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Arborglyphs – Basque immigrant sheepherders left their marks on aspen trees in the American West

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theconversation.com – John Bieter, Professor of History, Boise State University – 2024-06-20 07:24:06

Carvings made over decades by Basque herders are endangered as their canvas, the aspens, are at risk.

Sawtooth Mountains, 2011, Idaho Basque Arborglyphs Collection, Special Collections and Archives, Albertsons Library, Boise State University

John Bieter, Boise State University; Cheryl Oestreicher, Boise State University, and Iñaki Arrieta Baro, University of Nevada, Reno

Throughout the mountains of the American West, carvings hidden on the trunks of aspen trees tell the stories of the sheepherders who made them as they passed through with their flocks. Most of the men who etched these arborglyphs into the living trees were Basques who, starting with the Gold Rush of the 1840s, had immigrated from the Basque Country that straddles the Pyrenees Mountains.

Our experience of documenting arborglyphs – “lertxun-marrak” in Basque – has deepened over time. At first, we simply tried to decipher what was on the tree. It can be hard to tell what is scarred bark and what is a carving. Gradually, we got better at deciphering the carvings and now hope to spot the oldest and most ornate.

dark outline of a woman's body carved into the white bark of a tree

Nudes are a frequent theme among Basque tree carvings.

Joxe Mallea-Olaetxe Lertxunmarrak Collection, Jon Bilbao Basque Library, University of Nevada, Reno

We also came to appreciate the different styles and themes, like in signatures and writing. One herder carves his name, the date and his hometown; another delves into politics; and another carves a hoped-for female companion.

Viewing the decades-old carvings, we’re surrounded by the quiet and solitude of the high mountain range, whether in the Sierra Nevada, Ruby Mountains or Sawtooth Mountains. We literally stand in the footsteps of the herder who created the arborglyph.

These herders left their marks on the aspens, and now we are part of a research collaboration that aims to document and catalog as many of their arborglyphs and the experiences they record as possible before they disappear. About 25,000 arborglyphs have been documented over time, and there are likely at least as many more left to be recorded before they’re lost.

Gray carved image of a house with text beneath in the silver bark of a tree

Buildings, mostly inspired by Basque architecture, are often represented.

John Merill, 2010, Idaho Basque Arborglyphs Collection, Special Collections and Archives, Albertsons Library, Boise State University

Who were the sheepherders who left their mark?

Beginning almost 200 years ago, Basques emigrated to the American West to pursue economic opportunities, escape compulsory military service or political persecution, and for other personal reasons. Most were lower class, from agrarian backgrounds, with little to no education or English language skills. As the sheepherding industry grew in the West, it offered these immigrants steady work, and Basques became synonymous with sheepherding through the 1970s, when the economy improved in the Basque Country.

The Basque immigrants practiced a seasonal form of herding called transhumance. The herders trailed the sheep up into the high mountains during the spring and summer for grazing, then migrated in the fall back to the valleys where they spent the winter. This annual cycle meant Basque herders spent their summers alone in the hills.

In Basque, Spanish, French and English, they carved into living aspen trees to express their thoughts, dreams, wishes and challenges. Their arborglyphs cover a spectrum of topics: their hometowns, sports, women, love, work, religion, politics and more.

darkened letters carved into bark of white tree trunk

One example of a political statement: ‘Arriba España baño Euzk[adi] Gain[etik]’ translates to ‘Up with Spain but the Basque Country above it.’

Idaho Basque Arborglyphs Collection, Special Collections and Archives, Albertsons Library, Boise State University

For example, they carved political slogans like “Gora Euskadi” (“Up with the Basque Country”), for which they could have been arrested at home. There are carvings of crosses that note the festivals of particular saints, boats depicted by those who hailed from fishing villages, and well-known verses and poems about longing to return to their country.

Sometimes you laugh when you get the joke or the saying that they share. Other times, it can be quite moving as they describe their lives and longings. These carvings reflect a variety of human emotions and experiences, with nostalgia playing a prominent role.

Collecting the carvings virtually

To document these disappearing cultural artifacts, we formed Lertxun-Marrak – The Arborglyph Collaborative, composed of Boise State University, California State University, Bakersfield, and the University of Nevada, Reno in collaboration with the Kern County Museum, the Basque Museum, and the Northeastern Nevada Museum, with the support of the National Historical Publications & Records Commission.

animal silhouettes etched into the gray bark of a tree

A variety of animals are represented, including birds and mammals.

Joxe Mallea-Olaetxe Lertxunmarrak Collection, Jon Bilbao Basque Library, University of Nevada, Reno

We also want to make connections with those who were interested in the carvings: family and friends of those who left the Basque Country for opportunities in the American West; those from local communities who wish to understand the experience of these immigrants; artists who see the aspen trees as a canvas and the carvings as a distinct art; researchers and governmental organizations, hikers, hunters and runners who come upon them in the backcountry, and the greater public.

Unfortunately, age, grazing practices, more frequent and intense fires, and climate change as a whole threaten these carvings. The Arborglyph Collaborative aims to document as many tree carvings as possible before they are gone.

To do so, we follow the herders’ trails through the mountains. It’s easy to walk through an aspen grove and not realize that the bark of the trees are canvases. Having an understanding of the sheepherding area helps us identify groves where herders carved on the aspens. Mature aspen groves with springs close to them are better candidates to contain “lertxun-marrak.” If we find one arborglyph, we can assume that there will be others, since they are usually found in groups in areas with heavy sheepherding traffic.

The techniques used to capture and reproduce tree carvings have evolved along with the available technologies. The Earl Collection of tree carving rubbings, deposited at the Jon Bilbao Basque Library at the University of Nevada, Reno, represents one example of the early efforts.

black outline of a simple sketch of a bird.

The same bird as in the previous picture, here captured by Jean Earl in a rubbing in the 1970s.

Philip I. and Jean Moore Earl Basque Aspen Art of the Sierra Nevada Collection, Jon Bilbao Basque Library, University of Nevada, Reno

Reno residents Jean and Phillip Earl first heard about arborglyphs during a lecture at the university in the 1970s. Intrigued, they began to actively seek out what they first termed “living galleries” and to experiment with methods of preserving the images they found; muslin and black rubbing wax proved the best tools for the job. The Earls devoted 40 years to developing an archival record comprising around 150 rubbings of the carvings that most captured their attention because of their visual appeal.

Along with rubbings, researchers used sketching, still photography and, later, video recordings to document the etched bark of aspens. Another research collection in the Jon Bilbao Basque Library was compiled by one of the first scholars interested in arborglyphs, Joxe Mallea-Olaetxe. In fact, he coined the term lertxun-marrak – literally, “lines/drawings on aspen trees,” the name for arborglyphs in Euskara, the Basque language.

From the 1970s to the 2000s, he documented thousands of arborglyphs, including detailed descriptions, photographs and video recordings, providing a comprehensive view of these cultural artifacts.

YouTube video
The Arborglyph Collaborative is building a catalog of 3D models of the carvings, which anyone can visit and examine virtually. @One Digital Media and Technology Center, University of Nevada, Reno.

Now, we are able to document the arborglyphs with photogrammetry, which creates a three-dimensional model in realistic detail. We’re also able to recreate the carving and its setting in virtual reality, allowing a visitor to immerse themselves in a grove without needing to travel. Smartphones and tablets make it convenient for nearly anyone to engage with arborglyphs from anywhere, at any time, including creating and accessing 3D models of the carvings.

three men facing a tree with carved bark, one is using a device to record it

Part of the current research team during a field trip to document tree carvings in Elko County, Nevada.

Martin Szillat, @One Digital Media and Technology Center, University of Nevada, Reno.

The trees and the Basques

an aspen in a clearing with peeling bark that has some bits of arborglyphs visible

Without high-tech preservation, the arborglyphs will ultimately be lost.

Coulter Summit, Idaho Basque Arborglyphs Collection, Special Collections and Archives, Albertsons Library, Boise State University

The need to preserve these human experiences transformed into artifacts is driven home by encounters like one that happened on a recent documenting trip in the mountains outside of Idaho City, Idaho. One student who was helping take photos and videos and noting GPS locations revealed that her father came to the U.S. from the Basque Country to work as a sheepherder. She’d joined our research team to learn more about his experience. When she found the carvings made by her dad, who had died when she was young, tears ran down her cheeks as she experienced a flood of emotions.

Stories like this demonstrate the value of preserving these artifacts that revive the voices and memories of these immigrants in the American West. Today, increased technological availability and reliable partners are key to achieving this goal. We have much more work to do, more arborglyphs to collect, ways to make them publicly accessible, and more communities to engage with.The Conversation

John Bieter, Professor of History, Boise State University; Cheryl Oestreicher, Professor and Head of Special Collections and Archives for Albertsons Library, Boise State University, and Iñaki Arrieta Baro, Librarian and Head of the Jon Bilbao Basque Library, University of Nevada, Reno

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Perfect brownies baked at high altitude are possible thanks to Colorado’s home economics pioneer Inga Allison

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theconversation.com – Tobi Jacobi, Professor of English, Colorado State University – 2025-04-22 07:47:00

Students work in the high-altitude baking laboratory.
Archives and Special Collections, Colorado State University

Tobi Jacobi, Colorado State University and Caitlin Clark, Colorado State University

Many bakers working at high altitudes have carefully followed a standard recipe only to reach into the oven to find a sunken cake, flat cookies or dry muffins.

Experienced mountain bakers know they need a few tricks to achieve the same results as their fellow artisans working at sea level.

These tricks are more than family lore, however. They originated in the early 20th century thanks to research on high-altitude baking done by Inga Allison, then a professor at Colorado State University. It was Allison’s scientific prowess and experimentation that brought us the possibility of perfect high-altitude brownies and other baked goods.

A recipe for brownies at high altitude.
Inga Allison’s high-altitude brownie recipe.
Archives and Special Collections, Colorado State University

We are two current academics at CSU whose work has been touched by Allison’s legacy.

One of us – Caitlin Clark – still relies on Allison’s lessons a century later in her work as a food scientist in Colorado. The other – Tobi Jacobi – is a scholar of women’s rhetoric and community writing, and an enthusiastic home baker in the Rocky Mountains, who learned about Allison while conducting archival research on women’s work and leadership at CSU.

That research developed into “Knowing Her,” an exhibition Jacobi developed with Suzanne Faris, a CSU sculpture professor. The exhibit highlights dozens of women across 100 years of women’s work and leadership at CSU and will be on display through mid-August 2025 in the CSU Fort Collins campus Morgan Library.

A pioneer in home economics

Inga Allison is one of the fascinating and accomplished women who is part of the exhibit.

Allison was born in 1876 in Illinois and attended the University of Chicago, where she completed the prestigious “science course” work that heavily influenced her career trajectory. Her studies and research also set the stage for her belief that women’s education was more than preparation for domestic life.

In 1908, Allison was hired as a faculty member in home economics at Colorado Agricultural College, which is now CSU. She joined a group of faculty who were beginning to study the effects of altitude on baking and crop growth. The department was located inside Guggenheim Hall, a building that was constructed for home economics education but lacked lab equipment or serious research materials.

A sepia-toned photograph of Inga Allison, a white woman in dark clothes with her hair pulled back.
Inga Allison was a professor of home economics at Colorado Agricultural College, where she developed recipes that worked in high altitudes.
Archives and Special Collections, Colorado State University

Allison took both the land grant mission of the university with its focus on teaching, research and extension and her particular charge to prepare women for the future seriously. She urged her students to move beyond simple conceptions of home economics as mere preparation for domestic life. She wanted them to engage with the physical, biological and social sciences to understand the larger context for home economics work.

Such thinking, according to CSU historian James E. Hansen, pushed women college students in the early 20th century to expand the reach of home economics to include “extension and welfare work, dietetics, institutional management, laboratory research work, child development and teaching.”

News articles from the early 1900s track Allison giving lectures like “The Economic Side of Natural Living” to the Colorado Health Club and talks on domestic science to ladies clubs and at schools across Colorado. One of her talks in 1910 focused on the art of dishwashing.

Allison became the home economics department chair in 1910 and eventually dean. In this leadership role, she urged then-CSU President Charles Lory to fund lab materials for the home economics department. It took 19 years for this dream to come to fruition.

In the meantime, Allison collaborated with Lory, who gave her access to lab equipment in the physics department. She pieced together equipment to conduct research on the relationship between cooking foods in water and atmospheric pressure, but systematic control of heat, temperature and pressure was difficult to achieve.

She sought other ways to conduct high-altitude experiments and traveled across Colorado where she worked with students to test baking recipes in varied conditions, including at 11,797 feet in a shelter house on Fall River Road near Estes Park.

Early 1900s car traveling in the Rocky Mountains.
Inga Allison tested her high-altitude baking recipes at 11,797 feet at the shelter house on Fall River Road, near Estes Park, Colorado.
Archives and Special Collections, Colorado State University

But Allison realized that recipes baked at 5,000 feet in Fort Collins and Denver simply didn’t work in higher altitudes. Little advancement in baking methods occurred until 1927, when the first altitude baking lab in the nation was constructed at CSU thanks to Allison’s research. The results were tangible — and tasty — as public dissemination of altitude-specific baking practices began.

A 1932 bulletin on baking at altitude offers hundreds of formulas for success at heights ranging from 4,000 feet to over 11,000 feet. Its author, Marjorie Peterson, a home economics staff person at the Colorado Experiment Station, credits Allison for her constructive suggestions and support in the development of the booklet.

Science of high-altitude baking

As a senior food scientist in a mountain state, one of us – Caitlin Clark – advises bakers on how to adjust their recipes to compensate for altitude. Thanks to Allison’s research, bakers at high altitude today can anticipate how the lower air pressure will affect their recipes and compensate by making small adjustments.

The first thing you have to understand before heading into the kitchen is that the higher the altitude, the lower the air pressure. This lower pressure has chemical and physical effects on baking.

Air pressure is a force that pushes back on all of the molecules in a system and prevents them from venturing off into the environment. Heat plays the opposite role – it adds energy and pushes molecules to escape.

When water is boiled, molecules escape by turning into steam. The less air pressure is pushing back, the less energy is required to make this happen. That’s why water boils at lower temperatures at higher altitudes – around 200 degrees Fahrenheit in Denver compared with 212 F at sea level.

So, when baking is done at high altitude, steam is produced at a lower temperature and earlier in the baking time. Carbon dioxide produced by leavening agents also expands more rapidly in the thinner air. This causes high-altitude baked goods to rise too early, before their structure has fully set, leading to collapsed cakes and flat muffins. Finally, the rapid evaporation of water leads to over-concentration of sugars and fats in the recipe, which can cause pastries to have a gummy, undesirable texture.

Allison learned that high-altitude bakers could adjust to their environment by reducing the amount of sugar or increasing liquids to prevent over-concentration, and using less of leavening agents like baking soda or baking powder to prevent dough from rising too quickly.

Allison was one of many groundbreaking women in the early 20th century who actively supported higher education for women and advanced research in science, politics, humanities and education in Colorado.

Others included Grace Espy-Patton, a professor of English and sociology at CSU from 1885 to 1896 who founded an early feminist journal and was the first woman to register to vote in Fort Collins. Miriam Palmer was an aphid specialist and master illustrator whose work crafting hyper-realistic wax apples in the early 1900s allowed farmers to confirm rediscovery of the lost Colorado Orange apple, a fruit that has been successfully propagated in recent years.

In 1945, Allison retired as both an emerita professor and emerita dean at CSU. She immediately stepped into the role of student and took classes in Russian and biochemistry.

In the fall of 1958, CSU opened a new dormitory for women that was named Allison Hall in her honor.

“I had supposed that such a thing happened only to the very rich or the very dead,” Allison told reporters at the dedication ceremony.

Read more of our stories about Colorado.The Conversation

Tobi Jacobi, Professor of English, Colorado State University and Caitlin Clark, Senior Food Scientist at the CSU Spur Food Innovation Center, Colorado State University

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Why don’t humans have hair all over their bodies? A biologist explains our lack of fur

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theconversation.com – Maria Chikina, Assistant Professor of Computational and Systems Biology, University of Pittsburgh – 2025-04-21 07:33:00

Some mammals are super hairy, some are not.
Ed Jones/AFP via Getty Images

Maria Chikina, University of Pittsburgh

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to CuriousKidsUS@theconversation.com.


Why don’t humans have hair all over their bodies like other animals? – Murilo, age 5, Brazil


Have you ever wondered why you don’t have thick hair covering your whole body like a dog, cat or gorilla does?

Humans aren’t the only mammals with sparse hair. Elephants, rhinos and naked mole rats also have very little hair. It’s true for some marine mammals, such as whales and dolphins, too.

Scientists think the earliest mammals, which lived at the time of the dinosaurs, were quite hairy. But over hundreds of millions of years, a small handful of mammals, including humans, evolved to have less hair. What’s the advantage of not growing your own fur coat?

I’m a biologist who studies the genes that control hairiness in mammals. Why humans and a small number of other mammals are relatively hairless is an interesting question. It all comes down to whether certain genes are turned on or off.

Hair benefits

Hair and fur have many important jobs. They keep animals warm, protect their skin from the sun and injuries and help them blend into their surroundings.

They even assist animals in sensing their environment. Ever felt a tickle when something almost touches you? That’s your hair helping you detect things nearby.

Humans do have hair all over their bodies, but it is generally sparser and finer than that of our hairier relatives. A notable exception is the hair on our heads, which likely serves to protect the scalp from the sun. In human adults, the thicker hair that develops under the arms and between the legs likely reduces skin friction and aids in cooling by dispersing sweat.

So hair can be pretty beneficial. There must have been a strong evolutionary reason for people to lose so much of it.

Why humans lost their hair

The story begins about 7 million years ago, when humans and chimpanzees took different evolutionary paths. Although scientists can’t be sure why humans became less hairy, we have some strong theories that involve sweat.

Humans have far more sweat glands than chimps and other mammals do. Sweating keeps you cool. As sweat evaporates from your skin, heat energy is carried away from your body. This cooling system was likely crucial for early human ancestors, who lived in the hot African savanna.

Of course, there are plenty of mammals living in hot climates right now that are covered with fur. Early humans were able to hunt those kinds of animals by tiring them out over long chases in the heat – a strategy known as persistence hunting.

Humans didn’t need to be faster than the animals they hunted. They just needed to keep going until their prey got too hot and tired to flee. Being able to sweat a lot, without a thick coat of hair, made this endurance possible.

Genes that control hairiness

To better understand hairiness in mammals, my research team compared the genetic information of 62 different mammals, from humans to armadillos to dogs and squirrels. By lining up the DNA of all these different species, we were able to zero in on the genes linked to keeping or losing body hair.

Among the many discoveries we made, we learned humans still carry all the genes needed for a full coat of hair – they are just muted or switched off.

In the story of “Beauty and the Beast,” the Beast is covered in thick fur, which might seem like pure fantasy. But in real life some rare conditions can cause people to grow a lot of hair all over their bodies. This condition, called hypertrichosis, is very unusual and has been called “werewolf syndrome” because of how people who have it look.

A detailed painting of a man and a woman standing next to one another in historical looking clothes. The man's face is covered in hair, while the woman's is not.
Petrus Gonsalvus and his wife, Catherine, painted by Joris Hoefnagel, circa 1575.
National Gallery of Art

In the 1500s, a Spanish man named Petrus Gonsalvus was born with hypertrichosis. As a child he was sent in an iron cage like an animal to Henry II of France as a gift. It wasn’t long before the king realized Petrus was like any other person and could be educated. In time, he married a lady, forming the inspiration for the “Beauty and the Beast” story.

While you will probably never meet someone with this rare trait, it shows how genes can lead to unique and surprising changes in hair growth.


Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.The Conversation

Maria Chikina, Assistant Professor of Computational and Systems Biology, University of Pittsburgh

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Scientists found a potential sign of life on a distant planet – an astronomer explains why many are still skeptical

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theconversation.com – Daniel Apai, Associate Dean for Research and Professor of Astronomy and Planetary Sciences, University of Arizona – 2025-04-18 17:44:00

An illustration of the exoplanet K2-18b, which some research suggests may be covered by deep oceans.
NASA, ESA, CSA, Joseph Olmsted (STScI)

Daniel Apai, University of Arizona

A team of astronomers announced on April 16, 2025, that in the process of studying a planet around another star, they had found evidence for an unexpected atmospheric gas. On Earth, that gas – called dimethyl sulfide – is mostly produced by living organisms.

In April 2024, the James Webb Space Telescope stared at the host star of the planet K2-18b for nearly six hours. During that time, the orbiting planet passed in front of the star. Starlight filtered through its atmosphere, carrying the fingerprints of atmospheric molecules to the telescope.

A diagram showing planets and stars emitting light, which goes through JWST detectors, where it's split into different wavelengths to make a spectrum. Each spectrum suggests the presence of a different element.
JWST’s cameras can detect molecules in the atmosphere of a planet by looking at light that passed through that atmosphere.
European Space Agency

By comparing those fingerprints to 20 different molecules that they would potentially expect to observe in the atmosphere, the astronomers concluded that the most probable match was a gas that, on Earth, is a good indicator of life.

I am an astronomer and astrobiologist who studies planets around other stars and their atmospheres. In my work, I try to understand which nearby planets may be suitable for life.

K2-18b, a mysterious world

To understand what this discovery means, let’s start with the bizarre world it was found in. The planet’s name is K2-18b, meaning it is the first planet in the 18th planetary system found by the extended NASA Kepler mission, K2. Astronomers assign the “b” label to the first planet in the system, not “a,” to avoid possible confusion with the star.

K2-18b is a little over 120 light-years from Earth – on a galactic scale, this world is practically in our backyard.

Although astronomers know very little about K2-18b, we do know that it is very unlike Earth. To start, it is about eight times more massive than Earth, and it has a volume that’s about 18 times larger. This means that it’s only about half as dense as Earth. In other words, it must have a lot of water, which isn’t very dense, or a very big atmosphere, which is even less dense.

Astronomers think that this world could either be a smaller version of our solar system’s ice giant Neptune, called a mini-Neptune, or perhaps a rocky planet with no water but a massive hydrogen atmosphere, called a gas dwarf.

Another option, as University of Cambridge astronomer Nikku Madhusudhan recently proposed, is that the planet is a “hycean world”.

That term means hydrogen-over-ocean, since astronomers predict that hycean worlds are planets with global oceans many times deeper than Earth’s oceans, and without any continents. These oceans are covered by massive hydrogen atmospheres that are thousands of miles high.

Astronomers do not know yet for certain that hycean worlds exist, but models for what those would look like match the limited data JWST and other telescopes have collected on K2-18b.

This is where the story becomes exciting. Mini-Neptunes and gas dwarfs are unlikely to be hospitable for life, because they probably don’t have liquid water, and their interior surfaces have enormous pressures. But a hycean planet would have a large and likely temperate ocean. So could the oceans of hycean worlds be habitable – or even inhabited?

Detecting DMS

In 2023, Madhusudhan and his colleagues used the James Webb Space Telescope’s short-wavelength infrared camera to inspect starlight that filtered through K2-18b’s atmosphere for the first time.

They found evidence for the presence of two simple carbon-bearing molecules – carbon monoxide and methane – and showed that the planet’s upper atmosphere lacked water vapor. This atmospheric composition supported, but did not prove, the idea that K2-18b could be a hycean world. In a hycean world, water would be trapped in the deeper and warmer atmosphere, closer to the oceans than the upper atmosphere probed by JWST observations.

Intriguingly, the data also showed an additional, very weak signal. The team found that this weak signal matched a gas called dimethyl sulfide, or DMS. On Earth, DMS is produced in large quantities by marine algae. It has very few, if any, nonbiological sources.

This signal made the initial detection exciting: on a planet that may have a massive ocean, there is likely a gas that is, on Earth, emitted by biological organisms.

An illustration of what scientists imagine K2-18b to look like, which looks a little like Earth, with clouds and a translucent surface.
K2-18b could have a deep ocean spanning the planet, and a hydrogen atmosphere.
Amanda Smith, Nikku Madhusudhan (University of Cambridge), CC BY-SA

Scientists had a mixed response to this initial announcement. While the findings were exciting, some astronomers pointed out that the DMS signal seen was weak and that the hycean nature of K2-18b is very uncertain.

To address these concerns, Mashusudhan’s team turned JWST back to K2-18b a year later. This time, they used another camera on JWST that looks for another range of wavelengths of light. The new results – announced on April 16, 2025 – supported their initial findings.

These new data show a stronger – but still relatively weak – signal that the team attributes to DMS or a very similar molecule. The fact that the DMS signal showed up on another camera during another set of observations made the interpretation of DMS in the atmosphere stronger.

Madhusudhan’s team also presented a very detailed analysis of the uncertainties in the data and interpretation. In real-life measurements, there are always some uncertainties. They found that these uncertainties are unlikely to account for the signal in the data, further supporting the DMS interpretation. As an astronomer, I find that analysis exciting.

Is life out there?

Does this mean that scientists have found life on another world? Perhaps – but we still cannot be sure.

First, does K2-18b really have an ocean deep beneath its thick atmosphere? Astronomers should test this.

Second, is the signal seen in two cameras two years apart really from dimethyl sulfide? Scientists will need more sensitive measurements and more observations of the planet’s atmosphere to be sure.

Third, if it is indeed DMS, does this mean that there is life? This may be the most difficult question to answer. Life itself is not detectable with existing technology. Astronomers will need to evaluate and exclude all other potential options to build their confidence in this possibility.

The new measurements may lead researchers toward a historic discovery. However, important uncertainties remain. Astrobiologists will need a much deeper understanding of K2-18b and similar worlds before they can be confident in the presence of DMS and its interpretation as a signature of life.

Scientists around the world are already scrutinizing the published study and will work on new tests of the findings, since independent verification is at the heart of science.

Moving forward, K2-18b is going to be an important target for JWST, the world’s most sensitive telescope. JWST may soon observe other potential hycean worlds to see if the signal appears in the atmospheres of those planets, too.

With more data, these tentative conclusions may not stand the test of time. But for now, just the prospect that astronomers may have detected gasses emitted by an alien ecosystem that bubbled up in a dark, blue-hued alien ocean is an incredibly fascinating possibility.

Regardless of the true nature of K2-18b, the new results show how using the JWST to survey other worlds for clues of alien life will guarantee that the next years will be thrilling for astrobiologists.The Conversation

Daniel Apai, Associate Dean for Research and Professor of Astronomy and Planetary Sciences, University of Arizona

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