Filming ICE is legal but exposes you to digital tracking – here’s how to minimize the risk

Source: The Conversation – USA – By Nicole M. Bennett, Ph.D. Candidate in Geography and Assistant Director at the Center for Refugee Studies, Indiana University

If you’re going to record ICE agents, recognize that the risks go beyond physical confrontation. Madison Thorn/Anadolu via Getty Images

When an Immigration and Customs Enforcement agent shot and killed Renee Nicole Good in south Minneapolis on Jan. 7, 2026, what happened next looked familiar, at least on the surface. Within hours, cellphone footage spread online and eyewitness accounts contradicted official statements, while video analysts slowed the clip down frame by frame to answer a basic question: Did she pose the threat federal officials claimed?

What’s changed since Minneapolis became a global reference point for bystander video in 2020 in the wake of George Floyd’s murder is how thoroughly camera systems, especially smartphones, are now entangled with the wider surveillance ecosystem.

I am a researcher who studies the intersection of data governance, digital technologies and the U.S. federal government. The hard truth for anyone filming law enforcement today is that the same technologies that can hold the state accountable can also make ordinary people more visible to the state.

Recording is often protected speech. But recording, and especially sharing, creates data that can be searched, linked, purchased and reused.

Video can challenge power. It can also attract it.

Targeting the watchers

Documentation can be the difference between an official narrative and an evidence-based public record. Courts in much of the U.S. have recognized a First Amendment right to record police in public while they perform official duties, subject to reasonable restrictions. For example, you can’t physically interfere with police.

a man wearing a tactical vest and face mask points in the direction of the viewer
An ICE officer tells a photographer to back up.
AP Photo/Adam Gray

However, that right is uneven across jurisdictions and vulnerable in practice, especially when police claim someone is interfering, or when state laws impose distances people must maintain from law enforcement actions – practices that chill filming.

While the legal landscape of recording law enforcement is important to understand, your safety is also a major consideration. In the days after Good’s killing, Minneapolis saw other viral clips documenting immigration enforcement and protests, along with agents’ forceful engagement with people near those scenes, including photographers.

It’s difficult to know how many people have been targeted by agents for recording. In Illinois in late 2025, the U.S. Press Freedom Tracker, operated by advocacy group Freedom of the Press Foundation, documented multiple incidents in which journalists covering ICE-facility protests reported being shot with crowd-control munitions or tackled and arrested while filming.

These incidents underscore that documentation isn’t risk-free. There is an additional layer of safety beyond the physical to take into account: your increased risk of digital exposure. The legal right to record doesn’t prevent your recording from becoming data that others can use.

Both camera and tracking device

In practical terms, smartphones generate at least three kinds of digital exposure.

The first is identification risk, including through facial recognition technology. When you post footage, you may be sharing identifiable faces, tattoos, voices, license plates, school logos or even a distinctive jacket. That can enable law enforcement to identify people in your recordings through investigative tools, and online crowds to identify people and dox or harass them, or both.

That risk grows when agencies deploy facial recognition in the field. For example, ICE is using a facial recognition app called Mobile Fortify.

Facial recognition accuracy also isn’t neutral. National Institute of Standards and Technology testing has documented that the technology does not perform equally across different demographic groups, meaning the risk of misidentification is not evenly distributed across groups. For example, studies have shown lower recognition accuracy for people with darker skin color.

Second is the risk of revealing your location. Footage isn’t just images. Photos and video files often contain metadata such as timestamps and locations, and platforms also maintain additional logs. Even if you never post, your phone still emits a steady stream of location signals.

This matters because agencies can obtain location through multiple channels, often with different levels of oversight.

Agencies can request location or other data from companies through warrants or court orders, including geofence warrants that sweep up data about every device in a place during a set time window.

Agencies can also buy location data from brokers. The Federal Trade Commission has penalized firms for unlawfully selling sensitive location information.

Data brokers collect location data from people’s phones and sell it, including to law enforcement and federal agencies.

Agencies also use specialized “area monitoring” tools: ICE purchased systems capable of tracking phones across an entire neighborhood or block over time, raising civil liberties concerns. The tools could track a phone from the time and place of a protest – for example, to a home or workplace.

There are more pathways for tracking than most people realize, and not all are constrained by the courtroom rules people picture when they think “warrant.”

The third type of potential exposure is the risk of having your phone seized. If police seize your phone, temporarily or for evidence, your exposure isn’t just the video you shot. It can include your contacts and message history, your photo roll, location history and cloud accounts synced to the device.

Civil liberties groups that publish protest safety guidance consistently recommend disabling the face and fingerprint unlocking features and using a strong passcode. Law enforcement officials can compel you to use biometrics more easily in some contexts than reveal memorized secrets.

Digital safety when recording police

This isn’t legal advice, and nothing is risk-free. But if you want to keep the accountability benefits of filming while reducing your digital exposure, here are steps you can take to address the risks.

Before you go, decide what you’re optimizing for, whether it is preserving evidence quickly or minimizing traceability, because those goals can conflict. Harden your lock screen with a long passcode, disable face and fingerprint ID, turn off message previews and reduce the risk of what you carry by logging out of sensitive accounts and removing unnecessary apps. Even consider leaving your primary phone at home if that’s realistic.

If you’re worried about having your recording deleted, plan ahead for how you’ll secure footage. You can either send it to a trusted person through an encrypted app or keep it offline until you’re safe.

While filming, keep your phone locked when possible using the camera-from-lock-screen feature and avoid livestreaming if identification risk is high, since live posts can expose your location in real time. Focus on documenting context rather than creating viral clips: Capture wide shots, key actions and clear time-and-place markers, and limit close-ups of bystanders. Assume faces are searchable, and if you can’t protect people in the moment, consider waiting to share until you can edit safely.

Afterward, back up securely and edit for privacy before posting by blurring faces, tattoos and license plates, removing metadata, and sharing a privacy-edited copy instead of the raw file. Think strategically about distribution because sometimes it’s safer to provide footage to journalists, lawyers or civil rights groups who can authenticate it without exposing everyone to mass identification. And remember the “second audience” beyond police, including employers, trolls and data brokers.

A new reality

Recording law enforcement in public is often a vital democratic check, especially when official narratives and reality conflict, as they have in Minneapolis since Jan. 7, 2026.

But the camera in your pocket is also part of a maturing surveillance ecosystem, one that links video, facial recognition and location data in ways most people never consented to and often don’t fully recognize.

In 2026, filming still matters. The challenge is ensuring the act of witnessing doesn’t quietly become a new form of exposure.

The Conversation

Nicole M. Bennett is affiliated with the Center for Refugee Studies at Indiana University.

ref. Filming ICE is legal but exposes you to digital tracking – here’s how to minimize the risk – https://theconversation.com/filming-ice-is-legal-but-exposes-you-to-digital-tracking-heres-how-to-minimize-the-risk-273566

America’s next big clean energy resource could come from coal mine pollution – if we can agree on who owns it

Source: The Conversation – USA (2) – By Hélène Nguemgaing, Assistant Clinical Professor of Critical Resources & Sustainability Analytics, University of Maryland

Acid mine waste turns rocks orange along Shamokin Creek in Pennsylvania.
Jake C/Wikimedia Commons, CC BY-SA

Across Appalachia, rust-colored water seeps from abandoned coal mines, staining rocks orange and coating stream beds with metals. These acidic discharges, known as acid mine drainage, are among the region’s most persistent environmental problems. They disrupt aquatic life, corrode pipes and can contaminate drinking water for decades.

However, hidden in that orange drainage are valuable metals known as rare earth elements that are vital for many technologies the U.S. relies on, including smartphones, wind turbines and military jets. In fact, studies have found that the concentrations of rare earths in acid mine waste can be comparable to the amount in ores mined to extract rare earths.

Scientists estimate that more than 13,700 miles (22,000 kilometers) of U.S. streams, predominantly in Pennsylvania and West Virginia, are contaminated with acid mine discharge.

A closer look at acid mine drainage from abandoned mines in Pennsylvania. Pennsylvania Fish and Boat Commission.

We and our colleagues at West Virginia University have been working on ways to turn the acid waste in those bright orange creeks into a reliable domestic source for rare earths while also cleaning the water.

Experiments show extraction can work. If states can also sort out who owns that mine waste, the environmental cost of mining might help power a clean energy future.

Rare earths face a supply chain risk

Rare earth elements are a group of 17 metals, also classified as critical minerals, that are considered vital to the nation’s economy or security.

Despite their name, rare earth elements are not all that rare. They occur in many places around the planet, but in small quantities mixed with other minerals, which makes them costly and complex to separate and refine.

A mine and buildings with mountains in the background.
MP Materials’ Mountain Pass Rare Earth Mine and Processing Facility, in California near the Nevada border, is one of the few rare earth mines in the U.S.
Tmy350/Wikimedia Commons, CC BY-SA

China controls about 70% of global rare earth production and nearly all refining capacity. This near monopoly gives the Chinese government the power to influence prices, export policies and access to rare earth elements. China has used that power in trade disputes as recently as 2025.

The United States, which currently imports about 80% of the rare earth elements it uses, sees China’s control over these critical minerals as a risk and has made locating domestic sources a national priority.

The U.S. Geological Survey has been mapping locations for potential rare earth mining, shown in pink. But it takes years to explore a locations and then get a mine up and running.
USGS

Although the U.S. Geological Survey has been mapping potential locations for extracting rare earth elements, getting from exploration to production takes years. That’s why unconventional sources, like extracting rare earth elements from acid mine waste, are drawing interest.

Turning a mine waste problem into a solution

Acid mine drainage forms when sulfide minerals, such as pyrite, are exposed to air during mining. This creates sulfuric acid, which then dissolves heavy metals such as copper, lead and mercury from surrounding rock. The metals end up in groundwater and creeks, where iron in the mix gives the water an orange color.

Expensive treatment systems can neutralize the acid, with the dissolved metals settling into an orange sludge in treatment ponds.

For decades, that sludge was treated as hazardous waste and hauled to landfills. But scientists at West Virginia University and the National Energy Technology Laboratory have found that it contains concentrations of rare earth elements comparable to those found in mined ores. These elements are also easier to extract from acid mine waste because the acidic water has already released them from the surrounding rock.

Metals flowing from acid mine waste make a creek look orange.
Acid mine drainage flowing into Decker’s Creek in Morgantown, West Virginia, in 2024.
Helene Nguemgaing

Experiments have shown how the metals can be extracted: Researchers collected sludge, separated out rare earth elements using water-safe chemistry, and then returned the cleaner water to nearby streams.

It is like mining without digging, turning something harmful into a useful resource. If scaled up, this process could lower cleanup costs, create local jobs and strengthen America’s supply of materials needed for renewable energy and high-tech manufacturing.

But there’s a problem: Who owns the recovered minerals?

The ownership question

Traditional mining law covers minerals underground, not those extracted from water naturally running off abandoned mine sites.

Nonprofit watershed groups that treat mine waste to clean up the water often receive public funding meant solely for environmental cleanup. If these groups start selling recovered rare earth elements, they could generate revenue for more stream cleanup projects, but they might also risk violating grant terms or nonprofit rules.

To better understand the policy challenges, we surveyed mine water treatment operators across Pennsylvania and West Virginia. The majority of treatment systems were under landowner agreements in which the operators had no permanent property rights. Most operators said “ownership uncertainty” was one of the biggest barriers to investment in the recovery of rare earth elements, projects that can cost millions of dollars.

Not surprisingly, water treatment operators who owned the land where treatment was taking place were much more likely to be interested in rare earth element extraction.

A map shows many acid mine drainage sites, largely in the column from the southwest to the northeast.
Map of acid mine drainage sites in West Virginia.
Created by Helene Nguemgaing, based on data from West Virginia Department of Environmental Protection, West Virginia Office of GIS Coordination, and U.S. Geological Survey

West Virginia took steps in 2022 to boost rare earth recovery, innovation and cleanup of acid mine drainage. A new law gives ownership of recovered rare earth elements to whoever extracts them. So far, the law has not been applied to large-scale projects.

Across the border, Pennsylvania’s Environmental Good Samaritan Act protects volunteers who treat mine water from liability but says nothing about ownership.

A map shows many acid mine drainage sites, particularly in the western part of the state.
Map of acid mine drainage sites in Pennsylvania.
Created by Helene Nguemgaing, based on data from Pennsylvania Spatial Data Access

This difference matters. Clear rules like West Virginia’s provide greater certainty, while the lack of guidance in Pennsylvania can leave companies and nonprofits hesitant about undertaking expensive recovery projects. Among the treatment operators we surveyed, interest in rare earth element extraction was twice as high in West Virginia than in Pennsylvania.

The economics of waste to value

Recovering rare earth elements from mine water won’t replace conventional mining. The quantities available at drainage sites are far smaller than those produced by large mines, even though the concentration can be just as high, and the technology to extract them from mine waste is still developing.

Still, the use of mine waste offers a promising way to supplement the supply of rare earth elements with a domestic source and help offset environmental costs while cleaning up polluted streams.

Early studies suggest that recovering rare earth elements using technologies being developed today could be profitable, particularly when the projects also recover additional critical materials, such as cobalt and manganese, which are used in industrial processes and batteries. Extraction methods are improving, too, making the process safer, cleaner and cheaper.

Government incentives, research funding and public-private partnerships could speed this progress, much as subsidies support fossil fuel extraction and have helped solar and wind power scale up in providing electricity.

Treating acid mine drainage and extracting its valuable rare earth elements offers a way to transform pollution into prosperity. Creating policies that clarify ownership, investing in research and supporting responsible recovery could ensure that Appalachian communities benefit from this new chapter, one in which cleanup and clean energy advance together.

The Conversation

The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.

ref. America’s next big clean energy resource could come from coal mine pollution – if we can agree on who owns it – https://theconversation.com/americas-next-big-clean-energy-resource-could-come-from-coal-mine-pollution-if-we-can-agree-on-who-owns-it-272029

Despite its steep environmental costs, AI might also help save the planet

Source: The Conversation – USA (2) – By Nir Kshetri, Professor of Management, University of North Carolina – Greensboro

The rapid growth of artificial intelligence has sharply increased electricity and water consumption, raising concerns about the technology’s environmental footprint and carbon emissions. But the story is more complicated than that.

I study emerging technologies and how their development and deployment influence economic, institutional and societal outcomes, including environmental sustainability. From my research, I see that even as AI uses a lot of energy, it can also make systems cleaner and smarter.

AI is already helping to save energy and water, cut emissions and make businesses more efficient in agriculture, data centers, the energy industry, building heating and cooling, and aviation.

A tractor moves alongside a field with rows of crops.
Agricultural irrigation accounts for an enormous amount of the world’s water use.
AP Photo/Luca Bruno

Agriculture

Agriculture is responsible for nearly 70% of the world’s freshwater use, and competition for water is growing.

AI is helping farmers use water more efficiently. Argentinian climate tech startup Kilimo, for example, tackles water scarcity with an AI-powered irrigation platform. The software uses large amounts of data, machine learning, and weather and satellite measurements to determine when and how much to water which areas of fields, ensuring that only the plants that actually need water receive it.

Chile’s Ministry of Agriculture has found that in that country’s Biobío region, farms using Kilimo’s precision irrigation systems have reduced water use by up to 30% while avoiding overirrigation. Using less water also reduces the amount of energy needed to pump it from the ground and around a farm.

Kilimo is one example that shows how AI can create economic incentives for sustainability: The amount of water farmers save from precision irrigation is verified, and credits for those savings are sold to local companies that want to offset some of their water use. The farmers then earn a profit – often 20% to 40% above their initial investment.

Data centers

U.S. data centers consumed about 176 terawatt-hours of electricity in 2023, accounting for roughly 4.4% of total U.S. electricity use. This number increased to 183 TWh in 2024. This growing energy footprint has made improving data center efficiency a critical priority for the operators of the data centers themselves, as well as the companies that rely on them – including cloud providers, tech firms and large enterprises running AI workloads – both to reduce costs and meet sustainability and regulatory goals.

AI is helping data centers become more efficient. The number of global internet users grew from 1.9 billion in 2010 to 5.6 billion in 2025. Global internet traffic surged from 20.2 exabytes per month in 2010 to 521.9 exabytes per month in 2025 – a more than 25-fold increase.

Despite the surge in internet traffic and users, data center electricity consumption has grown more moderately, rising from 1% of global electricity use in 2010 to 2% in 2025. Much of this is thanks to efficiency gains, including those enabled by AI.

AI systems analyze operational data in data centers – including workloads, temperature, cooling efficiency and energy use – to spot energy-hungry tasks. It adjusts computing resources to match demand and optimizes cooling. This lets data centers run smoothly without wasting electricity.

At Microsoft, AI is improving energy efficiency by using predictive analytics to schedule computing tasks. This lets servers enter low-power modes during periods of low demand, saving electricity during slower times. Meta uses AI to control cooling and airflow in its data centers. The systems stay safe while using less energy than they might otherwise.

In Frankfurt, Germany, Equinix uses AI to manage cooling and adjust energy use at its data center based on real-time weather. This improved operational efficiency by 9%, The New York Times reported.

An overhead view shows a power substation with wires and equipment.
Artificial intelligence systems use a lot of energy, but they can also analyze energy use to find efficiencies.
Joe Raedle/Getty Images

Energy and fuels

Energy companies are using AI to boost efficiency and cut emissions. They deploy drones with cameras to inspect pipelines. AI systems analyze the images to more quickly detect corrosion, cracks, dents and leaks, which allows problems to be addressed before they escalate, improving overall safety and reliability.

Shell has AI systems that monitor methane emissions from its facilities by analyzing methane concentrations and wind data, such as speed and direction. This helps the system track how methane disperses, enabling it to pinpoint emission sources and optimize energy use. By identifying the largest leaks quickly, the system allows targeted maintenance and operational adjustments to further reduce emissions. Using that technology, the company says it aims to nearly eliminate methane leaks by 2030.

AI could speed up innovation in clean energy by improving solar panels, batteries and carbon-capture systems. In the longer term, it could enable major breakthroughs, including advanced biofuels or even usable nuclear fusion, while helping track and manage carbon-absorbing resources such as forests, wetlands and carbon storage facilities.

Shell uses AI across its operations to cut emissions. Its process optimizer for liquefied natural gas analyzes sensor data to find more efficient equipment settings, boosting energy efficiency and reducing emissions.

People talk in a room with many computer screens and large diagrams on the wall.
Buildings in central Copenhagen are heated in a coordinated system with a complex control room.
Bernd von Jutrczenka/picture alliance via Getty Images

Buildings and district heating

The energy needed to heat, cool and power buildings is responsible for roughly 28% of total global emissions. AI initiatives are starting to reduce building emissions through smart management and predictive optimization.

In downtown Copenhagen, for instance, the local utility company HOFOR deployed thousands of sensors tracking temperatures, humidity and building energy flows. The system uses information about each building to forecast heating needs 24 hours in advance and automatically adjust supply to match demand.

The Copenhagen system was first piloted in schools and multifamily housing, with support from the Nordic Smart City Network and climate-innovation grants. It has since expanded to dozens of sites. Results were clear: Across participating buildings, energy use fell 15% to 25%, peak heating demand dropped by up to 30%, and carbon dioxide emissions decreased by around 10,000 tonnes per year.

AI can also help households and offices save energy. Smart home systems optimize heating, cooling and appliance use. Researchers at the Lawrence Berkeley National Laboratory found that by adopting AI, medium-sized office buildings in the U.S. could reduce energy use by 21% and cut carbon dioxide emissions by 35%.

Aviation

About 2% of all human-caused carbon dioxide emissions in 2023 came from aviation, which emitted about 882 megatons of carbon dioxide.

Contrails, the thin ice clouds formed when aircraft exhaust freezes at cruising altitudes, contribute more than one-third of aviation’s overall warming effect by trapping heat in the atmosphere. AI can optimize flight routes and altitudes in real time to reduce contrail formation by avoiding areas where the air is more humid and therefore more likely to produce contrails.

Airlines have also used AI to improve fuel efficiency. In 2023, Alaska Airlines used 1.2 million gallons less fuel by using AI to analyze weather, wind, turbulence, airspace restrictions and traffic to recommend the most efficient routes, saving around 5% on fuel and emissions for longer flights.

In short, AI affects the environment in both positive and negative ways. Already, it has helped industries cut energy use, lower emissions and use water more efficiently. Expanding these solutions could drive a cleaner, more sustainable planet.

The Conversation

Nir Kshetri does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

ref. Despite its steep environmental costs, AI might also help save the planet – https://theconversation.com/despite-its-steep-environmental-costs-ai-might-also-help-save-the-planet-272474

Federal immigration enforcement near schools disrupts attendance, traumatizes students and damages their academic performance

Source: The Conversation – USA (2) – By Carolyn Sattin-Bajaj, Associate Professor of Education, University of California, Santa Barbara

High school students gather for an anti-ICE protest outside the state capitol in St. Paul, Minn., on Jan. 14, 2026. Octavio Jones/AFP via Getty Images

The Trump administration’s recent surge of more than 3,000 federal agents to Minneapolis and St. Paul, Minnesota, is creating ripple effects for students, teachers and parents that go well beyond ongoing protests against Immigration and Customs Enforcement and Customs and Border Protection. These protests escalated after an ICE agent shot and killed Renee Nicole Good on Jan. 7, 2026.

Some Twin Cities parents are arranging security patrols to look out for ICE agents, while others are keeping their kids home altogether. Several large Minneapolis-St. Paul school districts announced on Jan. 15 that they would offer remote learning so students could stay home.

Amy Lieberman, The Conversation U.S. education editor, spoke with Carolyn-Sattin-Bajaj, a scholar of education and immigrant youth, to better understand what regulations restrict ICE’s presence at schools – and how schools can support students and parents concerned about the recent surge of immigrant arrests and deportations in Minnesota.

A man in a green army uniform with a vest that says 'Border Patrol' stands over a person who lies face down in the snow.
U.S. Border Patrol agents detain a person near Roosevelt High School in Minneapolis on Jan. 7, 2026.
Kerem Yucel/AFP via Getty Images

What prevents ICE from walking into a school building?

The Obama administration issued a memo in 2011 that said federal officials should not conduct immigration enforcement work near sensitive locations, meaning schools and houses of worship. The Biden administration also had this policy in place.

President Donald Trump revoked this memo in January 2025. So now, schools are no longer off-limits to federal immigration agencies, including ICE.

That doesn’t mean ICE or Border Patrol agents can march into a school building to arrest someone. While these officers can freely enter public areas of a school, like a parking lot or lobby, school officials are not legally obligated to admit ICE agents into private spaces like classrooms. ICE officers can enter a classroom if they show a valid federal judicial warrant, signed by a judge – or if there are extreme circumstances that allow them to legally circumvent having a warrant.

School officials are also not required to release information about which kids are enrolled at their school or not, and schools do not collect information about students’ immigration status, so that data cannot be shared.

Some school districts have been developing or revising protocols on how to respond if ICE comes to their schools. A lot of these protocols
include recommendations on naming a district superintendent or another local official as the point person for ICE.

How unprecedented is it for ICE to arrest people outside or inside a school?

ICE’s presence at – or near – schools has significantly increased under the second Trump administration.

We have seen violence on school grounds, with ICE attacking students and protesters at Roosevelt High School on Jan. 7 in Minneapolis. In Crystal, Minn., a student’s parent was arrested by ICE personnel on Jan. 14 while waiting for their child at a bus stop.

Even just the threat of ICE agents approaching and arresting people en route to school, or at a school itself, is changing people’s behavior. Some parents in Minnesota and other places no longer take their children to and from school, and have to find other ways to get their kids there. This also affects how many people come to community events and activities held at school.

At one California middle school, the annual moving-up ceremony for students typically held outside had to be delayed in June 2025 after there was a credible rumor that ICE was planning to show up. The district had procedures in place. Because the event was held in an open public space, administrators were stationed at every entrance in case ICE agents turned up – though they didn’t. However, some graduates did not have any relatives there to watch them watch across the stage during the ceremony.

What other considerations are at the forefront of school administrators’ minds in regard to ICE?

The question that is top of mind for many district administrators, school leaders, teachers and other school personnel is “What happens if ICE shows up at our school?”

I think it is important that districts and schools have a clear plan in place that is widely communicated to all adults working in schools, and to students and parents. This should be paired with straightforward and recurrent training for educators on what they might expect if ICE comes to their schools and how to put their schools’ plans in place.

Yet, considering what to do if ICE comes to a school is just the tip of the iceberg. There are approximately 1.5 million children under 18 who are undocumented immigrants and about 4.4 million U.S.-born children who are citizens but have at least one undocumented parent. Many of these students are experiencing significant hardship, including interruptions to their schooling, and other forms of instability that affect their ability to learn and overall well-being.

A man wearing a green vest and pants stands near another man also in a green uniform, in front of a red brick building.
U.S. Border Patrol Commander Gregory Bovino argues with protesters near Roosevelt High School in Minneapolis on Jan. 7, 2026.
Kerem Yucel/AFP via Getty Images

What does your research show on the effects immigration enforcement can have on these students?

My research in seven large California school districts, conducted in 2021, showed that immigration arrests were linked to declines in students’ academic achievement, attendance and other measures of a school’s climate and safety for these students. The biggest declines were among Latino students, especially those who were English language learners.

In another 2023 study of an immigration workplace raid in Texas, a colleague and I found increased student absenteeism, declines in reading and math test scores, and sharp rises in the number of high school students leaving the district. Most often, it was the Latino and multilingual students enrolled in schools in the four counties closest to the raid who were not attending school immediately after the event, or experienced declining test scores.

These consequences persisted. Some of these students were less likely than others to later enroll in four-year colleges. Significantly, not just students who are most likely to have relatives targeted for deportation experienced these effects.

My own research and that of other scholars also show that many teachers are not well prepared for the current realities. But they are eager to know more about their immigrant students’ rights, the resources available to them and how they can serve as allies and advocates.

I believe that to best support students during these troubling times, teachers need better training and guidance on how to navigate challenging conversations about immigration enforcement threats, and how to deal with students’ (and their own) anxiety, uncertainty and trauma.

The Conversation

Carolyn Sattin-Bajaj receives funding from the University of California, Santa Barbara and the Spencer Foundation

ref. Federal immigration enforcement near schools disrupts attendance, traumatizes students and damages their academic performance – https://theconversation.com/federal-immigration-enforcement-near-schools-disrupts-attendance-traumatizes-students-and-damages-their-academic-performance-273325

Why ‘unwinding’ with screens may be making us more stressed – here’s what to try instead

Source: The Conversation – USA (3) – By Robin Pickering, Professor and Chair of Public Health, Gonzaga University

Using multiple digital devices at once can be highly distracting and overstimulating. Riska/E+ via Getty Images

As Americans increasingly report feeling overwhelmed by daily life, many are using self-care to cope. Conversations and social media feeds are saturated with the language of “me time,” burnout, boundaries and nervous system regulation.

To meet this demand, the wellness industry has grown into a multitrillion-dollar global market. Myriad providers offer products, services and lifestyle prescriptions that promise calm, balance and restoration.

Paradoxically, though, even as interest in self-care continues to grow, Americans’ mental health is getting worse.

I am a professor of public health who studies health behaviors and the gap between intentions and outcomes. I became interested in this self-care paradox recently, after I suffered from a concussion. I was prescribed two months of strictly screen-free cognitive rest – no television, email, Zooming, social media, streaming or texting.

The benefits were almost immediate, and they surprised me. I slept better, had a longer attention span and had a newfound sense of mental quiet. These effects reflected a well-established principle in neuroscience: When cognitive and emotional stimuli decrease, the brain’s regulatory systems can recover from overload and chronic stress.

Obviously, most people can’t go 100% screen-free for days, much less months, but the underlying principle offers a powerful lesson for practicing effective self-care.

A nation under strain

Americans’ self-rated mental health is now at the lowest point since Gallup started tracking this issue in 2001. National surveys consistently detect high levels of stress and emotional strain.

Roughly one-third of U.S. adults report feeling overwhelmed most days. Sleep disruption, anxiety, poor concentration and emotional exhaustion are widespread, particularly among young adults and women.

Chronic disease patterns mirror this strain. When daily stress becomes chronic, it can trigger biological changes that increase the risk of long-term conditions like heart disease and diabetes. The Centers for Disease Control and Prevention reports that 6 in 10 U.S. adults live with at least one chronic condition, and 4 in 10 live with multiple chronic conditions.

Stress triggers physiological responses that can lead to a range of symptoms.

How people try to cope

Many Americans say they actively practice self-care in everyday life. For example, they describe taking mental health days, protecting personal time, setting boundaries around work and prioritizing rest and leisure.

The problem lies in how they use that leisure time.

Over the past 22 years, the U.S. Bureau of Labor Statistics’ American Time Use Survey has consistently found that watching television is the most popular leisure activity for U.S. adults. Americans spend far more time watching TV than exercising, spending time with friends or practicing reflection through activities like yoga. Other common self-care activities include watching movies and gaming.

Modern leisure time increasingly includes smartphone use. Surveys suggest that mobile phones have become the dominant screen for many Americans, with adults spending several hours per day on their phones.

For many adults, checking social media or watching short videos has become a default relaxation behavior layered on top of traditional screen use. This practice is often referred to as second screening.

Although many people turn to screen-based activities to wind down, these activities may have the opposite effect biologically.

Why modern screen use feels different

Pre-internet forms of leisure often involved activities such as watching scheduled television programs, listening to radio broadcasts or reading books and magazines. For all of these pastimes, the content followed a predictable sequence with natural stopping points.

Today’s digital media environment looks very different. People routinely engage with multiple screens at once, respond to frequent notifications and switch rapidly between several streams of content. These environments continuously require users to split their attention, engage their emotions and make decisions.

This type of mental multitasking draws on the same neural systems people are often attempting to rest with leisure. The result is a far more fragmented and cognitively demanding environment than in the past.

Americans now spend approximately six to seven hours per day on screens across multiple devices. Splitting attention between more than one screen at a time, such as using the phone while watching television, is common. This juggling exposes peoples’ brains to multiple streams of sensory and emotional input simultaneously.

Survey data also suggests that Americans may check their phones roughly 200 times per day. In doing so, they repeatedly pull their attention back to screens during routine moments.

Modern digital platforms are designed to maximize engagement. Algorithms tend to prioritize emotionally arousing content, particularly anger, anxiety and outrage. These feelings drive clicks, sharing and time spent on platforms. Research has shown that this design is associated with higher stress, distraction and cognitive load.

When ‘rest’ doesn’t restore

Against the backdrop of daily hassles and competing demands, it can feel like relief to flip on the TV. Practices such as streaming or so-called bed-rotting – spending extended periods in bed while scrolling – often are framed as a form of radical rest or self-care.

Other common coping behaviors include leaving the television on as background noise, scrolling between tasks throughout the day or using phones during meals and conversations. These strategies can feel restful because they temporarily reduce external demands and decision-making.

However, pairing rest with screen use may undermine the very restoration that people are seeking. Digital media stimulate attention, emotion and sensory processing. Even while people are sitting or lying still, being onscreen can keep their nervous systems in a heightened state of arousal. It may look like downtime, but it doesn’t create the biological conditions for restoration.

How to wind down

Evidence suggests that mental relief comes not from adding new coping strategies, but from reducing the number of demands placed on the brain.

Here are some evidence-based strategies that support genuine restoration:

The goal is to intentionally reduce mental load, not to abandon all digital devices.

To improve well-being in our overstimulated society, it’s important to understand the difference between feeling as though you are unwinding and actually allowing your brain and body to recover. In my view, fewer screens, fewer inputs, fewer emotional demands and more protected time for genuine cognitive rest are important components of an effective wellness strategy.

The Conversation

Robin Pickering does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

ref. Why ‘unwinding’ with screens may be making us more stressed – here’s what to try instead – https://theconversation.com/why-unwinding-with-screens-may-be-making-us-more-stressed-heres-what-to-try-instead-272887

Antibiotic resistance could undo a century of medical progress – but four advances are changing the story

Source: The Conversation – USA (3) – By André O. Hudson, Dean of the College of Science, Professor of Biochemistry, Rochester Institute of Technology

Scientists are fighting back against antibiotic resistance with new strategies and tools. wildpixel/iStock via Getty Images Plus

Imagine going to the hospital for a bacterial ear infection and hearing your doctor say, “We’re out of options.” It may sound dramatic, but antibiotic resistance is pushing that scenario closer to becoming reality for an increasing number of people. In 2016, a woman from Nevada died from a bacterial infection that was resistant to all 26 antibiotics that were available in the United States at that time.

The U.S. alone sees more than 2.8 million antibiotic-resistant illnesses each year. Globally, antimicrobial resistance is linked to nearly 5 million deaths annually.

Bacteria naturally evolve in ways that can make the drugs meant to kill them less effective. However, when antibiotics are overused or used improperly in medicine or agriculture, these pressures accelerate the process of resistance.

As resistant bacteria spread, lifesaving treatments face new complications – common infections become harder to treat, and routine surgeries become riskier. Slowing these threats to modern medicine requires not only responsible antibiotic use and good hygiene, but also awareness of how everyday actions influence resistance.

Since the inception of antibiotics in 1910 with the introduction of Salvarsan, a synthetic drug used to treat syphilis, scientists have been sounding the alarm about resistance. As a microbiologist and biochemist who studies antimicrobial resistance, I see four major trends that will shape how we as a society will confront antibiotic resistance in the coming decade.

1. Faster diagnostics are the new front line

For decades, treating bacterial infections has involved a lot of educated guesswork. When a very sick patient arrives at the hospital and clinicians don’t yet know the exact bacteria causing the illness, they often start with a broad-spectrum antibiotic. These drugs kill many different types of bacteria at once, which can be lifesaving — but they also expose a wide range of other bacteria in the body to antibiotics. While some bacteria are killed, the ones that remain continue to multiply and spread resistance genes between different bacterial species. That unnecessary exposure gives harmless or unrelated bacteria a chance to adapt and develop resistance.

In contrast, narrow-spectrum antibiotics target only a small group of bacteria. Clinicians typically prefer these types of antibiotics because they treat the infection without disturbing bacteria that are not involved in the infection. However, it can take several days to identify the exact bacteria causing the infection. During that waiting period, clinicians often feel they have no choice but to start broad-spectrum treatment – especially if the patient is seriously ill.

Close-up of two pill capsules inscribed AOMXY 500 in a blister packet
Amoxicillin is a commonly prescribed broad-spectrum antibiotic.
TEK IMAGE/Science Photo Library via Getty Images

But new technology may fast-track identification of bacterial pathogens, allowing medical tests to be conducted right where the patient is instead of sending samples off-site and waiting a long time for answers. In addition, advances in genomic sequencing, microfluidics and artificial intelligence tools are making it possible to identify bacterial species and effective antibiotics to fight them in hours rather than days. Predictive tools can even anticipate resistance evolution.

For clinicians, better tests could help them make faster diagnoses and more effective treatment plans that won’t exacerbate resistance. For researchers, these tools point to an urgent need to integrate diagnostics with real-time surveillance networks capable of tracking resistance patterns as they emerge.

Diagnostics alone will not solve resistance, but they provide the precision, speed and early warning needed to stay ahead.

2. Expanding beyond traditional antibiotics

Antibiotics transformed medicine in the 20th century, but relying on them alone won’t carry humanity through the 21st. The pipeline of new antibiotics remains distressingly thin, and most drugs currently in development are structurally similar to existing antibiotics, potentially limiting their effectiveness.

To stay ahead, researchers are investing in nontraditional therapies, many of which work in fundamentally different ways than standard antibiotics.

One promising direction is bacteriophage therapy, which uses viruses that specifically infect and kill harmful bacteria. Others are exploring microbiome-based therapies that restore healthy bacterial communities to crowd out pathogens.

Researchers are also developing CRISPR-based antimicrobials, using gene-editing tools to precisely disable resistance genes. New compounds like antimicrobial peptides, which puncture the membranes of bacteria to kill them, show promise as next-generation drugs. Meanwhile, scientists are designing nanoparticle delivery systems to transport antimicrobials directly to infection sites with fewer side effects.

Beyond medicine, scientists are examining ecological interventions to reduce the movement of resistance genes through soil, wastewater and plastics, as well as through waterways and key environmental reservoirs.

Many of these options remain early-stage, and bacteria may eventually evolve around them. But these innovations reflect a powerful shift: Instead of betting on discovering a single antibiotic to address resistance, researchers are building a more diverse and resilient tool kit to fight antibiotic-resistant pathogenic bacteria.

3. Antimicrobial resistance outside hospitals

Antibiotic resistance doesn’t only spread in hospitals. It moves through people, wildlife, crops, wastewater, soil and global trade networks. This broader perspective that takes the principles of One Health into account is essential for understanding how resistance genes travel through ecosystems.

Researchers are increasingly recognizing environmental and agricultural factors as major drivers of resistance, on par with misuse of antibiotics in the clinic. These include how antibiotics used in animal agriculture can create resistant bacteria that spread to people; how resistance genes in wastewater can survive treatment systems and enter rivers and soil; and how farms, sewage plants and other environmental hot spots become hubs where resistance spreads quickly. Even global travel accelerates the movement of resistant bacteria across continents within hours.

Antibiotic misuse in agriculture is a significant contributor to antibiotic resistance.

Together, these forces show that antibiotic resistance isn’t just an issue for hospitals – it’s an ecological and societal problem. For researchers, this means designing solutions that cross disciplines, integrating microbiology, ecology, engineering, agriculture and public health.

4. Policies on what treatments exist in the future

Drug companies lose money developing new antibiotics. Because new antibiotics are used sparingly in order to preserve their effectiveness, companies often sell too few doses to recoup development costs even after the Food and Drug Administration approves the drugs. Several antibiotic companies have gone bankrupt for this reason.

To encourage antibiotic innovation, the U.S. is considering major policy changes like the PASTEUR Act. This bipartisan bill proposes creating a subscription-style payment model that would allow the federal government up to US$3 billion to pay drug manufacturers over five to 10 years for access to critical antibiotics instead of paying per pill.

Global health organizations, including Médecins Sans Frontières (Doctors Without Borders), caution that the bill should include stronger commitments to stewardship and equitable access.

Still, the bill represents one of the most significant policy proposals related to antimicrobial resistance in U.S. history and could determine what antibiotics exist in the future.

The future of antibiotic resistance

Antibiotic resistance is sometimes framed as an inevitable catastrophe. But I believe the reality is more hopeful: Society is entering an era of smarter diagnostics, innovative therapies, ecosystem-level strategies and policy reforms aimed at rebuilding the antibiotic pipeline in addition to addressing stewardship.

For the public, this means better tools and stronger systems of protection. For researchers and policymakers, it means collaborating in new ways.

The question now isn’t whether there are solutions to antibiotic resistance – it’s whether society will act fast enough to use them.

The Conversation

André O. Hudson, PhD. receives funding from the National Institutes of Health and the National Science Foundation.

ref. Antibiotic resistance could undo a century of medical progress – but four advances are changing the story – https://theconversation.com/antibiotic-resistance-could-undo-a-century-of-medical-progress-but-four-advances-are-changing-the-story-269860

Taxe Gafam : le Conseil constitutionnel consacre un régime fiscal spécifique pour les plateformes numériques

Source: The Conversation – France (in French) – By Grégoire Rota-Graziosi, Professeur CERDI-UCA-CNRS-IRD, Université Clermont Auvergne (UCA)

Le Conseil constitutionnel français admet qu’une activité numérique relève du champ de l’impôt taxé dans la juridiction des utilisateurs. ToninT/Shutterstock

Le 12 septembre 2025, le Conseil constitutionnel français approuve une taxe sur les services numériques (TSN). Il assume l’existence d’un régime fiscal distinct applicable aux grandes plateformes numériques, sans rupture d’égalité devant l’impôt. Une révolution copernicienne ? Oui, car l’impôt n’est plus fondé sur la localisation des entreprises, mais sur celle de ses utilisateurs. En l’occurrence, en France et non aux États-Unis.


Un clic à Paris. Une réservation à Milan. Une vidéo à Londres. Trois gestes anodins, trois fractions de seconde offertes aux plateformes. Pour les marchés financiers, ces actes valent des milliards. Pour les administrations fiscales, ils ne valaient presque rien, les entreprises concernées évitant l’imposition de leurs bénéfices respectifs par des pratiques d’optimisation fiscale.

Pour y remédier, les autorités françaises ont introduit une taxe sur les services numériques (TSN) en 2019 comme une mesure transitoire pour appréhender les bénéfices réalisés en France par les entreprises multinationales dites du « numérique ». Elle rapporterait environ 700 millions d’euros en 2024.

Cette taxe initialement de 3 % s’applique sur le chiffre d’affaires des plateformes de services numériques – intermédiation, publicité ciblée, vente de données, etc.

Comment fonctionne concrètement cette taxe Gafam ? Quelles implications sur notre économie ? Pourquoi

Seule la juridiction des utilisateurs compte

Le 12 septembre 2025, le Conseil constitutionnel admet qu’une activité purement numérique – l’interaction entre une plateforme et ses utilisateurs situés en France – relève du champ de l’impôt. L’absence d’un établissement stable – usine, bureau ou filiale – ne fait plus obstacle à l’imposition des revenus issus d’utilisateurs localisés en France. Cette décision consacre une évolution majeure : une activité immatérielle est localisée par ses utilisateurs justifiant son imposition par la juridiction (pays) de ces derniers.

En reconnaissant ce principe, le Conseil donne un socle constitutionnel à la taxe sur les services numériques (TSN) française et, au-delà, à une fiscalité de l’usage. La présence économique ne se mesure plus en mètres carrés, en nombre de salariés, en valeur des immobilisations corporelles mais en interactions, en données et en attention des utilisateurs.

Cette décision considère l’activité numérique des utilisateurs comme une base fiscale autonome. Elle constitue une rupture discrète, mais historique, dans un débat planétaire portant sur la source de valeur à l’ère numérique.

Les États-Unis vent debout contre cette réforme

Le retrait des États-Unis en janvier 2025 du Global Tax Deal a ravivé la pertinence de solutions unilatérales.

Le 2 décembre 2019, les États-Unis avaient rapidement réagi à l’adoption par la France, en juillet de la même année, de la loi créant la taxe sur les services numériques, en menaçant de rétorsion tarifaire non seulement la France, mais aussi d’autres pays ayant adopté une taxe similaire, comme le Royaume-Uni, l’Espagne, l’Autriche et l’Italie.

L’Organisation de coopération et de développement économiques (OCDE) est alors chargée de trouver une solution multilatérale dans le cadre des règles globales anti-érosion de la base imposable. La solution proposée repose sur deux piliers :

  • La (ré)allocation d’une partie des profits résiduels des grandes multinationales, en particulier numériques, vers les juridictions de marché indépendamment de la présence physique ;

  • L’instauration d’un impôt minimum mondial sur les sociétés, afin de limiter la concurrence fiscale et l’érosion des bases. L’administration de Donald Trump a rejeté en janvier 2025 cette solution et leurs engagements antérieurs dans l’accord de l’OCDE datant de 2021.

Dans ce contexte, la décision du Conseil constitutionnel rapproche la France de la position des Nations unies, sans rompre avec celle de l’OCDE. Dès 2021, l’article 12B du Modèle de Convention fiscale de l’ONU autorise les États à imposer les revenus tirés des « services automatisés fournis à distance », comme le cloud, le streaming, les logiciels, la publicité en ligne, les moteurs de recherche ou les plateformes. Cette approche protège davantage les intérêts des pays du Sud, davantage de consommateurs de services numériques que les « producteurs » de ceux-ci ou les hébergeurs des sièges des entreprises multinationales du numérique.

« Servicisation numérique »

La définition de l’assiette taxable des services numériques est sensiblement plus large dans l’approche des Nations unies que dans les législations fiscales européennes.

L’intérêt de cette définition étendue est d’anticiper les évolutions industrielles actuelles et futures comme la « servicisation numérique ». Cette dernière désigne le passage de la vente de produits physiques à celle de services numériques. Par exemple, la valeur d’un équipement industriel ne repose pas tant sur celle de l’équipement physique que sur les services numériques dédiés à la performance de l’équipement.

La « servicisation numérique » transfère la création de valeur et de profits d’actifs physiques vers des actifs intangibles, comme des droits de propriété intellectuelle ou des services numériques. Le transfert des bénéfices vers des centres étrangers de services numériques localisés dans des pays à faible fiscalité participe à l’érosion des bénéfices imposables.

La taxe sur les services numériques (TSN) devient un moyen de limiter le risque de transfert de profits qui concerne la plupart des secteurs économiques.

Taxation optimale

Par sa forme, la taxe sur les services numériques est simple. Elle repose sur le chiffre d’affaires réalisé dans le pays où habite l’utilisateur. Cette forme évite la renégociation des conventions fiscales bilatérales.

Elle reste critiquée par les partisans de la théorie de la taxation optimale. Pourquoi ? Parce qu’elle réduit l’efficience de la production en taxant chaque transaction, en ignorant les marges bénéficiaires qui varient d’une entreprise à l’autre.

Par exemple, une taxe de 3 % sur le chiffre d’affaires d’une entreprise ayant une marge de 30 % correspond à une taxe de 10 % sur ses bénéfices. La même taxe appliquée à une entreprise moins profitable, ayant une marge de 5 % par exemple, supporterait alors une taxe de 60 % sur ses bénéfices.

Présence économique significative indienne

Son alternative est la présence économique significative (PES) introduite en Inde en 2018, puis au Nigeria notamment.

Ce régime taxe le profit supposé réalisé dans le pays. Si cette forme de taxation respecte davantage l’orthodoxie fiscale en taxant les bénéfices, elle est plus complexe à mettre en œuvre. Elle nécessite d’estimer non seulement le chiffre d’affaires réalisé dans le pays, mais également les coûts associés à l’activité dans le pays concerné.

L’article 12B du Modèle de Convention fiscale de l’ONU laisse le choix aux pays de taxer le chiffre d’affaires ou le profit.

La décision du Conseil constitutionnel a confirmé la compétence fiscale de l’État à taxer la valeur créée par un utilisateur français de services numériques d’entreprises étrangères. Cette décision ne règle pas toutes les difficultés, et de nouveaux défis et oppositions existent concernant la définition ou l’estimation de la valeur taxable.

Elle est pourtant une première étape vers un système fiscal à l’ère du numérique.


Cet article a été co-rédigé avec Abdel-Malek Riad, chercheur associé au CERDI–CNRS et président-directeur général d’AMR IM.

The Conversation

Grégoire Rota-Graziosi est membre de la FERDI. Il est expert en politique fiscales et assure des missions auprès d’institutions nationales, régionales ou internationales.

ref. Taxe Gafam : le Conseil constitutionnel consacre un régime fiscal spécifique pour les plateformes numériques – https://theconversation.com/taxe-gafam-le-conseil-constitutionnel-consacre-un-regime-fiscal-specifique-pour-les-plateformes-numeriques-268600

La selección: ser humano es crear

Source: The Conversation – (in Spanish) – By Laura G. de Rivera, Ciencia + Tecnología, The Conversation

WhataWin/Shutterstock

La ciencia no está solo en los laboratorios o en los últimos avances que retratan las publicaciones científicas. También está en casa, en cada cosa que hacemos y cada cosa que somos. Está escondida entre los magistrales acertijos matemáticos de Alicia en el País de las Maravillas o en cómo funciona el cerebro de los pobres universitarios que están de exámenes por estas fechas… pero también en las mediciones del mar en los confines del mundo o en la cantidad de peso que puede aguantar una hiedra –no es un nombre en clave ni una heroína mitológica, es una planta–. Como la del edificio New Court en Cambridge, que tiene 180 años, 10 metros de alto y pesa unas 12 toneladas, sin contar las raíces.

Y los ejemplos son miles. Quizá no sepamos que, cada vez que abrimos Google Maps, el buen funcionamiento del GPS depende directamente de la teoría de la relatividad, igual que las imágenes digitales y los paneles solares funcionan gracias al efecto fotoeléctrico, explicado por Einstein en 1905. Pero, si estamos hartos de tecnología y lo que queremos es entender el mundo natural, sobre todo el marino –que, por cierto, tiene una razón para ser salado–, podemos viajar con los calamares y los tiburones para comprender, en la práctica, cómo funciona y para qué sirve la evolución: cómo algunos peces transformaron sus aletas en patas, cómo se las apañan las ballenas para amamantar en el agua, por qué un tiburón produce a lo largo de su vida más de 300 000 dientes o el sorprendente ecosistema que late en una gota del océano.

Es posible que, al sumergirnos en estos artículos, igual que ocurre cuando nos zambullimos en el mar, se nos pase por la cabeza que la naturaleza es una verdadera obra de arte. Y, como la naturaleza somos todos, tal vez por eso, ciencia, arte y vida van tan de la mano. Más allá de la evidente relación entre ellas, artes y ciencias se necesitan. Cuando personas de distintas disciplinas colaboran, producen interpretaciones más profundas, diversas y sensibles de la realidad. No hay más que ver los primeros mapas del mundo, las láminas de historia natural o las bellas neuronas retratadas por Santiago Ramón y Cajal.

Y es que los seres humanos tenemos tantísimas ganas de inventar y crear que no nos detenemos ante nada: imaginamos palabras, cronopios y mancuspias y echamos mano del humor y el ingenio para sobrellevar con un mínimo de dignidad que el mundo digital nos pudra el cerebro… hasta la inteligencia artificial puede servir para crear bellas obras de literatura interactiva y multimedia.

The Conversation

ref. La selección: ser humano es crear – https://theconversation.com/la-seleccion-ser-humano-es-crear-273725

Les crocodiles, des reptiles loquaces et à l’écoute du monde

Source: The Conversation – in French – By Nicolas Mathevon, Professeur (Neurosciences & bioacoustique – Université de Saint-Etienne, Ecole Pratique des Hautes Etudes – PSL & Institut universitaire de France), Université Jean Monnet, Saint-Étienne

S’ils sont discrets, les crocodiles sont aussi bavards entre eux, et ce, avant même l’éclosion de l’œuf. Nicolas Mathevon/Université Jean-Monnet, Fourni par l’auteur

On l’imagine chasseur solitaire et discret, constamment à l’affût d’une proie. Pourtant, l’armure d’écailles du crocodile dissimule une vie sociale complexe. Tendez l’oreille : le seigneur des fleuves a beaucoup à dire.


Lorsque l’on se représente un crocodile, on pense à un prédateur silencieux, un tronc d’arbre flottant au milieu du fleuve, attendant patiemment qu’une proie s’approche pour faire brusquement claquer ses mâchoires. Cette image, bien que partiellement vraie – il est sagement déconseillé de nager au milieu de crocodiles –, occulte une réalité biologique fascinante : les crocodiliens (crocodiles, alligators, caïmans et gavials) sont les reptiles les plus vocaux et les plus sociaux de la planète.

Ces animaux possèdent un système de communication acoustique sophistiqué et une ouïe d’une finesse redoutable, peut-être hérités de leurs ancêtres communs avec les oiseaux et les dinosaures. Depuis près de trois décennies, notre équipe de recherche en bioacoustique s’attelle à décoder ce qu’ils disent et à comprendre comment ils perçoivent leur environnement sonore. Voici ce que nos études révèlent du monde sonore des crocodiliens.

La première conversation : parler depuis l’œuf

L’histoire acoustique d’un crocodile commence avant sa naissance. Contrairement à la majorité des reptiles qui pondent leurs œufs et les abandonnent, les mères ou les pères crocodiliens montent la garde près du nid. Mais comment savoir quand les petits sont prêts à sortir, enfouis sous des dizaines de centimètres de sable ou de végétation ? Nos recherches ont démontré que les embryons de crocodiles ne sont pas passifs. Lorsqu’ils sont prêts à sortir de l’œuf, après trois mois d’incubation, ils commencent à émettre des vocalisations particulières, appelées cris d’éclosion.

Les cris d’éclosion des petits crocodiles encore dans l’œuf.
Nicolas Mathevon/Université Jean-Monnet, Fourni par l’auteur91,5 ko (download)

Ces sons, audibles à travers la coquille et à l’extérieur du nid, remplissent une double fonction. D’une part, ils s’adressent à la fratrie. Lors d’expériences consistant à émettre des sons depuis un haut-parleur près d’œufs de crocodiles du Nil prêts à éclore, nous avons observé que l’audition de ces cris incite les autres embryons à vocaliser à leur tour et à briser leur coquille. Ce mécanisme permet de synchroniser l’éclosion : toute la nichée va sortir ensemble. Pour des proies aussi vulnérables que des nouveau-nés de quelques dizaines de grammes, c’est une belle stratégie de survie face aux prédateurs.

D’autre part, ces cris sont un signal impérieux pour la mère ou le père. Une femelle crocodile qui monte la garde depuis trois mois réagit immédiatement à l’audition de ces cris d’éclosion : elle se met à creuser le nid avec ses pattes. Sans ce comportement parental en réponse à leur signal sonore, les petits resteraient prisonniers sous terre.

Cependant, la mère ne réagit pas au premier petit bruit venu. Nos expériences sur le crocodile du Nil ont montré que la femelle réagit à des cris isolés par des mouvements de tête, enfouissant son museau dans le sol comme pour en sentir les vibrations, mais elle ne commence à creuser activement que si les cris forment une séquence continue et rythmée. Ceci évite à la femelle d’ouvrir le nid trop tôt pour un seul petit précocement bavard, ce qui mettrait en danger le reste de la couvée.

Le langage des jeunes crocos

Une fois sortis de l’œuf et délicatement transportés à l’eau dans la gueule de leurs parents, les jeunes crocodiliens restent groupés en crèches sous la protection de l’adulte pendant des semaines, voire des mois. Durant cette période, la communication acoustique entre parent et jeunes est vitale.

Le répertoire vocal des juvéniles est structuré autour de deux types de signaux principaux : les cris de contact et les cris de détresse. Le cri de contact est utilisé pour maintenir la cohésion du groupe de jeunes. C’est un son d’intensité assez faible et dont la fréquence varie peu. Le cri de détresse, lui, est émis lorsqu’un jeune est saisi par un prédateur. Il est plus fort et sa fréquence est plus modulée. Il présente souvent une structure acoustique plus chaotique, ce qui le rend un peu rugueux à l’oreille.

La tête d’un jeune crocodile qui dépasse de l’eau
Les jeunes crocodiles s’expriment, soit pour signaler un danger, soit pour maintenir la cohésion du groupe.
Nicolas Mathevon/Université Jean-Monnet, Fourni par l’auteur

La mère sait faire la différence : un cri de contact suscite une simple attention, tandis qu’un cri de détresse déclenche une réaction agressive de défense immédiate. Mais un parent reconnaît-il la voix de ses petits ? Visiblement pas : nos analyses acoustiques des crocodiles du Nil indiquent qu’il n’y a pas de signature vocale chez les nouveau-nés qui permettrait aux parents de les identifier individuellement. En revanche, nous avons découvert que plus le crocodile est petit, plus le cri est aigu. Lors d’expériences réalisées dans la nature, les mères crocodiles du Nil ont réagi plus intensément aux cris les plus aigus. C’est logique : les plus petits sont les plus vulnérables aux prédateurs et nécessitent une protection accrue.

La tête d’un crocodile adulte dépasse de l’eau. Autour d’elle, de très jeunes crocodiles se confondent avec des plantes aquatiques
Les parents, ici une femelle, surveillent leurs jeunes au sein de crèches et restent attentifs à leurs vocalisations.
Nicolas Mathevon/Université Jean-Monnet, Fourni par l’auteur

Une ouïe entre l’eau et l’air

Le crocodile est un animal amphibie, vivant à l’interface entre l’air et l’eau, mondes aux propriétés acoustiques radicalement différentes. Mais son audition est d’abord aérienne. Lorsque le crocodile flotte, immobile, ce qui est sa position favorite pour attendre une proie, ses oreilles se trouvent juste au-dessus de la ligne de flottaison. Si l’animal plonge, une paupière vient protéger l’oreille, et l’on ne sait pas encore si les crocodiles entendent bien sous l’eau.

La tête d’un caïman yacare qui sort de l’eau
Un yacare à l’affut. Ce caïman, comme les autres crocodiliens, garde ses oreilles juste au-dessus de l’eau lorsqu’il s’immerge.
Nicolas Mathevon/Université Jean-Monnet, Fourni par l’auteur

Comment un animal dont la tête est à moitié immergée fait-il pour localiser une proie, un petit ou un rival ? Chez l’humain ou d’autres mammifères et oiseaux, la localisation repose sur deux indices principaux : le son arrive plus vite à l’oreille tournée vers la source et est également plus fort, puisque la tête fait écran. Dans des expériences, nous avons entraîné des crocodiles à se diriger vers des haut-parleurs pour obtenir une récompense, et les résultats montrent qu’ils utilisent également ces deux sources d’information. Pour les sons graves, ils se fient surtout au temps ; pour les aigus, ils utilisent plutôt la différence d’intensité.

Distinguer dans le bruit

Les crocodiliens vivent souvent dans des environnements bruyants. Pour survivre, ils doivent être capables d’isoler un signal pertinent du bruit de fond, mais aussi d’identifier ce qu’ils entendent. Un bruit dans les roseaux est-il une proie ou un congénère ? Au laboratoire, nous avons découvert quel paramètre acoustique ils utilisent pour faire cette distinction. Ce n’est pas la hauteur du son ni son rythme mais l’enveloppe spectrale, c’est-à-dire le timbre du son. C’est exactement le même paramètre que nous, humains, utilisons pour distinguer les voyelles (« a » ou « o ») ou pour reconnaître la voix de quelqu’un au téléphone. Et la catégorisation des sons opérée par les crocodiles n’est pas totalement figée, elle peut être affinée par l’apprentissage, preuve d’une vraie plasticité cognitive.

En particulier, les crocodiles savent reconnaître et sont particulièrement appâtés par les signaux de détresse d’autres animaux. Quand on diffuse des enregistrements de pleurs de bébés humains, bonobos ou chimpanzés à des crocodiles du Nil, les résultats sont frappants : les crocodiles sont très fortement attirés par ces pleurs. Mais pas n’importe comment.

Les humains jugent la détresse d’un bébé principalement à la hauteur de son cri (plus c’est aigu, plus on pense que le bébé exprime de la douleur). Les crocodiles, eux, se basent sur un critère acoustique plus fiable : le chaos, qui se traduit par la rugosité de la voix qui survient lorsque les cordes vocales sont poussées à leurs limites physiques sous l’effet du stress ou de la douleur.

Les crocodiles se sont donc révélés meilleurs que les humains pour évaluer le niveau de détresse des bébés, en particulier des bonobos. Là où nous surestimons la détresse des bonobos à cause de leurs cris suraigus, les crocodiles ne réagissent intensément qu’aux pleurs contenant beaucoup de chaos acoustique, signe d’une véritable urgence, et donc d’une proie vulnérable.

Entre congénère et proie, que privilégier ?

Si les jeunes crocodiliens sont particulièrement bavards, les adultes ne sont pas en reste. Les mères, et les pères pour les espèces où ils s’occupent de leur progéniture, émettent des grognements qui attirent les jeunes. Femelles et mâles adultes rugissent lors des parades nuptiales et pour défendre leur territoire. Lorsqu’ils se sentent menacés, les adultes peuvent souffler de manière bruyante, ce qui passe l’envie de les approcher. On observe cependant de grandes différences dans l’usage des signaux sonores entre les groupes de crocodiliens : si les alligators et les caïmans sont particulièrement vocaux, les autres crocodiles deviennent plus silencieux à l’âge adulte.

Le rugissement d’un caïman noir adulte.
Nicolas Mathevon/Université Jean Monnet, Fourni par l’auteur30,2 ko (download)

Imaginez un jeune crocodile affamé qui entend un congénère l’appeler, mais qui sent en même temps une odeur de viande. Que fait-il ? Nous avons testé ce conflit sensoriel. Les résultats montrent que l’état de satiété modifie la réponse comportementale. Un crocodile rassasié est très attentif aux sons sociaux : il se dirige vers les cris de contact de ses congénères. Un crocodile affamé privilégie la recherche d’une source de nourriture. Cela suggère une modulation de l’attention : la priorité de l’animal peut basculer selon les besoins physiologiques.

Loin de l’image du monstre primitif, le crocodile est un animal doté d’une vie sensorielle et cognitive riche. Il naît dans un monde sonore, synchronisant son éclosion avec ses frères et sœurs. Il communique avec l’adulte qui s’occupe de lui pour obtenir protection. Il analyse son environnement sonore avec des outils sophistiqués (localisation binaurale, démasquage spatial) dignes des oiseaux ou des mammifères. Il catégorise les sons sur la base de leur timbre pour distinguer les congénères des en-cas. Et il est même capable d’évaluer le niveau de détresse dans la voix d’autres espèces.


Ces études sur les crocodiles ont impliqué de nombreux collaborateurs et collaboratrices, dont Thierry Aubin (CNRS), Nicolas Grimault (CNRS), Nicolas Boyer (Université de Saint-Étienne), Amélie Vergne, Léo Papet, Julie Thévenet et Naïs Caron-Delsbosc. Je remercie les parcs zoologiques La Ferme aux crocodiles (Pierrelatte, France) et Crocoparc (Agadir, Maroc) pour leur soutien.

The Conversation

Nicolas Mathevon ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d’une organisation qui pourrait tirer profit de cet article, et n’a déclaré aucune autre affiliation que son organisme de recherche.

ref. Les crocodiles, des reptiles loquaces et à l’écoute du monde – https://theconversation.com/les-crocodiles-des-reptiles-loquaces-et-a-lecoute-du-monde-271640

Des éclairs détectés sur Mars pour la toute première fois

Source: The Conversation – in French – By Baptiste Chide, Chargé de Recherche CNRS à l’IRAP (Université de Toulouse, CNES), Observatoire Midi-Pyrénées

Pour la première fois, un microphone placé sur le rover Perseverance de la Nasa a permis de découvrir l’existence de petites décharges électriques dans les tourbillons et les tempêtes martiennes de poussière. Longtemps théorisés, ces petits éclairs sur Mars deviennent une réalité grâce à des enregistrements acoustiques et électromagnétiques inédits que nous venons de publier dans la revue Nature. Cette découverte, aux conséquences multiples sur nos connaissances de la chimie et de la physique ainsi que sur le climat de la planète rouge, révèle de nouveaux défis pour les futures missions robotiques et habitées.


Un souffle de vent martien, et soudain, un claquement sec : les dust devils, ces tourbillons de poussière qui parcourent la planète rouge, viennent de nous livrer un secret bien gardé : ils sont traversés de petits arcs électriques ! Ils ont été vus, ou plutôt entendus, de manière totalement fortuite, grâce au microphone de l’instrument SuperCam sur le rover Perseverance qui sillonne Mars depuis 2020.

Ce microphone est notre oreille à la surface de Mars. Il alimente depuis 2021 une « playlist » de plus de 30 heures composée de brefs extraits quotidiens du paysage sonore martien : le microphone est allumé environ 3 minutes tous les deux jours, pour des raisons de partage du temps du rover avec les autres instruments.

Un jackpot scientifique

Parmi ses morceaux les plus écoutés ? Le ronflement basse fréquence du souffle du vent, le crépitement aigu des grains de sable et les grincements mécaniques des articulations du robot. Mais le dernier titre de cette compilation d’un autre monde est une pépite : un dust devil capté en direct alors qu’il passait au-dessus de notre microphone. Qu’un dust devil passe au-dessus de Perseverance, ce n’est pas forcément exceptionnel – ils sont très actifs dans le cratère de Jezero où est posé Perseverance. Mais, qu’il survole le rover à l’instant même où le microphone est allumé, cela relève du jackpot scientifique.

Le son du tout premier éclair enregistré sur Mars.
NASA/JPL-Caltech/LANL/CNES/CNRS/IRAP, Fourni par l’auteur214 ko (download)

Au cœur de cet enregistrement se cachait un signal fort que nous avons peiné à interpréter. Notre première hypothèse fut celle d’un gros grain de sable ayant impacté la zone proche de la membrane du microphone. Quelques années plus tard, alors que nous assistions à une conférence sur l’électricité atmosphérique, nous avons eu une illumination : s’il y avait des décharges sur Mars, la façon la plus directe de les détecter serait de les écouter parce qu’aucun autre instrument à bord de Perseverance ne permet d’étudier les champs électriques.

Évidemment, l’enregistrement le plus favorable pour vérifier cette hypothèse était précisément celui-ci. Réexaminé à la lumière de cette interprétation, il correspondait bien au signal acoustique d’une décharge électrique. Ce n’était pas tout !

Cette onde de choc était précédée d’un signal étrange qui ne ressemblait pas à quelque chose de naturel mais qui provenait en réalité de l’interférence électromagnétique de la décharge avec l’électronique du microphone. Nous savions que celle-ci était sensible aux ondes parasites, mais nous avons tourné ce petit défaut à notre avantage. Grâce à la combinaison de ces deux signaux, tout était devenu clair : nous avions détecté pour la première fois des arcs électriques sur Mars. Pour en être absolument convaincus, nous avons reproduit ce phénomène en laboratoire à l’aide de la réplique de l’instrument SuperCam et d’une machine de Wimshurst, une expérience historiquement utilisée pour générer des arcs électriques. Les deux signaux – acoustique et électromagnétique – obtenus étaient rigoureusement identiques à ceux enregistrés sur Mars.

En soi, l’existence de ces décharges martiennes n’est pas si surprenante que cela : sur Terre, l’électrification des particules de poussière est bien connue, notamment dans les régions désertiques, mais elle aboutit rarement à des décharges électriques. Sur Mars en revanche, l’atmosphère ténue de CO2 rend ce phénomène beaucoup plus probable, la quantité de charges nécessaire à la formation d’étincelles étant beaucoup plus faible que sur Terre. Cela s’explique par le frottement de minuscules grains de poussière entre eux, qui se chargent en électrons puis libèrent leurs charges sous forme d’arcs électriques longs de quelques centimètres, accompagnés d’ondes de choc audibles. Le vrai changement de paradigme de cette découverte, c’est la fréquence et l’énergie de ces décharges : à peine perceptibles, comparables à une décharge d’électricité lorsqu’on touche une raquette à moustiques, ces étincelles martiennes sont fréquentes, en raison de l’omniprésence de la poussière sur Mars.

Des implications au niveau du climat martien

Ce qui est fascinant, c’est que cette découverte intervient après des décennies de spéculations sur l’activité électrique martienne, touchant une arborescence de phénomènes encore peu ou mal expliqués. Par exemple, l’activité électrique de la poussière a longtemps été suspectée de fournir un moyen très efficace pour soulever la poussière du sol martien. Les champs électriques derrière les arcs électriques entendus sur Mars sont a priori suffisamment forts pour faire léviter la poussière.

En absorbant et en réfléchissant la lumière solaire, la poussière martienne contrôle la température de l’air et intensifie la circulation atmosphérique (les vents). Et parce que les vents contrôlent en retour le soulèvement de la poussière, la boucle de rétroactions poussière-vent-poussière est à l’origine des tempêtes globales qui recouvrent intégralement la planète de poussière tous les 5 ou 6 ans. Vu l’importance de la poussière dans le climat martien, et alors que les meilleurs modèles ne savent pas encore prédire correctement son soulèvement, les forces électrostatiques ne pourront plus être ignorées dans le cycle global de la poussière sur Mars.

Expliquer la disparition du méthane

L’autre sujet qui attire les regards des scientifiques concerne le très controversé méthane martien. La communauté débat depuis plus de vingt ans à son sujet en raison de ses implications potentielles, à savoir une activité géophysique ou biologique éventuelle sur Mars, deux hypothèses fascinantes.

Au-delà du caractère énigmatique de ses détections sporadiques, sa disparition – des centaines de fois plus rapide que ce que prédisent les modèles de chimie atmosphérique les plus sophistiqués – a longtemps laissé les experts circonspects. L’un des mécanismes de destruction du méthane les plus prometteurs, proposé il y a une vingtaine d’années, fait précisément intervenir l’action de champs électriques intenses sur la chimie atmosphérique. En accélérant ions et électrons, ces champs permettent de casser les molécules de méthane, mais surtout celles de la vapeur d’eau, produisant ainsi de puissantes espèces réactives capables de détruire le méthane bien plus efficacement encore.

Qui plus est, la présence d’arcs électriques à l’échelle planétaire pourrait s’avérer déterminante dans la préservation de la matière organique. Des expériences de laboratoire ont montré la destruction brutale de biomarqueurs causée par le recyclage d’espèces chlorées induite par l’activité électrostatique de la poussière.

On le voit, la portée de ces nouveaux sons martiens dépasse largement le seul cadre de la communication grand public. Ils redessinent plusieurs pans de notre compréhension de Mars et ouvrent un nouveau champ d’investigations, qui nécessitera un nombre accru d’observations.

Peut-être lors de futures missions ? L’ESA avait déjà tenté l’expérience – sans succès – avec l’atterrisseur Schiaparelli, qui devait réaliser les premières mesures des champs électriques martiens avant de s’écraser à la surface de la planète. L’exploration future, humaine ou non, se devra de mieux caractériser ces champs pour mieux cerner leurs implications. D’ici là, Perseverance restera l’unique témoin in situ de ce phénomène qui est sans doute loin de nous avoir tout révélé.

The Conversation

Franck Montmessin a reçu des financements de l’ANR et du CNES.

Baptiste Chide ne travaille pas, ne conseille pas, ne possède pas de parts, ne reçoit pas de fonds d’une organisation qui pourrait tirer profit de cet article, et n’a déclaré aucune autre affiliation que son organisme de recherche.

ref. Des éclairs détectés sur Mars pour la toute première fois – https://theconversation.com/des-eclairs-detectes-sur-mars-pour-la-toute-premiere-fois-272864