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What is a mass extinction, and why do scientists think we’re in the middle of one?

ination online — Mon, 09 Sep 2024 11:59:32 +0000

No species lasts forever — extinction is part of the evolution of life.

But at least five times, a biological catastrophe has engulfed the planet, killing off the vast majority of species from water and land over a relatively short geological interval.

The most famous of these mass extinction events — when an asteroid slammed into Earth 66 million years ago, dooming the dinosaurs and many other species — is also the most recent. But scientists say it won’t be the last.

Many researchers argue we’re in the middle of a sixth mass extinction, caused not by a city-size space rock but by the overgrowth and transformative behavior of a single species — Homo sapiens. Humans have destroyed habitats and unleashed a climate crisis.

Calculations in a September study published in the journal PNAS have suggested that groups of related animal species are disappearing at a rate 35% times higher than the normally expected rate.

And while every mass extinction has winners and losers, there is no reason to assume that human beings in this case would be among the survivors.

In fact, study coauthor Gerardo Ceballos thinks the opposite could come to pass, with the sixth mass extinction transforming the whole biosphere, or the area of the world hospitable to life — possibly into a state in which it may be impossible for humanity to persist unless dramatic action is taken.

“Biodiversity will recover but the winners (are) very difficult to predict. Many of the losers in these past mass extinctions were incredibly successful groups,” said Ceballos, a senior researcher at the Institute of Ecology at the National Autonomous University of Mexico.

While the causes of the “big five” mass extinctions varied, understanding what happened during these dramatic chapters in Earth’s history — and what emerged in the aftermath of these cataclysms — can be instructive.

“Nobody’s seen these events but they’re on a scale that might be repeated. We’ve got … (to) learn from the past because that’s our only data set,” said Michael Benton, a professor of vertebrate paleontology at Bristol University in the United Kingdom who is the author of the new book “Extinctions: How Life Survives, Adapts and Evolves.”

A really bad day: Dino-killing asteroid and the iridium anomaly

While paleontologists have studied fossils for centuries, the science of mass extinction is relatively new. Radiometric dating, based on the natural radioactive decay of certain elements, like carbon, and other techniques revolutionized the ability to precisely determine the age of ancient rocks in the second half of the last century.

The developments set the stage for the work of the late Nobel Prize-winning physicist Luis Alvarez and his geologist son Walter, professor of Earth and planetary science at the Univeristy of California, Berkeley. Along with two other colleagues, they coauthored a sensational 1980 paper about the “iridium anomaly” — a 1-centimeter-thick (0.4-inch-thick) layer of sedimentary rock rich in iridium, an element rare on Earth’s surface but common in meteorites.

The researchers attributed the anomaly, which they initially identified in Italy, Denmark and New Zealand, to the impact of a large asteroid. They argued the unusual layer represented the exact moment in time when dinosaurs disappeared.

First met with skepticism, the iridium anomaly eventually was spotted in more and more places around the world. A decade later, a different group of researchers identified the smoking gun: a 200-kilometer-wide (125-mile-wide) crater off the coast of Mexico’s Yucatan Peninsula.

The rock and sediment there had a similar composition to the iridium layers, and the scientists suggested the depression, called the Chicxulub crater, was caused by the impact of an asteroid. Researchers believe the other anomalies spotted across the globe were caused by scattering debris when the space rock struck Earth.

Most paleontologists now accept that the asteroid caused what’s known as the end-Cretaceous extinction. The strike triggered a period of global cooling, with dust, soot and sulfur thrown up during the impact blocking the sun and likely shutting down photosynthesis, a key process for life.

One fossil site in North Dakota has provided an unprecedented level of detail on what that day — and its immediate aftermath — was like. Debris rained down, lodging itself into the gills of fish, while huge tsunami-like surges of water unleashed by the strike killed dinosaurs and other creatures. Scientists have even figured out that the asteroid smashed into Earth in springtime.

The disappearance of massive dinosaurs created a world in which mammals — and ultimately humans — were able to thrive. And dinosaurs weren’t the total losers they are sometimes made out to be: Scientists now believe that the birds that flap around in our backyards directly evolved from smaller relatives of Tyrannosaurus rex.

In the wake of the Alvarez duo’s stunning discovery, it initially seemed to scientists as if a space rock impact might be a general mechanism that explained all mass extinction events identified in the geological record. But the end-Cretaceous extinction is the only one reliably associated with an asteroid, according to Benton.

A different culprit, however, does explain several smaller extinction episodes and at least two mass extinctions, including the largest on record.

Apocalyptic volcanoes that caused global warming

Something known as a hyperthermal event — a sudden warming of the planet — spelled doom for large segments of life on Earth on more than one occasion. These events have followed a predictable pattern: volcanic eruption, carbon dioxide release, global warming, acid rain, ocean acidification — resulting in a longer road to oblivion than the dino-killing asteroid but equally destructive.

The biggest mass cataclysm of all time, called the end-Permian extinction, occurred 252 million years ago. Some 95% of species disappeared on land and at sea as a result of global warming — with temperatures rising perhaps 10 degrees Celsius to 15 degrees Celsius (18 F to 27 F), Benton noted in his book.

Known as “the Great Dying,” the extinction event was marked by supervolcanic eruptions that expelled greenhouse gases in an Australia-size region known as the Siberian Traps in Eurasia. That led to extreme acid rain that killed plant life and left the land surface rocky as the precipitation washed rich soil into the oceans, which in turn became swamped with organic matter, Benton explained.

However, into the void that followed emerged different creatures that evolved from the survivors, displaying many new ways of existence with features such as feathers, hair and speedy locomotion, Benton said.

“One of the big changes … on land, it seems, was a great rise in energy of everything,” he explained. “All of the surviving reptiles very rapidly became upright in posture instead of (low and) sprawling. (Some animals) became warm blooded in some way because we track feathers back to the early Triassic dinosaurs and their nearest relatives, and on the mammals side, we track the origin of hair.”

When dinosaurs got big

Another period of extreme volcanic activity 201 million years ago marked the end-Triassic mass extinction. It has been linked to the breakup of the Pangea supercontinent and the opening of the central Atlantic Ocean. Many land reptiles vanished as a result of that catastrophic event, making way for the towering sauropods and armored plant eaters commonly seen in childhood dinosaur books.

“The dinosaurs were already around but they had not fully diversified,” Benton said. “And then in the early Jurassic, … the dinosaurs really took off.”

Deeper in time, a mass extinction event that ended the Devonian Period, a geological era when life thrived on land for the first time, was also attributed to a hyperthermal event likely triggered by volcanic activity 359 million years ago, according to Benton’s book.

Other research published in 2020 suggested that multiple star explosions — known as supernovae — may have played a role.

A less well-understood period of worldwide cooling soon followed. It’s thought that these twin crises — separated by only 14 million years — led to rapid changes in temperature and sea level that resulted in the loss of at least 50% of the world’s species, wiping out many armored fish, early land plants, and animals such as the fishapods, or the earliest elpistostegalians, that were making the transition from water to land.

The resulting loss of marine species made way for the golden age of sharks during the Carboniferous Period, when the predators dominated the seas and evolved to include a variety of species with different forms.

Sinking temperatures and sea levels

Colder temperatures and a drastic drop in sea levels — perhaps as much as 10 degrees Celsius (18 F) cooler and 150 meters (492 feet) lower, respectively — played a major role in the earliest identified mass extinction event, the end-Ordovician, according to Benton. That shift, which took place about 444 million years ago, led to the disappearance of 80% of species at a time when life was mostly limited to the seas.

What triggered the die-off was the massive Gondwana supercontinent (today’s South America, Africa, Antarctica and Australia) drifting over the South Pole during the Ordovician. When a land mass covers the polar region, the ice cap reflects sunlight and slows melting, resulting in an expanding ice cap that lowers sea levels globally.

Adding to the cataclysm was volcanic activity. However, in this case, it did not appear to make global temperatures warmer. Instead, phosphorus from lava and volcanic rocks washed into the sea, gobbling up life-giving oxygen from the oceans.

The looming sixth mass extinction

A growing number of scientists believe a sixth mass extinction event of a magnitude equal to the prior five has been unfolding for the past 10,000 years as humans have made their mark around the globe.

The dodo, the Tasmanian tiger, the baiji, or Yangtze River dolphin, and the Western black rhino are just a few of the species that have disappeared so far in what’s known as the Holocene or Anthropocene extinction.

While the loss of even one species is devastating, Ceballos of the National Autonomous University of Mexico has highlighted that the ongoing episode of extinction is mutilating much thicker branches of the tree of life, a metaphor and model that groups living entities and maps their evolutionary relationships.

Entire categories of related species, or genera, are disappearing, a process he said is affecting whole ecosystems and endangering the survival of our own species.

Ceballos and his study coauthor Paul Ehrlich, Bing Professor Emeritus of Population Studies at Stanford University, assessed 5,400 genera of vertebrate animals, excluding fishes. A single genus groups one or more different but related species — for example the genus Canis includes wolves, dogs, coyotes and jackals.

The duo’s analysis found that 73 genera had gone extinct in the past 500 years. This is much faster than the expected “background” extinction rate, or the rate at which species would naturally die off without outside influence — in the absence of human beings, these 73 genera would have taken 18,000 years to vanish, the researchers said.

The causes of these extinctions are varied — land-use change, habitat loss, deforestation, intensive farming and agriculture, invasive species, overhunting and the climate crisis — but all these devastating changes have a common thread: humanity.

Ceballos pointed to the extinction of the passenger pigeon, which was the only species in its genus, as an example of how losing a genus can have a cascading effect on a wider ecosystem. The bird’s loss, a result of reckless hunting in the 19th century, narrowed human diets in eastern North America and allowed the bacteria-harboring White-footed mice that were among its prey to thrive.

What’s more, some scientists believe the passenger pigeon’s extinction, combined with other factors, is behind today’s rise of tick-borne diseases such as Lyme disease that plague humans and animals alike, according to the study.

Not only do the destructive actions of humans have the potential to erode our quality of life in the long term, but their ripple effects could eventually upend our success as a species, according to Ceballos.

“When we lose genera, we’re losing more genetic diversity, we’re losing more evolutionary history, and we’re losing (many) more ecosystem goods and services that are very important,” he explained.

While branches of the tree of life are vanishing, the distribution of certain animal species is becoming more homogenized — the world is home to about 19.6 billion chickens, 980 million pigs and 1.4 billion cattle. In some cases, intensive farming can trigger outbreaks of disease like avian influenza outbreaks that rip through poultry farms and increase risk of spillover in wild migratory birds. Other farm animals act as hosts for virus that infect humans, with the potential to cause pandemics like Covid-19.

Ultimately, the planet can and will survive just fine without us, Ceballos added. But, like the iridium anomaly left by the dinosaur-dooming space rock, what might the final traces of human civilization look like in the geological record?

Some scientists point to the geochemical traces of nuclear bomb tests, specifically plutonium — a radioactive element widely detected across the world in coral reefs, ice cores and peat bogs.

Others say it could be something altogether more mundane, such as a fossilized layer of bones from chickens — the domesticated bird industrially bred and consumed across the world in mammoth quantities — that’s left as humanity’s defining legacy for the ages.

The post What is a mass extinction, and why do scientists think we’re in the middle of one? appeared first on Ination.

The remarkable fossil that radically changed our understanding of the human story

ination online — Mon, 09 Sep 2024 11:49:57 +0000

Indonesian archaeologist Thomas Sutikna was nursing a fever in a hotel room on September 2, 2003, when a coworker shared news of what turned out to be a once-in-a-generation discovery.

Earlier that day, a colleague’s trowel had hit a tiny human-like skull encased in 6-meter (19.7-foot) deep sediment in Liang Bua, a large cave in the highlands of the Indonesian island of Flores that Sutikna and his colleagues had been excavating since 2001. Sutikna’s fever immediately vanished, and after a fitful night’s sleep, he and his team set off for the site at sunrise.

They were thrilled to uncover more bones — some still attached to one another — in the same location at the high-ceilinged cave.

“There were leg bones, hand bones, tibia, femur, grouped in there, in one context.
Given the very fragile condition of the bone, it was not possible to lift it (out of the ground) immediately,” recalled Sutikna, now an archaeologist and researcher at Indonesia’s Center for Archaeometric Research at the country’s National Research and Innovation Agency.

To harden the brittle exposed bone, he applied some acetone nail polish remover bought from a cosmetics store mixed with glue the team had on site.
The team then brought the blocks of cut sediment containing the bones back to the hotel by minibus.

Wahyu Saptomo, one of the field archaeologists who had first told Sutikna about the discovery, remembered that they placed the blocks of soil on their laps — the safest place during a bumpy minibus ride on an unpaved road.

At first, the team thought perhaps the tiny skull and other bones belonged to a child, but as Sutikna cleaned the fossil at the hotel, he saw it had the molar teeth of an adult. It appeared to be a completely new kind of human, a female specimen with a perplexing combination of features that stood just over 3 feet (about 1 meter tall) and would have weighed around 66 pounds (30 kilograms).

“We were all surprised by the fossil, because after cleaning it could be seen that the teeth had all grown and were intact. The skull bones also showed that it was an adult bone, not a child’s skull,” said Sutikna, who subsequently took the fossil to Jakarta, the Indonesian capital.

Now, 20 years later, scientists are still struggling to definitively place this enigmatic piece of the evolutionary puzzle. But the journey sparked by its discovery has led to revelations that challenge what’s known about the human family tree.

Explosive discovery

The team and its international collaborators knew from the start that what they had found was groundbreaking, and they worked hard to keep their discovery secret for more than a year so the remains could be studied in detail.

When they released the results of their research, in two studies published in the high-profile scientific journal Nature just over a year later, the findings shook up the field of paleoanthropology and captivated a wider audience, making headlines around the world.

Nicknamed hobbit — the massively popular first “Lord of the Rings” film had come out in late 2001 — by Mike Morwood, the late Australian archaeologist who had spearheaded the dig, the Liang Bua specimen looked like something from the movie’s Middle Earth realm.

The volume of its braincase, measured with mustard seeds smuggled from Australia through Indonesian customs, was around 400 milliliters, similar to a chimpanzee. (The volume of a modern human braincase is 1,500 milliliters.) Its legs were short, with disproportionately large feet, and its arms long like a primate.

Initial dating of carbon in the sediment determined the remains to be 18,000 years old, which was startlingly young, putting the previously unknown species closer in time to us than the Neanderthals. (The dates were revised in 2016, estimating instead that the hobbit was 50,000 to 60,000 years old.)

The Liang Bua team named the species Homo floresiensis after the island where the fossils were discovered. (Two other names were considered: Homo hobbitus — passed over because it was thought to trivialize the find — and floresianus — rejected after the realization that it meant flowery anus.)

The discovery challenged the idea that humans evolved in a neat line from primitive to complex and underscored just how much remained unknown about the human story.

“(The specimen) was just wrong in about five different ways and unexpected to the point of people thinking like this can’t be possible,” said Paige Madison, a historian of paleoanthropology and science writer who is working on a book about the hobbit titled “Strange Creatures Beyond Count” to be published in 2025

How the hobbit came to be

Some experts in human evolution vehemently argued the Liang Bua bones were those of a modern human with a growth disorder — such as microcephaly, a condition that leads to an abnormally small head, a small body and some cognitive impairment. That assertion unleashed a fierce debate that took years to resolve.

The team that discovered the hobbit disagreed and put forward two theories. Most likely, members of the team thought, their find was a dwarfed offshoot of Homo erectus — the first human species to leave Africa and migrate around the world, the remains of which have been discovered in Java and elsewhere in Asia.

The shape of the teeth and skull morphology were similar, though Homo erectus stood much taller. It was possible, the researchers thought, that Homo erectus had done what some other species of animals that live on remote islands have — shrunk over time in response to limited resources.

However, the tiny brain case and chimplike wristbones suggested the hobbit was related to australopithecines — small-bodied hominins, best known from the famous Lucy fossil, that roamed Africa more than 2 million years ago. This potential link raised the possibility that australopithecines also once migrated out of Africa millions of years ago.

Exactly how the hobbit came to be is still an open question, said Chris Stringer, research leader in human evolution at the Natural History Museum in London.

“I’m on the fence on this one because I can see the evidence for both sides of the argument,” Stringer said, “and I think we really still don’t know where its origins are.”

However, the idea that the hobbit was a diseased modern human has been largely rejected, he said.

The subsequent discovery of two other small-bodied and small-brained hominins that lived relatively recently — Homo naledi in South Africa and Homo luzonensis in the Philippines — and the much larger Denisovans has led to a wider acceptance among paleoanthropologists that there have been many, diverse species of human, including several that coexisted with our own species, Homo sapiens. Before the discovery of the hobbit, many experts in human evolution thought essentially only one species of human had evolved through time, with regional variation.

‘So many unknowns’

Matt Tocheri, Canada research chair in human origins at Lakehead University in Thunder Bay, Ontario, first saw casts of the Liang Bua hobbit around 2006 during a presentation on the fossils’ conservation at the Smithsonian Institution. An expert in wristbone evolution, he was immediately stunned to see that the wrists more closely resembled those of an African ape than a human, an observation that swayed him toward the idea that Homo floresiensis is more closely connected to Lucy and her relatives than a scaled-down Homo erectus.

In 2014, a partial Homo floresiensis jawbone and teeth were found on a different site on Flores called Mata Menge and dated to 700,000 years ago — considerably older than the original specimen. They were similar in size, if not smaller, than those found in Liang Bua, suggesting that the Flores hobbits had acquired their extremely small body size by that early point, working against the idea that the hobbits were evolutionary dwarfs of some kind.

However, other experts argue that dwarfism could have happened even deeper in the past or on a different island.

It’s also possible, Tocheri noted, that the hobbit’s small stature is a result of sexual dimorphism — when the two sexes have different physical characteristics. The working hypothesis is that the Liang Bua hobbit is female because of the broader shape of its pelvis, and it’s not clear what a male hobbit might have looked like. While more than 100 Homo floresiensis fossils — likely belonging to six or seven individuals — have been unearthed to date, there’s only one relatively complete skeleton and only one skull, which is the most informative body part.

Tocheri, who is now closely involved with archaeological work on Flores, keeps an open mind. “There are still so many unknowns; we have to be very careful,” he said.

To resolve these debates and understand more about Homo floresiensis and its place in the human family tree, more fossil discoveries are needed, particularly in Asia. For example, Tocheri noted, there are no known Homo erectus wristbones for him to compare with the hobbit’s.

Scientists also hope to be able extract ancient DNA from Liang Bua. Attempts so far have been unsuccessful, but new techniques — including extracting DNA from cave dirt or decoding ancient proteins — could help shed light on which hominin the hobbit is most closely related to.

“They see it as kind of like a holy grail of genomes,” said Madison, the science writer. “It seems that the hobbit is probably at the edge of possibility as far as recovering a genome. Not because it’s too old, because they have genomes much older, but because the environmental conditions are so important in preserving that (DNA). And those hot environments, humid environments, those are really difficult environments for them to retrieve DNA.”

Homo floresiensis: A ‘whole other chapter’

There’s still much to learn about the hobbit. Sutikna marvels at how such a primitive-looking hominin might have reached Flores: Only Homo sapiens were thought to be able to make oceangoing vessels, and Flores has never been connected to a large landmass, so ancient humans couldn’t have walked there.

The study of ocean currents suggests that the species might have come from Sulawesi, an island to the north, rather than the closer islands to the west, although Homo floresiensis fossils have still only been found on Flores. Stringer said he thinks it’s possible that a group of hobbits was swept on a raft of land in the aftermath of a tsunami.

Archaeologists and paleontologists have also pieced together some information about the hobbits’ lives. Their island was home to a now-lost ecosystem of dwarfed elephants called stegodons that stood 1.2 meters (3.9 feet) high, colossal 2-meter-tall (6.6-foot-tall) storks, Komodo dragons and giant rats.

It’s not clear whether the hobbits would have hunted or scavenged these animals, although Tocheri said it was most likely the latter given the hobbits’ size. While charcoal has been found in the cave, it’s now thought that this evidence of fire use is associated with the later occupancy of modern humans, rather than the hobbits.

Another mystery is why the hobbits disappeared after surviving for so long on Flores. Sutikna said that a thick layer of volcanic ash was found just on top of the layer where Homo floresiensis was first found.

“We estimate that at least eight volcanic eruptions have occurred. And above the volcanic ash layer, we did not find any fossils of Homo floresiensis or other ancient animals,” he said. “However, we cannot confirm whether this natural disaster destroyed Homo floresiensis.”

Tocheri said it’s unlikely that a volcano alone doomed the hobbits. The island of Flores had always been volcanically active, and the hobbit had lived there for the nearly 1 million years. More likely, it was a combination of factors. A changing climate, perhaps combined with the arrival of Homo sapiens in the region, could have played a role, Tocheri said.

Whatever led to its extinction, the hobbit’s discovery teaches us about humanity’s place in the evolutionary tree and nature more broadly, according to Madison.

“We know a lot about evolutionary principles at this point, but sometimes I think we’re a little bit hesitant to apply them to ourselves,” Madison said. “I think that (this discovery) reminds us that we’re just one evolutionary outcome.”

Tocheri agreed. “It didn’t really rewrite what we knew, but it just explosively showed us that there was this whole other chapter.”

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Scientists reveal the face of a Neanderthal who lived 75,000 years ago

ination online — Mon, 09 Sep 2024 11:43:44 +0000

A 40-something woman was buried in a cave 75,000 years ago, laid to rest in a gully hollowed out to accommodate her body. Her left hand was curled under her head, and a rock behind her head may have been placed as a cushion.

Known as Shanidar Z, after the cave in Iraqi Kurdistan where she was found in 2018, the woman was a Neanderthal, a type of ancient human that disappeared around 40,000 years ago.

Scientists studying her remains have painstakingly pieced together her skull from 200 bone fragments, a process that took nine months. They used the contours of the face and skull to guide a reconstruction to understand what she may have looked like.
The striking recreation is featured in a new documentary “Secrets of the Neanderthals” produced by BBC for Netflix, which is available for streaming on Thursday.

With pronounced brow ridges and no chins, the skulls of Neanderthals look different from those of our own species, Homo sapiens, said Dr. Emma Pomeroy, a paleoanthropologist and associate professor with the University of Cambridge’s department of archaeology who unearthed the skeleton and appears in the new film. The Shanidar Z facial reconstruction suggests that these differences might not have been so stark in life, Pomeroy said.

“There is some artistic license there, but at the heart of it is the real skull and real data on what we know about (these) people,” she said.

“She’s actually got quite a large face for her size,” Pomeroy added. “She’s got quite big brow ridges, which typically we wouldn’t see, but I think dressed in modern clothes you probably wouldn’t look twice.”

New analysis

When Pomeroy first excavated the skeleton, its sex wasn’t immediately obvious because only the upper half of the body was preserved. It lacked telltale pelvic bones. The team that initially studied the remains relied on a relatively new technique involving the sequencing of proteins inside tooth enamel to determine Shanidar Z’s sex, which is revealed for the first time in the documentary.

Those researchers from the universities of Cambridge and Liverpool estimated the specimen’s height to have been around 5 feet (1.5 meters) by comparing the length and diameter of her arm bones with data on modern humans. An analysis of wear and tear on teeth and bones suggested she was in her mid-40s at the time of her death.

“It’s a reasonable estimate, but we can’t be 100% sure, actually, that they weren’t older,” Pomeroy said. “What we can say is this is someone who had lived a relatively long life. For that society, they probably would have been quite important in terms of their knowledge, their life experience.”

The cave where Shanidar Z was buried is well-known among archaeologists because a Neanderthal grave discovered there in 1960 led researchers to believe that Neanderthals may have interred their dead with flowers — the first challenge to the prevailing view that the ancient humans were dumb and brutish. Subsequent research by Pomeroy’s team, however, has cast doubt on that flower burial theory.
Instead, they suspect the pollen discovered among the graves may have arrived via pollinating bees.

Still, over the years scientists have found increasing evidence of Neanderthals’ intelligence, sophistication and complexity, including art , string and tools.

Neanderthals repeatedly returned to Shanidar Cave to lay their dead to rest. The remains of 10 Neanderthals have been unearthed at the site, half of which appear to have been buried deliberately in succession, research has found.

Neanderthals may not have honored their dead with bouquets of flowers, but the inhabitants of Shanidar Cave were likely an empathetic species, research suggests. For example, one male Neanderthal buried there was deaf and had a paralyzed arm and head trauma that probably rendered him partially blind, yet he lived a long time, so he must have been cared for, according to research.

Shanidar Z is the first Neanderthal found in the cave in more than 50 years, Pomeroy said, but the site could still yield more discoveries. During the filming of the documentary in 2022, Pomeroy uncovered a left shoulder blade, some rib bones and a right hand belonging to another Neanderthal.

“I think our interpretation at the moment,” she said, “is that actually this is probably the remains of a single individual, which has then been disturbed.”

Reconstructing the skull

Pomeroy described reconstructing Shanidar Z’s skull, which had been crushed relatively soon after death as a “high-stakes 3D jigsaw puzzle.” The fossilized bones were hardened with a glue-like substance, removed in small blocks of cave sediment and wrapped in foil before researchers sent them to the University of Cambridge for analysis.

In the Cambridge lab, researchers took micro-CT scans of each block and used the scans to guide extraction of bone fragments. Pomeroy’s colleague Dr. Lucía López-Polín, an archaeological conservator from the Catalan Institute for Human Palaeoecology and Social Evolution in Spain, pieced over 200 bits of skull together by eye to return it to its original shape.

The team scanned and 3D-printed the rebuilt skull, which formed the basis of a reconstructed head created by Dutch paleoartists Adrie and Alfons Kennis, twin brothers who built up layers of fabricated muscle and skin to reveal Shanidar Z’s face.

Pomeroy said the reconstruction helped “bridge that gap between anatomy and 75,000 years of time.”

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Last letters of pioneering climber who died on Everest reveal dark side of mountaineering

ination online — Mon, 09 Sep 2024 11:38:20 +0000

George Mallory is renowned for being one of the first British mountaineers to attempt to scale the dizzying heights of Mount Everest during the 1920s — until the mountain claimed his life.

Nearly a century later, newly digitized letters shed light on Mallory’s hopes and fears about ascending Everest, leading up to the last days before he disappeared while heading for its peak.

On June 8, 1924, Mallory and fellow climber Andrew Irvine departed from their expedition team in a push for the summit; they were never seen alive again.

Mallory’s words, however, are now available to read online in their entirety for the first time. Magdalene College, Cambridge, where Mallory studied as an undergraduate from 1905 to 1908, recently digitized hundreds of pages of correspondence and other documents written and received by him.

Over the past 18 months, archivists scanned the documents in preparation for the centennial of Mallory’s disappearance. The college will display a selection of Mallory’s letters and possessions in the exhibit “George Mallory: Magdalene to the Mountain,” opening June 20.

The Everest letters outline Mallory’s meticulous preparations and equipment tests, and his optimism about their prospects. But the letters also show the darker side of mountaineering: bad weather, health issues, setbacks and doubts.

Days before his disappearance, Mallory wrote that the odds were “50 to 1 against us” in the last letter to his wife, Ruth, dated May 27, 1924.

“This has been a bad time altogether,” Mallory wrote. “I look back on tremendous efforts & exhaustion & dismal looking out of a tent door and onto a world of snow & vanishing hopes.”

He went on to describe a harrowing brush with death during a recent climb, when the ground beneath his feet collapsed, leaving him suspended “half-blind & breathless,” his weight supported only by his ice axe wedged across a crevasse as he dangled over “a very unpleasant black hole.”

Other letters Mallory exchanged with Ruth were written at the time of their courtship, while he was serving in Britain’s artillery regiment during World War I. Throughout his travels, correspondence from Ruth provided him with much-needed stability during the most challenging times, said project lead Katy Green, a college archivist at Magdalene College.

“She was the ‘rock’ at home, he says himself in his letters,” Green said. The archivist recounted one note in which Mallory told Ruth: “I’m so glad that you never wobble, because I would wobble without you.”

Yet while Mallory was clearly devoted to his wife, he nonetheless repeatedly returned to the Himalayas despite her mounting fears for his safety.

“There’s something in him that drove him,” Green said. “It might have been his wartime experience, or it might have just been the sort of person that he was.”

‘Documents of his character’

In total, the collection includes around 840 letters spanning from 1914 to 1924; Ruth wrote about 440 of those to Mallory, offering an unprecedented and highly detailed view of daily life for women in the early 20th century, Green told CNN.

Together, the letters offer readers a rare glimpse of the man behind the legend, said Jochen Hemmleb, an author and alpinist who was part of the Everest expedition that found Mallory’s body in 1999.

“They are really personal. They are documents of his character. They provide unique insights into his life, and especially into the 1924 expedition — his state of mind, his accurate planning, his ambitions,” said Hemmleb, who was not involved in the scanning project. “It’s such a treasure that these are now digitized and available for everyone to read.”

Frozen in place

Three of the digitized letters — written to Mallory by his brother, his sister and a family friend — were recovered from Mallory’s body by the Mallory and Irvine Research Expedition, which ascended Everest seeking the remains of Mallory and Irvine.

On May 1, 1999, expedition member and mountaineer Conrad Anker found a frozen corpse at an altitude of around 26,700 feet (8,138 meters) and identified it as Mallory’s from a name tag that was sewn into his clothes.

Mallory’s body was interred where it lay at the family’s request, said Anker, who was not involved in the letter digitizing project.

“Having done body recoveries in other places, it’s very laborious, and it’s very dangerous at that altitude,” he told CNN. “We collected some of his personal effects that went back to the Royal Geographical Society,” including the three letters that were later scanned at Magdalene College.

Mount Everest, the highest peak in the Himalayan mountain range, is also the tallest mountain on Earth, rising 29,035 feet (8,850 meters) above sea level on the border between Nepal and Tibet — an autonomous region in China. Its Tibetan name is Chomolungma, meaning “Goddess Mother of the World,” and its Nepali name is Sagarmatha, meaning “Goddess of the Sky.”

However, these names were unknown to 19th century British surveyors who mapped the region, and in 1865 the Royal Geographical Society named the peak Mount Everest after British surveyor Sir George Everest, a former surveyor general of India.

Mallory participated in all three of Britain’s first forays onto Everest’s slopes: in 1921, 1922 and 1924. When he vanished in 1924, he was less than two weeks shy of his 38th birthday.

Many have speculated about whether Mallory and Irvine managed to reach Everest’s summit. The climbers were last seen in the early afternoon of June 8 by expedition member and geologist Noel Odell, who was following behind and glimpsed them from a distance. Odell later found some of their equipment at a campsite, but there was no trace of Mallory and Irvine.

“(Mallory) risked a lot despite the fact that he had a family back home and three small children,” Hemmleb said. “We don’t know whether it was really irresponsible to make that final attempt, because we don’t really know what happened. It could be that in the end, he simply had bad luck.”

So close, yet so far

Decades after Mallory’s death, Sherpa Tenzing Norgay and New Zealand mountaineer Sir Edmund Hillary became the first to reach Everest’s peak, summiting on May 29, 1953. In the years that followed, thousands attempted to climb Everest, with nearly 4,000 people reaching its summit. More than 330 climbers have died trying since modern records were kept, according to the Himalayan Database, which compiles records of all expeditions in the Himalayas; some of those bodies remain on the mountain, frozen where they fell and visible to climbers who pass them by.

“If you’re out in this environment, you make peace with your own mortality and the deaths of others,” Anker said. “You’re above 8,000 meters, and when there are weather changes or your own systems cease to function due to the lack of oxygen, it gets serious really quickly.”

When mountaineers are close to a mountain’s summit, they sometimes proceed even under dangerous conditions due to so-called summit fever, a compulsion to reach the peak even at the cost of their own safety. It’s unknown whether Mallory was in the grip of summit fever when he died, but he might have thought that his reputation depended on summiting.

“That was going to be the defining moment in his life,” Anker said.

By comparison, Mallory’s team member Edward Norton had attempted to summit four days earlier but turned back at roughly the same altitude where Mallory and Irvine were seen for the last time.

“I had a conversation with one of Edward Norton’s sons a couple of years ago,” Hemmleb said. “When I asked him, do you think it was mere luck that your father survived and Mallory died? He said, ‘No, I think there was one difference: My father, Edward Norton, didn’t need the mountain.’”

As a climber himself, Hemmleb took that message to heart.

“That is something I personally learned from Mallory,” he said. “You need to be very careful not to make yourself dependent on that summit success.”

A century has elapsed since Mallory’s death, but the digitizing of these letters assures that his story will keep being told, Hemmleb said.

“This will continue beyond my own lifetime, I’m certain of that,” he added. “In a sense, it’s the expedition that never ends.”

Mindy Weisberger is a science writer and media producer whose work has appeared in Live Science, Scientific American and How It Works magazine.

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Newly mapped lost branch of the Nile could help solve long-standing pyramid mystery

ination online — Mon, 09 Sep 2024 11:31:30 +0000

Egypt’s Great Pyramid and other ancient monuments at Giza exist on an isolated strip of land at the edge of the Sahara Desert.

The inhospitable location has long puzzled archaeologists, some of whom had found evidence that the Nile River once flowed near these pyramids in some capacity, facilitating the landmarks’ construction starting 4,700 years ago.

Using satellite imaging and analysis of cores of sediment, a new study published Thursday in the journal Communications Earth & Environment has mapped a 64-kilometer (40-mile) long, dried-up, branch of the Nile, long buried beneath farmland and desert.

“Even though many efforts to reconstruct the early Nile waterways have been conducted, they have largely been confined to soil sample collections from small sites, which has led to the mapping of only fragmented sections of the ancient Nile channel systems,” said lead study author Eman Ghoneim, a professor and director of the Space and Drone Remote Sensing Lab at the University of North Carolina Wilmington’s department of Earth and ocean sciences.

“This is the first study to provide the first map of the long-lost ancient branch of the Nile River.”

Ghoneim and her colleagues refer to this extinct branch of the Nile river as Ahramat, which is Arabic for pyramids.

The ancient waterway would have been about 0.5 kilometers wide (about one-third of a mile) with a depth of at least 25 meters (82 feet) — similar to the contemporary Nile, Ghoneim said.

“The large size and extended length of the Ahramat Branch and its proximity to the 31 pyramids in the study area strongly suggests a functional waterway of great importance,” Ghoneim said.

She said the river would have played a key role in ancient Egyptians’ transportation of the enormous amount of building materials and laborers needed for the pyramids’ construction.

“Also, our research shows that many of the pyramids in the study area have (a) causeway, a ceremonial raised walkway, that runs perpendicular to the course of the Ahramat Branch and terminates directly on its riverbank.”

Hidden traces of a lost waterway

Traces of the river aren’t visible in aerial photos or in imagery from optical satellites, Ghoneim said. In fact, she only spotted something unexpected while studying radar satellite data of the wider area for ancient rivers and lakes that might reveal a new source of groundwater.

“I am a geomorphologist, a paleohydrologist looking into landforms. I have this kind of trained eye,” she said.

“While working with this data, I noticed this really obvious branch or a kind of riverbank, and it didn’t make any sense because it is really far from the Nile,” she added.

Born and raised in Egypt, Ghoneim was familiar with the cluster of pyramids in this area and had always wondered why they were built there. She applied to the National Science Foundation to investigate further, and geophysical data taken at ground level with the use of ground-penetrating radar and electromagnetic tomography confirmed it was an ancient arm of the Nile. Two long cores of earth the team extracted using drilling equipment revealed sandy sediment consistent with a river channel at a depth of about 25 meters (82 feet).

It’s possible that “countless” temples might still be buried beneath the agricultural fields and desert sands along the riverbank of the Ahramat Branch, according to the study.

Why this branch of the river dried up or disappeared is still unclear. Most likely, a period of drought and desertification swept sand into the region, silting up the river, Ghoneim said.

The study demonstrated that when the pyramids were built, the geography and riverscapes of the Nile differed significantly from those of today, said Nick Marriner, a geographer at the French National Centre for Scientific Research in Paris. He was not involved in the study but has conducted research on the fluvial history of Giza.

“The study completes an important part of the past landscape puzzle,” Marriner said. “By putting together these pieces we can gain a clearer picture of what the Nile floodplain looked like at the time of the pyramid builders and how the ancient Egyptians harnessed their environments to transport building materials for their monumental construction endeavors.”

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The Ukraine war is forcing migrating eagles to change their flight paths, scientists say

ination online — Fri, 30 Aug 2024 11:31:32 +0000

Greater spotted eagles are already a species under threat. Now, scientists have found that they have been facing yet another danger: the war in Ukraine.

Eagles have been exposed to conflict events while migrating through Ukraine, forcing them to deviate from their usual flight path, according to a study published Monday in the journal Current Biology.

Listed as “vulnerable” by the International Union for Conservation of Nature, greater spotted eagles have been largely eradicated from western and central Europe, according to the study.

However, Polesia, a large wetland region that borders Poland, Belarus, Ukraine, and Russia, remains a stronghold for the species.

On March 1, 2022, a week after Russia invaded Ukraine, the first of 21 tagged greater spotted eagles crossed into Ukraine on its usual migration, according to researchers from the UK and Estonia.

“When the conflict started in February 2022, we were kind of watching things unfold on the news like everyone else, but sitting there also with the feeling that we know our birds are about to pass through that area and wondering what that might mean for them,” lead study author Charlie Russell, a conservation scientist and ornithologist who is studying for his PhD at the UK’s University of East Anglia, told CNN Tuesday.

The study authors found that the eagles diverted significantly from their usual flight path when compared to pre-conflict migrations between 2019 and 2021, with the eagles flying further and less directly to breeding grounds.

While the researchers did not have direct observational evidence to determine the stimuli the birds could respond to, they thought noise and light from military activities could have affected their behavior.

The deviations were found to be greater at areas where the route of migration coincided with more military activity, but it differed for each bird due to varying exposures and responses to conflict, according to the researchers.

Due to greater deviations, the birds had to travel further and their migrations also took longer to complete.

Females, for example, spent an average of 246 hours travelling to breeding grounds, rather than the pre-conflict time of around 193 hours, according to the study.

The eagles travelled 85 kilometers (53 miles) further on average and, in an extreme case, one bird flew an extra 250 kilometers (155 miles) further compared to previous years, Russell said.

Males were found to travel more slowly, averaging a speed of around 7.66 meters (25 feet) per second, rather than the pre-conflict average of around 9.75 meters (32 feet) per second.

The researchers observed no difference in migration performance and deviation patterns outside of Ukraine, according to the study.

Potential breeding risk

The other significant finding was that the birds were making less stopovers than in previous years.

Stopover sites are essential places for the eagles to get food, water, rest and refuel, and shelter from poor weather during their long journeys, according to researchers.

While 18 tracked individuals – 90% of the tracked eagles – made stopovers in Ukraine while migrating between 2018 and 2021, only six made stopovers in 2022.

In the years before the conflict, 11 of the eagles used common stopover sites in Ukrainian Polesia, but these sites were not used at all in 2022.

“The combination of these two things, having to fly forever and expend more energy, and the reduced ability to recover that energy, is something that we think will have had sublethal fitness costs, which might have carried over into the breeding period that year,” Russell added.

Reduced fitness and the delayed onset of breeding due to spending more time recovering from the journey could reduce breeding success, which is already relatively low in the population, as well as impact chick provisioning and the fledgling date of young birds, according to the study.

“I think it’s very important to understand the different stresses that the environment is facing as a result of conflict so that in a post-conflict setting, we can better support not just greater spotted eagles but the wider ecosystems as well to recover,” Russell said.

“We know very little about the impacts of human conflicts on wildlife, particularly when it comes to migratory species, so this study plugs an important knowledge gap,” professor Nathalie Pettorelli, an applied ecologist and senior research fellow at the Zoological Society of London, told CNN Tuesday.

Pettorelli, who was not involved in the study, added that understanding what affects the eagles’ survival is “key” to ensuring they have a future.

“More broadly, human conflicts are on the rise globally, stressing the need for more research on the impacts of conflicts on biodiversity and, where possible, for the development of effective mitigation policies,” Pettorelli said.

Ukraine accused Russia of “ecocide” after suffering an environmental catastrophe in July due to the collapse of the Kakhovka dam in the south of the country that led to more than 100 people being killed, as well as the destruction of farmland and nature reserves.

Russell said the war in Ukraine is “really raising the profile of some of the environmental issues caused by conflict. And it’s not just in Ukraine. This is something that’ll be happening to different extents at other conflict zones as well.”

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Google and Harvard unveil most detailed ever map of human brain

ination online — Fri, 30 Aug 2024 11:22:26 +0000

en years ago, Dr. Jeff Lichtman — a professor of molecular and cellular biology at Harvard University — received a small brain sample in his lab.

Although tiny, the 1 cubic millimeter of tissue was big enough to contain 57,000 cells, 230 millimeters of blood vessels and 150 million synapses.

“It was less than a grain of rice, but we began to cut it and look at it, and it was really beautiful,” he said. “But as we were accumulating the data, I realized that we just had way, way more than we could handle.”

Eventually, Lichtman and his team ended up with 1,400 terabytes of data from the sample — roughly the content of over 1 billion books. Now, after the lab team’s decade of close collaboration with scientists at Google, that data has turned into the most detailed map of a human brain sample ever created.

300 million images

The brain sample came from a patient with severe epilepsy. It’s standard procedure, Lichtman said, to remove a small portion of the brain to stop the seizures, and then look at the tissue to make sure it’s normal. “But it was anonymized, so I knew next to nothing about the patient, other than their age and gender,” he said.

To analyze the sample, Lichtman and his team first cut it into thin sections using a knife with a blade edge made of diamond. The sections were then embedded into a hard resin and sliced again, very thinly. “About 30 nanometers, or roughly 1,000th of the thickness of a human hair. They were virtually invisible, if it weren’t for the fact that we had stained them with heavy metals, which made them visible when doing electron imaging,” he said.

That’s when the researchers realized they needed help with the data, because the resulting images would take up a significant amount of storage.

Lichtman knew that Google was working on a digital map of a fruit fly’s brain, released in 2019, and had the right computer hardware for the job. He got in touch with Viren Jain, a senior staff research scientist at Google who was working on the fruit fly project.

“There were 300 million separate images (in Harvard’s data),” Jain said. “What makes it so much data is that you’re imaging at a very high resolution, the level of an individual synapse. And just in that small sample of brain tissue there were 150 million synapses.”

To make sense of the images, scientists at Google used AI-based processing and analysis, identifying what type of cells were in each picture and how they were connected. The result is an interactive 3D model of the brain tissue, and the largest dataset ever made at this resolution of a human brain structure. Google made it available online as “Neuroglancer,” and a study was published in the journal Science at the same time, with Lichtman and Jain among the coauthors.

Understanding the brain

The collaboration between the Harvard and Google teams resulted in colorized images that make the individual components more visible, but they are otherwise a truthful representation of the tissue.

“The colors are completely arbitrary,” Jain explained, “but beyond that, there’s not much artistic license here. The whole point of this is that we’re not making it up — these are the real neurons, the real wires that exist in this brain, and we’re really just making it convenient and accessible for biologists to view and study.”

The data contained some surprises. For example, rather than forming a single connection, pairs of neurons instead have more than 50. “This is kind of like if two houses on a block had 50 separate phone lines connecting them. What’s going on there? Why are they so strongly connected? We don’t know what the function or significance of this phenomenon is yet, we’re going to have to study it further,” he said.

Eventually, observing the brain at this level of detail could help researchers make sense of unresolved medical conditions, according to Lichtman.

“What does it mean to understand our brain? The best we may be able to do is describe it, and hope that from these descriptions will come a realization, for example, about how normal brains are different from brains that are disordered, in adult psychiatric diseases or developmental disorders like the autism spectrum — that kind of comparison will be very valuable,” he said. “Eventually, it will give us some insight into what’s wrong, which, in most cases, we’re still in the dark about.”

Lichtman also believes that the dataset may be filled with other amazing details that, because of its size, haven’t been discovered yet: “And that’s why we’re sharing it online, so anyone can look at it and find things,” he added.

Next up, the team behind the project aims to create a full map of the brain of a mouse, which would require between 500 and 1,000 times the amount of data of the human brain sample.

“That would mean 1 exabyte, which is 1,000 petabytes,” Lichtman said. “A lot of people are thinking hard about how we’re going to do this, and we’re in the first year of a five-year proof of principle. I think that would be a watershed moment for neuroscience, to have a complete mammalian brain’s wiring diagram; it would answer many, many questions. And of course, it would reveal many more problems, things we hadn’t expected.”

What about mapping an entire human brain? That would be another 1,000 times bigger, Lichtman explained, which means the data would amount to 1 zettabyte. In 2016, that was the size of the entire internet traffic for the year, according to Cisco. At the moment, Lichtman said, it would not only be difficult to even store that much data, but there would be no ethically acceptable way of sourcing a pristine, well-preserved human brain.

Breaking new ground

Researchers in the same field who were not involved with the work expressed their enthusiasm when approached by CNN for comment.

“This study is wonderful, and there is so much to learn from data like this,” said Michael Bienkowski, an assistant professor of physiology and neuroscience at the University of Southern California’s Keck School of Medicine.

“Much of what we think we understand about the human brain is extrapolated from animals, but research like this is critical for revealing what truly makes us human. Visualizing neurons and other brain cells is really challenging due to their sheer density and complexity, and the current dataset does not capture the longer-range connections,” Bienkowski said.

“What other brain regions are these inputs originating from, and where do the outputs go once they leave the area? But to see all these different cell types and their interactions is incredible and makes you appreciate what a masterpiece of architecture life has given us,” he added.

Andreas Tolias, a professor of ophthalmology at Stanford University in California, agreed. “This is a remarkable technical study that reconstructs the structure of the human cortex at high resolution,” he said. “I was particularly excited about the discovery of rare axons capable of forming up to 50 synapses. This finding is intriguing and raises important questions about their computational roles.”

The brain-mapping project opens the door for future investigations, according to neuroscientist Olaf Sporns.

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How one of the world’s most successful indoor pests took over the planet

ination online — Fri, 30 Aug 2024 11:07:20 +0000

The cockroach that emerged from your sink drain and scuttled under the fridge? The nocturnal critter was most likely a German cockroach, and its ancestors were pestering people more than 2,000 years ago in southern Asia, a new study found.

The research, published May 20 in the journal Proceedings of the National Academy of Sciences, showed that the insects’ journey from scavenging in ancient Asian civilizations to getting cozy beneath your kitchen floor closely aligns with major historical shifts in global commerce, colonization and war.

German cockroaches, scientifically known as Blattella germanica, are ubiquitous in cities in the United States and around the world. The hardy pests first appeared in scientific records from 250 years ago in Europe, hence the German moniker, but little is known about their origin.

To figure out how cockroaches got there and spread to other parts of the world, first study author Dr. Qian Tang and his collaborators asked scientists and pest control experts around the globe for local specimens. The research team received 281 German cockroach samples from 57 sites in 17 countries and studied their DNA to trace their evolution.

“Our main purpose was to show how a species can travel with humans and how genetics can make up the missing part of historical records,” said Tang, an evolutionary biologist who is now a postdoctoral research associate at Harvard University.

Using genomic data from the samples, Tang was surprised to learn that the modern cockroach’s lineage goes back much further than 18th century Europe. The insect evolved from the wild Asian cockroach, scientifically known as Blattella asahinai, 2,100 years ago, according to his research.

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The lunar far side is wildly different from what we see. Scientists want to know why

ination online — Fri, 30 Aug 2024 10:39:18 +0000

When the Chang’e-4 mission landed in the Von Karman crater on January 3, 2019, China became the first and only country to land on the far side of the moon — the side that always faces away from Earth.

Now, China is sending another mission to the far side, and this time, its goal is to return the first samples of the moon’s “hidden side” to Earth.

The Chang’e-6 mission, launched Friday, is set to spend 53 days exploring the South Pole-Aitken basin to study its geology and topography as well as collect samples from different spots across the crater.

The South Pole-Aitken basin is believed to be the largest and oldest crater on the moon, spanning nearly a quarter of the lunar surface with a diameter measuring roughly 1,550 miles (2,500 kilometers). The impact crater is more than 5 miles (8 kilometers) deep.

Scientists hope that returning samples to Earth will help answer enduring questions about the intriguing far side, which hasn’t been studied as deeply as the near side, as well as confirming the moon’s origin.

“The far side of the moon is very different from the near side,” said Li Chunlai, China National Space Administration deputy chief designer. “The far is basically comprised of ancient lunar crust and highlands, so there are a lot of scientific questions to be answered there.”

No real ‘dark side’

During a NASA budget hearing on April 17, congressman David Trone asked NASA administrator Bill Nelson why China was sending a mission to the “backside” of the moon.

“They are going to have a lander on the far side of the moon, which is the side that’s always in dark,” Nelson responded. “We’re not planning to go there.”

The moon’s hidden side has sometimes been referred to as the “dark side of the moon,” largely in reference to the 1973 Pink Floyd album of the same name.

But the phrase is a bit of a misnomer for a couple of reasons, according to experts.

While the far side of the moon may seem dark from our perspective, it experiences a lunar day and lunar night just like the near side, and receives plenty of illumination. A lunar day lasts just over 29 days, while the lunar night lasts for about two weeks, according to NASA.

The same side always faces Earth because the moon takes the same amount of time to complete an orbit of Earth and rotate around its axis

Additionally, the far side of the moon has been more difficult to study, which led to the “dark side” nickname and created an air of mystery.

“Humans always want to know what’s on the other side of the mountain and the part that you can’t see, so that’s a kind of psychological motivation,” said Renu Malhotra, the Louise Foucar Marshall Science Research Professor and Regents Professor of Planetary Sciences at the University of Arizona in Tucson. “Of course, we’ve sent space probes that have orbited the moon, and we have images, so in a sense, it’s less mysterious than before.”

Several spacecraft, including NASA’s Lunar Reconnaissance Orbiter that constantly circles and takes images of the lunar surface, have helped to shed light on the moon.

Yutu-2, a lunar rover that Chang’e-4 released in 2019, also explored loose deposits of pulverized rock and dust littering the floor of Von Karman crater, located within the larger South Pole-Aitken basin.

But returning samples to Earth would enable the latest and most sensitive technology to analyze lunar rocks and dust, potentially revealing how the moon came to be and why its far side is so different from the near side.

Far side mysteries

Despite years of orbital data and samples collected during six of the Apollo missions, scientists are still trying to answer key questions about the moon.

“The reason the far side is so compelling is because it is so different than the side of the moon that we see, the near side,” said Noah Petro, NASA project scientist for both the Lunar Reconnaissance Orbiter and Artemis III, a mission which aims to land humans on the moon for the first time since 1972. “For all of human history, humans have been able to look up and see the same surface, the same side of the moon.”

But in 1959 the Soviet Union sent a probe to fly past the far side of the moon and captured the first images of it for humanity.

“We saw this completely different hemisphere: not covered in large volcanic lava flows, pockmarked with craters, a thicker crust. It just tells a different story than the near side,” Petro said.

Returning samples with robotic missions, and landing humans near the transition between the two lunar regions at the south pole through the Artemis program, “will help tell this more complete story of lunar history that we are lacking in right now,” he said.

Although scientists understand why one side of the moon always faces Earth, they don’t know why that particular side permanently faces our planet. But it could have something to do with the moon being asymmetrical, Malhotra said.

“There is some asymmetry between the side that’s facing us and the other side,” she said. “What exactly caused those asymmetries? What actually are these asymmetries? We have little understanding of that. That’s a huge scientific question.”

Orbital data has also revealed that the near side has a thinner crust and more volcanic deposits, but answers to why that is has eluded researchers, said Brett Denevi, a planetary geologist at the Johns Hopkins University’s Applied Physics Lab.

“It has a different kind of geochemical composition with some weird extra heat-producing elements. There are a ton of models for why the near side is different than the far side, but we don’t have the data yet,” Denevi said. “So going to the far side, getting samples and doing different kinds of geophysical measurements is really important to figuring out this really long, long standing mystery.”

Chang’e-6 is just one mission heading to the moon’s far side as NASA has plans to send robotic missions there as well.

Denevi helped design a mission concept for a lunar rover called Endurance, which will undertake a long drive across the South Pole-Aitken basin to collect data and samples before delivering them to the Artemis landing sites near the lunar south pole. Then, astronauts can study the samples and determine which ones to return to Earth.

Cracking the lunar code

One of the most fundamental questions that scientists have tried to answer is how the moon formed. The prevailing theory is that some kind of object had an impact with Earth early in its history, and a giant chunk that went flying off our planet formed the moon.

Scientists also want to know how the moon’s original crust formed.
Volcanic flows created dark patches on the moon, while the lighter parts of the surface represent the moon’s primordial crust.

“We think at one point the moon was entirely molten, and it was this ocean of magma, and as that solidified, minerals floated to the top of this ocean, and that’s that lighter terrain that we can see today,” Denevi said. “Getting to the really big expanses of pristine terrain on the far side is just one of the goals.”

Meanwhile, the study of impact craters littering the lunar surface provides a history of how things moved around during the solar system’s early days at a critical point when life was starting to form on Earth, Denevi said.

“As impacts were happening on the moon, impacts were happening on the Earth at the same time,” Petro said. “And so whenever we look at these ancient events on the moon, we’re learning a little bit about what’s happening on the Earth as well.”

Visiting the South Pole-Aitken basin could be the start of solving a multitude of lunar mysteries, Malhotra said. While researchers believe they have an idea of when the crater formed, perhaps 4.3 billion to 4.4 billion years ago, collecting rock samples could provide a definitive age.

“Many scientists are sure that if we figured out the age of that depression,” she said, “it’s going to unlock all kinds of mysteries about the history of the moon.”

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Study proves black holes have a ‘plunging region,’ just as Einstein predicted

ination online — Fri, 30 Aug 2024 10:30:50 +0000

Albert Einstein was right: There is an area at the edge of black holes where matter can no longer stay in orbit and instead falls in, as predicted by his theory of gravity.

Using telescopes capable of detecting X-rays, a team of astronomers has for the first time observed this area — called the “plunging region” — in a black hole about 10,000 light-years from Earth. “We’ve been ignoring this region, because we didn’t have the data,” said research scientist Andrew Mummery, lead author of the study published Thursday in the journal Monthly Notices of the Royal Astronomical Society. “But now that we do, we couldn’t explain it any other way.”

It’s not the first time that black holes have helped confirm Einstein’s grand theory, which is also known as general relativity. The first photo of a black hole, captured in 2019, had previously strengthened the revolutionary physicist’s core assumption that gravity is just matter bending the space-time fabric.

Many of Einstein’s other predictions have turned out to be correct over the years, among them gravitational waves and the universal speed limit. “He’s a tough man to bet against at this point,” said Mummery, a Leverhulme-Peierls Fellow in the department of physics at the University of Oxford in the United Kingdom.

“We went out searching for this one specifically — that was always the plan. We’ve argued about whether we’d ever be able to find it for a really long time,” Mummery said. “People said it would be impossible, so confirming it’s there is really exciting.”

‘Like the edge of a waterfall’

The observed black hole is in a system called MAXI J1820 + 070, which is made up of a star smaller than the sun and the black hole itself, estimated at 7 to 8 solar masses. The astronomers used NASA’s space-based NuSTAR and NICER telescopes to collect data and understand how hot gas, called plasma, from the star gets sucked into the black hole.

NuSTAR is short for the Nuclear Spectroscopic Telescope Array, which orbits Earth, and NICER, formally known as the Neutron star Interior Composition Explorer, is located on the International Space Station.

“Around these black holes there are big discs of orbiting material (from nearby stars),” Mummery said. “Most of it is stable, which means it can happily flow. It’s like a river, whereas the plunging region is like the edge of a waterfall — all of your support is gone and you’re just crashing headfirst. Most of what you can see is the river, but there’s this tiny region at the very end, which is basically what we found,” he added, noting that while the “river” had been widely observed, this is the first evidence of the “waterfall.”

Unlike the event horizon, which is closer to the center of the black hole and doesn’t let anything escape, including light and radiation, in the “plunging region” light can still escape, but matter is doomed by the powerful gravitational pull, Mummery explained.

The study’s findings could help astronomers better understand the formation and evolution of black holes. “We can really learn about them by studying this region, because it’s right at the edge, so it gives us the most information,” Mummery said.

One thing that’s missing from the study is an actual image of the black hole, because it is too small and far away. But another team of Oxford researchers is working on something even better than a picture: the first movie of a black hole. To achieve that, the team will first need to build a new observatory, the Africa Millimetre Telescope in Namibia, which Mummery expects to be online within a decade. The telescope, which will join the international Event Horizon Telescope collaboration that captured the groundbreaking 2019 image of the black hole, will enable scientists to observe and film large black holes at the center of the Milky Way galaxy and beyond.

A link to the past

According to Christopher Reynolds, a professor of astronomy at the University of Maryland, College Park, finding actual evidence for the “plunging region” is an important step that will let scientists significantly refine models for how matter behaves around a black hole. “For example, it can be used to measure the rotation rate of the black hole,” said Reynolds, who was not involved in the study.

Dan Wilkins, a research scientist at Stanford University in California, calls it an exciting development, and points out that in 2018 there was an enormously bright outburst of light from one of the black holes within our galaxy, paired with an excess of high-energy X-rays.

“We had hypothesized at the time that this excess was from the hot material in the ‘plunging region,’ but we did not have a full theoretical prediction of what that emission would look like,” said Wilkins, who also was not involved with the new study.

This study actually performs that calculation, he added, using Einstein’s theory of gravity to predict what the X-rays emitted by material in the “plunging region” would look like around a black hole, and compares it with the data from that bright outburst in 2018.

“This will be prime discovery space over the next decade or so,” Wilkins said, “as we look towards the next generation of X-ray telescopes that will give us more detailed measurements of the innermost regions just outside the event horizons of black holes

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