From Science Alert (US) : “Artificial Intelligence Has Found an Unknown ‘Ghost’ Ancestor in The Human Genome”

From Science Alert (US)

25 OCTOBER 2021
PETER DOCKRILL

Denisova Cave in Siberia, Russia (Cheburgenator/ CC-BY-SA-4.0/Wikimedia Commons).

Nobody knows who she was, just that she was different: a teenage girl from over 50,000 years ago of such strange uniqueness she looked to be a ‘hybrid’ ancestor to modern humans that scientists had never seen before.

Only recently, researchers have uncovered evidence she wasn’t alone. In a 2019 study analysing the complex mess of humanity’s prehistory, scientists used artificial intelligence (AI) to identify an unknown human ancestor species that modern humans encountered – and shared dalliances with – on the long trek out of Africa millennia ago.

“About 80,000 years ago, the so-called Out of Africa occurred, when part of the human population, which already consisted of modern humans, abandoned the African continent and migrated to other continents, giving rise to all the current populations”, explained evolutionary biologist Jaume Bertranpetit from the Pompeu Fabra University [Universitat Pompeu Fabra](ES).

As modern humans forged this path into the landmass of Eurasia, they forged some other things too – breeding with ancient and extinct hominids from other species.

Up until recently, these occasional sexual partners were thought to include Neanderthals and Denisovans, the latter of which were unknown until 2010.

But in this study, a third ex from long ago was isolated in Eurasian DNA, thanks to deep learning algorithms sifting through a complex mass of ancient and modern human genetic code.

Using a statistical technique called Bayesian inference, the researchers found evidence of what they call a “third introgression” – a ‘ghost’ archaic population that modern humans interbred with during the African exodus.

“This population is either related to the Neanderthal-Denisova clade or diverged early from the Denisova lineage,” the researchers wrote in their paper, meaning that it’s possible this third population in humanity’s sexual history was possibly a mix themselves of Neanderthals and Denisovans.

In a sense, from the vantage point of deep learning, it’s a hypothetical corroboration of sorts of the teenage girl ‘hybrid fossil’ identified in 2018; although there’s still more work to be done, and the research projects themselves aren’t directly linked.

“Our theory coincides with the hybrid specimen discovered recently in Denisova, although as yet we cannot rule out other possibilities”, one of the team, genomicist Mayukh Mondal from the University of Tartu [Tartu Ülikool](EE), said in a press statement at the time of discovery.

That being said, the discoveries being made in this area of science are coming thick and fast.

Also in 2018, another team of researchers identified evidence of what they called a “definite third interbreeding event” alongside Denisovans and Neanderthals, and a pair of papers published in early 2019 traced the timeline of how those extinct species intersected and interbred in clearer detail than ever before.

There’s a lot more research to be done here yet. Applying this kind of AI analysis is a decidedly new technique in the field of human ancestry, and the known fossil evidence we’re dealing with is amazingly scant.

But according to the research, what the team has found explains not only a long-forgotten process of introgression – it’s a dalliance that, in its own way, informs part of who we are today.

“We thought we’d try to find these places of high divergence in the genome, see which are Neanderthal and which are Denisovan, and then see whether these explain the whole picture,” Bertranpetit told Smithsonian.

“As it happens, if you subtract the Neanderthal and Denisovan parts, there is still something in the genome that is highly divergent.”

The findings were published in Nature Communications.

See the full article here .

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From COSMOS: “The Australian story, told beneath the sea”

From COSMOS

2 July 2020
Natalie Parletta

Archaeological sites could fill vast historical gaps.

The survey area in the Dampier Archipelago, Western Australia. Credit: Flinders University.

Submerged archaeological sites discovered off Australia’s northwest coast offer a new window into the migrations, lives and cultures of Aboriginal people thousands of years ago, when the continental shelf was dry.

This was a time when around 20 million square kilometres of land was exposed, before the last glacial loosened its grip on the planet and melted ice drowned coastal areas – and large swaths of human history – under the sea.

In Australia alone, two million square kilometres were flooded, hemming back a third of the continent.

“You’re talking about a huge, expansive cultural landscape inhabited by Aboriginal people all over the country… which is just a blank, empty map,” says Jonathan Benjamin from Flinders University, lead author of a paper published in the journal PLoS ONE.

“So if you’re looking for the whole picture on Australia’s ancient past, you’ve got to look under water, there’s just no question.”

Yet the country’s appreciation for underwater archaeology is only just emerging, after taking off in Europe over the last two decades with a growing number of sites revealed in the Mediterranean, the Baltic and the North Sea.

This is a first for Australia – and the discovery was a leap of faith.

“It was a high-risk project,” says Benjamin. “There was no guarantee that we would make a discovery of this nature, and we did.”

His team, which included colleagues from Flinders, the University of Western Australia and James Cook University, set out to show that ancient Aboriginal sites could be preserved on the seabed, venturing into unexplored territory with divers, boats, aircrafts and remote underwater sensing technologies.

Aboriginal artefacts discovered off the Pilbara coast in Western Australia represent Australia’s oldest known underwater archaeology. Credit: Flinders University.

The Deep History of Sea Country project, in partnership with the Murujuga Aboriginal Corporation, revealed two submerged settings in Murujuga Sea Country off the Pilbara coast around the Dampier Archipelago.

One site, at Flying Foam Passage, was estimated to be at least 8500 years old and bore evidence of human activity associated with a freshwater spring 14 metres deep.

The other was at Cape Bruguieres, with more than 260 lithic artefacts discovered up to 2.4 metres below sea level, dated to at least 7000 years old using radiocarbon and sea-level change analysis along with predictive modelling.

The artefacts included various food processing, cutting, grinding and muller tools, such as a combined hammer stone and grindstone, which would have been used to grind seeds.

“So you start to see the kinds of activities and the ideas that people had in mind,” says Benjamin. “They weren’t just randomly bashing rocks together; they were creating a tool that was for a purpose, whether it be a scalloped edge scraper or a long knife or a core tool that could be used like an axe.”

One big surprise was the difference between the types of archaeological remains under water and those found on land, which clearly differentiates earlier and later cultures.

The sites might have belonged to the same people who created the world-renowned Murujuga rock art, a heritage listing currently up for reconsideration.

It’s hard to tie the two together with scientific evidence, says Benjamin. “But you’d have to imagine that the people who were there who left their stone tools on a dry land that is now submerged were also making rock art in the area because it goes back tens of thousands of years.”

These things matter to people today, even if they’re 40,000 years old, he adds.

“It matters in the way we protect sites, it matters in the way we create National Parks, it matters in the way we protect against destruction and development. So the marine environment, why would it be treated any differently?”

“That should make some waves, if you pardon the pun, but it should change the landscape and the way that heritage practice and development-led archaeology is done in Australia.”

The preserved remains have vast potential. The sites could offer insights into how Aboriginal people dealt with climate change during the last glacial. Present-day people might have a relationship with the sites from their ancestral heritage. And it could shift the timing of Aboriginal settlement back even further.

“Much of what we currently understand about Australia’s deep past is based on sites which are further inland,” says Flinders’ Chelsea Wiseman, a co-author.

“This study indicates the potential for Indigenous archaeology to preserve underwater, and that in some cases the artefacts may remain undisturbed for millennia.”

Benjamin says it’s an exciting step for Australia “as we integrate maritime and Indigenous archaeology and draw connections between land and sea,” which he hopes will continue “long after you and I are gone”.

“These new discoveries are a first step toward exploring the last real frontier of Australian archaeology.”

See the full article here .

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From UC Riverside: “Ancestor of all animals identified in Australian fossils”

From UC Riverside

March 23, 2020
Holly Ober

An artist’s rendering of Ikaria wariootia. (Sohail Wasif/UCR)

A wormlike creature that lived more than 555 million years ago is the earliest bilaterian.

A team led by UC Riverside geologists has discovered the first ancestor on the family tree that contains most familiar animals today, including humans.

The tiny, wormlike creature, named Ikaria wariootia, is the earliest bilaterian, or organism with a front and back, two symmetrical sides, and openings at either end connected by a gut. The paper is published today in Proceedings of the National Academy of Sciences.

The earliest multicellular organisms, such as sponges and algal mats, had variable shapes. Collectively known as the Ediacaran Biota, this group contains the oldest fossils of complex, multicellular organisms. However, most of these are not directly related to animals around today, including lily pad-shaped creatures known as Dickinsonia that lack basic features of most animals, such as a mouth or gut.

The development of bilateral symmetry was a critical step in the evolution of animal life, giving organisms the ability to move purposefully and a common, yet successful way to organize their bodies. A multitude of animals, from worms to insects to dinosaurs to humans, are organized around this same basic bilaterian body plan.

Evolutionary biologists studying the genetics of modern animals predicted the oldest ancestor of all bilaterians would have been simple and small, with rudimentary sensory organs. Preserving and identifying the fossilized remains of such an animal was thought to be difficult, if not impossible.

For 15 years, scientists agreed that fossilized burrows found in 555 million-year-old Ediacaran Period deposits in Nilpena, South Australia, were made by bilaterians. But there was no sign of the creature that made the burrows, leaving scientists with nothing but speculation.

Scott Evans, a recent doctoral graduate from UC Riverside; and Mary Droser, a professor of geology, noticed miniscule, oval impressions near some of these burrows. With funding from a NASA exobiology grant, they used a three-dimensional laser scanner that revealed the regular, consistent shape of a cylindrical body with a distinct head and tail and faintly grooved musculature. The animal ranged between 2-7 millimeters long and about 1-2.5 millimeters wide, with the largest the size and shape of a grain of rice — just the right size to have made the burrows.

“We thought these animals should have existed during this interval, but always understood they would be difficult to recognize,” Evans said. “Once we had the 3D scans, we knew that we had made an important discovery.”

The researchers, who include Ian Hughes of UC San Diego and James Gehling of the South Australia Museum, describe Ikaria wariootia, named to acknowledge the original custodians of the land. The genus name comes from Ikara, which means “meeting place in the Adnyamathanha language. It’s the Adnyamathanha name for a grouping of mountains known as Wilpena Pound. The species name comes from Warioota Creek, which runs from the Flinders Ranges to Nilpena Station.

“Burrows of Ikaria occur lower than anything else. It’s the oldest fossil we get with this type of complexity,” Droser said. “Dickinsonia and other big things were probably evolutionary dead ends. We knew that we also had lots of little things and thought these might have been the early bilaterians that we were looking for.”

In spite of its relatively simple shape, Ikaria was complex compared to other fossils from this period. It burrowed in thin layers of well-oxygenated sand on the ocean floor in search of organic matter, indicating rudimentary sensory abilities. The depth and curvature of Ikaria represent clearly distinct front and rear ends, supporting the directed movement found in the burrows.

The burrows also preserve crosswise, “V”-shaped ridges, suggesting Ikaria moved by contracting muscles across its body like a worm, known as peristaltic locomotion. Evidence of sediment displacement in the burrows and signs the organism fed on buried organic matter reveal Ikaria probably had a mouth, anus, and gut.

“This is what evolutionary biologists predicted,” Droser said. “It’s really exciting that what we have found lines up so neatly with their prediction.”

See the full article here .

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The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

From University of Michigan: “Stone-age ‘likes’: Study establishes eggshell beads exchanged over 30,000 years”

From University of Michigan

March 9, 2020
Morgan Sherburne
morganls@umich.edu

Archeologists work at rock shelters at Sehonghong and Melikane in southern Africa. Image credit: Brian Stewart.

A clump of grass grows on an outcrop of shale 33,000 years ago. An ostrich pecks at the grass, and atoms taken up from the shale and into the grass become part of the eggshell the ostrich lays.

A member of a hunter-gatherer group living in southern Africa’s Karoo Desert finds the egg. She eats it, and cracks the shell into dozens of pieces. Drilling a hole, she strings the fragments onto a piece of sinew and files them into a string of beads.

She gifts the ornaments to friends who live to the east, where rainfall is higher, to reaffirm those important relationships. They, in turn, do the same, until the beads eventually end up with distant groups living high in the eastern mountains.

Ostrich eggshell beads have been used to cement relationships in Africa for more than 30,000 years. Image credit: John Klausmeyer, Yuchao Zhao and Brian Stewart.

Thirty-three thousand years later, a University of Michigan researcher finds the beads in what is now Lesotho, and by measuring atoms in the beads, provides new evidence for where these beads were made, and just how long hunter-gatherers used them as a kind of social currency.

In a study published in the Proceedings of the National Academy of Science, U-M paleolithic archeologist Brian Stewart and colleagues establish that the practice of exchanging these ornaments over long distances spans a much longer period of time than previously thought.

“Humans are just outlandishly social animals, and that goes back to these deep forces that selected for maximizing information, information that would have been useful for living in a hunter-gatherer society 30,000 years ago and earlier,” said Stewart, assistant professor of anthropology and assistant curator of the U-M Museum of Anthropological Archaeology.

“Ostrich eggshell beads and the jewelry made from them basically acted like Stone Age versions of Facebook or Twitter ‘likes,’ simultaneously affirming connections to exchange partners while alerting others to the status of those relationships.”

Lesotho is a small country of mountain ranges and rivers. It has the highest average of elevation in the continent and would have been a formidable place for hunter-gatherers to live, Stewart says. But the fresh water coursing through the country and belts of resources, stratified by the region’s elevation, provided protection against swings in climate for those who lived there, as early as 85,000 years ago.

Anthropologists have long known that contemporary hunter-gatherers use ostrich eggshell beads to establish relationships with others. In Lesotho, archeologists began finding small ornaments made of ostrich eggshell. But ostriches don’t typically live in that environment, and the archeologists didn’t find evidence of those ornaments being made in that region—no fragments of unworked eggshell, or beads in various stages of production.

So when archeologists began discovering eggshell beads without evidence of production, they suspected the beads arrived in Lesotho through these exchange networks. Testing the beads using strontium isotope analysis would allow the archeologists to pinpoint where they were made.

Strontium-87 is the daughter isotope of the radioactive element rubidium-87. When rubidium-87 decays it produces strontium-87. Older rocks such as granite and gneiss have more strontium than younger rocks such as basalt. When animals forage from a landscape, these strontium isotopes are incorporated into their tissues.

Lesotho is roughly at the center of a bullseye-shaped geologic formation called the Karoo Supergroup. The supergroup’s mountainous center is basalt, from relatively recent volcanic eruptions that formed the highlands of Lesotho. Encircling Lesotho are bands of much older sedimentary rocks. The outermost ring of the formation ranges between 325 and 1,000 kilometers away from the Lesotho sites.

To assess where the ostrich eggshell beads were made, the research team established a baseline of strontium isotope ratios—that is, how much strontium is available in a given location—using vegetation and soil samples as well samples from modern rodent tooth enamel from museum specimens collected from across Lesotho and surrounding areas.

According to their analysis, nearly 80% of the beads the researchers found in Lesotho could not have originated from ostriches living near where the beads were found in highland Lesotho.

“These ornaments were consistently coming from very long distances,” Stewart said. “The oldest bead in our sample had the third highest strontium isotope value, so it is also one of the most exotic.”

Stewart found that some beads could not have come from closer than 325 kilometers from Lesotho, and may have been made as far as 1,000 kilometers away. His findings also establish that these beads were exchanged during a time of climactic upheaval, about 59 to 25 thousand years ago. Using these beads to establish relationships between hunter-gatherer groups ensured one group access to others’ resources when a region’s weather took a turn for the worse.

“What happened 50,000 years ago was that the climate was going through enormous swings, so it might be no coincidence that that’s exactly when you get this technology coming in,” Stewart said. “These exchange networks could be used for information on resources, the condition of landscapes, of animals, plant foods, other people and perhaps marriage partners.”

Stewart says while archeologists have long accepted that these exchange items bond people over landscapes in the ethnographic Kalahari, they now have firm evidence that these beads were exchanged over huge distances not only in the past, but for over a long period of time. This study places another piece in the puzzle of how we persisted longer than all other humans, and why we became the globe’s dominant species.

Stewart’s co-authors include U-M graduate student Yuchao Zhao, as well as Peter Mitchell the University of Oxford, Genevieve Dewar of the University of Toronto Scarborough, and U-M’s James Gleason and Joel Blum.

See the full article here .

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The University of Michigan (U-M, UM, UMich, or U of M), frequently referred to simply as Michigan, is a public research university located in Ann Arbor, Michigan, United States. Originally, founded in 1817 in Detroit as the Catholepistemiad, or University of Michigania, 20 years before the Michigan Territory officially became a state, the University of Michigan is the state’s oldest university. The university moved to Ann Arbor in 1837 onto 40 acres (16 ha) of what is now known as Central Campus. Since its establishment in Ann Arbor, the university campus has expanded to include more than 584 major buildings with a combined area of more than 34 million gross square feet (781 acres or 3.16 km²), and has two satellite campuses located in Flint and Dearborn. The University was one of the founding members of the Association of American Universities.

Considered one of the foremost research universities in the United States,[7] the university has very high research activity and its comprehensive graduate program offers doctoral degrees in the humanities, social sciences, and STEM fields (Science, Technology, Engineering and Mathematics) as well as professional degrees in business, medicine, law, pharmacy, nursing, social work and dentistry. Michigan’s body of living alumni (as of 2012) comprises more than 500,000. Besides academic life, Michigan’s athletic teams compete in Division I of the NCAA and are collectively known as the Wolverines. They are members of the Big Ten Conference.

From University of the Witwatersrand, Johannesburg, South Africa via phys.org: “An evolving understanding of extinction”

From University of the Witwatersrand, Johannesburg, South Africa

via

phys.org

January 17, 2020
Christine Steininger
Bruce Rubidge

Encyclopædia Britannica, Inc.

Few things related to science capture the imagination more than the magic of worlds past. This includes the origins of life, dinosaurs, mass extinctions, meteorite impacts, and the evolution of our species. Understanding the evolution of life is central to the way we view ourselves and others and developing this field is thus critical.

Furthermore, South Africa’s rich palaeontological, palaeo-anthropological and archaeological record provides a unique competitive advantage to local heritage-related scientists.

Images of the natural wonders of South Africa, various sources.

Capetown. No image credit

Johannesburg. Britannica

Palaeosciences is the only discipline dedicated to understanding the origin and development of past life and its interactions with changing environments. It is the responsibility of these scientists to ensure understanding of the depth of our dependence on Earth as a life support system. Additionally, paleosciences research can provide knowledge of how to manage human interactions with the planet responsibly.

As our knowledge of the Earth expands, we begin to realise far more synergy and mutualistic relationships with the biological world—built up over millions of years—in many of the fundamental processes to secure biodiversity, soils, water, minerals, energy, and other resources.

South Africa rocks

South Africa is poised to become a global leader in an area of geographic advantage.

Because of the country’s immense diversity, antiquity, and continuity of geological, palaeontological, and archaeological records, and its rich genetic heritage, South Africa is unique in the world.

The DST-NRF Center of Excellence in Paleosciences. Credit: Wits University

The country boasts some of the most significant mineral deposits on Earth and preserves, amongst others, the oldest evidence of life on Earth from over 3,500-million years; the most distant ancestors of dinosaurs from 200-million years ago; and a remarkable record of human origins and achievements over four-million years.

Erasing Earth

The study of past biodiversity has recognised that five global extinction events have occurred in the last 500-million years, where between 65 percent and 95 percent of species went extinct over a relatively short period. South Africa has a record of four of these five extinction events. Many scientists consider that the Earth has now entered a new epoch—the Anthropocene. Like other transitions between geological eras, the marker for this transition is a mass extinction event, although this one—uniquely—is human-induced. And avoidable.

The current rate of species extinction is estimated to be 10 to 1,000 times higher than the natural, background rate. This is likely to increase as habitat destruction, global change, and other human-induced stresses on the natural environment accelerate.

South Africa is the only country in the world with the necessary fossil resources to undertake a research initiative over such an extensive period. Our fossil archives provide case studies throughout Earth’s history to understand how climactic and environmental change affect biodiversity.

Decoding the mechanisms that lead to population extirpation [localised extinction] and ultimately species extinction under climate change is critical for scenario-planning, interpreting, and possibly predicting its impact on biodiversity and to inform policy to conserve South African biodiversity in future.

See the full article here .

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The University of the Witwatersrand, Johannesburg (/vətˈvɑːtəsrənt/), is a multi-campus South African public research university situated in the northern areas of central Johannesburg. It is more commonly known as Wits University or Wits (/vəts/ or /vɪts/). The university has its roots in the mining industry, as do Johannesburg and the Witwatersrand in general. Founded in 1896 as the South African School of Mines in Kimberley, it is the third oldest South African university in continuous operation.

The university has an enrolment of 40,259 students as of 2018, of which approximately 20 percent live on campus in the university’s 17 residences. 63 percent of the university’s total enrolment is for undergraduate study, with 35 percent being postgraduate and the remaining 2 percent being Occasional Students.

The 2017 Academic Ranking of World Universities (ARWU) places Wits University, with its overall score, as the highest ranked university in Africa. Wits was ranked as the top university in South Africa in the Center for World University Rankings (CWUR) in 2016. According to the CWUR rankings, Wits occupies this ranking position since 2014.

From Yale University: “In death of dinosaurs, it was all about the asteroid — not volcanoes”

From Yale University

January 16, 2020
Jim Shelton

(© stock.adobe.com)

Volcanic activity did not play a direct role in the mass extinction event that killed the dinosaurs, according to an international, Yale-led team of researchers. It was all about the asteroid.

K-T boundary (red arrow) along Interstate 25, Raton Pass, Colorado. The Cretaceous–Paleogene boundary of 66 million years ago, marking the temporal border between the Cretaceous and Paleogene periods of geological time, was identified by a thin stratum of iridium-rich clay. During the 1970s, Walter Alvarez was doing geologic research in central Italy. There he had located an outcrop on the walls of a gorge whose limestone layers included strata both above and below the Cretaceous–Paleogene boundary. Exactly at the boundary is a thin layer of clay. Walter told his father Luis that the layer marked where the dinosaurs and much else became extinct and that nobody knew why, or what the clay was about — it was a big mystery and he intended to solve it. A team led by Luis Alvarez proposed in 1980 an extraterrestrial origin for this iridium, attributing it to an asteroid or comet impact. Their theory, known as the Alvarez hypothesis, is now widely accepted to explain the extinction of the non-avian dinosaurs. A large buried impact crater structure with an estimated age of about 66 million years was later identified under what is now the Yucatán Peninsula (the Chicxulub crater)

The Chicxulub crater is an impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is located near the town of Chicxulub, after which the crater is named. It was formed by a large asteroid or comet about 11 to 81 kilometers in diameter, the Chicxulub impactor, striking the Earth, and causing the dinosaur extinction.

In a break from a number of other recent studies, Yale assistant professor of geology & geophysics Pincelli Hull and her colleagues argue in a new research paper in Science that environmental impacts from massive volcanic eruptions in India in the region known as the Deccan Traps happened well before the Cretaceous-Paleogene extinction event 66 million years ago and therefore did not contribute to the mass extinction.

Deccan Traps at Ajanta Caves. Shaikh Munir

The hardened lava flows of the Deccan Traps, in western India. Gerta Keller

Most scientists acknowledge that the mass extinction event, also known as K-Pg, occurred after an asteroid slammed into Earth. Some researchers also have focused on the role of volcanoes in K-Pg due to indications that volcanic activity happened around the same time.

“Volcanoes can drive mass extinctions because they release lots of gases, like SO2 and CO2, that can alter the climate and acidify the world,” said Hull, lead author of the new study. “But recent work has focused on the timing of lava eruption rather than gas release.”

To pinpoint the timing of volcanic gas emission, Hull and her colleagues compared global temperature change and the carbon isotopes (an isotope is an atom with a higher or lower number of neutrons than normal) from marine fossils with models of the climatic effect of CO2 release. They concluded that most of the gas release happened well before the asteroid impact — and that the asteroid was the sole driver of extinction.

“Volcanic activity in the late Cretaceous caused a gradual global warming event of about two degrees, but not mass extinction,” said former Yale researcher Michael Henehan, who compiled the temperature records for the study. “A number of species moved toward the North and South poles but moved back well before the asteroid impact.”

Added Hull, “A lot of people have speculated that volcanoes mattered to K-Pg, and we’re saying, ‘No, they didn’t.’”

Recent work on the Deccan Traps, in India, has also pointed to massive eruptions in the immediate aftermath of the K-Pg mass extinction. These results have puzzled scientists because there is no warming event to match. The new study suggests an answer to this puzzle, as well.

“The K-Pg extinction was a mass extinction and this profoundly altered the global carbon cycle,” said Yale postdoctoral associate Donald Penman, the study’s modeler. “Our results show that these changes would allow the ocean to absorb an enormous amount of CO2 on long time scales — perhaps hiding the warming effects of volcanism in the aftermath of the event.”

German researcher André Bornemann was co-lead author of the study. Yale researcher Ellen Thomas was a co-author of the study, along with additional researchers from institutions in Germany, the United Kingdom, France, Spain, Japan, Denmark, and the United States.

The International Ocean Discovery Program, the National Science Foundation, and Yale University helped fund the research.

See the full article here .

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Yale University comprises three major academic components: Yale College (the undergraduate program), the Graduate School of Arts and Sciences, and the professional schools. In addition, Yale encompasses a wide array of centers and programs, libraries, museums, and administrative support offices. Approximately 11,250 students attend Yale.

From CSIROscope: “Keeping it plutonic with underwater hot rocks”

From CSIROscope

4 November 2019
Francis Chui
Edward Clennett
Karin Orth
Matt Marrison

Titans of science! Geologists on board RV Investigator examine rock samples from the underworld.

CSIRO RV Investigator. CSIRO Australia

Roman mythology is full of both epic love stories and epic battles. Take Pluto, the god of the underworld. His chief duty was to meet the newly dead after they rowed across the River Styx. He then bound these souls in chains and escorted them to judgement.

For times of trouble, Pluto had been gifted a helmet of invisibility and would ride into battle on an ebony chariot drawn by four black horses.

But the underworld wasn’t all bad. The Romans recognised that many good things came from under the earth – such as gold, silver, and their crops. So Pluto and his domain were not considered to be all that terrible.

Jump forward a few thousand years (stick with us on this one) and we find new gods of the underworld at the centre of our story – marine geologists. Instead of a helmet of invisibility and a chariot, our marine geologists have a rock dredge and a high-horsepower research vessel.

It’s an epic story of a different kind. One in which our rockstars uncover underwater rocks.

So, let’s look at what was dredged up on RV Investigator’s recent voyage to the Coral Sea.

Studying the underwater underworld

In some locations on Earth, the underworld is much closer to the surface than others. In these places, hot molten rock rises as plumes from deep within the Earth’s mantle to create hotspots. These hotspots often create volcanic chains on the surface as tectonic plates move over them. Where this happens underwater, chains of seamounts – undersea volcanic mountains – can form across the seafloor.

Undersea volcanic activity has been critical in the evolution of the Coral Sea region. So, scientists on our RV Investigator set sail to study it in August 2019.

Scientists tested competing hypotheses for how hotspots had influenced the evolution of the Australian plate.

Associate Professor Jo Whittaker from the University of Tasmania led this team. They set about uncovering the story of the epic battles between tectonic plates as they jostled and fought like Titans on our planet’s surface.

Voyage Chief Scientist, Assoc Prof Jo Whittaker, UTas and Prof Simon Williams with their helmets of health and safety.

A sudden feeling of dredge

Our story takes place at the site of Dredge 37. This location is a gateway to our underwater underworld, being the junction between the deep Pocklington Trough and the wide Louisiade Plateau near Papua New Guinea.

The Pocklington Trough is a trench 850 kilometers long and around 5200 meters deep. It marks a meeting of worlds between the northern margin of the Coral Sea and the southern margin of the Woodlark Basin and Papuan Peninsula. There is no evidence of the plate currently being dragged into the underworld (known as subduction). It’s actually thought to be a relict trench from where the Australian plate drove beneath Papua New Guinea.

Map to the underwater underworld studied during the voyage.

Our geologist’s chariot, RV Investigator, has advanced instruments for mapping and measuring the seafloor’s depth. These instruments work by emitting sound pulses through the water and recording the echoes from that signal. It allows scientists to calculate the water’s depth and interpret the seafloor’s structure.

Target sites for dredging are first mapped and then reviewed by scientists on board. When they find a suitable site for sampling rocks, the location is given to the bridge and deck crew standby to release the rock dredge. The vessel meanwhile is carefully manoeuvred into position to begin its dredge run.

The rock dredge is a simple but trusty tool. It’s got a chain net mounted to a sturdy steel mouth, filled with large triangular teeth. The dredge is lowered thousands of metres to the target site, where is it then crashed into the seafloor to bite chunks of seafloor rock to capture for the geologists above.

Dredge 37 yielded a bounty of rocks from the underworld. This is where our story starts to heat up.

Behold! The mighty rock dredge used to sample the underworld.

I like you but not in that way – igneous rocks

Our boy Pluto gives his name to plutonic rocks. They’re igneous rocks formed from molten rock deep in the Earth’s underworld. Don’t confuse them with platonic rocks though! They’re rocks that you have strong feelings for but not in a romantic way (your ‘friend zone’ rocks).

There wasn’t a lot of love for plutonic rocks on this voyage. It was their extrusive cousins (molten rock that flowed and formed on the surface) which hold the secrets, history and formation of the Coral Sea region. Within the matrix of these extrusive rocks are minerals researchers can use to date the age of the seafloor. They do this using the Argon-Argon dating technique.

The most prized rock within a sample is basalt. A dredge containing fresh volcanic basalt is prize greater than diamonds or gold for our marine geologists!

Dredge 37 gave up some of this precious rock. The altered basalts collected indicated some fierce battles had taken place after they formed. Many of the basalts were fractured, with a variety of veins and infill, including calcite, zeolite, and quartz.

Other igneous rocks in the dredge showed the scars of similar underworld battles. Plutonic dolerite, which forms at great depths, was altered with infiltration by quartz veins. This is a possible sign of hydrothermal activity where hot fluids flow through the already formed rock.

Altered basalt, a prized haul for our geologists. Image: Science team.

This relationship is going nowhere – sedimentary rocks

In contrast to the rocks formed in underworld fires, the dredge also brought forth rocks that formed during the slow settling of sediments and other materials. This included rudstone, carbonate mudstone and volcanic breccia.

Volcanic breccia containing many different types of rock. Image: Science team.

The rudstone and carbonate mudstone were white and dark grey, indicating the presence of calcium carbonate. Rocks containing white calcium carbonate may point to a time the seafloor was above or closer to sea level, even though it may now be many kilometres below the surface today.

Breccia generally has a more violent origin. It’s made up of different rock fragments cemented together and can tell us about past volcanic eruptions. This provides context for the type of eruption that occurred. They’re either effusive with flowing lava, or explosive where lava and rock fragments were blasted up into the air and water.

Breccia samples from this location contained more than one rock type within them (termed polymictic volcanic breccias). These point to a mixing of sediments and materials from nearby volcanic eruptions.

It’s time for a change – metamorphic rocks

Dredge 37 also recovered the beautiful serpentinite. Not to be confused with Pluto’s wife, the beautiful Proserpine, who he kidnapped and took to the underworld to live with him.

Serpentinite is a metamorphic rock. It forms when certain rocks (ultramafic for those playing at home) are altered in underwater environments near the Earth’s surface. Its formation can point to a battle between worlds, as grinding tectonic plates open fractures into the underworld, allowing fluids to penetrate and alter the dry rocks beneath.

The beautiful serpentinite formed by water percolating through the dry underworld. Image: Science team.

How will this all end?

The underworld is the source of many stories that both captured the imagination and guided the ancient Romans in their daily lives. The research on this voyage into our underwater underworld of the Coral Sea is no different.

It will increase our understanding of the age and evolution of the Coral Sea’s seafloor, and the chains of seamounts formed. It will also help define the extent of Australian continental crust in the Coral Sea – where one world ends and the next begins.

Scientists from all over the world will now work on these rocks, giving them the material to tell the story of our underworld, creating a new understanding of the battles that took place to form the surface of our planet – above and below the waves – in bygone eras.

Modern-day bards of the internet will tell the tale of this voyage for years to come!

See the full article here .

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SKA/ASKAP radio telescope at the Murchison Radio-astronomy Observatory (MRO) in Mid West region of Western Australia

So what can we expect these new radio projects to discover? We have no idea, but history tells us that they are almost certain to deliver some major surprises.

Making these new discoveries may not be so simple. Gone are the days when astronomers could just notice something odd as they browse their tables and graphs.

Nowadays, astronomers are more likely to be distilling their answers from carefully-posed queries to databases containing petabytes of data. Human brains are just not up to the job of making unexpected discoveries in these circumstances, and instead we will need to develop “learning machines” to help us discover the unexpected.

With the right tools and careful insight, who knows what we might find.

CSIRO, the Commonwealth Scientific and Industrial Research Organisation, is Australia’s national science agency and one of the largest and most diverse research agencies in the world.

From COSMOS: “Before the dinosaurs” Wow!!

COSMOS

1.15.17
James Mitchell Crow

Welcome to the dawn of the Permian, 290 million years ago. Reptiles with waterproof skin and eggs are colonising the land.

They are not dinosaurs, but synapsids: a group defined by the single hole in the skull behind each eye where jaw muscles attach. Mammals are synapsids too, so these creatures are more closely related to us than to dinosaurs.

Sail-backed synapsids, like the plant-eating Edaphosaurus on the right, are common. They can grow up to 3.5 metres long. The carnivorous Dimetrodon, at back left, is a little longer, reaching up to 4.6 metres. The sails on these species may have heated and cooled the body. Skulking in the left foreground is the massive-skulled Ophiacodon. These early synapsids are known as pelicosaurs.

The first therapsids

By the mid-Permian, pelicosaurs are being displaced by therapsids. This group was becoming more mammal-like: their legs were positioned vertically under their body and they had three types of teeth – incisors, canines and molars. (A reptile’s teeth may be different sizes but they are all the same shape). Some were also thought to have fur and be warm- blooded.

Dinocephalians, a sub-group distinguished by their interlocking incisors, dominated the mid-Permian. They weighed up to two tonnes. Dinocephalians included herbivores such as this herd of Estemmenosuchus or Ulemosaurus, represented by the fossil, and the carnivorous Eotitanosuchus, emerging from the water, which could reach a length of five metres. The whole group mysteriously disappeared around 270 million years ago.

Credits: (artist impression) Julius Csotonyi / (fossil) Gondwana Studios

Gorgonopsids

Gorgonopsids, a later group of therapsids, were fearsome carnivores. The name refers to the Greek monster the Gorgon. Some of the largest examples include the three-metre-long Inostrancevia (see fossil), and the similarly sized Dinogorgons, shown here fighting over a carcass.

Gorgonopsids were characterised by their large, powerful jaws and sabre-teeth. But their mighty incisors could not save them from the biggest mass extinction event in Earth’s history. Thought to have been triggered by a series of massive volcanic eruptions in what is now Siberia, 80-90% of plant and animal species disappeared in what is known as The Great Dying. It marked the end of the Permian and the start of the Triassic.

Credits: (artist impression) Julius Csotonyi / (fossil) Gondwana Studios

Cynodont survivors

The therapsids were almost wiped out in the Great Dying, clearing the way for dinosaurs. They were diapsids – distinguishable by two holes in the skull behind each eye socket, like modern-day birds and lizards.

A handful of therapsids survived. Among them were the herds of herbivorous Lystrosaurus, shown at the water’s edge and in fossilised form. And most importantly for us, the cynodonts: the ancestors of mammals. One is shown here edging out onto the finger of rock.

Little holes in the fossilised snouts of cynodonts suggest they had whiskers, which means they probably had fur and were warm-blooded.

The cynodonts lived in the dinosaurs’ shadow for 200 million years, until a mass extinction triggered by a crashing comet favoured this ancient lineage once again.

Credits: (artist impression) Julius Csotonyi / (fossil) Ghedoghedo / Staatliches Museum für Naturkunde Stuttgart

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From NYT: “Jawbone’s Discovery Fills Barren Evolutionary Period”

The New York Times

MARCH 4, 2015
JOHN NOBLE WILFORD

The Ledi-Geraru mandible fossil. Credit William Kimble/Arizona State University

On the morning of Jan. 29, 2013, Chalachew Seyoum was climbing a remote hill in the Afar region of his native Ethiopia, his head bent, eyes focused on the loose sediment. The site, known as Ledi-Geraru, was rich in fossils. Soon enough, he spotted a telltale shape on the surface — a premolar, as it turned out. It was attached to a piece of a mandible, or lower jawbone. He collected other pieces of a left mandible, and five teeth in all.

Mr. Seyoum, a graduate student in paleoanthropology at Arizona State University, had made a discovery that vaulted evolutionary science over a barren stretch of fossil record between two million and three million years ago. This was a time when the human genus, Homo, was getting underway. The 2.8-million-year-old jawbone of a Homo habilis predates by at least 400,000 years any previously known Homo fossils.

More significant, scientists say, is that this H. habilis lived only 200,000 years after the last known evidence of its more apelike predecessors, Australopithecus afarensis, the species made famous by “Lucy,” whose skeleton was found in the 1970s at the nearby Ethiopian site of Hadar.

The fossil of Olduvai Hominid 7, includes a partial lower jaw, bones of the brain case and hand bones. Credit John Reader

William H. Kimbel, director of the Institute of Human Origins at Arizona State, said the Ledi-Geraru jaw “helps narrow the evolutionary gap between Australopithecus and early Homo,” adding that it was an excellent “transitional fossil in a critical time period in human evolution.”

The discovery was announced Wednesday in two reports for the journal Science by researchers at Arizona State, the University of Nevada, Las Vegas, and Pennsylvania State University. One paleoanthropologist not on the teams, Fred Spoor of University College London and the Max Planck Institute for Evolutionary Anthropology in Germany, endorsed the analysis.

The Ledi-Geraru mandible fossil. Credit William Kimble/Arizona State University

Dr. Spoor said in an email that he agreed with the hypothesis that the new Ledi-Geraru mandible “derives from Australopithecus afarensis, and at 2.8 million years shows morphology that is ancestral to all early Homo.”

How could Dr. Spoor not agree with the interpretation of the findings in the new report by Brian A. Villmoare of the University of Nevada, Las Vegas, and colleagues on the Arizona State team? By coincidence, Dr. Spoor was ready to predict many of the findings in the journal Nature a day before his predictions would have been proved right in the journal Science. When the relationship between the studies became clear, the two journals agreed to simultaneous publication of the articles on Wednesday.

The hills of the Lee Adoyta region in Ethiopia expose sediments that are less than 2.67 million years old, which helps to date the mandible. Credit Erin DiMaggio/Penn State University

Dr. Spoor’s predictions were drawn from a digital reconstruction of the disturbed remains of the jaws of the original 1.8-million-year-old Homo habilis specimen found 50 years ago by the legendary fossil hunters Louis and Mary Leakey at Olduvai Gorge in Tanzania.

The reconstruction, suggesting a plausible evolutionary link between A. afarensis and H. habilis, yielded a remarkably primitive picture of a deep-rooted diversity of a species that emerged much earlier than the 2.3 million years ago suggested by some specimens. The teeth and jaws appeared to be more similar to A. afarensis than to subsequent Homo erectus or Homo sapiens, modern humans that emerged about 200,000 years ago.

Dr. Spoor’s analysis also seemed to put a new face on H. habilis. He said that individual species of early Homo were more easily recognizable by jaw structure and facial features than by differences in brain size, which tend to be highly variable. Dr. Villmoare and colleagues made similar observations in their article. Both the predictions and the mandible findings called attention to smaller teeth with the emergence of H. habilis and evidence suggesting that the species probably split in different evolutionary lines, only one of which might have been ancestral to later H. erectus and H. sapiens.

In an email, Dr. Spoor explained that the split occurred sometime before 2.3 million years ago. The lineage leading to H. habilis must have kept the primitive jaw morphology. The Ledi-Geraru specimen kept the primitive, sloping chin that links it to a Lucy-like ancestor. Other lineages must account for the fact that H. erectus and H. habilis existed together for a period more than a million years ago.

In a second report for the journal Science, Erin N. DiMaggio of Penn State and other geologists examined soil, vegetation and fossils at Ledi-Geraru. They determined that when the H. habilis left its jaw there, the habitat was dominated by mammals that lived in a more open landscape — grasslands and low shrubs — than the more wooded land often favored by A. afarensis.

But after about 2.8 million years ago, increased African aridity has been cited as a possible result of widespread climate change affecting species changes and extinctions. Kaye E. Reed, co-leader of the Arizona State team, noted that the “aridity signal” had been observed at the Ethiopian fossil site. However, she said, “it’s still too soon to say this means climate change is responsible for the origin of Homo.”

For that, Dr. Reed said, “we need a larger sample of hominin fossils, and that’s why we continued to come to the Ledi-Geraru area to search.” That, and to learn more about the evolution of our genus, Homo.

See the full article here.

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