A newly discovered, naturally low-caffeine tea plant

Leaves and young shoots of a rare wild tea that is low in caffeine.

Tea drinkers who seek the popular beverage's soothing flavor without its explosive caffeine jolt could soon have a new, naturally low-caffeine option. In a study appearing in ACS' Journal of Agricultural and Food Chemistry, scientists report that a recently discovered wild tea plant in China contains little or no caffeine and, unlike many industrially decaffeinated products, could potentially provide many of the health benefits of regular brewed teas.

In 2017, Americans drank nearly 4 billion gallons of tea, according to the Tea Association of the USA. The association estimates that up to 18 percent of those drinks were decaffeinated. To decaffeinate tea, manufacturers often use supercritical carbon dioxide or hot water treatments. However, these methods can affect the brew's flavor and destroy compounds in the tea associated with lowered cholesterol, reduced risk of heart attack or stroke, and other health benefits. Recently, scientists discovered hongyacha (HYC), a rare wild tea found in the mountains of southern China. Local residents believe it can it can cure colds, soothe stomach pain and relieve a host of other ailments. But little is known about its structural makeup or its chemical composition. Liang Chen and colleagues sought to close that gap.

The researchers used high-performance liquid chromatography to analyze HYC buds and leaves collected during the growing season. In addition to finding several potentially health-promoting compounds not found in regular tea, they determined that HYC contains virtually no caffeine. Digging deeper, they found this was because of a mutation in the gene encoding the enzyme tea caffeine synthase, which promotes caffeine production in most tea plants. The researchers conclude that naturally low-caffeine HYC could possibly become a popular drink because of its distinct composition and unique health benefits.

From Science Daily

Replaying the tape of life: Is it possible?

E. coli culture

How predictable is evolution? The answer has long been debated by biologists grappling with the extent to which history affects the repeatability of evolution.

A review published in the Nov. 9 issue of Science explores the complexity of evolution's predictability in extraordinary detail. In it, researchers at Kenyon College, Michigan State University and Washington University in St. Louis closely examine evidence from a number of empirical studies of evolutionary repeatability and contingency in an effort to fully interrogate ideas about contingency's role in evolution.

The question of evolution's predictability was notably raised by the late paleontologist Stephen Jay Gould, who advocated the view that evolution is contingent and unrepeatable in his 1989 book Wonderful Life. "Replay the tape a million times ... and I doubt that anything like Homo sapiens would ever evolve again," Gould mused, noting that being able to "replay the tape" and give history a do-over would be impossible. Yet since the publication of Wonderful Life, many evolutionary biologists have taken up this challenge and conducted their own versions of Gould's experiment, albeit on smaller scales. In doing so, they have reached different conclusions about the interplay between randomness of mutations, chance historical events, and directionality imparted by natural selection.

"How history plays out isn't really predictable. Historical outcomes are contingent on long chains of events loaded with tiny little details. A dropped packet of cigars wrapped with the Confederate army's marching orders was found by a Union soldier, which led to the Battle of Antietam, which led to Lincoln announcing the Emancipation Proclamation. What if those cigars hadn't been dropped, or if they hadn't been found by a Union soldier? Evolution is similar, in that it plays out over vast periods of time with long, unique chains of events involving a lot of chance. Unlike history, though, evolution has the deterministic force of natural selection, but that determinism is always in tension with the chanciness. How does that tension affect what evolves? Which is more important: contingency on details of history, or determinism?" said Zachary Blount, a senior research associate at MSU and visiting assistant professor of biology at Kenyon College who served as lead author of the review.

Blount was joined in his work by Richard Lenski, the Hannah Distinguished Professor of Microbial Ecology at MSU, and Jonathan Losos, the William H. Danforth Distinguished University Professor at Washington University in St. Louis.

"The idea of replaying life's tape -- having a fresh start -- is something almost everyone has thought about at some point in their own lives. It's also something that has long interested biologists, but on the grand scale of the history of life on Earth," Lenski said. "Since Gould introduced the metaphor of replaying life's tape, many studies have tried to characterize the repeatability of evolution. What our review shows is that there's no easy answer: Sometimes evolution produces strikingly similar solutions, and other times evolving lineages take very different paths even under the same circumstances. I think that's part of the fascination and beauty of evolution, that it produces both the expected and unexpected, perhaps like in our individual lives, but on a vastly larger scale."

Gould's thought experiment still stimulates robust debate, in part due to inconsistencies Gould introduced in how he described his replay metaphor, as well as confusion around the concept of contingency. Gould often conflated two common meanings of "contingency": as dependence on something else, and as a chance event.

"There are multiple, different literatures on Gould's idea, and these literatures are not talking to each other," Losos said. "There are microbial evolution studies. There are all the studies of convergent evolution, or lack of convergent evolution. And there's also a philosophical literature on what Gould meant when he said, 'replay the tape.' That is, more generally, when you talk about the role of contingency -- which is the term Gould used -- what does that actually mean?"

Their review of existing empirical studies focused on primarily on three types of "replay studies": laboratory evolution experiments with fast-evolving organisms; experiments carried out in nature; and natural experiments that compare lineages that evolved under similar conditions. The comprehensive analysis revealed a complex picture of evolutionary change in which both contingency and determinism are evident.

Blount, Lenski and Losos examined a number of different types of laboratory experiments, including parallel replay experiments, in which identical populations of an organism are separately evolved under identical conditions, and analytic replay experiments, in which specimens are frozen from a parallel replay experiment and then resurrected and re-evolved from different points in time. This review included study of the long-term evolution experiment with Escherichia coli (LTEE), started by Lenski in 1988. The LTEE has followed 12 populations of E. coli, founded from a single clone, for more than 70,000 generations. Samples of each population were frozen every 500 generations, allowing researchers to directly compare the evolving bacteria with their ancestors.

Blount, Lenski and Losos also examined experiments that attempt to replicate evolution in natural settings. Only a few such experiments exist to date, and their review of these experiments indicated a high degree of repeatability in evolutionary responses to different historical conditions.

Their review of comparative studies of "natural experiments" further illuminated evidence of evolution's predictability. Similar features can independently evolve in multiple species -- for example, anole lizards of the Caribbean, which separately evolved traits such as the length of their legs and tails to ease their life in their specific habitats. Yet convergence in evolution does not always occur, as their review shows; contingency can play a strong role in divergent evolution of various traits.

"What we clearly see is that both convergence and lack of convergence occur a lot in the natural world," Losos said. "It's not useful just to keep adding to the two lists. The real question that people are now turning to is: Why does convergence occur sometimes and not others? That is where research is now headed. That's the question we need to focus on."

Read more at Science Daily

Eye contact reduces lying

A new study from the University of Tampere found that eye contact can make us act more honestly.

In everyday life, we often find ourselves in situations where we suspect that someone is being untruthful, whether it is a child claiming cluelessness about a missing cookie or a colleague arriving late and blaming the traffic. When asking the other person about the matter, a common intuition is to look them in the eyes. A recent study now suggests that, in situations like these, the use of eye contact may indeed be useful.

Psychologists at the University of Tampere, Finland, investigated the effect of another's direct gaze on lying in an interactive experiment. In the experiment, participants played a lying game on a computer against another person. On each game trial, participants were first briefly presented with a view of the opponent through a smart glass window, after which they made a move in the game. Depending on the trial, the opponent either looked the participant in the eyes or downward toward their computer screen. The opponent's direct gaze was found to reduce subsequent lying in the game.

The effect of watching eyes on dishonesty has also been previously investigated, but only with the use of eye images. In previous studies, these images have been shown to, for example, reduce taking drinks without paying or stealing bicycles.

"This was the first study to demonstrate the effect by using actual eye contact with another person and by measuring not just any form of dishonesty, but lying," says Jonne Hietanen, the first author of the study.

The results have practical implications for both everyday and professional situations, such as police interrogations.

"However, because the results were obtained in an experimental situation, one must be careful not to draw too far-reaching conclusions," Hietanen emphasizes.

From Science Daily

Amazon forests failing to keep up with climate change

Measuring big trees in Central Amazon, Brazil, 2016

A team of more than 100 scientists has assessed the impact of global warming on thousands of tree species across the Amazon to discover the winners and losers from 30 years of climate change. Their analysis found the effects of climate change are altering the rainforest's composition of tree species but not quickly enough to keep up with the changing environment.

The team, led by University of Leeds in collaboration with more than 30 institutions around the world, used long-term records from more than a hundred plots as part of the Amazon Forest Inventory Network (RAINFOR) to track the lives of individual trees across the Amazon region. Their results found that since the 1980s, the effects of global environmental change -- stronger droughts, increased temperatures and higher levels of carbon dioxide in the atmosphere -- has slowly impacted specific tree species' growth and mortality.

In particular, the study found the most moisture-loving tree species are dying more frequently than other species and those suited to drier climates were unable to replace them.

Lead author Dr Adriane Esquivel Muelbert, from the School of Geography at Leeds, said: "The ecosystem's response is lagging behind the rate of climate change. The data showed us that the droughts that hit the Amazon basin in the last decades had serious consequences for the make-up of the forest, with higher mortality in tree species most vulnerable to droughts and not enough compensatory growth in species better equipped to survive drier conditions."

The team also found that bigger trees -- predominantly canopy species in the upper levels of the forests -- are outcompeting smaller plants. The team's observations confirms the belief that canopy species would be climate change "winners" as they benefit from increased carbon dioxide, which can allow them to grow more quickly. This further suggests that higher carbon dioxide concentrations also have a direct impact on rainforest composition and forest dynamics -- the way forests grow, die and change.

In addition, the study shows that pioneer trees -- trees that quickly spring up and grow in gaps left behind when trees die -- are benefiting from the acceleration of forest dynamics.

Study co-author Oliver Phillips, Professor of Tropical Ecology at Leeds and founder of the RAINFOR network said: "The increase in some pioneer trees, such as the extremely fast growing Cecropia, is consistent with the observed changes in forest dynamics, which may also ultimately be driven by increased carbon dioxide levels."

Co-author Dr Kyle Dexter, from the University of Edinburgh, said: "The impact of climate change on forest communities has important consequences for rain forest biodiversity. The species most vulnerable to droughts are doubly at risk, as they are typically the ones restricted to fewer locations in the heart of the Amazon, which make them more likely to be extinct if this process continues.

Read more at Science Daily

A toast to the proteins in dinosaur bones

Dinosaur blood vessel with adjacent bone matrix that still contains bone cells. These structures have a perfect morphological preservation over hundreds of millions of years, but are chemically transformed through oxidative crosslinking. The extract comes from a sauropod dinosaur.

Burnt toast and dinosaur bones have a common trait, according to a new, Yale-led study. They both contain chemicals that, under the right conditions, transform original proteins into something new. It's a process that may help researchers understand how soft-tissue cells inside dinosaur bones can survive for hundreds of millions of years.

A research team from Yale, the American Museum of Natural History, the University of Brussels, and the University of Bonn announced the discovery Nov. 9 in the journal Nature Communications.

Fossil soft tissue in dinosaur bones has been a controversial topic among researchers for quite some time. Hard tissues, such as bones, eggs, teeth, and enamel scales, are able to survive fossilization extremely well. Soft tissues, such as blood vessels, cells, and nerves -- which are stored inside the hard tissue -- are more delicate and thought to decay rapidly after death. These soft tissues are composed mainly of proteins, which are believed to completely degrade within about four million years.

Yet dinosaur bones are much older, roughly 100 million years old, and they occasionally preserve organic structures similar to cells and blood vessels. Various attempts to resolve this paradox have failed to provide a conclusive answer.

"We took on the challenge of understanding protein fossilization," said Yale paleontologist Jasmina Wiemann, the study's lead author. "We tested 35 samples of fossil bones, eggshells, and teeth to learn whether they preserve proteinaceous soft tissues, find out their chemical composition, and determine under what conditions they were able to survive for millions of years."

The researchers discovered that soft tissues are preserved in samples from oxidative environments such as sandstones and shallow, marine limestones. The soft tissues were transformed into Advanced Glycoxidation and Lipoxidation end products (AGEs and ALEs), which are resistant to decay and degradation. They're also structurally comparable to chemical compounds that stain the dark crust on toast.

AGEs and ALEs are characterized by a brownish color that stains fossil bones and teeth that contain them. The compounds are hydrophobic, which means they are resistant to the normal effects of water, and have properties that make it difficult for bacteria to consume them.

Wiemann and her colleagues made their discovery by decalcifying fossils and imaging the released soft tissue structures. They applied Raman microspectroscopy -- a non-destructive method for analyzing both the inorganic and organic contents of a sample -- to the extracted fossil soft tissues. During this process, laser energy directed at the tissue causes molecular vibrations that carry spectral fingerprints for the chemicals that are present.

Co-author Derek Briggs, Yale's G. Evelyn Hutchinson Professor of Geology and Geophysics and a curator at the Yale Peabody Museum of Natural History, said the study points to localities where soft tissue may be found in fossil bones, including sandstones deposited from rivers, dune sands, and shallow marine limestones.

"Our results show how chemical alteration explains the fossilization of these soft tissues and identifies the types of environment where this process occurs," Briggs said. "The payoff is a way of targeting settings in the field where this preservation is likely to occur, expanding an important source of evidence of the biology and ecology of ancient vertebrates."

Read more at Science Daily

Most complete study on Europe's greatest Hadrosaur site published

The Basturs Poble site is what is known in English as a bone bed, a geological stratum containing a great amount of fossils. The stratum dates back some 70 million years. It is the only one to have been found in Europe exclusively containing hadrosaur remains. The excavations conducted during the past ten years have yielded approximately one thousand fossils. The remains are disjointed and possibly belong to only one species: the Pararhabdodon isonensis. "We think the individuals died due to unfavourable environmental conditions, perhaps an extreme dry spell. After their death, the remains got washed away by water and then began to fossilise, but we know that the place where they died was not far away from the site," explains Víctor Fondevilla, researcher at the Institut Català de Paleontologia Miquel Crusafont (ICP) and the Universitat Autònoma de Barcelona (UAB) and first author of the paper.

The research recently published in PLOS ONE analysed the 270 fossil remains at the site which were prepared to be studied, including skulls, jaws, teeth, vertebrae and limb bones. Researchers however did not have enough with describing and measuring each specimen, they also analysed the interior of the fossils to extract information on the age of each individual. "We can cut open the fossils and analyse their inner structure. It gives us a lot of information on the vital cycle of each of the animals," says ICREA research lecturer at ICP Meike Köhler. Similar to the rings of trees, in sections of elongated bones we find lines of arrested growth (LAGs) which are indicators corresponding to the alternation between favourable and unfavourable periods. In this way we can calculate at what age they died.

Using this system, palaeontologists detected that at the site were a large number of young individuals and, to a lesser extent, sub-adults and adults. But no recently hatched dinosaur fossils were found. "We estimated that the youngest individuals died at two years of age and that the adults were 14 to 15," Fondevilla explains. The fact that researchers found so many young samples makes them think that the accumulation of bones at Basturs Poble represents a natural population of herbivores, where young individuals are more abundant. "It may also be that the abundance of young remains is due to these individuals being more vulnerable to crises and therefore dying in larger quantities than adults would," the main researcher of the study comments.

Also participating in the study were researchers from the Museum of Conca Dellà and the Friulian Museum of Natural History in Udine, Italy.

Hadrosaurs, A Well-Known Group in Catalonia

Hadrosaurs, also known as "duck-billed" dinosaurs, are a group of ornithischian herbivorous dinosaurs which lived in the Late Cretaceous period. This is probably the most well-known group of dinosaurs. Among the subfamilies there are the lambeosaurines, which can be found in Catalonia's sites. They characteristically had a robust medium to large-sized body (weighing one kilogramme when hatching and reaching up to 3000 kilogrammes as adults), with smaller front limbs and larger hind limbs. This last trait made it possible for them to walk on two or four feet indifferently.

The skull is long and duck-billed shaped, and the jaw holds rows of stacked teeth. Their most distinctive characteristic was their cranial crest, formed by several more or less developed cranial bones. What the crest was used for remains unclear, but scientists believe it could have acted as a resonating chamber with which to amplify sounds and facilitate recognising members of the same species. Other hypotheses point to the possibility of only males having crests which aimed to attract the females.

The Pararhabdodon isonensis species is only known to have existed in the Pallars Jussà region. [nbsp]The species was described in 1985 after the discovery of remains found at Sant Romà d'Abella and its specific name -- isonensis -- refers to the town of Isona located near the site. These dinosaurs measured from 6 to 7 metres in length and it is estimated that the adults weighed some three tonnes.

The Pyrenees, Home to the Last Dinosaurs in Europe

Catalonia is very rich in fossiliferous sediment. Of the most relevant are the pre-Pyrennean basins, which conserve remains of different life forms from the Late Cretaceous Period (between 70 and 66 million years ago). In geological terms, that is very shortly before the great extinction which marked the end of many life forms, including non-avian dinosaurs. Located at the Pyrennean sites, therefore, are the last dinosaurs to have lived in Europe, a few hundreds of years before they disappeared from the world entirely.

The Basturs Poble site was located by scientific communicator Marc Boada in August 2001. Upon discovering fossils on the surface, he contacted palaeontologists from the Museum of Conca Dellà. Few months later a palaeontology dig was conducted which confirmed the exceptional nature of this site. After a first research dig, twelve more campaigns have been conducted as part of research projects led by Àngel Galobart, Head of the Mesozoic Fauna Research Group at ICP, and Rodrigo Gaete from the Museum of Conca Dellà.

Read more at Science Daily

Aging a flock of stars in the Wild Duck Cluster

An image of the Wild Duck Cluster was captured by the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile. The blue stars at the center of the image are the stars of the cluster. Every star in the Wild Duck Cluster is roughly 250 million years old. Older, redder stars surround the cluster.

Do star clusters harbor many generations of stars or just one? Scientists have long searched for an answer and, thanks to the University of Arizona's MMT telescope, found one in the Wild Duck Cluster, where stars spin at different speeds, disguising their common age.

In a partnership between the UA and the Korean Astronomy and Space Science Institute, a team of Korean and Belgian astronomers used UA instruments to solve a puzzle about flocks of stars called open clusters.

Astronomers have long believed that many open clusters consist of a single generation of stars because once stars have formed, their radiation blows away nearby material needed to make new stars. But in the Wild Duck Cluster -- known by scientists as Messier 11, or M11 -- stars of the same brightness appear in different colors, suggesting they are of different ages. Unless scientists had missed important clues about stellar evolution, there had to be another explanation for the spread of colors in this accumulation of about 2,900 stars.

"Astronomers have been working on this question for decades," said Serena Kim, an associate astronomer at the UA's Steward Observatory. "Do clusters form in one generation or multiple generations? Our study answered this question for the Wild Duck Cluster."

Beomdu Lim of Kyung Hee University led an international team of astronomers who used the MMT telescope -- jointly operated by the UA and the Smithsonian Astrophysical Observatory -- to study the cluster. In a study published in Nature Astronomy, the team discovered that it is not the stars' ages that cause them to appear in a spread of color: it is their rotation.

Open clusters contain thousands of stars that astronomers hypothesize formed from the same giant clouds of gas. These stars come in all sizes, from short-lived, giant blue stars dozens of times more massive than our sun, to long-lived low-mass dwarves that will burn for 10 billion years or longer. The brightness and color of each star changes as it grows older, allowing scientists to determine its age.

"As a star is getting older and older, it brightens and becomes redder," Lim said.

Astronomers plot young stars' brightness and color in a diagonal line -- from bright, blue and massive at the top of the line, down to faint, red and less massive at the bottom -- called the main sequence.

The turning point -- the point at which a star ages and veers off the main sequence -- is used to determine the age of clusters based on the known life expectancy of each star. If the stars leave the main sequence at the same point, like cars on a freeway taking the same exit, then the stars of the cluster are all the same age.

In the Wild Duck Cluster, however, the stars veer off the diagonal at different points, like cars taking different exits along a freeway.

"This does not seem intuitive, since the stars in an open cluster like M11 are thought to belong to the same generation," Kim said.

Lim and his team set out to discover what stellar properties could potentially explain this pattern.

They turned the MMT telescope toward the cluster to examine the color spectrum of the stars using an Hectochelle. The instrument acts like a prism and spreads starlight into its components, which astronomers call a spectrum. The spectra are like barcodes, with each line identifying a different chemical in the star's makeup.

Hectochelle can capture detailed spectra of many stars at once, making it an ideal instrument to observe clusters like the Wild Duck, which consist of thousands of stars.

As a star rotates, one side of it is moving toward the Earth and the other is moving away. The half of the star rotating toward the Earth emits light with wavelengths that look squished, making the light look bluer than it would be if the star were not moving. The half of the star rotating away from the Earth causes the wavelengths to look stretched, making its light seem redder. This squishing and stretching causes spectral lines to spread across a range of wavelengths, rather than spiking at just one.

The stars in the Wild Duck Cluster, it turns out, are spread out in the color spectrum not because of different ages, but because of different rotational periods.

"The effects of rotation on stellar evolution were often neglected in the past," said Yaël Nazé, an astronomer at the University of Liège in Belgium and co-author of the paper.

The spectra also revealed that the stars are spinning at different rates. Lim and his team performed computer simulations to find out how fast each star is rotating.

"A rapidly rotating star can remain in the main sequence stage longer than a slowly rotating star," Lim said. "A wide range of velocities of stars results in differences of lifetimes among the stars."

Rotational speed is like a fountain of youth to a star: The faster it spins, the better it mixes hydrogen -- the star's fuel -- into its core. The more hydrogen the core receives, the longer the star lives, causing it to appear redder than younger siblings.

Stars in the cluster appear in different colors because the cloud they were born in set them into motion that would extend the lifetime for some of them.

Read more at Science Daily

DNA of world's oldest natural mummy unlocks secrets of Ice Age tribes in the Americas

These are skulls and other human remains from P.W. Lund's Collection from Lagoa Santa, Brazil kept in the Natural History Museum of Denmark.

A legal battle over a 10,600 year old ancient skeleton -- called the 'Spirit Cave Mummy' -- has ended after advanced DNA sequencing found it was related to a Native American tribe.

The revelation has been published in Science today (Thursday, November 8 at 14:00 US Eastern Time) as part of a wide ranging international study that genetically analysed the DNA of a series of famous and controversial ancient remains across North and South America including Spirit Cave, the Lovelock skeletons, the Lagoa Santa remains, an Inca mummy, and the oldest remains in Chilean Patagonia. The study also looked at the second oldest human remains from Trail Creek Cave in Alaska -- a 9,000 year old milk tooth from a young girl.

Scientists sequenced 15 ancient genomes spanning from Alaska to Patagonia and were able to track the movements of the first humans as they spread across the Americas at "astonishing" speed during the Ice Age, and also how they interacted with each other in the following millennia.

The team of academics not only discovered that the Spirit Cave remains -- the world's oldest natural mummy -- was a Native American but they were able to dismiss a longstanding theory that a group called Paleoamericans existed in North America before Native Americans.

The ground-breaking research also discovered clues of a puzzling Australasian genetic signal in the 10,400 year old Lagoa Santa remains from Brazil revealing a previously unknown group of early South Americans -- but the Australasian link left no genetic trace in North America. It was described by one of the scientists as 'extraordinary evidence of an extraordinary chapter in human history'.

Professor Eske Willeslev, who holds positions both at St John's College, University of Cambridge, and the University of Copenhagen, and led the study, said: "Spirit Cave and Lagoa Santa were very controversial because they were identified as so-called 'Paleoamericans' based on craniometry -- it was determined that the shape of their skulls was different to current day Native Americans. Our study proves that Spirit Cave and Lagoa Santa were actually genetically closer to contemporary Native Americans than to any other ancient or contemporary group sequenced to date."

The Lagoa Santa remains were retrieved by Danish explorer Peter W. Lund in the 19th century and his work led to this 'Paleoamerican hypothesis' based on cranial morphology that theorised the famous group of skeletons could not be Native Americans. But this new study disproves that theory and the findings were published by Professor Willeslev with representatives from the Brazilian National Museum in Rio on Tuesday, November 6 2018.

He added: "Looking at the bumps and shapes of a head does not help you understand the true genetic ancestry of a population -- we have proved that you can have people who look very different but are closely related."

The scientific and cultural significance of the Spirit Cave remains, which were found in 1940 in a small rocky alcove in the Great Basin Desert, was not properly understood for 50 years. The preserved remains of the man in his forties were initially believed to be between 1,500 and 2000 years old, but during the 1990s new textile and hair testing dated the skeleton at 10,600 years old.

The Fallon Paiute-Shoshone Tribe, a group of Native Americans based in Nevada near Spirit Cave, claimed cultural affiliation with the skeleton and requested immediate repatriation of the remains under the Native American Graves Protection and Repatriation Act.

The request was refused because the ancestry was disputed, the tribe sued the federal government and the lawsuit pitted tribal leaders against anthropologists, who argued the remains provided invaluable insights into North America's earliest inhabitants and should continue to be displayed in a museum.

The deadlock continued for 20 years until the tribe agreed that Professor Willeslev could carry out genome sequencing on DNA extracted from the Spirit Cave for the first time.

Professor Willeslev said: "I assured the tribe that my group would not do the DNA testing unless they gave permission and it was agreed that if Spirit Cave was genetically a Native American the mummy would be repatriated to the tribe."

The team painstakingly extracted DNA from the petrus bone from the inside of the skull proving that the skeleton was an ancestor of present day Native Americans. Spirit Cave was returned to the tribe in 2016 and there was a private reburial ceremony earlier this year that Professor Willeslev attended and details have just been released.

The geneticist explained: "What became very clear to me was that this was a deeply emotional and deeply cultural event. The tribe have real feelings for Spirit Cave, which as a European it can be hard to understand but for us it would very much be like burying our mother, father, sister or brother.

"We can all imagine what it would be like if our father or mother was put in an exhibition and they had that same feeling for Spirit Cave. It has been a privilege to work with them."

The tribe were kept informed throughout the two year project and two members visited the lab in Copenhagen to meet the scientists and they were present when all of the DNA sampling was taken.

A statement from the Fallon Paiute-Shoshone Tribe, said: "The Tribe has had a lot of experience with members of the scientific community, mostly negative. However, there are a handful of scientists that seemed to understand the Tribe's perspective and Eske Willerslev was one of them.

"He took the time to acquaint himself with the Tribe, kept us well-informed of the process, and was available to answer our questions. His new study confirms what we have always known from our oral tradition and other evidence -- that the man taken from his final resting place in Spirit Cave is our Native American ancestor."

The genome of the Spirit Cave skeleton has wider significance because it not only settled the legal and cultural dispute between the tribe and the Government, it also helped reveal how ancient humans moved and settled across the Americas. The scientists were able to track the movement of populations from Alaska to as far south as Patagonia. They often separated from each other and took their chances travelling in small pockets of isolated groups.

Dr David Meltzer, from the Department of Anthropology, Southern Methodist University, Dallas, said: "A striking thing about the analysis of Spirit Cave and Lagoa Santa is their close genetic similarity which implies their ancestral population travelled through the continent at astonishing speed. That's something we've suspected due to the archaeological findings, but it's fascinating to have it confirmed by the genetics. These findings imply that the first peoples were highly skilled at moving rapidly across an utterly unfamiliar and empty landscape. They had a whole continent to themselves and they were travelling great distances at breath-taking speed."

The study also revealed surprising traces of Australasian ancestry in ancient South American Native Americans but no Australasian genetic link was found in North American Native Americans.

Dr Victor Moreno-Mayar, from the Centre for GeoGenetics, University of Copenhagen and first author of the study, said: "We discovered the Australasian signal was absent in Native Americans prior to the Spirit Cave and Lagoa Santa population split which means groups carrying this genetic signal were either already present in South America when Native Americans reached the region, or Australasian groups arrived later. That this signal has not been previously documented in North America implies that an earlier group possessing it had disappeared or a later arriving group passed through North America without leaving any genetic trace."

Dr Peter de Barros Damgaard, from the Centre for GeoGenetics, University of Copenhagen, explained why scientists remain puzzled but optimistic about the Australasian ancestry signal in South America. He explained: "If we assume that the migratory route that brought this Australasian ancestry to South America went through North America, either the carriers of the genetic signal came in as a structured population and went straight to South America where they later mixed with new incoming groups, or they entered later. At the moment we cannot resolve which of these might be correct, leaving us facing extraordinary evidence of an extraordinary chapter in human history! But we will solve this puzzle."

The population history during the millennia that followed initial settlement was far more complex than previously thought. The peopling of the Americas had been simplified as a series of north to south population splits with little to no interaction between groups after their establishment.

The new genomic analysis presented in the study has shown that around 8,000 years ago, Native Americans were on the move again, but this time from Mesoamerica into both North and South America.

Researchers found traces of this movement in the genomes of all present-day indigenous populations in South America for which genomic data is available to date.

Read more at Science Daily

Unique study shows how bats maneuver

For the first time, researchers have succeeded in directly measuring the aerodynamics of flying animals as they manoeuvre in the air. Previously, the upstroke of the wings was considered relatively insignificant compared to the powerful downstroke but, in a new study, biologists at Lund University in Sweden have observed that it is on the upstroke of the wings that bats often turn.

"Until now, we have not known very much about what animals actually do when they fly, since we have focused on steady flight. Steady flight is in fact not very common for animals flying out in the wild. We have now conducted direct aerodynamic measurements on bats and we can see how flexible they are. They turn in several different ways depending on where they are in the wing-beat," explains Per Henningsson, a biologist at Lund University.

"It is really fascinating to see how complex and elegant the pattern of movement is, and how the bats choose the best solution just as they decide to start a manoeuvre," he continues.

For the bats, flight technique with fast manoeuvres at high speed is important to successfully capture insects in flight, as well as to avoid collision with various obstacles such as trees and buildings.

The results could be significant in the development of the next generation of drones.

"One of the main challenges for the industry is about control and stability and enabling drones to avoid obstacles easily. In that context, our results are very relevant," says Per Henningsson, who does not exclude the possibility of future drones being equipped with flapping wings.

The study was conducted on two long-eared bats that were trained to fly in a wind tunnel. As prey, the researchers used mealworms attached to a device that could be moved laterally. By moving the device to the right or to the left, the researchers made the bats turn to follow the direction of the prey. The researchers visualised the air flow and filmed the animals with high-speed cameras. This allowed them to link the aerodynamics to the movements.

The researchers behind the study are biologists from Lund University and the University of Southern Denmark.

Watch bat in flight: https://www.youtube.com/watch?v=j2zR37vo7Ss

From Science Daily

History of early settlement and survival in Andean highlands revealed by ancient genomes

This is the location of ancient samples near Lake Titicaca, elevation 3812 meters, in what is now Peru and Bolivia.

A multi-center study of the genetic remains of people who settled thousands of years ago in the Andes Mountains of South America reveals a complex picture of human adaptation from early settlement, to a split about 9,000 years ago between high and lowland populations, to the devastating exposure to European disease in the 16th-century colonial period.

Led by Anna Di Rienzo, PhD, and John Lindo, PhD, JD, from the University of Chicago; Mark Aldenderfer, PhD, from the University of California, Merced; and Ricardo Verdugo from the University of Chile, the researchers used newly available samples of DNA from seven whole genomes to study how ancient Andean people -- including groups that clustered around Lake Titicaca in Peru and Bolivia, 12,000 feet above sea level -- adapted to their environment over the centuries.

In the journal Science Advances, they compared their seven historical genomes to 64 modern-day genomes from a current highland Andean population, the agropastoral Aymara of Bolivia, and the lowland hunter-gatherer Huilliche-Pehuenche in coastal Chile.

The goals were (1) to date the initial migration to the Andean highlands, (2) to identify the genetic adaptations to the high-altitude environment that allowed that settlement, (3) to estimate the impact of the European contact starting in the 1530s that caused the near annihilation of many lowland communities of South America.

"We have very ancient samples from the high Andes," said Di Rienzo. "Those early settlers have the closest affinity to the people who now live in that area. This is a harsh, cold, resource-poor environment, with low oxygen levels, but people there adapted to that habitat and the agrarian lifestyle."

The study, "The Genetic prehistory of the Andean highlands 7,000 years BP through European contact," uncovered several unexpected features.

The researchers found that highland Andeans experienced much smaller than expected population declines following contact with European explorers who first came to South America in the 1530s. In the lowlands, demographic modeling and historical records infer that up to 90 percent of residents may have been wiped-out after the arrival of Europeans. But the people living in the upper Andes had only a 27-percent population reduction.

Even though the highlanders lived in altitudes above 8,000 feet, which meant reduced oxygen, frequent frigid temperatures and intense ultra-violet radiation, they did not develop the responses to hypoxia seen in natives of other high-altitude settings, such as Tibet.

The Andeans may have adapted to high altitude hypoxia "in a different way, via cardiovascular modifications," the researchers suggest. They found evidence of alterations in a gene called DST, which is associated with the formation of cardiac muscle. Andean highlanders tend to have enlarged right ventricles. This may have improved oxygen intake, enhancing blood flow to the lungs.

But the strongest adaptation signal the researchers found was in a gene called MGAM (maltase-glucoamylase) an intestinal enzyme. It plays an important role in the digestion of starchy foods such as potatoes -- a food native to the Andes. A recent study suggests that the potato may have been domesticated in the region at least 5,000 years ago. Positive selection on the MGAM gene, the authors note, "may represent an adaptive response to greater reliance upon starchy domesticates."

The early presence of this variant in Andean peoples suggests "a significant shift in diet from one that was likely more meat based to one more plant based," said UC Merced's Aldenderfer, an anthropologist. "The timing of the appearance of the variant is quite consistent with what we know of the paleo-ethno-botanical record in the highlands."

Although Andean settlers consumed a high-starch diet after they started to farm, their genomes did not develop additional copies of the starch related amylase gene, commonly seen in European farming populations.

A comparison of the ancient genomes with their living descendants also revealed selection for immune-related genes soon after the arrival of Europeans, suggesting that Andeans who survived may have had an advantage with regard to the newly introduced European pathogens.

"Contact with Europeans had a devastating impact on South American populations, such as the introduction of disease, war, and social disruption," explained Lindo. "By focusing on the period before that, we were able to distinguish environmental adaptations from adaptations that stemmed from historical events."

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Ancient DNA evidence reveals two unknown migrations from North to South America

This map depicts the findings of Posth et al., who conducted a large-scale analysis of ancient genomes from Central and South America yields insights into the peopling of the Americas, including four southward migration events and notable population continuity in much of South America after arrival.

An international research team has used genome-wide ancient DNA data to revise Central and South American history. Their analysis of DNA from 49 individuals spanning about 10,000 years in Belize, Brazil, the Central Andes, and southern South America has concluded that the majority of Central and South American ancestry arrived from at least three different streams of people entering from North America, all arising from one ancestral lineage of migrants who crossed the Bering Strait some time before 15,000 years ago.

The evidence, presented November 8 in the journal Cell, shows that within this one ancestral lineage, there were two previously undocumented streams of gene flow from North to South America, one of which was later displaced in a major population replacement that began at least 9,000 years ago.

"Our work multiplied the number of ancient genomes available from these areas by about 20, giving us a much more comprehensive picture of indigenous history in the Americas," says co-senior author David Reich, a geneticist at Harvard Medical School and the Howard Hughes Medical Institute. "This broader dataset reveals a common origin of North, Central, and South Americans as well as two previously unknown genetic exchanges between North and South America."

"Nearly all Central and South Americans arose from a star-like radiation of the first lineage into at least three branches," says co-lead author Cosimo Posth, an archaeogeneticist from the Max Planck Institute for the Science of Human History. "That means that nearly all the ancestry of Central and South Americans came from the same source population, albeit one that had already diversified prior to its spread into South America. With DNA evidence largely based on present-day people, those multiple gene flow events are undetectable, highlighting the power of ancient DNA data."

The genome analysis also yielded new insights on the Clovis culture-related people, who were mainly distributed across North America from about 13,000 years ago. Archaeological evidence from Clovis sites shows that the spread of Clovis artefacts did not expand throughout South America. But when the researchers used genome-sequencing technology to generate and compare genomes from a previously published ~13,000-year-old Clovis-related genome in Montana to the earliest genomes analyzed from South and Central America dating to between ~9,000 and ~11,000 years ago, they noticed significant shared ancestry. That suggested that the people who spread the Clovis culture also left a major impact much father south through people producing non-Clovis-specific stone tools.

"We weren't expecting to find a relation to people associated with the Clovis culture in South America," says co-first author Nathan Nakatsuka, a PhD student in Reich's lab at Harvard. "But it seems the expansion of the Clovis-associated lineage extended to parts of Central and South America."

The paper concludes that this Clovis-related lineage contributed substantially to a group of 9,000-10,000-year-old individuals from Lagoa Santa in Brazil, inconsistent with the hypothesis that the people from this site derived from a separate migration from Asia. The authors also detected the Clovis-related genetic affinity in an even older, almost ~11,000-year-old individual from Chile and a slightly younger, more than ~9,000-year-old individual from Belize.

Beginning around ~9,000 years ago with ancient samples in Peru, however, the authors detected an almost complete disappearance of the Clovis culture-associated ancestry in Central and South America, documenting a remarkable population replacement. The large-scale population replacement is a process that was not widely expected by archaeologists," says Reich. "This is an exciting example of how ancient DNA studies can reveal events in the past that were not confirmed and thus can stimulate new work in archaeology."

The researchers also showed that after this major population turnover, there was striking continuity compared to other parts of the world like Eurasia and Africa. "There is remarkable continuity between earlier and later skeletons with South Americans today," says Posth. "For example, modern-day Quechua and Aymara from the Central Andes can trace their ancestry back to the ancient people of the Cuncaicha site from 9,000 years ago onwards. This is a longer-standing continuity than you see in other continents."

The researchers recognize that there is much more work to do to fully flesh out the history of the Americas.

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Orangutans spontaneously bend straight wires into hooks to fish for food

Male orangutan using a stick tool.

The bending of a hook into wire to fish for the handle of a basket is surprisingly challenging for young children under eight years of age. Now cognitive biologists and comparative psychologists from the University of Vienna, the University of St Andrews and the University of Veterinary Medicine Vienna working with Isabelle Laumer and Alice Auersperg studied hook tool making for the first time in a non-human primate species -- the orangutan. To the researchers' surprise the apes spontaneously manufactured hook tools out of straight wire within the very first trial and in a second task unbent curved wire to make a straight tool.

Human children are already proficient tool-users and tool-makers from an early age on. Nevertheless, when confronted with a task, which required them to innovate a hooked tool out of a straight piece of wire in order to retrieve a basket from the bottom of a vertical tube, the job proved more challenging for children than one might think: Three to five-year-old children rarely succeed and even at the age of seven less than half of them were able to solve the task. Only at the age of eight the majority of children was able to innovate a hook-tool. Interestingly children of all tested age classes succeeded when given demonstrations on how to bend a hook and use it. Thus, although young children apparently understand what kind of tool is required and are skilled enough to make a functional tool, there seems to be a cognitive obstacle in innovating one.

Cognitive biologists and comparative psychologists have now tested for the first time a primate species in the hook-bending task. "We confronted the orangutans with a vertical tube containing a reward basket with a handle and a straight piece of wire. In a second task with a horizontal tube containing a reward at its centre and a piece of wire that was bent at 90°," explains Isabelle Laumer who conducted the study at the Zoo Leipzig in Germany. "Retrieving the reward from the vertical tube thus required the orangutans to bent a hook into the wire to fish the basket out of the tube. The horizontal tube in turn required the apes to unbent the bent piece of wire in order to make it long enough to push the food out of the tube."

Several orangutans mastered the hook bending task and the unbending task. Two orangutans even solved both tasks within the first minutes of the very first trial. "The orangutans mostly bent the hooks directly with their teeth and mouth while keeping the rest of the tool straight. Thereafter they immediately inserted it in correct orientation, hooked the handle and pulled the basket up," she further explains.

Orangutans share 97% of their DNA with us and are among the most intelligent primates. They have human-like long-term memory, routinely use a variety of sophisticated tools in the wild and construct elaborate sleeping nests each night from foliage and branches. Today orangutans can only be found in the rainforests of Sumatra and Borneo. Like all four great ape species, orangutans are listed as critically endangered (IUCN, Red List). "Habitat loss due to extensive palm-oil production, illegal wildlife trade and poaching are the major threats. Palm oil is the most widely used vegetable oil in the world. As long as there is a demand for palm oil and consumers keep buying products that contain palm oil, the palm industry thrives. According to a 2007 survey by the United Nations Environment Program (UNEP) orangutans will be extinct in the wild within two decades if current deforestation trends continue," says Isabelle Laumer.

"The hook-bending task has become a benchmark paradim to test tool innovation abilities in comparative psychology," says Alice Auersperg from the University of Veterinary Medicine in Vienna. "Considering the speed of their hook innovation, it seems that they actively invented a solution to this problem rather than applying routined behaviours."

"Finding this capacity in one of our closest relatives is astonishing. In human evolution hook tools appear relatively late. Fish hooks and harpoon-like, curved objects date back only approximately 16,000- 60,000 years. Although New Caledonian crows use hooks with regularity, there are a few observations of wild apes, such as chimpanzees and orangutans, that use previously detached branches to catch and retrieve out-of-reach branches for locomotion in the canopy. This branch-hauling tools might represents one of the earliest and simplest raking tools used and made by great apes and our ancestors," says Josep Call of the University of St Andrews.

Read more at Science Daily

Goffin's cockatoos can create and manipulate novel tools

A Goffin cockatoo tears off a strip of cardboard.

Goffin's cockatoos can tear cardboard into long strips as tools to reach food -- but fail to adjust strip width to fit through narrow openings, according to a study published November 7, 2018 in the open-access journal PLOS ONE by A.M.I. Auersperg from the Medical University of Vienna, Austria, and colleagues.

The Goffin's cockatoo (Cacatua goffiniana) is a type of parrot. Captive Goffins are capable of inventing and manipulating tools, even though they aren't known to use tools habitually. The authors of the present study investigated two questions: do Goffins adjust tool properties to save effort, and if so, how accurately can they adjust tool dimensions for the task? The authors supplied six adult cockatoos with large cardboard sheets to tear into strips as tools for the testing apparatus: a food platform with a food reward set at varying distances (4-16cm) behind a small opening which also varied in width (1-2cm).

They found that the Goffins were capable of adjusting the length of their cardboard strip tools to account for variations in food distance, making shorter tools when the reward was closer than when it was set farther away. In every case, if a first-attempt tool was too short, the second-attempt tool would be significantly longer. On average, all six birds made significantly longer tools than were required to reach the reward in all test conditions, with the birds tending to make increasingly long tools as the study progressed -- perhaps as a risk-avoidance strategy.

However, only one bird was able to make a sufficiently-narrow tool to successfully reach the food reward when the opening was at its narrowest. The authors hypothesize that the shearing technique the birds use to tear the cardboard limits the narrowness of the resulting strips. The authors suggest that future studies provide less restrictive materials to assess whether Goffins are cognitively capable of adjusting tool width in this situation.

Alice Auersperg adds: "The way they inserted and discarded manufactured pieces of specific lengths differently depending on condition suggests that the cockatoos could indeed adjust their tool making behavior in the predicted direction but with some limits in accuracy."

From Science Daily

Moths survive bat predation through acoustic camouflage fur

Moths are a mainstay food source for bats, which use echolocation to hunt their prey. Scientists are studying how moths have evolved passive defenses over millions of years to resist their primary predators. While some moths have evolved ears that detect the ultrasonic calls of bats, many types of moths remain deaf. In those moths, researchers have found that the insects developed types of "stealth coating" that serve as acoustic camouflage to evade hungry bats. Neil will describe his work during the Acoustical Society of America's 176th Meeting, Nov. 5-9. This image shows a Madagascar bullseye (Antherina suraka), one of the moth species used in Thomas Neil's research.

Moths are a mainstay food source for bats, which use echolocation (biological sonar) to hunt their prey. Scientists such as Thomas Neil, from the University of Bristol in the U.K., are studying how moths have evolved passive defenses over millions of years to resist their primary predators.

While some moths have evolved ears that detect the ultrasonic calls of bats, many types of moths remain deaf. In those moths, Neil has found that the insects developed types of "stealth coating" that serve as acoustic camouflage to evade hungry bats.

Neil will describe his work during the Acoustical Society of America's 176th Meeting, held in conjunction with the Canadian Acoustical Association's 2018 Acoustics Week, Nov. 5-9 at the Victoria Conference Centre in Victoria, Canada.

In his presentation, Neil will focus on how fur on a moth's thorax and wing joints provide acoustic stealth by reducing the echoes of these body parts from bat calls.

"Thoracic fur provides substantial acoustic stealth at all ecologically relevant ultrasonic frequencies," said Neil, a researcher at Bristol University. "The thorax fur of moths acts as a lightweight porous sound absorber, facilitating acoustic camouflage and offering a significant survival advantage against bats." Removing the fur from the moth's thorax increased its detection risk by as much as 38 percent.

Neil used acoustic tomography to quantify echo strength in the spatial and frequency domains of two deaf moth species that are subject to bat predation and two butterfly species that are not.

In comparing the effects of removing thorax fur from insects that serve as food for bats to those that don't, Neil's research team found that thoracic fur determines acoustic camouflage of moths but not butterflies.

"We found that the fur on moths was both thicker and denser than that of the butterflies, and these parameters seem to be linked with the absorptive performance of their respective furs," Neil said. "The thorax fur of the moths was able to absorb up to 85 percent of the impinging sound energy. The maximum absorption we found in butterflies was just 20 percent."

Neil's research could contribute to the development of biomimetic materials for ultrathin sound absorbers and other noise-control devices.

Read more at Science Daily

Scientists theorize new origin story for Earth's water

This view of Earth's horizon was taken by an Expedition 7 crew member onboard the International Space Station, using a wide-angle lens while the Station was over the Pacific Ocean.

Earth's water may have originated from both asteroidal material and gas left over from the formation of the Sun, according to new research. The new finding could give scientists important insights about the development of other planets and their potential to support life.

In a new study in the Journal of Geophysical Research: Planets, a journal of the American Geophysical Union, researchers propose a new theory to address the long-standing mystery of where Earth's water came from and how it got here.

The new study challenges widely-accepted ideas about hydrogen in Earth's water by suggesting the element partially came from clouds of dust and gas remaining after the Sun's formation, called the solar nebula.

To identify sources of water on Earth, scientists have searched for sources of hydrogen rather than oxygen, because the latter component of water is much more abundant in the solar system.

Many scientists have historically supported a theory that all of Earth's water came from asteroids because of similarities between ocean water and water found on asteroids. The ratio of deuterium, a heavier hydrogen isotope, to normal hydrogen serves as a unique chemical signature of water sources. In the case of Earth's oceans, the deuterium-to-hydrogen ratio is close to what is found in asteroids.

But the ocean may not be telling the entire story of Earth's hydrogen, according to the study's authors.

"It's a bit of a blind spot in the community," said Steven Desch, a professor of astrophysics in the School of Earth and Space Exploration at Arizona State University in Tempe, Arizona and co-author of the new study, led by Peter Buseck, Regents' Professor in the School of Earth and Space Exploration and School of Molecular Sciences at Arizona State University. "When people measure the [deuterium-to-hydrogen] ratio in ocean water and they see that it is pretty close to what we see in asteroids, it was always easy to believe it all came from asteroids."

More recent research suggests hydrogen in Earth's oceans does not represent hydrogen throughout the entire planet, the study's authors said. Samples of hydrogen from deep inside the Earth, close to the boundary between the core and mantle, have notably less deuterium, indicating this hydrogen may not have come from asteroids. Noble gases helium and neon, with isotopic signatures inherited from the solar nebula, have also been found in the Earth's mantle.

In the new study, researchers developed a new theoretical model of Earth's formation to explain these differences between hydrogen in Earth's oceans and at the core-mantle boundary as well as the presence of noble gases deep inside the planet.

Modeling Earth's beginning

According to their new model, several billion years ago, large waterlogged asteroids began developing into planets while the solar nebula still swirled around the Sun. These asteroids, known as planetary embryos, collided and grew rapidly. Eventually, a collision introduced enough energy to melt the surface of the largest embryo into an ocean of magma. This largest embryo would eventually become Earth.

Gases from the solar nebula, including hydrogen and noble gases, were drawn in by the large, magma-covered embryo to form an early atmosphere. Nebular hydrogen, which contains less deuterium and is lighter than asteroidal hydrogen, dissolved into the molten iron of the magma ocean.

Through a process called isotopic fractionation, hydrogen was pulled towards the young Earth's center. Hydrogen, which is attracted to iron, was delivered to the core by the metal, while much of the heavier isotope, deuterium, remained in the magma which eventually cooled and became the mantle, according to the study's authors. Impacts from smaller embryos and other objects then continued to add water and overall mass until Earth reached its final size.

This new model would leave Earth with noble gases deep inside its mantle and a lower deuterium-to-hydrogen ratio in its core than in its mantle and oceans.

The authors used the model to estimate how much hydrogen came from each source. They concluded most was asteroidal in origin, but some of Earth's water did come from the solar nebula.

"For every 100 molecules of Earth's water, there are one or two coming from solar nebula," said Jun Wu, assistant research professor in the School of Molecular Sciences and School of Earth and Space Exploration at Arizona State University and lead author of the study.

An insightful model

The study also offers scientists new perspectives about the development of other planets and their potential to support life, the authors said. Earth-like planets in other solar systems may not all have access to asteroids loaded with water. The new study suggests these exoplanets could have obtained water through their system's own solar nebula.

"This model suggests that the inevitable formation of water would likely occur on any sufficiently large rocky exoplanets in extrasolar systems," Wu said. "I think this is very exciting."

Anat Shahar, a geochemist at the Carnegie Institution for Science, who was not involved with the study, noted the hydrogen fractionation factor, which describes how the deuterium-to-hydrogen ratio changes when the element dissolves in iron, is currently unknown and difficult to measure. For the new study, this property of hydrogen had to be estimated.

The new model, which fits in well with current research, could be tested once experiments reveal the hydrogen fractionation factor, Shahar said.

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Astronomers find pairs of black holes at the centers of merging galaxies

These images reveal the final stage of a union between pairs of galactic nuclei in the messy cores of colliding galaxies. The image at top left, taken by Hubble's Wide Field Camera 3, shows the merging galaxy NGC 6240. A close-up of the two brilliant cores of this galactic union is shown at top right. This view, taken in infrared light, pierces the dense cloud of dust and gas encasing the two colliding galaxies and uncovers the active cores. The hefty black holes in these cores are growing quickly as they feast on gas kicked up by the galaxy merger. The black holes' speedy growth occurs during the last 10 million to 20 million years of the merger. Images of four other colliding galaxies, along with close-up views of their coalescing nuclei in the bright cores, are shown beneath the snapshots of NGC 6240. The images of the bright cores were taken in near-infrared light by the W. M. Keck Observatory in Hawaii, using adaptive optics to sharpen the view. The reference images (left) of the merging galaxies were taken by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS). The two nuclei in the Hubble and Keck Observatory photos are only about 3,000 light-years apart -- a near-embrace in cosmic terms. If there are pairs of black holes, they will likely merge within the next 10 million years to form a more massive black hole. These observations are part of the largest-ever survey of the cores of nearby galaxies using high-resolution images in near-infrared light taken by the Hubble and Keck observatories. The survey galaxies' average distance is 330 million light-years from Earth.

For the first time, a team of astronomers has observed several pairs of galaxies in the final stages of merging together into single, larger galaxies. Peering through thick walls of gas and dust surrounding the merging galaxies' messy cores, the research team captured pairs of supermassive black holes -- each of which once occupied the center of one of the two original smaller galaxies -- drawing closer together before they coalescence into one giant black hole.

Led by University of Maryland alumnus Michael Koss (M.S. '07, Ph.D. '11, astronomy), a research scientist at Eureka Scientific, Inc., with contributions from UMD astronomers, the team surveyed hundreds of nearby galaxies using imagery from the W.M. Keck Observatory in Hawaii and NASA's Hubble Space Telescope. The Hubble observations represent more than 20 years' worth of images from the telescope's lengthy archive. The team described their findings in a research paper published on November 8, 2018, in the journal Nature.

"Seeing the pairs of merging galaxy nuclei associated with these huge black holes so close together was pretty amazing," Koss said. "In our study, we see two galaxy nuclei right when the images were taken. You can't argue with it; it's a very 'clean' result, which doesn't rely on interpretation."

The high-resolution images also provide a close-up preview of a phenomenon that astronomers suspect was more common in the early universe, when galaxy mergers were more frequent. When the black holes finally do collide, they will unleash powerful energy in the form of gravitational waves -- ripples in space-time recently detected for the first time by the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors.

The images also presage what will likely happen in a few billion years, when our Milky Way galaxy merges with the neighboring Andromeda galaxy. Both galaxies host supermassive black holes at their center, which will eventually smash together and merge into one larger black hole.

The team was inspired by a Hubble image of two interacting galaxies collectively called NGC 6240, which later served as a prototype for the study. The team first searched for visually obscured, active black holes by sifting through 10 years' worth of X-ray data from the Burst Alert Telescope (BAT) aboard NASA's Neil Gehrels Swift Observatory.

"The advantage to using Swift's BAT is that it observes high-energy, 'hard' X-rays," said study co-author Richard Mushotzky, a professor of astronomy at UMD and a fellow of the Joint Space-Science Institute (JSI). "These X-rays penetrate through the thick clouds of dust and gas that surround active galaxies, allowing the BAT to see things that are literally invisible in other wavelengths."

The researchers then combed through the Hubble archive, zeroing in on the merging galaxies they spotted in the X-ray data. They then used the Keck telescope's super-sharp, near-infrared vision to observe a larger sample of the X-ray-producing black holes not found in the Hubble archive.

The team targeted galaxies located an average of 330 million light-years from Earth -- relatively close by in cosmic terms. Many of the galaxies are similar in size to the Milky Way and Andromeda galaxies. In total, the team analyzed 96 galaxies observed with the Keck telescope and 385 galaxies from the Hubble archive.

Their results suggest that more than 17 percent of these galaxies host a pair of black holes at their center, which are locked in the late stages of spiraling ever closer together before merging into a single, ultra-massive black hole. The researchers were surprised to find such a high fraction of late-stage mergers, because most simulations suggest that black hole pairs spend very little time in this phase.

To check their results, the researchers compared the survey galaxies with a control group of 176 other galaxies from the Hubble archive that lack actively growing black holes. In this group, only about one percent of the surveyed galaxies were suspected to host pairs of black holes in the later stages of merging together.

This last step helped the researchers confirm that the luminous galactic cores found in their census of dusty interacting galaxies are indeed a signature of rapidly-growing black hole pairs headed for a collision. According to the researchers, this finding is consistent with theoretical predictions, but until now, had not been verified by direct observations.

"People had conducted studies to look for these close interacting black holes before, but what really enabled this particular study were the X-rays that can break through the cocoon of dust," explained Koss. "We also looked a bit farther in the universe so that we could survey a larger volume of space, giving us a greater chance of finding more luminous, rapidly-growing black holes."

It is not easy to find galactic nuclei so close together. Most prior observations of merging galaxies have caught the coalescing black holes at earlier stages, when they were about 10 times farther away. The late stage of the merger process is so elusive because the interacting galaxies are encased in dense dust and gas, requiring very high-resolution observations that can see through the clouds and pinpoint the two merging nuclei.

"Computer simulations of galaxy smashups show us that black holes grow fastest during the final stages of mergers, near the time when the black holes interact, and that's what we have found in our survey," said Laura Blecha, an assistant professor of physics at the University of Florida and a co-author of the study. Blecha was a JSI Prize Postdoctoral Fellow in the UMD Department of Astronomy prior to joining UF's faculty in 2017. "The fact that black holes grow faster and faster as mergers progress tells us galaxy encounters are really important for our understanding of how these objects got to be so monstrously big."

Future infrared telescopes such as NASA's highly anticipated James Webb Space Telescope (JWST), slated for launch in 2021, will provide an even better view of mergers in dusty, heavily obscured galaxies. For nearby black hole pairs, JWST should also be capable of measuring the masses, growth rates and other physical parameters for each black hole.

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Bioreactor device helps frogs regenerate their legs

This image shows Xenopus laevis swimming in a tank pre-amputation.

A team of scientists designed a device that can induce partial hindlimb regeneration in adult aquatic African clawed frogs (Xenopus laevis) by "kick-starting" tissue repair at the amputation site. Their findings, appearing November 6 in the journal Cell Reports, introduce a new model for testing "electroceuticals," or cell-stimulating therapies.

"At best, adult frogs normally grow back only a featureless, thin, cartilaginous spike," says senior author Michael Levin, developmental biologist at the Allen Discovery Center at Tufts University. "Our procedure induced a regenerative response they normally never have, which resulted in bigger, more structured appendages. The bioreactor device triggered very complex downstream outcomes that bioengineers cannot yet micromanage directly."

The scientists 3D printed the bioreactor out of silicon and filled it with hydrogel -- a sticky glob of polymers. They laced the hydrogel with hydrating silk proteins that promote healing and regeneration, then added progesterone. Progesterone is best known for its role in preparing the uterus for pregnancy, but the hormone has also been shown to promote nerve, blood vessel, and bone tissue repair.

The researchers split the frogs into three groups: experimental, control, and sham. For the experimental and sham group, they sutured the device on the frogs immediately after limb amputation. In the experimental group, the bioreactor released progesterone onto the amputation site. In all cases, they removed the devices after 24 hours.

When they looked at the experimental group frogs at different time points over 9.5 months, they noticed that the bioreactor seemed to trigger a degree of limb regeneration not observed in the other groups. Instead of a typical spike-like structure, the bioreactor treatment resulted in a paddle-like formation closer to a fully formed limb than unaided regeneration could create.

"The bioreactor device created a supportive environment for the wound where the tissue could grow as it did during embryogenesis," says Levin. "A very brief application of bioreactor and its payload triggered months of tissue growth and patterning."

Levin and his team took a closer look at the regenerated structures using molecular and histology analyses. They saw that, unlike in the control and sham groups, the regenerating limbs of the bioreactor-treated frogs were thicker with more developed bones, innervation, and vascularization. Analyzing video footage of the frogs in their tanks, they also noticed that the frogs could swim more like unamputated frogs.

RNA sequencing and transcriptome analysis revealed that the bioreactor had altered the gene expression occurring in cells at the amputation site. Genes involved in oxidative stress, serotonergic signalling, and white blood cell activity were upregulated, while some other signaling-related genes were downregulated.

The researchers also observed that scarring and immune responses were downregulated in the bioreactor-treated frogs, suggesting that the added progesterone dampened the body's natural reaction to injury in a way that benefited the regeneration process.

"In both reproduction and its newly discovered role in brain functioning, progesterone's actions are local or tissue-specific," says first author Celia Herrera-Rincon, neuroscientist in Levin's lab at Tufts University. "What we are demonstrating with this approach is that maybe reproduction, brain processing, and regeneration are closer than we think. Maybe they share pathways and elements of a common -- and so far, not completely understood -- bioelectrical code."

Levin's lab will continue to target bioelectric processes for inducing spinal cord regeneration and tumor reprogramming. They also hope to replicate their bioreactor experiment in mammals. Previous research suggests that mice can partially regenerate amputated fingertips in the right conditions, but their life on land hinders this process.

"Almost all good regenerators are aquatic," says Levin. "You can imagine why this matters: a mouse that loses a finger or hand, and then grinds the delicate regenerative cells into the flooring material as it walks around, is unlikely to experience significant limb regeneration."

Read more at Science Daily

Family tree of 400 million people shows genetics has limited influence on longevity

How long you live has less to do with your genes than you might think.

Although long life tends to run in families, genetics has far less influence on life span than previously thought, according to a new analysis of an aggregated set of family trees of more than 400 million people. The results suggest that the heritability of life span is well below past estimates, which failed to account for our tendency to select partners with similar traits to our own. The research, from Calico Life Sciences and Ancestry, was published in GENETICS, a journal of the Genetics Society of America.

"We can potentially learn many things about the biology of aging from human genetics, but if the heritability of life span is low, it tempers our expectations about what types of things we can learn and how easy it will be," says lead author Graham Ruby. "It helps contextualize the questions that scientists studying aging can effectively ask."

Ruby's employer, Calico Life Sciences, is a research and development company whose mission is to understand the biology of aging. They teamed up with scientists from the online genealogy resource Ancestry, led by Chief Scientific Officer Catherine Ball, to use publicly available pedigree data from Ancestry.com to estimate the heritability of human life span.

Heritability is a measure of how much of the variation in a trait -- in this case life span -- can be explained by genetic differences, as opposed to non-genetic differences like lifestyle, sociocultural factors, and accidents. Previous estimates of human life span heritability have ranged from around 15 to 30 percent.

"Partnering with Ancestry allowed this new study to gain deeper insights by using a much larger data set than any previous studies of longevity," said Ball.

Starting from 54 million subscriber-generated public family trees representing six billion ancestors, Ancestry removed redundant entries and those from people who were still living, stitching the remaining pedigrees together. Before sharing the data with the Calico research team, Ancestry stripped away all identifiable information from the pedigrees, leaving only the year of birth, year of death, place of birth (to the resolution of state within the US and country outside the US), and familial connections that make up the tree structure itself.

They ended up with a set of pedigrees that included over 400 million people -- largely Americans of European descent -- each connected to another by either a parent-child or a spouse-spouse relationship. The team was then able to estimate heritability from the tree by examining the similarity of life span between relatives.

Using an approach that combines mathematical and statistical modeling, the researchers focused on relatives who were born across the 19th and early 20th centuries, finding heritability estimates for siblings and first cousins to be roughly the same as previously reported. But, as was also observed in some of the previous studies, they noted that the life span of spouses tended to be correlated -- they were more similar, in fact, than in siblings of opposite gender.

This correlation between spouses could be due to the many non-genetic factors that accompany living in the same household -- their shared environment. But the story really started to take shape when the authors compared different types of in-laws, some with quite remote relationships.

The first hint that something more than either genetics or shared environment might be at work was the finding that siblings-in-law and first-cousins-in-law had correlated life spans -- despite not being blood relatives and not generally sharing households.

The size of their dataset allowed the team to zoom in on longevity correlations for other more remote relationship types, including aunts and uncles-in-law, first cousins-once-removed-in-law, and different configurations of co-siblings-in-law. The finding that a person's sibling's spouse's sibling or their spouse's sibling's spouse had a similar life span to their own made it clear that something else was at play.

If they don't share genetic backgrounds and they don't share households, what best accounts for the similarity in life span between individuals with these relationship types? Going back to their impressive dataset, the researchers were able to perform analyses that detected assortative mating.

"What assortative mating means here is that the factors that are important for life span tend to be very similar between mates," says Ruby. In other words, people tend to select partners with traits like their own -- in this case, how long they live.

Of course, you can't easily guess the longevity of a potential mate. "Generally, people get married before either one of them has died," jokes Ruby. Because you can't tell someone's life span in advance, assortative mating in humans must be based on other characteristics.

The basis of this mate choice could be genetic or sociocultural -- or both. For a non-genetic example, if income influences life span, and wealthy people tend to marry other wealthy people, that would lead to correlated longevity. The same would occur for traits more controlled by genetics: if, for example, tall people prefer tall spouses, and height is correlated in some way with how long you live, this would also inflate estimates of life span heritability.

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Cosmic fountain offers clues to how galaxies evolve

Artist impression of Abell 2597 showing the central supermassive black hole expelling cold, molecular gas -- like the pump of a giant intergalactic fountain.

Galaxy evolution can be chaotic and messy, but it seems that streams of cold gas spraying out from the region around supermassive black holes may act to calm the storm.

This is according to an international team of scientists who have provided the first clear and compelling evidence of this process in action.

Using the Atacama Large Millimetre/submillimetre Array (ALMA) of telescopes, the team, which includes researchers from Cardiff University, has observed a supermassive black hole acting like a 'monumental fountain' in the middle of a galaxy over a billion light-years from Earth.

At the centre of the galaxy, named Abell 2597, the black hole is drawing in vast stores of cold molecular gas and then spraying them back out again in an ongoing cycle.

The giant elliptical galaxy Abell 2597 lies at the heart of one of the universe's most massive structures and has a sprawling cluster of other galaxies surrounding it.

According to the researchers, this entire system operates via a self-regulating feedback loop. The incoming material provides power for the fountain as it "drains" toward the central black hole, like water entering the pump of a fountain. This gas then causes the black hole to ignite with activity, launching high-velocity jets of super-heated material that shoot out of the galaxy.

As it travels, this material pushes out clumps and streamers of gas into the galaxy's expansive halo, where it eventually rains back in on the black hole, triggering the entire process anew.

By studying the location and motion of molecules of carbon monoxide (CO) with ALMA, which shine brightly in millimetre-wavelength light, the researchers were able to measure the motion of the gas as it falls in toward the black hole.

It is from these plumes of gas that new stars are formed in galaxies, and the researchers believe that the process they have observed could be common across the Universe and, more importantly, could be crucial to the development of massive galaxies like this one.

Dr Timothy Davis, from the School of Physics and Astronomy at Cardiff University, said: "Galaxy evolution can be pretty chaotic, and big galaxies like this tend to live hard and die young. For the first time we have been able to observe the full cycle of a supermassive black hole fountain, that acts to regulate this process, prolonging the life of galaxies."

"The supermassive black hole at the centre of this giant galaxy acts like a mechanical 'pump' in a water fountain," said Grant Tremblay, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and lead author on the paper.

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Elusive star has origins close to Big Bang

The star, named 2MASS J18082002–5104378 B, is part of a two-star system orbiting around a common point.

Astronomers have found what could be one of the universe's oldest stars, a body almost entirely made of materials spewed from the Big Bang.

The discovery of this approximately 13.5 billion-year-old tiny star means more stars with very low mass and very low metal content are likely out there -- perhaps even some of the universe's very first stars.

The star is unusual because unlike other stars with very low metal content, it is part of the Milky Way's "thin disk" -- the part of the galaxy in which our own sun resides.

And because this star is so old, researchers say it's possible that our galactic neighborhood is at least 3 billion years older than previously thought. The findings are published in The Astrophysical Journal.

"This star is maybe one in 10 million," said lead author Kevin Schlaufman, a Johns Hopkins University assistant professor of physics and astronomy. "It tells us something very important about the first generations of stars."

The universe's first stars after the Big Bang would have consisted entirely of elements like hydrogen, helium, and small amounts of lithium. Those stars then produced elements heavier than helium in their cores and seeded the universe with them when they exploded as supernovae.

The next generation of stars formed from clouds of material laced with those metals, incorporating them into their makeup. The metal content, or metallicity, of stars in the universe increased as the cycle of star birth and death continued.

The newly discovered star's extremely low metallicity indicates that, in a cosmic family tree, it could be as little as one generation removed from the Big Bang. Indeed, it is the new record holder for the star with the smallest complement of heavy elements -- it has about the same heavy element content as the planet Mercury. In contrast, our sun is thousands of generations down that line and has a heavy element content equal to 14 Jupiters.

Astronomers have found around 30 ancient "ultra metal-poor" stars with the approximate mass of the sun. The star Schlaufman and his team found, however, is only 14 percent the mass of the sun.

The star is part of a two-star system orbiting around a common point. The team found the tiny, almost invisibly faint "secondary" star after another group of astronomers discovered the much brighter "primary" star. That team measured the primary's composition by studying a high-resolution optical spectrum of its light. The presence or absence of dark lines in a star's spectrum can identify the elements it contains, such as carbon, oxygen, hydrogen, iron, and more. In this case, the star had extremely low metallicity. Those astronomers also identified unusual behavior in the star system that implied the presence of a neutron star or black hole. Schlaufman and his team found that to be incorrect, but in doing so, they discovered the visible star's much smaller companion.

The existence of the smaller companion star turned out to be the big discovery. Schlaufman's team was able to infer its mass by studying the primary star's slight "wobble" as the little star's gravity tugged at it.

As recently as the late 1990s, researchers believed that only massive stars could have formed in the earliest stages of the universe -- and that they could never be observed because they burn through their fuel and die so quickly.

But as astronomical simulations became more sophisticated, they began to hint that in certain situations, a star from this time period with particularly low mass could still exist, even more than 13 billion years since the Big Bang. Unlike huge stars, low-mass ones can live for exceedingly long times. Red dwarf stars, for instance, with a fraction of the mass of the sun, are thought to live to trillions of years.

The discovery of this new ultra metal-poor star, named 2MASS J18082002-5104378 B, opens up the possibility of observing even older stars.

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