четверг, 13 июня 2019 г.

The origins of cannabis smoking: Marijuana use in the first millennium BC

Cannabis has been cultivated as an oil-seed and fibre crop for millennia in East Asia. Little is known, however, about the early use and eventual cultivation of the plant for its psychoactive and medicinal properties. Despite being one of the most widely used psychoactive drugs in the world today, there is little archaeological or historical evidence for the use of marijuana in the ancient world.

The origins of cannabis smoking: Marijuana use in the first millennium BC
The brazier and the skeleton found in the tomb M12
[Credit: Xinhua Wu]

The current study, published in the journal Science Advances, identified psychoactive compounds preserved in 2,500-year-old funerary incense burners from the Jirzankal Cemetery in the eastern Pamirs. Researchers from the Max Planck Institute for the Science of Human History, the Chinese Academy of Sciences, and the Chinese Academy of Social Sciences have shown that people were selecting plants with higher levels of THC, and burning them as part of mortuary rituals. This is the earliest clear evidence to date of cannabis being used for its psychoactive properties.
Cannabis is one of the most infamous plants on the planet today, especially in light of rapidly changing legislation surrounding its legalisation in Europe and America. Despite the popularity of the plant for its psychoactive properties, very little is known about the earliest use or cultivation of cannabis for its mind-altering effects.

The origins of cannabis smoking: Marijuana use in the first millennium BC
The excavation of the tomb M12, in which the brazier was found. In the photo, the brazier can be seen
at the middle bottom edge of the central circle [Credit: Xinhua Wu]

Cannabis plants were cultivated in East Asia for their oily seeds and fibre from at least 4000 BC. However, the early cultivated varieties of cannabis, as well as most wild populations, have low levels of THC and other cannabinoid compounds with psychoactive properties. Therefore, it has been a long-standing mystery as to when and where specific varieties of the plant with higher levels of these compounds were first recognized and used by humans.

Many historians place the origins of cannabis smoking on the ancient Central Asian steppes, but these arguments rely solely on a passage from a single ancient text from the late first millennium BC, written by the Greek historian Herodotus. Archaeologists have thus long sought to identify concrete evidence for cannabis smoking in Eurasia, but to date, there are few reliable, well-identified and properly dated examples of early cannabis use.

The origins of cannabis smoking: Marijuana use in the first millennium BC
A map and photo of the site at the Jirzankal cemetery (top row) where ancient wooden braziers containing
vestiges of cannabis were found (bottom row) [Credit: Institute of Archaeology,
Chinese Academy of Social Sciences]

The researchers in the current study uncovered the early cannabis use when they sought to identify the function of ancient wooden burners discovered by archaeologists from the Chinese Academy of Social Sciences, who were excavating in the high mountainous regions of eastern China. The burners were recovered from 2500-year-old tombs in the Pamir mountain range.
The international research team used a method called gas chromatography-mass spectrometry to isolate and identify compounds preserved in the burners. To their surprise, the chemical signature of the isolated compounds was an exact match to the chemical signature of cannabis. Moreover, the signature indicated a higher level of THC than is normally found in wild cannabis plants.

The origins of cannabis smoking: Marijuana use in the first millennium BC
The typical brazier and burnt stones in ancient Pamirs
[Credit: Xinhua Wu]

The data produced by the research effort, which brought together archaeologists and laboratory scientists from Jena, Germany and Beijing, China, provides clear evidence that ancient people in the Pamir Mountains were burning specific varieties of cannabis that had higher THC levels. The findings corroborate other early evidence for cannabis from burials further north, in the Xinjiang region of China and in the Altai Mountains of Russia.
As Nicole Boivin, Director at the Max Planck Institute for the Science of Human History notes, «The findings support the idea that cannabis plants were first used for their psychoactive compounds in the mountainous regions of eastern Central Asia, thereafter spreading to other regions of the world.»

Cannabis likely spread across exchange routes along the early Silk Road

The THC-containing residues were extracted from burners from a cemetery known as Jirzankal in the remote Pamir Mountains. Some of the skeletons recovered from the site, situated in modern-day western China, have features that resemble those of contemporaneous peoples further west in Central Asia. Objects found in the burials also appear to link this population to peoples further west in the mountain foothills of Inner Asia. Additionally, stable isotope studies on the human bones from the cemetery show that not all of the people buried there grew up locally.

The origins of cannabis smoking: Marijuana use in the first millennium BC
A larger map of the Jirzankal cemetery in China (left) and details of the landscape
where researchers found the braziers [Credit: Institute of Archaeology,
Chinese Academy of Social Sciences]

These data fit with the notion that the high-elevation mountain passes of Central and Eastern Asia played a key role in early trans-Eurasian exchange. Indeed, the Pamir region, today so remote, may once have sat astride a key ancient trade route of the early Silk Road. The Silk Road was at certain times in the past the single most important vector for cultural spread in the ancient world.

Robert Spengler, the lead archaeobotanist for the study, also at the Max Planck Institute for the Science of Human History, explains, «The exchange routes of the early Silk Road functioned more like the spokes of a wagon wheel than a long-distance road, placing Central Asia at the heart of the ancient world. Our study implies that knowledge of cannabis smoking and specific high-chemical-producing varieties of the cannabis plant were among the cultural traditions that spread along these exchange routes.»

People sought and later cultivated more psychoactive varieties of cannabis for use in burial rituals

Compared to cultivated varieties, wild cannabis plants contain lower levels of THC, one of the psychoactive compounds in cannabis. It is still unclear whether the people buried at Jirzankal actively cultivated cannabis or simply sought out higher THC-producing plants. One theory is that cannabis plants will produce greater quantities of active compounds in response to increased UV radiation and other stressors related to growing at higher elevations. So people roaming the high mountainous regions may have discovered more potent wild plants there, and initiated a new kind of use of the plant.

While modern cannabis is used primarily as a recreational drug or for medical applications, cannabis may have been used rather differently in the past. The evidence from Jirzankal suggests that people were burning cannabis at rituals commemorating the dead. They buried their kin in tombs over which they created circular mounds, stone rings and striped patterns using black and white stones.

The origins of cannabis smoking: Marijuana use in the first millennium BC
Dense patches of wild cannabis grow across the mountain foothills of Eurasia from the Caucuses to East Asia;
these plants were photographed growing in the Tian Shan Mountains of Kazakhstan
[Credit: Robert Spengler]

Whether cannabis also had other uses in society is unclear, though it seems likely that the plant’s ability to treat a variety of illnesses and symptoms was recognized early on. Yimin Yang, researcher at the University of the Chinese Academy of Sciences in Beijing observes, «This study of ancient cannabis use helps us understand early human cultural practices, and speaks to the intuitive human awareness of natural phytochemicals in plants.» Dr. Yang has studied ancient organic residues in East Asia for over ten years. He notes that «biomarker analyses open a unique window onto details of ancient plant exploitation and cultural communication that other archaeological methods cannot offer.»

Professor Boivin points out that «given the modern political climate surrounding the use of cannabis, archaeological studies like this can help us to understand the origins of contemporary cultural practice and belief structures — which, in turn, can inform policy.» As Dr. Spengler observes, «Modern perspectives on cannabis vary tremendously cross-culturally, but it is clear that the plant has a long history of human use, medicinally, ritually, and recreationally, over countless millennia.»

Source: Max Planck Institute for the Science of Human History [June 12, 2019]



Rising sea levels destroyed evidence of shell middens at many prehistoric coastal sites

Archaeological remains of coastal occupation in the form of shell middens are commonly found on today’s shorelines, and evidence for shellfish as a food source goes back 164,000 years. Within this time frame, sea-levels changed dramatically and shorelines moved on the scale of kilometers.

Rising sea levels destroyed evidence of shell middens at many prehistoric coastal sites
Farasan shell middens along palaeo shoreline
[Credit: Niklas Hausmann]

The current study, published in PLOS ONE, reveals that this movement of coastlines impacted the majority of shell middens by causing shells to wash away or to currently be underwater, and thus has skewed our understanding of past coastal subsistence around the world.

Shells as food waste are a common find in archaeological coastal sites of the last 164,000 years — but many may now be hidden from view

In this study, an international team of researchers quantified patterns that were first described by renowned Australian archaeologist and anthropologist Betty Meehan in the 1970s. Meehan described how modern-day coastal foragers of the Australian coast processed most of their shellfish on the direct shoreline to decrease transport weight and only carried some shells that still contained meat further inland to their main habitation site to be processed there.

The researchers theorized that if prehistoric people at a particular site used the same strategy, and if sea-levels rose dramatically since that time, archaeologists today would no longer find evidence of large shell middens related to that population. If only a few shells were found close to the habitation site, researchers might assume that the population did not rely heavily on shellfish for subsistence — and this would of course be incorrect.

Using a large cluster of over 3,000 prehistoric shell midden sites on the Farasan Islands in the Arabian Red Sea, the researchers assessed their spatial and temporal patterns in the context of long-term sea-level change. A selection of sites was radiocarbon dated to 7,500 to 4,700 years ago. During this period, the sea-level of the southern Red Sea was still rising as a result of melting glaciers at the end of the last Ice Age. The rise came to a stop around 6,000 years ago and the sea level was slightly higher (2-3 m) than today. This was followed by a gradual drop over ~2,000 years to our current sea levels, excepting the rise of recent decades.

Coastal exploitation of shellfish changed little during this period, and rates of shell accumulation based on radiocarbon dates indicate that 10 times more shells were deposited at the direct shoreline than at ‘post-shore’ locations, mirroring Meehan’s ethnological research. However, despite their larger size, no shore-line sites are preserved that date to before 6,000 years ago, closely following the sea-level change in this region and pointing toward a large number of sites that must have been lost to the sea since the beginning of coastal subsistence.

Usually well preserved at archaeological sites, shells are easily washed away by rising sea levels

«We already knew that coastal sites are in a precarious situation and we often rely on sites along steep cliffs or a few hundred meters inland to study the collection of shellfish dating to before today’s sea-levels,» explains first author Niklas Hausmann of the Max Planck Institute for the Science of Human History. «Now we know that not only a little bit was left at the beach, but the bulk of the shell material, which really undermines our idea of how much shellfish was eaten at sites even slightly inland.»

«With our study, we have shown that a lot more shellfish meat was eaten in times of lower sea-levels than we previously thought, and we have to get away from the simplified ‘shell equals shellfish meat’ attitude,» explains Hausmann.

Shellfish are often over-represented in the assessment of past coastal subsistence due to their hard shells preserving better than plants or even bones. However, the meat they contain is archaeologically invisible and could have been eaten anywhere. This study shows that the potential use of beach-side processing sites connected to habitational areas cannot be discounted, especially when such coastal processing sites may now be under water.

Source: Max Planck Institute for the Science of Human History [June 12, 2019]



Diet at the docks: Living and dying at the port of ancient Rome

Portus Romae was established in the middle of the first century AD and for well over 400 years was Rome’s gateway to the Mediterranean. The port played a key role in funnelling imports — e.g. foodstuffs, wild animals, marble and luxury goods — from across the Mediterranean and beyond to the citizens of Rome and was vital to the pre-eminence of the city in the Roman Mediterranean. But, what of the people who lived, worked and died there?

Diet at the docks: Living and dying at the port of ancient Rome
Aerial photo of the Portus Project excavations in 2009
[Credit: Portus Project]

In a study published in Antiquity, an international team of researchers present the results of the analysis of plant, animal and human remains, reconstructing both the diets and geographic origins of the Portus inhabitants. The findings suggest that the political upheaval following the Vandal sack of Rome in AD 455 and the 6th century wars between the Ostrogoths and the Byzantines may have had a direct impact on the food resources and diet of those working at Portus Romae.
Lead author, Dr Tamsin O’Connell of the Department of Archaeology, University of Cambridge said, «The human remains from the excavations at Portus belong to a local population involved in heavy, manual labour, perhaps the saccarii (porters) who unloaded cargoes from incoming ships. When looking isotopically at the individuals dating to between the early second to mid fifth centuries AD, we see that they have a fairly similar diet to the rich and middle-class people buried at the Isola Sacra cemetery just down the road. It is interesting that although there are differences in social status between these burial populations, they both have access to similar food resources. This contradicts what we see elsewhere in the Roman world at this time. But, later on, something changes.»

Dr O’Connell continues, «Towards the end of the mid fifth century we see a shift in the diet of the local populations away from one rich in animal protein and imported wheat, olive oil, fish sauce and wine from North Africa, to something more akin to a ‘peasant diet’, made up of mainly plant proteins in things like potages and stews. They’re doing the same kind of manual labour and hard work, but were sustained by beans and lentils»

Diet at the docks: Living and dying at the port of ancient Rome
Digital Reconstruction of Portus Romae
[Credit: Portus Project/Artas Media]

«This is the time period after the sack of the Vandals in AD 455. We’re seeing clear shifts in imported foods and diet over time that tie-in with commercial and political changes following the breakdown of Roman control of the Mediterranean. We are able to observe political effects playing out in supply networks. The politics and the resources both shift at the same time.»
Director of the University of Southampton’s Portus Project, Professor Simon Keay explained, «Our excavations at the centre of the port provide the first archaeological evidence of the diet of the inhabitants of Portus at a critical period in the history of Imperial Rome. They tell us that by the middle of the 5th century AD, the outer harbour basin was silting up, all of the buildings were enclosed within substantial defensive walls, that the warehouses were used for the burial of the dead rather than for storage, and that the volume of trade that passed through the port en route to Rome had contracted dramatically.»

«These developments may have been in some way related to the destruction wrought upon Portus and Rome by invading Vandals led by Gaiseric in AD 455, but may also be related to decreasing demand by the City of Rome, whose population had shrunk significantly by this date. These conclusions help us better understand major changes in patterns of production and trade across the Mediterranean that have been detected in recent years.»

Diet at the docks: Living and dying at the port of ancient Rome
1,700-year-old charred wheat grains from Portus Romae
[Credit: R. Ballantyne & L. Bonner]

Dr O’Connell concludes, «Are food resources and diets shaped by political ruptures? In the case of Portus, we see that when Rome was rich everybody, from the local elite to the dockworkers, was doing fine nutritionally. Then this big political rupture happens and wheat and other foodstuffs have to come from somewhere else. When Rome is on the decline, the manual labourers, at least, are not doing as well as previously.»

Source: University of Cambridge [June 12, 2019]



The short life of Must Farm

Must Farm, an extraordinarily well-preserved Late Bronze Age settlement in Cambridgeshire, in the East of England, drew attention in national and international media in 2016 as ‘Britain’s Pompeii’ or the ‘Pompeii of the Fens’. The major excavation was funded by Historic England and Forterra Building Products Ltd, which owns the Must Farm quarry.

The short life of Must Farm
Excavation of the Must Farm pile-dwelling settlement, showing the main body of the collapsed settlement
(looking east) in its river silt matrix [Credit: D. Webb]

Now for the first time, published in Antiquity, archaeologists from the Cambridge Archaeological Unit present a definitive timeframe to Must Farm’s occupation and destruction.

The short life of Must Farm
Scaffold platform above Must Farm’s ‘structure 1’
[Credit: D. Webb]

Site Director Mark Knight says, «It is likely that the settlement existed for only one year prior to its destruction in a catastrophic fire. The short history of Must Farm, combined with the excellent preservation of the settlement, means that we have an unparalleled opportunity to explore the daily life of its inhabitants.»
Living in the Fens

Must Farm is located within the silts of a slow-flowing freshwater river, with stilted structures built to elevate the living quarters above the water. This palaeochannel (dating from 1700-100 BC) was active for centuries prior to the construction of Must Farm (approx. 1100-800 cal BC), and a causeway was built across the river.

The short life of Must Farm
Material culture ‘footprint’ beneath structures 2 & 4 (scale = 1m)
[Credit: D. Webb]

«Although excavation of the river sediments associated with the causeway was limited, stratigraphically we can demonstrate that the that the causeway and the settlement are chronologically unconnected. The people who built the settlement, however, would have been able to see the rotting tops of the causeway piles during the time of the settlement’s construction,» Knight continues.

The short life of Must Farm
Pots recovered from the Bronze Age settlement at Must Farm Quarry
in Cambridgeshire [Credit: PA]

Excavations between 2009 and 2012 revealed the remains of nine logboats in the palaeochannel, in addition to fish weirs and fish traps — further evidence of the long history of occupation in the landscape.
Prehistoric Houses

The Must Farm houses are the ‘most completely preserved prehistoric domestic structures found in Britain’, visible as ‘hundreds of uprights or pile stumps, which together define the outline and internal settings of at least five stilted structures’ enclosed by a palisade with an internal walkway.

The short life of Must Farm
Artist’s reconstruction of Must Farm [Credit: Vicki Herring,
Cambridge Archaeological Unit]

The architecture reflects the conventions of the prehistoric British roundhouse, located in an unusual wetland setting. Uniquely, there is no evidence of repair to the structures, and strikingly, dendrochronological analysis has suggested that the timbers were still green when destroyed by fire.

The short life of Must Farm
Artist’s impression of an overhead view of Must Farm [Credit: Vicki Herring,
Cambridge Archaeological Unit]

The structures collapsed vertically, and the heavy roofs brought everything down with them into the sediment of the channel. A tragedy for the inhabitants, but serendipitous for archaeologists, as the fluvial silts have preserved ‘wooden artefacts, pottery sets, bronze tools and weapons, fabrics and fibres, querns, loom weights, spindle whorls, animal remains, plants and seeds, coprolites…’
A Year in the Life

Must Farm represents a routine dwelling in a rarely excavated fenland setting, which is incredibly valuable. It shows the typical patterns of consumption and deposition for this kind of site.

The short life of Must Farm
Top) thread/yarn wound around sticks/round dowels; bottom) a complete two-piece,
axe haft with Ewart Park-type socketed axe [Credit: D. Webb]

The team of archaeologists found over 180 fibre/textile items, 160 wooden artefacts, 120 pottery vessels, 90 pieces of metal work, and at least 80 glass beads.

The short life of Must Farm
Charred timber pulled from the site, showing the incredible preservation
after 3,000 years [Credit: Must Farm Project]

Some of the plant and animal remains found at Must Farm are rare for this period in British prehistory, including pike bones, sheep/goat dung, and currently unidentified entire charred tubers. Strikingly, most of the food sources, including wild boar and deer, are not from the wetlands.

The short life of Must Farm
Site location in the Flag Gen Basin (lidar data), with key sites marked (lidar data
from Environment Agency LIDAR Composite DTM 1m, licensed under the
Open Government Licence v3.0 [Credit: D. Horne & V. Herring]

Knight concludes, «We are only in the early stages of investigating the vast quantity of material from Must Farm, material which promises to reveal many more fascinating aspects of life in the fens 3,000 years ago.»

Source: University of Cambridge [June 12, 2019]



Fragment of statue base with Greek inscription from 2nd century found in Bulgaria’s...

A fragment with a Greek inscription, dating from the first decades of the second century CE, has been found at the Great Basilica site in Bulgaria’s second city Plovdiv.

Fragment of statue base with Greek inscription from 2nd century found in Bulgaria’s Plovdiv
Credit: podtepeto.com

The dig team headed by Zheni Tankova found a total of three fragments that probably were part of a large statue dedicated to a distinguished resident of Philippopolis (today’s Plovdiv).
In the late fourth or early fifth centuries, with the construction of the Basilica, the pedestal of the statue was re-used, broken up to become part of the support of the main paving of the atrium.

Fragment of statue base with Greek inscription from 2nd century found in Bulgaria’s Plovdiv

Fragment of statue base with Greek inscription from 2nd century found in Bulgaria’s Plovdiv
Credit: podtepeto.com

Epigraphist Professor Nikolai Sharankov, who examined the lettering on the stone slab, said: “It is very interesting that for the first time we have an inscription mentioning the ancient theatre directly. Prior to this, another inscription was found linking the Basilica to the theatre – a list of members of the Elders’ Council, including the name of its treasurer who built a loggia in the theatre,” Sharankov said.
He said that the new find was the second link between these two most significant sites in Philippopolis: “Fortunately, of the inscription, ‘ΘΕΑΤΡΩ[’ survived. Otherwise, it was part of a large masonry pedestal for a statue in honour of a prominent citizen of Philippopolis, honoured for his beneficence to the city. What can be seen is that he organised some celebrations in honour of all gods and goddesses and was probably honoured with a statue in the theatre,” Sharankov said.

Fragment of statue base with Greek inscription from 2nd century found in Bulgaria’s Plovdiv

Fragment of statue base with Greek inscription from 2nd century found in Bulgaria’s Plovdiv
Credit: podtepeto.com

The inscription dates from the first decades of the second century CE, the time of emperor Trajan or Hadrian, and was done in the same workshop that produced all the official inscriptions for the city during that time.

It can be concluded that this inscription, in honour of one of the most prominent citizens of the city, stood somewhere nearby before it was re-used during the construction of the Basilica in late antiquity.

“We hope there may be more fragments of the text in order to try to restore it more fully, as well as to understand the name of this person, about whom we have only two letters for now,” Sharankov said.

Source: The Sofia Globe [June 12, 2019]



Parts of new Doric monument found at Paestum

Removing what had become over the years a real jungle that covered the western side of the walls of Paestum, the archaeologists of the Archaeological Park came across a completely unexpected discovery: capitals, columns, cornices and triglyphs belonging to a Doric building in the city of temples.

Parts of new Doric monument found at Paestum
Credit: InfoCilento

The most surprising discovery is a panel, probably a metope, in sandstone decorated with three rosettes in relief, such as are also found in other Doric buildings built between the sixth and fifth centuries BC in Paestum and its territory.
The cleaning of the walls began a few days ago as part of a European project funded with structural funds and aimed at the restoration and redevelopment of the walls of ancient Paestum, about 5 km long.

Parts of new Doric monument found at Paestum
Credit: InfoCilento

The architectural elements, of extreme interest also for the presence of traces of plaster and red painting, seem to have been accumulated along the perimeter walls during agricultural works since the 1960s. They seem to belong to a smaller building — a small temple or a portico (stoà) — which would date back to the same period as the Tomb of the Diver and the Temple of Athena (end of the 6th/beginning of the 5th century BC).
As the director of the Paestum Archaeological Park, Gabriel Zuchtriegel, explains, the area has in the past provided a votive collection, with clay statues of female deities on a throne and ceramic fragments dating back to between the 6th and 3rd centuries BC. It is located in the vicinity of what was probably the kerameikos of Paestum, the craft district where the famous painted vases of the city were made.

Parts of new Doric monument found at Paestum
Credit: InfoCilento

«Now, somewhere between the artisan quarter and the city walls, there must have been our building, a real jewel of late archaic Doric architecture. The question remains: where exactly», said the Park’s director.

Source: Info Cilento [June 13, 2019]



2019 June 13 The Colors and Magnitudes of M13 Image Credit…

2019 June 13

The Colors and Magnitudes of M13
Image Credit & Copyright: Tolga Gumusayak, Robert Vanderbei

Explanation: M13 is modestly recognized as the Great Globular Star Cluster in Hercules. A ball of stars numbering in the hundreds of thousands crowded into a region 150 light years across, it lies some 25,000 light-years away. The sharp, color picture of M13 at upper left is familiar to many telescopic imagers. Still, M13’s Color vs Magnitude Diagram in the panel below and right, made from the same image data, can offer a more telling view. Also known as a Hertzsprung Russell (HR) diagram it plots the apparent brightness of individual cluster stars against color index. The color index is determined for each star by subtracting its brightness (in magnitudes) measured through a red filter from its brightness measured with a blue filter (B-R). Blue stars are hot and red stars are cool so that astronomical color index ranging from bluer to redder follows the relative stellar temperature scale from left (hot) to right (cool). In M13’s HR diagram, the stars clearly fall into distinct groups. The broad swath extending diagonally from the bottom right is the cluster’s main sequence. A sharp turn toward the upper right hand corner follows the red giant branch while the blue giants are found grouped in the upper left. Formed at the same time, at first M13’s stars were all located along the main sequence by mass, lower mass stars at the lower right. Over time higher mass stars have evolved off the main sequence into red, then blue giants and beyond. In fact, the position of the turn-off from the main sequence to the red giant branch indicates the cluster’s age at about 12 billion years.

∞ Source: apod.nasa.gov/apod/ap190613.html

Fast and furious: detection of powerful winds driven by a supermassive black hole

The supermassive black holes in the centres of many galaxies seem to have a basic influence on their evolution. This happens during a phase in which the black hole is consuming the material of the galaxy in which it resides at a very high rate, growing in mass as it does so. During this phase we say that the galaxy has an active nucleus (AGN, for active galactic nucleus).

Fast and furious: detection of powerful winds driven by a supermassive black hole
Black-hole winds sweep away the gas in galaxies
[Credit: Instituto de Astrofisica de Canarias]

The effect that this activity has on the host galaxy is known as AGN feedback, and one of its properties are galactic winds: this is gas from the centre of the galaxy being driven out by the energy released by the active nucleus. These winds can reach velocities of up to thousands of kilometres per second, and in the most energetic AGNs, for example the quasars, which can clean out the centres of the galaxies impeding the formation of new stars. It has been shown that the evolution of the star formation over cosmological timescales cannot be explained without the existence of a regulating mechanism.

To study these winds in quasars the EMIR infrared spectrograph on the Gran Telescopio Canarias (GTC) was used. EMIR is an instrument developed completely in the Instituto de Astrofisica de Canarias, which is designed to study the coolest and most distant objects in the universe by analysing infrared light. Since June 2016 this has been installed at a focus of the GTC, after going through an exhaustive test phase in the workshops of the Instrument Division of the IAC headquarters in La Laguna.

The data obtained since then has been used to produce several scientific articles of which the latest is a study of the obscured quasar J1509+0434, published in the journal Monthly Notices of the Royal Astronomical Society Letters and produced by an international team led by IAC researcher Cristina Ramos Almeida. This quasar is in the local universe, and is an analogue of the more distant and far more numerous quasars in which AGN feedback must be affecting in a major way the formation of new stars.

«EMIR has allowed us to study the winds of ionized and molecular gas from this quasar by using the infrared range. This analysis is very important because they don’t always show similar properties, which tells us a great deal about how these winds are produced and how they affect their host galaxies», explains Ramos Almeida. The study of this and other local quasars will allow us to understand what was happening in galaxies when they were younger and when they were forming their structures which we see today.

Based on the new data obtained with EMIR, the team has discovered that the ionized wind is faster than the molecular wind, reaching velocities of up to 1,200 km/s. However it would be the molecular wind which is emptying the gas reservoirs of the galaxy (up to 176 solar masses per year). «New observations with ALMA will let us confirm this estimate», explained Jose Acosta Pulido, a researcher at the IAC and co-author of this study.

The next step is to observe a complete sample of obscured nearby quasars with EMIR to study their ionized and molecular winds. We also want to investigate the stellar populations of their host galaxies. This will allow us to confirm directly the effect of AGN feedback on the evolution of the galaxies.

Source: Instituto de Astrofisica de Canarias [June 07, 2019]



Could climate change make Siberia more habitable?

Large parts of Asian Russia could become habitable by the late 21st century due to climate change, new research has found.

Could climate change make Siberia more habitable?
Credit: IOP Publishing

A study team from the Krasnoyarsk Federal Research Center, Russia, and the National Institute of Aerospace, USA, used current and predicted climate scenarios to examine the climate comfort of Asian Russia and work out the potential for human settlement throughout the 21st century. They published their results in Environmental Research Letters.

At 13 million square kilometres Asian Russia — east of the Urals towards the Pacific — accounts for 77 per cent of Russia’s land area. Its population, however, accounts for just 27 per cent of the country’s people and is concentrated along the forest-steppe in the south, with its comfortable climate and fertile soil.

«Previous human migrations have been associated with climate change. As civilisations developed technology that enabled them to adapt, humans became less reliant on the environment, particularly in terms of climate,» said the study’s lead author Dr Elena Parfenova, from the Krasnoyarsk Federal Research Center.

«We wanted to learn if future changes in climate may lead to the less-hospitable parts of Asian Russia becoming more habitable for humans.»

For their analysis, the team used a combination of 20 general circulation models (Coupled Model Intercomparison Project Phase 5) and two CO2 Representative Concentration Pathway scenarios — RCP 2.6 representing mild climate change and RCP 8.5 representing more extreme changes.

They applied the collective means of January and July temperatures and annual precipitation of the two scenarios to Asian Russia to find their respective effects on three climate indices that are important for human livelihood and well-being: Ecological Landscape Potential (ELP), winter severity, and permafrost coverage.

Dr Parfenova said: «We found increases in temperature of 3.4°C (RCP 2.6) to 9.1°C (RCP 8.5) in mid-winter; increases of 1.9°C (RCP 2.6) to 5.7°C (RCP 8.5) in mid-summer; and increases in precipitation of 60 mm (RCP 2.6) to 140 mm (RCP 8.5).

«Our simulations showed that under RCP8.5, by the 2080s Asian Russia would have a milder climate, with less permafrost coverage, decreasing from the contemporary 65 per cent to 40 per cent of the area by the 2080s.»

The researchers also found that even under the RCP 2.6 scenario, the ELP for human sustainability would improve in more than 15 per cent of the area, which could allow for a five-fold increase in the in the capacity of the territory to sustain and become attractive to human populations.

Dr Parfenova concluded: «Asian Russia is currently extremely cold. In a future warmer climate, food security in terms of crop distribution and production capability is likely to become more favourable for people to support settlements.

«However, suitable land development depends on the authorities’ social, political and economic policies. Lands with developed infrastructure and high agricultural potential would obviously be populated first.

«Vast tracts of Siberia and the Far East have poorly developed infrastructure. The speed these developments happen depends on investments in infrastructure and agriculture, which in turn depends on the decisions that should be made soon.»

Author: Simon Davies | Source: IOP Publishing [June 07, 2019]



Astronomers determine mass of small black hole at centre of nearby galaxy

If astronomers want to learn about how supermassive black holes form, they have to start small—really small, astronomically speaking.

Astronomers determine mass of small black hole at centre of nearby galaxy
Light echo measured from the central black hole in a dwarf galaxy NGC 4395. The time delay between the continuum
from the black hole’s accretion disk (blue light curve) and the hydrogen emission from orbiting gas clouds (red light
curve) is measured as ~80 min., providing the light travel time from the black hole to the gas emission region.
[Credit for NGC 4395 image: Adam Block/Mount Lemmon SkyCenter/University of Arizona;
Credit for accretion disk illustration: NASA/Chandra X-ray Observatory/M. Weiss]

In fact, a team including University of Michigan astronomer Elena Gallo has discovered that a black hole at the center of a nearby dwarf galaxy, called NGC 4395, is about 40 times smaller than previously thought. Their findings are published in the journal Nature Astronomy.

Currently, astronomers believe that supermassive black holes sit at the center of every galaxy as massive as or larger than the Milky Way. But they’re curious about black holes in smaller galaxies such as NGC 4395 as well. Knowing the mass of the black hole at the center of NGC 4395—and being able to measure it accurately—can help astronomers apply these techniques to other black holes.

«The question remains open for small or dwarf galaxies: Do these galaxies have black holes, and if they do, do they scale the same way as supermassive black holes?» Gallo said. «Answering these questions might help us understand the very mechanism through which these monster black holes were assembled when the universe was in its infancy.»

To determine the mass of NGC’s black hole, Gallo and her fellow researchers employed reverberation mapping. This technique measures mass by monitoring radiation thrown off by what’s called an accretion disk around the black hole. An accretion disk is a mass of matter collected by the gravitational pull of black holes.

As radiation travels outward from this accretion disk, it passes through another cloud of material farther out from the black hole that’s more diffuse than the accretion disk. This area is called the broad-line region.

When the radiation hits gas in the broad-line region, it causes atoms in it to undergo a transition. This means that the radiation bumps an electron out of the shell of an atom of hydrogen, for example, causing the atom to occupy a more energetic level of the atom. After the radiation passes, the atom settles back into its previous state. Astronomers can image this transition, which looks like a flash of brightness.

By measuring how long it takes for the accretion disk radiation to hit the broad-line region and cause these flashes, the astronomers can estimate how far the broad-line region is from the black hole. Using this information, they can then calculate the black hole’s mass.

«The distance is thought to depend on the black hole mass,» Gallo said. «The larger the black hole, the larger the distance and the longer you expect for light to be emitted from the accretion disk to hit the broad-line region.»

Using data from the MDM Observatory, the astronomers calculated that it took about 83 minutes, give or take 14 minutes, for radiation to reach the broad-line region from the accretion disk. To calculate the black hole mass, they also had to measure the intrinsic speed of the broad-line region, which is the speed at which the region cloud is moving under the influence of the black hole gravity. To do this, they took a high-quality spectrum with the GMOS spectrometer on GEMINI North telescope.

By knowing this number, the speed of the broad-line region, the speed of light and what’s called the gravitational constant, or a measure of gravitational force, the astronomers were able to determine that the black hole’s mass was about 10,000 times the mass of our sun—about 40 times lighter than previously thought. This is also the smallest black hole found via reverberation mapping.

«This regime of dwarf galaxies is largely unexplored when it comes to the properties of their nuclear black holes,» Gallo said. «We don’t even know if every galaxy has a black hole. This adds a new member to the family of black holes we have information about.»

This information also could help astronomers understand how much larger black holes shape the galaxies they occupy. A field called black hole feedback explores how black holes affect the properties of their host galaxies at much larger scales than their gravitational pull should reach.

«There’s no reason why stars that live at orders of magnitude larger than the area where black hole gravity dominates should even know that there’s a black hole in their galaxy, but somehow they do,» Gallo said. «Black holes somehow shape the galaxy they live in on very large scales, and because we don’t know much about smaller galaxies with their smaller black holes, we don’t know whether that’s true all the way down. With this measurement, we can add more information to this relationship.»

Source: University of Michigan [June 10, 2019]



New study dramatically narrows the search for advanced life in the universe

Scientists may need to rethink their estimates for how many planets outside our solar system could host a rich diversity of life.

New study dramatically narrows the search for advanced life in the universe
Credit: Dion Lee/Vox

In a new study, a UC Riverside-led team discovered that a buildup of toxic gases in the atmospheres of most planets makes them unfit for complex life as we know it.

Traditionally, much of the search for extraterrestrial life has focused on what scientists call the «habitable zone,» defined as the range of distances from a star warm enough that liquid water could exist on a planet’s surface. That description works for basic, single-celled microbes — but not for complex creatures like animals, which include everything from simple sponges to humans.

The team’s work, published in The Astrophysical Journal, shows that accounting for predicted levels of certain toxic gases narrows the safe zone for complex life by at least half — and in some instances eliminates it altogether.

«This is the first time the physiological limits of life on Earth have been considered to predict the distribution of complex life elsewhere in the universe,» said Timothy Lyons, one of the study’s co-authors, a distinguished professor of biogeochemistry in UCR’s Department of Earth and Planetary Sciences, and director of the Alternative Earths Astrobiology Center, which sponsored the project.

«Imagine a ‘habitable zone for complex life’ defined as a safe zone where it would be plausible to support rich ecosystems like we find on Earth today,» Lyons explained. «Our results indicate that complex ecosystems like ours cannot exist in most regions of the habitable zone as traditionally defined.»

New study dramatically narrows the search for advanced life in the universe
Three planets orbiting TRAPPIST-1 fall within that star’s habitable zone
[Credit: R. Hurt/ NASA/JPL-Caltech]

Using computer models to study atmospheric climate and photochemistry on a variety of planets, the team first considered carbon dioxide. Any scuba diver knows that too much of this gas in the body can be deadly. But planets too far from their host star require carbon dioxide — a potent greenhouse gas — to maintain temperatures above freezing. Earth included.

«To sustain liquid water at the outer edge of the conventional habitable zone, a planet would need tens of thousands of times more carbon dioxide than Earth has today,» said Edward Schwieterman, the study’s lead author and a NASA Postdoctoral Program fellow working with Lyons. «That’s far beyond the levels known to be toxic to human and animal life on Earth.»

The new study concludes that carbon dioxide toxicity alone restricts simple animal life to no more than half of the traditional habitable zone. For humans and other higher order animals, which are more sensitive, the safe zone shrinks to less than one third of that area.

What is more, no safe zone at all exists for certain stars, including two of the sun’s nearest neighbors, Proxima Centauri and TRAPPIST-1. The type and intensity of ultraviolet radiation that these cooler, dimmer stars emit can lead to high concentrations of carbon monoxide, another deadly gas. Carbon monoxide binds to hemoglobin in animal blood — the compound that transports oxygen through the body. Even small amounts of it can cause the death of body cells due to lack of oxygen.

Carbon monoxide cannot accumulate on Earth because our hotter, brighter sun drives chemical reactions in the atmosphere that destroy it quickly. Although the team concluded recently that microbial biospheres may be able to thrive on a planet with abundant carbon monoxide, Schwieterman emphasized that «these would certainly not be good places for human or animal life as we know it on Earth.»

New study dramatically narrows the search for advanced life in the universe
The habitable zone for complex life (blue) is highly restricted relative to the zone defined by the potential
for liquid water, due to toxic buildup of carbon dioxide (yellow) and carbon monoxide (red).
This narrowerzone excludes many exoplanets including Proxima Centauri b and TRAPPIST-1
planets e, f and g (black dots) [Credit: Christopher Reinhard/Georgia Tech]

Scientists have confirmed nearly 4,000 planets orbiting stars other than the sun, but none of them will be possible to visit in person. They are simply too far away. Closest is Proxima Centauri b, which would take 54,400 years for current spacecraft to reach. Using telescopes to detect abundances of certain gases in their atmospheres is one of the only ways to study these so-called exoplanets.

«Our discoveries provide one way to decide which of these myriad planets we should observe in more detail,» said Christopher Reinhard, a former UCR graduate student now an assistant professor at the Georgia Institute of Technology, co-author of this study, and co-leader of the Alternative Earths team. «We could identify otherwise habitable planets with carbon dioxide or carbon monoxide levels that are likely too high to support complex life.»

Findings from the team’s previous work is already informing next-generation space missions such as NASA’s proposed Habitable Exoplanet Observatory. For example, because oxygen is essential to complex life on Earth and can be detected remotely, the team has been studying how common it may be in different planets’ atmospheres.

Other than Earth, no planet in our solar system hosts life that can be characterized from a distance. If life exists elsewhere in the solar system, Schwieterman explained, it is deep below a rocky or icy surface. So, exoplanets may be our best hope for finding habitable worlds more like our own.

«I think showing how rare and special our planet is only enhances the case for protecting it,» Schwieterman said. «As far as we know, Earth is the only planet in the universe that can sustain human life.»

Source: University of California — Riverside [June 10, 2019]



Breakthrough in the discovery of DNA in ancient bones buried in water

During the Iron Age around 300 AD something extraordinary was initiated in Levänluhta area in Isokyrö, SW Finland. The deceased were buried in a lake, and this habit was continued for at least 400 years. When trenches were dug in the local fields in mid-1800’s skulls and other human bones were surfacing. These bones had been preserved almost intact in the anoxic, ferrous water. Archaeologists, historians and locals have been wondering about these finds for over 150 years now.

Breakthrough in the discovery of DNA in ancient bones buried in water
Levänluhta Spring in Isokyrö, SW Finland 
[Credit: Anna Wessman, 2019]

In 2010, a multidisciplinary research group at the University of Helsinki decided to re-investigate the mystery of Levänluhta. The site, thought to be e.g. a sacrificial spring, is exceptional even in global scale and has yielded altogether c. 75 kg human bone material.

The research group, led by docent Anna Wessman, had an ambitious aim: to find who the deceased buried in Levänluhta were, and why they were exceptionally buried under water so far from dwelling sites.

Now, after several years of scientific work, the group reports their results in the journal Nature. The results are part of a more extensive international study shedding light on the colonization and population history of Siberia with DNA data from ancient — up to 31 000 years old — human bones.

«In our part, we wanted especially to find out the origins of the Iron Age remains found from Levänluhta,» says the group leader Anna Wessman.

New results with DNA sequencing technology

This was investigated using cutting edge ancient DNA sequencing technology, which Department of Forensic Medicine is interested in due to the forensic casework performed at the department. Professor Antti Sajantila explains that the early phases of this project were demanding.

«Unability to repeat even our own results was utterly frustrating,» Sajantila tells about the first experiments in the laboratory.

The methods were developing rapidly during the international co-operation, and ultimately the first Finnish results were shown to be accurate. Yet, it was surprising that the genomes of three Levänluhta individuals clearly resembled those of the modern Sámi people.

«We understood this quite early, but it took long to confirm these findings,» tells docent Jukka Palo.

Locals or by-passers?

The results were suggesting that the Isokyrö region was inhabited by Sámi people in ancient times — according to carbon datings the bones belonged to individuals that had died 500 — 700 AD. This would be a concrete proof of Sámi in southern Finland in the past. But were the people locals, recent immigrants or haphazard by-passers? To find out, other techniques than DNA were needed. The solution lied in the enamel of teeth.

Curator Laura Arppe from the Finnish Museum of Natural History tells that strontium isotopes found in the enamel strongly suggest that the individuals grew up in the Levänluhta region.

The current genomes of the people in Finland carry both eastern Uralic and western Scandinavian components, and the genome of one the Levänluhta individuals examined had clear ties to present day Scandinavians.

As a whole the replacement of the Sámi people in southern and central Finland reflects the replacement processes in Siberia, clarified in the present article. This has probably been a common feature in the Northern latitudes.

«The Levänluhta project demands further studies, not only to broaden the DNA data but also to understand the water burials as a phenomenon. The question «Why?» still lies unanswered,» ponders the bone specialist, docent Kristiina Mannermaa.

Source: University of Helsinki [June 11, 2019]



21st century archaeology rediscovers historical Cordoba

On the land where Cordoba is located in the 21st century, two cities coexisted in the past, each on a hill. An Iberian city was located where Cruz Conde Park lies today, and a Roman city, which was founded at a later time, was located about 500 meters away. Archaeology has had to depend upon geological studies up to now in order to determine how the city developed throughout history, but now, thanks to LiDAR technology, 3D images have been obtained that show what the land was like where Cordoba lies before humans arrived.

21st century archaeology rediscovers historical Cordoba
View of the Roman bridge on Guadalquivir river and the Great Mosque (Mezquita Cathedral), Cordoba
[Credit: Shutterstock]

Antonio Monterroso, an Art History, Archaeology and Music Department researcher at the University of Cordoba, used data from a specific LiDAR flight for the first time. This flight was performed by the National Geographic Institute (abbreviated to IGN in Spanish) in 2016 and covered all of Spain. The data was used to analyze the morphology of an already built city.
These data are publicly accessible and have led to the aerial detection of several archaeological sites outside of urban enclaves in Spain, but this tool’s potential was underestimated when it came to analyzing historical cities.

Aerial laser LiDAR technology is a recent development. A small plane flies over an area and casts millions of points of light and uses them to calculate the height at which objects they collide with are located. These objects could be trees, mountains or buildings. This provides a three-dimensional image of the area being studied.

21st century archaeology rediscovers historical Cordoba
Thhe ancient geomorphology of the city of Cordoba
[Credit: Antonio Monterroso-Checa]

Cordoba is a built-up city, so these data apparently do not provide any archaeological information, due to the fact that most ruins are buried underneath new buildings. However, if these data are filtered and only the ones that hit the ground are chosen, while disregarding the points that collided with urban features, they can be used to generate a 3D picture of the actual land where the city lies.
In this way, Antonio Monterroso Checa was able to digitally recreate the geomorphology of the area where Cordoba is located before it was covered with buildings. In the images, one can clearly see how first the Iberian city and later the Roman one both took advantage of the shape of the land in order to build their settlements.

The former was located on a hill, which is named Los Quemados Hill today, while the latter was built on a less steep hill farther to the northeast. The images also show how these two settlements were located next to the old Guadalquivir riverbed, which was farther north than it is today. In Roman and medieval times, once the river took its current shape, the city spread over what had once been the old riverbed, and high foundations and fortifications were built to avoid flooding.

21st century archaeology rediscovers historical Cordoba
The three historical settlements of Cordoba. The Iberian, Roman and medieval city and the new extension
of the medieval city from the 12th century. Orthoimage of 2016 acquired by IGN
[Credit: ©OrtoPNOA 2016 CC-BY 4.0/UCO]

Up until now, the traces of this old Guadalquivir riverbed had only been revealed by means of archaeologial studies that detected signs of flooding in the area and the presence of underground sand. Thanks to Monterroso’s research, we can now see this evidence digitally in a clearer and more graphic way.
This is the first part of a much broader scope of research that Antonio Monterroso is performing on the province of Cordoba. He is currently immersed in studying LiDAR data from the IGN around the Medina Azahara historical site and its surroundings. The aim of this work is to continue to uncover new information about the world heritage that the historical city of Cordoba holds.

The findings are published in Geosciences.

Source: University of Cordoba [June 11, 2019]




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