пятница, 21 июня 2019 г.

Coincidence or master plan?

All living things — from the simplest animal and plant organisms to the human body — live closely together with an enormous abundance of microbial symbionts, which colonise the insides and outsides of their tissues. The functional collaboration of host and microorganisms, which scientists refer to as a metaorganism, has only recently come into the focus of life science research. Today we know that we can only understand many of life’s processes in connection with the interactions between organism and symbionts. The Collaborative Research Centre (CRC) 1182 «Origin and Function of Metaorganisms» at Kiel University (CAU) aims to understand the communication and the functional consequences of host-microbe relationships.

Coincidence or master plan?
The scientists applied the new theoretical approach to a range of model organisms, e.g. threadworms or mice,
which are investigated in the CRC 1182 at Kiel University [Credit: Science Communication Lab]

A key issue for the researchers at the CRC 1182 is how the composition of an organism’s microbiome forms during its individual development. It is still unclear as to whether the microbial community composition is more governed by a functional selection process or if random processes dominate. In order to examine the microbiome composition, a research team from the CAU’s CRC 1182 and the Max Planck Institute for Evolutionary Biology in Plön (MPI-EB) has now applied the theory of the so-called «neutral metaorganism» to an entire spectrum of model organisms, from very simple creatures to complex vertebrates. The scientists from Kiel and Plön published their findings yesterday in the journal PLOS Biology.

The null model of evolutionary theory

Theoretical models offer one way to make the highly complex, individual microbiome composition manageable. A fundamental model in evolutionary research is the so-called neutral null model. This is used to predict how populations would develop without any selection pressure whatsoever. The research team at the CRC 1182 has now applied this model to several model organisms from threadworms to house mice and compared the predictions with experimentally collected data.

«Theory and experimental data match surprisingly well for many organisms. The predicted composition in the house mouse, for example, is found in the actual microbial species community,» summarised Dr Michael Sieber, research associate at the MPI-EB and member of the CRC 1182. «t is possible that selection plays a lesser role in the microbiome’s composition than we previously assumed, while this does not mean that the microbiome has no important functions for the organism, it could be an indication that many different compositions of the microbiome can perform these functions equally well. And which specific composition actually forms in a single organism is then driven by chance.»

A map for further exploration of the microbiome

The researchers did notice some significant deviations between the neutral model and the real compositions of the microbiome, however. For example, individual bacterial species in the mouse microbiome did not match the neutral prediction. And the microbial species composition of the Caenorhabditis elegans thread worm did not match the neutral model at all.

«We assume that these deviations between model and reality could indicate specific functions of certain microorganisms,» Sieber emphasised. Investigating the systematic deviations from the neutral model therefore holds the potential to discover key functions of certain bacterial species within the microbiome.
First explanations for the deviations from the neutral model are already being discussed. Some non-neutral bacteria in the mouse microbiome, for example, are involved in digestion and their presence may therefore be the result of a targeted selection process. On the other hand, Caenorhabditis elegans, with its very fast generational change, might not live long enough to develop a stable, mainly neutral composition of its microbiome.

«The model of the neutral metaorganism therefore provides an important theoretical basis for further functional analyses of microbiome compositions across the entire spectrum of the model organisms investigated in our Collaborative Research Centre,» said CRC 1182 spokesperson Prof. Thomas Bosch.

Source: Kiel University [June 20, 2019]



Do ice cores help to unravel the clouds of climate history?

For the first time, an international research team led by the Leibniz Institute for Tropospheric Research (TROPOS) has investigated atmospheric ice nucleating particles (INPs) in ice cores, which can provide insights on the type of cloud cover in the Arctic over the last 500 years. These INPs play an important role in the formation of ice in clouds and thus have a major influence on the climate. So far, however, there are only a few measurements that date back only a few decades. The new method could help to obtain information about historical clouds from climate archives and thus close large gaps in knowledge in climate research.

Do ice cores help to unravel the clouds of climate history?
An ice core [Credit: NASA’s Goddard Space Flight Center/Ludovic Brucker]

The team from TROPOS, the University of Copenhagen, the University of Bern and the Paul Scherrer Institute writes in the journal Geophysical Research Letters that findings on variations in the concentrations of ice nucleating particles in the atmosphere over the past centuries would help to better understand future climate changes.

Climate archives are important for reconstructing the past climate and making statements about the development of the climate in the future. In Europe, the weather has only been observed and recorded regularly for around 300 years. For the time before and for locations without a weather station, however, research depends on conclusions from natural archives. Paleoclimate research uses a wide variety of natural archives such as tree rings, ice cores or sediments.

In recent decades, a number of methods have been developed and refined that use indirect indicators (climate proxies) to draw conclusions about climate factors such as temperature, precipitation, volcanic eruptions and solar activity. Clouds are responsible for precipitation, among other things, but they are very elusive and therefore difficult to study. But the number, type and extent of clouds and their ice content have a big influence on the radiation budget of the atmosphere, the temperature on the ground and precipitation, and information about parameters affecting clouds are hence important for climate reconstruction.

A method how to improve our knowledge about clouds and their role in climate history is now presented by an international research team from Germany, Denmark and Switzerland. According to them, the team has reconstructed the concentrations of ice nucleating particles (INP) from ice cores for the first time. These measurements could be used to reconstruct cloud cover in the future. «Ice formation in mixed-phase clouds is mainly caused by heterogeneous ice formation, i.e. INP are necessary to stimulate the freezing of supercooled cloud droplets.

The number and type of these particles therefore influence precipitation, lifetime and radiation properties of the clouds. In the laboratory, we were able to show that two types of particles are particularly suitable for this purpose: Mineral dust from the soil as well as various biological particles such as bacteria, fungal spores or pollen,» explains Dr. Frank Stratmann, head of the clouds working group at TROPOS.

Ice cores are often used to reconstruct various climate parameters such as temperature, precipitation or volcanic eruptions over thousands of years. For the now published study, the team was able to draw on parts of two ice cores from the Arctic: The core «Lomo09» was drilled on the Lomonosovfonna glacier on Svalbard at an altitude of 1200 metres in 2009.

The ice core «EUROCORE» was elaborately extracted in 1989 from the summit of the Greenland Ice Sheet at an altitude of over 3000 metres. The frozen samples of these cores were sent to Leipzig, where they were now examined for INP. Small samples of the ice were melted and the melt water divided into many small drops of 1 and 50 microliters. These drops were placed in two experimental setups, each with almost 100 tiny troughs, and were then cooled down in a controlled manner. These setups were already used in previous studies: Both, LINA (Leipzig Ice Nucleation Array) and INDA (Ice Nucleation Droplet Array), are instruments in which the many drops of water are cooled in a controlled manner.

Through a glass window it can be observed from above at which temperature how many drops freeze. The number of frozen drops is then converted into the concentration of ice nucleating particles. «In 2015 US-American researchers derived atmospheric INP concentrations from snow and precipitation water. What works for precipitation should also work for ice samples was our approach. And so we were the first to show that historical ice nuclei concentrations can also be extracted from the ice cores,» says Markus Hartmann of TROPOS, who carried out the investigations as part of his doctoral thesis.

Do ice cores help to unravel the clouds of climate history?
INDA (Ice Nucleation Droplet Array) is a instrument in which the many drops of water are cooled in a controlled manner.
 Through a glass window it can be observed from above at which temperature how many drops freeze.
The number of frozen drops is then converted into the concentration of ice nucleating particles
[Credit: Heike Wex, TROPOS]

This opens up new possibilities for paleoclimate research. Since the 1930s, countless ice cores have been extracted from glaciers all over the world and the climate of the past has been reconstructed. The Information on the cloud phase (i.e. if it contains ice or and or liquid water) was not available. The study by polar and atmospheric researchers is a first step in this direction.

Since the team did not have a continuous ice core available, it could only reconstruct the ice nucleating particles from individual years of the period 1735 to 1989 on Greenland and 1480 to 1949 on Svalbard. Overall, there was no trend in the ice nucleating particles over the last half millennium.

«However, the Arctic has only been warming dramatically for about 25 years. The ice analyzed now was formed before this strong warming began. Both measurements of a continuous ice core and of newer ice would therefore be desirable,» adds Markus Hartmann.

The fact that mankind has caused global warming through its emissions is undisputed among researchers. However, it is unclear how much the clouds in the atmosphere have been changed as a result. Researchers therefore also hope to gain important insights from investigations into ice nucleating particles in the air.

In autumn/winter 2016, a team from the University of Beijing, TROPOS, the University of Gothenburg and the Chinese Academy of Sciences measured the concentrations of ice nucleating particles in the air of the Chinese capital Beijing. However, they were unable to prove any connection with the high level of air pollution there.

«We therefore assume that the ice nucleating particles in Beijing originate more from natural sources such as dust storms or the biosphere, both of which are known as sources of ice nucleating particles, than from anthropogenic combustion processes,» says Dr. Heike Wex of TROPOS. «But this is a snapshot of one place and the indirect influence of man should not be forgotten: Changes in land use or droughts have an impact on dust in the atmosphere and on the biosphere, which in turn can lead to changes in clouds».

In order to better understand the effects of humanity on the atmosphere, cloud researchers measure both at the hotspots of air pollution such as the metropolises of emerging countries and in comparatively clean regions such as the polar regions. So far relatively little is known about the quantity, properties and sources of ice nucleating particles in the Arctic, although they are an important factor in cloud formation and thus for the climate there. Especially long time series with monthly or weekly time resolution are practically non-existent, but essential to investigate seasonal effects.

In the journal Atmospheric Chemistry and Physics, an Open Access journal of the European Geosciences Union (EGU), an international team, also led by TROPOS, recently published an overview of the seasonal variations in ice nuclei concentrations in the Arctic.

Do ice cores help to unravel the clouds of climate history?
LINA (Leipzig Ice Nucleation Array) is a instrument in which the many drops of water are cooled in a controlled manner.
Through a glass window it can be observed from above at which temperature how many drops freeze.
The number of frozen drops is then converted into the concentration of ice nucleating particles
 [Credit: Heike Wex, TROPOS]

Samples from four research stations in the Arctic from 2012/2013 and 2015/2016 were investigated in the Leipzig Cloud Laboratory of TROPOS: Alert in Canada, Ny-Ålesund on Spitsbergen (Norway), Utqiagvik (Barrow) in Alaska (USA) and Villum (Station Nord) in Greenland (Denmark).

«This gives us an overview of the variations between the seasons: Most abundant are ice nucleating particles in the air from the end of spring until the beginning of autumn, the least are found in winter and at the beginning of spring. This influences how the type of cloud cover in the Arctic changes during the year and thus the influence of clouds on Arctic warming,» explains Heike Wex.

Researchers hope that the studies will lead to better predictions on climate change, as climate models are currently unable to adequately reflect the warming of the Arctic, which will lead to uncertainties ranging from rising sea levels to regional climate changes in Europe.

The complex feedback processes between biosphere and climate will also be part of the MOSAiC expedition: In September 2019, the German research icebreaker Polarstern, led by the Alfred Wegener Institute (AWI), will drift through the Arctic Ocean for one year.

Supplied by additional icebreakers and aircraft, a total of 600 people from 17 countries will take part in the MOSAiC expedition. Together with an international partner, the AWI is responsible for the five main research areas: sea ice physics and snow cover, processes in the atmosphere and in the ocean, biogeochemical cycles and the Arctic ecosystem.

TROPOS will play a leading role in two central measurements: Firstly, a remote sensing container for the entire ice drift will continuously explore the vertical aerosol and cloud distribution using lidar, radar and microwave radiometers. On the other hand, a tethered balloon will measure the Arctic boundary layer as accurately as possible during a flight section.

Both measurements allow more or less the direct detection of the vertical distribution of the ice nucleating particles. In addition, TROPOS will again investigate the surface microlayer of the sea and melt ponds, which is likely to be a major source of ice nucleating particles in the Arctic.

Since 2016, the Collaborative Research Centre TR172 «Arctic Amplification» of the German Research Foundation (DFG) has been investigating the reasons why the Arctic warms much more than the rest of the Earth. In addition to the University of Leipzig, the research network also includes the universities of Bremen and Cologne, the Alfred Wegener Institute, the Helmholtz Centre for Polar and Marine Research (AWI) and the Leibniz Institute for Tropospheric Research (TROPOS) in Leipzig. Tilo Arnhold

Source: Leibniz-Institut für Troposphärenforschung [June 20, 2019]



Slime travellers: Earth’s oldest mobile animals

New UC Riverside-led research settles a longstanding debate about whether the most ancient animal communities were deliberately mobile. It turns out they were, because they were hungry.

Slime travellers: Earth's oldest mobile animals
Ancient Dickinsonia fossil unearthed in the Australian outback
[Credit: Scott Evans/UCR]

«This is the first time in the fossil record we see an animal moving to get food,» said study lead Scott Evans, a UCR paleontology doctoral candidate.

Evans’ team demonstrated that the 550-million-year-old ocean-dwelling creatures moved on their own rather than being pushed around by waves or weather. The research answers questions about when, why and how animals first developed mobility.

The team searched for evidence of movement in more than 1,300 fossils of Dickinsonia, dinner-plate-shaped creatures up to a meter long that lived and fed on a layer of ocean slime.

Details of the team’s analysis were published this month in the journal Geobiology. It found that Dickinsonia move like worms, constricting and relaxing their muscles to go after their next meal of microorganisms.

Dickinsonia were first discovered in the 1940s and since then, scientists have debated whether the fossils showed evidence of self-directed movement. To test this, it was crucial that Evans be able to analyze how multiple creatures living in the same area behaved relative to one another.

Evans and study co-author Mary Droser, a UCR professor of paleontology, reasoned that if Dickinsonia were riding waves or caught in storms, then all the individuals in the same area would have been moved in the same direction. However, that isn’t what the evidence shows.

«Multiple fossils within the same community showed random movement not at all consistent with water currents,» Evans said.

Slime travellers: Earth's oldest mobile animals
Fossil beds of the Nilpena National Heritage Ediacara site
[Credit: Scott Evans/UCR]

Critically, Evans was able to use fossil communities in the Australian outback unearthed by Droser and paper co-author James Gehling of the South Australian Museum. The duo systematically excavated large bed surfaces containing as many as 200 Dickinsonia fossils, allowing Evans to test whether the groups of the animals moved in the same or different directions, Evans said.

The team also analyzed the directions traveled by individual Dickinsonia.

«Something being transported by current should flip over or be somewhat aimless,» Evans said. «These movement patterns clearly show directionality based on the animals’ biology, and that they preferred to move forward.»

Future studies at UCR will try to determine what Dickinsonia bodies were made of. «The tissues of the animals are not preserved, so it’s not possible to directly analyze their body composition,» he said. «But we will look at other clues they left behind.»

Understanding Dickinsonia’s capabilities offers insight not only into the evolution of animal life on Earth, but also about the Earth itself and possibly about life on other planets.

«If we want to search for complex life on other planets, we need to know how and why complex life evolved here,» Evans said. «Knowing the conditions that enabled large mobile organisms to move during the Ediacaran era, 550 million years ago, gives us a clue about the habitable zone elsewhere.»

That Dickinsonia could move helps confirm a large amount of oxygen was available in Earth’s oceans during that time period, since it would have been required to fuel their movement. In a related study, Evans explored a spike in ocean oxygen levels during the Ediacaran period. Later, when oxygen levels dropped, Evans said that Dickinsonia — and things like them — went extinct.

Source: University of California — Riverside [June 20, 2019]



Mammals and their relatives thrived, diversified during so-called ‘Age of Dinosaurs,’...

Paleontologists are trying to dispel a myth about what life was like when dinosaurs roamed the Earth. The false narrative has wormed its way into books, lectures and even scientific papers about this long-ago era.

Mammals and their relatives thrived, diversified during so-called ‘Age of Dinosaurs,’ researchers show
Illustration of Alphadon, a small marsupial relative from the Cretaceous Period. Alphadon is representative
of the type of small, primarily insect-eating ancestors of the three major ecological radiations of mammaliaforms
— giving rise to lineages that have diverse diets and forms of locomotion [Credit: Misaki Ouchida]

The myth’s focus isn’t on dinosaurs. Its main characters are ancient mammals and their relatives, which together are known as mammaliaforms. According to the myth, a world crowded with dinosaurs left little room for mammaliaforms. As a result, mammals and their kin remained tiny, mouse-like and primitive. The myth posits that mammals didn’t evolve diverse shapes, diets, behaviors and ecological roles until the K-Pg mass extinction event 66 million years ago killed off the dinosaurs and “freed up” space for mammals.

“This is a very old idea, which makes it very hard to defeat,” said David Grossnickle, a postdoctoral researcher in the Department of Biology at the University of Washington. “But this view of mammaliaforms simply doesn’t stand up to what we and others have found recently in the fossil record.”

Grossnickle is the lead and corresponding author of a review article published in Trends in Ecology & Evolution that summarizes the latest fossil evidence for an alternative view: Mammals and their relatives have actually undergone three significant “ecological radiations” in their history. In evolutionary biology, a radiation occurs when a particular lineage invades and adapts to new ecological niches. In each of the radiations discussed in the review, mammaliaforms diversified from insect-chomping, rodent-like ancestors and adapted to a variety of ecological niches. New species arose that, for example, could climb, glide or burrow — and ate more specialized diets of meat, leaves or shellfish.

Two of these three ecological radiations of mammailaforms occurred during the Jurassic and Cretaceous periods when dinosaurs were thriving, according to Grossnickle and co-authors Stephanie Smith of the Field Museum in Chicago and Greg Wilson, a UW associate professor of biology and curator of vertebrate paleontology at the UW’s Burke Museum of Natural History & Culture.

The co-authors summarize the three ecological radiations, each of which involved different groups of mammaliaforms:

— The oldest mammaliaform ecological radiation ran from 190 to 163 million years ago in the early-to-mid Jurassic Period — amid the breakup of the supercontinent Pangaea — and involved the first true mammals and their closest relatives.

— A second ecological radiation of mammals began 90 million years ago in the Late Cretaceous Period, shortly after flowering plants evolved, and ended at the K-Pg mass extinction event 66 million years ago.

— The Paleocene-Eocene radiation began 66 million years ago around the time of the K-Pg event and ended about 34 million years ago, and led to the establishment of all the major lineages of placental and marsupial mammals alive today.

Mammals and their relatives thrived, diversified during so-called ‘Age of Dinosaurs,’ researchers show
Illustration of Didelphodon, a marsupial relative from the Late Cretaceous with the strongest
pound-for-pound bite force of any known mammal [Credit: Misaki Ouchida]

Each ecological radiation generated new varieties of mammaliaforms from more primitive, insect-eating, rodent-like ancestors. Many of the diverse forms that arose during the Jurassic and Cretaceous resemble species alive today, such as badgers, flying squirrels and even anteaters. But these dinosaur-era mammaliaforms are not the direct ancestors of their modern counterparts.

“These same ecological adaptations — for gliding, climbing, eating diverse diets — have evolved repeatedly in the history of mammals and their close relatives,” said Grossnickle.

Mammaliaforms that arose during the Jurassic radiation included the semi-aquatic, beaver-like Castorocauda; Maiopatagium, which likely resembled today’s flying squirrels; and the tree-climbing Henkelotherium. These lineages died out by the mid-Cretaceous Period — a time of general decline for early mammals and their relatives, likely due to climate change and the relatively rapid turnover of whole ecosystems.

The Late Cretaceous ecological radiation followed this period of decline, and saw the rise of new forms of mammals. These included the badger-sized Didelphodon, a marsupial relative with the strongest pound-for-pound bite force of any known mammal, as well as Vintana, a herbivore with some skull features similar to sloths. These diverse groups of mammals perished alongside dinosaurs in the K-Pg mass extinction.

“The presence of this diversity of mammaliaforms in the Jurassic and Cretaceous overturns a classical interpretation of how mammals evolved,” said Wilson. “This new interpretation was really made possible by new fossil discoveries over the past two decades in places like China and Madagascar.”

The Paleocene-Eocene radiation of mammals, which began around the time of the K-Pg event, generated the ancestors of today’s marsupial and placental mammals – from kangaroos and zebras to blue whales and humans. This radiation’s strong connection to today’s mammals may explain how the myth arose that mammals remained static and primitive in the time of the dinosaurs, according to Grossnickle.

“But focusing on the Paleocene-Eocene radiation gives a distorted view of the history of mammals,” said Grossnickle. “It ignores many of the other groups of mammals and their relatives that were diversifying millions of years before then.”

Fossil discoveries over the past quarter century support the view summarized by Grossnickle and co-authors. Dinosaur-era mammaliaforms that were once known by only a single tooth or a few bone fragments are now represented by more-complete skeletons, which show the diversity in body shape, size, locomotion and diet.

“Now we can start to see the huge diversity of mammals and their relatives who lived alongside the dinosaurs,” said Grossnickle.

Author: James Urton | Source: University of Washington [June 20, 2019]



Y chromosomes reveal population boom and bust in ancient Japan

Researchers at the University of Tokyo conducted a census of the Japanese population around 2,500 years ago using the Y chromosomes of men living on the main islands of modern-day Japan. This is the first time analysis of modern genomes has estimated the size of an ancient human population before they were met by a separate ancient population.

Y chromosomes reveal population boom and bust in ancient Japan
Left: Male skull of the late Jōmon Period, excavated at Miyano Kaizuka, Iwate Prefecture;
Right: Skull of immigrant type Yayoi people (man) from Futatsukayama ruins,
Saga Prefecture [Credit: Momotarou2012/WikiCommons]

«Evidence at archaeological dig sites has been used to estimate the size of ancient human populations, but the difficulty and unpredictability of finding those sites is a big limitation. Now we have a method that uses a large amount of modern data,» said Associate Professor Jun Ohashi, an expert in human evolutionary genetics and leader of the research team that performed the analysis.

Archaeological mystery

The current theory on human migrations into Japan is that the original inhabitants, the Jomon people, were met about 2,500 years ago by a separate group coming mainly from the Korean Peninsula, the Yayoi people.

Archaeologists have identified fewer Jomon sites from the Late Jomon Period, the era immediately before the Yayoi arrival. Global temperatures and sea levels dropped during that period, which could have made life more difficult for the hunter-gatherer Jomon people.

When the Yayoi people arrived, they brought wet rice farming to Japan, which would have led to a more stable food supply for the remaining Jomon people living with the new Yayoi migrants.

The lesser amount of archaeological remains from the Late Jomon Period could be evidence of an actual population decline, or just that the archaeological dig sites have not yet been found.

Genetic evidence

Ohashi’s research team decided to start digging through the human genome to address this archaeological mystery. They began by comparing the Y-chromosome sequences of modern Japanese men to those of Korean and other East Asian men. Y chromosomes are passed on from father to son with very little change over generations, so modern Y-chromosome sequences can reliably estimate the Y chromosomes of men thousands of years ago.

Researchers used DNA samples collected before 1990 from 345 men whose families were from the three main islands of Honshu, Shikoku, and Kyushu in Japan.

The research team identified one group of DNA sequences that only Japanese men had. That unique sequence group likely came from the Jomon people. The researchers identified six sequence groups common to both Japanese men and men with other East Asian heritage (Korean, Vietnamese, Chinese), which likely came from the Yayoi people or other ancestors common to Japanese and East Asian people.

DNA confirms archaeology

Researchers built evolutionary family trees using the Y-chromosome sequences and saw a pattern indicative of a population decrease and sudden increase: a remarkable decrease in the number of ancestral Y-chromosome sequences around 2,500 years ago.

Interestingly, modern Japanese men seem to have a greater percentage of Jomon ancestral DNA in their Y chromosomes than the rest of their genomes.

Previous genetic analyses concluded that modern ethnically Japanese people get about 12 percent of their entire genomes from Jomon ancestors and the rest from Yayoi ancestors. Ohashi’s research team calculated that the one group of Jomon sequences they identified accounted for 35.4 percent of the entire Y chromosome, indicating that the specific sequence would have been extremely common in Jomon men.

Since it is easier for a sequence to become common in a small population, this is another indication that the size of the Jomon population decreased during the Late Jomon Period before the arrival of the Yayoi people.

«We hope this method might be useful to confirm other ancient human dynamics not fully explained by archaeology,» said Ohashi.

The findings are published in Scientific Reports.

Source: University of Tokyo [June 20, 2019]



First Australians may have arrived in large groups using complex technologies

New insights into how people first arrived in Australia have been revealed by a group of experts brought together to investigate the continent’s deep history.

First Australians may have arrived in large groups using complex technologies
The emergent picture of regional Pleistocene complexity from genomes, fossils and material culture
[Credit: Corey J. A. Bradshaw et al. 2019]

They used sophisticated modelling to determine not only the likely routes travelled by Aboriginal people tens of thousands of years ago, but also the sizes of groups required for the population to survive in harsh conditions.

The research, published today in two companion papers (one in Scientific Reports and the other in Nature Ecology and Evolution), confirms the theory that people arrived in several large and deliberate migrations by island-hopping to reach New Guinea more than 50,000 years ago.

While many Aboriginal cultures believe people have always been here, others have strong oral histories of ancestral beings arriving from the north.

«We know that Aboriginal people have lived here for more than 50,000 years. This research offers a greater understanding of how migration events took place and further evidence of the marine and navigation capabilities used to make these deliberate journeys,» said Professor Michael Bird, from the Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage (CABAH) and James Cook University.

The team of multidisciplinary researchers from CABAH and the CSRIO set out to establish the most likely route travelled to reach the ancient mega-continent, known as Sahul (New Guinea, Australia and Tasmania joined at times of low sea level).

First Australians may have arrived in large groups using complex technologies
Arrival of First Australians infographic [Credit: Australian Research Council Centre
of Excellence for Australian Biodiversity and Heritage (CABAH)]

«We developed demographic models to determine which island-hopping route ancient people most likely took,» said CABAH’s Professor Corey Bradshaw, from Flinders University.

«A northern route connecting the islands of Mangoli, Buru, and Seram into West Papua New Guinea would probably have been easiest to navigate and survive. This route was easiest when compared to the southern route from Timor that leads to the now-drowned Sahul Shelf in the modern-day Kimberley region.»

The researchers also used complex mathematical modelling — considering factors including fertility, longevity, past climate conditions, and other ecological principles — to calculate the numbers of people required for the population as a whole to survive.

The simulations indicate that at least 1300 people arrived in either a single migration event or smaller, successive waves averaging at least 130 people every 70 years or so, over the course of about 700 years.

«This suggests planned and well-organised maritime migration, rather than accidental arrival» Professor Bradshaw added.

The studies confirm the ancestors of Aboriginal and Torres Strait Islander people possessed sophisticated technology and knowledge to build watercraft. This research also showcases the remarkable ability at that time to plan, navigate, and make multiple complicated, open-ocean voyages to directly transport large numbers of people.

«Both studies are unique because they relied on past environmental information and did not use any genetic data. We are very excited to see how further archaeological and genetics studies in CABAH can contribute to this story,» says Dr Laura Weyrich, a CABAH investigator at the University of Adelaide.

The papers Early human settlement of Sahul was not an accident and Minimum founding populations for the first peopling of Sahul, were co-authored by scientists from around Australia, including Flinders University, James Cook University, University of Wollongong, University of New South Wales, University of Adelaide, Australian National University, and the CSIRO.

CABAH brings together expertise from diverse academic disciplines to answer fundamental questions about the natural and human history of our region, including how and when people first came to Australia.

Source: Flinders University [June 20, 2019]



Sphalerite, Quartz, Lollingite | #Geology #GeologyPage…

Sphalerite, Quartz, Lollingite | #Geology #GeologyPage #Mineral

Locality: Ait Ahmane, Bou Azzer, Ouarzazate Province, Morocco

Size: 3.5 x 2.4 x 2.1 cm

Photo Copyright © Spirifer Minerals

Geology Page



Marine life recovery following the dinosaurs’ extinction…

Marine life recovery following the dinosaurs’ extinction http://www.geologypage.com/2019/06/marine-life-recovery-following-the-dinosaurs-extinction.html

Some of Earth’s oldest animals could take trips…

Some of Earth’s oldest animals could take trips http://www.geologypage.com/2019/06/some-of-earths-oldest-animals-could-take-trips.html

Plate tectonics may have driven ‘Cambrian Explosion’…

Plate tectonics may have driven ‘Cambrian Explosion’ http://www.geologypage.com/2019/06/plate-tectonics-may-have-driven-cambrian-explosion.html

Tumultuous Clouds of Jupiter

NASA — JUNO Mission logo.

June 21, 2019

This stunning compilation image of Jupiter’s stormy northern hemisphere was captured by NASA’s Juno spacecraft as it performed a close pass of the gas giant planet. Some bright-white clouds can be seen popping up to high altitudes on the right side of Jupiter’s disk. (The Juno team frequently refers to clouds like these as «pop-up» clouds in image captions.)

Juno took the four images used to produce this color-enhanced view on May 29, 2019, between 12:52 a.m. PDT (3:52 a.m. EDT) and 1:03 a.m. PDT (4:03 a.m. EDT), as the spacecraft performed its 20th science pass of Jupiter. At the time the images were taken, the spacecraft was between 11,600 miles (18,600 kilometers) and 5,400 miles (8,600 kilometers) above Jupiter’s cloud tops, above a northern latitude spanning from about 59 to 34 degrees.

Juno spacecraft orbiting Jupiter

Citizen scientist Kevin M. Gill created this image using data from the spacecraft’s JunoCam imager.

JunoCam’s raw images are available for the public to peruse and process into image products at

More information about Juno is at https://www.nasa.gov/juno and https://missionjuno.swri.edu.

Image, Animation, Text, Credits: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill.

Greetings, Orbiter.chArchive link

Distant processes influence marine heatwaves around the world

The frequency of marine heatwave days increased by 50% over the past century but our ability to predict them has been limited by a lack of understanding around the key global processes that cause and amplify these events.

Distant processes influence marine heatwaves around the world
A new global assessment of marine heatwaves reveals the drivers and amplifiers of these events
in every ocean basin [Credit: Patrik Linderstam (Unsplash)]

Now, an international team, led by Australian researchers from the ARC Centre of Excellence for Climate Extremes (CLEX) and the Institute for Marine and Antarctic (IMAS) studies, has published in Nature Communications the first global assessment of the major drivers of marine heatwaves.

They found that known climate phenomena, like the El Nino — Southern Oscillation or the North Atlantic Oscillation, with their centre-of-action in one ocean basin can increase the odds of marine heatwaves in other regions thousands of kilometres away.

«Scientific understanding of marine heatwaves is in its infancy but the damage these events do to marine ecosystems, fisheries and tourism can be immense and makes them an important area of study,» said lead author of the study, IMAS Professor Neil Holbrook.

«Given marine heatwaves are increasing in frequency and this trend is expected to continue, our team wanted to set a baseline for our understanding of the physical mechanisms that drive them. Also, we were interested to get a sense of whether the likelihood of marine heatwaves may be increased or decreased based on climatic influences.»

The assessment considered marine heatwaves and their drivers in 22 regions across four ocean and climate zones, based on published papers since 1950.

The team also further examined relationships between marine heatwaves and nine known climate ocscillations/patterns, and whether marine heatwave likelihood might be enhanced or suppressed by these factors. Finally, the team estimated the intensities, duration and extent of the reported marine heatwaves over the satellite observing period since 1982.

The researchers found that marine heatwaves may be influenced by several factors in combination, where processes may be both local and remote to the events.

«The El Nino — Southern Oscillation not only influences marine heatwaves in the Pacific Ocean but also in the Indian Ocean and played a leading role in the extreme marine heatwave known as the Ningaloo Nino in Western Australia in 2011,» said CLEX co-author Dr Alex Sen Gupta.

«We also found that other climate phenomena such as the Indian Ocean Dipole and North Atlantic Oscillation influence marine heatwave probabilities.»

The global assessment also revealed some startling extreme marine heatwave records.

The researchers found the largest area affected by the heatwaves occurred in the northeast Pacific where, in 2015, a marine heatwave covered an area almost twice as large as other previous reports around the globe.

The most intense heatwave they found was in the northwest Atlantic Ocean during 2012, where the temperature peaked at 10.3°C degrees above average for that time of year.

While the records are remarkable, the baseline knowledge from this study regarding the important drivers of marine heatwaves across the globe will be invaluable to researchers.

Source: University of New South Wales [June 17, 2019]



Global commodities trade and consumption place the world’s primates at risk of...

A recent study published in the peer-reviewed journal PeerJ — the Journal of Life and Environmental Sciences highlights the fact that the economic benefits of commodity export for primate habitat countries has been limited relative to the extreme environmental costs of pollution, habitat degradation, loss of biodiversity, continued food insecurity and the threat of emerging diseases.

Global commodities trade and consumption place the world's primates at risk of extinction
Photos of selected primate species impacted by forest loss and degradation resulting
from production of forest-risk commodities [Credit: Estrada et al. 2019]

The world’s primate fauna, distributed in the Neotropics, Africa and in South and Southeast Asia, represents an important global component of the Earth/s land-based biodiversity. The presence and activities of primates support a range of tropical community-wide ecological functions and services that provide vital resources to natural ecosystems, including local human populations.
Alarmingly, around 60% of primate species are now threatened with extinction and ~75% have declining populations as a result of escalating anthropogenic pressures resulting in deforestation, habitat degradation, and increased spatial conflict between an expanding human population and the natural range of primates.

The study finds that growing market demands for food and nonfood commodities from high-income nations and the global community at large are significant drivers of rapid and widespread primate habitat loss and degradation.

Global commodities trade and consumption place the world's primates at risk of extinction
Credit: Estrada et al. 2019

The global consumption of food and natural resources, along with an increasingly globalized economy has created an expanding international market for agricultural products. Such growth is also reflected in the growth of the area of deforestation that is commodity driven. Available evidence indicates that between 2001 to 2015, 160 million hectares of forest were lost in the tropics due to human activities and that 50% or more of this loss was commodity driven. That is, forests were converted to agricultural fields, cattle pastures, mines to extract minerals and metals, fossil fuel exploration, and urbanization.
Given that global commodity resource extraction is predicted to more than double, from 85bn tonnes today to 186bn by the year 2050, reversing the current trend of primate population decline and extinction due to habitat loss and degradation will require a stronger global resolve to reduce the world’s per capita demand for forest-risk food and nonfood commodities from primate-range regions, while at the same time implementing sustainable land use practices that improve the standard of living for local human communities, protect local biodiversity, and mitigate climate change.

Global commodities trade and consumption place the world's primates at risk of extinction
Credit: Estrada et al. 2019

In order to avoid the impending extinction of the world/s primates, the researchers suggest a number of measures to be implemented including changing global consumer habits (e.g., using less oil seed, eating less meat), the creation of an international environmental improvement fund to mitigate the negative effects of forest-risk commodities trade, and assigning responsibility for environmental damage to those international corporations that control production, export, and supply chains.
Authors Alejandro Estrada, Paul A. Garber and Abhishek Chaudhary write, «Growing global consumer demands for food and non-food commodities from primate range regions are placing primate populations at risk of extinction. These increasing demands have resulted in an accelerated global expansion of agriculture and of extractive industries and in the growth of infrastructure to support these activities leading to widespread primate habitat loss and degradation.»

«Primates and their habitats are a vital component of the world’s natural heritage and culture and as our closest living biological relatives, nonhuman primates deserve our full attention, concern, and support for their conservation and survivorship», the authors argue.

Source: PeerJ [June 17, 2019]



Tracking life’s first step: Two molecules ‘awaken’ brand new genome

Within hours after fertilization, a unique genome forms from chromosomes contributed by the egg and sperm. However, this new genome is initially inactive and must be «awakened» to begin the transcription of its DNA and start embryonic development. How life’s first step happens has long fascinated developmental biologists.

Tracking life's first step: Two molecules 'awaken' brand new genome
Credit: Yale University

«This is the beginning of life from a molecular standpoint,» said Antonio Giraldez, the Fergus F. Wallace Professor of Genetics and chair of the Department of Genetics at Yale. «What hasn’t been clear is how and what kick-starts the transcriptional activity of the embryonic genome, so that the embryo starts taking control of its own development with its own genetic blueprint.»
Giraldez and his research team at Yale found that two specific factors are needed to activate DNA in the newly formed genome, they report in the journal Developmental Cell. Using a combination of microscopy and RNA sequencing analysis, they revealed the pattern of transcription within the nucleus of a zebrafish embryo.

The researchers also developed tools to visualize the first activated gene in the zebrafish genome, known as miR-430, and trace the gene’s activity in living embryos.

«Now we can visually look inside the nucleus and analyze how the first gene within the silent genome is awakened,» said Shun Hang Chan lead author of the study and a doctoral student working in the Giraldez lab.
The activation of the zebrafish genome requires the presence of two proteins — P300 and Brd4 — produced by the mother. Disruption of the activity of these two proteins using small molecule inhibitors prevents the activation of the embryonic genome, which in turn blocks development of the embryo. However, researchers found that even after they blocked the production of these maternal proteins, they could overcome this block and prematurely kick-start activation of the embryonic genome through the artificial introduction of P300 and Brd4.

«These molecular factors act as a sort of molecular timer, which sets the timing of genome’s awakening,» Giraldez said. «Finding these key factors involved in genome activation serve as the critical first step towards our understanding of how life begins.»

Author: Bill Hathaway | Source: Yale University [June 17, 2019]



Almond genome reveals how edible, sweet almonds arose

The sweet, edible almonds we enjoy today are a far cry from their bitter wild ancestors thanks to a point mutation in the genes, according to a new study published in the journal Science, which presents the completed almond reference genome.

Almond genome reveals how edible, sweet almonds arose
Penta almond variety [Credit: Federico Dicenta]

It’s thought that the initial domestication of the almond tree occurred in the Near East sometime during the first half of the Holocene, a hypothesis supported by early archaeological evidence of the nut in both ancient Egypt and Greece.

Wild almond species accumulate the bitter and toxic cyanogenic glycoside amygdalin, and research has suggested that initial domestication of the almond was enabled by the selection of sweet, edible kernel genotypes, which originated within the inedible wild genotypes.

Since its initial domestication, the almond has become one of the most widespread tree nut species on Earth. Despite the distribution and economic importance of the almond, however, a detailed understanding of the plant’s genome has lagged behind that other species in the Rosaceae family of plants, and the nature of the gene that allowed for edible, sweet kernel nuts has remained elusive.

Here, Raquel Sanchez-Perez and colleagues present the completed reference genome of the almond (Prunus amygdalus). What’s more, the authors used the assembled sequence to reveal the genetic differences between toxic, bitter almonds and their sweet counterparts.

The authors discovered a cluster of transcription factors associated with sweet kernel genotypes. Among these, bHLH2 was revealed to be involved with the regulation of the biosynthetic pathway for the production of the toxic compound amygdalin.

According to the results, a mutation in bHLH2 prevents amygdalin production, resulting in the sweet almond genotype, which was actively selected for during domestication.

Source: American Association for the Advancement of Science [June 17, 2019]



3D reconstruction of craniums elucidates the evolution of New World monkeys

Cranial fossils belonging to two extinct species of monkey — Caipora bambuiorum and Cartelles coimbrafilhoi — were examined by computed tomography (CT) scan and reconstructed with three-dimensional imaging by a group of scientists from various countries.

3D reconstruction of craniums elucidates the evolution of New World monkeys
Computed tomography scans of fossils from two extinct species point to evolutionary adaptations and kinship
with extant howler, spider and woolly monkeys [Credit: Andre Menezes Strauss]

The fossils were found almost 30 years ago in a cave complex in Bahia, Brazil, located in the Caatinga, a semiarid biome that occupies part of Brazil’s Northeast Region.

The images were compared with those of craniums from 14 extant Central and South American primate species, enabling the researchers to identify adaptations and infer previously unknown relationships between the extinct and extant species.

«This is the first ever study of endocranial morphology involving fossils of New World monkeys, or platyrrhines,» said Andre Menezes Strauss, a professor at the University of Sao Paulo’s Archeology and Ethnology Museum (MAE) and an associate researcher affiliated with the Laboratory of Archeology and Environmental/Evolutionary Anthropology (LAAAE) at the university’s Institute of Biosciences (IB-USP) in Brazil.

Using a cast taken from the inside of the cranium (braincase), paleoanthropologists analyzed endocranial morphology to estimate the shape and size of the brains of the fossil primates.

The results of the study, which was supported by Sao Paulo Research Foundation — FAPESP, are published in the American Journal of Physical Anthropology.

The researchers described cranial and endocranial shape variations in 14 species belonging to the four extant genera in the family Atelidae — Alouatta (howler monkeys), Ateles (spider monkeys), Brachyteles (woolly spider monkeys or muriquis), and Lagothrix(woolly monkeys) — as well as the extinct species C. bambuiorum and C. coimbrafilhoi. There are approximately 350 primate species in the world today. More than 200 are platyrrhines.

The study was led by Ivan Perez, an anthropologist at Argentina’s La Plata Museum. His collaborators included Brazilian scientists affiliated with the University of Sao Paulo (USP) and the University of Campinas (UNICAMP), as well as researchers at institutions in Belgium, France, Germany and the United States. Castor Cartelle, a paleontologist at the Pontifical Catholic University of Minas Gerais state (PUC-MG) for whom Cartelles coimbrafilhoi is named, was also a member of the research team.

In addition to FAPESP, Brazil’s National Council for Scientific and Technological Development (CNPq) and Argentina’s Scientific and Technological Research Fund (FONCYT) and National Scientific and Technical Research Council (CONICET) also supported the study.

The fossil specimens of C. bambuiorum and C. coimbrafilhoi are deposited at PUC-MG’s Natural History Museum in Belo Horizonte, Minas Gerais. The 14 crania of the extant platyrrhines came from collections held by Argentina’s La Plata Museum, Brazil’s National Museum in Rio de Janeiro, the Argentinian Natural Science Museum in Buenos Aires, and the US National Museum of Natural History in Washington, DC.

«All 16 specimens were digitized using a medical CT scanner. A virtual 3D model of the endocranium was generated for each sample, and the 3D models of the cranial surfaces were extracted from the CT scan data,» Strauss told.

The fossil specimens were damaged, particularly in the region of the zygomatic arches (cheekbones), so the researchers opted for two strategies to analyze them. According to Strauss, in the case of C. bambuiorum, the right zygomatic arch was absent, but the left arch was intact.

«We reflected the undamaged arch to the damaged side in the 3D model, taking advantage of bilateral symmetry, and by means of this virtual repair, obtained a complete specimen,» he said.

«In C. coimbrafilhoi, both sides were absent, so we used an imputation method to estimate the positions of the missing parts.»

Perez digitized 26 anatomical landmarks and 373 semilandmarks along the curves and surfaces of each endocranium, as well as 64 landmarks and 196 semilandmarks on each cranium. In geometrical morphometrics, a landmark is a 2D or 3D point of evolutionary significance. Semilandmarks are defined by locations relative to other landmarks, e.g., midway between landmarks X and Y.

«The data served as a basis for multivariate analysis to compare all the characteristics of the 16 specimens and to look for similarities and differences that indicated morphological [and hence] adaptive patterns,» Strauss said.

In other words, because the specimens of extant species of Atelidae, the largest New World monkeys, included crania of Alouatta, Ateles, Brachyteles and Lagothrix, they were compared with the specimens of the extinct species in order to find out whether the two fossils resembled and might be closely related to any of them.

Strauss said the data clearly showed that C. bambuiorum should be grouped with Ateles, Brachyteles and Lagothrix, all of which are distant from Alouatta.

3D reconstruction of craniums elucidates the evolution of New World monkeys
Computed tomography scans of fossils from two extinct species point to evolutionary adaptations and kinship
with extant howler, spider and woolly monkeys [Credit: Andre Menezes Strauss]

This means that the genus Alouatta shares a common ancestor with the other genera of Atelidae and with C. bambuiorum and that it is older than the common ancestor shared by Ateles, Brachyteles and Lagothrix.

«However, when the position of C. bambuiorum is analyzed solely in relation to Ateles, Brachyteles and Lagothrix, the conclusion is that the fossil is clearly closest to Brachyteles,» Strauss said.

«The hypothesis that C. bambuiorum was similar to a giant spider monkey (Ateles), initially posited by Castor Cartelle 20 years ago, was refuted by our data, which showed that the extinct monkey was actually much more similar to a ‘giant’ muriqui (Brachyteles).»

In the case of C. coimbrafilhoi, the multivariate analysis produced some surprises. The first was that the data did not clearly group it with any of the four extant genera of Atelidae but consistently filled the previously empty morphospace between Alouatta and the other three genera.

«With regard to the fossil species, we show that C. bambuiorum is positioned within the range of variation observed for Brachyteles, whereas C. coimbrafilhoi presents an endocranial shape that does not overlap with the range of variation observed for any of the extant Atelidae. Of the four genera, C. coimbrafilhoi is closest to Alouatta in endocranial morphospace but closest to Lagothrix in cranial terms,» Strauss said.

«We found that when the size factor was removed, the characteristics of C. coimbrafilhoi were intermediate between Alouatta on one side, and Ateles, Brachyteles and Lagothrix on the other,» Strauss said.

«Our results suggest that within the atelid clade, the extinction of C. bambuiorum and C. coimbrafilhoi led to a significant loss of biological variation that could not have been imagined with the discovery of these fossils,» the article concludes.

The entire lineage of New World primates, distributed from northern Argentina to Central America, the Caribbean and Mexico, descends from a single band of founders comprising small African monkeys believed to have crossed the former South Atlantic (then a third of its current size) some 45 million years ago on rafts of floating vegetation.

Research on monkey fossils in the Americas began in Brazil 183 years ago in 1836, when Danish naturalist Peter Wilhelm Lund discovered the remains of a much larger primate than all extant platyrrhines in a cave in the Lagoa Santa area of Minas Gerais.

Lund named this monkey Protopithecus brasiliensis, which means «Brazilian ancestral monkey». It became extinct over 10,000 years ago and is a close relative of Brachyteles, the largest extant platyrrhine.

Fossils found since then (mostly single teeth and fragments of mandibles, plus a few craniums) belonged to very ancient platyrrhines that became extinct millions or tens of millions of years ago in Argentinian Patagonia, high up in the Chilean Andes and Bolivian Altiplano, in the Amazon rainforest of Peru, and on several Caribbean islands.

Although more than 30 extinct platyrrhine species have now been described, P. brasiliensis has never lost its status as a giant much larger than the rest, with two exceptions.

Almost complete skeletons of two other giant platyrrhines were found in 1992 in an inner chamber of Toca da Boa Vista, Brazil’s largest cave complex (in Bahia). They lived at the end of the Ice Age over 10,000 years ago.

Both fossils were studied at PUC-MG by Cartelle, who described one of the specimens as a giant spider monkey belonging to a new species he called Caipora bambuiorum. He identified the second specimen as a member of the species described by Lund (P. brasiliensis).

C. bambuiorum and P. brasiliensis belong to the family Atelidae. The largest atelid genus is Brachyteles, whose members can reach 15 kg, followed by Alouatta, which are typically 10 kg or less. C. bambuiorum and P. brasiliensis were 60% larger. When alive, they must have weighed over 25 kg, about as much as an African baboon.

In 2013, thanks to American anthropologists, the fossil found in Toca da Boa Vista and initially thought to be a Protopithecus was found to be an exemplar of a new species named Cartelles coimbrafilhoi in homage to Castor Cartelle.

The research group led by Perez concluded that C. coimbrafilhoi is related to Alouatta and not, as Cartelle thought, to Brachyteles.

New scientific techniques have now supplied a novel interpretation of these two fossils, especially C. coimbrafilhoi.

The 3D model of C. coimbrafilhoi’s cranium constructed by the researchers showed that its morphological adaptations were different from those of any other New World primate, extant or extinct.

«Computed tomography enabled us to produce a new analysis of C. coimbrafilhoi, with novel conclusions. We now believe this giant monkey from the Pleistocene found in Bahia was neither Alouatta nor Brachyteles. Its unique cranial characteristics are no longer seen in any other New World primate,» Strauss said.

The Protopithecus described by Lund was not included the study by Perez, Aristide, Strauss and colleagues, for lack of a cranium that could be scanned. The fossils found so far are highly fragmented.

Author: Peter Moon | Source: FAPESP [June 17, 2019]



ALMA finds earliest example of merging galaxies

Researchers using ALMA (Atacama Large Millimeter/submillimeter Array) observed signals of oxygen, carbon, and dust from a galaxy in the early Universe 13 billion years ago. This is the earliest galaxy where this useful combination of three signals has been detected. By comparing the different signals, the team determined that the galaxy is actually two galaxies merging together, making it the earliest example of merging galaxies yet discovered.

ALMA finds earliest example of merging galaxies
Artist’s impression of the merging galaxies B14-65666 located 13 billion light years-away
[Credit: National Astronomical Observatory of Japan]

Takuya Hashimoto, a postdoctoral researcher at the Japan Society for the Promotion of Science and Waseda University, and his team used ALMA to observe B14-65666, an object located 13 billion light-years away in the constellation Sextans. Because of the finite speed of light, the signals we receive from B14-65666 today had to travel for 13 billion years to reach us. In other words they show us the image of what the galaxy looked like 13 billion years ago, less than 1 billion years after the Big Bang.
ALMA detected radio emissions from oxygen, carbon, and dust in B14-65666. This is the earliest galaxy where all three of these signals have been detected. The detection of multiple signals is important because they carry complementary information.

Data analysis showed that the emissions are divided into two blobs. Previous observations with the Hubble Space Telescope (HST) had revealed two star clusters in B14-65666. Now with the three emission signals detected by ALMA, the team was able to show that the two blobs do in-fact form a single system, but they have different speeds. This indicates that the blobs are two galaxies in the process of merging. This is the earliest known example of merging galaxies. The research team estimated that the total stellar mass of B14-65666 is less than 10% that of the Milky Way. This means that B14-65666 is in the earliest phases of its evolution. Despite its youth, B14-65666 is producing stars 100 times more actively than the Milky Way. Such active star-formation is another important signature of galactic mergers, because the gas compression in colliding galaxies naturally leads to bursty star-formation.

ALMA finds earliest example of merging galaxies
Composite image of B14-65666 showing the distributions of dust (red), oxygen (green), and carbon (blue),
observed by ALMA and stars (white) observed by the Hubble Space Telescope
[Credit: ALMA (ESO/NAOJ/NRAO), NASA/ESA Hubble Space Telescope,
Hashimoto et al. 2019]

«With rich data from ALMA and HST, combined with advanced data analysis, we could put the pieces together to show that B14-65666 is a pair of merging galaxies in the earliest era of the Universe,» explains Hashimoto. «Detection of radio waves from three components in such a distant object clearly demonstrates ALMA’s high capability to investigate the distant Universe.»
Modern galaxies like our Milky Way have experienced countless, often violent, mergers. Sometimes a larger galaxy swallowed a smaller one. In rare cases, galaxies with similar sizes merged to form a new, larger galaxy. Mergers are essential for galaxy evolution, so many astronomers are eager to trace back the history of mergers.

«Our next step is to search for nitrogen, another major chemical element, and even the carbon monoxide molecule,» said Akio Inoue, a professor at Waseda University. «Ultimately, we hope to observationally understand the circulation and accumulation of elements and material in the context of galaxy formation and evolution.»

These observation results were published in the Publications of the Astronomical Society of Japan.

Source: ALMA [June 18, 2019]



2019 June 21 Sunset Analemma Image Credit & Copyright: …

2019 June 21

Sunset Analemma
Image Credit & Copyright: Marcella Giulia Pace

Explanation: Today, the solstice is at 15:54 Universal Time, the Sun reaching the northernmost declination in its yearly journey through planet Earth’s sky. A June solstice marks the astronomical beginning of summer in the northern hemisphere and winter in the south. It also brings the north’s longest day, the longest period between sunrise and sunset. In fact the June solstice sun is near the top, at the most northern point in the analemma or figure 8 curve traced by the position of the Sun in this composite photo. The analemma was created (video) from images taken every 10 days at the same time from June 21, 2018 and June 7, 2019. The time was chosen to be the year’s earliest sunset near the December solstice, so the analemma’s lowest point just kisses the unobstructed sea horizon at the left. Sunsets arranged along the horizon toward the right (north) are centered on the sunset at the September equinox and end with sunset at the June solstice.

∞ Source: apod.nasa.gov/apod/ap190621.html

Meteor Activity Outlook for June 22-28, 2019

AMS Event #2127-219 captured by Hermann K. from Seppenröth, Austria – May 10th, 2019 © Hermann K. from www.astromethyst.at

During this period the moon reaches its last quarter phase on Tuesday June 25th. At this time the moon is located 90 degrees west of the sun and rises between 0100 and 0200 local daylight saving time (LDST). As the week progresses, the waning crescent moon will rise later in the morning with each passing night, allowing more of the night to be free of interfering moonlight. The estimated total hourly meteor rates for evening observers this week is near 3 for those viewing from the northern hemisphere and 4 for those located south of the equator. For morning observers the estimated total hourly rates should be near 6 as seen from mid-northern latitudes (45N) and 10 as seen from tropical southern locations (25S). The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity. Evening rates are reduced by moonlight during this period. Note that the hourly rates listed below are estimates as viewed from dark sky sites away from urban light sources. Observers viewing from urban areas will see less activity as only the brightest meteors will be visible from such locations.

The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning June 22/23. These positions do not change greatly day to day so the listed coordinates may be used during this entire period. Most star atlases (available at science stores and planetariums) will provide maps with grid lines of the celestial coordinates so that you may find out exactly where these positions are located in the sky. A planisphere or computer planetarium program is also useful in showing the sky at any time of night on any date of the year. Activity from each radiant is best seen when it is positioned highest in the sky, either due north or south along the meridian, depending on your latitude. It must be remembered that meteor activity is rarely seen at the radiant position. Rather they shoot outwards from the radiant so it is best to center your field of view so that the radiant lies at the edge and not the center. Viewing there will allow you to easily trace the path of each meteor back to the radiant (if it is a shower member) or in another direction if it is a sporadic. Meteor activity is not seen from radiants that are located below the horizon. The positions below are listed in a west to east manner in order of right ascension (celestial longitude). The positions listed first are located further west therefore are accessible earlier in the night while those listed further down the list rise later in the night.

Radiant Positions at 22:00 LDST

Radiant Positions at 22:00 Local Daylight Saving Time

Radiant Positions at 01:00 LDST

Radiant Positions at 1:00 Local Daylight Saving Time

Radiant Positions at 04:00 DLST

Radiant Positions at 4:00 Local Daylight Saving Time

These sources of meteoric activity are expected to be active this week.

The June Bootids (JBO) are usually a very weak shower that occasionally produces outbursts. Nothing out of the ordinary is expected this year. These meteors are best seen from June 23-25 with maximum activity occurring on the 24th. At maximum the radiant is located at 14:58 (224) +48. This position lies in northwestern Bootes, 15 degrees east of the second magnitude star known as Alkaid (Eta Ursae Majoris). This radiant is best placed in the evening sky just as the sky becomes dark. Observers in the northern hemisphere have a distinct advantage over those located south of the equator as the radiant lies much higher in the evening sky. No matter your location, little activity is expected from this source. With an entry velocity of 18 km/sec., the average June Bootid meteor would be of very slow velocity.

The center of the large Anthelion (ANT) radiant is currently located at 18:56 (284) -23. This position lies in central Sagittarius, 4 degrees north of the 2nd magnitude star known as Nunki (sigma Sagittarii). Due to the large size of this radiant, anthelion activity may also appear from southeastern Ophiuchus and Scutum as well as Sagittarius. Rates at this time should be near 2 per hour as seen from mid-northern latitudes (45 N) and 3 per hour as seen from the southern tropics (S 25). With an entry velocity of 30 km/sec., the average anthelion meteor would be of slow velocity.

The Northern June Aquilids (NZC) are active from a radiant located at 20:00 (300) -08. This area of the sky is located in southern Aquila, 7 degrees northwest of the 3rd magnitude star known as Algiedi Prima (alpha1 Capricorni). This radiant is best placed near 0200 LST, when it lies on the meridian and is located highest in the sky. Hourly rates at this time should be near 1 no matter your location. With an entry velocity of 38 km/sec., the average meteor from this source would be of medium-slow velocity. An interesting fact about this source is that it may be related to the Northern delta Aquariids of August. Where and when this source ends coincides with the start and position of the Northern delta Aquariids.

The Southern June Aquilids (SZC) were discovered by G. Gartrell and W. G. Elford, in their study of Southern Hemisphere meteor streams. This stream is active from June 9 through July 17 with maximum activity occurring on July 6. The radiant is currently located at 20:22 (306) -32. This area of the sky is actually located in southeastern Sagittarius, 5 degrees northeast of the 4th magnitude star known as Theta1 Sagittarii. This radiant is best placed near 0400 LDST, when it lies on the meridian and is located highest in the sky. Hourly rates at this time will be less than 1 no matter your location. With an entry velocity of 39 km/sec., the average meteor from this source would be of medium-slow velocity.

The beta Equulids (BEQ) were discovered by Dr. Peter Brown and associates using data from the Canadian Meteor Orbit Radar (CMOR) installation. These meteors are active from June 7-30 with maximum activity occurring on June 15th. The radiant position currently lies at 20:37 (309) +02. This area of the sky lies in eastern Aquila, 3 degrees north of the dim star known as 71 Aquilae. These meteors are best seen near during the last dark hour of the night when the radiant lies highest in a dark sky. Hourly rates are expected to be less than 1, no matter your location. With an entry velocity of 33 km/sec., a majority of these meteors will appear to move with medium-slow velocities.

The phi Piscids (PPS) are another discovery by Dr. Peter Brown and associates using data from the Canadian Meteor Orbit Radar (CMOR) installation. These meteors are active from June 8-August 02 with maximum activity occurring on July 5th. The radiant position currently lies at 00:26 (007) +20. This area of the sky lies in north-central Pisces, 5 degrees northeast of the 3rd magnitude star known as Algenib (gamma Pegasi). These meteors are best seen near during the last dark hour of the night when the radiant lies highest in a dark sky. Current rates should be near 1 per hour as seen from the northern hemisphere and less than 1 as seen from south of the equator. With an entry velocity of 67 kilometers per second, a majority of these meteors will appear to move with swift velocities.

The first of the c-Andromedids (CAN) should be seen this week. This stream was discovered by Sirko Molau and Juergen Rendtel using video data from the IMO network. Activity from this source is seen from June 26 through July 27 with maximum activity occurring on July 9. The radiant currently lies at 00:42 (011) +42, which places it in northern Andromeda, almost in contact with the naked eye Andromeda Galaxy. This area of the sky is best seen during the last dark hour before dawn when the radiant lies highest in a dark sky. Observers in the northern hemisphere are better situated to view this activity as the radiant rises much higher in the sky before dawn compared to southern latitudes. Current rates would be less than 1 per hour no matter your location. With an entry velocity of 58 km/sec., the average meteor from this source would be of swift velocity.

The last of the Daytime Arietids (ARI) are expected this weekend. These meteors are difficult to catch as the radiant only lies 30 degrees west of the sun. Therefore the only time these meteors are visible is during the last dark hour before dawn. The radiant is currently located at 03:51 (058) +27. This area of the sky is located in western Taurus, 3 degrees north of the naked eye star cluster known as the Pleiades. Current rates are expected to be less than 1 no matter your location. With an entry velocity of 41 km/sec., the average meteor from this source would be of medium velocity.

As seen from mid-northern hemisphere (45N), morning rates would be near 6 per hour as seen from rural observing sites and 1 per hour during the evening hours. As seen from the tropical southern latitudes (25S), one would expect to see approximately 11 sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near 3 per hour. Locations between these two extremes would see activity between the listed figures. Evening rates are reduced during this period due to bright moonlight.

The list below offers the information from above in tabular form. Rates and positions are exact for Saturday night/Sunday morning except where noted in the shower descriptions.

RA (RA in Deg.) DEC Km/Sec Local Daylight Saving Time North-South
June Bootids (JBO) Jun 24 14:58 (224) +48 18 23:00 <1 – <1 III
Anthelion (ANT) 18:56 (284)  -23 30 02:00 2 – 3 II
Northern June Aquilids (NZC) Jul 03 20:00 (300) -08 41 03:00 1 – 1 IV
Southern June Aquilids (SZC) Jul 06 20:22 (306) -32 39 03:00 <1 – <1 IV
beta Equulids (BEQ Jun 15 20:37 (309) +02 33 04:00 <1 – <1 IV
phi Piscids (PPS) Jul 05 00:26 (007) +20 67 08:00 1 – <1 IV
c-Andromedids (CAN) Jul 09 00:42 (011) +42 58 08:00 <1 – <1 IV
Daytime Arietids (ARI) Jun 08 03:51 (058) +27 41 11:00 <1 – <1 II

Source link


    Солнечное затмение 14 декабря 2020 года  — полное  солнечное затмение  142  сароса , которое лучше всего будет видно в юго-восточной час...