Brilliant iron molecule could provide cheaper solar energy

The new molecule.

For the first time, researchers have succeeded in creating an iron molecule that can function both as a photocatalyst to produce fuel and in solar cells to produce electricity. The results indicate that the iron molecule could replace the more expensive and rarer metals used today.

Some photocatalysts and solar cells are based on a technology that involves molecules containing metals, known as metal complexes. The task of the metal complexes in this context is to absorb solar rays and utilise their energy. The metals in these molecules pose a major problem, however, as they are rare and expensive metals, such as the noble metals ruthenium, osmium and iridium.

"Our results now show that by using advanced molecule design, it is possible to replace the rare metals with iron, which is common in the Earth's crust and therefore cheap," says Chemistry Professor Kenneth Wärnmark of Lund University in Sweden.

Together with colleagues, Kenneth Wärnmark has for a long time worked to find alternatives to the expensive metals. The researchers focused on iron which, with its six per cent prevalence in the Earth's crust, is significantly easier to source. The researchers have produced their own iron-based molecules whose potential for use in solar energy applications has been proven in previous studies.

In this new study, the researchers have moved one step further and developed a new iron-based molecule with the ability to capture and utilise the energy of solar light for a sufficiently long time for it to react with another molecule. The new iron molecule also has the ability to glow long enough to enable researchers to see iron-based light with the naked eye at room temperature for the first time.

"The good result depends on the fact that we have optimised the molecular structure around the iron atom," explains colleague Petter Persson of Lund University.

The study is now published in the journal Science. According to the researchers, the iron molecule in question could be used in new types of photocatalysts for the production of solar fuel, either as hydrogen through water splitting or as methanol from carbon dioxide. Furthermore, the new findings open up other potential areas of application for iron molecules, e.g. as materials in light diodes (LEDs).

What surprised the Lund researchers is that they arrived at good results so quickly. In just over five years, they succeeded in making iron interesting for photochemical applications, with properties largely as good as those of the best noble metals.

"We believed it would take at least ten years," says Kenneth Wärnmark.

Read more at Science Daily

Is being a night owl bad for your health?

Night owls may have a higher risk of suffering from heart disease and type 2 diabetes than early risers.

In the first ever international review of studies analysing whether being an early riser or a night owl can influence your health, researchers have uncovered a growing body of evidence indicating an increased risk of ill health in people with an evening preference as they have more erratic eating patterns and consume more unhealthy foods.

The findings have been reported in Advances in Nutrition today (Friday 30 November)

The human body runs on a 24-hour cycle which is regulated by our internal clock, which is known as a circadian rhythm, or chronotype. This internal clock regulates many physical functions, such as telling you when to eat, sleep and wake. An individual's chronotype leads to people having a natural preference towards waking early or going to bed late.

The researchers found increasing evidence emerging from studies linking conditions such as heart disease and type 2 diabetes to people with the evening chronotype -- a natural preference for evenings.

People who go to bed later tend to have unhealthier diets, consuming more alcohol, sugars, caffeinated drinks and fast food than early risers. They consistently report more erratic eating patterns as they miss breakfast and eat later in the day. Their diet contains less grains, rye and vegetables and they eat fewer, but larger, meals. They also report higher levels of consumption of caffeinated beverages, sugar and snacks, than those with a morning preference, who eat slightly more fruit and vegetables per day. This potentially explains why night owls have a higher risk of suffering from chronic disease.

Eating late in the day was also found to be linked to an increased risk of type 2 diabetes because the circadian rhythm influences the way glucose is metabolised in in the body.

Glucose levels should naturally decline throughout the day and reach their lowest point at night. However, as night owls often eat shortly before bed, their glucose levels are increased when they are about to sleep. This could negatively affect metabolism as their body isn't following its normal biological process.

One study showed that people with an evening preference were 2.5 times more likely to have type 2 diabetes than those with a morning preference.

This also impacts on people who work shifts -- particularly rotating shifts -- as they are constantly adjusting their body clock to fit with their working hours. The researchers found that this reduces their sensitivity to insulin and affects their glucose tolerance, putting them at greater risk of developing type 2 diabetes.

The review also uncovered interesting trends:

• People's preferences to rising early and going to bed later change at varying points in the life cycle. The morning chronotype is more common in children and can appear when a baby is just three-weeks old. This changes during childhood. While over 90% of two-year-olds have a morning preference, this declines to 58% by the age of six, and shifts further towards an evening preference during puberty. This evening preference continues until an adult reaches their early 50's and they then begin to revert back to a morning preference.
• Ethnicity and society can also influence your chronotype. For example, studies have revealed that Germans are more likely to have an evening preference in comparison to Indians and Slovakians. There can also be differences between people living in urban and rural areas in the same country.
• Another study noted that being exposed to daylight influenced sleep. Every additional hour spent outdoors was associated with 30 minutes of 'advance sleep' and that the noise, ambient lighting and crowding of urban environments can make people in some areas more likely to have a morning or evening preference.
• The researchers also found evidence that night owls would accumulate 'sleep debt' during the working week and would sleep longer at weekends to compensate for this, whereas early birds had smaller differences in their sleeping patterns across the week.

The study was led by Dr Suzana Almoosawi from Northumbria University, Newcastle in the UK and Dr Leonidas Karagounis, Nestle Health Science in Switzerland with academics representing Nestle Research (Switzerland) the University of Surrey (UK), Orebro University (Sweden), the National University of Singapore, the London School of Hygiene and Tropical Medicine, Ecole Polytechnique Federale de Lausanne (Switzerland) and Plymouth Marjon University (UK).

Dr Almoosawi, a Research Fellow in Northumbria's Brain, Performance and Nutrition Research Centre, explained: "We have found that your genes, ethnicity and gender determine the likelihood of you being a morning or evening type. In adulthood, being an evening chronotype is associated with greater risk of heart disease and type 2 diabetes, and this may be potentially due to the poorer eating behaviour and diet of people with evening chronotype. Our review also found that people who have a poorer control of their diabetes are more likely to be evening types.

"The review has highlighted a major gap in our understanding as to how our biological clock affects food intake in infants, children and the elderly. While most infants synchronise their body clock to that of their mothers, as they reach six-years of age, we observe that a large proportion begin to show signs of developing an evening chronotype. Whether physiological changes, school timings or social schedules determine this change, we do not know.

Dr Almoosawi added: "In teenagers, we also find that evening chronotype is related to more erratic eating behaviour and poorer diet. This could have important implications to health in adulthood as most dietary habits are established in adolescence."

The review team have called for more studies in the general population that define people's body clock and how this relates in the long-term to their dietary habits and health.

Dr Leonidas G Karagounis of Nestle Health Science, said: "Scientific evidence is providing increasing insight into the relationship between your chronotype, diet and cardiometabolic health. Overall, cross-sectional studies suggest that an evening chronotype is associated with lower intake of fruits and vegetables, and higher intake of energy drinks, alcoholic, sugary and caffeinated beverages, as well as higher energy intake from fat.

Read more at Science Daily

The whole of Africa was the cradle of humankind

Members of Ain Hanech team excavating at Ain Boucherit.

A team of scientists led by Mohamed Sahnouni, archaeologist at the Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), has just published a paper in the journal Science which breaks with the paradigm that the cradle of Humankind lies in East Africa, based on the archaeological remains found at sites in the region of Ain Hanech (Algeria), the oldest currently known in the north of Africa.

For a long time, East Africa has been considered the place of origin of the earliest hominins and lithic technology, because up to now, very little was known about the first hominin occupation and activities in the north of the continent. Two decades of field and laboratory research directed by Dr. Sahnouni have shown that ancestral hominins actually made stone tools in North Africa that are near contemporary with the earliest known stone tools in East Africa dated to 2.6 million years.

These are stone artifacts and animal bones bearing marks of cutting by stone tools, with an estimated chronology of 2.4 and 1.9 million years, respectively, found at two levels at the sites of Ain Boucherit (within the Ain Hanech study area), which were dated using Paleomagnetism, Electron Spin Resonance (ESR), and the Biochronology of large mammals excavated together with the archaeological materials.

Fossils of animals such as pigs, horses and elephants, from very ancient sites, have been used by the paleontologist Jan van der Made, of the Museo Nacional de Ciencias Naturales in Madrid, to corroborate the ages yielded by Paleomagnetism, obtained by the CENIEH geochronologist Josep Parés, and ESR, found by Mathieu Duval, of Griffith University.

Oldowan technology

The artifacts of Ain Boucherit were manufactured of locally available limestone and flint and include faces worked into choppers, polyhedra and subspheroids, as well as sharp-edged cutting tools used to process animal carcasses. These artifacts are typical of the Oldowan stone technology known from 2.6-1.9 million-year-old sites in East Africa, although those from Ain Boucherit show subtle variations.

"The lithic industry of Ain Boucherit, which is technologically similar to that of Gona and Olduvai, shows that our ancestors ventured into all corners of Africa, not just East Africa. The evidence from Algeria changes the earlier view that East Africa was the cradle of Humankind. Actually, the whole of Africa was the cradle of humankind," states Sahnouni, leader of the Ain Hanech project.

Not mere scavengers

Ain Boucherit is one of the few archaeological sites in Africa which has provided evidence of bones with associated marks of cutting and percussion in situ with stone tools, which shows unmistakably that these ancestral hominins exploited meat and marrow from animals of all sizes and skeletal parts, which implied skinning, evisceration and defleshing of upper and intermediate extremities.

Isabel Cáceres, taphonomist at the IPHES, has commented that "the effective use of sharp-edged tools at Ain Boucherit suggests that our ancestors were not mere scavengers. It is not clear at this moment whether they hunted, but the evidence clearly shows that they were successfully competing with carnivores and enjoyed first access to animal carcasses."

The tool-makers

At this moment, the most important question is who made the stone tools discovered in Algeria. Hominin remains have still not been found in North Africa which are contemporary with the earliest stone artifacts. As a matter of fact, nor have any hominins yet been documented in direct association with the first stone tools known from East Africa.

Nevertheless, a recent discovery in Ethiopia has shown the presence of early Homo dated to 2.8 million years, most likely the best candidate also for the materials from East and North Africa.

Scientists thought for a long time that the hominins and their material culture originated in the Great Rift Valley in East Africa. Surprisingly, the earliest known hominin, dated to 7.0 million years, and the 3.3 million years Australopithecus bahrelghazali, have been discovered in Chad, in the Sahara, 3000 km from the rift valleys in the east of Africa.

As Sileshi Semaw, scientist at the CENIEH and a co-author of this paper, explains that the hominins contemporary with Lucy (3.2 million years), were probably roamed over the Sahara, and their descendants might have been responsible for leaving these archaeological puzzles now discovered in Algeria, that are near contemporaries of those of East Africa.

Read more at Science Daily

Black hole 'donuts' are actually 'fountains'

The three gaseous components form the long-theorized 'donut' structure: (1) a disk of infalling dense cold molecular gas, (2) outflowing hot atomic gas, and (3) gas returning to the disk.

Based on computer simulations and new observations from the Atacama Large Millimeter/submillimeter Array (ALMA), researchers have found that the rings of gas surrounding active supermassive black holes are not simple donut shapes. Instead, gas expelled from the center interacts with infalling gas to create a dynamic circulation pattern, similar to a water fountain in a city park.

Most galaxies host a supermassive black hole, millions or billions of times as heavy as the Sun, in their centers. Some of these black holes swallow material quite actively. But astronomers have believed that rather than falling directly into the black hole, matter instead builds up around the active black hole forming a donut structure.

Takuma Izumi, a researcher at the National Astronomical Observatory of Japan (NAOJ), led a team of astronomers that used ALMA to observe the supermassive black hole in the Circinus Galaxy located 14 million light-years away from the Earth in the direction of the constellation Circinus. The team then compared their observations to a computer simulation of gas falling towards a black hole made with the Cray XC30 ATERUI supercomputer operated by NAOJ. This comparison revealed that the presumptive "donut" is not actually a rigid structure, but instead a complex collection of highly dynamic gaseous components. First, cold molecular gas falling towards the black hole forms a disk near the plane of rotation. As it approaches the black hole, this gas is heated until the molecules break down into the component atoms and ions. Some of these atoms are then expelled above and below the disk, rather than being absorbed by the black hole. This hot atomic gas falls back onto the disk creating a turbulent three dimensional structure. These three components circulate continuously, similar to a water fountain in a city park.

"Previous theoretical models set a priori assumptions of rigid donuts," explains Keiichi Wada, a theoretician at Kagoshima University in Japan, who lead the simulation study and is a member of the research team. "Rather than starting from assumptions, our simulation started from the physical equations and showed for the first time that the gas circulation naturally forms a donut. Our simulation can also explain various observational features of the system."

"By investigating the motion and distribution of both the cold molecular gas and warm atomic gas with ALMA, we demonstrated the origin of the so-called 'donut' structure around active black holes," said Izumi. "Based on this discovery, we need to rewrite the astronomy textbooks."

From Science Daily

Fires fueled spread of grasslands on ancient Earth

Outcrops in Pakistan provided paleosol, or fossil soil samples, used to test the role of fire in the spread of grasslands nearly 10 million years ago.

Ancient wildfires played a crucial role in the formation and spread of grasslands like those that now cover large parts of the Earth, according to scientists at Penn State and the Smithsonian National Museum of Natural History.

A new study links a large rise in wildfires nearly 10 million years ago, in the late Miocene, with a major shift in vegetation on land, as indicated by carbon isotopes of plant biomarkers found in the fossil record. Frequent, seasonal fires helped turn forested areas into open landscapes, and drove the expansion of grasslands, the researchers said.

The team developed an innovative approach to test the role of fire in the rise of early grasslands. They analyzed tracers of ancient leaves and of burned organic matter left behind in paleosols, or fossil soils, in northern Pakistan.

"The tools we use are molecules and biomarkers produced by organisms in Earth history and preserved in rocks," said Allison Karp, a graduate student in geosciences at Penn State and lead author on the paper. "We can use these as clues to figure out what was happening with climate and ecology in the past."

The new technique has broad implications as a tool for scientists seeking to answer questions about past vegetation and climate change, the researcher said.

This shows that the tool can pinpoint the location of a fire where it occurred, according to Karp. "In a paleosol record you are really capturing an integrated picture of what was happening when the soil was forming," she said.

The researchers recently reported their findings in the Proceedings of the National Academy of Sciences. Katherine Freeman, Evan Pugh University Professor of Geosciences at Penn State and Karp's adviser, is a co-author on the paper.

"This is one of the biggest ecological changes in the last 66 million years," said Karp. "None of the open grassland systems we have today existed before this transition. It was a very different looking world, especially in sub-tropical places like Pakistan."

Scientists have long studied the rise of C4 grasslands, named after plants that evolved a new way to handle photosynthesis that allows them to thrive in dry, tropical conditions and with lower amounts of carbon dioxide. These plants include modern crops like corn and sugarcane.

A drop in global carbon dioxide levels was once believed to be behind the rise of C4 grasslands. More recent research has shown that the grasses spread at different rates on different continents, indicating that regional factors, like rain patterns -- and potentially fire -- played important roles. But there had been little direct evidence that linked a rise in wildfires to this transition.

"We were interested in reconstructing fire and the expansion of grasslands in the same geologic record to see if we could find proxy evidence of the role fire played," Karp said. "We now have a nice line of observational evidence to compare to what the models have said."

Karp and her collaborators used polycyclic aromatic hydrocarbons (PAHs), found in paleosols, as fire proxies. PAHs are chemicals that are created by the burning of organic matter like wood and plants. They also are naturally found in coal and crude oil.

PAHs increased five-fold across the study area while evidence of conifer trees declined and ultimately disappeared. The heavily forested landscape opened up in two stages. Around 10 million years ago, forests were replaced by more fire-prone, open woodlands or grasslands, and between six and eight million years ago, C4 grasslands became dominant just as the quantity of fire signatures sharply increased.

Modern fire ecology can explain the process. Grasses grow faster than trees after a fire and they also help create conditions ripe for subsequent fires, promoting open landscapes. In the late Miocene, wet seasons brought on by monsoon conditions encouraged plant growth, which in turn created more fuel for fires during hot, dry seasons in Pakistan.

"The role fire played in the expansion and evolution of grassland systems in deep time is important because understanding how fire has maintained systems in the past can help us predict what may happen to these important systems in the future as climate continues to change," Karp said.

Read more at Science Daily

Newly discovered supernova complicates origin story theories

Six images showing the host galaxy of the newly discovered supernova ASASSN-18bt. The top row shows three images from before the explosion taken by Pan-STARRS, ASAS-SN, and Kepler. The bottom row shows images from ASAS-SN and Kepler after the supernova was visible. The discovery image from the ASAS-SN team is in the bottom middle. To its left is a version with all the surrounding stars eliminated, showing only the new supernova's light output. On the bottom right is a Kepler image from after the supernova was detected. Kepler's precision was crucial to understanding the light from ASASSN_18bt in the early hours after the explosion.

A supernova discovered by an international group of astronomers including Carnegie's Tom Holoien and Maria Drout, and led by University of Hawaii's Ben Shappee, provides an unprecedented look at the first moments of a violent stellar explosion. The light from the explosion's first hours showed an unexpected pattern, which Carnegie's Anthony Piro analyzed to reveal that the genesis of these phenomena is even more mysterious than previously thought.

Their findings are published in a trio of papers in The Astrophysical Journal and The Astrophysical Journal Letters.

Type Ia supernovae are fundamental to our understanding of the cosmos. Their nuclear furnaces are crucial for generating many of the elements around us, and they are used as cosmic rulers to measure distances across the universe. Despite their importance, the actual mechanism that triggers a Type Ia supernova explosion has remained elusive for decades.

That's why catching them in the act is crucial.

Astronomers have long tried to get detailed data at the initial moments of these explosions, with the hope of figuring out how these phenomena are triggered. This finally happened in February of this year with the discovery of a Type Ia supernova called ASASSN-18bt (also known as SN 2018oh).

ASASSN-18bt was discovered by the All-Sky Automated Survey for Supernovae (ASAS-SN), an international network of telescopes headquartered at the Ohio State University that routinely scans the sky for supernovae and other cosmic explosions. NASA's Kepler space telescope was simultaneously able to take complementary data of this event. Kepler was designed to be incredibly sensitive to small changes in light for its mission of detecting extrasolar planets, so it was able to obtain especially detailed information about the explosion's genesis.

"ASASSN-18bt is the nearest and brightest supernova yet observed by Kepler, so it offered an excellent opportunity to test the predominant theories of supernova formation," said Shappee, who is lead author on the on the discovery and early time light curve paperand one of our Carnegie alumni.

Combining data from ASAS-SN, Kepler, and telescopes around the world, the astronomers realized that ASASSN-18bt looked unusual during its first couple of days.

"Many supernovae show a gradual increase in the light they put out," said Drout, who is jointly appointed at the University of Toronto. "But for this event, you could clearly see there's something unusual and exciting happening in the early times -- an unexpected additional emission."

Type Ia supernovae originate from the thermonuclear explosion of a white dwarf star -- the dead core left over by a Sun-like star after it exhausts its nuclear fuel. Material must be added to the white dwarf from a companion star to trigger the explosion, but the nature of the companion star and how the fuel is transferred has long been debated.

One possibility is that this additional light seen during the supernova's early times could be from the exploding white dwarf colliding with the companion star. Although this was the initial hypothesis, detailed comparisons with Piro's theoretical modeling work demonstrated that this additional light may have a different, unexplained origin.

"While the steep increase in ASASSN-18bt's early brightness could indicate that the explosion collides with another star, our follow-up data don't fit predictions for how this should look," Holoien said. "Other possibilities, such as an unusual distribution of radioactive material in the exploded star, are a better explanation for what we saw. More observations of ASASSN-18bt and more early discoveries like this one will hopefully help us differentiate between different models and better understand the origins of these explosions."

"Nature is always finding new ways to surprise us, and unique observations like this are great for motivating creative new approaches to how we think about these explosions, "added Piro. "As a theorist at the Carnegie Observatories, it's so helpful and inspiring to be right near the observers who are making these key measurements."

This supports a hypothesis put forward in recent work from the Carnegie Supernova Project, led by Maximilian Stritzinger ofAarhus University and co-led by Shappee and Piro, that there may be two distinct populations of Type Ia supernovae -- those that show early emission and those that do not.

Thanks to ASAS-SN and the next generation of surveys that are now monitoring the sky every night, astronomers will find even more new supernovae and catch them at the moment of explosion. As more of these events are found and studied, they will hopefully home in on the solution to the longstanding mystery of how these stellar explosions originate.

Read more at Science Daily

All of the starlight ever produced by the observable universe measured

This map of the entire sky shows the location of 739 blazars used in the Fermi Gamma-ray Space Telescope’s measurement of the extragalactic background light (EBL). The background shows the sky as it appears in gamma rays with energies above 10 billion electron volts, constructed from nine years of observations by Fermi’s Large Area Telescope. The plane of our Milky Way galaxy runs along the middle of the plot.

From their laboratories on a rocky planet dwarfed by the vastness of space, Clemson University scientists have managed to measure all of the starlight ever produced throughout the history of the observable universe.

Astrophysicists believe that our universe, which is about 13.7 billion years old, began forming the first stars when it was a few hundred million years old. Since then, the universe has become a star-making tour de force. There are now about two trillion galaxies and a trillion-trillion stars. Using new methods of starlight measurement, Clemson College of Science astrophysicist Marco Ajello and his team analyzed data from NASA's Fermi Gamma-ray Space Telescope to determine the history of star formation over most of the universe's lifetime.

A collaborative paper titled "A gamma-ray determination of the Universe's star-formation history" was published Nov. 30 in the journal Science and describes the results and ramifications of the team's new measurement process.

"From data collected by the Fermi telescope, we were able to measure the entire amount of starlight ever emitted. This has never been done before," said Ajello, who is lead author of the paper. "Most of this light is emitted by stars that live in galaxies. And so, this has allowed us to better understand the stellar-evolution process and gain captivating insights into how the universe produced its luminous content."

Putting a number on the amount of starlight ever produced has several variables that make it difficult to quantify in simple terms. But according to the new measurement, the number of photons (particles of visible light) that escaped into space after being emitted by stars translates to 4x10^84.

Or put another way: 4,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 photons.

Despite this stupendously large number, it is interesting to note that with the exception of the light that comes from our own sun and galaxy, the rest of the starlight that reaches Earth is exceedingly dim -- equivalent to a 60-watt light bulb viewed in complete darkness from about 2.5 miles away. This is because the universe is almost incomprehensibly huge. This is also why the sky is dark at night, other than light from the moon, visible stars and the faint glow of the Milky Way.

The Fermi Gamma-ray Space Telescope was launched into low orbit on June 11, 2008, and recently marked its 10-year anniversary. It is a powerful observatory that has provided enormous amounts of data on gamma rays (the most energetic form of light) and their interaction with the extragalactic background light (EBL), which is a cosmic fog composed of all the ultraviolet, visible and infrared light emitted by stars or from dust in their vicinity. Ajello and postdoctoral fellow Vaidehi Paliya analyzed almost nine years of data pertaining to gamma-ray signals from 739 blazars.

Blazars are galaxies containing supermassive black holes that are able to release narrowly collimated jets of energetic particles that leap out of their galaxies and streak across the cosmos at nearly the speed of light. When one of these jets happens to be pointed directly at Earth, it is detectable even when originating from extremely far away. Gamma ray photons produced within the jets eventually collide with the cosmic fog, leaving an observable imprint. This enabled Ajello's team to measure the density of the fog not just at a given place but also at a given time in the history of the universe.

"Gamma-ray photons traveling through a fog of starlight have a large probability of being absorbed," said Ajello, an assistant professor in the department of physics and astronomy. "By measuring how many photons have been absorbed, we were able to measure how thick the fog was and also measure, as a function of time, how much light there was in the entire range of wavelengths."

Using galaxy surveys, the star-formation history of the universe has been studied for decades. But one obstacle faced by previous research was that some galaxies were too far away, or too faint, for any present-day telescopes to detect. This forced scientists to estimate the starlight produced by these distant galaxies rather than directly record it.

Ajello's team was able to circumvent this by using Fermi's Large Area Telescope data to analyze the extragalactic background light. Starlight that escapes galaxies, including the most distant ones, eventually becomes part of the EBL. Therefore, accurate measurements of this cosmic fog, which have only recently become possible, eliminated the need to estimate light emissions from ultra-distant galaxies.

Paliya performed the gamma ray analysis of all 739 blazars, whose black holes are millions to billions of times more massive than our sun.

"By using blazars at different distances from us, we measured the total starlight at different time periods," said Paliya of the department of physics and astronomy. "We measured the total starlight of each epoch -- one billion years ago, two billion years ago, six billion years ago, etc. -- all the way back to when stars were first formed. This allowed us to reconstruct the EBL and determine the star-formation history of the universe in a more effective manner than had been achieved before."

When high-energy gamma rays collide with low-energy visible light, they transform into pairs of electrons and positrons. According to NASA, Fermi's ability to detect gamma rays across a wide range of energies makes it uniquely suited for mapping the cosmic fog. These particle interactions occur over immense cosmic distances, which enabled Ajello's group to probe deeper than ever into the universe's star-forming productivity.

"Scientists have tried to measure the EBL for a long time. However, very bright foregrounds like the zodiacal light (which is light scattered by dust in the solar system) rendered this measurement very challenging," said co-author Abhishek Desai, a graduate research assistant in the department of physics and astronomy. "Our technique is insensitive to any foreground and thus overcame these difficulties all at once."

Star formation, which occurs when dense regions of molecular clouds collapse and form stars, peaked around 11 billion years ago. But though the birthing of new stars has since slowed down, it has never stopped. For instance, about seven new stars are created in our Milky Way galaxy every year.

Establishing not only the present-day EBL, but revealing its evolution in cosmic history is a major breakthrough in this field, according to team member Dieter Hartmann, a professor in the department of physics and astronomy.

"Star formation is a great cosmic cycling and recycling of energy, matter and metals. It's the motor of the universe," Hartmann said. "Without the evolution of stars, we wouldn't have the fundamental elements necessary for the existence of life."

Understanding star formation also has ramifications for other areas of astronomical study, including research regarding cosmic dust, galaxy evolution and dark matter. The team's analysis will provide future missions with a guideline to explore the earliest days of stellar evolution -- such as the upcoming James Webb Space Telescope, which will be launched in 2021 and will enable scientists to hunt for the formation of primordial galaxies.

Read more at Science Daily

Whales lost their teeth before evolving hair-like baleen in their mouths

This is an artistic reconstruction of a mother and calf of Maiabalaena nesbittae nursing offshore of Oregon during the Oligocene, about 33 million years ago. While Maiabalaena would not have been able to chew or filter feed, muscle attachments on the bones of its throat indicate it likely had strong cheeks and a retractable tongue. These traits would have enabled it to suck water into its mouth, taking up fish and small squid in the process. The ability to suction feed would have rendered teeth, whose development requires a lot of energy to grow, unnecessary. The loss of teeth, then, appears to have set the evolutionary stage for the baleen, which the scientists estimate arose about 5 to 7 million years later.

Rivaling the evolution of feathers in dinosaurs, one of the most extraordinary transformations in the history of life was the evolution of baleen -- rows of flexible hair-like plates that blue whales, humpbacks and other marine mammals use to filter relatively tiny prey from gulps of ocean water. The unusual structure enables the world's largest creatures to consume several tons of food each day, without ever chewing or biting. Now, Smithsonian scientists have discovered an important intermediary link in the evolution of this innovative feeding strategy: an ancient whale that had neither teeth nor baleen.

In the Nov. 29 issue of the journal Current Biology, scientists at the Smithsonian's National Museum of Natural History and colleagues describe for the first time Maiabalaena nesbittae, a whale that lived about 33 million years ago. Using new methods to analyze long-ago discovered fossils housed in the Smithsonian's national collection, the team, which includes scientists at George Mason University, Texas A&M University and the Burke Museum of Natural History and Culture in Seattle, have determined that this toothless, 15-foot whale likely had no baleen, showing a surprising intermediary step between the baleen whales that live today and their toothed ancestors.

"When we talk about whale evolution, textbooks tend to focus on the early stages, when whales went from land to sea," said National Museum of Natural History's curator of fossil marine mammals. "Maiabalaena shows that the second phase of whale evolution is just as important for evolution over big scales. For the first time, we can now pin down the origin of filter-feeding, which is one of the major innovations in whale history."

When whales first evolved, they used teeth to chew their food, just like their land-dwelling ancestors. As time went on, many descendants of these early whales continued to chew their food, inheriting this trait from their predecessors. But as the oceans around them changed and animals evolved, entirely new feeding strategies arose, including baleen filter feeding, says National Museum of Natural History predoctoral fellow Carlos Mauricio Peredo, the lead author of the study who analyzed the Maiabalaena fossils.

Whales were the first mammals to evolve baleen, and no other mammal uses any anatomical structure even remotely similar to it to consume its prey. But frustratingly, baleen, whose chemical composition is more like that of hair or fingernails than bone, does not preserve well. It is rarely found in the fossil record, leaving paleontologists without direct evidence of its past or origins. Instead, scientists have had to rely on inferences from fossils and studies of fetal-whale development in the womb to piece together clues about how baleen evolved.

As a result, it has not been clear whether, as they evolved, early baleen whales retained the teeth of their ancestors until a filter-feeding system had been established. An early initial assumption, Peredo said, was that ocean-dwelling mammals must have needed teeth or baleen to eat -- but several living whales contradict that idea. Sperm whales have teeth in their bottom jaw, but none on the top, so they cannot bite or chew. Narwhals' only teeth are their long tusks, which they do not use for feeding. And some species of beaked whales, despite being classified as toothed whales, have no teeth at all.

Because of its age, Peredo said, paleontologists suspected Maiabalaena might hold important clues about baleen's evolution. The fossil comes from a period of massive geological change during the second major phase of whale evolution, around the time the Eocene epoch was transitioning to the Oligocene. With continents shifting and separating, ocean currents were swirling around Antarctica for the first time, cooling the waters significantly. The fossil record indicates that whales' feeding styles diverged rapidly during this timeframe, with one group leading to today's filter-feeding whales and the other leading to echolocating ones.

Consequently, Maiabalaena had received plenty of scrutiny since its discovery in Oregon in the 1970s, but the rock matrix and material that the fossil was collected in still obscured many of its features. It was not until Peredo finally cleaned the fossil and then examined it with state-of-the-art CT scanning technology that its most striking features became clear. Maiabalaena's lack of teeth was readily apparent from the preserved bone, but the CT scans, which revealed the fossil's internal anatomy, told the scientists something new: Maiabalaena's upper jaw was thin and narrow, making it an inadequate surface from which to suspend baleen.

"A living baleen whale has a big, broad roof in its mouth, and it's also thickened to create attachment sites for the baleen," Peredo said. "Maiabalaena does not. We can pretty conclusively tell you this fossil species didn't have teeth, and it is more likely than not that it didn't have baleen either."

While Maiabalaena would not have been able to chew or to filter feed, muscle attachments on the bones of its throat indicate it likely had strong cheeks and a retractable tongue. These traits would have enabled it to suck water into its mouth, taking up fish and small squid in the process. The ability to suction feed would have rendered teeth, whose development requires a lot of energy to grow, unnecessary. The loss of teeth, then, appears to have set the evolutionary stage for the baleen, which the scientists estimate arose about 5 to 7 million years later.

Peredo and Pyenson see studying whale evolution as key to understanding their survival in today's rapidly changing oceans. Like the emergence of baleen, tooth loss in whales is evidence of adaptability, suggesting that whales might be able to adapt to challenges posed in the ocean today. Still, Peredo cautions, evolutionary change may be slow for the largest whales, which have long life spans and take a long time to reproduce.

Read more at Science Daily

Stone tools linked to ancient human ancestors in Arabia have surprisingly recent date

These are handaxes from the site of Saffaqah, Saudi Arabia.

Beginning more than 1.5 million years ago, early humans made stone handaxes in a style known as the Acheulean -- the longest lasting tool-making tradition in prehistory. New research led by the Max Planck Institute for the Science of Human History and the Saudi Commission for Tourism and National Heritage has documented an Acheulean presence in the Arabian Peninsula dating to less than 190,000 years ago, revealing that the Arabian Acheulean ended just before or at the same time as the earliest Homo sapiens dispersals into the region.

Much attention has been given to understanding the spread of our own species, Homo sapiens, first within Africa and then beyond. However, less attention has been given to where diverse groups of close evolutionary cousins lived in Eurasia immediately prior to the arrival of Homo sapiens. Understanding this is critical because the spatial and temporal characteristics of such groups reveal the human and cultural landscape first encountered by our species on leaving Africa.

The youngest Acheulean site in Southwest Asia

In a paper published in Scientific Reports, an international team of researchers led by the Max Planck Institute for the Science of Human History and the Saudi Commission for Tourism and National Heritage reports the first ever dates obtained from an Acheulean site in Arabia, the site of Saffaqah, situated in Central Saudi Arabia. Saffaqah is the first stratified Acheulean site to be reported in the Arabian Peninsula and the dates reveal that early humans occupied the site until at least 190,000 years ago. These dates are surprisingly recent for a region known to feature among the oldest examples of such technology outside Africa. For example, dates from the Levant document an ancient Acheulean presence from 1.5 million years ago. Conversely the site of Saffaqah features the youngest Acheulean tools yet found in southwest Asia.

Over 500 stone tools, including handaxes and other artefacts known as cleavers, were recovered from the occupation levels. Some of the stone flakes used to make handaxes were in such fresh condition that they were recovered still resting on the stone nodules from which they had been detached. These and other artefacts show that the early humans responsible for making them were manufacturing stone tools at this site.

"It is not surprising that early humans came here to make stone tools," says Dr. Eleanor Scerri of the Max Planck Institute for the Science of Human History, the lead author of the study. "The site is located on a prominent andesite dyke that rises above the surrounding plain. The spot was both a source of raw material as well as a prime location to survey a landscape that, back then, sat between two major river systems." This choice location also seems to have continued to be attractive to early humans at an even later date than those recorded by the researchers in this study. Layers containing identical stone handaxes are also found above the dense occupation layers that were dated, raising the possibility that Saffaqah is among the youngest Acheulean sites documented anywhere.

Hominins living at the edge

The new dating results both record the late persistence of the Acheulean in the Peninsula and also show that as yet unidentified hominin populations were using networks of now extinct rivers to disperse into the heart of Arabia during a time of increased rainfall in the region. This suggests that these hominins were able to live on the margins of habitable zones and take advantage of relatively brief "greening" episodes in a generally arid area. The dispersal of these hominins into the heart of Arabia may also help to explain the surprisingly late persistence of the Acheulean, as it suggests a degree of isolation.

"These hominins were resourceful and intelligent," adds Dr. Scerri, "They dispersed across a challenging landscape using technology commonly seen as reflecting a lack of inventiveness and creativity. Instead of perceiving the Acheulean this way, we should really be struck by how flexible, versatile and successful this technology was."

Cutting edge science

To date the sediments from the site of Saffaqah, the researchers used a combination of dating techniques known as luminescence methods, including a newly developed infrared-radiofluorescence (IR-RF) dating protocol for potassium rich feldspars. The method relies on the ability of such minerals to store energy induced by natural radioactivity and to release this energy in the form of light. "The application of IR-RF dating allowed us to obtain age estimates from sediments that were previously difficult to reliably date," explains Marine Frouin of the University of Oxford, one of the researchers involved in the dating program.

Read more at Science Daily

Oldest-known ancestor of modern primates may have come from North America, not Asia

Teilhardina brandti, a 56-million year-old primate found in Wyoming, may be older than its Asian cousin, previously thought to be the earliest ancestor of modern primates. Unusual tooth sockets in this lower jaw of Teilhardina brandti helped make the determination.

About 56 million years ago, on an Earth so warm that palm trees graced the Arctic Circle, a mouse-sized primate known as Teilhardina first curled its fingers around a branch.

The earliest-known ancestor of modern primates, Teilhardina's close relatives would eventually give rise to today's monkeys, apes and humans. But one of the persistent mysteries about this distant cousin of ours is where it originated.

Teilhardina (ty-hahr-DEE'-nuh) species quickly spread across the forests of Asia, Europe and North America, a range unparalleled by all other primates except humans. But where did its journey begin?

New research shows that Teilhardina brandti, a species found in Wyoming, is as old or older than its Asian and European relatives, upending the prevailing hypothesis that Teilhardina first appeared in China.

Teilhardina's origins, however, remain a riddle.

"The scientific conclusion is 'We just don't know,'" said Paul Morse, the study's lead author and a recent University of Florida doctoral graduate. "While the fossils we've found potentially overturn past hypotheses of where Teilhardina came from and where it migrated, they definitely don't offer a clearer scenario."

What is clear, Morse said, is that T. brandti had a wide variety of features, some of which are as primitive as those found in Teilhardina asiatica, its Asian cousin, previously thought to be the oldest species in the genus.

To make this determination, Morse studied 163 teeth and jaws in the most comprehensive analysis of T. brandti to date.

Teeth contain a treasure-trove of information and often preserve better than bone, thanks to their tough enamel. They can reveal clues about an animal's evolutionary past, its size, diet and age as an individual and in geological time.

Primate teeth have particularly distinct structures that are immediately recognizable to the trained eye, said Jonathan Bloch, study co-author and curator of vertebrate paleontology at the Florida Museum of Natural History.

"Identifying differences between primate teeth is not so different from a biker recognizing that a Harley is different from a scooter or an art critic evaluating whether an image was created by Picasso or Banksy," he said. "In detail, they are very different from each other in specific, predictable ways."

While Teilhardina bones are very rare in the fossil record, its teeth are more plentiful -- if you know how to find them. Bloch's team of paleontologists, Morse included, have spent years combing the surface of Wyoming's Bighorn Basin on hands and knees and then packing out 50-pound bags of soil to a river to screen wash. The remaining bits of bones and teeth -- which can be smaller than a flea -- are examined under a microscope back at the museum.

This painstaking search has built up the dental record of T. brandti from a single molar -- used to first describe the species in 1993 -- to hundreds of teeth, providing a broad look at the primate's population-level variation.

Still, Morse and Bloch were unprepared for the peculiar variation exhibited by specimen UF 333700, a jagged piece of jaw with T. brandti teeth.

"Jon and I started arguing about the alveoli" -- empty tooth sockets -- "and how they didn't look right at all," said Morse, now a postdoctoral researcher at Duke University. "By the end of the day, we realized that specimen completely overturned both the species definition of T. asiatica and part of the rationale for why it is the oldest Teilhardina species."

Studies based on a small number of teeth simply missed the diversity in Teilhardina's physical characteristics, Morse said.

"There's likely a tremendous amount of variation in the fossil record, but it's extremely difficult to capture and measure when you have a small sample size," he said. "That's one of the reasons collecting additional fossils is so important."

The analysis also reshuffled the Teilhardina family tree, reducing the number of described species from nine to six and reclassifying two species as members of a new genus, Bownonomys, named for prominent vertebrate paleontologist Thomas Bown.

But the precise ages of Teilhardina species are still impossible to pinpoint and may remain that way.

Teilhardina appeared during the geological equivalent of a flash in the pan, a brief 200,000-year period known as the Paleocene-Eocene Thermal Maximum, or PETM. This era was characterized by a massive injection of carbon into the Earth's atmosphere, which sent global temperatures soaring. Sea levels surged by 220 feet, ecosystems were overhauled and the waters at the North Pole warmed to 74 degrees.

Scientists can use the distinct carbon signature of the PETM to locate this period in the rock record, and carbon isotopes in teeth can also be used to identify fossil animals from the era.

But among Teilhardina fossil sites across the globe, only Wyoming has the uninterrupted, neatly demarcated layers of rock that allow paleontologists to hone in on more precise dates.

"The humblest statement would be to say that these species are essentially equivalent in age," Bloch said. "Determining which came earlier in the PETM probably surpasses the level of resolution we have in the rock record. But what we can say is that the only place where you can really establish where Teilhardina appears in this climate event with confidence is in the Bighorn Basin."

As the Earth warmed, plants and animals expanded their ranges northward, returning south as temperatures cooled at the end of the PETM.

"This dance of plants and animals with climate change happened over vast landscapes, with forests moving from the Gulf Coast to the Rocky Mountains in just a few thousand years," Bloch said.

Teilhardina likely tracked the shifts in its forest habitats across the land bridges that then connected North America, Greenland and Eurasia, he said.

"Teilhardina is not throwing its bag over its shoulder and walking," he said. "Its range is shifting from one generation to the next. Over 1,000 years, you get a lot of movement, and over 2,000-3,000 years, you could easily cover continental distances."

While it was well-suited to Earth's hothouse environment, Teilhardina disappeared with the PETM, replaced by new and physically distinct primates. It's a sobering reminder of what can happen to species -- including humans -- during periods of swift climatic changes, Bloch said.

Read more at Science Daily