Ancient Ancestors of Domestic Cat was Opportunistic

An international study by researchers from the Senckenberg Center for Human Evolution and Palaeoenvironment at the University of Tübingen has determined that the first known cats in Europe were opportunistic and did not rely directly on humans for survival.

The study reveals that around 6,200 to 4,300 years ago cats survived by hunting wild animals such as rodents and were closely associated with human agriculture.

The African wildcat (Felis silvestris lybica) is the ancestor of all present-day domestic cats. The sandy-colored animals originated on the African continent. “Around 6,000 years ago, the animals also became established in Europe, where they spread as domesticated cats,” explains Prof. Dr. Hervé Bocherens of the Senckenberg Center for Human Evolution and Palaeoenvironment at the University of Tübingen, and he continues, “The oldest fossils date back about 6,200 years and were discovered in Poland. We asked ourselves how these animals were domesticated after they spread into Europe.”


To answer these questions, Bocherens, together with the study’s lead author, Magdalena Krajcarz of the Nikolaus Kopernikus University in Toruń, Poland, and an international team, measured stable isotopes in the fossilized cats’ bone collagen.

The different isotope ratios allow scientists to make inferences about the animals’ diet. “We examined a total of six cat fossils from discovery sites in Poland. For comparison purposes, we also measured fossils of the oldest known domestic cats from Poland as well as 34 additional animals that occurred alongside the cats in Europe around 6,000 years ago,” explains the scientist from Tübingen.

The study aims to also reconstruct the historical connections between humans and cats by studying the ecology and sociology of the immigrated African wildcats.
The study’s results show that the newly arrived ancestors of the domestic cat did not entirely rely on humans. Bocherens explains, “The bones in the cat fossils contain evidence of rodents that occurred in close association with human agriculture, along with signs of wild prey animals.” These analysis results indicate that the ancestors of modern domestic cats continued to live in the wild and only obtained part of their diet near human habitations. “This means that the animals were not synanthropic, i.e., entirely adapted to humans and their environment, but – contrary to the dogs of that period – led an ‘opportunistic’ lifestyle.

When they were unable to find food in the wild, which they had to share with the native European wildcats, they were not averse to foraging in the vicinity of human dwellings,” says Bocherens in summary, and he adds, “The native European wildcats also fed on these rodents, so there really was a direct competition for food between the two forms. However, due to the ample food supply, this apparently did not lead to the displacement of either one of these felines.”

Universität Tübingen

How Governments Resist World Heritage ‘in Danger’ Listings
A study published today found national governments repeatedly resisted the placement of 41 UNESCO World Heritage sites-including the Great Barrier Reef-on the World Heritage in Danger list.

This resistance is despite the sites being just as threatened, or more threatened, than those already on the in Danger list.

The study was co-authored by a team of scientists from Australia, the UK and the US.

World Heritage sites represent both natural and cultural heritage for global humanity. Their protection sits within the jurisdiction of individual countries. An in Danger listing is intended to raise awareness of threats to these sites and encourage investment in mitigation measures, such as extra protection.

Lead author Professor Tiffany Morrison from the ARC Centre of Excellence for Coral Reef Studies at James Cook University (Coral CoE at JCU) says national governments responsible for these World Heritage sites use political strategies of rhetoric and resistance to avoid a World Heritage in Danger listing.

“Avoiding an in Danger listing happens through partial compliance and by exerting diplomatic pressure on countries that are members of the World Heritage Committee,” Prof Morrison said.

She says World Heritage in Danger listings are increasingly politicised. However, until now, little was known about what that politicisation entailed, and what to do about it.

The study found the net number of in Danger listings plateaued since the year 2000. At the same time, low visibility political strategies–such as industrial lobbying and political trade-offs associated with the listings–intensified.

“Our results also challenge the assumption that poor governance only happens in less technologically advanced economies. Rich countries often have poor governance too,” Prof Morrison said.

“We show that the influence of powerful industries in blocking environmental governance is prevalent in many regions and systems.”

The Great Barrier Reef, under the custodianship of the Australian Government, is just one of the threatened sites that continues to evade the World Heritage in Danger list.

Professor Terry Hughes, also from Coral CoE at JCU, says there is no doubt that coral reefs are in danger from man-made climate change.

“The study makes no recommendation on which World Heritage sites should be formally recognised as in Danger but points out that virtually all sites are increasingly impacted by anthropogenic climate change,” Prof Hughes said.

“The Great Barrier Reef was severely impacted by three coral bleaching events in the past five years, triggered by record-breaking temperatures,” he said.

World Heritage in Danger listings are frowned upon by high-value natural resource industries such as mining, forestry and environmental tourism. Prof Morrison says the in Danger listings restrict the social license of fossil fuel industries to operate.

“Industry coalitions therefore often lobby governments, UNESCO and World Heritage Committee member countries,” she said.

“They claim an in Danger listing diminishes their nation’s international reputation and restricts foreign investment, national productivity, and local employment. Some also challenge the World Heritage system itself and undermine reports by scientists, non-governmental organisations and the media.”

These lobbying efforts heighten a government’s sense of political threat by linking the listings to national economic performance, as well as to the individual reputations of politicians and senior bureaucrats.

“At the same time, UNESCO is acutely aware of these dynamics and concerned about threats to its own reputation,” Prof Morrison said.

“Politicians and bureaucrats often work to conceal these dynamics, resulting in poor governance and continued environmental degradation.”

Prof Morrison says revealing and analysing these dynamics is a step closer to moderating them.

The study provides new evidence for how interactions, from 1972 until 2019, between UNESCO and 102 national governments, have shaped the environmental governance and outcomes for 238 World Heritage ecosystems. It also provides examples of how concerned stakeholders can, and are, experimenting with countervailing strategies that harness these politics.

“Given the global investment in environmental governance over the past 50 years, it is essential to address the hidden threats to good governance and to safeguard all ecosystems,” the study concludes.

ARC CENTRE OF EXCELLENCE FOR CORAL REEF STUDIES

Header Image Credit : Public Domain

Amud 9 is Shown to be a Neanderthal Woman Weighing 60 kg Who Lived in the Late Pleistocene

Adrián Pablos, a scientist at the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), co-leads a paper looking at the morphology and anatomy of a partial foot recovered over 25 years ago at Amud Cave (Israel), which confirms that the individual Amud 9 was a Neandertal woman from the Late Pleistocene, with a stature of some 160-166 cm***  and weight of 60 kg.

Over the course of several excavations conducted in the twentieth century at Amud Cave, remains of at least 15 Neandertals were found. A systematic and detailed study of one of these individuals, Amud 9, has found that the fossil possesses the traits usually associated with Neanderthals in the different elements of the foot, tarsals, metatarsals and phalanges, which differ from those of modern humans, both fossil and recent.

“Most of these traits are related to the typical, exceptional robustness of the postcranial skeleton, that is, from the neck down, observed in the majority of Neandertals”, explains Pablos.


Sex, weight and height

Sex, weight and height estimates in fossil populations are normally based on the dimensions of the large leg bones. However, in the case of Amud 9, only a fragment of tibia, the talus or ankle bone, one metatarsal or instep bone, and several phalanges are conserved.

As no long leg bones have been found, the researchers applied different mathematical estimates based upon the foot bones, thus obtaining an approximation to important paleobiological parameters.

“Knowing parameters such as the body size and sex of this individual helps us learn a bit more about what the Neandertals were like”, he says.


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The participants in this paper, entitled A partial Neandertal foot from the Late Middle Paleolithic of Amud Cave, Israel, are researchers from Spain (the CENIEH), the United States (University of New Mexico and Arizona State University), and Israel (Tel Aviv University and The Hebrew University of Jerusalem).

CENIEH
Header Image Credit : Osborjn M. Pearson y Adrián Pablos

*** FIVE FOOT TWO, EYES OF BLUE
https://www.calculateme.com/height/convert-cm-to-feet-inches/160-cm 

Five Foot Two, Eyes of Blue" (Art Landry, 1925)

HAS GREAT FOOTNOTES ON THE SONG AND PERFORMERS

https://www.youtube.com/watch?v=xqYJjA4aYXM

Ancient Greek Sanctuaries & Temples Had Disabled Access Thousands of Years Age

A new study by archaeologists suggests that many temples and sanctuaries of the ancient Greeks incorporated ramps that gave mobility-impaired visitors disabled access thousands of years ago.

The study was conducted by Dr Debby Sneed, from the California State University, Long Beach who made the discovery whilst analysing the distribution of ramps in ancient Greece.
Many religious sites have incorporated ramps, but research by scholars have mostly overlooked the ramps in articles and textbooks in their studies of ancient Greek architecture and analysis of the monuments.

Dr Sneed said: “Archaeologists have known about ramps on ancient Greek temples, but have routinely ignored them in their discussions of Greek architecture. More than 2,000 years ago, ancient Greeks spent time and money building ramps to aid individuals who could not easily ascend or descend stairs, and all without targeted legislation requiring them to do so”


Dr Sneed found that these ramps were particularly common at healing sanctuaries, where large numbers of visitors suffering from various illness and mobility impairments came in search of help from the healing god Asclepius.

Image Credit : Antiquity

One of the most important healing sanctuaries, the Sanctuary of Asclepius at Epidauros had 11 stone ramps installed on nine structures within the sanctuary complex that was incorporated around 370 BC.

At a sanctuary of Asclepius in Corinth, a large number of dedications to the god represent legs and feet, suggesting that people requested healing in these limbs.

“The likeliest reason why ancient Greek architects constructed ramps was to make sites accessible to mobility-impaired visitors,” concluded Dr Sneed. This research, published in the journal Antiquity, would make these ramps the earliest known evidence of ancient societies adapting their architecture to meet the needs of disabled community members.



Antiquity

Matthew Hopkins – The Real Witch-Hunter

Matthew Hopkins was an infamous witch-hunter during the 17th century, who published “The Discovery of Witches” in 1647, and whose witch-hunting methods were applied during the notorious Salem Witch Trials in colonial Massachusetts.

From the 16th century, England was in the grips of hysteria over witchcraft, caused in part by King James VI, who was obsessed with the dark arts and wrote a dissertation entitled “Daemonologie” in 1599.

James had been influenced by his personal involvement in the North Berwick witch trials from 1590, and amassed various texts on magical studies that he published into three books to describe the topics of magic, sorcery, and witchcraft, and tried to justify the persecution and punishment of a person accused of being a witch under the rule of canonical law.


The published works assisted in the creation of the witchcraft reform, that led to the English Puritan and writer – Richard Bernard to write a manual on witch-hunting in 1629 called “A Guide to Grand-Jury Men”. Historians suggest that both the “Daemonologie” and “A Guide to Grand-Jury Men” was an influence that Matthew Hopkins would draw inspiration from and have a significant impact in the direction his life would take many years later.

Matthew Hopkins was born in Great Wenham, located in Suffolk, England, and was the fourth son of James Hopkins, a Puritan vicar of St John’s of Great Wenham. After his father’s death, Hopkins moved to Manningtree in Essex and used his inheritance to present himself as a gentleman to the local aristocracy.



Hopkins’ witch-finding career began in March 1644, when an associate, John Sterne alleged that a group of women in Manningtree were conducting acts of sorcery and were trying to kill him with witchcraft. Hopkins conducted a physical investigation of the women, looking for deformities and a blemish called the “Devil’s Mark” which would lead to 23 women (sources differ in the number) being accused of witchcraft and were tried in 1645. The trial was presided over by the justices of the peace (a judicial officer of a lower or puisne court), resulting in nineteen women being convicted and hanged, and four women dying in prison.

After their success in the trail, Hopkins and Stearne travelled throughout East Anglia and nearby counties with an entourage of female assistants, falsely claiming to hold the office of Witchfinder General and also claimed to be part of an official commission by Parliament to uncover witches residing in the populous by using a practice called “pricking”. Pricking was the process of pricking a suspected witch with a needle, pin or bodkin. The practice derived from the belief that all witches and sorcerers bore a witch’s mark that would not feel pain or bleed when pricked.

Although torture was considered unlawful under English law, Hopkins would also use techniques such as sleep deprivation to confuse a victim into confessing, cutting the arm of the accused with a blunt knife (if the victim didn’t bleed then they’d be declared a witch) and tying victims to a chair who would be submerged in water (if a victim floated, then they’d be considered a witch).

This proved to be a lucrative opportunity in terms of monetary gain, as Hopkins and his company were paid for their investigations, although Hopkins states in his book “The Discovery of Witches” that “his fees were to maintain his company with three horses”, and that he took “twenty shillings a town”. Historical records from Stowmarket shows that Hopkins actually charged the town £23, taking into account inflation would be around £3800 today.

Between the years of 1644 and 1646, Hopkins and his company are believed to be responsible for the execution of around 300 supposed witches and sent to the gallows more accused people than all the other witch-hunters in England of the previous 160 years.

By 1647, Hopkins and Stearne were questioned by justices of the assizes (the precursor to the English Crown Court) into their activities, but by the time the court resumed both Hopkins and Stearne retired from witch-hunting.

That same year, Hopkins published his book, “The Discovery of Witches” which was used as a manual for the trial and conviction of Margaret Jones in the Massachusetts Bay Colony on the east coast of America. Some of Hopkins’ methods were also employed during the Salem Witch Trials, in Salem, Massachusetts in 1692–93, resulting in hundreds of inhabitants being accused and 19 people executed.

Matthew Hopkins died at his home in Manningtree on the 12th August 1647 of pleural tuberculosis and was buried in the graveyard of the Church of St Mary at Mistley Heath. Within a year of the death of Hopkins, Stearne retired to his farm and wrote his own manual “A Confirmation and Discovery of Witchcraft” hoping to further profit from the infamous career path both men had undertaken that caused the death of hundreds of innocent souls.

Archaeologists Discover Evidence of Ancient Temple Complexes at Navan Fort

Archaeologists conducting research at the Navan Fort in County Armagh, Northern Ireland have discovered evidence for consecutive temple complexes dating from the Iron Age.

The Navan Fort (Emain Macha in old Irish), is one of Ireland’s proposed royal sites and capital of the Ulaidh, that was documented during the medieval period as one of the five capitals of the five fifths that divided Ireland.

According to Irish mythology, the fort was also the seat of Chonchobhar mac Nessa, the king of Ulster in the Ulster Cycle and was described in the epic saga Táin Bó Cúailnge about the exploits of Cú Chulainn and Conal Cernach.


The fort lies at the heart of the ‘Navan complex’, which includes the Haughey’s Fort (an earlier hilltop enclosure), the King’s Stables (an artificial ritual pool) and Loughnashade (a natural lake that has yielded votive offerings) and consists of a large bank and ditch circular hilltop enclosure which also contains a small circular mound and a ring barrow.

Image Credit : Allan Leonard

The study by academics from Queen’s University Belfast, and the University of Aberdeen, in conjunction with the German Archaeological Institute, conducted a series of geophysical surveys which has revealed a vast ceremonial temple complex with further evidence of continuous activity through to the medieval period.

Dr Gleeson from Queen’s University Belfast said: “Excavation in the 1960s uncovered one of the most spectacular series of buildings of any region of prehistoric Europe, including a series of figure-of-8 buildings of the Early Iron Age and a 40m timber-ringed structure constructed c.95 BC. Upon the latter’s construction, it was immediately filled with stones and burnt to the ground in order to create a massive mound that now dominates the site.

Dr Gleeson added: “Our discoveries add significant additional data, hinting that the buildings uncovered in the 1960s were not domestic structures lived in by kings, but a series of massive temples, some of the largest and most complex ritual arena of any region of later prehistoric and pre-Roman Northern Europe.”

Header Image Credit : Allan Leonard

Nuclear sites still dangerous in 24,000 years, say space archaeologists

Some nuclear tests were conducted also in outer space and nuclear fuel was employed as propellant for rockets.

By ROSSELLA TERCATIN
JULY 26, 2020 18:30

A mushroom cloud from the Trinity Nuclear Test.
(photo credit: Wikimedia Commons)
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In July 1945, a test conducted in the deserts of New Mexico officially propelled humanity into the nuclear era. Only weeks after the Trinity Test, two atomic bombs were dropped on the Japanese cities of Hiroshima and Nagasaki.
In the following decades, while no other nuclear device was detonated in an act of war, military tests and studies continued.

Seventy-five years later, space archaeologists are wondering how to warn humanity of the future that the sites where these experiments were carried out are still dangerous, Alice Gorman, associate professor at Flinders University in Adelaide, Australia, told The Jerusalem Post.
“Teenagers nowadays do not understand how to work a dial telephone, a device that was incredibly common only one or two generations ago,” she said. “The type of plutonium used in the Trinity Test, plutonium-239, has a half-life of 24,000 years, meaning that after this time, only half of it will have decayed into a safe, non-radioactive element. How do we communicate to people living then that the site is dangerous?”
Gorman said the issue presents two challenging elements: What materials can survive such a long time, and what form of language can be used to deliver the actual message?
“As for the first difficulty, we know that stones and pottery last a very long time,” she said. “But the second point raises a big archaeological question related to symbolic communication. If we look at rock art from 20,000 years ago, we can see that there are pictures of animals, but we do not know what those pictures mean. Therefore, it is possible that our current symbols to mark radioactive sites, the yellow [and] black sign, will be interpreted as an invitation to explore the area, rather than to keep away from it.”
The issue is especially important for archaeologists of the future because in some cases, while the danger would be very limited or not even relevant on the surface, the nuclear waste and its radiation are deeper in the ground, and conducting a dig would be especially risky. For example, such is the case of Maralinga, a remote area in southern Australia where the UK conducted several nuclear tests.
Some nuclear tests were conducted in outer space, and nuclear fuel was employed as propellant for rockets.
If the UN Outer Space Treaty of 1967 prohibited nuclear weapons in space, the issue of its weaponization remains very relevant.
“Recently, Russia tested an anti-satellite weapon, reawakening the debate,” Gorman told the Post.
She began to work in space archaeology following years of work focused on stone-tool analysis and the aboriginal use of bottle glass after European settlement.
Space archaeology deals with the same issues of regular archaeology, understanding material culture, human behavior and the interaction with the surrounding environment, Gorman said.
“However, we are looking at the post-Second World War period, when the very same rockets that had been developed as missiles started to send spacecraft into orbit,” she said. “We are interested in all of what is on earth, like rocket launch sites or tracking antennas and reception development, as well as town or residential areas where people who worked on these projects live, but also satellites, space junk and all the places on other planets where humans have sent spacecrafts.”
“We are asking the same questions other archaeologists are, but we have the limitations that we cannot visit many of the sites in person, and instead, we have to rely on records or images,” she added.
Gorman was drawn to space archaeology by the idea of exploring space junk, those many objects that cannot even be seen in the sky circling the Earth. Currently, she is working on the archaeology of the International Space Station.
The recent attempt by Israel to land a robotic unit on the moon with the Beresheet mission represents a very interesting development for space archaeologists, Gorman said.
“For many decades, the only material cultures present on the moon were the American and the Soviet one,” she said. “As new countries have started to reach the moon, this has changed, bringing more diversity to the field.”

Christian, Muslim symbols found in 7th century shipwreck in Israel

Moreover, the ship also offers important insights in terms of ship construction techniques.

By ROSSELLA TERCATIN
JULY 26, 2020 20:07


Students Maayan Cohen and Michelle Creisher examine the pottery near the bulkhead at Ma‘agan Mikhael B shipwreck.
(photo credit: A. YURMAN/LEON RECANATI INSTITUTE FOR MARITIME STUDIES OF THE UNIVERSITY OF HAIFA.)

About 1,300 years ago, a 25-meter-long ship sank just a few dozen meters from the coast of Israel. Most likely, nobody perished in the incident.
But its plentiful cargo included 103 amphorae filled with all forms of agricultural products, numerous daily objects used by the crew and many other unique features, such as several Greek and Arabic inscriptions. They were swallowed by the sea and the sand, which preserved their secrets for centuries.

First spotted by two members of nearby Kibbutz Ma’agan Michael, about 35 km. south of Haifa, the site was again covered by sand and rediscovered in 2015.
The shipwreck has been excavated by the University of Haifa’s Leon Recanati Institute for Maritime Studies since 2016. It has offered archaeologists unique insights into the life of the region at the time of the transition between Byzantine and Islamic rule, trade routes and ship construction.

Moreover, the site presents the largest maritime cargo collection of Byzantine and early Islamic pottery discovered in Israel, not devoid of mystery, since two of the six types of amphorae had never before been uncovered.
The first results of the excavations were examined in two academic papers recently published in the journals Levant and Near Eastern Archaeology.
“We have not been able to determine with certainty what caused the ship to wreck, but we think it was probably a navigational mistake,” University of Haifa archaeologist Deborah Cvikel, an author of both papers, told The Jerusalem Post. “We are talking about an unusually large vessel, which was carefully built and is beautifully conserved.”
Based on the findings, the researchers believe the ship must have made stops in Cyprus, Egypt and possibly a port along the coast of Israel before sinking, she said, adding: “It was definitely traveling around the Levant.”
The size and richness of the cargo seem to contradict the notion, currently popular among scholars, that during the transition between Byzantine and Islamic rule between the seventh and eighth centuries, commerce in the Eastern Mediterranean was limited.
Inscriptions found by the archaeologists have provided a glimpse of the fascinating complexity of the period, with both Greek and Arabic letters, as well as Christian and Muslim religious symbols, making their way to the ship – whether carved in the wood of the vessel or on the amphorae.
“We do not know whether the crew was Christian or Muslim, but we found traces of both religions,” Cvikel said.
The symbols include the name of Allah written in Arabic, as well as several crosses.
Among the products found in the pottery were olives, dates, figs, fish bones, pine nuts, grapes and raisins. Many animal bones were found on the ship, perhaps do to eating practices or because they were kept by the crew as pets.
“We have not found any human bone, but we assume that because the ship sank so close to the coast, nobody died in the wreckage,” Cvikel said.
What also makes the site unique is that among the six types of amphorae identified by the archaeologists, two typologies had never emerged anywhere else. Most of the other vessels appeared to have been made in Egypt.
Moreover, the ship also offers important insights in terms of ship construction techniques.
“Ships were built using a method called ‘shell-first’ construction, which was based on strakes, giving the hull its shape and integrity,” Cvikel told the Post. “The main characteristic of this method is the use of mortise-and-tenon joints to connect hull planks. During the fifth to sixth centuries CE, ‘skeleton-first’ construction, in which strakes were fastened to the preconstructed keel and frames, was used.
“This process of ‘transition in ship construction’ has been one of the main topics in the history of shipbuilding for about 70 years, and some issues have remained unanswered. Therefore, each shipwreck of this period holds a vast amount of information that can shed further light onto the process.”
The excavation of the site, which is carried out with the involvement of several master’s and doctoral students, is ongoing, even though this summer the coronavirus emergency has prevented the archaeologist from going back to it.
“We still need to uncover the rear part of the ship, where presumably the captain lived,” Cvikel said. “We also need to carry out more analysis on many of the findings, including the amphorae, their content, the everyday objects, such as the cookware, and the animal bones.”

An origin story for a family of oddball meteorites

by Massachusetts Institute of Technology

Credit: CC0 Public Domain

Most meteorites that have landed on Earth are fragments of planetesimals, the very earliest protoplanetary bodies in the solar system. Scientists have thought that these primordial bodies either completely melted early in their history or remained as piles of unmelted rubble.

But a family of meteorites has befuddled researchers since its discovery in the 1960s. The diverse fragments, found all over the world, seem to have broken off from the same primordial body, and yet the makeup of these meteorites indicates that their parent must have been a puzzling chimera that was both melted and unmelted.

Now researchers at MIT and elsewhere have determined that the parent body of these rare meteorites was indeed a multilayered, differentiated object that likely had a liquid metallic core. This core was substantial enough to generate a magnetic field that may have been as strong as Earth's magnetic field is today.

Their results, published in the journal Science Advances, suggest that the diversity of the earliest objects in the solar system may have been more complex than scientists had assumed.

"This is one example of a planetesimal that must have had melted and unmelted layers. It encourages searches for more evidence of composite planetary structures," says lead author Clara Maurel, a graduate student in MIT's Department of Earth, Atmospheric, and Planetary Sciences (EAPS). "Understanding the full spectrum of structures, from nonmelted to fully melted, is key to deciphering how planetesimals formed in the early solar system."

Maurel's co-authors include EAPS professor Benjamin Weiss, along with collaborators at Oxford University, Cambridge University, the University of Chicago, Lawrence Berkeley National Laboratory, and the Southwest Research Institute.

Oddball irons

The solar system formed around 4.5 billion years ago as a swirl of super-hot gas and dust. As this disk gradually cooled, bits of matter collided and merged to form progressively larger bodies, such as planetesimals.

The majority of meteorites that have fallen to Earth have compositions that suggest they came from such early planetesimals that were either of two types: melted, and unmelted. Both types of objects, scientists believe, would have formed relatively quickly, in less than a few million years, early in the solar system's evolution.


If a planetesimal formed in the first 1.5 million years of the solar system, short-lived radiogenic elements could have melted the body entirely due to the heat released by their decay. Unmelted planetesimals could have formed later, when their material had lower quantities of radiogenic elements, insufficient for melting.

There has been little evidence in the meteorite record of intermediate objects with both melted and unmelted compositions, except for a rare family of meteorites called IIE irons.

"These IIE irons are oddball meteorites," Weiss says. "They show both evidence of being from primordial objects that never melted, and also evidence for coming from a body that's completely or at least substantially melted. We haven't known where to put them, and that's what made us zero in on them."

Magnetic pockets

Scientists have previously found that both melted and unmelted IIE meteorites originated from the same ancient planetesimal, which likely had a solid crust overlying a liquid mantle, like Earth. Maurel and her colleagues wondered whether the planetesimal also may have harbored a metallic, melted core.

"Did this object melt enough that material sank to the center and formed a metallic core like that of the Earth?" Maurel says. "That was the missing piece to the story of these meteorites."

The team reasoned that if the planetesimal did host a metallic core, it could very well have generated a magnetic field, similar to the way Earth's churning liquid core produces a magnetic field. Such an ancient field could have caused minerals in the planetesimal to point in the direction of the field, like a needle in a compass. Certain minerals could have kept this alignment over billions of years.

Maurel and her colleagues wondered whether they might find such minerals in samples of IIE meteorites that had crashed to Earth. They obtained two meteorites, which they analyzed for a type of iron-nickel mineral known for its exceptional magnetism-recording properties.

The team analyzed the samples using the Lawrence Berkeley National Laboratory'sAdvanced Light Source, which produces X-rays that interact with mineral grains at the nanometer scale, in a way that can reveal the minerals' magnetic direction.

Sure enough, the electrons within a number of grains were aligned in a similar direction—evidence that the parent body generated a magnetic field, possibly up to several tens of microtesla, which is about the strength of Earth's magnetic field. After ruling out less plausible sources, the team concluded that the magnetic field was most likely produced by a liquid metallic core. To generate such a field, they estimate the core must have been at least several tens of kilometers wide.

Such complex planetesimals with mixed composition (both melted, in the form of a liquid core and mantle, and unmelted in the form of a solid crust), Maurel says, would likely have taken over several million years to form—a formation period that is longer than what scientists had assumed until recently.

But where within the parent body did the meteorites come from? If the magnetic field was generated by the parent body's core, this would mean that the fragments that ultimately fell to Earth could not have come from the core itself. That's because a liquid core only generates a magnetic field while still churning and hot. Any minerals that would have recorded the ancient field must have done so outside the core, before the core itself completely cooled.

Working with collaborators at the University of Chicago, the team ran high-velocity simulations of various formation scenarios for these meteorites. They showed that it was possible for a body with a liquid core to collide with another object, and for that impact to dislodge material from the core. That material would then migrate to pockets close to the surface where the meteorites originated.

"As the body cools, the meteorites in these pockets will imprint this magnetic field in their minerals. At some point, the magnetic field will decay, but the imprint will remain," Maurel says. "Later on, this body is going to undergo a lot of other collisions until the ultimate collisions that will place these meteorites on Earth's trajectory."

Was such a complex planetesimal an outlier in the early solar system, or one of many such differentiated objects? The answer, Weiss says, may lie in the asteroid belt, a region populated with primordial remnants.

"Most bodies in the asteroid belt appear unmelted on their surface," Weiss says. "If we're eventually able to see inside asteroids, we might test this idea. Maybe some asteroids are melted inside, and bodies like this planetesimal are actually common."
Ancient micrometeoroids carried specks of stardust, water to asteroid 4 Vesta
More information: Meteorite evidence for partial differentiation and protracted accretion of planetesimals, Science Advances (2020).
Journal information: Science Advances


Provided by Massachusetts Institute of Technology

Well-preserved mammoth skeleton found in Siberian lake

Prehistoric 

Sunday, July 26, 2020

Well-preserved mammoth skeleton found in Siberian lake

Russian scientists are working to retrieve the well-preserved skeleton of a woolly mammoth, which has some ligaments still attached to it, from a lake in northern Siberia.

Fragments of the skeleton were found by local reindeer herders in the shallows of Pechevalavato Lake on the Yamalo-Nenets region a few days ago. They found part of the animal’s skull, the lower jaw, several ribs, and a foot fragment with sinews still intact.

Woolly mammoths are thought to have died out around 10,000 years ago, although scientists think small groups of them may have lived on longer in Alaska and on Russia’s Wrangel Island off the Siberian coast.

Russian television stations on Friday showed scientists looking for fragments of the skeleton in the lakeside silt.

Scientists have retrieved more bones and also located more massive fragments protruding from the silt. They said it would take significant time and special equipment to recover the rest of the skeleton — if it had all survived in position.

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