If an effective rapid diagnostic test were available – one that was non-invasive and effective, many of these missing cases of leprosy and close contacts of patients could be diagosed, without the need for blanket prescriptions of rifampicin to potentially healthy individuals. The good news is that these diagnostic tests are currently under development – though they may not be available for some time.
To study the disease and its progression and develop diagnostic tests, scientists often need to inject M. leprae into armadillos, a technique that was first attempted in 1971. “The fact that we cannot culture [grow] this bacteria so easily in laboratory settings is another factor hindering the progress of developing these tests,” says Sunkara.
New horizons
Since 2000, Novartis Foundation has partnered with the WHO, supplying drugs free of cost globally for multi-drug therapy. In February 2022, they partnered with Fiocruz for a study that uses artificial intelligence (AI) to accelerate leprosy diagnosis. “I call it applying state-of-the-art technology to an ancient disease,” says Sunkara.
There are at least 20-30 other skin diseases that present as white patches on the skin, says Sunkara. Using the AI algorithm to analyse the way light reflects differently off the surface of each skin disease, it’s possible to identify leprosy cases, distinguishing them from other similar conditions with far more accuracy. Their study, published in Lancet Regional Health, pegged the accuracy at 90% – but with 1,229 skin images, the data set remains small at the moment. If it succeeds on a larger scale, it might one day be a useful tool to help speed up diagnosis and treatment.
Continuing stigma
While modern advances in the treatment and diagnosis of leprosy have been life-changing for many patients, there’s one problem that has never quite gone away: relentless discrimination.
“Leprosy remains a deep-rooted human rights issue,” says Alice Cruz, the UN Special Rapporteur on the elimination of discrimination against persons affected by leprosy, a role she’s held since November 2017. There are more than a hundred laws that discriminate against people with leprosy worldwide, creating a strong stigma that can act as a barrier for getting treatment, she says.
In some countries, leprosy is grounds for divorce. In India, this was the case until laws were amended in 2019. Many people affected by the disease still struggle to get jobs, and the disease can hinder their access to healthcare and education.
“Countries should do everything in their power to have discriminatory laws abolished and to put in place policy that can guarantee economic and social rights to people affected by leprosy,” says Cruz. “Going forward, we should ask ourselves the question: are our healthcare systems working to afford full accessibility to persons affected by leprosy? This is because leprosy is much more than a disease, it became a label that dehumanises people who are affected by it.”
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At nightfall, after the day’s final scenes of flamingo sunbeams fade to black, he peers up at the sky to watch space rocks swimming along our solar system’s gravitational tides. Sometimes, he sees shards casually cruising next to Earth, greeting telescopes with a gentle “hey,” never to be observed again. But occasionally, he catches one on a crash course with our delicate blue orb.
Last year, Santana-Ros, a planetary scientist at the University of Alicante in Spain, sprang into action when astronomers realized an asteroid named 2022 WJ1 was headed straight for the border of Canada and the US. With barely four hours on the clock, he mustered his team to help pinpoint how menacing this asteroid would be. What towns would it threaten? Would it be like the dinosaur-killing Chicxulub or merely make a “plop” sound before sinking into a sturdy body of water?
“Luckily,” he concluded, “the object was small and just produced a spectacular fireball.”
But what if such a time-sensitive asteroid warning had been sent out in November 2020, when Santana-Ros’ telescopes were shut down because of bushfires ravaging the region and covering lenses with inky layers of ash? Or in February of 2021, when bushfire debris made its way into some telescopes, forcing astronomers to dismount instruments and pull blobs of soot from them after the wind settled?
“Climate change is already affecting astronomy and my work,” Santana-Ros said.
Time and again, studies have shown that climate change is leading to an increase in wildfire occurrence and severity as the years go by. With our present greenhouse gas emission trajectory, some models even predict that the risk of very large wildfires in the US will increase sixfold by the middle of the century.
During his telescope shutdowns, Santana-Ros said, he’d received the interruption news while comfortably at home. “There was no big drama.”
But those blazes prevented his team from using telescopes for a few weeks.
“The bottom line here is that this time we were lucky and we missed just some regular observations,” he said. “Next time, we might be facing a real threat.”
An astronomical problem
Over the last few decades, climate change has altered our relationship with Earth.
Global industries still burn coal to make cheap power, diffuse dangerous fossil fuel waste into the atmosphere, force our planet to heat up, and ultimately fuel devastation like the wildfires responsible for the interruption of Santana-Ros’ research. Meanwhile, scientists are trying to learn how to shelter endangered animals left without homes because deforestation has ruined wildlife habitats, as well as how to deal with cyclones tearing apart coastal villages.
It’s almost like we aren’t part of our planet anymore, no longer blended into its environment like the oak trees and butterflies with which we share cosmic material. It’s as if we’re fighting to regain our rightful place as Earthlings.
But amid such chaos, astronomers are starting to think about another heartbreaking angle to the crisis. Not only has our relationship with Earth grown fraught, but climate change could stain our relationship with the rest of the universe, too.
With global warming ramping up, ground-based telescopes will find it harder to alert us about asteroids, show us glistening galaxies and deliver views of mysterious exoplanets populating the rest of eternity – wonders that unite us underneath our layers of disagreement, as evidenced by the ubiquitous love we witnessed for NASA’s James Webb Space Telescope two Christmases ago.
Cyclones, floods, fires and droughts are becoming the norm in astronomy hubs like Hawaii and New Mexico. Sites like the Les Makes Observatory were hit by severe storms at the same time Santana-Ros had to contend with wildfires near his tools in Australia.
And it’s not just full-on disasters that we have to worry about. It’s also the smaller things: changes in temperature, humidity, steady weather – elements telescopes usually rely on to operate in tip-top shape.
A recent paper, published last October in the journal Astronomy & Astrophysics, focuses on those crucial details while outlining an ominous future for astronomy. Its authors explore the specifics of what climate change could do to eight major optical telescopes scattered across the globe. Not just today, but by 2050.
“Our results show that climate change will negatively impact the quality of astronomical observations,” they say, “and is likely to increase time lost due to bad site conditions.”
Time lost, as in nights of stargazing compromised.
“My first reaction to the paper was ‘yikes’ – yet another depressing outcome of climate change,” said Clara Sousa-Silva, a quantum astrophysicist at Bard College. “I had not previously considered how it would affect future observations, but of course it makes perfect sense. Obviously, in the long list of tragedies that will come from a warming Earth, this is very far down the list of concerns, but it is nonetheless concerning.”
“Anecdotally,” she continued, though carefully noting the probability of confirmation bias, “observational colleagues have complained that there seem to be more and more nights lost to weather in recent years.”
Starlight’s barrier
Along with her advisors, Caroline Haslebacher, a doctoral student at the University of Bern in Switzerland and lead author of the recent study, realized no one had really looked into how climate change will affect astronomical observations, though Santana-Ros’ experience is evidence that damage is already being done.
They quickly moved to fill the gap.
The team modeled what would happen to those eight telescope subjects as the globe heats up, eventually suggesting we’ll see an increase in what’s known as specific humidity and precipitable water vapor in the coming years.
Essentially, this means the amount of water in the air will get higher because of climate change – a problematic situation because airborne water tends to absorb the same light telescopes are trying their hardest to catch.
“A lot of the most exciting astronomical observations are done at the very edge of instrumental capabilities,” Sousa-Silva said. “Any additional noise directly restricts the discoveries we can make.”
For instance, the study authors expect that on the extinct volcano of Mauna Kea in Hawaii, where many observatories lie, there’ll be an increase of 0.3 mm of water by the year 2050. Granted, such a miniature impact seemed quite soft when compared with other sites. “But still not zero,” John O’Meara, chief scientist at Mauna Kea’s Keck Observatory, said.
With this paper in mind, he’s particularly worried about increases in water vapor affecting not visible light but rather infrared observations at the Hawaiian location. Such haze is very likely to pose problems for this category of light, which emanates from the distant universe.
Because wavelengths stretch out as they move farther and farther away from our planet, they get redder and redder and redder over time until they turn into elusive infrared patterns – invisible to human eyes but analyzable with advanced machines. This is precisely the form of light signals that scientists love, the kind that could reveal to us what the universe was like when it flicked on for the first time.
It’d be a shame for such a rich level of cosmic history to slowly fade away from our vantage point on Earth.
“Climate change effects were not historically included in site selection studies, and now we have a new variable to consider,” O’Meara said.
Because of this, Haslebacher believes that going forward, we should analyze trends when building telescopes.
“It is urgent for telescopes under construction,” she said, “since these canstill adapt their design for changing climate conditions, and telescopes in planning so that a minimally impacted site can be selected.”
But even that effort may not be enough to offset the barriers this crisis will create. More water vapor simply reduces light transmission in some spectral bands. Or as Sousa-Silva puts it, “we will literally have less to look at.”
The lonely space machines
Since the Industrial Revolution, it’s almost like humanity has existed in a dissonant thought loop regarding climate change – one that has, expectedly, turned into a political debate.
Last year, COP27 marked the 27th year that world leaders have met to discuss how to save Earth – and another year world scientists confirmed we’re pretty much failing.
“I have to emphasize at this point that we investigated the shared socioeconomic pathway scenario with the highest greenhouse gas emissions out of five possible pathways,” Haslebacher said of her paper. “Unfortunately, we are following this scenario today.”
In other words, the worst-case scenario is the scenario we’re currently living through.
Yet some policymakers and energy giants justify this kind of human rebellion against the natural world – and even encourage it – because fossil fuels give us inexpensive power. And without affordable energy, they worry, we’d need to dip into other financial budgets as penance for keeping our iPhone batteries a healthy green hue.
But to sustain fossil fuel-driven power, we pay in other ways.
“We know what we as a nation and a world need to do to avoid the worst effects, and yet we are largely unwilling to act at the scale that the situation demands,” O’Meara said. “I worry that it will take the first truly major catastrophe or conflict to wake us up, and by then, it may well be too late to avoid the next one.”
Further, the same pollution that’s heating up the globe is also bound to do things like thicken the atmosphere.
“An optically thick atmosphere is one in which radiation travels less,” said Luigi Vidale, a professor of Climate System Science and Climate Hazards at the University of Reading and co-author of the study. “Although [our] models considered the highest future emission scenario, we may still have underestimated the impact of airborne pollution on local visibility.”
O’Meara explained it simply: “More clouds equals less visibility for faint objects equals less science.”
To name a few more consequences: Global warming could degrade the overall atmospheric qualities of a telescope’s site, forming the right conditions for turbulence during observations. It could prevent scientists from cooling their machines down to the right checkpoints before embarking on a project – and, truth be told, concerns are deep enough to impact not just astronomy, but all science.
“It will change our whole world,” Santana-Ros said. “It is quite likely that climate change can be the source of future financial crises, which in turn will have a negative effect on research funding.”
Funding for science projects is already a huge conundrum – most of the time, only those who win grants, awards, scholarships and other such prizes are able to pursue their work for years on end.
So to add on to that, if we wait to act on climate change, and then something utterly drastic happens, we’d need to redirect resources from astronomy, medicine, chemistry, biology, botany and so on, into climate science.
“There is still time for science and industry to lead us to a better climate future,” O’Meara said. “All we need is the resolve and the investment.” It’s becoming clearer that without immediate action, the promise of ground-based telescopes might one day become a thing of the past – dying out alongside all the other beautiful things humans are tasked with protecting from the catastrophe they created.
At that point, the only link we’d have left to the stars would be our space-borne machines: the Webb Space Telescope, the Hubble – chunks of metal floating above a ravaged Earth, witnesses to humanity’s exit from the natural world.
“Plans for colonization of other planets are still sci-fi, and will still be for several decades,” Santana-Ros said. “Our only option to survive is to mitigate climate change.”
An international team of scientists has found that changes in Earth’s orbit that favored hotter conditions may have helped trigger a rapid global warming event 56 million years ago known as the Paleocene-Eocene Thermal Maximum (PETM).
An international team of scientists has suggested that changes in Earth’s orbit that resulted in hotter conditions may have played a role in triggering a rapid global warming event that occurred 56 million years ago. This event, known as the Paleocene-Eocene Thermal Maximum (PETM), is considered to be an analog to modern-day climate change.
“The Paleocene-Eocene Thermal Maximum is the closest thing we have in the geologic record to anything like what we’re experiencing now and may experience in the future with climate change,” said Lee Kump, professor of geosciences at Penn State University. “There has been a lot of interest in better resolving that history, and our work addresses important questions about what triggered the event and the rate of carbon emissions.”
The team of scientists studied core samples from a well-preserved record of the PETM near the Maryland coast using astrochronology, a method of dating sedimentary layers based on orbital patterns that occur over long periods of time, known as Milankovitch cycles.
Victoria Fortiz (right), then a graduate student at Penn State, and Jean Self-Trail, a research geologist at the U.S. Geological Survey, work on a core sample from the Howards Tract site in Maryland. Credit: Penn State
They found the shape of Earth’s orbit, or eccentricity, and the wobble in its rotation, or precession, favored hotter conditions at the onset of the PETM and that these orbital configurations together may have played a role in triggering the event.
“An orbital trigger may have led to the carbon release that caused several degrees of global warming during the PETM as opposed to what’s a more popular interpretation at the moment that massive volcanism released the carbon and triggered the event,” said Kump, the John Leone Dean in the College of Earth and Mineral Sciences.
The findings, published in the journal
“Those rates are close to an order of magnitude slower than the rate of carbon emissions today, so that is cause for some concern,” Kump said. “We are now emitting carbon at a rate that’s 5 to 10 times higher than our estimates of emissions during this geological event that left an indelible imprint on the planet 56 million years ago.”
The scientists conducted a time series analysis of calcium content and magnetic susceptibility found in the cores, which are proxies for changes in orbital cycles, and used that information to estimate the pacing of the PETM.
Earth’s orbit varies in predictable, calculable ways due to gravitational interactions with the sun and other planets in the solar system. These changes impact how much sunlight reaches Earth and its geographic distribution and therefore influence the climate.
“The reason there’s an expression in the geologic record of these orbital changes is because they affect climate,” Kump said. “And that affects how productive marine and terrestrial organisms are, how much rainfall there is, how much erosion there is on the continents, and therefore how much sediment is carried into the ocean environment.”
Erosion from the paleo Potomac and Susquehanna rivers, which at the onset of the PETM may have rivaled the discharge of the Amazon River, carried sediments to the ocean where they were deposited on the continental shelf. This formation, called the Marlboro Clay, is now inland and offers one of the best-preserved examples of the PETM.
“We can develop histories by coring down through the layers of sediment and extracting specific cycles that are creating this story, just like you could extract each note from a song,” Kump said. “Of course, some of the records are distorted and there are gaps — but we can use the same types of statistical methods that are used in apps that can determine what song you are trying to sing. You can sing a song and if you forget half the words and skip a chorus, it will still be able to determine the song, and we can use that same approach to reconstruct these records.”
Reference: “Astrochronology of the Paleocene-Eocene Thermal Maximum on the Atlantic Coastal Plain” by Mingsong Li, Timothy J. Bralower, Lee R. Kump, Jean M. Self-Trail, James C. Zachos, William D. Rush and Marci M. Robinson, 24 September 2022, Nature Communications. DOI: 10.1038/s41467-022-33390-x
The study was funded by the National Key R&D Program of China and the Heising-Simons Foundation.
A well-known riddle compares an egg to treasure, asking: A box without hinges, key or a lid, yet inside golden treasure is hid. What am I?
And for archaeologists in Israel, eight prehistoric ostrich eggs – thought to be between 4,000 and 7,500 years old – proved as valuable as treasure when they were discovered near an ancient fire pit in the Negev, a desert region in the south of the country.
They were discovered during an archaeological excavation in the agricultural fields of Be’er Milka, the Israel Antiquities Authority (IAA) announced on Thursday.
The eggs’ proximity to the fire pit suggests that they were collected intentionally by the prehistoric desert nomads who used the campsite, according to a press release from IAA, although further lab analysis will provide more information about their uses and age.
“We found a campsite, which extends over about 200 sq. m (2,153 square feet) that was used by the desert nomads since prehistoric times,” Lauren Davis, the IAA excavation director, said in the release.
“At the site we found burnt stones, flint and stone tools as well as pottery sherds, but the truly special find is this collection of ostrich eggs. Although the nomads did not build permanent structures at this site, the finds allow us to feel their presence in the desert.”
Davis added that the campsites were covered over by the dunes, keeping the eggs exceptionally well-preserved.
The IAA, which told CNN on Thursday the site had been excavated in the last week, said that ostriches were common in the region until they became extinct in the wild during the 19th century.
Their eggs were ornately decorated and were prized items among the elite circles of Mediterranean civilizations during the Bronze and Iron Ages.
As well as being used as decorative items, ostrich eggs were also used in funerals, as water canteens and as a source of food.
“We find ostrich eggs in archaeological sites in funerary contexts, and as luxury items and water-canteens. Naturally, they were used as a source of food: one ostrich egg has the nutritional value of about 25 normal chicken eggs,” said Amir Gorzalczany, senior research archaeologist from IAA, in the release.
“It is interesting, that whilst ostrich eggs are not uncommon in excavations, the bones of the large bird are not found. This may indicate that in the ancient world, people avoided tackling the ostrich and were content with collecting their eggs.”
If you had the grooming habits of a Neanderthal, perhaps it’s a good thing your nose wasn’t as sensitive to urine and sweat as a modern human’s.
And if you lived the hunting and gathering lifestyle of a Denisovan on the Asian steppes, your strong nose for energy-rich honey was almost certainly an advantage.
Though we can’t really know what these two extinct human species perceived or preferred to eat, a new study from Duke University scientists has figured out a bit more about what they might have been able to smell.
Using a technique they developed that allows researchers to test smell sensitivity on odor receptors grown in a lab dish, researchers Claire de March of CNRS Paris Saclay University and Hiroaki Matsunami of Duke University were able to compare the scents-abilities of three kinds of humans. Their work appeared Dec. 28 in the open access journal iScience.
Drawing from published databases of genomes, including ancient DNA collections amassed by 2022 Nobel Prize winner Svante Pääbo, the researchers were able to characterize the receptors of each of the three human species by looking at the relevant genes.
“It is very difficult to predict a behavior just from the genomic sequence,” said de March, who performed this work as a postdoctoral research associate at Duke. “We had the odorant receptor genomes from Neanderthal and Denisovan individuals and we could compare them with today’s humans and determine if they resulted in a different protein.”
So then they tested the responses of 30 lab-grown olfactory receptors from each hominin against a battery of smells to measure how sensitive each kind of receptor was to a particular fragrance.
The laboratory tests showed the modern and ancient human receptors were essentially detecting the same odors, but their sensitivities differed.
The Denisovans, who lived 30,000 to 50,000 years ago, were shown to be less sensitive to the odors that present-day humans perceive as floral, but four times better at sensing sulfur and three times better at balsamic. And they were very attuned to honey.
“We don’t know what Denisovans ate, but there some reasons why this receptor has to be sensitive,” said Matsunami, who is a professor of molecular genetics and microbiology in the Duke School of Medicine. Contemporary hunter-gatherers such as the Hadza of Tanzania are famous for their love of honey, an essential high-calorie fuel.
Neanderthals, who were still around up to 40,000 years ago and who apparently swapped a few genes with modern humans, were three times less responsive to green, floral and spicy scents, using pretty much the same receptors we have today. “They may exhibit different sensitivity, but the selectivity remains the same,” Matsunami said.
“The Neanderthal odorant receptors are mostly the same as contemporary humans, and the few that were different were no more responsive,” de March added.
Odor receptors have been linked to ecological and dietary needs in many species and presumably evolve as a species changes ranges and diets.
“Each species must evolve olfactory receptors to maximize their fitness for finding food,” Matsunami said. “In humans, it’s more complicated because we eat a lot of things. We’re not really specialized.”
The lab has also used their cell-based scent tester for seeing genetic variation among modern humans. “Some people can smell certain chemicals, but others can’t,” Matsunami said. “That can be explained by functional changes.”
More information:
Claire A. de March et al, Genetic and functional odorant receptor variation in the Homo lineage, iScience (2022). DOI: 10.1016/j.isci.2022.105908
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The Webb Space Telescope’s latest target is one previously imaged by Hubble: the distant barred spiral galaxy EGS23205. Targets like this one will boost our understanding of the early universe and how ancient stars and galaxies took form.
The two images above show EGS23205 as seen by Hubble and Webb. Hubble’s image of the galaxy (taken in near-infrared) is much noisier, and the structure of the galaxy is harder to discern. But Webb’s image (at mid-infrared wavelengths) is much crisper, revealing a clear bar of stars stretching out from the galactic center.
Stellar bars are huge galactic cross-sections composed of countless stars. The bars play an important role in galactic evolution; they push gas toward the galactic center, helping fuel star formation and feed the supermassive black holes that lie within galactic nuclei. Our own Milky Way is a barred spiral galaxy.
Analysis of the image was submitted to the preprint server arXiv last year. Webb has imaged many ancient galaxies in its mere six months of scientific operations.
Some of Webb’s targets are among the earliest galaxies yet seen, and they appear to Webb as they were just several hundred million years after the Big Bang (the universe is now close to 14 billion years old).
Webb telescope reveals Milky Way–like galaxies in young universe
EGS23205 is seen as it was about 11 billion years ago. The image reveals that even early galaxies had well-defined bars (spiral galaxies were previously thought to be much later arrivals in the universe).
G/O Media may get a commission
“The bars hardly visible in Hubble data just popped out in the JWST image, showing the tremendous power of JWST to see the underlying structure in galaxies,” said Shardha Jogee, an astronomer at UT Austin and co-author of the research, in a press release.
Webb has previously imaged other objects once captured by Hubble. In October, the new $10 billion observatory beheld the Pillars of Creation, huge plumes of gas and dust in the Eagle Nebula. In the same month, the Webb team produced an image of merging galaxies 270 million light-years from Earth, imaged by Hubble back in 2008.
The two space telescopes observe at different wavelengths for the most part—Hubble primarily at visible wavelengths and Webb primarily in the infrared and near-infrared. Webb’s vivid handiwork is built on the mechanical shoulders of Hubble. Side-by-side image comparisons show the differences in these impressive observatories, and what’s possible with the newest technology.
We can confidently say that birds are dinosaur descendants, though paleontologists are still puzzled as to how this incredible evolutionary event occurred.
Now a complete fossilized skeleton of a bird that lived in what is today China around 120 million years ago might help clarify key steps in the transformation process, presenting with a more archaic, dinosaur-like head atop a body that has more in common with modern birds.
The transition from dinosaur to bird includes some of the most dramatic changes in shape, function, and environment, which ultimately led to the body plan that is typical of today’s birds.
Some of those shifting features can still be seen in the way modern birds develop. But the order in which these changes occurred, and the nature of the evolutionary pressures that gave rise to strictly avian characteristics, is still open for debate.
Photograph of the 120-million-year-old bird Cratonavis zhui. (Wang Min)
The fascinating, newly found fossil, named Cratonavis zhui, may provide important insights into the evolution of modern birds.
Researchers discovered the body print of Cratonavis, the bird with a dinosaur head, during excavations conducted in northern China.
Body prints of feathered dinosaurs and early birds, including Confuciusornis sanctus, have been discovered in this region, in sedimentary rocks formed about 120 million years ago, during the Cretaceous period.
Led by paleontologist Zhou Zhonghe from the Chinese Academy of Sciences (CAS), the scientists began their investigation of the fossil skull with high-resolution computed tomography (CT) scanning.
Using the digital versions of the mineralized bones, the team reconstructed the shape and function of the skull as it was during the bird’s life.
Artist’s impression of the 120-million-year-old bird Cratonavis zhui. (Zhao Chang)
The result shows that the shape of the Cratonavis skull is almost the same as that of dinosaurs like Tyrannosaurus rex, and not like a bird’s.
“The primitive cranial features speak to the fact that most Cretaceous birds such as Cratonavis could not move their upper bill independently with respect to the braincase and lower jaw, a functional innovation widely distributed among living birds that contributes to their enormous ecological diversity,” says CAS paleontologist Zhiheng Li.
The unusual combination of a dinosaur’s akinetic skull with a bird’s skeleton adds to previous studies on the importance of evolutionary mosaicism in the early diversification of birds.
Among the avian branches of the dinosaur’s family tree, Cratonavis is between the long-tailed Archaeopteryx, which was more like a reptile, and the Ornithothoraces, which had already developed many of the traits of modern birds.
Also of interest is the fact the Cratonavis fossil has a surprisingly long scapula and first metatarsal (foot bone) – features which are rarely seen in the fossils of other dino-ancestors to birds, and altogether absent in modern birds.
Evolutionary trends show reduced length in the first metatarsal as birds developed.
The study authors propose that during the change from dinosaurs to birds, the first metatarsal went through a process of natural selection that made it shorter. Once it reached its optimal size, which was less than a quarter of the length of the second metatarsal, it lost its earlier functions.
The unique feature of an enlarged metatarsal in Cratonavis is more comparable to the Late Cretaceous Balaur, a member of a group of feathered carnivores known as dromaeosaurids.
The elongated scapula has been observed 2.0.CO;2″>previously in Cretaceous birds such as Yixianornis and Apsaravis.
The fact that Cratonavis had a very long scapula probably made up for the fact that it didn’t have a breastbone adapted to provide the meaty pectoral muscles a larger surface to attach to. This extinct species may have contributed to a biological experiment in flying behavior.
One of the lead authors, paleontologist Min Wang, explains “the elongate scapula could augment the mechanical advantage of muscle for humerus retraction/rotation, which compensates for the overall underdeveloped flight apparatus in this early bird, and these differences represent morphological experimentation in volant behavior early in bird diversification”.
The authors mention the abnomal morphologies of the scapula and metatarsals preserved in Cratonavis highlight the breadth of skeletal plasticity in early birds.
Cratonavis zhui‘s unique mix of anatomy is less a stepping stone between two majestic categories of animals, but a sign of how all living things represent increments of change, and the evolution of birds of all feather occurred simultaneously along a wide variety of divergent paths.
The research has been published in Nature Ecology & Evolution.
Enlarge / Auroral display over snow-capped mountains in Hangzhou, China.
Liu Míng Sun/EyeEm/Getty Images
There’s rarely time to write about every cool science-y story that comes our way. So this year, we’re once again running a special Twelve Days of Christmas series of posts, highlighting one science story that fell through the cracks in 2022, each day from December 25 through January 5. Today: New analysis of an ancient Chinese text revealed the earliest candidate aurora yet found, predating the next oldest by three centuries.
A pair of researchers has identified the earliest description of a candidate aurora yet found in an ancient Chinese text, according to an April paper published in the journal Advances in Space Research. The authors peg the likely date of the event to either 977 or 957 BCE. The next earliest description of a candidate aurora is found on Assyrian cuneiform tablets dated between 679-655 BCE, three centuries later.
As we’ve reported previously, the spectacular kaleidoscopic effects of the so-called northern lights (or southern lights if they are in the Southern Hemisphere) are the result of charged particles from the Sun being dumped into the Earth’s magnetosphere, where they collide with oxygen and nitrogen molecules—an interaction that excites those molecules and makes them glow. Auroras typically present as shimmering ribbons in the sky, with green, purple, blue, and yellow hues.
There are different kinds of auroral displays, such as “diffuse” auroras (a faint glow near the horizon), rarer “picket fence” and “dune” displays, and “discrete aurora arcs”—the most intense variety, which appear in the sky as shimmering, undulating curtains of light. Discrete aurora arcs can be so bright, it’s possible to read a newspaper by their light. That was the case in August and September 1859, when there was a major geomagnetic storm—aka, the Carrington Event, the largest ever recorded—that produced dazzling auroras visible throughout the US, Europe, Japan, and Australia.
The Bamboo Annals is a chronicle of ancient China, written on bamboo strips, that begins with the age of the Yellow Emperor and runs through the so-called Warring States period (5th century–221 BCE), when rival states were engaged in intense competition. It ended when the state of Qin unified the states. The original text of the Bamboo Annals was buried with King Xiang of Wei, who died in 296 BCE, and wasn’t discovered until 281 CE, thus surviving Emperor Qin Shi Huang’s burning of the books in 212 BCE (not to mention burying hundreds of Confucian scholars alive).
Bamboo Annals.”>
Enlarge / Variant fragments of the Bamboo Annals.
M.A. van der Sluijs & H. Hayakawa, 2022
The original text consisted of 13 scrolls that were lost during the Song dynasty (960–1279 CE). There are two versions of the Bamboo Annals still in existence. One is known as the “current text,” consisting of two scrolls printed in the late 16th century. Many scholars believe this text is a forgery, given the many discrepancies between its text and portions of the original quoted in older books, although some scholars have argued that some parts might be faithful to the original text. The other version is known as the “ancient text,” and was pieced together by studying the aforementioned quoted portions found in older books, especially two dating back to the early 8th century CE.
Independent researcher Marinus Anthony van der Sluijs and Hisashi Hayakawa ofNagoya University relied on the ancient text for their new analysis. This text describes the appearance of a “five-colored light” visible in the northern part of the night sky towards the end of the reign of King Zhao of the Zhou dynasty. Auroras tend to only be visible in polar regions because the particles follow the Earth’s magnetic field lines, which fan out from the vicinity of the poles. But powerful geomagnetic storms can cause the auroral ovals to expand into lower latitudes, often accompanied by multicolored lights. Per the authors, during the 10th century BCE, Earth’s north magnetic pole was about 15 degrees closer to central China than today, so the people there may well have witnessed such displays.
While this is technically an unconfirmed candidate aurora, “The explicit mention of nighttime observation rules out daytime manifestations of atmospheric optics, which sometimes mimic candidate events,” the authors wrote. Furthermore, “The occurrence of a multicolored phenomenon in the northern sky during the nighttime is consistent with visual auroral displays in mid-latitude regions.” According to van der Sluijs and Hayakawa, the 16th century current text’s translation of the passage in question described the event as a “comet,” rather than a “five-colored light,” which is why the candidate aurora has not been identified until now.
DOI: Advances in Space Research, 2022. 10.1016/j.asr.2022.01.010 (About DOIs).
There may have been no oxygen in the atmosphere of ancient Mars after all, a new study has found — but don’t despair, there still could have been living creatures crawling on the planet’s surface.
When NASA’s Curiosity roverfound manganese oxide in Martian rocks in 2016, many planetary scientists rejoiced, believing that the mineral’s presence was a significant hint of past concentrations of oxygen in the planet’s atmosphere. The odds of past existence of life on Mars suddenly seemed higher, too, as oxygen is one of the key enablers of life on Earth.
A new study based on laboratory experiments, however, has now concluded that not only were high concentrations of oxygen not necessary for the formation of the minerals, but that the expected composition of ancient Mars’ atmosphere would have prevented oxygen-reliant reactions in the first place. Instead, the scientists said, copious amounts of manganese oxide could have formed on Mars simply in the presence of halogen elements, such as chlorine and bromine, which are found on the Red Planet in greater quantities than on Earth.
Related: Curiosity rover: 15 awe-inspiring photos of Mars (gallery)
“Oxidation does not necessitate the involvement of oxygen by definition,” Kaushik Mitra, now a planetary geochemist at Stony Brook University in New York who led this study as part of his graduate research work at Washington University in St. Louis, said in a statement (opens in new tab).
Oxidation is a chemical reaction in which a molecule or atom loses electrons. The reaction doesn’t necessarily involve oxygen, but in many cases leads to the formation of oxides, such as manganese oxide found on Mars.
“Earlier, we proposed viable oxidants on Mars, other than oxygen or via UV [ultraviolet] photooxidation, that help explain why the Red Planet is red,” he said. “In the case of manganese, we just did not have a viable alternative to oxygen that could explain manganese oxides until now.”
Kaushik and his collaborators were inspired by observations of reactions occuring during chlorination of drinking water, which involves adding molecules containing chlorine into water to kill microorganisms through oxidation. The researchers decided to test whether oxidation could be occurring in the halogen-rich environment on Mars. In a laboratory, they created water samples with a composition similar to what might have been found on ancient Mars. When they submerged fragments of manganese minerals in the water, the scientists discovered that the manganese quickly dissolved, forming manganese oxide thousands to millions of times faster than in the presence of oxygen, the researchers said in the statement.
The key to this stunning rate of oxidation, the scientists determined, was that the water contained chlorate and bromate, forms of the halogens chlorine and bromine that are common on Mars. Bromate was particularly efficient in turning manganese into manganese oxides, enabling the reaction to proceed at a speedy pace. That held true even when the water samples had high concentrations of carbon dioxide, which prohibited the formation of manganese oxides in the presence of only oxygen.
This finding is key to disproving the theory about past abundance of oxygen in the atmosphere of Mars that emerged after Curiosity’s discovery. Scientists also believe that the atmosphere of ancient Mars was rich in carbon dioxide, so because carbon dioxide blocked the reactions with oxygen, the idea that the formation of manganese oxides required high concentrations of atmospheric oxygen appeared to no longer hold water.
“The link between manganese oxides and oxygen suffers from an array of fundamental geochemical problems,” Jeffrey Catalano, a geochemist at Washington University, St, Louis, and corresponding author of the study, said in the statement. “Halogens occur on Mars in forms different from on the Earth, and in much larger amounts, and we guessed that they would be important to the fate of manganese.”
The scientists, however, stress that although oxygen may not have been present in Mars’ ancient atmosphere after all, the planet still could have teemed with microscopic life forms in the past.
“There are several life forms even on Earth that do not require oxygen to survive,” Mitra said. “I don’t think of it as a ‘setback’ to habitability — only that there was probably no oxygen-based lifeforms.”
The study (opens in new tab) was published on Thursday (Dec. 22), in the journal Nature Geoscience.
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Map of especially metal-poor giant stars identified from Gaia DR3 data that shows, as a concentrated region (marked with a circke), the stars of the “poor old heart” of the Milky Way galaxy. The map shows the whole of the night sky in the same way that certain maps of the world show Earth’s surface. In the center of the map is the direction towards the center of our home galaxy. Credit: H.-W. Rix / MPIA
A group of MPIA astronomers has managed to identify the “poor old heart of the Milky Way”—a population of stars left over from the earliest history of our home galaxy, which resides in our galaxy’s core regions.
For this feat of “galactic archaeology,” the researchers analyzed data from the most recent release of ESA’s Gaia Mission, using a neural network to extract metallicities for two million bright giant stars in the inner region of our galaxy. The detection of these stars, but also their observed properties, provides welcome corroboration for cosmological simulations of the earliest history of our home galaxy.
Our home galaxy, the Milky Way, gradually formed over nearly the entire history of the universe, which spans 13 billion years. Over the past decades, astronomers have managed to reconstruct different epochs of galactic history in the same way that archaeologists would reconstruct the history of a city: Some buildings come with explicit dates of construction.
For others, the use of more primitive building materials or older building styles implies that they have come before, as does the situation where remnants are found underneath other (and thus newer) structures. Last but not least, spatial patterns are important—for many cities, there will be a central old town surrounded by districts that are clearly newer.
For galaxies, and in particular for our home galaxy, cosmic archaeology proceeds along very similar lines. The basic building blocks of a galaxy are its stars. For a small subset of stars, astronomers can deduce precisely how old they are. For example, this is true for so-called sub-giants, a brief phase of stellar evolution where a star’s brightness and temperature can be used to deduce its age.
Estimating age from chemistry
More generally, for almost all stars, there is a “building style” that allows a general verdict on age: a star’s so-called metallicity, defined as the amount of chemical elements heavier than helium that the star’s atmosphere contains. Such elements, which astronomers call “metals,” are produced inside stars through nuclear fusion and released near or at the end of a star’s life—some when a low-mass star’s atmosphere disperses, the heavier elements more violently when a high-mass star explodes as a supernova. In this way, each generation of stars “seeds” the interstellar gas from which the next generation of stars is formed, and generally, each generation will have a higher metallicity than the rest.
As for larger-scale structures, just like in a city, spatial distribution matters. But given that a galaxy is less static than a city—buildings do not usually move around, while stars do—motion patterns encode important information as well. Milky Way stars may be confined to the central regions, or they may be part of an orderly rotating motion in the Milky Way’s thin disk or thick disk. Or else, they may form part of the chaotic jumble of orbits of our galaxy’s extended halo of stars—including very eccentric ones, which repeatedly plunge through the inner and outermost regions.
How large galaxies grow over time
Where cities might undergo construction booms or periods of intensive remodeling, galaxy history is shaped by mergers and collisions, as well as by the vast amounts of fresh hydrogen gas that flow into galaxies over billions of years, the raw material for a galaxy to make new stars. A galaxy’s history starts with smaller proto-galaxies: over-dense regions shortly after the Big Bang, where gas clouds collapse to form stars.
As such, proto-galaxies collide and merge, they form larger galaxies. Add another proto-galaxy to these somewhat larger objects, namely a proto-galaxy that flies in sufficiently off-center (“large orbital angular momentum”), and you may end up with a disk of stars. Merge two sufficiently large galaxies (“major merger”), and their gas reservoirs will heat up, forming a complicated elliptical galaxy combining a dearth of new star formation with a complex pattern of orbits for the existing older stars.
Reconstructing this kind of history is a matter of combining ever-more informative observations with ever-more sophisticated simulations. And while the general picture of what happens as galaxies form and evolve has been around for a number of decades, the specifics have only emerged comparatively recently—thanks in large part to surveys that have yielded better and more comprehensive data.
Our home galaxy, the Milky Way, plays a special role in this. By definition, this is the galaxy whose stars we can examine best and in the most detailed way. Galactic archaeology, defined as the study of the history of our home galaxy, not only allows us to reconstruct parts of our own wider history but also to learn something about galaxy evolution in general (“local cosmology”).
What came before the Milky Way’s exciting teenage years?
This particular episode of galactic archaeology began with a reconstruction published in Spring 2022: MPIA researchers Maosheng Xiang and Hans-Walter Rix had made use of data from ESA’s Gaia satellite and from the LAMOST spectral survey to determine the ages of stars in an unprecedented sample of 250,000 so-called sub-giants. From this analysis, the astronomers had been able to reconstruct the consequences of the Milky Way’s exciting teenage years 11 billion years ago and its subsequent more settled (or boring) adulthood.
(The teenage years coincided with the last significant merger of another galaxy, called Gaia Enceladus/Sausage, whose remnants were found in 2018, with the Milky Way. It sparked a phase of intensive star formation and led to a comparatively thick disk of stars we can see today. Adulthood consisted of a moderate inflow of hydrogen gas, which settled into our galaxy’s extended thin disk, with the slow, but the continual formation of new stars over billions of years.)
What the astronomers noticed back then was that the oldest stars in their teenage sample already had considerable metallicity, about 10% as much as the metallicity of our sun. Clearly, before those stars formed, there must have been even earlier generations of stars that had polluted the interstellar medium with metals.
What simulations tell us about the Milky Way’s ancient core
In fact, the existence of those earlier generations was in line with the predictions from simulations of cosmic history. And furthermore, those simulations predicted where surviving representatives of those earlier generations might reasonably be found. Specifically, in these simulations, the initial formation of what later became our Milky Way involved three or four proto-galaxies that had formed in close proximity and then merged with each other, their stars settling down as a comparatively compact core, no more than a few thousand light-years in diameter.
Later additions of smaller galaxies would lead to the creation of the various disk structures and the halo. But according to the simulations, part of that initial core could be expected to survive these later developments relatively unscathed. It should be possible to find stars from the initial compact core, the ancient heart of the Milky Way, in and near the central regions of our galaxy even today, billions of years later.
In search of ancient core stars
At this point, Rix became interested in ways to actually find stars from our galaxy’s ancient core. But he knew that to come up with more than a few dozen such stars, he would need a new observing strategy. The LAMOST telescope used in the previous study, due to its location on Earth and its inability to observe during the monsoon months in summer, cannot observe the Milky Way’s core regions at all. And sub-giants, as the previous probe of choice, are much too dim to be observable beyond distances of about 7,000 light-years, putting the core regions of our galaxy squarely out of reach.
Recall that in addition to those rare stars where we can determine specific ages, there is the much more general indicator of stellar metallicity—the “varying building styles” that allow one to sort stars into older and younger. Happily, in June 2022 came the Data Release 3 (DR3) of ESA’s Gaia mission. Since 2014, Gaia has been measuring highly accurate position and motion parameters, including distances, for more than a billion stars, revolutionizing (among other sub-fields) galactic astronomy. DR3 was the first data release to include some of the actual spectra Gaia had observed: spectra for 220 million astronomical objects.
Red giants from Gaia
Spectra are where astronomers find information about the chemical composition of a star’s atmosphere, including metallicity. But while Gaia’s spectra are of high quality, and there is an unrivaled number of them, the spectral resolution—how finely the light of an object is split by wavelength into the elementary rainbow colors—is comparatively low by design. Extracting reliable metallicity values from the Gaia data would require extra analysis, and this is what Hans-Walter Rix and René Andrae, a Gaia researcher at MPIA, tackled in a project with their visiting summer student Vedant Chandra from Harvard University.
Since they knew their analysis needed to reach the core regions of the Milky Way, the three astronomers specifically looked at red giant stars in the Gaia sample. Typical red giants are about a hundred times brighter than sub-giants and readily observable even in the distant core regions of our galaxy. These stars also have the added advantage that the spectral features that encode their metallicity are comparatively conspicuous, making them particularly suitable for the kind of analysis the astronomers were planning.
Extracting metallicities with machine learning
For the analysis itself, the astronomers turned to machine learning methods. By now, many people will have come across applications of this innovative technique: software like DALL-E that generates suitable images from simple textual descriptions, or ChatGPT that can more-or-less competently answer questions and fulfill writing requests. The key property of machine learning is that the solution strategies are not programmed explicitly. Instead, at the core of the algorithm is a so-called neural network, with superficial similarities to the way that neurons are arranged in human brains. That neural network is then trained: given combinations of tasks and their solutions, and the connections between input and output adjusted so that, for the training set at least, the network produces the correct output given a specific input.
In this specific case, the neural network was trained using selected Gaia spectra as an input—specifically: Gaia spectra for which the right answer, the metallicity, was already known from another survey (APOGEE, high-resolution spectral observations as part of the Sloan Digital Sky Survey [SDSS]). The network’s internal structure adapted so that, for the training set at least, it could reproduce the correct metallicities.
Reliable metallicities for 2 million bright giants
A general challenge in using machine learning in science is that, by its very nature, the neural network is a “black box”—its internal structure has been formed by the training process and is not under the direct control of the scientists. That is why, to start with, Andrae, Chandra, and Rix trained their neural network only on half of the APOGEE data. In a second step, the algorithm was then set to prove its worth against the rest of the APOGEE data—with spectacular results: the neural network was able to deduce precise and accurate metallicities even for stars it had never encountered before.
Now that the researchers had not only trained their neural network but also ensured that it could obtain precise results for spectra it had not encountered during its training, the researchers applied the algorithm to their full red giant data set of Gaia spectra. Once the results were in, the researchers had access to a sample of accurate metallicities of unprecedented size, consisting of 2 million bright giants in the inner galaxy.
Mapping the ancient heart of the Milky Way
With that sample, it proved comparatively easy to identify the ancient heart of the Milky Way galaxy—a population of stars that Rix has dubbed the “poor old heart,” given their low metallicity, inferred old age, and central location. On a sky map, these stars appear to be concentrated around the galactic center. The distances conveniently supplied by Gaia (via the parallax method) allow for a 3D reconstruction that shows those stars confined within a comparatively small region around the center, approximately 30,000 light-years across
The stars in question neatly complement Xiang’s and Rix’s earlier study of the Milky Way’s teenage years: They have just the right metallicity to have brought forth the metal-poorest of those stars that, later on, formed the Milky Way’s thick disk. Since that earlier study provided a chronology for thick-disk formation, this makes the ancient heart of the Milky Way older than about 12.5 billion years.
Corroboration from chemistry
For the small subset of objects for which APOGEE spectra are available, it is possible to go one step further: These spectra yield additional properties of the poor-old-heart stars in this subset, specifically the abundance of elements like oxygen, silicon, and neon. Those elements can be obtained by successively adding alpha particles (helium-4 nuclei) to existing nuclei in a process called “alpha enhancement.” Their presence in such quantities indicates that the early stars obtained their metals from an environment in which heavier elements were produced on comparatively short time scales via the supernova explosions of massive stars.
This is much more consistent with these stars having formed directly after the first few proto-galaxies had merged to form the Milky Way’s initial core, rather than having already been present in the dwarf galaxies that formed the Milky Way’s initial core or that merged with the Milky Way afterward. It constitutes yet another corroboration of what cosmological simulations have to say about the earliest history of our home galaxy.
A path to finding the Milky Way’s progenitor galaxies?
While the information obtained from Gaia’s global view is ground-breaking in demonstrating the continued existence of our Milky Way’s “poor old heart,” that discovery immediately makes astronomers want to learn more: Can one obtain more detailed spectra for many more or even all of those stars, which allow for a more detailed analysis of their chemical composition? Will they all show alpha enhancement, consistent with their formation in the Milky Way’s initial core? Follow-up spectra taken as part of the recently launched SDSS-V survey or the upcoming 4MOST survey, in both of which MPIA is a partner, promise to allow the group to obtain the information necessary for answering these key questions.
If things go exceptionally well, the additional data might even allow the researchers to identify which stars in the core region belong to which of the Milky Way’s progenitor galaxies: For an older star, like those in the poor old heart, the additional data about chemical composition and temperature allows for a reliable estimate of the star’s luminosity. By comparison with how bright that star is in the sky, one can deduce the star’s distance—the farther away a star is, the dimmer it will appear to us. For the comparatively distant stars in question, distance values obtained in this way are considerably more precise than the results of Gaia’s parallax measurements.
The combination of a star’s position in the sky and its distance gives us the star’s three-dimensional location within the Milky Way. The information about the stars’ motion towards or away from us—measured by the Doppler shift of their spectral lines—combined with their apparent motions on the sky permits the reconstruction of the stars’ orbits within our home galaxy. If such an analysis shows that the stars of the poor old heart belong to two or three different groups, each with its own pattern of motion, those groups are likely to correspond to the different two or three progenitor galaxies whose initial merger created the archaic Milky Way.
The results described here have been published as Hans-Walter Rix et al, “The Poor Old Heart of the Milky Way,” in the Astrophysical Journal.
More information:
Hans-Walter Rix et al, The Poor Old Heart of the Milky Way, The Astrophysical Journal (2022). DOI: 10.3847/1538-4357/ac9e01
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Astronomers identify the ancient heart of the Milky Way galaxy (2022, December 20)
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