Category: Science

This is counter-intuitive.

The universe and normal matter.

Frequently I look up at the night sky and ponder about so many things that I cannot understand. I wish I did but it is far too late now. But that doesn’t stop me from reading about the science and more. Here is a perfect example of that and I am delighted to be able to share it with you.

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Most normal matter in the universe isn’t found in planets, stars or galaxies – an astronomer explains where it’s distributed

Mysterious blasts of radio waves from across the universe called fast radio bursts help astronomers catalog matter. ESO/M. Kornmesser, CC BY-SA

Chris Impey, University of Arizona

If you look across space with a telescope, you’ll see countless galaxies, most of which host large central black holes, billions of stars and their attendant planets. The universe teems with huge, spectacular objects, and it might seem like these massive objects should hold most of the universe’s matter.

But the Big Bang theory predicts that about 5% of the universe’s contents should be atoms made of protons, neutrons and electrons. Most of those atoms cannot be found in stars and galaxies – a discrepancy that has puzzled astronomers.

If not in visible stars and galaxies, the most likely hiding place for the matter is in the dark space between galaxies. While space is often referred to as a vacuum, it isn’t completely empty. Individual particles and atoms are dispersed throughout the space between stars and galaxies, forming a dark, filamentary network called the “cosmic web.”

Throughout my career as an astronomer, I’ve studied this cosmic web, and I know how difficult it is to account for the matter spread throughout space.

In a study published in June 2025, a team of scientists used a unique radio technique to complete the census of normal matter in the universe.

The census of normal matter

The most obvious place to look for normal matter is in the form of stars. Gravity gathers stars together into galaxies, and astronomers can count galaxies throughout the observable universe.

The census comes to several hundred billion galaxies, each made of several hundred billion stars. The numbers are uncertain because many stars lurk outside of galaxies. That’s an estimated 1023 stars in the universe, or hundreds of times more than the number of sand grains on all of Earth’s beaches. There are an estimated 1082 atoms in the universe.

However, this prodigious number falls far short of accounting for all the matter predicted by the Big Bang. Careful accounting indicates that stars contain only 0.5% of the matter in the universe. Ten times more atoms are presumably floating freely in space. Just 0.03% of the matter is elements other than hydrogen and helium, including carbon and all the building blocks of life.

Looking between galaxies

The intergalactic medium – the space between galaxies – is near-total vacuum, with a density of one atom per cubic meter, or one atom every 35 cubic feet. That’s less than a billionth of a billionth of the density of air on Earth. Even at this very low density, this diffuse medium adds up to a lot of matter, given the enormous, 92-billion-light-year diameter of the universe.

The intergalactic medium is very hot, with a temperature of millions of degrees. That makes it difficult to observe except with X-ray telescopes, since very hot gas radiates out through the universe at very short X-ray wavelengths. X-ray telescopes have limited sensitivity because they are smaller than most optical telescopes.

Deploying a new tool

Astronomers recently used a new tool to solve this missing matter problem. Fast radio bursts are intense blasts of radio waves that can put out as much energy in a millisecond as the Sun puts out in three days. First discovered in 2007, scientists found that the bursts are caused by compact stellar remnants in distant galaxies. Their energy peters out as the bursts travel through space, and by the time that energy reaches the Earth, it is a thousand times weaker than a mobile phone signal would be if emitted on the Moon, then detected on Earth.

Research from early 2025 suggests the source of the bursts is the highly magnetic region around an ultra-compact neutron star. Neutron stars are incredibly dense remnants of massive stars that have collapsed under their own gravity after a supernova explosion. The particular type of neutron star that emits radio bursts is called a magnetar, with a magnetic field a thousand trillion times stronger than the Earth’s.

An illustration of a bright star with circular rings around it representing magnetic field lines
A magnetar is a rare type of neutron star with an extremely strong magnetic field. ESO/L. Calçada, CC BY-ND

Even though astronomers don’t fully understand fast radio bursts, they can use them to probe the spaces between galaxies. As the bursts travel through space, interactions with electrons in the hot intergalactic gas preferentially slow down longer wavelengths. The radio signal is spread out, analogous to the way a prism turns sunlight into a rainbow. Astronomers use the amount of spreading to calculate how much gas the burst has passed through on its way to Earth.

Puzzle solved

In the new study, published in June 2025, a team of astronomers from Caltech and the Harvard Center for Astrophysics studied 69 fast radio bursts using an array of 110 radio telescopes in California. The team found that 76% of the universe’s normal matter lies in the space between galaxies, with another 15% in galaxy halos – the area surrounding the visible stars in a galaxy – and the remaining 9% in stars and cold gas within galaxies.

The complete accounting of normal matter in the universe provides a strong affirmation of the Big Bang theory. The theory predicts the abundance of normal matter formed in the first few minutes of the universe, so by recovering the predicted 5%, the theory passes a critical test.

Several thousand fast radio bursts have already been observed, and an upcoming array of radio telescopes will likely increase the discovery rate to 10,000 per year. Such a large sample will let fast radio bursts become powerful tools for cosmology. Cosmology is the study of the size, shape and evolution of the universe. Radio bursts could go beyond counting atoms to mapping the three-dimensional structure of the cosmic web.

Pie chart of the universe

Scientists may now have the complete picture of where normal matter is distributed, but most of the universe is still made up of stuff they don’t fully understand.

The most abundant ingredients in the universe are dark matter and dark energy, both of which are poorly understood. Dark energy is causing the accelerating expansion of the universe, and dark matter is the invisible glue that holds galaxies and the universe together.

A pie chart showing the composition of the universe. The largest proportion is dark energy, at 68%, while dark matter makes up 27% and normal matter 5%. The rest is neutrinos, free hydrogen and helium and heavy elements.
Despite physicists not knowing much about it, dark matter makes up around 27% of the universe. Visual Capitalist/Science Photo Library via Getty Images

Dark matter is probably a previously unstudied type of fundamental particle that is not part of the standard model of particle physics. Physicists haven’t been able to detect this novel particle yet, but we know it exists because, according to general relativity, mass bends light, and far more gravitational lensing is seen than can be explained by visible matter. With gravitational lensing, a cluster of galaxies bends and magnifies light in a way that’s analogous to an optical lens. Dark matter outweighs conventional matter by more than a factor of five.

One mystery may be solved, but a larger mystery remains. While dark matter is still enigmatic, we now know a lot about the normal atoms making up us as humans, and the world around us.

Chris Impey, University Distinguished Professor of Astronomy, University of Arizona

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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The details are incredible. Take for example that three-quarters of the matter out there is found outside the galaxies. Or that there are more stars in the universe than all of the sand grains on Planet Earth.

Just amazing!

‘Tolly’ finds something really special

I’m indebted to George Monbiot for this article, and ‘Tolly’ as a nickname for Iain Tolhurst.

Many articles from people that I follow online pass through my ‘inbox’.

But there was something special about a recent article by George Monbiot that was published in the Guardian on December 5th and I have great pleasure in republishing it here, with George’s permission.

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Shaking It Up

Posted on 7th December 2025

A eureka moment in the pub could help transform our understanding of the ground beneath our feet.

By George Monbiot, published in the Guardian 5th December 2025

It felt like walking up a mountain during a temperature inversion. You struggle through fog so dense you can scarcely see where you’re going. Suddenly, you break through the top of the cloud, and the world is laid out before you. It was that rare and remarkable thing: a eureka moment.
For the past three years, I’d been struggling with a big and frustrating problem. In researching my book Regenesis, I’d been working closely with Iain Tolhurst (Tolly), a pioneering farmer who had pulled off something extraordinary. Almost everywhere, high-yield farming means major environmental harm, due to the amount of fertiliser, pesticides and (sometimes) irrigation water and deep ploughing required. Most farms with apparently small environmental impacts produce low yields. This, in reality, means high impacts, as more land is needed to produce a given amount of food. But Tolly has found the holy grail of agriculture: high and rising yields with minimal environmental harm.

He uses no fertiliser, no animal manure and no pesticides. His techniques, the result of decades of experiment and observation, appear to enrich the crucial relationships between crops and microbes in the soil, through which soil nutrients must pass. It seems that Tolly has, in effect, “trained” his soil bacteria to release nutrients when his crops require them (a process called mineralisation), and lock them up when his crops aren’t growing (immobilisation), ensuring they don’t leach from the soil.

So why the frustration? Well, Tolly has inspired many other growers to attempt the same techniques. Some have succeeded, with excellent results. Others have not. And no one can work out why. It’s likely to have something to do with soil properties. But what?

Not for the first time, I had stumbled into a knowledge gap so wide that humanity could fall through it. Soil is a fantastically complex biological structure, like a coral reef, built and sustained by the creatures that inhabit it. It supplies 99% of our calories. Yet we know less about it than any other identified ecosystem. It’s almost a black box.

Many brilliant scientists have devoted their lives to its study. But there are major barriers. Most soil properties cannot be seen without digging, and if you dig a hole, you damage the structures you’re trying to investigate. As a result, studying even basic properties is cumbersome, time-consuming and either very expensive or simply impossible at scale. To measure the volume of soil in a field, for example, you need to take hundreds of core samples. But as soil depths can vary greatly from one metre to the next, your figure relies on extrapolation. This makes it very hard to tell whether you’re losing soil or gaining it. Measuring bulk density (the amount of soil in a given volume, which shows how compacted it might be), or connected porosity (the tiny catacombs created by lifeforms, a crucial measure of soil health), or soil carbon – at scale – is even harder.

So farmers must guess. Partly because they cannot see exactly what the soil needs, many of their inputs – fertilisers, irrigation, deep ploughing – are wasted. Roughly two-thirds of the nitrogen fertiliser they apply, and between 50% and 80% of their phosphorus, is lost. These lost minerals cause algal blooms in rivers, dead zones at sea, costs for water users and global heating. Huge amounts of irrigation water are also wasted. Farmers sometimes “subsoil” their fields – ploughing that is deep and damaging – because they suspect compaction. The suspicion is often wrong.

Our lack of knowledge also inhibits the development of a new agriculture, which may, as Tolly has done, allow farmers to replace chemical augmentation with biological enhancement.

So when I came to write the book, I made a statement so vague that it reads like an admission of defeat: we needed to spend heavily on “an advanced science of the soil”, and use it to deliver a “greener revolution”. While we know almost nothing about the surface of our own planet, billions are spent on the Mars Rover programme, exploring the barren regolith there. What we needed, I argued, is an Earth Rover programme, mapping the world’s agricultural soils at much finer resolution.

I might as well have written “something must be done!” The necessary technologies simply did not exist. I sank into a stygian gloom.

At the same time, Tarje Nissen-Meyer, then a professor of geophysics at the University of Oxford, was grappling with a different challenge. Seismology is the study of waves passing through a solid medium. Thanks to billions from the oil and gas industry, it has become highly sophisticated. Tarje wanted to use this powerful tool for the opposite purpose – ecological improvement. Already, with colleagues, he had deployed seismology to study elephant behaviour in Kenya. Not only was it highly effective, but his team also discovered it could identify animal species walking through the savannah by their signature footfall.

By luck we were both attached, in different ways, to Wolfson College, Oxford, where we met in February 2022. I saw immediately that he was a thoughtful man – a visionary. I suggested a pint in The Magdalen Arms.

I explained my problem, and we talked about the limits of existing technologies. Was seismology being used to study soil, I asked. He’d never heard of it. “I guess it’s not a suitable technology then?” No, he told me, “soil should be a good medium for seismology. In fact, we need to filter out the soil noise when we look at the rocks.” “So if it’s noise, it could be signal?” “Definitely.”

We stared at each other. Time seemed to stall. Could this really be true?

Over the next three days, Tarje conducted a literature search. Nothing came up. I wrote to Prof Simon Jeffery, an eminent soil scientist at Harper Adams University, whose advice I’d found invaluable when researching the book. I set up a Zoom call. He would surely explain that we were barking up the wrong tree.

Simon is usually a reserved man. But when he had finished questioning Tarje, he became quite animated. “All my life I’ve wanted to ‘see’ into the soil,” he said. “Maybe now we can.” I was introduced to a brilliant operations specialist, Katie Bradford, who helped us build an organisation. We set up a non-profit called the Earth Rover Program, to develop what we call “soilsmology”; to build open-source hardware and software cheap enough to be of use to farmers everywhere; and to create, with farmers, a global, self-improving database. This, we hope, might one day incorporate every soil ecosystem: a kind of Human Genome Project for the soil.

We later found that some scientists had in fact sought to apply seismology to soil, but it had not been developed into a programme, partly because the approaches used were not easily scalable.

My role was mostly fixer, finding money and other help. We received $4m (£3m) in start-up money from the Bezos Earth Fund. This may cause some discomfort, but our experience has been entirely positive: the fund has helped us do exactly what we want. We also got a lot of pro-bono help from the law firm Hogan Lovells.

Tarje, now at the University of Exeter, and Simon began assembling their teams. They would need to develop an ultra-high-frequency variant of seismology. A big obstacle was cost. In 2022, suitable sensors cost $10,000 (£7,500) apiece. They managed to repurpose other kit: Tarje found that a geophone developed by a Slovakian experimental music outfitworked just as well, and cost only $100. Now one of our scientists, Jiayao Meng, is developing a sensor for about $10. In time, we should be able to use the accelerometers in mobile phones, reducing the cost to zero. As for generating seismic waves, we get all the signal we need by hitting a small metal plate with a welder’s hammer.

On its first deployment, our team measured the volume of a peat bog that had been studied by scientists for 50 years. After 45 minutes in the field, they produced a preliminary estimate suggesting that previous measurements were out by 20%. Instead of extrapolating the peat depth from point samples, they could see the wavy line where the peat met the subsoil. The implications for estimating carbon stocks are enormous.

We’ve also been able to measure bulk density at a very fine scale; to track soil moisture (as part of a wider team); to start building the AI and machine learning tools we need; and to see the varying impacts of different agricultural crops and treatments. Next we’ll work on measuring connected porosity, soil texture and soil carbon; scaling up to the hectare level and beyond; and on testing the use of phones as seismometers. We now have further funding, from the UBS Optimus Foundation, hubs on three continents and a big international team.

Eventually, we hope, any farmer anywhere, rich or poor, will be able to get an almost instant readout from their soil. As more people use the tools, building the global database, we hope these readouts will translate into immediate useful advice. The tools should also revolutionise soil protection: the EU has issued a soil-monitoring law, but how can it be implemented? Farmers are paid for their contributions “to improve soil health and soil resilience”, but what this means in practice is ticking a box on a subsidy form: there’s no sensible way of checking.

We’re not replacing the great work of other soil scientists but, developing our methods alongside theirs, we believe we can fill part of the massive knowledge gap. As one of the farmers we’re working with, Roddy Hall, remarks, the Earth Rover Program could “take the guesswork out of farming”. One day it might help everyone arrive at that happy point: high yields with low impacts. Seismology promises to shake things up.

http://www.monbiot.com

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George Monbiot puts his finger precisely on the point of his article: “While we know almost nothing about the surface of our own planet, billions are spent on the Mars Rover programme.“

That magical night sky

Or more to the point of this article: Dark Matter.

Along with huge numbers of other people, I have long been interested in the Universe. Thus this article from The Conversation seemed a good one to share with you.

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When darkness shines: How dark stars could illuminate the early universe

NASA’s James Webb Space Telescope has spotted some potential dark star candidates. NASA, ESA, CSA, and STScI

Alexey A. Petrov, University of South Carolina

Scientists working with the James Webb Space Telescope discovered three unusual astronomical objects in early 2025, which may be examples of dark stars. The concept of dark stars has existed for some time and could alter scientists’ understanding of how ordinary stars form. However, their name is somewhat misleading.

“Dark stars” is one of those unfortunate names that, on the surface, does not accurately describe the objects it represents. Dark stars are not exactly stars, and they are certainly not dark.

Still, the name captures the essence of this phenomenon. The “dark” in the name refers not to how bright these objects are, but to the process that makes them shine — driven by a mysterious substance called dark matter. The sheer size of these objects makes it difficult to classify them as stars.

As a physicist, I’ve been fascinated by dark matter, and I’ve been trying to find a way to see its traces using particle accelerators. I’m curious whether dark stars could provide an alternative method to find dark matter.

What makes dark matter dark?

Dark matter, which makes up approximately 27% of the universe but cannot be directly observed, is a key idea behind the phenomenon of dark stars. Astrophysicists have studied this mysterious substance for nearly a century, yet we haven’t seen any direct evidence of it besides its gravitational effects. So, what makes dark matter dark?

A pie chart showing the composition of the universe. The largest proportion is 'dark energy,' at 68%, while dark matter makes up 27% and normal matter 5%. The rest is neutrinos, free hydrogen and helium and heavy elements.
Despite physicists not knowing much about it, dark matter makes up around 27% of the universe. Visual Capitalist/Science Photo Library via Getty Images

Humans primarily observe the universe by detecting electromagnetic waves emitted by or reflected off various objects. For instance, the Moon is visible to the naked eye because it reflects sunlight. Atoms on the Moon’s surface absorb photons – the particles of light – sent from the Sun, causing electrons within atoms to move and send some of that light toward us.

More advanced telescopes detect electromagnetic waves beyond the visible spectrum, such as ultraviolet, infrared or radio waves. They use the same principle: Electrically charged components of atoms react to these electromagnetic waves. But how can they detect a substance – dark matter – that not only has no electric charge but also has no electrically charged components?

Although scientists don’t know the exact nature of dark matter, many models suggest that it is made up of electrically neutral particles – those without an electric charge. This trait makes it impossible to observe dark matter in the same way that we observe ordinary matter.

Dark matter is thought to be made of particles that are their own antiparticles. Antiparticles are the “mirror” versions of particles. They have the same mass but opposite electric charge and other properties. When a particle encounters its antiparticle, the two annihilate each other in a burst of energy.

If dark matter particles are their own antiparticles, they would annihilate upon colliding with each other, potentially releasing large amounts of energy. Scientists predict that this process plays a key role in the formation of dark stars, as long as the density of dark matter particles inside these stars is sufficiently high. The dark matter density determines how often dark matter particles encounter, and annihilate, each other. If the dark matter density inside dark stars is high, they would annihilate frequently.

What makes a dark star shine?

The concept of dark stars stems from a fundamental yet unresolved question in astrophysics: How do stars form? In the widely accepted view, clouds of primordial hydrogen and helium — the chemical elements formed in the first minutes after the Big Bang, approximately 13.8 billion years ago — collapsed under gravity. They heated up and initiated nuclear fusion, which formed heavier elements from the hydrogen and helium. This process led to the formation of the first generation of stars.

Two bright clouds of gas condensing around a small central region
Stars form when clouds of dust collapse inward and condense around a small, bright, dense core. NASA, ESA, CSA, and STScI, J. DePasquale (STScI), CC BY-ND

In the standard view of star formation, dark matter is seen as a passive element that merely exerts a gravitational pull on everything around it, including primordial hydrogen and helium. But what if dark matter had a more active role in the process? That’s exactly the question a group of astrophysicists raised in 2008.

In the dense environment of the early universe, dark matter particles would collide with, and annihilate, each other, releasing energy in the process. This energy could heat the hydrogen and helium gas, preventing it from further collapse and delaying, or even preventing, the typical ignition of nuclear fusion.

The outcome would be a starlike object — but one powered by dark matter heating instead of fusion. Unlike regular stars, these dark stars might live much longer because they would continue to shine as long as they attracted dark matter. This trait would make them distinct from ordinary stars, as their cooler temperature would result in lower emissions of various particles.

Can we observe dark stars?

Several unique characteristics help astronomers identify potential dark stars. First, these objects must be very old. As the universe expands, the frequency of light coming from objects far away from Earth decreases, shifting toward the infrared end of the electromagnetic spectrum, meaning it gets “redshifted.” The oldest objects appear the most redshifted to observers.

Since dark stars form from primordial hydrogen and helium, they are expected to contain little to no heavier elements, such as oxygen. They would be very large and cooler on the surface, yet highly luminous because their size — and the surface area emitting light — compensates for their lower surface brightness.

They are also expected to be enormous, with radii of about tens of astronomical units — a cosmic distance measurement equal to the average distance between Earth and the Sun. Some supermassive dark stars are theorized to reach masses of roughly 10,000 to 10 million times that of the Sun, depending on how much dark matter and hydrogen or helium gas they can accumulate during their growth.

So, have astronomers observed dark stars? Possibly. Data from the James Webb Space Telescope has revealed some very high-redshift objects that seem brighter — and possibly more massive — than what scientists expect of typical early galaxies or stars. These results have led some researchers to propose that dark stars might explain these objects.

Artist's impression of the James Webb telescope, which has a hexagonal mirror made up of smaller hexagons, and sits on a rhombus-shaped spacecraft.
The James Webb Space Telescope, shown in this illustration, detects light coming from objects in the universe. Northrup Grumman/NASA

In particular, a recent study analyzing James Webb Space Telescope data identified three candidates consistent with supermassive dark star models. Researchers looked at how much helium these objects contained to identify them. Since it is dark matter annihilation that heats up those dark stars, rather than nuclear fusion turning helium into heavier elements, dark stars should have more helium.

The researchers highlight that one of these objects indeed exhibited a potential “smoking gun” helium absorption signature: a far higher helium abundance than one would expect in typical early galaxies.

Dark stars may explain early black holes

What happens when a dark star runs out of dark matter? It depends on the size of the dark star. For the lightest dark stars, the depletion of dark matter would mean gravity compresses the remaining hydrogen, igniting nuclear fusion. In this case, the dark star would eventually become an ordinary star, so some stars may have begun as dark stars.

Supermassive dark stars are even more intriguing. At the end of their lifespan, a dead supermassive dark star would collapse directly into a black hole. This black hole could start the formation of a supermassive black hole, like the kind astronomers observe at the centers of galaxies, including our own Milky Way.

Dark stars might also explain how supermassive black holes formed in the early universe. They could shed light on some unique black holes observed by astronomers. For example, a black hole in the galaxy UHZ-1 has a mass approaching 10 million solar masses, and is very old – it formed just 500 million years after the Big Bang. Traditional models struggle to explain how such massive black holes could form so quickly.

The idea of dark stars is not universally accepted. These dark star candidates might still turn out just to be unusual galaxies. Some astrophysicists argue that matter accretion — a process in which massive objects pull in surrounding matter — alone can produce massive stars, and that studies using observations from the James Webb telescope cannot distinguish between massive ordinary stars and less dense, cooler dark stars.

Researchers emphasize that they will need more observational data and theoretical advancements to solve this mystery.

Alexey A. Petrov, Professor of physics and astronomy, University of South Carolina

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Alexey Petrov says at the end of the article that more observations are required before we humans know all the answers. I have no doubt that in time we will have the answers.

Cambridge University and our brains.

Scientists have identified five ages of the human brain.

“Neuroscientists at the University of Cambridge have identified five “major epochs” of brain structure over the course of a human life, as our brains rewire to support different ways of thinking while we grow, mature, and ultimately decline.”

So wrote Fred Lewsey. Fred is the Communications Manager (Research) and is Responsible for: School of the Humanities and Social Sciences. (And I took this from this site.) He went on to report that: Four major turning points around ages nine, 32, 66 and 83 create five broad eras of neural wiring over the average human lifespan.

Being in my early 80’s I was most interested in that last turning point. This is the information about that era:

The last turning point comes around age 83, and the final brain structure epoch is entered. While data is limited for this era, the defining feature is a shift from global to local, as whole brain connectivity declines even further, with increased reliance on certain regions.     

“Looking back, many of us feel our lives have been characterised by different phases. It turns out that brains also go through these eras,” added senior author Prof Duncan Astle, Professor of Neuroinformatics at Cambridge.

“Many neurodevelopmental, mental health and neurological conditions are linked to the way the brain is wired. Indeed, differences in brain wiring predict difficulties with attention, language, memory, and a whole host of different behaviours”

“Understanding that the brain’s structural journey is not a question of steady progression, but rather one of a few major turning points, will help us identify when and how its wiring is vulnerable to disruption.”

The research was supported by the Medical Research Council, Gates Foundation and Templeton World Charitable Foundation. The full report may be read here: https://www.newscientist.com/article/2505656-your-brain-undergoes-four-dramatic-periods-of-change-from-age-0-to-90

Finally, here is an image of this amazing organ that we humans have.

Photo by BUDDHI Kumar SHRESTHA on Unsplash

The DNA of dogs.

What is revealed in most dogs’ genes.

On November 24th this year, The Conversation published an article that spoke of the ancient closeness, as in genetically, of wolves and dogs.

I share it with you. It is a fascinating read.

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Thousands of genomes reveal the wild wolf genes in most dogs’ DNA.

Modern wolves and dogs both descend from an ancient wolf population that lived alongside woolly mammoths and cave bears. Iza Lyson/500px Prime via Getty Images

Audrey T. Lin, Smithsonian Institution and Logan Kistler, Smithsonian Institution

Dogs were the first of any species that people domesticated, and they have been a constant part of human life for millennia. Domesticated species are the plants and animals that have evolved to live alongside humans, providing nearly all of our food and numerous other benefits. Dogs provide protection, hunting assistance, companionship, transportation and even wool for weaving blankets.

Dogs evolved from gray wolves, but scientists debate exactly where, when and how many times dogs were domesticated. Ancient DNA evidence suggests that domestication happened twice, in eastern and western Eurasia, before the groups eventually mixed. That blended population was the ancestor of all dogs living today.

Molecular clock analysis of the DNA from hundreds of modern and ancient dogs suggests they were domesticated between around 20,000 and 22,000 years ago, when large ice sheets covered much of Eurasia and North America. The first dog identified in the archaeological record is a 14,000-year-old pup found in Bonn-Oberkassel, Germany, but it can be difficult to tell based on bones whether an animal was an early domestic dog or a wild wolf.

Despite the shared history of dogs and wolves, scientists have long thought these two species rarely mated and gave birth to hybrid offspring. As an evolutionary biologist and a molecular anthropologist who study domestic plants and animals, we wanted to take a new look at whether dog-wolf hybridization has really been all that uncommon.

Little interbreeding in the wild

Dogs are not exactly descended from modern wolves. Rather, dogs and wolves living today both derive from a shared ancient wolf population that lived alongside woolly mammoths and cave bears.

In most domesticated species, there are often clear, documented patterns of gene flow between the animals that live alongside humans and their wild counterparts. Where wild and domesticated animals’ habitats overlap, they can breed with each other to produce hybrid offspring. In these cases, the genes from wild animals are folded into the genetic variation of the domesticated population.

For example, pigs were domesticated in the Near East over 10,000 years ago. But when early farmers brought them to Europe, they hybridized so frequently with local wild boar that almost all of their Near Eastern DNA was replaced. Similar patterns can be seen in the endangered wild Anatolian and Cypriot mouflon that researchers have found to have high proportions of domestic sheep DNA in their genomes. It’s more common than not to find evidence of wild and domesticated animals interbreeding through time and sharing genetic material.

That wolves and dogs wouldn’t show that typical pattern is surprising, since they live in overlapping ranges and can freely interbreed.

Dog and wolf behavior are completely different, though, with wolves generally organized around a family pack structure and dogs reliant on humans. When hybridization does occur, it tends to be when human activities – such as habitat encroachment and hunting – disrupt pack dynamics, leading female wolves to strike out on their own and breed with male dogs. People intentionally bred a few “wolf dog” hybrid types in the 20th century, but these are considered the exception.

a wolfish looking dog lies on the ground behind a metal fence
Luna Belle, a resident of the Wolf Sanctuary of Pennsylvania, which is home to both wolves and wolf dogs. Audrey Lin.

Tiny but detectable wolf ancestry

To investigate how much gene flow there really has been between dogs and wolves after domestication, we analyzed 2,693 previously published genomes, making use of massive publicly available datasets.

These included 146 ancient dogs and wolves covering about 100,000 years. We also looked at 1,872 modern dogs, including golden retrievers, Chihuahuas, malamutes, basenjis and other well-known breeds, plus more unusual breeds from around the world such as the Caucasian ovcharka and Swedish vallhund.

Finally, we included genomes from about 300 “village dogs.” These are not pets but are free-living animals that are dependent on their close association with human environments.

We traced the evolutionary histories of all of these canids by looking at maternal lineages via their mitochondrial genomes and paternal lineages via their Y chromosomes. We used highly sensitive computational methods to dive into the dogs’ and wolves’ nuclear genomes – that is, the genetic material contained in their cells’ nuclei.

We found the presence of wild wolf genes in most dog genomes and the presence of dog genes in about half of wild wolf genomes. The sign of the wolf was small but it was there, in the form of tiny, almost imperceptible chunks of continuous wolf DNA in dogs’ chromosomes. About two-thirds of breed dogs in our sample had wolf genes from crossbreeding that took place roughly 800 generations ago, on average.

While our results showed that larger, working dogs – such as sled dogs and large guardian dogs that protect livestock – generally have more wolf ancestry, the patterns aren’t universal. Some massive breeds such as the St. Bernard completely lack wolf DNA, but the tiny Chihuahua retains detectable wolf ancestry at 0.2% of its genome. Terriers and scent hounds typically fall at the low end of the spectrum for wolf genes.

a dog curled up on the sidewalk in a town
A street – or free-ranging – dog in Tbilisi, Georgia. Alexkom000/Wikimedia Commons, CC BY

We were surprised that every single village dog we tested had pieces of wolf DNA in their genomes. Why would this be the case? Village dogs are free-living animals that make up about half the world’s dogs. Their lives can be tough, with short life expectancy and high infant mortality. Village dogs are also associated with pathogenic diseases, including rabies and canine distemper, making them a public health concern.

More often than predicted by chance, the stretches of wolf DNA we found in village dog genomes contained genes related to olfactory receptors. We imagine that olfactory abilities influenced by wolf genes may have helped these free-living dogs survive in harsh, volatile environments.

The intertwining of dogs and wolves

Because dogs evolved from wolves, all of dogs’ DNA is originally wolf DNA. So when we’re talking about the small pieces of wolf DNA in dog genomes, we’re not referring to that original wolf gene pool that’s been kicking around over the past 20,000 years, but rather evidence for dogs and wolves continuing to interbreed much later in time.

A wolf-dog hybrid with one of each kind of parent would carry 50% dog and 50% wolf DNA. If that hybrid then lived and mated with dogs, its offspring would be 25% wolf, and so on, until we see only small snippets of wolf DNA present.

The situation is similar to one in human genomes: Neanderthals and humans share a common ancestor around half a million years ago. However, Neanderthals and our species, Homo sapiens, also overlapped and interbred in Eurasia as recently as a few thousand generations ago, shortly before Neanderthals disappeared. Scientists can spot the small pieces of Neanderthal DNA in most living humans in the same way we can see wolf genes within most dogs.

two small tan dogs walking on pavement on a double lead leash
Even tiny Chihuahuas contain a little wolf within their doggy DNA. Westend61 via Getty Images

Our study updates the previously held belief that hybridization between dogs and wolves is rare; interactions between these two species do have visible genetic traces. Hybridization with free-roaming dogs is considered a threat to conservation efforts of endangered wolves, including Iberian, Italian and Himalayan wolves. However, there also is evidence that dog-wolf mixing might confer genetic advantages to wolves as they adapt to environments that are increasingly shaped by humans.

Though dogs evolved as human companions, wolves have served as their genetic lifeline. When dogs encountered evolutionary challenges such as how to survive harsh climates, scavenge for food in the streets or guard livestock, it appears they’ve been able to tap into wolf ancestry as part of their evolutionary survival kit.

Audrey T. Lin, Research Associate in Anthropology, Smithsonian Institution and Logan Kistler, Curator of Archaeobotany and Archaeogenomics, National Museum of Natural History, Smithsonian Institution

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Well thanks to Audrey Lin and Logan Kistler for this very interesting study. So even modern dogs have visible traces of wolf in their DNA. It is yet another example of the ability of modern science to discover facts that were unknown a few decades ago.

A worldwide myth.

An incredible fact, as in the truth, that almost nobody will accept.

Until the 22nd November, 2025, that is last Saturday, I believed this lie. A lie that spoke of the dangers, the hazards, the imminent end of the world as I believed it; as in Climate Change!

Very few of you will change your minds, of that I’m sure.

Nonetheless, I am going to republish a long article that was sent to me by my buddy, Dan Gomez.

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Latest Science Further Exposes Lies About Rising Seas

By Vijay Jayaraj

It’s all too predictable: A jet-setting celebrity or politician wades ceremoniously into hip-deep surf for a carefully choreographed photo op, while proclaiming that human-driven sea-level rise will soon swallow an island nation. Of course, the water is deeper than the video’s pseudoscience, which is as shallow as the theatrics.

The scientific truth is simple: Sea levels are rising, but the rate of rise has not accelerated. A new peer-reviewed study confirms what many other studies have already shown – that the steady rise of oceans is a centuries-long process, not a runaway crisis triggered by modern emissions of carbon dioxide (CO2).

For the past 12,000 years, during our current warm epoch known as the Holocene, sea levels have risen and fallen dramatically. For instance, during the 600-year Little Ice Age, which ended in the mid-19th century, sea levels dropped quite significantly.

The natural warming that began in the late 1600s got to a point around 1800 where loss of glacial ice in the summer began to exceed winter accumulation and glaciers began to shrink and seas to rise. By 1850, full-on glacial retreat was underway.

Thus, the current period of gradual sea-level increase began between 1800-1860, preceding any significant anthropogenic CO2 emissions by many decades. The U.S. Department of Energy’s 2025 critical review on carbon dioxide and climate change confirms this historical perspective.

“There is no good, sufficient or convincing evidence that global sea level rise is accelerating –there is only hypothesis and speculation. Computation is not evidence and unless the results can be practically viewed and measured in the physical world, such results must not be presented as such,” notes Kip Hansen, researcher and former U.S. Coast Guard captain.

New Study Confirms No Crisis

While activists speak of “global sea-level rise,” the ocean’s surface does not behave like water in a bathtub. Regional currents, land movements, and local hydrology all influence relative sea level. This is why local tide gauge data is important. As Hansen warns, “Only actually measured, validated raw data can be trusted. … You have to understand exactly what’s been measured and how.”

In addition, local tide-gauge data cannot be extrapolated to represent global sea level. This is because the geographic coverage of suitable locations for gauges is often poor, with the majority concentrated in the Northern Hemisphere. Latin America and Africa are severely under-represented in the global dataset.  Hansen says, “The global tide gauge record is quantitatively problematic, but individual records can be shown as qualitative evidence for a lack of sea-level rise acceleration.”

A new 2025 study provides confirmation. Published in the Journal of Marine Science and Engineering, the study systematically dismantles the narrative of accelerating sea-level rise. It analyzed empirically derived long-term rates from datasets of sufficient length – at least 60 years – and incorporated long-term tide signals from suitable locations.

The startling conclusion: Approximately 95% of monitoring locations show no statistically significant acceleration of sea-level rise. It was found that the steady rate of sea-level rise – averaging around 1 to 2 millimeters per year globally – mirrors patterns observed over the past 150 years.

The study suggests that projections by the Intergovernmental Panel on Climate Change (IPCC), which often predicts rates as high as 3 to 4 millimeters per year by 2100, overestimate the annual rise by approximately 2 millimeters.

This discrepancy is not trivial. It translates into billions of dollars in misguided infrastructure investments and adaptation policies, which assume a far worse scenario than what the data support. Because we now know that local, non-climatic phenomena are a plausible cause of the accelerated sea level rise measured locally.

Rather than pursuing economically destructive initiatives to reduce greenhouse gas emissions on the basis of questionable projections and erroneous climate science, money and time should be invested in supporting coastal communities with accurate data for practical planning to adapt to local sea level rise.

Successful adaptation strategies have existed for centuries in regions prone to flooding and sea-level variations. The Netherlands is an excellent example of how engineering solutions can protect coastal populations even living below sea level.

Rising seas are real but not a crisis. What we have is a manageable, predictable phenomenon to which societies have adapted for centuries. To inflate it into an existential threat is to mislead, misallocate, and ultimately harm the communities that policymakers claim to protect.

This commentary was first published by PJ Media on September 10, 2025.

Vijay Jayaraj is a Science and Research Associate at the CO₂ Coalition, Fairfax, Virginia. He holds an M.S. in environmental sciences from the University of East Anglia and a postgraduate degree in energy management from Robert Gordon University, both in the U.K., and a bachelor’s in engineering from Anna University, India.

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I shall be returning to this important topic soon. Probably by republishing that 2025 Study referred to in the above article.

I hope that you read this post.

Thank you, Dan.

We humans are still evolving.

An article in The Conversation caught my eye.

We must never forget that evolution is always happening.

So without any more from me here is that article.

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If evolution is real, then why isn’t it happening now? An anthropologist explains that humans actually are still evolving

Inuit people such as these Greenlanders have evolved to be able to eat fatty foods with a low risk of getting heart disease. Olivier Morin/AFP via Getty Images

Michael A. Little, Binghamton University, State University of New York

If evolution is real, then why is it not happening now? – Dee, Memphis, Tennessee

Many people believe that we humans have conquered nature through the wonders of civilization and technology. Some also believe that because we are different from other creatures, we have complete control over our destiny and have no need to evolve. Even though lots of people believe this, it’s not true.

Like other living creatures, humans have been shaped by evolution. Over time, we have developed – and continue to develop – the traits that help us survive and flourish in the environments where we live.

I’m an anthropologist. I study how humans adapt to different environments. Adaptation is an important part of evolution. Adaptations are traits that give someone an advantage in their environment. People with those traits are more likely to survive and pass those traits on to their children. Over many generations, those traits become widespread in the population.

The role of culture

We humans have two hands that help us skillfully use tools and other objects. We are able to walk and run on two legs, which frees our hands for these skilled tasks. And we have large brains that let us reason, create ideas and live successfully with other people in social groups.

All of these traits have helped humans develop culture. Culture includes all of our ideas and beliefs and our abilities to plan and think about the present and the future. It also includes our ability to change our environment, for example by making tools and growing food.

Although we humans have changed our environment in many ways during the past few thousand years, we are still changed by evolution. We have not stopped evolving, but we are evolving right now in different ways than our ancient ancestors. Our environments are often changed by our culture.

We usually think of an environment as the weather, plants and animals in a place. But environments include the foods we eat and the infectious diseases we are exposed to.

A very important part of the environment is the climate and what kinds of conditions we can live in. Our culture helps us change our exposure to the climate. For example, we build houses and put furnaces and air conditioners in them. But culture doesn’t fully protect us from extremes of heat, cold and the sun’s rays.

a man runs after one of several goats in a dry, dusty landscape
The Turkana people in Kenya have evolved to survive with less water than other people, which helps them live in a desert environment. Tony Karumba/AFP via Getty Images

Here are some examples of how humans have evolved over the past 10,000 years and how we are continuing to evolve today.

The power of the sun’s rays

While the sun’s rays are important for life on our planet, ultraviolet rays can damage human skin. Those of us with pale skin are in danger of serious sunburn and equally dangerous kinds of skin cancer. In contrast, those of us with a lot of skin pigment, called melanin, have some protection against damaging ultraviolet rays from sunshine.

People in the tropics with dark skin are more likely to thrive under frequent bright sunlight. Yet, when ancient humans moved to cloudy, cooler places, the dark skin was not needed. Dark skin in cloudy places blocked the production of vitamin D in the skin, which is necessary for normal bone growth in children and adults.

The amount of melanin pigment in our skin is controlled by our genes. So in this way, human evolution is driven by the environment – sunny or cloudy – in different parts of the world.

The food that we eat

Ten thousand years ago, our human ancestors began to tame or domesticate animals such as cattle and goats to eat their meat. Then about 2,000 years later, they learned how to milk cows and goats for this rich food. Unfortunately, like most other mammals at that time, human adults back then could not digest milk without feeling ill. Yet a few people were able to digest milk because they had genes that let them do so.

Milk was such an important source of food in these societies that the people who could digest milk were better able to survive and have many children. So the genes that allowed them to digest milk increased in the population until nearly everyone could drink milk as adults.

This process, which occurred and spread thousands of years ago, is an example of what is called cultural and biological co-evolution. It was the cultural practice of milking animals that led to these genetic or biological changes.

Other people, such as the Inuit in Greenland, have genes that enable them to digest fats without suffering from heart diseases. The Turkana people herd livestock in Kenya in a very dry part of Africa. They have a gene that allows them to go for long periods without drinking much water. This practice would cause kidney damage in other people because the kidney regulates water in your body.

These examples show how the remarkable diversity of foods that people eat around the world can affect evolution.

gray scale microscope image of numerous blobs
These bacteria caused a devastating pandemic nearly 700 years ago that led humans to evolve resistance to them.
Image Point FR/NIH/NIAID/BSIP/Universal Images Group via Getty Images

Diseases that threaten us

Like all living creatures, humans have been exposed to many infectious diseases. During the 14th century a deadly disease called the bubonic plague struck and spread rapidly throughout Europe and Asia. It killed about one-third of the population in Europe. Many of those who survived had a specific gene that gave them resistance against the disease. Those people and their descendants were better able to survive epidemics that followed for several centuries.

Some diseases have struck quite recently. COVID-19, for instance, swept the globe in 2020. Vaccinations saved many lives. Some people have a natural resistance to the virus based on their genes. It may be that evolution increases this resistance in the population and helps humans fight future virus epidemics.

As human beings, we are exposed to a variety of changing environments. And so evolution in many human populations continues across generations, including right now.

Michael A. Little, Distinguished Professor Emeritus of Anthropology, Binghamton University, State University of New York

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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This was published for the Curious Kids section of The Conversation.

However, I believe this is relevant for those adults as well who are interested in the subject. I’m in my 80’s and find this deeply interesting.

Picture Parade Four Hundred and Ninety-Seven

Some photos of The Northern Lights.

EarthSky’s Kelly Kizer Whitt captured the northern lights from near Madison, Wisconsin, on November 11, 2025. Kelly wrote: “An amazing night of aurora. In front of the red curtains we had bright green active blobs. One of the better displays I’ve seen.” Thank you, Kelly!

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Ross Stone in Big Pine, California, captured this stunning view on November 11, 2025, and wrote: “The NRAO radio telescope in Owens Valley and the beautiful red aurora in the November sky. This was awesome, and the sky was so bright.” Thank you, Ross!

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EarthSky’s Marcy Curran in Cheyenne, Wyoming, captured a beautiful display of auroras on November 11, 2025. Marcy wrote: “Aurora put on quite a show from Wyoming tonight. Lots of reds and green easily visible to the eye. We live in a semi-rural spot.” Thank you, Marcy!

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Darrell Reese could see the aurora on November 11, 2025, from Ohio! Thank you for sharing your photo, Darrell.

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Ruth Goodwin-Hager in Eureka Springs, Arkansas, shared this image from November 11, 2025, and wrote: “I banged on my neighbors’ doors and recruited others to come outside and see the fabulous lights. It’s been 30 years since I’ve seen northern lights from my backyard like this. Amazing!” Thank you, Ruth!

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Patricia Evans in Seabrook, New Hampshire, captured the aurora on November 11, 2025. Patricia wrote: “Aurora borealis honors Veterans Day. I was afraid that the cloud cover would prevent viewing the aurora borealis but the reds and greens were amazingly intense! What a goosebump moment!” Thank you, Patricia!

And here’s a YouTube video to round things off!

Picture Parade Four Hundred and Ninety-Six

This short video I watched last Friday and wanted to share it with you all.

(As I type this, I’m getting an error (Error 153) on my video player. I hope in reality everything will be fine.)

The writing that accompanied the above video is:

Astounding Comet Lemmon Pics From Our Community

Comet Lemmon has been the best comet of 2025. It passed closest to Earth on October 21 and closest to the sun on November 8. As it brightened in our skies, EarthSky community members from around the globe captured spectacular images of the comet. See a compilation of editor’s picks here. Thanks to all who submitted!

Producer: Kelly Kizer Whitt

EarthSky.org: https://earthsky.org/

Subscribe: https://subscribe.earthsky.org/

Store: https://earthskystore.org/

Team and About: https://earthsky.org/about/

The Science of Sleep.

Exploring the connection between rest and health.

This is a one-hour video (as in a YouTube video) from an accredited US healthcare educator.

That is all for today. Just to add that sleep is so important.

‘When we turn the clocks ahead this spring, we’ll lose an hour of sleep—but for many Americans, poor sleep is a nightly problem. Lack of sleep takes a toll on physical and mental health, increasing risk for chronic conditions like high blood pressure and obesity. Our expert panelists will unpack the latest research on rest, including how social and environmental factors can impact our sleep. They’ll explore the connections between race, sleep, and health disparities. And they’ll share advice on how to improve sleep quality for better overall health.’