The Salt Of The Comet

More than 30 years ago, the European comet mission Giotto flew past Halley's comet. The Bernese ion mass spectrometer IMS, led by Prof. em. Hans Balsiger, was on board. A key finding from the measurements taken by this instrument was that there appeared to be a lack of nitrogen in Halley's coma - the nebulous covering of comets which forms when a comet passes close to the sun.

1/20/2020 

Gas and dust rise from "Chury's" surface as the comet approaches the
point of its orbit closest to the sun  [Credit: ESA/Rosetta/NAVCAM]

Although nitrogen (N) was discovered in the form of ammonia (NH3) and hydrocyanic acid (HCN), the incidence was far removed from the expected cosmic incidence. More than 30 years later, researchers have solved this mystery thanks to a happy accident.

This is a result of the analysis of data from the Bernese mass spectrometer ROSINA, which collected data on the comet 67P/Churyumov-Gerasimenko, called Chury for short, on board the ESA space probe Rosetta (see info box below).

Risky flight through the comet Chury's dust cloud

Less than a month before the end of the Rosetta mission, the space probe was just 1.9 km above the surface of Chury as it flew through a dust cloud from the comet. This resulted in a direct impact of dust in the ion source of the mass spectrometer ROSINA-DFMS (Rosetta Orbiter Sensor for Ion and Neutral Analysis-Double Focusing Mass Spectrometer), led by the University of Bern. Kathrin Altwegg, lead researcher on ROSINA and co-author of the new study published in the prestigious journal Nature Astronomy, says: "This dust almost destroyed our instrument and confused Rosetta's position control."

A plume of dust from Comet 67P/Churyumov–Gerasimenko, seen by
 the OSIRIS Wide Angle Camera on ESA's Rosetta spacecraft on 
3 July 2016. The shadow of the plume is cast across the basin, which
 is in the Imhotep region

[Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA]

Thanks to the flight through the dust cloud, it was possible to detect substances which normally remain in the cold environment of the comet on the dust particles and therefore cannot be measured. The amount of particles, some of which had never before been measured on a comet, was astonishing. In particular, the incidence of ammonia, the chemical compound of nitrogen and hydrogen with the formula NH3, was suddenly many times greater.

"We came up with the idea that the incidence of ammonia in the ROSINA data could potentially be traced back to the occurrence of ammonium salts," explains Altwegg. "As a salt, ammonia has a much higher evaporation temperature than ice and is therefore mostly present in the form of a solid in the cold environment of a comet. It has not been possible to measure these solids either through remote sensing with telescopes or on the spot until now."

Ammonium salt and its role in the emergence of life

Extensive laboratory work was needed in order to prove the presence of these salts in cometary ice. "The ROSINA team has found traces of five different ammonium salts: ammonium chloride, ammonium cyanide, ammonium cyanate, ammonium formate and ammonium acetate," says the chemist on the ROSINA team and co-author of the current study, Dr. Nora Hanni.

Ammonium chloride is one of five different ammonium salts the ROSINA team has found traces of [Credit: University of Bern]

"Until now, the apparent absence of nitrogen on comets was a mystery. Our study now shows that it is very probable that nitrogen is present on comets, namely in the form of ammonium salts," Hanni continues.

The ammonium salts discovered include several astrobiologically relevant molecules which may result in the development of urea, amino acids, adenine and nucleotides. Kathrin Altwegg says: "This is definitely a further indication that comet impacts may be linked with the emergence of life on Earth."

Source: University of Bern [January 20, 2020]

Remains Of Pre-Hispanic Sweat Lodge Found Near La Merced, Mexico City

Archaeologists have discovered the remains of a pre-Hispanic sweat lodge near La Merced, a market area in the historic center of Mexico City.

1/23/2020 

Credit: Edith Camacho, INAH

The National Institute of Anthropology and History (INAH) said in a statement Tuesday that the temazcal, as a domed, pre-Hispanic sweat lodge made out of mud or stone is known, was found during an excavation at a property on Talavera street, which is now known for the sale of baby Jesus statues.

Temazcales were used by indigenous people in Mesoamerica for medicinal purposes, spiritual rituals and childbirth.

Credit: Edith Camacho, INAH

Archaeologists found blocks made out of adobe and tezontle –a volcanic rock – that were used to build the sweat lodge as well as a bathtub used to heat the structure with steam. Based on the remains they found, the INAH team concluded that the temazcal was five meters long and about three meters wide.

INAH said the discovery has allowed archaeologists to pinpoint the location of Temazcaltitlan, one of the oldest neighborhoods of Tenochtitlan, the Mexica capital that would become Mexico City.

Credit: Edith Camacho, INAH

According to a chronicle of pre-Hispanic times in Tenochtitlan, a temazcal was built in Temazcaltitlan to bathe and purify Quetzalmoyahuatzin, a noble Mexica girl.

Hernando Alvarado Tezozomoc, a noble indigenous man who lived in colonial times, wrote in his Cronica Mexicayotl that ordinary residents of Tenochtitlan also bathed there.

Credit: Edith Camacho, INAH

The head of the INAH team that found the temazcal said the discovery is the first concrete evidence of Temazcaltitlan’s vocation as a center of bathing and purification.

Victor Esperon Calleja said the neighborhood belonged to the district of Teopan (also known as Zoquipan), which was the first territory built on Lake Texcoco and occupied by the Mexicas. It is believed that the female deities of earth, fertility, water and the pre-Hispanic beverage pulque were also worshipped in Temazcaltitlan.

Credit: Edith Camacho, INAH

In addition to the temazcal remains, on the same Talavera street property archaeologists found the remnants of a home that was possibly inhabited by a noble indigenous family shortly after the Spanish conquest and structures of a tannery, which operated during the last century of colonial rule before Mexico gained its independence in the early 19th century.

“The findings suggest that in the 16th century this area was more populated than we initially thought,” Esperon said.

Credit: Edith Camacho, INAH

“Given that it was an area of chinampas [floating agricultural gardens], it was thought that there were few houses but at this property we have evidence of the wooden pilings and stones that were used for the wall foundations [of a home],” he added.

Esperon said that the methods used to build the house allowed archaeologists to date it to the first century of colonial rule between 1521 and 1620.

The walls of the four-room home were decorated with red motifs and its floor was made of adobe blocks, features that the archaeologist said indicated that it was “inhabited by an indigenous family, possibly of noble origin.”

The tannery, Esperon said, likely made leather from cattle slaughtered at the San Lucas abattoir, which was located close to where the Pino Suarez Metro station now stands.

Source: Mexico News Daily [January 23, 2020]

EVEN BEFORE AUSTRALIA'S WILDFIRES

Platypus On Brink Of Extinction

Australia's devastating drought is having a critical impact on the iconic platypus, a globally unique mammal, with increasing reports of rivers drying up and platypuses becoming stranded.1/21/2020 

The platypus is one of the world's strangest animals
[Credit: Torsten Blackwood/AFP]

Platypuses were once considered widespread across the eastern Australian mainland and Tasmania, although not a lot is known about their distribution or abundance because of the species' secretive and nocturnal nature.

A new study led by UNSW Sydney's Centre for Ecosystem Science, funded through a UNSW-led Australian Research Council project and supported by the Taronga Conservation Society, has for the first time examined the risks of extinction for this intriguing animal.

Published in the international scientific journal Biological Conservation this month, the study examined the potentially devastating combination of threats to platypus populations, including water resource development, land clearing, climate change and increasingly severe periods of drought.

Lead author Dr Gilad Bino, a researcher at the UNSW Centre for Ecosystem Science, said action must be taken now to prevent the platypus from disappearing from our waterways.

"There is an urgent need for a national risk assessment for the platypus to assess its conservation status, evaluate risks and impacts, and prioritise management in order to minimise any risk of extinction," Dr Bino said.

Alarmingly, the study estimated that under current climate conditions and due to land clearing and fragmentation by dams, platypus numbers almost halved, leading to the extinction of local populations across about 40 per cent of the species' range, reflecting ongoing declines since European colonisation.

UNSW Sydney's Centre for Ecosystem Science leads new research into
the extinction risk of the platypus [Credit: Tahnael Hawke]

Under predicted climate change, the losses forecast were far greater because of increases in extreme drought frequencies and duration, such as the current dry spell.

Dr Bino added: "These dangers further expose the platypus to even worse local extinctions with no capacity to repopulate areas."

Documented declines and local extinctions of the platypus show a species facing considerable risks, while the International Union for Conservation of Nature (IUCN) recently downgraded the platypus' conservation status to "Near Threatened".

But the platypus remains unlisted in most jurisdictions in Australia - except South Australia, where it is endangered.

Director of the UNSW Centre for Ecosystem Science and study co-author Professor Richard Kingsford said it was unfortunate that platypuses lived in areas undergoing extensive human development that threatened their lives and long-term viability.

"These include dams that stop their movements, agriculture which can destroy their burrows, fishing gear and yabby traps which can drown them and invasive foxes which can kill them," Prof Kingsford said.

The UNSW-led project raises concerns about the decline
of platypus populations [Credit: UNSW Science]

Study co-author Professor Brendan Wintle at The University of Melbourne said it was important that preventative measures were taken now.

"Even for a presumed 'safe' species such as the platypus, mitigating or even stopping threats, such as new dams, is likely to be more effective than waiting for the risk of extinction to increase and possible failure," Prof Wintle said.

"We should learn from the peril facing the koala to understand what happens when we ignore the warning signs."

Dr Bino said the researchers' paper added to the increasing body of evidence which showed that the platypus, like many other native Australian species, was on the path to extinction.

"There is an urgent need to implement national conservation efforts for this unique mammal and other species by increasing monitoring, tracking trends, mitigating threats, and protecting and improving management of freshwater habitats," Dr Bino said.

The platypus research team is continuing to research the ecology and conservation of this enigmatic animal, collaborating with the Taronga Conservation Society, to ensure its future by providing information for effective policy and management.

Source: University of New South Wales [January 21, 2020]

Domesticated Wheat Has Complex Parentage

Certain types of domesticated wheat have complicated origins, with genetic contributions from wild and cultivated wheat populations on opposite sides of the Fertile Crescent. Terence Brown and colleagues at the University of Manchester report these findings in a new paper published in the open-access journal PLOS ONE.
1/22/2020 

Credit: WikiCommons

A wild form of wheat called emmer wheat was one of the first plant species that humans domesticated. Emmer is not grown widely today, but gave rise to the durum wheat used for pasta and hybridized with another grass to make bread wheat, so its domestication was an important step in the transition from hunting and gathering to agriculture.

While the archaeological record suggests that cultivation began in the southern Levant region bordering the eastern edge of the Mediterranean Sea around 9,500 years ago, genetic studies point to an origin in the northern region of the Fertile Crescent, in what is now Turkey. To clarify emmer's origins, researchers screened 189 types of wild and domesticated wheats and used the more that 1 million genetic variations that they identified to piece together the genetic relationships between different kinds of wheat.

Based on the analysis, the researchers propose that an emmer crop, which humans cultivated but had not yet domesticated, spread from the southern Levant to southeast Turkey, where it mixed with a wild emmer population and ultimately yielded the first domesticated variety. The results of this hybridization can be detected in wild emmer plants in Turkey today.

The complex evolutionary relationships between wild emmer and cultivated wheat varieties uncovered by the analysis are similar to the interbreeding that occurred between wild and cultivated populations of other grain crops, such as barley and rice.

The authors add: "We used next-generation DNA sequencing technologies to detect hundreds of thousands of variants in the genomes of wild and cultivated emmer wheat, giving us an unprecedented insight into the complexity of its domestication process. The patterns we observed do not fit well with a simplistic model of fast and localized domestication event but suggest instead a long process of cultivation of wild wheat by hunter-gatherer communities connected throughout the Fertile Crescent, prior to the emergence of a fully domesticated wheat form."

Source: Public Library of Science [January 22, 2020]

Life's Frankenstein Beginnings

When the Earth was born, it was a mess. Meteors and lightning storms likely bombarded the planet's surface where nothing except lifeless chemicals could survive. How life formed in this chemical mayhem is a mystery billions of years old. Now, a new study offers evidence that the first building blocks may have matched their environment, starting out messier than previously thought.

1/22/2020 

Szostak believes the earliest cells developed on land in ponds or pools, 

potentially in volcanically active regions. Ultraviolet light, lightning strikes,

 and volcanic eruptions all could have helped spark the chemical reactions

necessary for life formation [Credit: Don Kawahigashi/Unsplash]

Life is built with three major components: RNA and DNA--the genetic code that, like construction managers, program how to run and reproduce cells--and proteins, the workers that carry out their instructions. Most likely, the first cells had all three pieces. Over time, they grew and replicated, competing in Darwin's game to create the diversity of life today: bacteria, fungi, wolves, whales and humans.

But first, RNA, DNA or proteins had to form without their partners. One common theory, known as the "RNA World" hypothesis, proposes that because RNA, unlike DNA, can self-replicate, that molecule may have come first. While recent studies discovered how the molecule's nucleotides--the A, C, G and U that form its backbone--could have formed from chemicals available on early Earth, some scientists believe the process may not have been such a straightforward path.

"Years ago, the naive idea that pools of pure concentrated ribonucleotides might be present on the primitive Earth was mocked by Leslie Orgel as 'the Molecular Biologist's Dream,'" said Jack Szostak, a Nobel Prize Laureate, professor of chemistry and chemical biology and genetics at Harvard University, and an investigator at the Howard Hughes Medical Institute. "But how relatively modern homogeneous RNA could emerge from a heterogeneous mixture of different starting materials was unknown."

In a paper published in the Journal of the American Chemical Society, Szostak and colleagues present a new model for how RNA could have emerged. Instead of a clean path, he and his team propose a Frankenstein-like beginning, with RNA growing out of a mixture of nucleotides with similar chemical structures: arabino- deoxy- and ribonucleotides (ANA, DNA, and RNA).

In the Earth's chemical melting pot, it's unlikely that a perfect version of RNA formed automatically. It's far more likely that many versions of nucleotides merged to form patchwork molecules with bits of both modern RNA and DNA, as well as largely defunct genetic molecules, such as ANA. These chimeras, like the monstrous hybrid lion, eagle and serpent creatures of Greek mythology, may have been the first steps toward today's RNA and DNA.

"Modern biology relies on relatively homogeneous building blocks to encode genetic information," said Seohyun Kim, a postdoctoral researcher in chemistry and first author on the paper. So, if Szostak and Kim are right and Frankenstein molecules came first, why did they evolve to homogeneous RNA?

Kim put them to the test: He pitted potential primordial hybrids against modern RNA, manually copying the chimeras to imitate the process of RNA replication. Pure RNA, he found, is just better--more efficient, more precise, and faster--than its heterogeneous counterparts. In another surprising discovery, Kim found that the chimeric oligonucleotides--like ANA and DNA--could have helped RNA evolve the ability to copy itself. "Intriguingly," he said, "some of these variant ribonucleotides have been shown to be compatible with or even beneficial for the copying of RNA templates."

If the more efficient early version of RNA reproduced faster than its hybrid counterparts then, over time, it would out-populate its competitors. That's what the Szostak team theorizes happened in the primordial soup: Hybrids grew into modern RNA and DNA, which then outpaced their ancestors and, eventually, took over.

"No primordial pool of pure building blocks was needed," Szostak said. "The intrinsic chemistry of RNA copying chemistry would result, over time, in the synthesis of increasingly homogeneous bits of RNA. The reason for this, as Seohyun has so clearly shown, is that when different kinds of nucleotides compete for the copying of a template strand, it is the RNA nucleotides that always win, and it is RNA that gets synthesized, not any of the related kinds of nucleic acids."

So far, the team has tested only a fraction of the possible variant nucleotides available on early Earth. So, like those first bits of messy RNA, their work has only just begun.

Source: Harvard University [January 22, 2020]

Driven By Earth's Orbit, Climate Changes In Africa May Have Aided Human Migration

1/27/2020 


In 1961, John Kutzbach, then a recent college graduate, was stationed in France as an aviation weather forecaster for the U.S. Air Force. There, he found himself exploring the storied caves of Dordogne, including the prehistoric painted caves at Lascoux.

An aerial view of northern Africa, the Arabian Peninsula and the Mediterranean Basin.

 A new study led by University of Wisconsin–Madison’s John Kutzbach shows that

 changes in Earth’s orbit, greenhouse gases, and ice sheets influenced the planet’s

 climate over the last 140,000 years and may have provided wetter, greener corridors 

at times that permitted human migration out of Africa and into the Middle East 

[Credit: Google Earth]

Thinking about the ancient people and animals who would have gathered in these caves for warmth and shelter, he took up an interest in glaciology. "It was interesting to me, as a weather person, that people would live so close to an ice sheet," says Kutzbach, emeritus University of Wisconsin-Madison professor of atmospheric and oceanic sciences and the Nelson Institute for Environmental Studies.

Kutzbach went on to a career studying how changes in Earth's movements through space - the shape of its orbit, its tilt on its axis, its wobble - and other factors, including ice cover and greenhouse gases, affect its climate. Many years after reveling at Ice Age cave art, today he's trying to better understand how changes in Earth's climate may have influenced human migration out of Africa.

In a recent study published in the Proceedings of the National Academy of Sciences, Kutzbach and a team of researchers trace changes in climate and vegetation in Africa, Arabia and the Mediterranean going back 140,000 years to aid others studying the influences underlying human dispersal.

The study describes a dynamic climate and vegetation model that explains when regions across Africa, areas of the Middle East, and the Mediterranean were wetter and drier and how the plant composition changed in tandem, possibly providing migration corridors throughout time.

"We don't really know why people move, but if the presence of more vegetation is helpful, these are the times that would have been advantageous to them," Kutzbach says.

The model also illuminates relationships between Earth's climate and its orbit, greenhouse gas concentrations, and its ice sheets.

For instance, the model shows that around 125,000 years ago, northern Africa and the Arabian Peninsula experienced increased and more northerly-reaching summer monsoon rainfall that led to narrowing of the Saharan and Arabian deserts due to increased grassland. At the same time, in the Mediterranean and the Levant (an area that includes Syria, Lebanon, Jordan, Israel and Palestine), winter storm track rainfall also increased.

These changes were driven by Earth's position relative to the sun. The Northern Hemisphere at the time was as close as possible to the sun during the summer, and as far away as possible during the winter. This resulted in warm, wet summers and cold winters.

"It's like two hands meeting," says Kutzbach. "There were stronger summer rains in the Sahara and stronger winter rains in the Mediterranean."

Given the nature of Earth's orbital movements, collectively called Milankovitch cycles, the region should be positioned this way roughly every 21,000 years. Every 10,000 years or so, the Northern Hemisphere would then be at its furthest point from the sun during the summer, and closest during winter.

Indeed, the model showed large increases in rainfall and vegetation at 125,000, at 105,000, and at 83,000 years ago, with corresponding decreases at 115,000, at 95,000 and at 73,000 years ago, when summer monsoons decreased in magnitude and stayed further south.

Between roughly 70,000 and 15,000 years ago, Earth was in a glacial period and the model showed that the presence of ice sheets and reduced greenhouse gases increased winter Mediterranean storms but limited the southern retreat of the summer monsoon. The reduced greenhouse gases also caused cooling near the equator, leading to a drier climate there and reduced forest cover.

These changing regional patterns of climate and vegetation could have created resource gradients for humans living in Africa, driving migration outward to areas with more water and plant life.

For the study, the researchers, including Kutzbach's UW-Madison colleagues Ian Orland and Feng He, along with researchers at Peking University and the University of Arizona, used the Community Climate System Model version 3 from the National Center for Atmospheric Research. They ran simulations that accounted for orbital changes alone, combined orbital and greenhouse gas changes, and a third that combined those influences plus the influence of ice sheets.

It was Kutzbach who, in the 1970s and 1980s, confirmed that changes in Earth's orbit can drive the strength of summer monsoons around the globe by influencing how much sunlight, and therefore, how much warming reaches a given part of the planet.

Forty years ago, there was evidence for periodic strong monsoons in Africa, but no one knew why, Kutzbach says. He showed that orbital changes on Earth could lead to warmer summers and thus, stronger monsoons. He also read about periods of "greening" in the Sahara, often used to explain early human migration into the typically-arid Middle East.

"My early work prepared me to think about this," he says.

His current modeling work mostly agrees with collected data from each region, including observed evidence from old lake beds, pollen records, cave features, and marine sediments. A recent study led by Orland used cave records in the Levant to show that summer monsoons reached into the region around 125,000 years ago.

"We get some things wrong (in the model)," says Kutzbach, so the team continues to refine it. For instance, the model doesn't get cold enough in southern Europe during the glacial period and not all vegetation changes match observed data. Computing power has also improved since they ran the model.

"This is by no means the last word," Kutzbach says. "The results should be looked at again with an even higher-resolution model."

Author: Kelly April Tyrrell | Source: University of Wisconsin-Madison [January 27, 2020]

New Predatory Dinosaur Added To Australia's Prehistory

1/29/2020 


Evidence of agile, carnivorous two-legged dinosaurs known as noasaurids have been found across the now dispersed land masses that once formed the ancient southern supercontinent of Gondwana, but never in Australia—until now.



The Lightning Ridge noasaurid bone in approximate life position,
with a human for scale [Credit: Tom Brougham]
Researchers identified a single neck bone found in an opal mine near the outback town of Lightning Ridge, New South Wales, as belonging to a noasaurid, and then realised that another fossil discovered in 2012 along the south coast of Victoria was from the same group.

Noasaurid are a rare group of theropod dinosaurs—two legged carnivores—that lived in the middle to late Cretaceous Period, between about 120 and 66 million years ago. Noasaurids were small-bodied dinosaurs, many with peculiar facial features, typically less than two metres long and weighing about 20 kilograms.

The recognition of this new group of dinosaurs in Australia by palaeontologists from the Palaeoscience Research Centre at the University of New England and the Australian Opal Centre in Lightning Ridge adds a missing piece to a puzzle.

"It was assumed that noasaurids must have lived in Australia because their fossils have been found on other southern continents that, like Australia, were once part of the Gondwanan supercontinent," said lead scientist, Dr. Tom Brougham of the Palaeoscience Research Centre. "These recent fossil finds demonstrate for the first time that noasaurids once roamed across Australia. Discoveries of theropods are rare in Australia, so every little find we make reveals important details about our unique dinosaur fauna."

The researchers compared the 100 million-year-old Lightning Ridge neck bone with those from other carnivorous dinosaurs and quickly realised it was different from anything that had been found in Australia to date. "When we looked at what features this bone has compared to those of other theropods, we found that it matched closely with this strange group of dinosaurs called noasaurids," Dr. Brougham said.

This prompted us to re-examine an ankle bone of a dinosaur that was discovered in Victoria in 2012, about 20 million years older than the Lightning Ridge bone, and using the same methods we concluded that this also belonged to a noasaurid. In addition, this ankle bone is approximately the same age, or perhaps even older, than the oldest known noasaurids, which come from South America."

Noasaurids were similar in size to, and lived at the same time as, a more well-known group of carnivorous dinosaurs called dromaeosaurids or 'raptors'—infamously represented by Velociraptor in Jurassic Park—and were probably also active predators. However, while Velociraptor and kin have representatives from all over the world, noasaurids were known only from several of the southern continents (South America, Africa, Madagascar and India), which formed the supercontinent of Gondwana before it started breaking apart in the Cretaceous.

The study was published today in the journal Scientific Reports.

Source: University of New England [January 29, 2020]

Archaic Building Found At Asclepeion Sanctuary In Ancient Epidaurus

1/29/2020 

The Asclepeion of Epidaurus on the Peloponnesian Peninsula is one of the most important ancient sites in the entire world.

The Tholos of Ancient Epidaurus in the process of restoration and the 

remains of the Archaic era building that has just been discovered 

[Credit: Athens-Macedonian News Agency]

Today, it owes a great deal of its fame to the theatre, a wonder of acoustics which is still in operation today, but in ancient times it served as a medical sanctuary, and serious illnesses were healed there.

People from all over the Eastern Mediterranean region flocked to Epidaurus in antiquity to find cures for their various maladies. It was a spacious resort which included guesthouses, a gymnasium, a stadium and the famous theater, which served to “elevate the soul,” which ancient Greeks saw as the goal of all theatrical plays, both tragedies and comedies.

Along with its many luxurious facilities, the Asclepeion of Epidaurus offered beautiful, serene natural surroundings, with lush vegetation and stunning views of the surrounding mountaintops.

According to the poet Hesiod, who was active between 750 and 650 BC, Asclepius, the son of Apollo who was considered the ancient Greek god of medicine, was born in Epidaurus.

A new building found at Epidaurus’ Asclepeion area, which was dedicated to this god, gives new insight into the famous sanctuary, mainly concerning the early years of its creation.

The newly-uncovered building is a structure from the archaic era, whose function is currently unknown. It was built on a site adjacent to where the Tholos, or dome, the most iconic building of the Asclepeion, is situated.

The building, rectangular in plan, had a basement space corresponding to the ground floor, with mosaics placed in a peristyle form. According to the information gleaned so far from the excavation, which is still in progress, the building dates back to around the year 600 BC.


The theatre at Epidaurus [Credit: Geolines]

University of Athens Professor Vassilis Lamprinoudakis, head of the excavations in ancient Epidaurus, explained to the Athens-Macedonian News Agency “This means the worship of Asclepius appears to have begun earlier in the Asclepeion of Epidaurus. Until now, it was believed to have begun around 550 BC, i.e., in the middle of the sixth century BC.

“Now it is evident that the structures are earlier, and this is particularly important for the history of the sanctuary and for the history of Asclepius himself,” the archaeologist noted.

“At the place where the Tholos was later built, a part of a building, a ‘double’ building, with basement and ground floor has been found. Since there is a basement, like in the Tholos, we consider it to be a forerunner of this ‘mysterious’ building called the Tholos,” Lamprinoudakis stated.

“When it was decided to build the Tholos, this building was demolished. The empty space created by its basement was filled with relics from the old building, but also from other parts of the sanctuary. That is because (when) the great program of the 4th century BC began, some other buildings were also demolished, the material of which was buried with respect in the place,” he added.

The archaeologist explained that the name Tholos “was only given to the structure by the ancient traveler Pausanias in the second century AD. Its original name, as we know from the inscriptions of the 4th century BC, was ‘Thymeli.’ Thymeli was a kind of altar (used in sacrifice), in which offerings were made without blood.”

Lamprinoudakis continued, saying “Research tells us that the Tholos was a kind of underground house of Asclepius, where patients were treated by injection.” The patient who slept in this special place would dream of the god Asclepius to reveal to him the cure for his illness. “This former building had a function similar to that of the Tholos, that is, its basement served as the seat of Asclepius on earth,” the archaeologist explained.

“The new building, however, also gives important clues to the topography of the sanctuary. It explains the orientation of some other constructions that follow,” Lamprinoudakis concluded.

The archaeological dig at the sanctuary of Asclepius of Epidaurus, which has been carried out by the Department of History and Archeology of the University of Athens since 2016, continues today.

The excavations, carried out with the support of the Ephorate of Antiquities of Argolis, were funded by the organization “Asclipiades” in 2016-2017 and by the Stavros Niarchos Foundation in the years 2018-2019.

Author: Philip Chrysopoulos | Source: Athens-Macedonian News Agency via Greek Reporter [January 29, 2020]

New Study Debunks Myth Of Cahokia's Native American Lost Civilization

1/27/2020

A University of California, Berkeley, archaeologist has dug up ancient human feces, among other demographic clues, to challenge the narrative around the legendary demise of Cahokia, North America's most iconic pre-Columbian metropolis.

Painting of the Cahokia Mounds by William R. Iseminger [Credit: Cahokia Mounds Historic State Site]

In its heyday in the 1100s, Cahokia -- located in what is now southern Illinois -- was the center for Mississippian culture and home to tens of thousands of Native Americans who farmed, fished, traded and built giant ritual mounds.

By the 1400s, Cahokia had been abandoned due to floods, droughts, resource scarcity and other drivers of depopulation. But contrary to romanticized notions of Cahokia's lost civilization, the exodus was short-lived, according to a new UC Berkeley study.

The study takes on the "myth of the vanishing Indian" that favors decline and disappearance over Native American resilience and persistence, said lead author A.J. White, a UC Berkeley doctoral student in anthropology.

"One would think the Cahokia region was a ghost town at the time of European contact, based on the archaeological record," White said. "But we were able to piece together a Native American presence in the area that endured for centuries."

The findings, just published in the journal American Antiquity, make the case that a fresh wave of Native Americans repopulated the region in the 1500s and kept a steady presence there through the 1700s, when migrations, warfare, disease and environmental change led to a reduction in the local population.

White and fellow researchers at California State University, Long Beach, the University of Wisconsin-Madison and Northeastern University analyzed fossil pollen, the remnants of ancient feces, charcoal and other clues to reconstruct a post-Mississippian lifestyle.

Their evidence paints a picture of communities built around maize farming, bison hunting and possibly even controlled burning in the grasslands, which is consistent with the practices of a network of tribes known as the Illinois Confederation.

Unlike the Mississippians who were firmly rooted in the Cahokia metropolis, the Illinois Confederation tribe members roamed further afield, tending small farms and gardens, hunting game and breaking off into smaller groups when resources became scarce.


Credit: Herb Roe, University of California - Berkeley

The linchpin holding together the evidence of their presence in the region were "fecal stanols" derived from human waste preserved deep in the sediment under Horseshoe Lake, Cahokia's main catchment area.

Fecal stanols are microscopic organic molecules produced in our gut when we digest food, especially meat. They are excreted in our feces and can be preserved in layers of sediment for hundreds, if not thousands, of years.

Because humans produce fecal stanols in far greater quantities than animals, their levels can be used to gauge major changes in a region's population.

To collect the evidence, White and colleagues paddled out into Horseshoe Lake, which is adjacent to Cahokia Mounds State Historical Site, and dug up core samples of mud some 10 feet below the lakebed. By measuring concentrations of fecal stanols, they were able to gauge population changes from the Mississippian period through European contact.

Fecal stanol data were also gauged in White's first study of Cahokia's Mississippian Period demographic changes, published last year in the Proceedings of the National Academy of Sciences. It found that climate change in the form of back-to-back floods and droughts played a key role in the exodus of Cahokia's Mississippian inhabitants.

But while many studies have focused on the reasons for Cahokia's decline, few have looked at the region following the exodus of Mississippians, whose culture is estimated to have spread through the Midwestern, Southeastern and Eastern United States from 700 A.D. to the 1500s.

White's latest study sought to fill those gaps in the Cahokia area's history.

"There's very little archaeological evidence for an indigenous population past Cahokia, but we were able to fill in the gaps through historical, climatic and ecological data, and the linchpin was the fecal stanol evidence," White said.

Overall, the results suggest that the Mississippian decline did not mark the end of a Native American presence in the Cahokia region, but rather reveal a complex series of migrations, warfare and ecological changes in the 1500s and 1600s, before Europeans arrived on the scene, White said.

"The story of Cahokia was a lot more complex than, 'Goodbye, Native Americans. Hello, Europeans,' and our study uses innovative and unusual evidence to show that," White said.

Author: Yasmin Anwar | Source: University of California - Berkeley [January 27, 2020]

Study Reveals Pre-Hispanic History, Genetic Changes Among Indigenous Mexican Populations

1/22/2020
As more and more large-scale human genome sequencing projects get completed, scientists have been able to trace with increasing confidence both the geographical movements and underlying genetic variation of human populations. Most of these projects have favoured the study of European populations, and thus, have been lacking in representing the true ethnic diversity across the globe.

To better understand the broad demographic history of pre-Hispanic Mexico and to search for signatures of adaptive evolution, an international team led by Mexican scientists have sequenced the complete protein-coding regions of the genome, or exomes, of 78 individuals from different indigenous groups from Mexico. The genomic study is the largest of its kind for indigenous populations from the Americas [Credit: Ruben Mendoza,
National Laboratory of Genomics for Biodiversity (LANGEBIO) - UGA, CINVESTAV]

To better understand the broad demographic history of pre-Hispanic Mexico and to search for signatures of adaptive evolution, an international team led by Mexican scientists have sequenced the complete protein-coding regions of the genome, or exomes, of 78 individuals from five different indigenous groups from Northern (Rara?muri or Tarahumara, and Huichol), Central (Nahua), South (Triqui, or TRQ) and Southeast (Maya, or MYA) Mexico. The genomic study, the largest of its kind for indigenous populations from the Americas, appeared recently in the advanced online edition of Molecular Biology and Evolution.

"We modeled the demographic history of indigenous populations from Mexico with northern and southern ethnic groups (Tarahumara and Huichol) splitting 7.2 kya and subsequently diverging locally 6.5 kya (Huichol groups) and 5.7 kya (Triqui and Maya), respectively," said lead author Maria Avila-Arcos, of the National Autonomous University of Mexico. The Nahua were excluded from the final analysis due to the noise it brought to the overall analysis.

Overall, they identified 120,735 single nucleotide variants (SNV) among the individuals studied, which were used to trace back the population history. Furthermore, they were able to reconcile their data with the demographic history and fossil records of ancestral Native Americans.

"The split times we found are also coherent with previous estimates of ancestral Native Americans diverging ~17.5-14.6 KYA into Southern Native Americans or "Ancestral A," comprising Central and Southern Native Americans) and Northern Native Americans or "Ancestral B," and with an initial settlement of Mexico occurring at least 12,000 years ago, as suggested by the earliest skeletal remains dated to approximately this age found in Central Mexico and the Yucatan peninsula," said Avila-Arcos. "Studies on genome-wide data from ancient remains from Central and South America reveal genetic continuity between ancient and modern populations in some parts of the Americas over the last 8,500 years."

"This suggests that, by that time, the ancestral population of MYA was not yet genetically differentiated from others, so our estimates of northern/southern split at 7.2 KYA and Mayan/Triqui divergence at 5.7 KYA fit with this scenario."

Next, they scanned the data to identify candidate genes most important for adaptation.

"Interestingly, some of these genes had previously been identified as targets of selection in other populations," said co-corresponding author Andres Moreno Estrada, principal investigator at National Laboratory of Genomics for Biodiversity (LANGEBIO) - UGA, CINVESTAV.

These genes include SLC24A5, involved in skin pigmentation, and FAP, which was previously suggested to be under adaptive archaic introgression in Peruvians and Melanesians. Three genes were involved in the immune response. These include SYT5, implicated in innate immune response, and interleukins IL17A and IL13. The remaining candidate genes were involved in signal transduction (MPZL1), protein localization and transport (GRASP and ARFRP1), cell differentiation and spermatogenesis (GMCL), Golgi apparatus organization (UBXN2B), neuron differentiation (MANF), signaling and cardiac muscle contraction (ADRBK1), cell cycle (CDK5), microtubule organization and stabilization (NCKAP5L), and stress fiber formation (NCKIPSD).

A couple of genes stood out for the team. These included, BCL2L13, which is highly expressed in skeletal muscle and could be related to physical endurance, including high endurance long-distance running, a well-known trait of the northern Mexico Rara?muri. The KBTBD8 gene has been associated with idiopathic short stature (also found in Koreans) and the team found it to be highly differentiated in Triqui, a southern indigenous group from Oaxaca whose height is extremely low compared to other Native populations.

"We carried out the most comprehensive characterization of potentially adaptive functional variation in Indigenous peoples from the Americas to date," said Moreno Estrada. "We identified in these populations over four thousand new variants, most of them singletons, with neutral, regulatory, as well as protein-truncating and missense annotations. The average number of singletons per individual was higher in Nahua (NAH) and Maya (MYA), which is expected given these two Indigenous groups embody the descendants of the largest civilizations in Mesoamerica, and that today Nahua and Maya languages are the most spoken Indigenous languages in Mexico. Furthermore, the generated data also allowed us to propose a demographic model inferred from genomic data in Native Mexicans and to identify possible events of adaptive evolution in pre-Columbian Mexico."

Source: Oxford University Press [January 22, 2020]