While many of us worry about proteins aggregating in our brains as we age and potentially causing Alzheimer's disease or other types of neurodegeneration, we may not realize that some of the same proteins are aggregating in our muscles, setting us up for muscle atrophy in old age.
University of California, Berkeley, scientists have now found brain cells that help clean up these tangles and prolong life -- at least in worms (Caenorhabditis elegans) and possibly mice. This could lead to drugs that improve muscle health or extend a healthy human lifespan.
The research team's most recent discovery, published Jan. 24 in the journal Science, is that a mere four glial cells in the worm's brain control the stress response in cells throughout its body and increase the worm's lifespan by 75%. That was a surprise, since glial cells are often dismissed as mere support cells for the neurons that do the brain's real work, like learning and memory.
This finding follows a 2013 study in which the UC Berkeley group reported that neurons help regulate the stress response in peripheral cells, though in a different way than glial cells, and lengthen a worm's life by about 25%. In mice, boosting neuronal regulation increases lifespan by about 10%.
Together, these results paint a picture of the brain's two-pronged approach to keeping the body's cells healthy. When the brain senses a stressful environment -- invading bacteria or viruses, for example -- a subset of neurons sends electrical signals to peripheral cells to get them mobilized to respond to the stress, such as through breaking up tangles, boosting protein production and mobilizing stored fat. But because electrical signals produce only a short-lived response, the glial cells kick in to send out a long-lasting hormone, so far unidentified, that maintains a long-term, anti-stress response.
"We have been discovering that if we turn on these responses in the brain, they communicate to the periphery to protect the whole organism from the age onset decline that naturally happens. It rewires their metabolism, it also protects against protein aggregation," said Andrew Dillin, UC Berkeley professor of molecular and cell biology and Howard Hughes Medical Institute (HHMI) investigator. As a result of the new study, "We think that glia are going to be more important than neurons."
While the roundworm C. elegans is a long way evolutionarily from humans, the fact that glial cells seem to have a similar effect in mice suggests that the same may be true of humans. If so, it may lead to drugs that combat muscle wasting and obesity and perhaps increase a healthy lifespan.
"If you look at humans with sarcopenia or at older mice and humans, they have protein aggregates in their muscle," Dillin said. "If we can find this hormone, perhaps it can keep muscle mass higher in older people. There is a huge opportunity here."
In a commentary in the same Jan. 24 issue of Science, two Stanford University scientists, Jason Wayne Miklas and Anne Brunet, echoed that potential. "Understanding how glial cells respond to stress and what neuropeptides they secrete may help identify specific therapeutic interventions to maintain or rebalance these pathways during aging and age-related diseases," they wrote.
How to extend lifespan
Dillin studies the seemingly simultaneous deterioration of cells throughout the body as it ages into death. He has shown in worms and mice that hormones and neurotransmitters released by the brain keep this breakdown in check by activating a stress response in the body's cells and tuning up their metabolism. The response likely originated to fight infection, with the side effect of keeping tissues healthy and extending lifespan. Why our cells stop responding to these signals as we age is the big question.
Over the past decade, he and his colleagues have identified three techniques used by worms to keep their cells healthy and, consequently, longer-lived. Activating the body's heat shock response, for example, protects the cytoplasm of the cell. Stimulating the unfolded protein response protects the cells' energy producing structures, the mitochondria. The unfolded protein response is the cell's way of making sure proteins assume their proper 3D structure, which is crucial for proper functioning inside the cell.
His latest discovery is that glia, as well as neurons, stimulate the unfolded protein response in the endoplasmic reticulum (ER). The ER is the cellular structure that hosts the ribosomes that make proteins -- the ER is estimated to be responsible for the folding and maturation of as many as 13 million proteins per minute.
"A lot of the work we have done has uncovered that certain parts of the brain control the aging of the rest of the animal, in organisms from worms to mice and probably humans," Dillin said.
Two other interventions also increase lifespan in worms: diet restriction, which may call into play other anti-aging mechanisms, and reducing the production of a hormone called insulin-like growth factor (IGF-1).
Dillin's discoveries have already led to new treatments for diseases. He cofounded a company, Mitobridge Inc. (recently acquired by Astellas Pharma Inc.), based on the finding that certain proteins help tune up mitochondria. A drug the company developed is now in phase II clinical trials for treating the damage that occurs when kidneys restart after sudden failure, such as during an operation.
He cofounded another company, Proteostatis Therapeutics, to develop a treatment for cystic fibrosis that is based on activating the unfolded protein response to repair ion channels in people with the disease.
The new discovery about how neurotransmitter and hormones impact the ER could have implications for diseases that involve muscle wasting, such as Huntington's disease and forms of myocytis.
Glial cells
In 2013, Dillin and his colleagues discovered that boosting expression of a protein called xbp-1s in sensory nerve cells in the worm brain boosts the misfolded protein response throughout the worm's body. Shortly afterward, postdoctoral fellow Ashley Frakes decided to see if the glial cells enshrouding these neurons were also involved. When she overexpressed the same protein, xbp-1s, in a subset of these glia (cephalic astrocyte-like sheath glia, or CEPsh), she discovered an even larger effect on peripheral cells, as measured by how they deal with a high-fat diet.
Frakes was able to pinpoint the four CEPsh glia responsible for triggering the ER response, because the C. elegans body is so well studied. There are only 959 cells in the entire worm, 302 of which are nerve cells, and 56 are glial cells.
The CEP neurons and CEPsh glia work differently, but additively, to improve metabolism and clean up protein aggregates as the worms slim down and live twice as long as worms without this protection from a high-fat diet.
"The fact that just a few cells control the entire organism's future is mind-boggling," Dillin said. "Glia work 10 times better than neurons in promoting this response and about twice as good in extending lifespan."
Frakes is currently trying to identify the signaling hormone produced by these glial cells, a first step toward finding a way to activate the response in cells that are declining in function and perhaps to create a drug to tune up human cells and stave off the effects of aging, obesity or other types of stress.
Frakes also found that the worms slimmed down because their fat stores, in the form of lipid droplets, were turned into ER. Another research group in Texas has shown that activating xbp-1s in the neurons of mice also has the effect of reducing fat stores and slimming the mice, protecting them from the effects of a high-fat diet and extending their lifespan.
Read more at Science Daily
Feb 22, 2020
Earthquakes disrupt sperm whales' ability to find food
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| Tail of sperm whale off coast of New Zealand |
The University of Otago-led research is the first to examine the impact of a large earthquake on a population of marine mammals, and offers new insight into how top predators such as sperm whales react and adapt to a large-scale natural disturbance.
Changes in habitat use by a deep-diving predator in response to a coastal earthquake, has recently been published in Deep Sea Research Part I.
Earthquakes and aftershocks can affect sperm whales in several ways, the study explains.
The whales depend on sound for communication, detection of prey and navigation and are also highly sensitive to noise.
Earthquakes produce among the loudest underwater sounds which can induce injuries, hearing damage, displacement and behavioural modifications.
While earthquakes and other extreme natural events are rare occurrences, they can really shift the state of ecosystems by wiping out animals and plants, lead author and Marine Sciences Teaching Fellow Dr Marta Guerra says.
"Understanding how wild populations respond to earthquakes helps us figure out their level of resilience, and whether we need to adjust management of these populations while they are more vulnerable."
The fatal 7.8 magnitude Kaikōura earthquake on November 14, 2016 produced strong ground shaking which triggered widespread underwater mudslides in the underwater canyon off the coastline.
This caused what's known as 'canyon flushing', which in the case of the Kaikōura earthquake, involved high-energy currents flushing 850 tonnes of sediment from the underwater canyon into the ocean.
The Kaikōura canyon is an important year-round foraging ground for sperm whales, which have an important ecological role as top predators and are a key attraction for the local tourism industry -- the main driver of the town's economy.
Just why the canyon is important to sperm whales is "a piece of the puzzle we are still trying to nut out," says Dr Guerra.
"But it's likely related to the immense productivity of the canyon's seabed, and a combination of how the currents interact with the steep topography of the submarine canyon."
Scientists examined data collected on the behaviour of 54 sperm whales between January 2014 and January 2018 -- a timeframe which allowed an opportunity to determine any significant changes in pre and post-earthquake whale foraging behaviour.
"We really didn't know what to expect, as there is so little known about how marine animals react to earthquakes," Dr Guerra says.
The researchers found clear changes in the whales' behaviour in the year following the earthquake: most noticeably whales spent about 25 per cent more time at the surface -- which potentially meant they needed to spend more effort searching for prey, either by diving deeper or for longer times
There are two main reasons the whales may have expanded their search effort, the study explains.
Firstly, benthic invertebrate communities which lived in the upper canyon may have been removed by the canyon flushing event, resulting in sparser prey and reduced foraging abilities.
Secondly, sediment deposition and erosion may have required sperm whales to 're-familiarise' with a modified habitat, increasing the effort to navigate and locate prey whose location may have changed.
"The flushing of almost 40,000 tonnes of biomass from the canyon's seabed probably meant that the animals that normally fed on the seabed had a short supply of food, possibly moving away," Dr Guerra says.
"This would have indirectly affected the prey of sperm whales (deep-water fish and squid), becoming scarce and making it harder for the whales to find food."
Scientists were particularly surprised by how clear the changes were, especially in terms of where the sperm whales were feeding.
"The head of the Kaikōura canyon, where we used to frequently find sperm whales foraging, was quiet as a desert," Dr Guerra says.
Although earthquakes happen relatively frequently in areas where marine mammals live, this study was the first to document the impact on a population, thanks to a long-term monitoring programme which has been in place since 1990.
Globally, there have been punctual observations, such as a fin whale displaying an 'escape response' after an earthquake on the Gulf of California, or particularly low sightings of humpback whales coinciding with the months following an earthquake off Alaska, Dr Guerra says.
"Deep-sea systems are so out of sight that we rarely consider the consequences of them being disturbed, whether by natural of human impacts.
"I think our results emphasise how far-reaching the impacts to the sea bed can be, affecting even animals at the top of the food chain such as sperm whales."
The study found the whales' behavioural changes lasted about a year after the 2016 earthquake and returned to normal levels in the summer of 2017-18.
Read more at Science Daily
Feb 21, 2020
How newborn stars prepare for the birth of planets
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| VANDAM survey: ALMA and the VLA observed more than 300 protostars and their young protoplanetary disks in Orion. This image shows a subset of stars, including a few binaries. The ALMA and VLA data compliment each other: ALMA sees the outer disk structure (visualized in blue), and the VLA observes the inner disks and star cores (orange). |
Most of the stars in the universe are accompanied by planets. These planets are born in rings of dust and gas, called protoplanetary disks. Even very young stars are surrounded by these disks. Astronomers want to know exactly when these disks start to form, and what they look like. But young stars are very faint, and there are dense clouds of dust and gas surrounding them in stellar nurseries. Only highly sensitive radio telescope arrays can spot the tiny disks around these infant stars amidst the densely packed material in these clouds.
For this new research, astronomers pointed both the National Science Foundation's Karl G. Jansky Very Large Array (VLA) and the Atacama Large Millimeter/submillimeter Array (ALMA) to a region in space where many stars are born: the Orion Molecular Clouds. This survey, called VLA/ALMA Nascent Disk and Multiplicity (VANDAM), is the largest survey of young stars and their disks to date.
Very young stars, also called protostars, form in clouds of gas and dust in space. The first step in the formation of a star is when these dense clouds collapse due to gravity. As the cloud collapses, it begins to spin -- forming a flattened disk around the protostar. Material from the disk continues to feed the star and make it grow. Eventually, the left-over material in the disk is expected to form planets.
Many aspects about these first stages of star formation, and how the disk forms, are still unclear. But this new survey provides some missing clues as the VLA and ALMA peered through the dense clouds and observed hundreds of protostars and their disks in various stages of their formation.
Young planet-forming disks
"This survey revealed the average mass and size of these very young protoplanetary disks," said John Tobin of the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia, and leader of the survey team. "We can now compare them to older disks that have been studied intensively with ALMA as well."
What Tobin and his team found, is that very young disks can be similar in size, but are on average much more massive than older disks. "When a star grows, it eats away more and more material from the disk. This means that younger disks have a lot more raw material from which planets could form. Possibly bigger planets already start to form around very young stars."
Four special protostars
Among hundreds of survey images, four protostars looked different than the rest and caught the scientists' attention. "These newborn stars looked very irregular and blobby," said team member Nicole Karnath of the University of Toledo, Ohio (now at SOFIA Science Center). "We think that they are in one of the earliest stages of star formation and some may not even have formed into protostars yet."
It is special that the scientists found four of these objects. "We rarely find more than one such irregular object in one observation," added Karnath, who used these four infant stars to propose a schematic pathway for the earliest stages of star formation. "We are not entirely sure how old they are, but they are probably younger than ten thousand years."
To be defined as a typical (class 0) protostar, stars should not only have a flattened rotating disk surrounding them, but also an outflow -- spewing away material in opposite directions -- that clears the dense cloud surrounding the stars and makes them optically visible. This outflow is important, because it prevents stars from spinning out of control while they grow. But when exactly these outflows start to happen, is an open question in astronomy.
One of the infant stars in this study, called HOPS 404, has an outflow of only two kilometers (1.2 miles) per second (a typical protostar-outflow of 10-100 km/s or 6-62 miles/s). "It is a big puffy sun that is still gathering a lot of mass, but just started its outflow to lose angular momentum to be able to keep growing," explained Karnath. "This is one of the smallest outflows that we have seen and it supports our theory of what the first step in forming a protostar looks like."
Combining ALMA and VLA
The exquisite resolution and sensitivity provided by both ALMA and the VLA were crucial to understand both the outer and inner regions of protostars and their disks in this survey. While ALMA can examine the dense dusty material around protostars in great detail, the images from the VLA made at longer wavelengths were essential to understand the inner structures of the youngest protostars at scales smaller than our solar system.
"The combined use of ALMA and the VLA has given us the best of both worlds," said Tobin. "Thanks to these telescopes, we start to understand how planet formation begins."
Read more at Science Daily
Earliest interbreeding event between ancient human populations discovered
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| Neanderthal and modern human skulls. |
In 2017, Rogers led a study which found that two lineages of ancient humans, Neanderthals and Denisovans, separated much earlier than previously thought and proposed a bottleneck population size. It caused some controversy -- anthropologists Mafessoni and Prüfer argued that their method for analyzing the DNA produced different results. Rogers agreed, but realized that neither method explained the genetic data very well.
"Both of our methods under discussion were missing something, but what?" asked Rogers, professor of anthropology at the University of Utah.
The new study has solved that puzzle and in doing so, it has documented the earliest known interbreeding event between ancient human populations -- a group known as the "super-archaics" in Eurasia interbred with a Neanderthal-Denisovan ancestor about 700,000 years ago. The event was between two populations that were more distantly related than any other recorded. The authors also proposed a revised timeline for human migration out of Africa and into Eurasia. The method for analyzing ancient DNA provides a new way to look farther back into the human lineage than ever before.
"We've never known about this episode of interbreeding and we've never been able to estimate the size of the super-archaic population," said Rogers, lead author of the study. "We're just shedding light on an interval on human evolutionary history that was previously completely dark."
The paper was published on Feb. 20, 2020, in the journal Science Advances.
Out of Africa and interbreeding
Rogers studied the ways in which mutations are shared among modern Africans and Europeans, and ancient Neanderthals and Denisovans. The pattern of sharing implied five episodes of interbreeding, including one that was previously unknown. The newly discovered episode involves interbreeding over 700,000 years ago between a distantly related "super-archaic" population which separated from all other humans around two million years ago, and the ancestors of Neanderthals and Denisovans.
The super-archaic and Neanderthal-Denisovan ancestor populations were more distantly related than any other pair of human populations previously known to interbreed. For example, modern humans and Neanderthals had been separated for about 750,000 years when they interbred. The super-archaics and Neanderthal-Denisovan ancestors were separated for well over a million years.
"These findings about the timing at which interbreeding happened in the human lineage is telling something about how long it takes for reproductive isolation to evolve," said Rogers.
The authors used other clues in the genomes to estimate when the ancient human populations separated and their effective population size. They estimated the super-archaic separated into its own species about two million years ago. This agrees with human fossil evidence in Eurasia that is 1.85 million years old.
The researchers also proposed there were three waves of human migration into Eurasia. The first was two million years ago when the super-archaics migrated into Eurasia and expanded into a large population. Then 700,000 years ago, Neanderthal-Denisovan ancestors migrated into Eurasia and quickly interbred with the descendants of the super-archaics. Finally, modern humans expanded to Eurasia 50,000 years ago where we know they interbred with other ancient humans, including with the Neanderthals.
Read more at Science Daily
Bumble bees can experience an object using one sense and later recognize it using another
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| Bumble bee |
It is because our brain is able to store information in such a way that it can be retrieved by different senses. This multi-sensory integration allows us to form mental images of the world and underpins our conscious awareness.
It turns out that the ability to recognise objects across different senses is present in the tiny brains of an insect.
Researchers at Queen Mary University of London and Macquarie University in Sydney have published new work in the journal Science showing that bumblebees can also find objects in the dark they've only seen before.
In the light, but barred from touching the objects, bumblebees were trained to find rewarding sugar water in one type of object (cubes or spheres) and bitter quinine solution in the other shape.
When tested in the dark, bees preferred the object that was previously rewarding, spending more time exploring them.
Bumblebees also solved the task the other way around. After bees learned to find a particular shape in the dark, they were tested in the light and again preferred the shape they had learned was rewarding by touch alone.
This ability is called cross-modal recognition and it allows us to perceive a complete picture of the world with rich representations.
Dr Cwyn Solvi is the lead author on the paper who was based at Queen Mary University of London and is now at Macquarie University in Sydney. She said: "The results of our study show that bumblebees don't process their senses as separate channels -- they come together as some sort of unified representation."
Professor Lars Chittka, head of the lab at Queen Mary University of London in which the study was performed, said: "We've long known that bees can remember the shapes of flowers. But a smartphone can recognise your face, for example, and does so without any form of awareness. Our new work indicates that something is going on inside the mind of bees that is wholly different from a machine -- that bees can conjure up mental images of shapes."
Selene Gutierrez Al-Khudhairy, co-author on the paper, and now PhD student at the University of York, said: "This is an amazing feat when you consider the miniscule size of a bee's brain. Future investigations of the neural circuitry underlying this ability in bees may one day help reveal how our own brains imagine the world as we do."
Read more at Science Daily
Origins of immune system mapped, opening doors for new cancer immunotherapies
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| Human thymus illustration |
Published today (20 February) in Science, this human thymus atlas has revealed new cell types and identified signals that tell immature immune cells how to develop into T cells. The atlas could also help scientists understand diseases that affect T cell development such as severe combined immunodeficiency (SCID), and adds to the Human Cell Atlas initiative which is creating a Google map of the entire human body.
The thymus gland is located in the chest and produces T cells, key white blood cells that fight infection and disease. These T cells then leave the thymus to enter the blood and other parts of the body to mature further. T cells seek out and destroy invading bacteria and viruses, and also recognise cancer cells and kill them.
Problems in thymus development causes defective T cell generation. This can result in severe immune deficiencies such as SCID, leaving people susceptible to infections. Alternatively, it can affect T cell regulation resulting in autoimmune diseases such as Type 1 diabetes. While mature T cells have been well studied, the development of the human thymus and T cells within it is not fully understood.
Researchers used single cell technology to isolate and analyse around 200,000 individual cells from the developing thymus, and child and adult thymus tissue. They looked at which genes were active in each individual cell to identify the cells, discovering new cell types, and used those genes as tags to map each cell to its exact location in the thymus.
Dr Jongeun Park, the first author on the study from the Wellcome Sanger Institute, said: "We have produced a first human thymus cell atlas to understand what is happening in the healthy thymus across our lifespan, from development to adulthood, and how it provides the ideal environment to support the formation of T cells. This openly available resource will allow researchers worldwide to understand how the immune system develops to protect our body."
Therapeutic T cells are currently being used in the clinic to treat B-cell lymphoma and leukaemia cancers, however a major drawback to these treatments is creating the right subtype of T cells.
Professor Muzlifah Haniffa, a senior author of the study from Newcastle University and Senior Clinical Fellow at the Wellcome Sanger Institute, said: "With this thymus cell atlas, we are unravelling the cellular signals of the developing thymus, and revealing which genes need to be switched on to convert early immune precursor cells into specific T cells. This is really exciting as in the future, this atlas could be used as a reference map to engineer T cells outside the body with exactly the right properties to attack and kill a specific cancer -- creating tailored treatments for tumours."
Professor Tom Taghon, a senior author of the study from Ghent University, Belgium, said: "We now have a very detailed understanding of how T cells form in healthy tissue. We have been able to identify a similar population of precursor cells in the developing thymus and liver, and we believe that these precursors are important for initiating T cell development in the fetus, and for the establishment of a fully competent thymus organ. This is helping us put jigsaw pieces together to get a bigger picture of how immunity develops."
The thymus is unusual in that it is largest and most active in childhood and shrinks after puberty. The thymus has been called the 'pacemaker of life' and by age 35 has almost disappeared. Understanding how the thymus develops and then withers could cast light on aging and how the immune system changes through life.
Read more at Science Daily
Feb 20, 2020
5200-year-old grains in the eastern Altai Mountains redate trans-Eurasian crop exchange
Most people are familiar with the historical Silk Road, but fewer people realize that the exchange of items, ideas, technology, and human genes through the mountain valleys of Central Asia started almost three millennia before organized trade networks formed. These pre-Silk Road exchange routes played an important role in shaping human cultural developments across Europe and Asia, and facilitated the dispersal of technologies such as horse breeding and metal smelting into East Asia. One of the most impactful effects of this process of ancient cultural dispersal was the westward spread of northeast Asian crops and the eastward spread of southwest Asian crops. However, until the past few years, a lack of archaeobotanical studies in Central Asia left a dearth of data relating to when and how this process occurred.
This new study, led by scientists from the Chinese Academy of Sciences and the Max Planck Institute for the Science of Human History, provides details of recently recovered ancient grains from the far northern regions of Inner Asia. Radiocarbon dating shows that the grains include the oldest examples of wheat and barley ever recovered this far north in Asia, pushing back the dates for early farming in the region by at least a millenium. These are also the earliest domesticated plants reported from the northern half of Central Asia, the core of the ancient exchange corridor. This study pulls together sedimentary pollen and ancient wood charcoal data with archaeobotanical remains from the Tiangtian archaeological site in the Chinese Altai Mountains to reveal how humans cultivated crops at such northern latitudes. This study illustrates how adaptable ancient crop plants were to new ecological constraints and how human cultural practices allowed people to survive in unpredictable environments.
The Northern Dispersal of Cereal Grains
The ancient relatives of wheat and barley plants evolved to grow in the warm and dry climate of the eastern Mediterranean and southwest Asia. However, this study illustrates that ancient peoples were cultivating these grasses over five and a half thousand kilometers to the northeast of where they originally evolved to grow. In this study, Dr. Xinying Zhou and his colleagues integrate paleoenvironmental proxies to determine how extreme the ecology was around the archaeological cave site of Tangtian more than five millennia ago, at the time of its occupation. The site is located high in the Altai Mountains on a cold,dry landscape today; however, the study shows that the ecological setting around the site was slightly warmer and more humid at the time when people lived in and around this cave.
The slightly warmer regional conditions were likely the result of shifting air masses bringing warmer, wetter air from the south. In addition to early farmers using a specific regional climate pocket to grow crops in North Asia, analysis showed that the crops they grew evolved to survive in such northern regions. The results of this study provide scholars with evidence for when certain evolutionary changes in these grasses occurred, including changes in the programed reliance of day length, which signals to the plant when to flower, and a greater resistance to cold climates.
The Trans-Eurasian Exchange and Crop Dispersal
The ancient dispersal of crops across Inner Asia has received a lot of attention from biologists and archaeologists in recent years; as Dr. Spengler, one of the study's lead authors, discusses in his recent book Fruit from the Sands, these ancient exchange routes shaped the course of human history. The mingling of crops originating from opposite ends of Asia resulted in the crop-rotation cycles that fueled demographic growth and led to imperial formation. East Asian millets would become one of the most important crops in ancient Europe and wheat would become one of the most important crops in East Asia by the Han Dynasty. While the long tradition of rice cultivation in East Asia made rice a staple of the Asian kitchen, Chinese cuisine would be unrecognizable without wheat-based food items like steamed buns, dumplings, and noodles. The discovery that these plants dispersed across Eurasia earlier than previously understood will have lasting impacts on the study of cultivation and labor practices in ancient Eurasia, as well as the history cultural contact and shifts in culinary systems throughout time.
These new discoveries provide reason to question these views, and seem to suggest that mixed small-scale human populations made major contributions to world history through migration and cultural and technological exchange. "This study not only presents the earliest dates for domesticated grains in far North Asia," says Professor Xiaoqiang Li, director of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, "it represents the earliest beginning of a trans-Eurasian exchange that would eventually develop into the great Silk Road."
Read more at Science Daily
This new study, led by scientists from the Chinese Academy of Sciences and the Max Planck Institute for the Science of Human History, provides details of recently recovered ancient grains from the far northern regions of Inner Asia. Radiocarbon dating shows that the grains include the oldest examples of wheat and barley ever recovered this far north in Asia, pushing back the dates for early farming in the region by at least a millenium. These are also the earliest domesticated plants reported from the northern half of Central Asia, the core of the ancient exchange corridor. This study pulls together sedimentary pollen and ancient wood charcoal data with archaeobotanical remains from the Tiangtian archaeological site in the Chinese Altai Mountains to reveal how humans cultivated crops at such northern latitudes. This study illustrates how adaptable ancient crop plants were to new ecological constraints and how human cultural practices allowed people to survive in unpredictable environments.
The Northern Dispersal of Cereal Grains
The ancient relatives of wheat and barley plants evolved to grow in the warm and dry climate of the eastern Mediterranean and southwest Asia. However, this study illustrates that ancient peoples were cultivating these grasses over five and a half thousand kilometers to the northeast of where they originally evolved to grow. In this study, Dr. Xinying Zhou and his colleagues integrate paleoenvironmental proxies to determine how extreme the ecology was around the archaeological cave site of Tangtian more than five millennia ago, at the time of its occupation. The site is located high in the Altai Mountains on a cold,dry landscape today; however, the study shows that the ecological setting around the site was slightly warmer and more humid at the time when people lived in and around this cave.
The slightly warmer regional conditions were likely the result of shifting air masses bringing warmer, wetter air from the south. In addition to early farmers using a specific regional climate pocket to grow crops in North Asia, analysis showed that the crops they grew evolved to survive in such northern regions. The results of this study provide scholars with evidence for when certain evolutionary changes in these grasses occurred, including changes in the programed reliance of day length, which signals to the plant when to flower, and a greater resistance to cold climates.
The Trans-Eurasian Exchange and Crop Dispersal
The ancient dispersal of crops across Inner Asia has received a lot of attention from biologists and archaeologists in recent years; as Dr. Spengler, one of the study's lead authors, discusses in his recent book Fruit from the Sands, these ancient exchange routes shaped the course of human history. The mingling of crops originating from opposite ends of Asia resulted in the crop-rotation cycles that fueled demographic growth and led to imperial formation. East Asian millets would become one of the most important crops in ancient Europe and wheat would become one of the most important crops in East Asia by the Han Dynasty. While the long tradition of rice cultivation in East Asia made rice a staple of the Asian kitchen, Chinese cuisine would be unrecognizable without wheat-based food items like steamed buns, dumplings, and noodles. The discovery that these plants dispersed across Eurasia earlier than previously understood will have lasting impacts on the study of cultivation and labor practices in ancient Eurasia, as well as the history cultural contact and shifts in culinary systems throughout time.
These new discoveries provide reason to question these views, and seem to suggest that mixed small-scale human populations made major contributions to world history through migration and cultural and technological exchange. "This study not only presents the earliest dates for domesticated grains in far North Asia," says Professor Xiaoqiang Li, director of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, "it represents the earliest beginning of a trans-Eurasian exchange that would eventually develop into the great Silk Road."
Read more at Science Daily
Dog domestication during ice age
Analysis of Paleolithic-era teeth from a 28,500-year-old fossil site in the Czech Republic provides supporting evidence for two groups of canids -- one dog-like and the other wolf-like -- with differing diets, which is consistent with the early domestication of dogs.
The study, published in the Journal of Archaeological Science, was co-directed by Peter Ungar, Distinguished Professor of anthropology at the University of Arkansas.
The researchers performed dental microwear texture analysis on a sample of fossils from the Předmostí site, which contains both wolf-like and dog-like canids. Canids are simply mammals of the dog family. The researchers identified distinctive microwear patterns for each canid morphotype. Compared to the wolf-like canids, the teeth of the early dog canids -- called "protodogs" by the researchers -- had larger wear scars, indicating a diet that included hard, brittle foods. The teeth of the wolf-like canids had smaller scars, suggesting they consumed more flesh, likely from mammoth, as shown by previous research.
This greater durophagy -- animal eating behavior suggesting the consumption of hard objects -- among the dog-like canids means they likely consumed bones and other less desirable food scraps within human settlement areas, Ungar said. It provides supporting evidence that there were two types of canids at the site, each with a distinct diet, which is consistent with other evidence of early-stage domestication.
"Our primary goal was to test whether these two morphotypes expressed notable differences in behavior, based on wear patterns," said Ungar. "Dental microwear is a behavioral signal that can appear generations before morphological changes are established in a population, and it shows great promise in using the archaeological record to distinguish protodogs from wolves."
Dog domestication is the earliest example of animal husbandry and the only type of domestication that occurred well before the earliest definitive evidence of agriculture. However, there is robust scientific debate about the timing and circumstances of the initial domestication of dogs, with estimates varying between 15,000 and 40,000 years ago, well into the Ice Age, when people had a hunter-gatherer way of life. There is also debate about why wolves were first domesticated to become dogs. From an anthropological perspective, the timing of the domestication process is important for understanding early cognition, behavior and the ecology of early Homo sapiens.
From Science Daily
The study, published in the Journal of Archaeological Science, was co-directed by Peter Ungar, Distinguished Professor of anthropology at the University of Arkansas.
The researchers performed dental microwear texture analysis on a sample of fossils from the Předmostí site, which contains both wolf-like and dog-like canids. Canids are simply mammals of the dog family. The researchers identified distinctive microwear patterns for each canid morphotype. Compared to the wolf-like canids, the teeth of the early dog canids -- called "protodogs" by the researchers -- had larger wear scars, indicating a diet that included hard, brittle foods. The teeth of the wolf-like canids had smaller scars, suggesting they consumed more flesh, likely from mammoth, as shown by previous research.
This greater durophagy -- animal eating behavior suggesting the consumption of hard objects -- among the dog-like canids means they likely consumed bones and other less desirable food scraps within human settlement areas, Ungar said. It provides supporting evidence that there were two types of canids at the site, each with a distinct diet, which is consistent with other evidence of early-stage domestication.
"Our primary goal was to test whether these two morphotypes expressed notable differences in behavior, based on wear patterns," said Ungar. "Dental microwear is a behavioral signal that can appear generations before morphological changes are established in a population, and it shows great promise in using the archaeological record to distinguish protodogs from wolves."
Dog domestication is the earliest example of animal husbandry and the only type of domestication that occurred well before the earliest definitive evidence of agriculture. However, there is robust scientific debate about the timing and circumstances of the initial domestication of dogs, with estimates varying between 15,000 and 40,000 years ago, well into the Ice Age, when people had a hunter-gatherer way of life. There is also debate about why wolves were first domesticated to become dogs. From an anthropological perspective, the timing of the domestication process is important for understanding early cognition, behavior and the ecology of early Homo sapiens.
From Science Daily
Earth formed much faster than previously thought, new study shows
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| Illustration of protoplanetary disk |
On an astronomical scale, this is extremely fast, the researchers explain.
If you compare the solar system's estimated 4.6 billion years of existence with a 24-hour period, the new results indicate that the proto-Earth formed in what corresponds to about a minute and a half.
Thus, the results from StarPlan break with the traditional theory that the proto-Earth formed by random collisions between larger and larger planetary bodies throughout several tens of millions of years -- equivalent to about 5-15 minutes out of the above-mentioned fictional 24 hours of formation.
Instead, the new results support a more recent, alternative theory about the formation of planets through the accretion of cosmic dust. The study's lead author, Associate Professor Martin Schiller, explains it as follows:
"The other idea is that we start from dust, essentially. Millimetre-sized objects, all coming together, raining down on the growing body and making the planet in one go," he says, adding:
"Not only is this implication of the rapid formation of the Earth interesting for our solar system. It is also interesting to assess how likely it is for planets to form somewhere else in the galaxy."
The bulk composition of the solar system
The key to the new finding came in the form of the most precise measurements of iron isotopes that have so far been published scientifically.
By studying the isotopic mixture of the metallic element in different meteorites, the researchers found only one type of meteoritic material with a composition similar to Earth: The so-called CI chondrites.
The researchers behind the study describe the dust in this fragile type of meteorite as our best equivalent to the bulk composition of the solar system itself. It was dust like this combined with gas that was funnelled via a circumstellar accretion disk onto the growing Sun.
This process lasted about five million years and our planets were made from material in this disk. Now, the researchers estimate that the proto-Earth's ferrous core also formed already during this period, removing early accreted iron from the mantle.
Two different iron compositions
Other meteorites, for example from Mars, tell us that at the beginning the iron isotopic composition of material contributing to the growing Earth was different. Most likely due to thermal processing of dust close to the young sun, the researchers from StarPlan explain.
After our solar system's first few hundred thousands of years it became cold enough for unprocessed CI dust from further out in the system to enter the accretion region of the proto-Earth.
"This added CI dust overprinted the iron composition in the Earth's mantle, which is only possible if most of the previous iron was already removed into the core. That is why the core formation must have happened early," Martin Schiller explains.
"If the Earth's formation was a random process where you just smashed bodies together, you would never be able to compare the iron composition of the Earth to only one type of meteorite. You would get a mixture of everything," he adds.
More planets, more water, perhaps more life
Based on the evidence for the theory that planets form through the accretion of cosmic dust, the researchers believe that the same process may occur elsewhere in the universe.
This means that also other planets may likely form much faster than if they grow solely from random collisions between objects in space.
Read more at Science Daily
Methane emitted by humans vastly underestimated
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| Methane molecules illustration |
University of Rochester researchers Benjamin Hmiel, a postdoctoral associate in the lab of Vasilii Petrenko, a professor of earth and environmental sciences, and their collaborators, measured methane levels in ancient air samples and found that scientists have been vastly underestimating the amount of methane humans are emitting into the atmosphere via fossil fuels. In a paper published in Nature, the researchers indicate that reducing fossil fuel use is a key target in curbing climate change.
"Placing stricter methane emission regulations on the fossil fuel industry will have the potential to reduce future global warming to a larger extent than previously thought," Hmiel says.
Two Types of Methane
Methane is the second largest anthropogenic -- originating from human activity -- contributor to global warming, after carbon dioxide. But, compared to carbon dioxide, as well as other heat-trapping gases, methane has a relatively short shelf-life; it lasts an average of only nine years in the atmosphere, while carbon dioxide, for instance, can persist in the atmosphere for about a century. That makes methane an especially suitable target for curbing emission levels in a short time frame.
"If we stopped emitting all carbon dioxide today, high carbon dioxide levels in the atmosphere would still persist for a long time," Hmiel says. "Methane is important to study because if we make changes to our current methane emissions, it's going to reflect more quickly."
Methane emitted into the atmosphere can be sorted into two categories, based on its signature of carbon-14, a rare radioactive isotope. There is fossil methane, which has been sequestered for millions of years in ancient hydrocarbon deposits and no longer contains carbon-14 because the isotope has decayed; and there is biological methane, which is in contact with plants and wildlife on the planet's surface and does contain carbon-14. Biological methane can be released naturally from sources such as wetlands or via anthropogenic sources such as landfills, rice fields, and livestock. Fossil methane, which is the focus of Hmiel's study, can be emitted via natural geologic seeps or as a result of humans extracting and using fossil fuels including oil, gas, and coal.
Scientists are able to accurately quantify the total amount of methane emitted to the atmosphere each year, but it is difficult to break down this total into its individual components: Which portions originate from fossil sources and which are biological? How much methane is released naturally and how much is released by human activity?
"As a scientific community we've been struggling to understand exactly how much methane we as humans are emitting into the atmosphere," says Petrenko, a coauthor of the study. "We know that the fossil fuel component is one of our biggest component emissions, but it has been challenging to pin that down because in today's atmosphere, the natural and anthropogenic components of the fossil emissions look the same, isotopically."
Turning to the Past
In order to more accurately separate the natural and anthropogenic components, Hmiel and his colleagues turned to the past, by drilling and collecting ice cores from Greenland. The ice core samples act like time capsules: they contain air bubbles with small quantities of ancient air trapped inside. The researchers use a melting chamber to extract the ancient air from the bubbles and then study its chemical composition.
Hmiel's research focused on measuring the composition of air from the early 18th century -- before the start of the Industrial Revolution -- to the present day. Humans did not begin using fossil fuels in significant amounts until the mid-19th century. Measuring emission levels before this time period allows researchers to identify the natural emissions absent the emissions from fossil fuels that are present in today's atmosphere. There is no evidence to suggest natural fossil methane emissions can vary over the course of a few centuries.
By measuring the carbon-14 isotopes in air from more than 200 years ago, the researchers found that almost all of the methane emitted to the atmosphere was biological in nature until about 1870. That's when the fossil component began to rise rapidly. The timing coincides with a sharp increase in the use of fossil fuels.
The levels of naturally released fossil methane are about 10 times lower than previous research reported. Given the total fossil emissions measured in the atmosphere today, Hmiel and his colleagues deduce that the manmade fossil component is higher than expected -- 25-40 percent higher, they found.
Climate Change Implications
The data has important implications for climate research: if anthropogenic methane emissions make up a larger part of the total, reducing emissions from human activities like fossil fuel extraction and use will have a greater impact on curbing future global warming than scientists previously thought.
Read more at Science Daily
Feb 19, 2020
Enigmatic small primate finally caught on film in Taita, Kenya
Good news from the Kenyan Taita Hills: the Taita mountain dwarf galago still survives. This was confirmed by researchers working at the University of Helsinki Taita Research Station.
The tiny nocturnal prosimian, weighing only 100-180 grams, was first reported in 2002, but no sightings had been made since.
The dwarf galagos in the Taita Hills live in relatively cool montane forests at the altitude of 1,400-1,950 metres. They -- as do all the dwarf galago species -- live in small family groups and communicate using several types of calls. Because all dwarf galago species look similar, they are most conveniently identified on the basis of their distinctive calls.
Finding the small nocturnal animal is challenging, as the forest canopy is in places up to 50 metres high. The animals are spotted with a red light not visible to the animal itself.
"The tropical forest is magically beautiful at night, but one is lucky to catch even a glimpse of the tiny creatures," says University of Helsinki PhD student Hanna Rosti who has spent hours observing and recording the animals.
"Dwarf galagos make agile jumps from tree to tree and feed on moths, cicadas and other insects. I have seen them hunting above ground-dwelling safari ants, where they obviously take advantage of insects fleeing from the voracious ants."
Unfortunately, the tiny mammal seems to be at the verge of extinction.
"The future of Taita mountain dwarf galagos and other endemic animal and plant species depends on the future of native montane forests of the Taita Hills. The conservation status of the forests must be strengthened and their area should be expanded by planting native trees in areas destroyed by cutting and fire. This will protect galago habitats and will ensure that the montane forests continue to provide many vital ecosystem services," says Professor Jouko Rikkinen from the University of Helsinki. He has been studying the biota of the Taita Hills since 2009.
Many animals and plants of the local montane forests have evolved in isolation and the number of endemic species is remarkably high. The Taita Hills belong to the Eastern Arc Mountains, which represent a global biodiversity hotspot.
The diversity of the Taita Hills will never stop surprising Professor Petri Pellikka, the director of the Taita Research Station. "The mountains represent a living laboratory, with great possibilities for ground-breaking research and fascinating new findings."
Read more at Science Daily
The tiny nocturnal prosimian, weighing only 100-180 grams, was first reported in 2002, but no sightings had been made since.
The dwarf galagos in the Taita Hills live in relatively cool montane forests at the altitude of 1,400-1,950 metres. They -- as do all the dwarf galago species -- live in small family groups and communicate using several types of calls. Because all dwarf galago species look similar, they are most conveniently identified on the basis of their distinctive calls.
Finding the small nocturnal animal is challenging, as the forest canopy is in places up to 50 metres high. The animals are spotted with a red light not visible to the animal itself.
"The tropical forest is magically beautiful at night, but one is lucky to catch even a glimpse of the tiny creatures," says University of Helsinki PhD student Hanna Rosti who has spent hours observing and recording the animals.
"Dwarf galagos make agile jumps from tree to tree and feed on moths, cicadas and other insects. I have seen them hunting above ground-dwelling safari ants, where they obviously take advantage of insects fleeing from the voracious ants."
Unfortunately, the tiny mammal seems to be at the verge of extinction.
"The future of Taita mountain dwarf galagos and other endemic animal and plant species depends on the future of native montane forests of the Taita Hills. The conservation status of the forests must be strengthened and their area should be expanded by planting native trees in areas destroyed by cutting and fire. This will protect galago habitats and will ensure that the montane forests continue to provide many vital ecosystem services," says Professor Jouko Rikkinen from the University of Helsinki. He has been studying the biota of the Taita Hills since 2009.
Many animals and plants of the local montane forests have evolved in isolation and the number of endemic species is remarkably high. The Taita Hills belong to the Eastern Arc Mountains, which represent a global biodiversity hotspot.
The diversity of the Taita Hills will never stop surprising Professor Petri Pellikka, the director of the Taita Research Station. "The mountains represent a living laboratory, with great possibilities for ground-breaking research and fascinating new findings."
Read more at Science Daily
Scientists pioneer new way to study exoplanets
A team of scientists using the Low Frequency Array (LOFAR) radio telescope in the Netherlands has observed radio waves that carry the distinct signatures of aurorae, caused by the interaction between a star's magnetic field and a planet in orbit around it.
Radio emission from a star-planet interaction has been long predicted, but this is the first time astronomers have been able to detect and decipher these signals. The discovery paves the way for a novel and unique way to probe the environment around exoplanets -- planets that orbit stars in other solar systems -- and to determine their habitability.
Notably, follow-up observations with the HARPS-N telescope in Spain ruled out the alternate possibility that the interacting companion is another star as opposed to an exoplanet.
The work appears in articles in Nature Astronomy and Astrophysical Journal Letters (ApJL).
The breakthrough centered on red dwarfs, which are the most abundant type of star in our Milky Way -- but much smaller and cooler than our own Sun. This means for a planet to be habitable, it has to be significantly closer to its star than the Earth is to the Sun.
Red dwarfs also have much stronger magnetic fields than the Sun, which means that a habitable planet around a red dwarf is exposed to intense magnetic activity. This can heat the planet and even erode its atmosphere. The radio emissions associated with this process are one of the only tools available to probe the interaction between such planets and their stars.
"The motion of the planet through a red dwarf's strong magnetic field acts like an electric engine much in the same way a bicycle dynamo works," says Harish Vedantham, the lead author of the Nature Astronomy study and a Netherlands Institute for Radio Astronomy (ASTRON) staff scientist. "This generates a huge current that powers aurorae and radio emission on the star."
Thanks to the Sun's weak magnetic field and the larger distance to the planets, similar currents are not generated in the solar system. However, the interaction of Jupiter's moon Io with Jupiter's magnetic field generates a similarly bright radio emission, even outshining the Sun at sufficiently low frequencies.
"We adapted the knowledge from decades of radio observations of Jupiter to the case of this star," says Joe Callingham, ASTRON postdoctoral fellow and co-author of the Nature Astronomy paper. "A scaled-up version of Jupiter-Io has long been predicted to exist in star-planet systems, and the emission we observed fits the theory very well."
To be sure, the astronomers had to rule out an alternate possibility -- that the interacting bodies are two stars in a close binary system instead of a star and its exoplanet. The team searched for the signature of a companion star using the HARPS-N instrument (High Accuracy Radial Velocity Planet Searcher) on the Italian Telescopio Nazionale Galileo on La Palma, Spain.
"Interacting binary stars can also emit radio waves," notes Benjamin Pope, NASA Sagan Fellow at New York University and lead author of the ApJL paper. "Using optical observations to follow up, we searched for evidence of a stellar companion masquerading as an exoplanet in the radio data. We ruled this scenario out very strongly, so we think the most likely possibility is an Earth-sized planet too small to detect with our optical instruments."
The group is now concentrating on finding similar emission from other stars.
"We now know that nearly every red dwarf hosts terrestrial planets, so there must be other stars showing similar emission," observes Callingham, also a co-author of the ApJL paper. "We want to know how this impacts our search for another Earth around another star."
"If we find that most red dwarf planets are blasted by intense stellar winds, this is bad news for their habitability," Pope, part of NYU's Department of Physics and Center for Data Science and a co-author of the Nature Astronomy paper.
The group expects this new method of detecting exoplanets will open up a new way of understanding the habitat of exoplanets.
Read more at Science Daily
Radio emission from a star-planet interaction has been long predicted, but this is the first time astronomers have been able to detect and decipher these signals. The discovery paves the way for a novel and unique way to probe the environment around exoplanets -- planets that orbit stars in other solar systems -- and to determine their habitability.
Notably, follow-up observations with the HARPS-N telescope in Spain ruled out the alternate possibility that the interacting companion is another star as opposed to an exoplanet.
The work appears in articles in Nature Astronomy and Astrophysical Journal Letters (ApJL).
The breakthrough centered on red dwarfs, which are the most abundant type of star in our Milky Way -- but much smaller and cooler than our own Sun. This means for a planet to be habitable, it has to be significantly closer to its star than the Earth is to the Sun.
Red dwarfs also have much stronger magnetic fields than the Sun, which means that a habitable planet around a red dwarf is exposed to intense magnetic activity. This can heat the planet and even erode its atmosphere. The radio emissions associated with this process are one of the only tools available to probe the interaction between such planets and their stars.
"The motion of the planet through a red dwarf's strong magnetic field acts like an electric engine much in the same way a bicycle dynamo works," says Harish Vedantham, the lead author of the Nature Astronomy study and a Netherlands Institute for Radio Astronomy (ASTRON) staff scientist. "This generates a huge current that powers aurorae and radio emission on the star."
Thanks to the Sun's weak magnetic field and the larger distance to the planets, similar currents are not generated in the solar system. However, the interaction of Jupiter's moon Io with Jupiter's magnetic field generates a similarly bright radio emission, even outshining the Sun at sufficiently low frequencies.
"We adapted the knowledge from decades of radio observations of Jupiter to the case of this star," says Joe Callingham, ASTRON postdoctoral fellow and co-author of the Nature Astronomy paper. "A scaled-up version of Jupiter-Io has long been predicted to exist in star-planet systems, and the emission we observed fits the theory very well."
To be sure, the astronomers had to rule out an alternate possibility -- that the interacting bodies are two stars in a close binary system instead of a star and its exoplanet. The team searched for the signature of a companion star using the HARPS-N instrument (High Accuracy Radial Velocity Planet Searcher) on the Italian Telescopio Nazionale Galileo on La Palma, Spain.
"Interacting binary stars can also emit radio waves," notes Benjamin Pope, NASA Sagan Fellow at New York University and lead author of the ApJL paper. "Using optical observations to follow up, we searched for evidence of a stellar companion masquerading as an exoplanet in the radio data. We ruled this scenario out very strongly, so we think the most likely possibility is an Earth-sized planet too small to detect with our optical instruments."
The group is now concentrating on finding similar emission from other stars.
"We now know that nearly every red dwarf hosts terrestrial planets, so there must be other stars showing similar emission," observes Callingham, also a co-author of the ApJL paper. "We want to know how this impacts our search for another Earth around another star."
"If we find that most red dwarf planets are blasted by intense stellar winds, this is bad news for their habitability," Pope, part of NYU's Department of Physics and Center for Data Science and a co-author of the Nature Astronomy paper.
The group expects this new method of detecting exoplanets will open up a new way of understanding the habitat of exoplanets.
Read more at Science Daily
Rules of life: From a pond to the beyond
The Cuatro Cienegas Basin, located in Chihuahuan Desert in Mexico, was once a shallow sea that became isolated from the Gulf of Mexico around 43 million years ago.
This basin has an unusual characteristic of being particularly nutrient-poor and harboring a 'lost world' of many below-ground and above-ground aquatic microbes of ancient marine ancestry.
Because of these characteristics, it is an invaluable place for researchers to study and understand how life may have existed on other planets in our solar system.
In a recent study published in the journal eLIFE a team of researchers, including lead author Jordan Okie of Arizona State University's School of Earth and Space Exploration and senior author Jim Elser of the School of Life Sciences, conducted experiments in the Cuatro Cienegas Basin.
Their goal was to shed light on how fundamental features of an organism's genome -- its size, the way it encodes information, and the density of information -- affect its ability to thrive in an extreme environment.
"This area is so poor in nutrients that many of its ecosystems are dominated by microbes and may have similarities to ecosystems from early Earth, as well as to past wetter environments on Mars that may have supported life," says lead author Okie.
For their experiment, researchers conducted field monitoring, sampling, and routine water chemistry for 32 days in a shallow, nutrient-poor pond called Lagunita in the Cuatro Cienegas Basin.
First, they installed mescocosms (miniature ecosystems) that served as a control group and remained separate from the rest of the pond. They then added a fertilizer solution that was rich in nitrogen and phosphorus to increase microbial growth in the pond.
At the end of the experiment, they examined how the community in the pond changed in response to the additional nutrients, focusing on their ability to process biochemical information within their cells.
J. Craig Venter Institute associate professor Christopher Dupont, who is a senior author on the study, stated, "We hypothesized that microorganisms found in oligotrophic (low nutrient) environments would, out of necessity, rely on low-resource strategies for replication of DNA, transcription of RNA, and translation of protein. Conversely, a copiotrophic (high nutrient) environment favors resource-intensive strategies."
Ultimately, they found that indeed a nutrient-enriched community became dominated by species that could process biochemical information at a faster rate whereas the original low-nutrient community harbored species with reduced costs of biochemical information processing.
"This study is unique and powerful because it takes ideas from the ecological study of large organisms and applies them to microbial communities in a whole-ecosystem experiment," says Elser. "By doing so, we were able, perhaps for the first time, to identify and confirm that there are fundamental genome-wide traits associated with systematic microbial responses to ecosystem nutrient status, without regard to the species identity of those microbes."
What this may suggest for life on other planets is that organisms, no matter where they are, have to have information-processing machinery fine-tuned to the key resources around them. In turn, the supply of these resources will depend on the planetary environment.
Read more at Science Daily
This basin has an unusual characteristic of being particularly nutrient-poor and harboring a 'lost world' of many below-ground and above-ground aquatic microbes of ancient marine ancestry.
Because of these characteristics, it is an invaluable place for researchers to study and understand how life may have existed on other planets in our solar system.
In a recent study published in the journal eLIFE a team of researchers, including lead author Jordan Okie of Arizona State University's School of Earth and Space Exploration and senior author Jim Elser of the School of Life Sciences, conducted experiments in the Cuatro Cienegas Basin.
Their goal was to shed light on how fundamental features of an organism's genome -- its size, the way it encodes information, and the density of information -- affect its ability to thrive in an extreme environment.
"This area is so poor in nutrients that many of its ecosystems are dominated by microbes and may have similarities to ecosystems from early Earth, as well as to past wetter environments on Mars that may have supported life," says lead author Okie.
For their experiment, researchers conducted field monitoring, sampling, and routine water chemistry for 32 days in a shallow, nutrient-poor pond called Lagunita in the Cuatro Cienegas Basin.
First, they installed mescocosms (miniature ecosystems) that served as a control group and remained separate from the rest of the pond. They then added a fertilizer solution that was rich in nitrogen and phosphorus to increase microbial growth in the pond.
At the end of the experiment, they examined how the community in the pond changed in response to the additional nutrients, focusing on their ability to process biochemical information within their cells.
J. Craig Venter Institute associate professor Christopher Dupont, who is a senior author on the study, stated, "We hypothesized that microorganisms found in oligotrophic (low nutrient) environments would, out of necessity, rely on low-resource strategies for replication of DNA, transcription of RNA, and translation of protein. Conversely, a copiotrophic (high nutrient) environment favors resource-intensive strategies."
Ultimately, they found that indeed a nutrient-enriched community became dominated by species that could process biochemical information at a faster rate whereas the original low-nutrient community harbored species with reduced costs of biochemical information processing.
"This study is unique and powerful because it takes ideas from the ecological study of large organisms and applies them to microbial communities in a whole-ecosystem experiment," says Elser. "By doing so, we were able, perhaps for the first time, to identify and confirm that there are fundamental genome-wide traits associated with systematic microbial responses to ecosystem nutrient status, without regard to the species identity of those microbes."
What this may suggest for life on other planets is that organisms, no matter where they are, have to have information-processing machinery fine-tuned to the key resources around them. In turn, the supply of these resources will depend on the planetary environment.
Read more at Science Daily
Seeding oceans with iron may not impact climate change
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| Phytoplankton |
To help stem escalating carbon dioxide emissions produced by the burning of fossil fuels, some scientists have proposed seeding the oceans with iron -- an essential ingredient that can stimulate phytoplankton growth. Such "iron fertilization" would cultivate vast new fields of phytoplankton, particularly in areas normally bereft of marine life.
A new MIT study suggests that iron fertilization may not have a significant impact on phytoplankton growth, at least on a global scale.
The researchers studied the interactions between phytoplankton, iron, and other nutrients in the ocean that help phytoplankton grow. Their simulations suggest that on a global scale, marine life has tuned ocean chemistry through these interactions, evolving to maintain a level of ocean iron that supports a delicate balance of nutrients in various regions of the world.
"According to our framework, iron fertilization cannot have a significant overall effect on the amount of carbon in the ocean because the total amount of iron that microbes need is already just right,'' says lead author Jonathan Lauderdale, a research scientist in MIT's Department of Earth, Atmospheric and Planetary Sciences.
The paper's co-authors are Rogier Braakman, Gael Forget, Stephanie Dutkiewicz, and Mick Follows at MIT.
Ligand soup
The iron that phytoplankton depend on to grow comes largely from dust that sweeps over the continents and eventually settles in ocean waters. While huge quantities of iron can be deposited in this way, the majority of this iron quickly sinks, unused, to the seafloor.
"The fundamental problem is, marine microbes require iron to grow, but iron doesn't hang around. Its concentration in the ocean is so miniscule that it's a treasured resource," Lauderdale says.
Hence, scientists have put forth iron fertilization as a way to introduce more iron into the system. But iron availability to phytoplankton is much higher if it is bound up with certain organic compounds that keep iron in the surface ocean and are themselves produced by phytoplankton. These compounds, known as ligands, constitute what Lauderdale describes as a "soup of ingredients" that typically come from organic waste products, dead cells, or siderophores -- molecules that the microbes have evolved to bind specifically with iron.
Not much is known about these iron-trapping ligands at the ecosystem scale, and the team wondered what role the molecules play in regulating the ocean's capacity to promote the growth of phytoplankton and ultimately absorb carbon dioxide.
"People have understood how ligands bind iron, but not what are the emergent properties of such a system at the global scale, and what that means for the biosphere as a whole," Braakman says. "That's what we've tried to model here."
Iron sweet spot
The researchers set out to characterize the interactions between iron, ligands, and macronutrients such as nitrogen and phosphate, and how these interactions affect the global population of phytoplankton and, concurrently, the ocean's capacity to store carbon dioxide.
The team developed a simple three-box model, with each box representing a general ocean environment with a particular balance of iron versus macronutrients. The first box represents remote waters such as the Southern Ocean, which typically have a decent concentration of macronutrients that are upwelled from the deep ocean. They also have a low iron content given their great distance from any continental dust source.
The second box represents the North Atlantic and other waters that have an opposite balance: high in iron because of proximity to dusty continents, and low in macronutrients. The third box is a stand-in for the deep ocean, which is a rich source of macronutrients, such as phosphates and nitrates.
The researchers simulated a general circulation pattern between the three boxes to represent the global currents that connect all the world's oceans: The circulation starts in the North Atlantic and dives down into the deep ocean, then upwells into the Southern Ocean and returns back to the North Atlantic.
The team set relative concentrations of iron and macronutrients in each box, then ran the model to see how phytoplankton growth evolved in each box over 10,000 years. They ran 10,000 simulations, each with different ligand properties.
Out of their simulations, the researchers identified a crucial positive feedback loop between ligands and iron. Oceans with higher concentrations of ligands had also higher concentrations of iron available for phytoplankton to grow and produce more ligands. When microbes have more than enough iron to feast on, they consume as much of the other nutrients they need, such as nitrogen and phosphate, until those nutrients have been completely depleted.
The opposite is true for oceans with low ligand concentrations: These have less iron available for phytoplankton growth, and therefore have very little biological activity in general, leading to less macronutrient consumption.
The researchers also observed in their simulations a narrow range of ligand concentrations that resulted in a sweet spot, where there was just the right amount of ligand to make just enough iron available for phytoplankton growth, while also leaving just the right amount of macronutrients left over to sustain a whole new cycle of growth across all three ocean boxes.
When they compared their simulations to measurements of nutrient, iron, and ligand concentrations taken in the real world, they found their simulated sweet spot range turned out to be the closest match. That is, the world's oceans appear to have just the right amount of ligands, and therefore iron, available to maximize the growth of phytoplankton and optimally consume macronutrients, in a self-reinforcing and self-sustainable balance of resources.
If scientists were to widely fertilize the Southern Ocean or any other iron-depleted waters with iron, the effort would temporarily stimulate phytoplankton to grow and take up all the macronutrients available in that region. But eventually there would be no macronutrients left to circulate to other regions like the North Atlantic, which depends on these macronutrients, along with iron from dust deposits, for phytoplankton growth. The net result would be an eventual decrease in phytoplankton in the North Atlantic and no significant increase in carbon dioxide draw-down globally.
Lauderdale points out there may also be other unintended effects to fertilizing the Southern Ocean with iron.
"We have to consider the whole ocean as this interconnected system," says Lauderdale, who adds that if phytoplankton in the North Atlantic were to plummet, so too would all the marine life on up the food chain that depends on the microscopic organisms.
Read more at Science Daily
Feb 18, 2020
Discovery at 'flower burial' site could unravel mystery of Neanderthal death rites
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| Illustration of primitive man in cave. |
Researchers say the new find offers an unparalleled opportunity to investigate the "mortuary practices" of this lost species using the latest technologies.
Shanidar Cave was excavated in the 1950s, when archaeologist Ralph Solecki uncovered partial remains of ten Neanderthal men, women and children.
Some were clustered together, with clumps of ancient pollen surrounding one of the skeletons. Solecki claimed this showed Neanderthals buried their dead and conducted funerary rites with flowers.
The 'flower burial' captured the public imagination, and prompted a reappraisal of a species that -- prior to Shanidar Cave -- was thought to have been dumb and animalistic.
It also sparked a decades-long controversy over whether evidence from this extraordinary site did actually point to death rituals, or burial of any kind, and if Neanderthals were really capable of such cultural sophistication.
More than 50 years later, a team of researchers have reopened the old Solecki trench to collect new sediment samples, and discovered the crushed skull and torso bones of another Shanidar Neanderthal.
The discovery has been named Shanidar Z by researchers from Cambridge, Birkbeck and Liverpool John Moores universities.
The work was conducted in conjunction with the Kurdistan General Directorate of Antiquities and the Directorate of Antiquities for Soran Province. The find is announced today in a paper published in the journal Antiquity.
"So much research on how Neanderthals treated their dead has to involve returning to finds from sixty or even a hundred years ago, when archaeological techniques were more limited, and that only ever gets you so far," said Dr Emma Pomeroy, from Cambridge's Department of Archaeology, lead author of the new paper.
"To have primary evidence of such quality from this famous Neanderthal site will allow us to use modern technologies to explore everything from ancient DNA to long-held questions about Neanderthal ways of death, and whether they were similar to our own."
Ralph Solecki died last year aged 101, having never managed to conduct further excavations at his most famous site, despite several attempts.
In 2011, the Kurdish Regional Government approached Professor Graeme Barker from Cambridge's McDonald Institute of Archaeology about revisiting Shanidar Cave. With Solecki's enthusiastic support, initial digging began in 2014, but stopped after two days when ISIS got too close. It resumed the following year.
"We thought with luck we'd be able to find the locations where they had found Neanderthals in the 1950s, to see if we could date the surrounding sediments," said Barker. "We didn't expect to find any Neanderthal bones."
In 2016, in one of the deepest parts of the trench, a rib emerged from the wall, followed by a lumbar vertebra, then the bones of a clenched right hand. However, metres of sediment needed carefully digging out before the team could excavate the skeleton.
During 2018-19 they went on to uncover a complete skull, flattened by thousands of years of sediment, and upper body bones almost to the waist -- with the left hand curled under the head like a small cushion.
Early analysis suggests it is over 70,000 years old. While the sex is yet to be determined, the latest Neanderthal discovery has the teeth of a "middle- to older-aged adult."
Shanidar Z has now been brought on loan to the archaeological labs at Cambridge, where it is being conserved and scanned to help build a digital reconstruction, as more layers of silt are removed.
The team is also working on sediment samples from around the new find, looking for signs of climate change in fragments of shell and bone from ancient mice and snails, as well as traces of pollen and charcoal that could offer insight into activities such as cooking and the famous 'flower burial'.
Four of the Neanderthals, including the 'flower burial' and the latest find, formed what researchers describe as a "unique assemblage." It raises the question of whether Neanderthals were returning to the same spot within the cave to inter their dead.
A prominent rock next to the head of Shanidar Z may have been used as a marker for Neanderthals repeatedly depositing their dead, says Pomeroy, although whether time between deaths was weeks, decades or even centuries will be difficult to determine.
"The new excavation suggests that some of these bodies were laid in a channel in the cave floor created by water, which had then been intentionally dug to make it deeper," said Barker. "There is strong early evidence that Shanidar Z was deliberately buried."
CT-scans in Cambridge have revealed the petrous bone -- one of the densest in the body; a wedge at the base of the skull -- to be intact, offering hope of retrieving ancient Neanderthal DNA from the hot, dry region where "interbreeding" most likely took place as humans spilled out of Africa.
Added Pomeroy: "In recent years we have seen increasing evidence that Neanderthals were more sophisticated than previously thought, from cave markings to use of decorative shells and raptor talons.
Read more at Science Daily
Warming, acidic oceans may nearly eliminate coral reef habitats by 2100
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| Coral bleaching. |
Scientists project 70 to 90 percent of coral reefs will disappear over the next 20 years as a result of climate change and pollution. Some groups are attempting to curb this decline by transplanting live corals grown in a lab to dying reefs. They propose new, young corals will boost the reef's recovery and bring it back to a healthy state.
But new research mapping where such restoration efforts would be most successful over the coming decades finds that by 2100, few to zero suitable coral habitats will remain. The preliminary findings suggest sea surface temperature and acidity are the most important factors in determining if a site is suitable for restoration.
"By 2100, it's looking quite grim," said Renee Setter, a biogeographer at the University of Hawaii Manoa who will present the new findings.
The results highlight some of the devastating impacts Earth's warming climate will have on marine life, according to the researchers. Although pollution poses numerous threats to ocean creatures, the new research suggests corals are most at risk from emission-driven changes in their environment.
"Trying to clean up the beaches is great and trying to combat pollution is fantastic. We need to continue those efforts," Setter said. "But at the end of the day, fighting climate change is really what we need to be advocating for in order to protect corals and avoid compounded stressors."
Projecting the future of coral reefs
Coral reefs around the globe face uncertain futures as ocean temperatures continue to climb. Warmer waters stress corals, causing them to release symbiotic algae living inside them. This turns typically vibrant-colored communities of corals white, a process called bleaching. Bleached corals are not dead, but they are at higher risk of dying, and these bleaching events are becoming more common under climate change.
In the new study, Setter and her colleagues mapped what areas of the ocean would be suitable for coral restoration efforts over the coming decades. The researchers simulated ocean environment conditions like sea surface temperature, wave energy, acidity of the water, pollution, and overfishing in areas where corals now exist. To factor in pollution and overfishing, the researchers considered human population density and land cover use to project how much waste would be released into the surrounding waters.
The researchers found most of parts of the ocean where coral reefs exist today won't be suitable habitats for corals by 2045, and the situation worsened as the simulation extended to 2100.
"Honestly, most sites are out," Setter said. The few sites that are viable by 2100 included only small portions of Baja California and the Red Sea, which are not ideal locations for coral reefs because of their proximity to rivers.
Read more at Science Daily
Reproductive genome from the laboratory
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| DNA illustration |
In the field of synthetic biology, researchers investigate so-called "bottom-up" processes, which means the generation of life mimicking systems from inanimate building blocks. One of the most fundamental characteristics of all living organism is the ability to conserve and reproduce itself as distinct entities. However, the artificial "bottom-up" approach to create a system, which is able to replicate itself, is a great experimental challenge. For the first time, scientists have succeeded in overcoming this hurdle and synthesizing such a system.
Hannes Mutschler, head of the research group "Biomimetic Systems" at the Max Planck Institute for Biochemistry, and his team are dedicated to imitate the replication of genomes and protein synthesis with a "bottom-up" approach. Both processes are fundamental for the self-preservation and reproduction of biological systems. The researchers now succeeded in producing an in vitro system, in which both processes could take place simultaneously. "Our system is able to regenerate a significant proportion of its molecular components itself," explains Mutschler.
In order to start this process, the researchers needed a construction manual as well as various molecular "machines" and nutrients. Translated into biological terms, this means the construction manual is DNA, which contains the information to produce proteins. Proteins are often referred to as "molecular machines" because they often act as catalysts, which accelerate biochemical reactions in organisms. The basic building blocks of DNA are the so-called nucleotides. Proteins are made of amino acids.
Modular structure of the construction manual
Specifically, the researchers have optimized an in vitro expression system that synthesizes proteins based on a DNA blueprint. Due to several improvements, the in vitro expression system is now able to synthesize proteins, known as DNA polymerases, very efficiently. These DNA polymerases then replicate the DNA using nucleotides. Kai Libicher, first author of the study, explains: "Unlike previous studies, our system is able to read and copy comparatively long DNA genomes.
The scientists assembled the artificial genomes from up to eleven ring-shaped pieces of DNA. This modular structure enables them to insert or remove certain DNA segments easily. The largest modular genome reproduced by the researchers in the study consists of more than 116,000 base pairs, reaching the genome length of very simply cells.
Regeneration of proteins
Apart from encoding polymerases that are important for DNA replication, the artificial genome contains blueprints for further proteins, such as 30 translation factors originating from the bacterium Escherischia coli. Translation factors are important for the translation of the DNA blueprint into the respective proteins. Thus, they are essential for self-replicating systems, which imitate biochemical processes. In order to show that the new in vitro expression system is not only able to reproduce DNA, but is also able to produce its own translation factors, the researchers used mass spectrometry. With this analytic method, they determined the amount of proteins produced by the system.
Surprisingly, some of the translation factors were even present in larger quantities after the reaction than added before. According to the researchers, this is an important step towards a continuously self-replicating system that mimics biological processes.
Read more at Science Daily
Researchers Were Not Right About Left Brains, Study Suggests
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| Left and right sides of brain illustration. |
The left and right side of our brain are specialized for some cognitive abilities. For example, in humans, language is processed predominantly in the left hemisphere, and the right hand is controlled by the motor cortex in the left hemisphere. The functional lateralization is reflected by morphological asymmetry of the brain. Left and right hemisphere differ subtly in brain anatomy, the distribution of nerve cells, their connectivity and neurochemistry. Asymmetries of outer brain shape are even visible on endocasts. Most humans have a combination of a more projecting left occipital lobe (located in the back of the brain) with a more projecting right frontal lobe. Brain asymmetry is commonly interpreted as crucial for human brain function and cognition because it reflects functional lateralization. However, comparative studies among primates are rare and it is not known which aspects of brain asymmetry are really uniquely human. Based on previously available data, scientists assumed that many aspects of brain asymmetry evolved only recently, after the split between the human lineage from the lineage of our closest living relatives, the chimpanzees.
In a new paper researchers from the Max Planck Institute for Evolutionary Anthropology and the University of Vienna measured the magnitude and pattern of shape asymmetry of endocasts from humans and apes. "Great ape brains are rarely available for study, but we have developed methods to extract brain asymmetry data from skulls, which are easier to access. This made our study possible in the first place," says lead author Simon Neubauer.
The team found that the magnitude of asymmetry was about the same in humans and most great apes. Only chimpanzees were, on average, less asymmetric than humans, gorillas, and orangutans. They also investigated the pattern of asymmetry and could demonstrate that not only humans, but also chimpanzees, gorillas, and orangutans showed the asymmetry pattern previously described as typically human: the left occipital lobe, the right frontal lobe, as well as the right temporal pole and the right cerebellar lobe projecting more relatively to their contralateral parts. "What surprised us even more," says Philipp Mitteroecker, a co-author of the study, "was that humans were least consistent in this asymmetry with a lot of individual variation around the most common pattern." The authors interpret this as a sign of increased functional and developmental modularization of the human brain. For example, the differential projections of the occipital lobe and the cerebellum are less correlated in humans than in great apes. This finding is interesting because the cerebellum in humans underwent dramatic evolutionary changes and it seems that thereby its asymmetry was affected as well.
Read more at Science Daily
Feb 17, 2020
Breakthrough Listen releases 2 petabytes of data from SETI survey of Milky Way
The Breakthrough Listen Initiative today (Friday, Feb. 14) released data from the most comprehensive survey yet of radio emissions from the plane of the Milky Way Galaxy and the region around its central black hole, and it is inviting the public to search the data for signals from intelligent civilizations.
At a media briefing today in Seattle as part of the annual meeting of the American Association for the Advancement of Science (AAAS), Breakthrough Listen principal investigator Andrew Siemion of the University of California, Berkeley, announced the release of nearly 2 petabytes of data, the second data dump from the four-year old search for extraterrestrial intelligence (SETI). A petabyte of radio and optical telescope data was released last June, the largest release of SETI data in the history of the field.
The data, most of it fresh from the telescope prior to detailed study from astronomers, comes from a survey of the radio spectrum between 1 and 12 gigahertz (GHz). About half of the data comes via the Parkes radio telescope in New South Wales, Australia, which, because of its location in the Southern Hemisphere, is perfectly situated and instrumented to scan the entire galactic disk and galactic center. The telescope is part of the Australia Telescope National Facility, owned and managed by the country's national science agency, CSIRO.
The remainder of the data was recorded by the Green Bank Observatory in West Virginia, the world's largest steerable radio dish, and an optical telescope called the Automated Planet Finder, built and operated by UC Berkeley and located at Lick Observatory outside San Jose, California.
"Since Breakthrough Listen's initial data release last year, we have doubled what is available to the public," said Breakthrough Listen's lead system administrator, Matt Lebofsky. "It is our hope that these data sets will reveal something new and interesting, be it other intelligent life in the universe or an as-yet-undiscovered natural astronomical phenomenon."
The National Radio Astronomy Observatory (NRAO) and the privately-funded SETI Institute in Mountain View, California, also announced today an agreement to collaborate on new systems to add SETI capabilities to radio telescopes operated by NRAO. The first project will develop a system to piggyback on the National Science Foundation's Karl G. Jansky Very Large Array (VLA) in New Mexico and provide data to state-of-the-art digital backend equipment built by the SETI Institute.
"The SETI Institute will develop and install an interface on the VLA, permitting unprecedented access to the rich data stream continuously produced by the telescope as it scans the sky," said Siemion, who, in addition to his UC Berkeley position, is the Bernard M. Oliver Chair for SETI at the SETI Institute. "This interface will allow us to conduct a powerful, wide-area SETI survey that will be vastly more complete than any previous such search."
"As the VLA conducts its usual scientific observations, this new system will allow for an additional and important use for the data we're already collecting," said NRAO Director Tony Beasley. "Determining whether we are alone in the universe as technologically capable life is among the most compelling questions in science, and NRAO telescopes can play a major role in answering it."
"For the whole of human history, we had a limited amount of data to search for life beyond Earth. So, all we could do was speculate. Now, as we are getting a lot of data, we can do real science and, with making this data available to general public, so can anyone who wants to know the answer to this deep question," said Yuri Milner, the founder of Breakthrough Listen.
Earth transit zone survey
In releasing the new radio and optical data, Siemion highlighted a new analysis of a small subset of the data: radio emissions from 20 nearby stars that are aligned with the plane of Earth's orbit such that an advanced civilization around those stars could see Earth pass in front of the sun (a "transit" like those focused on by NASA's Kepler space telescope). Conducted by the Green Bank Telescope, the Earth transit zone survey observed in the radio frequency range between 4 and 8 gigahertz, the so-called C-band. The data were then analyzed by former UC Berkeley undergraduate Sofia Sheikh, now a graduate student at Pennsylvania State University, who looked for bright emissions at a single radio wavelength or a narrow band around a single wavelength. She has submitted the paper to the Astrophysical Journal.
"This is a unique geometry," Sheikh said. "It is how we discovered other exoplanets, so it kind of makes sense to extrapolate and say that that might be how other intelligent species find planets, as well. This region has been talked about before, but there has never been a targeted search of that region of the sky."
While Sheikh and her team found no technosignatures of civilization, the analysis and other detailed studies the Breakthrough Listen group has conducted are gradually putting limits on the location and capabilities of advanced civilizations that may exist in our galaxy.
"We didn't find any aliens, but we are setting very rigorous limits on the presence of a technologically capable species, with data for the first time in the part of the radio spectrum between 4 and 8 gigahertz," Siemion said. "These results put another rung on the ladder for the next person who comes along and wants to improve on the experiment."
Sheikh noted that her mentor, Jason Wright at Penn State, estimated that if the world's oceans represented every place and wavelength we could search for intelligent signals, we have, to date, explored only a hot tub's worth of it.
"My search was sensitive enough to see a transmitter basically the same as the strongest transmitters we have on Earth, because I looked at nearby targets on purpose," Sheikh said. "So, we know that there isn't anything as strong as our Arecibo telescope beaming something at us. Even though this is a very small project, we are starting to get at new frequencies and new areas of the sky."
Beacons in the galactic center?
The so-far unanalyzed observations from the galactic disk and galactic center survey were a priority for Breakthrough Listen because of the higher likelihood of observing an artificial signal from that region of dense stars. If artificial transmitters are not common in the galaxy, then searching for a strong transmitter among the billions of stars in the disk of our galaxy is the best strategy, Simeon said.
On the other hand, putting a powerful, intergalactic transmitter in the core of our galaxy, perhaps powered by the 4 million-solar-mass black hole there, might not be beyond the capabilities of a very advanced civilization. Galactic centers may be so-called Schelling points: likely places for civilizations to meet up or place beacons, given that they cannot communicate among themselves to agree on a location.
"The galactic center is the subject of a very specific and concerted campaign with all of our facilities because we are in unanimous agreement that that region is the most interesting part of the Milky Way galaxy," Siemion said. "If an advanced civilization anywhere in the Milky Way wanted to put a beacon somewhere, getting back to the Schelling point idea, the galactic center would be a good place to do it. It is extraordinarily energetic, so one could imagine that if an advanced civilization wanted to harness a lot of energy, they might somehow use the supermassive black hole that is at the center of the Milky Way galaxy."
Visit from an interstellar comet
Breakthrough Listen also released observations of the interstellar comet 2I/Borisov, which had a close encounter with the sun in December and is now on its way out of the solar system. The group had earlier scanned the interstellar rock 'Oumuamua, which passed through the center of our solar system in 2017. Neither exhibited technosignatures.
"If interstellar travel is possible, which we don't know, and if other civilizations are out there, which we don't know, and if they are motivated to build an interstellar probe, then some fraction greater than zero of the objects that are out there are artificial interstellar devices," said Steve Croft, a research astronomer with the Berkeley SETI Research Center and Breakthrough Listen. "Just as we do with our measurements of transmitters on extrasolar planets, we want to put a limit on what that number is."
Regardless of the kind of SETI search, Siemion said, Breakthrough Listen looks for electromagnetic radiation that is consistent with a signal that we know technology produces, or some anticipated signal that technology could produce, and inconsistent with the background noise from natural astrophysical events. This also requires eliminating signals from cellphones, satellites, GPS, internet, Wi-fi and myriad other human sources.
In Sheikh's case, she turned the Green Bank telescope on each star for five minutes, pointed away for another five minutes and repeated that twice more. She then threw out any signal that didn't disappear when the telescope pointed away from the star. Ultimately, she whittled an initial 1 million radio spikes down to a couple hundred, which she was able to eliminate as Earth-based human interference. The last four unexplained signals turned out to be from passing satellites.
Siemion emphasized that the Breakthrough Listen team intends to analyze all the data released to date and to do it systematically and often.
Read more at Science Daily
At a media briefing today in Seattle as part of the annual meeting of the American Association for the Advancement of Science (AAAS), Breakthrough Listen principal investigator Andrew Siemion of the University of California, Berkeley, announced the release of nearly 2 petabytes of data, the second data dump from the four-year old search for extraterrestrial intelligence (SETI). A petabyte of radio and optical telescope data was released last June, the largest release of SETI data in the history of the field.
The data, most of it fresh from the telescope prior to detailed study from astronomers, comes from a survey of the radio spectrum between 1 and 12 gigahertz (GHz). About half of the data comes via the Parkes radio telescope in New South Wales, Australia, which, because of its location in the Southern Hemisphere, is perfectly situated and instrumented to scan the entire galactic disk and galactic center. The telescope is part of the Australia Telescope National Facility, owned and managed by the country's national science agency, CSIRO.
The remainder of the data was recorded by the Green Bank Observatory in West Virginia, the world's largest steerable radio dish, and an optical telescope called the Automated Planet Finder, built and operated by UC Berkeley and located at Lick Observatory outside San Jose, California.
"Since Breakthrough Listen's initial data release last year, we have doubled what is available to the public," said Breakthrough Listen's lead system administrator, Matt Lebofsky. "It is our hope that these data sets will reveal something new and interesting, be it other intelligent life in the universe or an as-yet-undiscovered natural astronomical phenomenon."
The National Radio Astronomy Observatory (NRAO) and the privately-funded SETI Institute in Mountain View, California, also announced today an agreement to collaborate on new systems to add SETI capabilities to radio telescopes operated by NRAO. The first project will develop a system to piggyback on the National Science Foundation's Karl G. Jansky Very Large Array (VLA) in New Mexico and provide data to state-of-the-art digital backend equipment built by the SETI Institute.
"The SETI Institute will develop and install an interface on the VLA, permitting unprecedented access to the rich data stream continuously produced by the telescope as it scans the sky," said Siemion, who, in addition to his UC Berkeley position, is the Bernard M. Oliver Chair for SETI at the SETI Institute. "This interface will allow us to conduct a powerful, wide-area SETI survey that will be vastly more complete than any previous such search."
"As the VLA conducts its usual scientific observations, this new system will allow for an additional and important use for the data we're already collecting," said NRAO Director Tony Beasley. "Determining whether we are alone in the universe as technologically capable life is among the most compelling questions in science, and NRAO telescopes can play a major role in answering it."
"For the whole of human history, we had a limited amount of data to search for life beyond Earth. So, all we could do was speculate. Now, as we are getting a lot of data, we can do real science and, with making this data available to general public, so can anyone who wants to know the answer to this deep question," said Yuri Milner, the founder of Breakthrough Listen.
Earth transit zone survey
In releasing the new radio and optical data, Siemion highlighted a new analysis of a small subset of the data: radio emissions from 20 nearby stars that are aligned with the plane of Earth's orbit such that an advanced civilization around those stars could see Earth pass in front of the sun (a "transit" like those focused on by NASA's Kepler space telescope). Conducted by the Green Bank Telescope, the Earth transit zone survey observed in the radio frequency range between 4 and 8 gigahertz, the so-called C-band. The data were then analyzed by former UC Berkeley undergraduate Sofia Sheikh, now a graduate student at Pennsylvania State University, who looked for bright emissions at a single radio wavelength or a narrow band around a single wavelength. She has submitted the paper to the Astrophysical Journal.
"This is a unique geometry," Sheikh said. "It is how we discovered other exoplanets, so it kind of makes sense to extrapolate and say that that might be how other intelligent species find planets, as well. This region has been talked about before, but there has never been a targeted search of that region of the sky."
While Sheikh and her team found no technosignatures of civilization, the analysis and other detailed studies the Breakthrough Listen group has conducted are gradually putting limits on the location and capabilities of advanced civilizations that may exist in our galaxy.
"We didn't find any aliens, but we are setting very rigorous limits on the presence of a technologically capable species, with data for the first time in the part of the radio spectrum between 4 and 8 gigahertz," Siemion said. "These results put another rung on the ladder for the next person who comes along and wants to improve on the experiment."
Sheikh noted that her mentor, Jason Wright at Penn State, estimated that if the world's oceans represented every place and wavelength we could search for intelligent signals, we have, to date, explored only a hot tub's worth of it.
"My search was sensitive enough to see a transmitter basically the same as the strongest transmitters we have on Earth, because I looked at nearby targets on purpose," Sheikh said. "So, we know that there isn't anything as strong as our Arecibo telescope beaming something at us. Even though this is a very small project, we are starting to get at new frequencies and new areas of the sky."
Beacons in the galactic center?
The so-far unanalyzed observations from the galactic disk and galactic center survey were a priority for Breakthrough Listen because of the higher likelihood of observing an artificial signal from that region of dense stars. If artificial transmitters are not common in the galaxy, then searching for a strong transmitter among the billions of stars in the disk of our galaxy is the best strategy, Simeon said.
On the other hand, putting a powerful, intergalactic transmitter in the core of our galaxy, perhaps powered by the 4 million-solar-mass black hole there, might not be beyond the capabilities of a very advanced civilization. Galactic centers may be so-called Schelling points: likely places for civilizations to meet up or place beacons, given that they cannot communicate among themselves to agree on a location.
"The galactic center is the subject of a very specific and concerted campaign with all of our facilities because we are in unanimous agreement that that region is the most interesting part of the Milky Way galaxy," Siemion said. "If an advanced civilization anywhere in the Milky Way wanted to put a beacon somewhere, getting back to the Schelling point idea, the galactic center would be a good place to do it. It is extraordinarily energetic, so one could imagine that if an advanced civilization wanted to harness a lot of energy, they might somehow use the supermassive black hole that is at the center of the Milky Way galaxy."
Visit from an interstellar comet
Breakthrough Listen also released observations of the interstellar comet 2I/Borisov, which had a close encounter with the sun in December and is now on its way out of the solar system. The group had earlier scanned the interstellar rock 'Oumuamua, which passed through the center of our solar system in 2017. Neither exhibited technosignatures.
"If interstellar travel is possible, which we don't know, and if other civilizations are out there, which we don't know, and if they are motivated to build an interstellar probe, then some fraction greater than zero of the objects that are out there are artificial interstellar devices," said Steve Croft, a research astronomer with the Berkeley SETI Research Center and Breakthrough Listen. "Just as we do with our measurements of transmitters on extrasolar planets, we want to put a limit on what that number is."
Regardless of the kind of SETI search, Siemion said, Breakthrough Listen looks for electromagnetic radiation that is consistent with a signal that we know technology produces, or some anticipated signal that technology could produce, and inconsistent with the background noise from natural astrophysical events. This also requires eliminating signals from cellphones, satellites, GPS, internet, Wi-fi and myriad other human sources.
In Sheikh's case, she turned the Green Bank telescope on each star for five minutes, pointed away for another five minutes and repeated that twice more. She then threw out any signal that didn't disappear when the telescope pointed away from the star. Ultimately, she whittled an initial 1 million radio spikes down to a couple hundred, which she was able to eliminate as Earth-based human interference. The last four unexplained signals turned out to be from passing satellites.
Siemion emphasized that the Breakthrough Listen team intends to analyze all the data released to date and to do it systematically and often.
Read more at Science Daily
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