It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Sunday, June 04, 2023
Ancient DNA Sheds New Light on Human Evolution during Out-of-Africa Migration
The dispersal of anatomically modern Homo sapiens out of Africa and across Eurasia provides a unique opportunity to examine the impacts of genetic selection as our species adapted to multiple new environments. An analysis of ancient (1,000 to 45,000 years old) Eurasian genomic datasets reveals signatures of strong selection, including at least 57 hard sweeps after the initial human movement out of Africa, which have been obscured in modern populations by extensive admixture during the Holocene. In new research, scientists identified a previously unsuspected extended period of genetic adaptation lasting around 30,000 years, potentially in the Arabian Peninsula area, prior to a major Neanderthal genetic introgression and subsequent rapid dispersal across Eurasia as far as Australia.
Evolutionary changes that helped our early ancestors survive the first migration out of Africa could hold important clues for modern medicine. Image credit: sjs.org / CC BY-SA 3.0.
“Ancient human genomes make it possible to recover key events in the evolution of our species that are essentially hidden from modern human genomes,” said Dr. Raymond Tobler, a researcher at the Australian National University.
“We suspect the ’Arabian Standstill’ period was a pivotal point in our evolutionary history, during which the ancestors of all non-African humans underwent extensive genetic adaptation to colder environments, effectively preparing them for the cool Eurasian environments they would eventually encounter.”
In their research, Dr. Tobler and his colleagues used ancient human genomes to reconstruct historical adaptation during the poorly understood out-of-Africa diaspora.
They found specific genetic patterns that pointed to a series of natural selection events dating back 80,000 years.
These patterns suggest the ancestors of modern humans living outside of Africa experienced an extended period of genetic isolation and adaptation, possibly around the Arabian Peninsula, prior to their worldwide dispersal 50,000 years ago.
“These ancient adaptive genes share striking functional similarities with selected genes found in human and mammalian populations currently living in the Arctic,” said Garvan Institute’s Professor Shane Grey.
The authors propose a connection between genetic selection and human migration during the Eurasian Paleolithic period, suggesting that the speed of movement was influenced not only by climatic cycles but also by the need to adapt to new environments.
“While crucial for survival at the time, these adaptive genes are associated with obesity, diabetes, and neurodegenerative disease in contemporary populations,” said Dr. Yassine Souilmi, a researcher at the University of Adelaide and the Australian National University.
“Our study not only improves our understanding of human evolution, but the link between adaptation and modern disease could expedite the development of therapeutic and preventive measures by prioritizing medical research on previously selected genes.”
The study appears online in the Proceedings of the National Academy of Sciences.
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Raymond Tobler et al. 2023. The role of genetic selection and climatic factors in the dispersal of anatomically modern humans out of Africa. PNAS 120 (22): e2213061120; doi: 10.1073/pnas.2213061120
153,000-Year-Old Homo sapiens Footprint Discovered in South Africa
The 153,000-year-old footprint, which was found in the Garden Route National Park, a national park in the Garden Route region of the South African Western Cape and Eastern Cape provinces, is the oldest footprint thus far attributed to our species, Homo sapiens.
The 153,000-year-old footprint, lightly ringed with chalk, in the Garden Route National Park, South Africa; it appears long and narrow because the trackmaker dragged their heel. Image credit: Charles Helm.
“Just over two decades ago, as the new millennium began, it seemed that tracks left by our ancient human ancestors dating back more than about 50,000 years were excessively rare,” Nelson Mandela University researcher Charles Helm and his colleagues toldThe Conversation.
“Only four sites had been reported in the whole of Africa at that time: Laetoli in Tanzania, Koobi Fora in Kenya, and Nahoon and Langebaan sites in South Africa.”
“Today, the African tally for dated hominin ichnosites — a term that includes both tracks and other traces — older than 50,000 years stands at 14.”
“These can conveniently be divided into an East African cluster (five sites) and a South African cluster from the Cape coast (nine sites).”
The researchers used a technique called optically stimulated luminescence to estimate the age of seven hominin ichnosites from the South African cluster on the Cape south coast.
“The Cape south coast is a great place to apply optically stimulated luminescence,” they explained.
“Firstly, the sediments are rich in quartz grains, which produce lots of luminescence.”
“Secondly, the abundant sunshine, wide beaches and ready wind transport of sand to form coastal dunes mean any pre-existing luminescence signals are fully removed prior to the burial event of interest, making for reliable age estimates.”
“This method has underpinned much of the dating of previous finds in the area.”
Incipient cementation in a Holocene dune near Still Bay, South Africa. Image credit: Helm et al., doi: 10.1080/10420940.2023.2204231.
They found that the South African ichnosites ranged in age; the most recent dates back about 71,000 years.
The oldest, which dates back 153,000 years, is one of the more remarkable finds recorded by the team.
It is the oldest footprint thus far attributed to anatomically modern Homo sapiens.
“There are significant differences between the East African and South African tracksite clusters,” the authors said.
“The East African sites are much older: Laetoli, the oldest, is 3.66 million years old and the youngest is 700,000 years old. The tracks were not made by Homo sapiens, but by earlier species such as australopithecines, Homo heidelbergensis and Homo erectus.”
“The South African sites on the Cape coast, by contrast, are substantially younger. All have been attributed to Homo sapiens.”
The team’s work was published in the Ichnos, an International Journal of Plant and Animal Traces.
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Charles W. Helm et al. Dating the Pleistocene hominin ichnosites on South Africa’s Cape south coast. Ichnos, published online April 25, 2023; doi: 10.1080/10420940.2023.2204231
Queen Hetepheres’ Silver Bracelets Shed Light on Trade Networks in Ancient Egypt
Egypt has no domestic silver ore sources and silver is rarely found in the Egyptian archaeological record until the Middle Bronze Age. Bracelets found in the tomb of queen Hetepheres I — mother of king Khufu, builder of the Great Pyramid at Giza (date of reign 2589-2566 BCE) — form the largest and most famous collection of silver artifacts from early Egypt. In new research, scientists from Macquarie University and elsewhere analyzed samples from queen Hetepheres’ bracelets using several state-of-the-art techniques to understand the nature and metallurgical treatment of the metal and identify the possible ore source. Their results indicate that the silver was most likely obtained from the Cyclades (Seriphos, Anafi, or Kea-Kithnos) or perhaps the Lavrion mines in Attica. It excludes Anatolia as the source with a fair degree of certainty. This new finding demonstrates, for the first time, the potential geographical extent of commodity procurement networks utilized by the Egyptian state during the early Old Kingdom at the height of the Pyramid-building age.
Two silver bracelets of queen Hetepheres. Image credit: Sowada et al., doi: 10.1016/j.jasrep.2023.103978.
Silver artifacts first appeared in Egypt during the 4th millennium BCE but the original source then, and in the 3rd millennium, is unknown.
Ancient Egyptian texts don’t mention any local sources, but an older view, derived from the presence of gold in silver objects, plus the high silver content of Egyptian gold and electrum, holds that silver was derived from local sources.
An alternative view is that silver was imported to Egypt, possibly via Byblos on the Lebanese coast, owing to many silver objects found in Byblos tombs from the late fourth millennium.
The tomb of queen Hetepheres I was discovered at Giza in 1925 by the Harvard University-Museum of Fine Arts joint expedition.
Hetepheres was one of Egypt’s most important queens: wife of 4th Dynasty king Sneferu and mother of Khufu, the greatest builders of the Old Kingdom (c. 2686-2180 BCE).
Her intact sepulchre is the richest known from the period, with many treasures including gilded furniture, gold vessels and jewelry.
Made of a metal rare to Egypt, her bracelets were found surrounded by the remains of a wooden box covered with gold sheeting, bearing the hieroglyphic inscription ‘Box containing deben-rings.’
Twenty deben-rings or bracelets were originally interred, one set of ten for each limb, originally packed inside the box.
The thin metal worked into a crescent shape and the use of turquoise, lapis lazuli and carnelian inlay, stylistically mark the bracelets as made in Egypt and not elsewhere.
Each ring is of diminishing size, made from a thin metal sheet formed around a convex core, creating a hollow cavity on the underside
Depressions impressed into the exterior received stone inlays forming the shape of butterflies.
At least four insects are depicted on each bracelet, rendered using small pieces of turquoise, carnelian and lapis lazuli, with each butterfly separated by a circular piece of carnelian.
In several places, pieces of real lapis have been substituted by painted plaster.
“The origin of silver used for artifacts during the third millennium has remained a mystery until now,” said Dr. Karin Sowada, an archaeologist at Macquarie University.
“The new finding demonstrates, for the first time, the potential geographical extent of trade networks used by the Egyptian state during the early Old Kingdom at the height of the Pyramid-building age.”
Dr. Sowada and colleagues found that queen Hetepheres’ bracelets consist of silver with trace copper, gold, lead and other elements.
The minerals are silver, silver chloride and a possible trace of copper chloride.
Surprisingly, the lead isotope ratios are consistent with ores from the Cyclades (Aegean islands, Greece), and to a lesser extent from Lavrion (Attica, Greece), and not partitioned from gold or electrum as previously surmised.
The silver was likely acquired through the port of Byblos on the Lebanese coast and is the earliest attestation of long-distance exchange activity between Egypt and Greece.
The analysis also revealed the methods of early Egyptian silver working for the first time.
“Samples were analysed from the collection in the Museum of Fine Arts in Boston, and the scanning electron microscope images show that the bracelets were made by hammering cold-worked metal with frequent annealing to prevent breakage,” said Professor Damian Gore, an archaeologist at Macquarie University.
“The bracelets were also likely to have been alloyed with gold to improve their appearance and ability to be shaped during manufacture.”
“The rarity of these objects is threefold: surviving royal burial deposits from this period are rare; only small quantities of silver survived in the archaeological record until the Middle Bronze Age (c. 1900 BCE); and Egypt lacks substantive silver ore deposits,” Dr. Sowada said.
The findings were published in the Journal of Archaeological Science: Reports.
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Karin Sowada et al. 2023. Analyses of queen Hetepheres’ bracelets from her celebrated tomb in Giza reveals new information on silver, metallurgy and trade in Old Kingdom Egypt, c. 2600 BC. Journal of Archaeological Science: Reports 49: 103978; doi: 10.1016/j.jasrep.2023.103978
Iron-Rich Meteoritic and Volcanic Particles May Have Promoted Origin of Life Reactions on Early Earth
Precursors of the molecules needed for the origin of life may have been generated by chemical reactions promoted by meteoritic and volcanic particles approximately 4.4 billion years ago, says a team of researchers led by Professor Oliver Trapp from the Ludwig-Maximilians-Universität München.
An artist’s impression of the Hadean Earth: huge, impact-generated lava lakes coexisted with surface liquid water, under a thick greenhouse atmosphere sustained by lava outgassing. Image credit: Simone Marchi & Dan Durda, Southwest Research Institute.
“The formation of reactive organic molecules to form the building blocks of life on the nascent Earth is one of the prerequisites for abiogenesis,” Professor Trapp and colleagues said.
“The emergence of a stable continental crust and liquid water on the Earth at 4.4 billion years ago, and the earliest biogenic carbon isotope signatures at 3.8-4.1 billion years ago suggest that life originated only 400-700 million years after the formation of the Earth.”
"This relatively short time span indicates that the major part of organic precursors has been already formed on the Hadean Earth as early as 4.4 billion years ago.”
“One possibility is that the prebiotic organic constituents that had been formed in the solar nebula, carbon-rich asteroids, and comets have been delivered onto the early Earth,” they said.
“Other theories consider the synthesis in the atmosphere and in the ocean by catalytic or high energy processes (lightning, volcanic energy, impact shocks).”
Formation of prebiotic key organic matter from carbon dioxide by catalysis with meteoritic and volcanic particles. Image credit: Peters et al., doi: 10.1038/s41598-023-33741-8.
In their study, the authors investigated whether meteorite or ash particles deposited on volcanic islands could have promoted the conversion of atmospheric carbon dioxide to the precursors of organic molecules on the early Earth.
They simulated a range of conditions that previous research has suggested may have been present on the early Earth by placing carbon dioxide gas in a heated and pressurized system — an autoclave — under pressures ranging between 9 and 45 bars and temperatures between 150 and 300 degrees Celsius.
They also simulated wet and dry climate conditions by adding either hydrogen gas or water to the system.
They mimicked the depositing of meteorite or ash particles on volcanic islands by adding different combinations of crushed samples of iron meteorites, stony meteorites, or volcanic ash into the system, as well as minerals that may have been present in the early Earth and are found in either the Earth’s crust, meteorites, or asteroids.
The scientists found that the iron-rich particles from meteorites and volcanic ash promoted the conversion of carbon dioxide into hydrocarbons, aldehydes and alcohols across a range of atmosphere and climate conditions that may have been present in the early Earth.
They observed that aldehydes and alcohols formed at lower temperatures while hydrocarbons formed at 300 degrees Celsius.
“As the early Earth’s atmosphere cooled over time, the production of alcohols and aldehydes may have increased,” they said.
“These compounds may then have participated in further reactions that could have led to the formation of carbohydrates, lipids, sugars, amino acids, DNA, and RNA.”
“By calculating the rate of the reactions they observed and using data from previous research on the conditions of the early Earth, we estimate that their proposed mechanism could have synthesized up to 600,000 tons of organic precursors per year across the early Earth.”
“Their mechanism may have contributed to the origins of life on Earth, in combination with other reactions in the early Earth’s atmosphere and oceans.”
The findings appear in the journal Scientific Reports.
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S. Peters et al. 2023. Synthesis of prebiotic organics from CO2 by catalysis with meteoritic and volcanic particles. Sci Rep 13, 6843; doi: 10.1038/s41598-023-33741-8
A role for meteoritic iron in the emergence of life on Earth
A small fragment of the Campo del Cielo iron meteorite. The same intense heat that partially the meteorite to produce the smooth surface visible here would have also evaporated and ablated iron, creating tiny, nanometer-sized particles. These particles could have acted as catalysts for producing the building blocks of life on the early Earth. Credit: O. Trapp
Researchers from the Max Planck Institute for Astronomy and Ludwig Maximilians University Munich have proposed a new scenario for the emergence of the first building blocks for life on Earth, roughly 4 billion years ago.
By experiment, they showed how iron particles from meteors and from volcanic ash could have served as catalysts for converting a carbon-dioxide rich early atmosphere into hydrocarbons, but also acetaldehyde and formaldehyde, which in turn can serve as building blocks for fatty acids, nucleobases, sugars and amino acids. Their article, "Synthesis of prebiotic organics from CO2 by catalysis with meteoritic and volcanic particles," is published in the journal Scientific Reports.
To the best of our current knowledge, life on Earth emerged a mere 400 to 700 million years after the Earth itself had formed. That is a fairly quick development. For comparison, consider that afterwards, it took about 2 billion years for the first proper (eukaryotic) cells to form. The first step towards the emergence of life is the formation of organic molecules that can serve as building blocks for organisms. Given how fast life itself arose, it would be plausible for this comparatively simple first step to have been completed quickly, as well.
The research described here presents a new way for such organic compounds to form on planetary scales under the conditions prevalent on the early Earth. The key supporting role goes to iron particles produced from meteorites, which act as a catalyst. Catalysts are substances whose presence speeds up specific chemical reactions, but which do not get used up in those reactions. In that way, they are akin to the tools used in manufacture: Tools are necessary to produce, say, a car, but after one car is built, the tools can be used to build the next one.
From industrial chemistry to the beginnings of the Earth
Key inspiration for the research came, of all things, from industrial chemistry. Specifically, Oliver Trapp, a professor at Ludwig Maximilians University, Munich, and Max Planck Fellow at the Max Planck Institute for Astronomy (MPIA), wondered whether the so-called Fischer–Tropsch process for converting carbon monoxide and hydrogen into hydrocarbons in the presence of metallic catalysts might not have had an analog on an early Earth with a carbon-dioxide-rich atmosphere.
"When I looked at the chemical composition of the Campo-del-Cielo iron meteorite, consisting of iron, nickel, some cobalt and tiny amounts of iridium, I immediately realized that this is a perfect Fischer-Tropsch catalyst," explains Trapp. The logical next step was to set up an experiment to test the cosmic version of Fischer-Tropsch.
Dmitry Semenov, a staff member at the Max Planck Institute for Astronomy, says, "When Oliver told me about his idea to experimentally investigate the catalytic properties of iron meteorite particles to synthesize building blocks for life, my first thought was that we should also study the catalytic properties of volcanic ash particles. After all, the early Earth should have been geologically active. There should have been plenty of fine ash particles in the atmosphere and on Earth's first land masses."
Re-creating cosmic catalysis
For their experiments, Trapp and Semenov teamed up with Trapp's Ph.D. student Sophia Peters, who would run the experiments as part of her Ph.D. work. For access to meteorites and minerals, as well as expertise in the analysis of such materials, they reached out to mineralogist Rupert Hochleitner, an expert on meteorites at the Mineralogische Staatssammlung in Munich.
The first ingredient for the experiments was always a source of iron particles. In different versions of the experiment, those iron particles might be iron from an actual iron meteorite, or particles from an iron-containing stone meteorite, or volcanic ash from Mount Etna, the latter as a stand-in for the iron-rich particles that would be present on the early Earth with its highly active volcanism. Next, the iron particles were mixed with different minerals such as might be found on the early Earth. These minerals would act as a support structure. Catalysts are commonly found as small particles on a suitable substrate.
Producing small particles
Particle size matters. The fine volcanic ash particles produced by volcanic eruptions are typically a few micrometers in size. For meteorites falling through the atmosphere of the early Earth, on the other hand, atmospheric friction would ablate nanometer-size iron particles. The impact of an iron meteorite (or of the iron core of a larger asteroid) would produce micrometer-sized iron particles directly through fragmentation, and nanometer-sized particles as iron evaporated in the intense heat and later-on condensed again in the surrounding air.
The researchers aimed to reproduce this variety of particle sizes in two different ways. By dissolving the meteoric material in acid, they produced nanometer-sized particles from their prepared material. And by putting either the meteoritic material or the volcanic ash into a ball mill for 15 minutes, the researchers could produce larger, micrometer-sized particles. Such a ball mill is a drum containing both the material and steel balls, which is rotated at high speeds, in this case more than ten times per second, with the steel balls grinding up the material.
Since Earth's initial atmosphere did not contain oxygen, the researchers then followed up with chemical reactions that would remove almost all of the oxygen from the mixture.
Producing organic molecules under pressure
As the last step in each version of the experiment, the mixture was brought into a pressure chamber filled with (mostly) carbon dioxide CO2 and (some) hydrogen molecules, chosen so as to simulate the atmosphere of the early Earth. Both the exact mixture and the pressure were varied between experiments.
The results were impressive: Thanks to the iron catalyst, organic compounds such as methanol, ethanol and acetaldehyde were produced, but also formaldehyde. That is an encouraging harvest—acetaldehyde and formaldehyde in particular are important building blocks for fatty acids, nucleobases (themselves the building blocks of DNA), sugars and amino acids.
Importantly, these reactions took place successfully under a variety of pressure and temperature conditions. Sophia Peters says, "Since there are many different possibilities for the properties of the early Earth, I tried to experimentally test every possible scenario. In the end, I used fifty different catalysts, and ran the experiment at various values for the pressure, the temperature, and the ratio of carbon dioxide and hydrogen molecules." That the organic molecules formed under such a variety of condition is a strong indication that reactions like these could have taken place on the early Earth—whatever its precise atmospheric conditions will turn out to be.
Adding a scenario to the portfolio of possible mechanisms
With these results, there is now a new contender for how the first building blocks of life were formed on Earth. Joining the ranks of "classic" mechanisms such as organic synthesis near hot vents on the ocean floor, or electric discharge in a methane-rich atmosphere (as in the Urey-Miller experiment), and of models that predict how organic compounds could have formed in the depth of space and transported to Earth by asteroids or comets (see this MPIA press release), there is now another possibility: meteoric iron particles or fine volcanic ash acting as catalysts in an early, carbon-dioxide-rich atmosphere.
With this spread of possibilities, learning more about the atmospheric composition and physical properties of the early Earth should allow researchers to deduce, eventually, which of the various mechanisms will give the highest yield of building blocks under the given conditions—and which thus was likely the most important mechanism for the first steps from non-life to life on our home planet.
More information: Synthesis of prebiotic organics from CO2 by catalysis with meteoritic and volcanic particles, Scientific Reports (2023). www.nature.com/articles/s41598-023-33741-8
Chinese researchers find way to manufacture highly flexible, paper-thin solar cells
By Global Times
Published: May 25, 2023
Chinese researchers have developed a special technology to tailor the edges of textured crystalline silicon (c-Si) solar cells, based on which the solar cells can be bent and folded like thin paper, allowing for broader application and use.
The breakthrough was achieved by Chinese researchers at the Shanghai Institute of Microsystem and Information Technology (SIMIT) under the Chinese Academy of Sciences. The results have been featured on the cover of the May 24 edition of Nature journal.
The c-Si solar cells fabricated with the new technology can be 60 millimeters thin with a bending radius of about 8 millimeters.
Highly flexible, paper-thin c-Si solar cells Photo: Courtesy of the CAS
According to the Technology Daily, c-Si solar cells are type of solar cell seeing fast development at the moment. They have advantages including long service life and high conversion efficiency, making them a leading product in the photovoltaic market.
Such c-Si solar cells have a market share of more than 95 percent, according to Di Zengfeng, deputy head of the SIMIT, who is one of the authors of the research paper.
Although c-Si solar cells were developed nearly 70 years ago, their use is still limited, the paper explained. Currently, the c-Si solar cells are mainly used in distributed photovoltaic power stations and ground photovoltaic power stations. Hopefully, such solar cells can be used in construction, backpacks, tents, automobiles, sailing boats and even planes.
They can also be used to generate clean energy for houses and a variety of portable electronic and communication devices as well as for transportation, according to the researchers.
Highly flexible, paper-thin c-Si solar cells Photo: Courtesy of the CAS
Liu Zhengxin, a research fellow with the SIMIT, and another author of the paper, said that the study verified the feasibility of mass production, providing a technical route for the development of lightweight and flexible c-Si solar cells.
At the same time, the large-area flexible photovoltaic modules developed by the research team have been successfully applied in the fields of near-space vehicles, building photovoltaic integration and vehicle-mounted photovoltaic systems, Liu said.
Vitamin D alters developing neurons in the brain's dopamine circuit, finds study
Neuroscientists at The University of Queensland have uncovered how vitamin D deficiency affects developing neurons in schizophrenia, using new technology. The paper was published in the Journal of Neurochemistry.
Professor Darryl Eyles has built on past research out of his laboratory at the Queensland Brain Institute linking maternal vitamin D deficiency and brain development disorders, such as schizophrenia, to understand the functional changes taking place in the brain.
Schizophrenia is associated with many developmental risk factors, both genetic and environmental. While the precise neurological causes of the disorder are unknown, what is known is that schizophrenia is associated with a pronounced change in the way the brain uses dopamine, the neurotransmitter often referred to as the brain's "reward molecule."
Professor Eyles has followed the mechanisms that might relate to abnormal dopamine release and discovered that maternal vitamin D deficiency affects the early development and later differentiation of dopaminergic neurons.
The team at the Queensland Brain Institute developed dopamine-like cells to replicate the process of differentiation into early dopaminergic neurons that usually takes place during embryonic development.
They cultured the neurons both in the presence and absence of the active vitamin D hormone. In three different model systems they showed dopamine neurite outgrowth was markedly increased. They then showed alterations in the distribution of presynaptic proteins responsible for dopamine release within these neurites.
"What we found was the altered differentiation process in the presence of vitamin D not only makes the cells grow differently, but recruits machinery to release dopamine differently," Professor Eyles said.
Using a new visualization tool known as false fluorescent neurotransmitters, the team could then analyze the functional changes in presynaptic dopamine uptake and release in the presence and absence of vitamin D.
They showed that dopamine release was enhanced in cells grown in the presence of the hormone compared to a control.
"This is conclusive evidence that vitamin D affects the structural differentiation of dopaminergic neurons."
Leveraging advances in targeting and visualizing single molecules within presynaptic nerve terminals has enabled Professor Eyles and his team to further explore their long-standing belief that maternal vitamin D deficiency changes how early dopaminergic circuits are formed.
The team is now exploring whether other environmental risk factors for schizophrenia such as maternal hypoxia or infection similarly alter the trajectory of dopamine neuron differentiation.
Eyles and his team believe such early alterations to dopamine neuron differentiation and function may be the neurodevelopmental origin of dopamine dysfunction later in adults who develop schizophrenia.
More information: Renata Aparecida Nedel Pertile et al, Vitamin D: A potent regulator of dopaminergic neuron differentiation and function, Journal of Neurochemistry (2023). DOI: 10.1111/jnc.15829
Stephen Hawking's last collaborator on physicist's final theory
by Daniel Lawler
Stephen Hawking in his Cambridge office, where he first met his final collaborator Thomas Hertog.
When Thomas Hertog was first summoned to Stephen Hawking's office in the late 1990s, there was an instant connection between the young Belgian researcher and the legendary British theoretical physicist.
"Something clicked between us," Hertog said.
That connection would continue even as Hawking's debilitating disease ALS robbed him of his last ways to communicate, allowing the pair to complete a new theory that aims to turn how science looks at the universe on its head.
The theory, which would be Hawking's last before his death in 2018, has been laid out in full for the first time in Hertog's book "On the Origin of Time", published in the UK last month.
In an interview with AFP, the cosmologist spoke about their 20-year collaboration, how they communicated via facial expression, and why Hawking ultimately decided his landmark book "A Brief of History of Time" was written from the wrong perspective.
The 'designed' universe
During their first meeting at Cambridge University in 1998, Hawking wasted no time in bringing up the problem bothering him.
"The universe we observe appears designed," Hawking told Hertog, communicating via a clicker connected to a speech machine.
Hertog explained that "the laws of physics—the rules on which the universe runs—turn out to be just perfect for the universe to be habitable, for life to be possible."
This remarkable string of good luck stretches from the delicate balance that makes it possible for atoms to form molecules necessary for chemistry to the expansion of the universe itself, which allows for vast cosmic structures such as galaxies.
One "trendy" answer to this problem has been the multiverse, an idea that has recently become popular in the movie industry, Hertog said.
This theory explains away the seemingly designed nature of the universe by making it just one of countless others—most of which are "crap, lifeless, sterile", the 47-year-old added.
But Hawking realized the "great mire of paradoxes the multiverse was leading us into", arguing there must be a better explanation, Hertog said.
Outsider's perspective
A few years into their collaboration, "it began to sink in" that they were missing something fundamental, Hertog said.
The multiverse and even "A Brief History of Time" were "attempts to describe the creation and evolution of our universe from what Stephen would call a 'God's eye perspective'," Hertog said.
But because "we are within the universe" and not outside looking in, our theories cannot be decoupled from our perspective, he added.
Hawking had "a very wide range of facial expressions, ranging from extreme disagreement to extreme excitement", Hertog said.
"That was why (Hawking) said that 'A Brief History of Time' is written from the wrong perspective."
For the next 15 years, the pair used the oddities of quantum theory to develop a new theory of physics and cosmology from an "observer's perspective".
But by 2008, Hawking had lost the ability to use his clicker, becoming increasingly isolated from the world.
"I thought it was over," Hertog said.
Then the pair developed a "somewhat magical" level of non-verbal communication that allowed them to continue working, he said.
Positioned in front of Hawking, Hertog would ask questions and look into the physicist's eyes.
"He had a very wide range of facial expressions, ranging from extreme disagreement to extreme excitement," he said.
"It's impossible to disentangle" which parts of the final theory came from himself or Hawking, Hertog said, adding that many of the ideas had been developed between the pair over the years.
'One grand evolutionary process'
Their theory is focused on what happened in the first moments after the Big Bang.
Rather than an explosion that followed a pre-existing set of rules, they propose that the laws of physics evolved along with the universe.
This means that if you turn back the clock far enough, "the laws of physics themselves begin to simplify and disappear", Hertog said.
"Ultimately, even the dimension of time evaporates."
Under this theory, the laws of physics and time itself evolved in a way that resembles biological evolution—the title of Hertog's book is a reference to Darwin's "On the Origin of Species".
"What we're essentially saying is that (biology and physics) are two levels of one grand evolutionary process," Hertog said.
He acknowledged that it is difficult to prove this theory because the first years of the universe remain "hidden in the mist of the Big Bang".
One way to lift this veil could be by studying gravitational waves, ripples in the fabric of space time, while another could be via quantum holograms constructed on quantum computers, he said.
