenko, which is consistent with observations of only some galaxies being enriched in heavy elements. The theory that primordial black holes collide with neutron stars to create heavy elements also explains the observed lack of neutron stars in the center of the Milky Way galaxy, a long-standing mystery in astrophysics.

Read more at Science Daily

Face value: Brain's ability to recognize faces is shaped through repeated exposure, study suggests

How does our brain learn to recognize faces?

Scientists have long deemed the ability to recognize faces innate for people and other primates -- something our brains just know how to do immediately from birth.

However, the findings of a new Harvard Medical School study published Sept. 4 in the journal Nature Neuroscience cast doubt on this longstanding view.

Working with macaques temporarily deprived of seeing faces while growing up, a Harvard Medical School team led by neurobiologists Margaret Livingstone, Michael Arcaro, and Peter Schade has found that regions of the brain that are key to facial recognition form only through experience and are absent in primates who don't encounter faces while growing up.

The finding, the researchers say, sheds light on a range of neuro-developmental conditions, including those in which people can't distinguish between different faces or autism, marked by aversion to looking at faces. Most importantly, however, the study underscores the critical formative role of early experiences on normal sensory and cognitive development, the scientists say.

Livingstone, the Takeda Professor of Neurobiology at Harvard Medical School, explains that macaques -- a close evolutionary relative to humans, and a model system for studying human brain development -- form clusters of neurons responsible for recognizing faces in an area of the brain called the superior temporal sulcus by 200 days of age. The relative location of these brain regions, or patches, are similar across primate species.

That knowledge, combined with the fact that infants seem to preferentially track faces early in development, led to the longstanding belief that facial recognition must be inborn, she said. However, both humans and primates also develop areas in the brain that respond to visual stimuli they haven't encountered for as long during evolution, including buildings and text. The latter observation puts a serious wrench in the theory that facial recognition is inborn.

To better understand the basis for facial recognition, Livingstone, along with postdoctoral fellow Arcaro and research assistant Schade, raised two groups of macaques. The first one, the control group, had a typical upbringing, spending time in early infancy with their mothers and then with other juvenile macaques, as well as with human handlers. The other group grew up raised by humans who bottle-fed them, played with and cuddled them -- all while the humans wore welding masks. For the first year of their lives, the macaques never saw a face -- human or otherwise. At the end of the trial, all macaques were put in social groups with fellow macaques and allowed to see both human and primate faces.

When both groups of macaques were 200 days old, the researchers used functional MRI to look at brain images measuring the presence of facial recognition patches and other specialized areas, such as those responsible for recognizing hands, objects, scenes and bodies.

The macaques who had typical upbringing had consistent "recognition" areas in their brains for each of these categories. Those who'd grown up never seeing faces had developed areas of the brain associated with all categories except faces.

Next, the researchers showed both groups images of humans or primates. As expected, the control group preferentially gazed at the faces in those images. In contrast, the macaques raised without facial exposure looked preferentially at the hands. The hand domain in their brains, Livingstone said, was disproportionally large compared to the other domains.

The findings suggest that sensory deprivation has a selective effect on the way the brain wires itself. The brain seems to become very good at recognizing things that an individual sees often, Livingstone said, and poor at recognizing things that it never or rarely sees.

"What you look at is what you end up 'installing' in the brain's machinery to be able to recognize," she added.

Read more at Science Daily

Reindeer grazing protects tundra plant diversity in a warming climate

Reindeer grazing in tundra climate.

Climate warming reduces the number of plant species in the tundra, but plant-eating animals, such as reindeer and voles, can turn this negative effect into something positive. The results of a study coordinated from Umeå University in Sweden are now published in Nature Communications.

"By eating tall and wide-leaved plants, reindeer can increase light availability and thus allow more plant species to co-exist and benefit from warmer conditions," says Elina Kaarlejärvi, post-doctoral researcher at Umeå University, who led the study.

Earlier studies suggest that tundra plant diversity will decrease in response to a warmer climate. However, it is important to know whether the response depends on the abundance of grazing animals, particularly reindeer, voles and lemmings, which are very common in tundra ecosystems. Researchers at Umeå University in Sweden, and Oulu University in Finland, tested this through experimental warming of vegetation on tundra meadows with and without reindeer and voles.

"We found that the warming increased the number of species in plots that were grazed, because it enabled small tundra plants to appear and grow there. But when we fenced reindeer, voles and lemmings out, vegetation became denser and the light was limited. As a result, many small and slowly-growing plant species were lost," says Elina Kaarlejärvi.

The researchers investigated what species appeared and disappeared from the study plots over the course of five years. By doing so, they could test what kinds of species were most affected by warming and grazing. The newly published results suggest that mammalian herbivores could generally help protect diversity in warmer climates by preventing losses of small and slowly-growing species.

The study was performed in Kilpisjärvi in northwest Finland, where the research team tested the importance of grazing animals, warming and nutrient availability by combining small greenhouses that increased the summer temperature by 1-2 degrees Celsius, small fences that excluded reindeer, voles and lemmings, as well as by use of fertilization.

From Science Daily

Bacteria act as aphrodisiac for the closest relatives of animals

A mating swarm of the marine choanoflagellate S. rosetta, triggered by the bacterium V. fischeri. Tubulin is labeled gold, highlighting the cell body and flagellum, while the protein actin is labeled blue, showing off the organism's distinctive collar.

To the surprise of scientists, bacteria can act as an aphrodisiac for one-celled marine organisms notable for being the closest living relative of all animals.

This is the first known example of bacteria triggering mating in a eukaryote, a group that includes all plants and animals.

The organisms, protists called choanoflagellates, eat bacteria and serve as a source of food for small ocean animals like krill. Several years ago, the lab of UC Berkeley's Nicole King, a professor of molecular and cell biology and Howard Hughes Medical Institute investigator, discovered that certain bacteria make these one-celled choanoflagellates (a.k.a. choanos) develop into multicellular colonies.

The new discovery, reported Aug. 31 in the journal Cell by King's lab and the lab of Jon Clardy at Harvard Medical School, suggests that choanos "eavesdrop" on bacteria to make sense of their environment and regulate their life history.

The discovery may help reveal how humans and other animals evolved from single-celled organisms over the last 600 million years.

In this case, the bioluminescent marine bacterium Vibrio fischeri triggers the choanoflagellate Salpingoeca rosetta to swarm and mate. Mating is sometimes a response to a changing environment.

"A lot of evolutionary theory favors the idea that mating happens when conditions are stressful, because you need to reshuffle the deck. With sexual reproduction, you will hopefully get a new combination of gene alleles that is more fit for whatever is coming down the pike," King said.

On the other hand, King discovered five years ago that a different marine bacterium, Algoriphagus machipongonensis, makes S. rosetta form colonies reminiscent of an animal embryo. These multicellular colonies don't involve mating, but could help the organism more efficiently harvest bacterial food from the environment.

"Bacteria are very good at integrating a lot of information about the environment, as different species of bacteria have different nutrient requirements. Choanos may be using bacteria as a proxy for environmental conditions, or live indicators for when its time to get ready for good or bad times," she said.

Though ubiquitous in the oceans, choanoflagellates are relatively mysterious -- one reason that King has focused on them for more than a decade. In 2008, she was part of a team that sequenced the first genome of a choanoflagellate, Monosiga brevicollis, and in 2012 her lab discovered the bacteria that trigger multicellularity.

Mating, however, was a mystery -- even whether choanos engaged in sexual reproduction -- until her team discovered in 2013 that starvation could trigger mating, although only a small percentage of cells would mate. The new study shows that Vibrio bacteria elicit a much more rapid response, with large percentages of cells mating within hours.

"Choanoflagellates have a lot of flexibility in their life history. They can go on and on being asexual, but now we've found that they can also be sexual, and that the switch to sexuality is induced by a bacterial cue within an hour after exposure," says King.

Bacterial aphrodisiacs

The new discovery suggests that other creatures, including some that have been difficult to study in the lab because they fail to mate, may need a little bacterial aphrodisiac to get it on.

"One possibility is that these animals need particular cues from environmental bacteria that are not being provided in the lab," she said.

After UC Berkeley graduate student Arielle Woznica discovered that these bacteria initiated swarming, they collaborated with Clardy's lab to track down the trigger: a protein constantly secreted by the bacteria, which they dubbed EroS.

They showed that EroS is a chondroitinase, an enzyme that degrades a specific type of sulfated molecule found in the extracellular matrix of S. rosetta that was previously thought to be exclusive to animals. They also found that if this enzymatic function was inhibited, swarming did not occur, and that chondroitinases from other aquatic bacteria reproduced the aphrodisiacal effects. As the teams investigate how EroS works, they're continuing to explore the interactions between bacteria and choanoflagellates.

As for implications for animals like humans and their bacterial partners, the so-called microbiome, King said that "we hope that by studying choanos, which are really simple, that we can identify key molecules and then go into the more complex environment of the gut microbiome, for instance, and see whether some of these molecules matter in that context as well."

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Yawning: Why is it so contagious and why should it matter?

Our ability to resist yawning when someone else near us yawns is limited.

Feeling tired? Even if we aren't tired, why do we yawn if someone else does? Experts at the University of Nottingham have published research that suggests the human propensity for contagious yawning is triggered automatically by primitive reflexes in the primary motor cortex -- an area of the brain responsible for motor function.

Their study -- 'A neural basis for contagious yawning' -- has been published in the academic journal Current Biology. It is another stage in their research into the underlying biology of neuropsychiatric disorders and their search for new methods of treatment.

Their latest findings show that our ability to resist yawning when someone else near us yawns is limited. And our urge to yawn is increased if we are instructed to resist yawning. But, no matter how hard we try to stifle a yawn, it might change how we yawn but it won't alter our propensity to yawn. Importantly, they have discovered that the urge to yawn -- our propensity for contagious yawning -- is individual to each one of us.

Stephen Jackson, Professor of Cognitive Neuroscience, in the School of Psychology, led the multidisciplinary study. He said: "We suggest that these findings may be particularly important in understanding further the association between motor excitability and the occurrence of echophenomena in a wide range of clinical conditions that have been linked to increased cortical excitability and/or decreased physiological inhibition such as epilepsy, dementia, autism, and Tourette syndrome."

Echophenomena isn't just a human trait

Contagious yawning is triggered involuntarily when we observe another person yawn -- it is a common form of echophenomena -- the automatic imitation of another's words (echolalia) or actions (echopraxia). And it's not just humans who have a propensity for contagious yawning -- chimpanzees and dogs do it too.

Echophenomena can also be seen in a wide range of clinical conditions linked to increased cortical excitability and/or decreased physiological inhibition such as epilespsy, dementia, autism and Tourette syndrome.

The neural basis for contagious yawning

The neural basis for echophenomena is unknown. To test the link between motor excitability and the neural basis for contagious yawning the Nottingham research team used transcranial magnetic stimulation (TMS). They recruited 36 adults to help with their study. These volunteers viewed video clips showing someone else yawning and were instructed to either resist yawning or to allow themselves to yawn.

The participants were videoed throughout, and their yawns and stifled yawns were counted. In addition, the intensity of each participant's perceived urge to yawn was continuously recorded.

Using electrical stimulation they were also able to increase the urge to yawn.

Georgina Jackson, Professor of Cognitive Neuropsychology in the Institute of Mental Health, said: "This research has shown that the 'urge' is increased by trying to stop yourself. Using electrical stimulation we were able to increase excitability and in doing so increase the propensity for contagious yawning. In Tourettes if we could reduce the excitability we might reduce the tics and that's what we are working on."

The search for personalised treatments

TMS was used to quantify motor cortical excitability and physiological inhibition for each participant and predict the propensity for contagious yawning across all the volunteers.

The TMS measures proved to be significant predictors of contagious yawning and demonstrated that each individuals's propensity for contagious yawning is determined by cortical excitability and physiological inhibiton of the primary motor cortext.

The research has been funded by ESRC doctoral training award to Beverley J Brown and is part of Nottingham's new Biomedical Research Centre (BRC) leading research into mental health technology with the aim of using brain imaging techniques to understand how neuro modulation works.

Professor Stephen Jackson said: "If we can understand how alterations in cortical excitability give rise to neural disorders we can potentially reverse them. We are looking for potential non-drug, personalised treatments, using TMS that might be affective in modulating inbalances in the brain networks."

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Scents and social preference: Neuroscientists ID the roots of attraction

A confocal image of a tadpole brain reveals dopaminergic (green) neurons, the type increased in typical kinship recognition, and GABAergic (red) neurons, those elevated in cases of expanded social kinship.

A baby lamb is separated from its family. Somehow, in vast herds of sheep that look virtually identical, the lost youngling locates its kin. Salmon swim out to the vast expanses of the sea and migrate back home to their precise spawning grounds with bewildering accuracy.

Scientists have long known about such animal kinship attachments, some known as "imprinting," but the mechanisms underlying them have been hidden in a black box at the cellular and molecular levels. Now biologists at the University of California San Diego have unlocked key elements of these mysteries, with implications for understanding social attraction and aversion in a range of animals and humans.

Davide Dulcis of UC San Diego's Psychiatry Department at the School of Medicine, Giordano Lippi, Darwin Berg and Nick Spitzer of the Division of Biological Sciences and their colleagues published their results in the August 31, 2017 online issue of the journal Neuron.

In a series of neurobiological studies stretching back eight years, the researchers examined larval frogs (tadpoles), which are known to swim with family members in clusters. Focusing the studies on familial olfactory cues, or kinship odors, the researchers identified the mechanisms by which two- to four-day old tadpoles chose to swim with family members over non-family members. Their tests also revealed that tadpoles that were exposed to early formative odors of those outside of their family cluster were also inclined to swim with the group that generated the smell, expanding their social preference beyond their own true kin.

The researchers discovered that this change is rooted in a process known as "neurotransmitter switching," an area of brain research pioneered by Spitzer and further investigated by Dulcis in the context of psychostimulants and the diseased brain. The dopamine neurotransmitter was found in high levels during normal family kinship bonding, but switched to the GABA neurotransmitter in the case of artificial odor kinship, or "non-kin" attraction.

"In the reversed conditions there is a clear sign of neurotransmitter switching, so now we can see that these neurotransmitters are really controlling a specific behavior," said Dulcis, an associate professor. "You can imagine how important this is for social preference and behavior. We have innate responses in relationships, falling in love and deciding whether we like someone. We use a variety of cues and these odorants can be part of the social preference equation."

The scientists took the study to a deeper level, seeking to find how this mechanism unfolds at the genetic level.

Sequencing helped isolate two key microRNAs, molecules involved in coordinating gene expression. Sifting through hundreds of possibilities they identified microRNA-375 and microRNA-200b as the key regulators mediating the neurotransmitter switching for attraction and aversion, affecting the expression of genes known as Pax6 and Bcl11b that ultimately control the tadpole's swimming behavior.

"MicroRNAs were ideal candidates for the job," said Lippi, a project scientist in Berg's laboratory in the Division's Neurobiology Section. "They are post-transcriptional repressors and can target hundreds of different mRNAs to consolidate specific genetic programs and trigger developmental switches."

The study began in 2009 and deepened in size and scope over the years. Reviewers of the paper were impressed with the project's breadth, including one who commended the authors "for this heroic study which is both fascinating and comprehensive."

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