A new approach, not currently described by the Clean Air Act, could eliminate air pollution disparities

by University of Washington

Credit: Unsplash/CC0 Public Domain

While air quality has improved dramatically over the past 50 years thanks in part to the Clean Air Act, people of color at every income level in the United States are still exposed to higher-than-average levels of air pollution.

A team led by researchers at the University of Washington wanted to know if the Clean Air Act is capable of reducing these disparities or if a new approach would be needed. The team compared two approaches that mirror main aspects of the Clean Air Act and a third approach that is not commonly used to see if it would be better at addressing disparities across the contiguous U.S. The researchers used national emissions data to model each strategy: targeting specific emissions sources across the U.S.; requiring regions to adhere to specific concentration standards; or reducing emissions in specific communities.

While the first two approaches—based on the Clean Air Act—didn't get rid of disparities, the community-specific approach eliminated pollution disparities and reduced pollution exposure overall.

The team published these findings Oct. 24 in the Proceedings of the National Academy of Sciences.

"In earlier research, we wanted to know which pollution sources were responsible for these disparities, but we found that nearly all sources lead to unequal exposures. So we thought, what's it going to take? Here, we tried three approaches to see which would be the best for addressing these disparities," said senior author Julian Marshall, a UW professor of civil and environmental engineering. "The two approaches that mirror aspects of the Clean Air Act were pretty weak at addressing disparities. The third approach, targeting emissions in specific locations, is not commonly done, but is something overburdened communities have been asking for for years."

Fine particulate matter pollution, or PM2.5, is less than 2.5 micrometers in diameter—about 3% of the diameter of a human hair. PM2.5 comes from vehicle exhaust; fertilizer and other agricultural emissions; electricity generation from fossil fuels; forest fires; and burning of fuels such as wood, oil, diesel, gasoline and coal. These tiny particles can lead to heart attacks, strokes, lung cancer and other diseases, and are estimated to be responsible for about 90,000 deaths each year in the U.S.

The researchers tested the three potential strategies using a tool called InMAP, which Marshall and other co-authors developed. InMAP models the chemistry and physics of PM2.5, including how it is formed in the atmosphere, how it dissipates and how wind patterns move it from one location to another. The team modeled these approaches with national emissions data from 2014 because it was the most recent data set available at the time of this study.

The researchers looked at how efficiently and effectively each approach reduced average pollution exposure for all people and how well it eliminated the disparities for people of color.

While the emission source and concentration standards approaches were successful in reducing overall exposure across the country, these methods failed to address pollution disparities.

"Our optimization models what happens if we maximize the reductions in disparities. If an approach cannot address disparities even when optimized to do so, then any real-world implementation of the approach will also not address disparities," said lead author Yuzhou Wang, a doctoral student in civil and environmental engineering. "But we saw that even with less than 1% of emission reductions targeting specific locations, the pollution disparities that have persisted for decades were reduced to zero."

Implementing this location-specific approach would require additional work to identify which locations would be the best to target and working with the communities there to identify how to reduce emissions, the team said.

"Current regulations have improved average air pollution levels, but they have not addressed structural inequalities and often have ignored the voices and lived experiences of people in overburdened communities, including their requests to focus greater attention on sources impacting their communities," Marshall said. "These findings reflect historical experiences. Because of redlining and other racist urban planning from many decades ago, many pollution sources are more likely to be located in Black and brown communities. If we wish to address current inequalities, we need an approach that reflects and acknowledges this historical context."

Additional co-authors are Joshua Apte and Cesunica Ivey, both at the University of California, Berkeley; Jason Hill at the University of Minnesota; Regan Patterson at the University of California, Los Angeles; Allen Robinson at Carnegie Mellon University; and Christopher Tessum at the University of Illinois Urbana-Champaign.People of color hardest hit by air pollution from nearly all sources

More information: Wang, Yuzhou, Location-specific strategies for eliminating US national racial-ethnic PM2.5 exposure inequality, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2205548119. doi.org/10.1073/pnas.2205548119

Journal information: Proceedings of the National Academy of Sciences

Provided by University of Washington 

 

A step closer to understanding why some lizards are immune to black widow spider venom

by Bob Yirka , Phys.org

Whole-animal performance (sprint) in response to control (saline injection), low (1LD50) or

 high (5LD50) treatments of venom from the western black widow spider (Latrodectus 

hesperus). Changes in sprint speed quantified as the difference in post-injection velocity 

compared with baseline sprint speed (pre-injection), and recorded across three time points

 (0: immediately after injection; 24: 1 day after injection; 48: 2 days after injection). 

(a) Plots grouped by species: Elgaria multicarinata (southern alligator lizard); Sceloporus

 occidentalis (western fence lizard); Uta stansburiana (side-blotched lizard). 

(b) Plots grouped by treatment. Note that U. stansburiana is the only species that showed 

significant reduction in sprint speed compared with baseline speed (table 1), denoted by 

* (p < 0.05). Photos courtesy RW Hansen. Credit: Royal Society Open Science (2022).

 DOI: 10.1098/rsos.221012

A team of researchers at the University of Nevada has taken a step toward understanding how it is some lizards are able to withstand a black widow spider bite with few to no ill effects. In their paper published in the journal Royal Society Open Science, the group describes how they injected several species of lizards with black widow venom and then took a close look to see how they responded.

Prior research has shown that the black widow spider is one of the most poisonous spiders in North America. Luckily, black widow spiders are not hostile and thus do not attack humans and they also produce very little venom. Because of that, very few people have ever died from a bite.

Prior research and anecdotal evidence has also shown that some lizards not only are not bothered by black widows but actively seek out the spiders as a food source. In this new effort, the researchers sought to learn more about such lizards to find out if their ability to withstand black widow bites might offer some clues for better treating humans who have been bitten.

The work by the researchers started with them going out into the field and collecting several specimens of three types of lizards: alligator, Western fence and side-blotched. The first two are known to be immune to black-widow spider bites while the third is very susceptible—they die if bitten.

The researchers then injected several of each of the three types of lizards with black widow venom and then set them down on a small racecourse and encouraged them to run. Both the alligator and Western fence were able to do so, while the side-blotched were not.

The researchers then dissected several of each of the lizards after injecting them with the venom. They noted that prior research has shown that creatures adversely impacted by black widow spider bites suffer from tissue and muscle damage. They found such damage in both the side blotched and Western fence but none in the alligator. Taking a closer look, the researchers discovered that there were no signs at all that the alligator lizards had been injected with the venom.

The researchers note that the lack of reaction to the venom by the alligator lizards suggests that they have a very strong protection mechanism. They note that some other species of animals have evolved a known mechanism to protect against venom—king snakes, for example, are immune to rattlesnake venom.

They have something in their blood that binds to the venom, neutralizing it. The researchers suggest it is likely the alligator lizards have something similar. They will not know what it is, however, until the genome of the lizard is sequenced.

Eating fire ants could prepare lizards for future fire ant attack

More information: Vicki L. Thill et al, Preying dangerously: black widow spider venom resistance in sympatric lizards, Royal Society Open Science (2022). DOI: 10.1098/rsos.221012

Journal information: Royal Society Open Science 

© 2022 Science X Network

Gestational exposure to flame retardant alters brain development in rats

by Tracey Peake, North Carolina State University

Credit: CC0 Public Domain

A new study from North Carolina State University shows that exposure in utero to the flame-retardant FireMaster 550 (FM 550), or to its individual brominated (BFR) or organophosphate ester (OPFR) components, resulted in altered brain development in newborn rats. The effects—most notably evidence of mitochondrial disruption and dysregulated choline and triglyceride levels in brain tissue—were greater in male offspring than in females.

The work adds to the body of evidence that both OPFRs and BFRs can be neurotoxic. It appears in a special issue of Neuroendocrinology. Shannah Witchey, former NC State postdoctoral researcher, is first author.

FM 550 is a flame-retardant mixture first identified a decade ago. It was developed to replace PBDEs, a class of fire retardants being phased out due to safety concerns.

"While some new flame-retardant mixtures still contain BFRs, the OPFRs are a popular substitute for PBDEs, since it is believed that OPFRs don't accumulate in the body and thus cannot be as harmful," says Heather Patisaul, associate dean for research in NC State's College of Sciences and corresponding author of the study. "Specifically, it was thought that OPFRs wouldn't impact acetylcholinesterase—a key neurotransmitter. But it looks as though OPFRs still impact choline signaling and are just as bad if not worse than PBDEs for the developing brain."

Patisaul and her colleagues performed transcriptomic and lipidomic studies on the prefrontal cortexes of newborn rats whose mothers had been exposed to FM550, or to BFR or OPFR elements individually, during gestation.

"Getting genetic information from transcriptomics is what researchers commonly do to tease out potential connections between toxicity and health effects," Patisaul says. "In this case, we also wanted to see if the lipid (or fat) composition of the brain was altered—our brains are essentially balls of fat, and lipidomics can reveal how exposure may affect the brain in its earliest developmental stages."

Both the transcriptomic and lipidomic analyses showed evidence of mitochondrial disruption, although the disruptions were more pronounced in the offspring that had been exposed to OPFRs. Mitochondria are found in almost every cell and serve as cells' energy generators, playing a vital role in cellular respiration.

The transcriptomic analysis found disruption of cellular respiration genes associated with neurodegenerative disorders like Alzheimer's and ALS, while lipidomics pointed to disrupted choline and triglyceride levels in the brain.

In males exposed to OPFRs, genes associated with axon guidance and choline signaling were also dysregulated. Axon guidance is the process by which neurons make the proper connections during neural development. Choline is a precursor to the neurotransmitter acetylcholine, which affects critical aspects of neuron function and neuronal signaling.

"That so many altered genes are involved in respiration and choline, there is concern that these FRs impair basic autonomic function and cognition," Patisaul says. "So, the bottom line is that exposure to BFRs and OPFRs is disrupting both neuronal signaling and the ability of cells to properly produce and utilize energy."

The researchers also found that male offspring were more affected than females.

"In earlier rat studies, we found that OPFR levels are higher in placentas attached to males than females," Patisaul says. "So that difference in exposure could be why we see different and more severe effects in males.

"The important message here is that the presumption that OPFRs are safer that other FRs is likely wrong. Both OPFRs and BFRs can disrupt cortical development and function. And the fact that these chemicals are detectable in the placenta means they aren't breaking down quickly enough to do no damage."Placental accumulation of flame retardant chemical alters serotonin production in rats

More information: Shannah K. Witchey et al, Impacts of Gestational FireMaster 550 (FM 550) Exposure on the Neonatal Cortex are Sex Specific and Largely Attributable to the Organophosphate Esters, Neuroendocrinology (2022). DOI: 10.1159/000526959

Provided by North Carolina State University 

 

Fossil bird's skull reconstruction reveals a brain made for smelling and eyes made for daylight

by Field Museum

Artistic reconstruction of Jeholornis in life. Credit: Michael Rothman

Jeholornis was a raven-sized bird that lived 120 million years ago, among the earliest examples of dinosaurs evolving into birds, in what's now China. The fossils that have been found are finely preserved but smashed flat, the result of layers of sediment being deposited over the years. That means that no one's been able to get a good look at Jeholornis's head. But in a new study, researchers digitally reconstructed a Jeholornis skull, revealing details about its eyes and brain that shed light on its vision and sense of smell.

"Jeholornis is my favorite Cretaceous bird, it has a lot of unusual, primitive traits, and it helps shed light on the bigger story of how different birds evolved," says Jingmai O'Connor, associate curator of fossil reptiles at the Field Museum and one of the authors of the paper describing the discovery in the Zoological Journal of the Linnean Society. "This study is the first time we're really getting at what this bird's skull looked like, what its brain must have been like, which is really exciting."

The study's first author, Han Hu, went through roughly 100 fossils at China's Shandong Tianyu Museum of Nature and selected the one with the best-preserved skull—still a little flattened, but intact. "It is very difficult to find the right skull among around 100 fossils, since we won't know if one skull will provide us the information we want before the scanning, and due to the costs of high quality scanning, we couldn't scan all those specimens to choose the best one. However, I chose this one because at least from the exposed surface, it is relatively complete, and which is also important is that this skull is preserved to be isolated from other parts of its body," says Hu, a researcher at the Department of Earth Sciences, University of Oxford, UK.

"This is very helpful since we usually won't chop the skull off from the skeleton if they are articulated—no one wants to hurt these previous fossils, but an isolated skull will reduce the size of the scanning area, which will increase the scanning quality a lot. Luckily, the specimen we chose here for this project is nearly a perfect one—it provided us so much unknown information after the digital reconstruction."

"These bones were kind of like the bottom of a bag of potato chips—they weren't completely crushed, but the pieces were compacted," says O'Connor. "So we were able to CT scan them—essentially taking a bunch of X-rays and stacking them together to form a 3D image—and then digitally re-articulate them and reconstruct the skull from all these bones."

Reconstruction of Jeholornis's skull, showing the bony rings around its eye. 

Credit: Han Hu et al

"We were able to see different features of the skull that had never been seen before in Jeholornis, and we were even able to extrapolate what its brain looked like," says co-author and Field Museum postdoctoral researcher Matteo Fabbri.

The brain itself isn't preserved—soft tissues rarely are—but bird and dinosaur brains tend to nest neatly within their skulls. Knowing the shape and dimensions of a fossil bird's skull, therefore, tells us a lot about its brain, kind of like how a glove gives a decent approximation of how a hand is shaped. What's more, brain structures are conserved across species and over time—things like olfactory bulbs and the cerebellum in the same general spots whether you're looking at the brain of a frog, a human, or a fossil bird.

Thanks to the long-standing placements of these structures, the researchers were able to determine how Jeholornis's brain compares with modern birds and dinosaurs (or, strictly speaking, non-avian dinosaurs; all birds, including Jeholornis, are dinosaurs, but not all dinosaurs are birds).

"Jeholornis's brain morphology is transitional, in-between what we see in non-avian dinosaurs and what we see in modern birds," says Fabbri. "If you look at the skulls of dinosaurs, what you see is a spot for a very reptile-like brain, meaning that they have very large olfactory bulbs, and the optic lobes that are in the midbrain are reduced. They probably had a very good sense of smell and not great sight, which is very reptilian. And on the other hand, if you look at modern birds, they do the reverse. They have small olfactory bulbs, and very large optic lobes. Jeholornis falls in the middle."

3D reconstruction of Jeholornis's brain. Credit: Han Hu et al

Jeholornis had bigger olfactory bulbs than most modern birds, meaning that it probably relied more on its sense of smell than birds today (with the exception of a few keen-smellers, like vultures). Jeholornis's strong sense of smell makes sense in the context of another recent study by the team, showing that Jeholornis is the earliest-known fruit-eating animal. "As fruits ripen, they release lots of chemicals," says O'Connor. "We can't prove it yet, but having a better sense of smell might have helped Jeholornis find fruit."

In addition to a brain adapted for smelling, the researchers found that Jeholornis was likely better at seeing in the daytime than at night. Birds have bones called scleral rings that help determine how much light goes into their eyes. Species that need to see at night, like owls, have wider scleral ring openings relative to their eye sockets, to let in more light; birds that are active during the day have narrower openings for light to go through, like the aperture on a camera. Jeholornis's scleral rings seem to indicate that it was most active during the day.

All of these skull features provide a better understanding of this early bird's lifestyle and the role it played in its ecosystem. "Reconstructing a skull is painstaking work, and as people are starting to put in the time to do it, It's becoming more and more clear that the evolution of birds was more complicated than what we expected," says Fabbri. "It's not just different from dinosaurs and modern birds, it's different from other early birds too. It's not a straightforward evolutionary story."

"The same as Jingmai, Jeholornis is also one of my favorite birds. Its special position as one of the most primitive birds during the dinosaur-bird transition determines that completing its story will reveal the true scenery of that critical evolutionary period, and also, tell us why and how the modern birds—the only living dinosaurs—evolved to be what we see now," says HuThe early bird gets the fruit: Fossil provides earliest evidence of fruit-eating by any animal

More information: Han Hu et al, Cranial osteology and palaeobiology of the Early Cretaceous bird Jeholornis prima (Aves: Jeholornithiformes), Zoological Journal of the Linnean Society (2022). DOI: 10.1093/zoolinnean/zlac089

Journal information: Zoological Journal of the Linnean Society 

Provided by Field Museum 

 

Analysis of gases recovered from asteroid Ryugu by Hayabusa2 spacecraft

Back scattered electron image of a Ryugu pellet sample (A0105-10). The sample is mainly

 composed of phyllosilicates (dark gray regions). Spherical magnetite aggregates, thin 

magnetite plates, and iron sulfide grains are also present. Carbonates are found close to

 magnetites and sulfides. Red arrows indicate minerals labeled “mt” for magnetite, “po” for

 pyrrhotite (iron sulfide), and “ca” for carbonate (rimmed with red dotted ovals), respectively

. Credit: Science (2022). DOI: 10.1126/science.abo0431

Three international teams of researchers studying samples of gases recovered by the Hayabusa2 spacecraft from the near-Earth asteroid Ryugu have published their results. The first studied the asteroid's volatile sources and recent surface evolution. The second looked at its nucleosynthetic heritage. And the third team provided an overview of the types of gases that were returned. The first team has published their results in the journal Science; the second and third teams have both have published their results in the journal Science Advances.

The first team found that the asteroid still had noble gases and isotopes from the early days of the solar system, along with a nitrogen composition, which they describe as similar to Ivuna-type carbonaceous chondrites. They also found evidence that one of the noble gases was created by the solar wind and another via irradiation of galactic cosmic rays. And they also found what they describe as a "close" relationship been CI chondrites and gas from Ryugu.

The second team found that some of the samples from Ryugu had Fe isotopic irregularities that were the same as those found in other Ivuna-type (CI) chondrites. They also found iron isotopes that must have formed in places where there were no carbonaceous asteroids. And that, they note, suggests that Ryugu may have come from farther away in the solar system than has been theorized. They suggest it could have come from as far away as beyond the orbits of Saturn or Jupiter. They noted that the growth and migration paths of the giant planets had a destabilizing effect on planetesimals, some of which ejected material into the main belts, which could have included Ryugu.

The third team identified all of the gases that were brought back and measured the amounts of each. They also noted their extraterrestrial origin. They found that some of the helium that had been captured came from the solar wind and some of it leaked in from the Earth's atmosphere as the craft carrying it made its way home. They conclude by reiterating the fact that the gases collected on the project represent the first from a near-Earth asteroid.Scientists discover the source of one of the rarest groups of meteorites

More information: Ryuji Okazaki et al, Noble gases and nitrogen in samples of asteroid Ryugu record its volatile sources and recent surface evolution, Science (2022). DOI: 10.1126/science.abo0431

Ryuji Okazaki, First asteroid gas sample delivered by the Hayabusa2 mission: A treasure box from Ryugu, Science Advances (2022). DOI: 10.1126/sciadv.abo7239. www.science.org/doi/10.1126/sciadv.abo7239

Timo Hopp, Ryugu's nucleosynthetic heritage from the outskirts of the Solar System, Science Advances (2022). DOI: 10.1126/sciadv.add8141. www.science.org/doi/10.1126/sciadv.add8141

Journal information: Science Advances 

© 2022 Science X Network

VELIKOVSKY WAS RIGHT

Geomagnetic fields reveal the truth behind Biblical narratives

by Tel-Aviv University

Burnt mud brick wall from Tel Batash (Biblical Timnah) with markings of the field orientation

. Credit: Yoav Vaknin.

A joint study by TAU and the Hebrew University, involving 20 researchers from different countries and disciplines, has accurately dated 21 destruction layers at 17 archaeological sites in Israel by reconstructing the direction and/or intensity of the earth's magnetic field recorded in burnt remnants. The new data verify the Biblical accounts of the Egyptian, Aramean, Assyrian, and Babylonian military campaigns against the Kingdoms of Israel and Judah.

Findings indicate, for example, that the army of Hazael, King of Aram-Damascus, was responsible for the destruction of several cities—Tel Rehov, Tel Zayit, and Horvat Tevet, in addition to Gath of the Philistines, whose destruction is noted in the Hebrew Bible. At the same time, the study refutes the prevailing theory that Hazael was the conqueror who destroyed Tel Beth-Shean.

Other geomagnetic findings reveal that the cities in the Negev were destroyed by the Edomites, who took advantage of the destruction of Jerusalem and the Kingdom of Judah by the Babylonians.

The groundbreaking interdisciplinary study was published in the Proceedings of the National Academy of Sciences and is based on the doctoral thesis of Yoav Vaknin, supervised by Prof. Erez Ben-Yosef and Prof. Oded Lipschits of TAU's Institute of Archaeology and Prof. Ron Shaar from the Institute of Earth Sciences at the Hebrew University.

Yoav Vaknin explaining about the research. Credit: Tel Aviv University

The researchers explain that geophysicists, attempting to understand the mechanism of earth's magnetic field, track changes in this field throughout history. To this end they use archaeological findings containing magnetic minerals which, when heated or burned, record the magnetic field at the time of the fire.

Thus, in a 2020 study, researchers reconstructed the magnetic field as it was on the 9th of the month of Av, 586 BCE, the Hebrew date of the destruction of the First Temple and the City of Jerusalem by Nebuchadnezzar and his Babylonian army.

Now, using archaeological findings unearthed over several decades at 17 sites throughout Israel, alongside historical information from ancient inscriptions and Biblical accounts, the researchers were able to reconstruct the magnetic fields recorded in 21 destruction layers. They used the data to develop a reliable new scientific tool for archaeological dating.

Yoav Vaknin measuring at the site. Credit: Shai Halevi, Israel Antiquities Authority.

Yoav Vaknin explains that "based on the similarity or difference in intensity and direction of the magnetic field, we can either corroborate or disprove hypotheses claiming that specific sites were burned during the same military campaign. Moreover, we have constructed a variation curve of field intensity over time which can serve as a scientific dating tool, similar to the radiocarbon dating method."

One example given by the researchers is the destruction of Gath of the Philistines (identified today as Tel Tzafit in the Judean foothills) by Hazael, King of Aram-Damascus. Various dating methods have placed this event at around 830 BCE, but were unable to verify that Hazael was also responsible for the destruction of Tel Rehov, Tel Zayit and Horvat Tevet.

Now the new study, identifying full statistical synchronization between the magnetic fields recorded at all of these four sites at the time of destruction, makes a very strong case for their destruction during the same campaign.

A destruction level at Tel Beth-Shean, on the other hand, recording a totally different magnetic field, refutes the prevailing hypothesis that it too was destroyed by Hazael. Instead, the magnetic data from Beth-Shean indicate that this city, along with two other sites in northern Israel, was probably destroyed 70-100 years earlier, a date which could correspond with the military campaign of the Egyptian Pharaoh Shoshenq.

Shoshenq's campaign is described in the Hebrew Bible and in an inscription on a wall of the Temple of Amun in Karnak, Egypt, which mentions Beth-Shean as one of his conquests.

One of the most interesting findings revealed by the new dating method has to do with the end of the Kingdom of Judah. Prof. Erez Ben Yosef says, "The last days of the Kingdom of Judah are widely debated. Some researchers, relying on archaeological evidence, argue that Judah was not completely destroyed by the Babylonians.

"While Jerusalem and frontier cities in the Judean foothills ceased to exist, other towns in the Negev, the southern Judean Mountains and the southern Judean foothills remained almost unaffected. Now, the magnetic results support this hypothesis, indicating that the Babylonians were not solely responsible for Judah's ultimate demise.

"Several decades after they had destroyed Jerusalem and the First Temple, sites in the Negev, which had survived the Babylonian campaign, were destroyed—probably by the Edomites who took advantage of the fall of Jerusalem. This betrayal and participation in the destruction of the surviving cities may explain why the Hebrew Bible expresses so much hatred for the Edomites—for example, in the prophecy of Obadiah."

Map of the studied destruction layers and the different military campaigns. Credit: Itamar Ben-Ezra

Prof. Oded Lipschits adds that "the new dating tool is unique because it is based on geomagnetic data from sites, whose exact destruction dates are known from historical sources. By combining precise historical information with advanced, comprehensive archaeological research, we were able to base the magnetic method on reliably anchored chronology."

A separate paper, presenting the scientific principles of the novel archaeomagnetic dating method, is in preparation. Prof. Ron Shaar, who led the geophysical aspects of the study, as well as the development of the geomagnetic dating method, explains that "Earth's magnetic field is critical to our existence. Most people don't realize that without it there could be no life on earth—since it shields us from cosmic radiation and the solar wind. In addition, both humans and animals use it to navigate. The geomagnetic field is generated by earth's outer core, at a depth of 2,900 km, by currents of liquid iron."

Burnt mud stones. Credit: Tel Aviv University.

"Due to the chaotic motion of this iron, the magnetic field changes over time. Until recently scientists believed that it remains quite stable for decades, but archaeomagnetic research has contradicted this assumption by revealing some extreme and unpredictable changes in antiquity. Our location here in Israel is uniquely conducive to archaeomagnetic research, due to an abundance of well-dated archaeological findings. Over the past decade we have reconstructed magnetic fields recorded by hundreds of archaeological items."

"By combining this dataset with the data from Yoav's investigation of historical destruction layers we were able to form a continuous variation curve showing rapid, sharp changes in the geomagnetic field. This is wonderful news, both for archaeologists who can now use geomagnetic data to determine the age of ancient materials and for geophysicists studying the earth's core."Chicken bones and snail shells help archaeologists to date ancient town's destruction

More information: Vaknin, Yoav, Reconstructing biblical military campaigns using geomagnetic field data, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2209117119. doi.org/10.1073/pnas.2209117119

Journal information: Proceedings of the National Academy of Sciences

Provided by Tel-Aviv University 

Study offers new, sharper proof of early plate tectonics, flipping of geomagnetic poles

by Juan Siliezar, Harvard University

An interior cutaway of the early Earth highlighting its major geodynamic processes. 

Magnetic field lines are drawn in blue and red emanating from the liquid core that generated

 them, while plate tectonic forces rearrange the surface and play a role in the churning 

circulation of the rocky mantle below. Credit: Alec Brenner

New research analyzing pieces of the most ancient rocks on the planet adds some of the sharpest evidence yet that Earth's crust was pushing and pulling in a manner similar to modern plate tectonics at least 3.25 billion years ago. The study also provides the earliest proof of when the planet's magnetic north and south poles swapped places.

The two results offer clues into how such geological changes may have resulted in an environment more conducive to the development of life on the planet.

The work, described in PNAS and led by Harvard geologists Alec Brenner and Roger Fu, focused on a portion of the Pilbara Craton in western Australia, one of the oldest and most stable pieces of the Earth's crust. Using novel techniques and equipment, the researchers show that some of the Earth's earliest surface was moving at a rate of 6.1 centimeters per year and 0.55 degrees every million years.

That speed more than doubles the rate the ancient crust was shown to be moving in a previous study by the same researchers. Both the speed and direction of this latitudinal drift leaves plate tectonics as the most logical and strongest explanations for it.

"There's a lot of work that seems to suggest that early in Earth's history plate tectonics wasn't actually the dominant way in which the planet's internal heat gets released as it is today through the shifting of plates," said Brenner, a Ph.D. candidate in the Graduate School of Arts and Sciences and member of Harvard's Paleomagnetics Lab. "This evidence lets us much more confidently rule out explanations that don't involve plate tectonics."

For example, the researchers can now argue against phenomena called "true polar wander" and "stagnant lid tectonics," which can both cause the Earth's surface to shift but aren't part of modern-style plate tectonics. The results lean more toward plate tectonic motion because the newly discovered higher rate of speed is inconsistent with aspects of the other two processes.

In the paper, the scientists also describe what's believed to be the oldest evidence of when Earth reversed its geomagnetic fields, meaning the magnetic North and South Pole flipped locations. This type of flip-flop is a common occurrence in Earth's geologic history with the pole's reversing 183 times in the last 83 million years and perhaps several hundred times in the past 160 million years, according to NASA.

The reversal tells a great deal about the planet's magnetic field 3.2 billion years ago. Key among these implications is that the magnetic field was likely stable and strong enough to keep solar winds from eroding the atmosphere. This insight, combined with the results on plate tectonics, offers clues to the conditions under which the earliest forms of life developed.

"It paints this picture of an early earth that was already really geodynamically mature," Brenner said. "It had a lot of the same sorts of dynamic processes that result in an Earth that has essentially more stable environmental and surface conditions, making it more feasible for life to evolve and develop."

Today, the Earth's outer shell consists of about 15 shifting blocks of crust, or plates, which hold the planet's continents and oceans. Over eons the plates drifted into each other and apart, forming new continents and mountains and exposing new rocks to the atmosphere, which led to chemical reactions that stabilized Earth's surface temperature over billions of years.

Evidence of when plate tectonics started is hard to come by because the oldest pieces of crust are thrust into the interior mantle, never to resurface. Only 5 percent of all rocks on Earth are older than 2.5 billion years old, and no rock is older than about 4 billion years.

Overall, the study adds to growing research that tectonic movement occurred relatively early in Earth's 4.5-billion-year history and that early forms of life came about in a more moderate environment. Members of the project revisited the Pilbara Craton in 2018, which stretches about 300 miles across. They drilled into the primordial and thick slab of crust there to collect samples that, back in Cambridge, were analyzed for their magnetic history.

Using magnetometers, demagnetizing equipment, and the Quantum Diamond Microscope—which images the magnetic fields of a sample and precisely identifies the nature of the magnetized particles—the researchers created a suite of new techniques for determining the age and way the samples became magnetized. This allows the researchers to determine how, when, and which direction the crust shifted as well as the magnetic influence coming from Earth's geomagnetic poles.

The Quantum Diamond Microscope was developed in a collaboration between Harvard researchers in the Departments of Earth and Planetary Sciences (EPS) and of Physics.

For future studies, Fu and Brenner plan keep their focus on the Pilbara Craton while also looking beyond it to other ancient crusts around the world. They hope to find older evidence of modern-like plate motion and when the Earth's magnetic poles flipped.

"Finally being able to reliably read these very ancient rocks opens up so many possibilities for observing a time period that often is known more through theory than solid data," said Fu, professor of EPS in the Faculty of Arts and Sciences. "Ultimately, we have a good shot at reconstructing not just when tectonic plates started moving, but also how their motions—and therefore the deep-seated Earth interior processes that drive them—have changed through time."Tectonic plates started shifting earlier than previously thought

More information: Brenner, Alec R., Plate motion and a dipolar geomagnetic field at 3.25 Ga, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2210258119. doi.org/10.1073/pnas.2210258119

Journal information: Proceedings of the National Academy of Sciences 

Provided by Harvard University 

For blight-ridden American chestnut tree, rebirth may be in offing

Author: AFP|

Update: 25.10.2022

If scientists are successful, American chestnut trees will recover from a terrible blight that has devastated the species / © AFP

The American chestnut tree, once a regal pillar of forests across the eastern United States, is on life support, struggling to survive.

"These look like death," said Vasiliy Lakoba, research director for the American Chestnut Foundation (ACF), which has been working since the 1980s to resurrect the species.

He pointed to a patch of stunted shrubs, chestnut trees that were a far cry from the noble, erect chestnut trees of yesteryear.


Settlers along the US eastern seaboard relied on abundant chestnut trees to feed their hogs, their children and themselves. Chestnuts made up about 50 percent of hardwood forests in much of the eastern seaboard, and the wood was ideal for building.

But then came a terrible fungus, identified in 1904 at the Bronx Zoo on a tree from Japan. In less than three decades, millions of American chestnut trees had perished. It has been considered the greatest tragedy in the history of American forestry.


Prickly burrs cover the meat of the American chestnut tree / © AFP

"The devastation was so fast," said Lakoba, referring to "ghost forests."

Today, only a few rare specimens still survive to adulthood in the wild.

- 'Tall and straight' -

The American Chesnut Foundation runs this research facility in Meadowview, Virginia / © AFP

Nestled in the Appalachian Mountains, the foundation's main laboratory farm spans 36 hectares (almost 90 acres) in Virginia and includes tens of thousands of trees.

Workers use a crane to harvest the burrs, or spiny prickly shells that cover the nuts, then take them to a shed to be studied and used for future planting.

"It's like picking apples, but with pricks," laughed Jim Tolton, a technician on the farm, during a chestnut harvest day in early October.


A canker disfigures a branch on an American chestnut tree at the American Chestnut Foundation's Meadowview, Virginia, Research Farm / © AFP

Before the disease, the American chestnut tree "grew tall and straight through the forest, fighting for light," Lakoba said.

But the blight causes cankers to appear on the branches and stems of the American chestnut tree.

Blighted trees grow other branches here and there, giving them a bushy appearance, instead of maintaining a tall, straight shape.

No cure has yet been found to stop the spread.

- Hybrids and GMOs -


A researcher holds a healthy leaf of a Chinese chestnut tree. Under it is a sickly leaf of an American chestnut tree / © AFP

Finding a way to fight the blight is precisely the mission of ACF.

To do this, two main research avenues are under investigation: The first, which has been in place for years, consists of crossing an American chestnut tree with other species that already show some resistance to the fungus, such as the Chinese chestnut tree.

A first specimen is produced from this hybridization, before it is crossbred again with an American chestnut tree, then once again -- all in order to preserve as much of the original genetic characteristics as possible. The current hybrid has 15/16ths of the genetic makeup of an American chestnut tree -- while ideally acquiring the resistance of the Chinese chestnut tree.

One of the main drawbacks with these hybrids, explained Lakoba, "is that blight resistance and susceptibility have turned out to be a genetically much more complex phenomenon than previously thought."

ACF researchers have not abandoned their crossbreeding efforts. But a second avenue of research has opened up: genetic modification.

Vasiliy Lakoba, research director at a farm of the American Chesnut Foundation in Meadowview, Virginia, voices hope that a devastating blight can be overcome / © AFP

Working on a transgenic version of the American chestnut tree, researchers at the State University of New York at Syracuse have developed a specimen that shows very promising early results of disease resistance, according to Lakoba, who is collaborating with the researchers.

Combining crossbreeding with genetic modification might yield better results, he said.

- 'Keep chipping away' -


Ultraviolet light bathes American chestnut saplings in a research facility in Meadowview, Virginia / © AFP

Once a resistant specimen has been developed, the time will come for the Herculean task of reintroducing the tree to an American landscape deeply altered by more than a century of development.

"So much has changed in terms of climate, in terms of invasive species, in terms of pollution, habitat change, land use, change, soil loss and erosion, that it really isn't the same world from 100 years ago," Lakoba said.

Not only has the landscape been altered, Lakoba said, climate change adds another wildcard to whether the American chestnut can ever prosper again.

Once abundant in hardwood forests in the eastern United States, chestnut trees like this one (seen through a screen in Meadowview, Virginia) grow today to barely the size of shrubs / © AFP

"Overall, there will be more pests, there will be more diseases," he said.

Any revival of the American chestnut may be decades -- or centuries -- away.

"This is definitely at least a couple centuries of a mission going forward. And from there, I think we just keep chipping away at it," Lakoba said.

But he is hopeful that scientific advances are on the side of the American chestnut.

"We see it really as a matter of time."