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October 15, 2025

Climate change divides the innovators from the defenders of the status quo – Europe must decide which it wants to be

Source: The Conversation – UK – By Francesco Grillo, Academic Fellow, Department of Social and Political Sciences, Bocconi University

“The European green deal is something we owe to our children because we do not own this planet.” These words date back to a few days before Christmas 2019. They defined Ursula Von Der Leyen’s first presidency of the European Commission but belong to what now seems like a different era.

Now, six years later, after the COVID-19 pandemic and one (still ongoing) war in Europe, what is left of the European green deal? How can we fix what does remain of it? And why are European voters suffering “climate fatigue” if climate change is accelerating? These are some of the questions that a forthcoming conference in Venice will try to address.

Acting to ensure the planet is habitable for our children is undoubtedly a moral imperative. However, for the EU it is one that requires at least two distinct (albeit connected) strategies.

The first is reducing greenhouse emissions in Europe. The second is convincing the rest of the world to do something with the 94% of the CO₂ emissions that are produced outside Europe.

The history of the last ten years shows relative success on the former but far less on the latter. This may go some way to explaining why European voters are becoming frustrated – they feel they are doing their part and yet find themselves exposed to a crisis that is largely generated elsewhere.

Since the Paris agreement, which promised net zero CO₂ emissions by 2050, the world has increased its pollution by 10%. In that time, the EU has cut its own by 13%. That said, Europe had started down this path long before it was binded into action by the Paris agreement. It had already cut emissions by 20% between 1990 and 2016.

Much of this progress is due to Europe’s comparatively weak economic growth and the pressure on European industries to avoid the costs of energy imports. According to a recently published paper the EU has done better than anybody else (if we consider the last 25 years) in terms of raising the percentage of energy consumption coming from renewables – even if it lags behind China on electrification.

This is a strong result but the EU has missed a number of important innovation trends that would aid the transition and reshape its economy in the process. China is still the greatest polluter but it is dominating parts of the renewables supply chain.

The EU dominates the ranking when it comes to the share of energy consumption coming from renewables. And yet it is China that dominates the supply of both solar panels and wind turbines.

Climate leadership

More worryingly, the EU has done very little to influence the speed at which the rest of the world is dealing with emissions. It should have made more of its emissions successes as a diplomacy tool to urge others to speed up their own transitions but it continues to struggle to find its place in a rapidly changing world.

Europe has often aligned itself with its greatest ally, the United States – such as in debates around the creation of the fund meant to compensate developing countries for “loss and damages” from climate change.

With the US now disengaging, Europe will be forced to find new partners at the next COP – and it does not appear to have come to terms with this challenge. In a recent example, Wopke Hoekstra, the EU climate commissioner, hit out at China for failing to set sufficiently ambitious climate targets while the EU has failed to set out its own.

Climate change doesn’t divide the world into good and bad – it separates the innovators from the defenders of the status quo. EU policymakers have mistakenly viewed climate change as merely a bill to pay rather than a chance to change. It focuses on regulations that companies and citizens need to comply with rather than the investments needed for creating endogenous industries and technologies.

This approach has backfired. Recent elections appear to have punished green parties and rewarded climate sceptics. However, European climate fatigue is at least not about denying climate change itself so much as questioning the approach being taken. That is something to work with. But Europe needs new ideas – and they may have to come from outside the Brussels bubble.

Francesco Grillo is affiliated with Vision, the think tank.

– ref. Climate change divides the innovators from the defenders of the status quo – Europe must decide which it wants to be – https://theconversation.com/climate-change-divides-the-innovators-from-the-defenders-of-the-status-quo-europe-must-decide-which-it-wants-to-be-267355

October 15, 2025

How Israel’s famed intelligence agencies have always relied on help from their friends

Source: The Conversation – UK – By Aviva Guttmann, Lecturer in Strategy and Intelligence, Aberystwyth University

When Israel launched its attacks on Iran in the early morning of June 13, many news reports marvelled at the quality and ingenuity of its intelligence agencies in enabling the Israel Defense Forces to strike with such precision. But one element was not talked about in any detail: Israel’s network of relationships with other countries’ intelligence agencies and their contribution to these covert operations.

This cooperation, while critical, can come with a price. It inevitably means a degree of reliance on other countries. Intelligence partners can decide to stop cooperation at any point, which would leave Israel vulnerable to geopolitical shifts that could threaten these relationships and limit its striking capacities.

June’s surgical military interventions against Iran concluded a round of successes against its regional foes. These included the pager attack against Hezbollah in Lebanon as well as assassinations of top Hamas officials, including its political chief Ismail Haniyeh in Iran in July 2024.

All three of Israel’s security agencies were involved: Mossad, Israel’s foreign intelligence agency; Shin Bet, its domestic intelligence agency; and Aman, Israel’s military intelligence division.

Media reports from specialist journalists have revealed some impressive technological advancements. These included using artificial intelligence (AI) to sift through and connect millions of data points to determine targets. Israeli intelligence analysts also used spyware to hack into the phones of the bodyguards of Iranian leaders.

Aman and Mossad have also been adept at recruiting commandos from within local opposition groups. It used these to knock out Iranian air defence installations in the early hours of the first day of the attack.

Israel’s intelligence services are also very good at letting people know just how accomplished they are. It all burnishes their reputation. But much of the time those accomplishments are earned with the help of intelligence from friendly services.

This is nothing new, as I discovered while researching my recent book about Operation Wrath of God. This was the campaign of retribution that followed the Black September murder of members of the Israeli Olympics team at the 1972 summer games in Munich.

While searching the Swiss national archives, I found a large cache of encrypted telegrams that had been shared in a network called Kilowatt. This network involved 18 countries and shared information such as the movements of specific Palestinian people identified as terrorists, including the safe houses and vehicles they used.

Mossad was part of Kilowatt and could use the intelligence it received from European partners to plan and carry out its targeted assassinations in Europe. There is also ample evidence in the cables that western governments knew what Mossad was using the intelligence for.

Israel’s global net of spy friends

The US has historically always been one of the closest intelligence partners of Israeli intelligence. According to studies by the Israeli investigative journalist Ronen Bergman and the American journalist Jefferson Morley, an expert on the CIA, this intelligence-sharing liaison dates back to the early 1950s.

There are numerous cases of Israel calling on US assistance in carrying out targeted assassinations. This relationship endures to this day. Most recently, immediately after the October 7 Hamas attack on Israel, US intelligence dispatched a special unit to assist the IDF in the war in Gaza and established intelligence-sharing channels with Israel to help locate top Hamas commanders.

Black and white image of three Israeli military officers in uniform. — Mossad spy chief Meir Dagan (centre), photographed during the 1982 Lebanon war. Dagan went on to run Mossad from 2002 to 2011.
IDF Spokesperson’s Unit, CC BY-ND

Mossad has also worked with Arab intelligence agencies over the years. Meir Dagan, the director of Mossad from 2002 to 2011, set up a highly effective regional spy network during his tenure. Bergman has documented how this network enabled Israeli intelligence to significantly extend its operational reach. This enabled Mossad and Aman to identify, track and strike at targets in Lebanon and Syria.

These relationships operate despite Arab countries often outwardly condemning the actions of Israeli governments at the UN. For example, the Washington Post recently reported Arab states actually expanded their security and intelligence cooperation with Israel.

While talking about “genocide” in Gaza, countries such as Bahrain, Egypt, Jordan, Qatar, Saudi Arabia and the UAE were sharing data. This relationship also involved cooperation with the Five Eyes intelligence partnership of the US, UK, Australia, Canada and New Zealand.

According to documents obtained by journalists, the partnership, which was named the “Regional Security Construct” by the US, began in 2022 and continued even after Israel began its military operation in Gaza. But Israel’s strike on Qatar in early September, in an attempt to kill senior Hamas representatives meeting there, threatened to disrupt the partnership.

It is thought that anger from Gulf states after the attack was a key factor in focusing US pressure on Israel to agree to make a deal in Gaza. Cooperating to combat the regional threat from Iran is clearly one thing. Threatening the security of Qatar, an important player and key US ally in the Gulf region, is quite another.

Israel’s much-vaunted intelligence capabilities have always relied on some help from its friends. That is unlikely to change. The critical question is the extent to which it can retain the trust of its covert allies. As the past has shown, even in a climate of condemnation and isolation, intelligence cooperation with Israel has remained unaffected.

Strong intelligence connections have often helped overcome moments of crisis. Informal intelligence-sharing arrangements with regional powers, which are kept entirely secret, plausibly denied, and minimally documented, are thus especially crucial now as the region looks to heal its wounds after two years of bitter conflict.

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

– ref. How Israel’s famed intelligence agencies have always relied on help from their friends – https://theconversation.com/how-israels-famed-intelligence-agencies-have-always-relied-on-help-from-their-friends-264818

October 15, 2025

Why higher tariffs on Canadian lumber may not be enough to stimulate long-term investments in US forestry

Source: The Conversation – USA (2) – By Andrew Muhammad, Professor of Agriculture and Resource Economics, University of Tennessee

Canadian lumber waits for shipment in a sawmill’s yard. Andrej Ivanov/Getty Images

Lumber, especially softwood lumber like pine and spruce, is critical to U.S. home construction. Its availability and price directly affect housing costs and broader economic activity in the building sector. The U.S. imports about 40% of the softwood lumber the nation uses each year, more than 80% of that from Canada.

President Donald Trump says that the U.S. has the capacity to meet 95% of softwood lumber demand and directed federal officials to update policies and regulatory guidelines to expand domestic timber harvesting and curb the arrival of foreign lumber.

On Sept. 29, 2025, he announced new tariffs on imported timber and wood products, including an additional 10% tariff on Canadian lumber. Those were added to 35% tariffs imposed on Canadian lumber in August. It was the latest phase in a long-standing dispute over the supply of lumber to builders in the U.S., which dates back to the 1980s, when U.S. producers began arguing that Canadian companies were benefiting from unfair subsidies from their government. Starting on Oct. 15, Canadian softwood lumber imports could face tariffs exceeding 45%.

As researchers studying the forestry sector and international trade, we recognize that the U.S. has ample forest resources. But replacing imports with domestic lumber isn’t as simple as it sounds.

There are differences in tree species and quality, and U.S. lumber often comes at a higher cost, even with tariffs on imports. Challenges like limited labor and manufacturing capacity require long-term investments, which temporary tariffs and uncertain trade policies often fail to encourage. In addition, the amount of lumber imported tends to mirror the boom-and-bust cycles of housing construction, a dynamic that tariffs alone are unlikely to change.

Trump’s moves

To boost U.S. logging, in March, Trump issued an executive order telling the departments of Interior and Agriculture to ease what he called “heavy-handed” regulations on timber harvesting. The executive order and a follow-up memo from Agriculture Secretary Brooke Rollins do not spell out specifics, but officials say more details are in the works that will simplify the timber harvesting process, with the goal of boosting domestic timber production by 25%.

That same month, Trump ordered the Commerce Department to assess how imports of timber, lumber and related wood products affect U.S. national security.

While that assessment was underway, in July, the Commerce Department published findings from a trade review of 2023 Canadian lumber imports. That inquiry alleged that Canadian companies were selling lumber to the U.S. at unfairly low prices, potentially leaving U.S. producers with lower sales or depressed prices. That finding was cited as the basis for the 35% August tariff announcement.

In its national security investigation initiated in March, the Commerce Department concluded that an overreliance on imported wood products means “the United States may be unable to meet demands for wood products that are crucial to the national defense and critical infrastructure.” The September tariff announcement is based on those findings.

Large piles of cut logs are stacked, with homes visible in the distance. — Canadian timber harvesting continues, despite uncertainty about trade with the U.S.
Artur Widak/NurPhoto via Getty Images

Canadian lumber in the US market

In 1991, the U.S. imported 11.5 billion board feet (27 million cubic meters) of Canadian lumber. Those imports rose to a high of 22 billion board feet (52 million cubic meters) by 2005.

But as housing construction declined – especially during the Great Recession from 2007 to 2009 – imports dropped sharply, to less than 8.4 billion board feet (20 million cubic meters) in 2009. The current volume has not recovered to prerecession levels, rising only to 12 billion board feet (28 million cubic meters) in 2024.

The value of Canadian lumber has also fluctuated. Historically, prices for Canadian lumber have averaged about US$330 per thousand board feet ($140 per cubic meter). During and after the COVID-19 pandemic, import prices soared to almost $800 per thousand board feet ($340 per cubic meter). But since peaking in 2021 and 2022, prices have dropped significantly to $436 per thousand board feet ($185 per cubic meter) by 2024.

In total, in 2024, the U.S. imported more than $11 billion in forest and wood products from Canada. Softwood lumber accounted for almost half of that.

Lumber and housing

As personal income rises and populations grow, people seek to build new homes. As new home construction – called “housing starts” in economic data – increases, so does demand for softwood lumber to build those homes. And when housing starts slow, so does lumber demand.

For instance, housing starts fell during the Great Recession. They declined from a January 2006 peak of 2.3 million to less than 500,000 in January 2009 – a decrease of nearly 80%. In that same period, imports of Canadian lumber fell by more than 60%. Domestic softwood lumber production fell by more than 40%.

Both domestic and imported lumber prices can directly influence the overall cost of building homes, which in turn affects housing affordability. That said, lumber used for framing usually accounts for less than 10% of the total cost to build a new home. The effects of tariffs on new home construction may be significantly less than other factors, such as rising labor costs.

There are different kinds of wood commonly used in building lumber.

A matter of choice

The U.S. has a lot of potential lumber available. Especially in the South, the inventory of harvestable lumber has grown significantly over many years.

However, the types of wood available in the U.S. are not always the same as what’s available from Canadian imports. For framing, contractors may prefer spruce, northern pines and fir, naturally abundant in Canada, because they are lighter and less likely to warp than southern yellow pine, which is abundant in the southern U.S. Southern yellow pine is more commonly used to make utility poles and preservative-treated lumber for outdoor construction projects, such as decks.

Lumber from Idaho, eastern Oregon and eastern Washington, however, does share characteristics with Canadian species and could take the place of at least some Canadian lumber.

As the Trump administration seeks to boost domestic lumber, buyers will be looking not only at where their lumber came from, but what it costs and what type of lumber is best for what they need to accomplish.

Andrew Muhammad received funding from the U.S. Department of Agriculture to research timber demand in Vietnam.

Adam Taylor 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 higher tariffs on Canadian lumber may not be enough to stimulate long-term investments in US forestry – https://theconversation.com/why-higher-tariffs-on-canadian-lumber-may-not-be-enough-to-stimulate-long-term-investments-in-us-forestry-265713

October 15, 2025

Erie Canal’s 200th anniversary: How a technological marvel for trade changed the environment forever

Source: The Conversation – USA (2) – By Christine Keiner, Chair, Department of Science, Technology, and Society, Rochester Institute of Technology

A scene on the Erie Canal painted in 1842, two decades after the canal opened. Bettmann/Getty Images

If you visit the Erie Canal today, you’ll find a tranquil waterway and trail that pass through charming towns and forests, a place where hikers, cyclists, kayakers, bird-watchers and other visitors seek to enjoy nature and escape the pressures of modern life.

However, relaxation and scenic beauty had nothing to do with the origins of this waterway.

When the Erie Canal opened 200 years ago, on Oct. 26, 1825, the route was dotted with decaying trees left by construction that had cut through more than 360 miles of forests and fields, and life quickly sped up.

Mules on the towpath along the canal could pull a heavy barge at a clip of 4 miles per hour – far faster than the job of dragging wagons over primitive roads. Boats rushed goods and people between the Great Lakes heartland and the port of New York City in days rather than weeks. Freight costs fell by 90%.

A map shows the canal's route through New York, from Albany to Buffalo. — An 1840 map of the Erie Canal.
New York State/Wikimedia

As many books have proclaimed, the Erie Canal’s opening in 1825 solidified New York’s reputation as the Empire State. It also transformed the surrounding environment and forever changed the ecology of the Hudson River and the lower Great Lakes.

For environmental historians like me, the canal’s bicentennial provides an opportunity to reflect upon its complex legacies, including the evolution of U.S. efforts to balance economic progress and ecological costs.

Human and natural communities ruptured

The Haudenosaunee Confederacy, the Indigenous nations that the French called the Iroquois, engaged in canoe-based trade throughout the Great Lakes and Hudson River valley for centuries. In the 1700s, that began to change as American colonists took the land through brutal warfare, inequitable treaties and exploitative policies.

That Haudenosaunee dispossession made the Erie Canal possible.

Haiwhagai’i Jake Edwards of the Onondaga Nation describes the Erie Canal’s impact on the people of the Haudenosaunee Confederacy. WMHT.

After the Revolutionary War, commercial enthusiasm for a direct waterborne route to the West intensified. Canal supporters identified the break in the Appalachian Mountains at the junction of the Mohawk River and the Hudson as a propitious place to dig a channel to Lake Erie.

Yet cutting a 363-mile-long waterway through New York’s uneven terrain posed formidable challenges. Because the landscape rises 571 feet between Albany and Buffalo, a canal would require multiple locks to raise and lower boats.

Men work on a wooden structure over a narrow canal. — An 1839 view looking eastward from the top lock at Lockport, N.Y., where a series of five locks raised the Erie Canal about 60 feet.
Hulton Archive/Getty Images

Federal officials refused to finance such “internal improvements.” But New York politician DeWitt Clinton was determined to complete the project, even if it meant using only state funds. Critics mocked the $7 million megaproject, worth around US$170 million today, calling it “DeWitt’s Ditch” and “Clinton’s Folly.” In 1817, however, thousands of men began digging the 4-foot-deep channel using hand shovels and pickaxes.

The construction work produced engineering breakthroughs, such as hydraulic cement made from local materials and locks that lifted the canal’s water level about 60 feet at Lockport, yet it obliterated acres of wetlands and forests.

After riding a canal boat between Utica and Syracuse, the writer Nathaniel Hawthorne described the surroundings in 1835 as “now decayed and death-struck.”

However, most canalgoers viewed the waterway as a beacon of progress. As a trade artery, it made New York City the nation’s financial center. As a people mover, it fueled religious revivals, social reform movements and the growth of Great Lakes cities.

A person in a horse-drawn buggy rides over a bridge crossing the Erie Canal in downtown Syracuse. Barges are moored along the edge. — Barges on the Erie Canal in Syracuse around 1900, before the canal’s commerce through the city was rerouted and stretches of it through downtown were filled in and paved. Its path is now Erie Boulevard.
Detroit Publishing Company/Library of Congress

The Erie Canal’s socioeconomic benefits came with more environmental costs: The passageway enabled organisms from faraway places to reach lakes and rivers that had been isolated since the end of the last ice age.

An invasive species expressway

On Oct. 26, 1825, Gov. Clinton led a flotilla aboard the Seneca Chief from Buffalo to New York City that culminated in a grandiose ceremony.

To symbolize the global connections made possible by the new canal, participants poured water from Lake Erie and rivers around the world into the Atlantic at Sandy Hook, a sand spit off New Jersey at the entrance to New York Harbor. Observers at the time described the ritual of “commingling the waters of the Lakes with the Ocean” in matrimonial terms.

Animae — An artist’s image of DeWitt Clinton mingling the waters of Lake Erie with the Atlantic after officially opening the canal in 1825.
Philip Meeder, wood-engraver, 1826, New York Public Library via Wikimedia Commons

Clinton was an accomplished naturalist who had researched the canal route’s geology, birds and fish. He even predicted that the waterway would “bring the western fishes into the eastern waters.”

Biologists today would consider the “Wedding of the Waters” event a biosecurity risk.

The Erie Canal and its adjacent feeder rivers and reservoirs likely enabled two voracious nonnative species, the Atlantic sea lamprey and alewife, to enter the Great Lakes ecosystem. By preying on lake trout and other highly valued native fish, these invaders devastated the lakes’ commercial fisheries. The harvest dropped by a stunning 98% from the previous average by the early 1960s.

The mouth of a sea lamprey — Sea lampreys – eel-like creatures with mouths like suction cups – cut the lake trout population by 98%, and most of the fish that survived had lamprey marks on them. These invasive species began appearing in the Great Lakes after the Erie Canal opened.
T. Lawrence/NOAA Great Lakes, CC BY-SA

Tracing their origins is tricky, but historical, ecological and genetic data suggest that sea lampreys and alewives entered Lake Ontario via the Erie Canal during the 1860s. Later improvements to the Welland Canal in Canada enabled them to reach the upper Great Lakes by the 1930s.

Protecting the $5 billion Great Lakes fishery from these invasive organisms requires constant work and consistent funding. In particular, applying pesticides and other techniques to control lamprey populations costs around $20 million per year.

The invasive species that has inflicted the most environmental and economic harm on the Great Lakes is the zebra mussel. Zebra mussels traveled from Eurasia via the ballast water of transoceanic ships using the St. Lawrence Seaway during the 1980s. The Erie Canal then became a “mussel expressway” to the Hudson River.

The hungry invading mussels caused a nearly tenfold reduction of phytoplankton, the primary food of many species of the Hudson River ecosystem. This competition for food, along with pollution and habitat degradation, led to the disappearance of two common species of the Hudson’s native pearly mussels.

A section of canal covered in green plants — Dense mats of water chestnut infesting the western end of the Erie Canal in 2010. The weeds cut off sunlight for aquatic plants and impede fish movement, and they must be mechanically removed.
U.S. Fish and Wildlife Service

Today, the Erie Canal remains vulnerable to invasive plants, such as water chestnut and hydrilla, and invasive animals such as round goby. Boaters, kayakers and anglers can help reduce bioinvasions by cleaning, draining and drying their equipment after each use to avoid carrying invasive species to new locations.

A recreational treasure

During the Gilded Age in the late 1800s, the Erie Canal sparked a utilitarian sense of environmental concern. Timber cutting in the Adirondack Mountains was causing so much erosion that the eastern canal’s feeder rivers were filling up with silt.

To protect these waterways, New York created Adirondack Park in 1892. Covering 6 million acres, the park balances forest preservation, recreation and commercial use on a unique mix of public and private lands.

Erie Canal shipping declined during the 20th century with the opening of the deeper and wider St. Lawrence Seaway and competition from rail and highways. The canal still supports commerce, but the Erie Canalway National Heritage Corridor now provides an additional economic engine.

A kayak tour shows how locks operate on the Erie Canal. WMHT Public Media.

In 2024, 3.84 million people used the Erie Canalway Trail for cycling, hiking, kayaking, sightseeing and other adventures. The tourists and day-trippers who enjoy the historic landscape generate over $300 million annually.

Over the past 200 years, the Erie Canal has both shaped, and been shaped by, ecological forces and changing socioeconomic priorities. As New York reimagines the canal for its third century, the artificial river’s environmental history provides important insights for designing technological systems that respect human communities and work with nature rather than against it.

Christine Keiner 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. Erie Canal’s 200th anniversary: How a technological marvel for trade changed the environment forever – https://theconversation.com/erie-canals-200th-anniversary-how-a-technological-marvel-for-trade-changed-the-environment-forever-263320

October 15, 2025

Yes, ADHD diagnoses are rising, but that doesn’t mean it’s overdiagnosed

Source: The Conversation – USA (3) – By Carol Mathews, Professor of Psychiatry, University of Florida

Differences in how ADHD is defined explain why the condition is sometimes perceived as overdiagnosed. Catherine Falls Commercial/Moment via Getty Images

Many news outlets have reported an increase – or surge – in attention-deficit/hyperactivity disorder, or ADHD, diagnoses in both children and adults. At the same time, health care providers, teachers and school systems have reported an uptick in requests for ADHD assessments.

These reports have led some experts and parents to wonder whether ADHD is being overdiagnosed and overtreated.

As researchers who have spent our careers studying neurodevelopmental disorders like ADHD, we are concerned that fears about widespread overdiagnosis are misplaced, perhaps based on a fundamental misunderstanding of the condition.

Understanding ADHD as one end of a spectrum

Discussions about overdiagnosis of ADHD imply that you either have it or you don’t.

However, when epidemiologists ask people in the general population about their symptoms of ADHD, some have a few symptoms, some have a moderate level, and a few have lots of symptoms. But there is no clear dividing line between those who are diagnosed with ADHD and those who are not, since ADHD – much like blood pressure – occurs on a spectrum.

Treating mild ADHD is similar to treating mild high blood pressure – it depends on the situation. Care can be helpful when a doctor considers the details of a person’s daily life and how much the symptoms are affecting them.

Not only can ADHD symptoms be very different from person to person, but research shows that ADHD symptoms can change within an individual. For example, symptoms become more severe when the challenges of life increase.

ADHD symptoms fluctuate depending on many factors, including whether the person is at school or home, whether they have had enough sleep, if they are under a great deal of stress or if they are taking medications or other substances. Someone who has mild ADHD may not experience many symptoms while they are on vacation and well rested, for example, but they may have impairing symptoms if they have a demanding job or school schedule and have not gotten enough sleep. These people may need treatment for ADHD in certain situations but may do just fine without treatment in other situations.

This is similar to what is seen in conditions like high blood pressure, which can change from day to day or from month to month, depending on a person’s diet, stress level and many other factors.

Can ADHD symptoms change over time?

ADHD symptoms start in early childhood and typically are at their worst in mid-to late childhood. Thus, the average age of diagnosis is between 9 and 12 years old. This age is also the time when children are transitioning from elementary school to middle school and may also be experiencing changes in their environment that make their symptoms worse.

Classes can be more challenging beginning around fifth grade than in earlier grades. In addition, the transition to middle school typically means that children move from having all their subjects taught by one teacher in a single classroom to having to change classrooms with a different teacher for each class. These changes can exacerbate symptoms that were previously well-controlled.

Symptoms can also wax and wane throughout life. For most people, symptoms improve – but may not completely disappear – after age 25, which is also the time when the brain has typically finished developing.

Psychiatric problems that often co-occur with ADHD, such as anxiety or depression, can worsen ADHD symptoms that are already present. These conditions can also mimic ADHD symptoms, making it difficult to know which to treat. High levels of stress leading to poorer sleep, and increased demands at work or school, can also exacerbate or cause ADHD-like symptoms.

Finally, the use of some substances, such as marijuana or sedatives, can worsen, or even cause, ADHD symptoms. In addition to making symptoms worse in someone who already has an ADHD diagnosis, these factors can also push someone who has mild symptoms into full-blown ADHD, at least for a short time.

The reverse is also true: Symptoms of ADHD can be minimized or reversed in people who do not meet full diagnostic criteria once the external cause is removed.

Kids with ADHD often have overlapping symptoms with anxiety, depression, dyslexia and more.

How prevalence is determined

Clinicians diagnose ADHD based on symptoms of inattention, hyperactivity and impulsivity. To make an ADHD diagnosis in children, six or more symptoms in at least one of these three categories must be present. For adults, five or more symptoms are required, but they must begin in childhood. For all ages, the symptoms must cause serious problems in at least two areas of life, such as home, school or work.

Current estimates show that the strict prevalence of ADHD is about 5% in children. In young adults, the figure drops to 3%, and it is less than 1% after age 60. Researchers use the term “strict prevalence” to mean the percentage of people who meet all of the criteria for ADHD based on epidemiological studies. It is an important number because it provides clinicians and scientists with an estimate on how many people are expected to have ADHD in a given group of people.

In contrast, the “diagnosed prevalence” is the percentage of people who have been diagnosed with ADHD based on real-world assessments by health care professionals. The diagnosed prevalence in the U.S. and Canada ranges from 7.5% to 11.1% in children under age 18. These rates are quite a bit higher than the strict prevalence of 5%.

Some researchers claim that the difference between the diagnosed prevalence and the strict prevalence means that ADHD is overdiagnosed.

We disagree. In clinical practice, the diagnostic rules allow a patient to be diagnosed with ADHD if they have most of the symptoms that cause distress, impairment or both, even when they don’t meet the full criteria. And much evidence shows that increases in the diagnostic prevalence can be attributed to diagnosing milder cases that may have been missed previously. The validity of these mild diagnoses is well-documented.

Consider children who have five inattentive symptoms and five hyperactive-impulsive symptoms. These children would not meet strict diagnostic criteria for ADHD even though they clearly have a lot of ADHD symptoms. But in clinical practice, these children would be diagnosed with ADHD if they had marked distress, disability or both because of their symptoms – in other words, if the symptoms were interfering substantially with their everyday lives.

So it makes sense that the diagnosed prevalence of ADHD is substantially higher than the strict prevalence.

Middle-aged woman sitting at a table and giving a pill to an adolescent girl, who is sipping a glass of water. — A robust body of literature shows the negative outcomes associated with underdiagnosis and undertreatment of ADHD.
SolStock/E+ via Getty Images

Implications for patients, parents and clinicians

People who are concerned about overdiagnosis commonly worry that people are taking medications they don’t need or that they are diverting resources away from those who need it more. Other concerns are that people may experience side effects from the medications, or that they may be stigmatized by a diagnosis.

Those concerns are important. However, there is strong evidence that underdiagnosis and undertreatment of ADHD lead to serious negative outcomes in school, work, mental health and quality of life.

In other words, the risks of not treating ADHD are well-established. In contrast, the potential harms of overdiagnosis remain largely unproven.

It is important to consider how to manage the growing number of milder cases, however. Research suggests that children and adults with less severe ADHD symptoms may benefit less from medication than those with more severe symptoms.

This raises an important question: How much benefit is enough to justify treatment? These are decisions best made in conversations between clinicians, patients and caregivers.

Because ADHD symptoms can shift with age, stress, environment and other life circumstances, treatment needs to be flexible. For some, simple adjustments like classroom seating changes, better sleep or reduced stress may be enough. For others, medication, behavior therapy or a combination of these interventions may be necessary. The key is a personalized approach that adapts as patients’ needs evolve over time.

Carol Mathews receives funding from the National Institutes of Health and the International OCD Foundation. She is affiliated with the International OCD Foundation, and the Family Foundation for OCD Research. She acts as a consultant for the Office of Mental Health for the State of New York.

Stephen V. Faraone receives research funding from the National Institutes of Health, the European Union, the Upstate Foundation and Supernus Pharmaceuticals. With his institution, he holds US patent US20130217707 A1 for the use of sodium-hydrogen exchange inhibitors in the treatment of ADHD. His continuing medical education programs are supported by The Upstate Foundation, Corium Pharmaceuticals, Tris Pharmaceuticals and Supernus Pharmaceuticals. He acts as a consultant to multiple pharmaceutical companies.

– ref. Yes, ADHD diagnoses are rising, but that doesn’t mean it’s overdiagnosed – https://theconversation.com/yes-adhd-diagnoses-are-rising-but-that-doesnt-mean-its-overdiagnosed-257108

October 15, 2025

Focused sound energy holds promise for treating cancer, Alzheimer’s and other diseases

Source: The Conversation – USA (3) – By Richard J. Price, Professor of Biomedical Engineering, University of Virginia

Focused ultrasound directs powerful beams of energy to specific disease targets in the body. Andriy Onufriyenko/Moment via Getty Images

Sound waves at frequencies above the threshold for human hearing are routinely used in medical care. Also known as ultrasound, these sound waves can help clinicians diagnose and monitor disease, and can also provide first glimpses of your newest family members.

And now, patients with conditions ranging from cancer to neurodegenerative diseases like Alzheimer’s may soon benefit from recent advances in this technology.

I am a biomedical engineer who studies how focused ultrasound – the concentration of sound energy into a specific volume – can be fine-tuned to treat various conditions. Over the past few years, this technology has seen significant growth and use in the clinic. And researchers continue to discover new ways to use focused ultrasound to treat disease.

A brief history of focused ultrasound

Ultrasound is generated with a probe containing a material that converts electrical current into vibrations, and vice versa. As ultrasound waves pass through the body, they reflect off the boundaries of different types of tissue. The probe detects these reflections and converts them back into electrical signals that computers can use to create images of those tissues.

Over 80 years ago, scientists found that focusing these ultrasonic waves into a volume about the size of a grain of rice can heat up and destroy brain tissue. This effect is analogous to concentrating sunlight with a magnifying glass to ignite a dry leaf. Early investigators began testing how focused ultrasound could treat neurological disorders, pain and even cancer.

Frontal brain MRI — MRI of a patient treated for essential tremor using focused ultrasound, with the targeted part of the brain circled in red.
Jmarchn/Wikimedia Commons, CC BY-SA

Yet, despite these early findings, technical hurdles stood in the way of applying focused ultrasound in the clinic. For example, because the skull absorbs ultrasound energy, sending focusing beams with high enough energy to reach damaged brain tissue proved difficult. Researchers eventually overcame this problem by integrating large arrays of ultrasound transducers – the probes that convert between electrical signals and vibrations – with image-based information about skull shape and density. This change allowed researchers to better fine-tune the beams to their targets.

It is only after scientists made key advances in imaging technology and acoustic physics in recent years that the promise of ultrasound is being realized in the clinic. Hundreds of clinical trials aimed at treating dozens of conditions have been completed or are ongoing. Researchers have found notable success on a condition called essential tremor, which leads to uncontrolled shaking, usually of the hands. Focused ultrasound treatments for essential tremor are now performed routinely at many locations around the world.

I believe some of the most exciting applications for focused ultrasound include improving drug delivery to the brain, stimulating immune responses against cancer, and treating rare diseases of the central nervous system.

Delivering drugs to the brain

The blood-brain barrier is evolution’s exquisite solution to keeping noxious substances away from this most critical organ. The blood-brain barrier is comprised of very tightly connected cells lining the inside of blood vessels. It only allows certain types of molecules to enter the brain, protecting against pathogens and toxins. However, the blood-brain barrier is problematic when it comes to treating disease because it blocks therapies from reaching their intended target.

More than 20 years ago, pioneering studies determined that sending low-intensity pulses of focused ultrasound could temporarily open the blood-brain barrier by causing microbubbles in blood vessels to oscillate. This oscillation pushes and pulls on the surrounding vessel walls, briefly opening tiny pores that allow drugs in the bloodstream to penetrate into the brain. Critically, the blood-brain barrier opens only where the focused ultrasound is applied.

Focused ultrasound can allow drugs to reach targeted areas of the brain.

After many years of testing the safety of this technique and improving control of ultrasound energy, researchers have developed several devices using focused ultrasound to open the blood-brain barrier for treatment. Clinical trials testing the ability of these devices to deliver drugs to the brain to treat conditions like glioblastoma, brain metastases and Alzheimer’s disease are underway.

In parallel, there has been significant progress in developing gene therapies for numerous brain diseases. Gene therapy involves fixing or replacing faulty genetic material to treat a specific disease. Applying gene therapy to the brain is especially challenging because such therapies typically do not cross the blood-brain barrier.

Animal studies have shown that using focused ultrasound to open the blood-brain barrier can facilitate the delivery of gene therapies to their intended targets in the brain, opening doors to testing this technique in people.

Stimulating immune responses against cancer

Cancer immunotherapy instructs the patient’s own immune system to fight the disease. However, many patients – especially those afflicted with breast cancer, pancreatic cancer and glioblastoma – have tumors that are immunologically “cold,” meaning they are unresponsive to traditional immunotherapies.

Researchers have learned that focused ultrasound can destroy solid tumors in ways that allow the immune system to better recognize and destroy cancer cells. One way focused ultrasound does this is by turning tumors into debris that then literally flows to the lymph nodes. Once immune cells in the lymph nodes encounter this debris, they can initiate an immune response specifically against the cancer.

Inspired by these breakthroughs, the University of Virginia started the world’s first focused ultrasound immuno-oncology center in 2022 to support research in this area and push the most promising approaches to the clinic. For example, my colleagues are running a clinical trial at the center to test the use of focused ultrasound and immunotherapy to treat patients with advanced melanoma.

Treating rare diseases with focused ultrasound

Research on focused ultrasound has primarily focused on the most devastating and prevalent diseases, such as cancer and Alzheimer’s disease. However, I believe that further developments in, and increased use of, focused ultrasound in the clinic will eventually benefit patients with rare diseases.

One rare disease of particular interest for my lab is cerebral cavernous malformation, or CCM. CCMs are lesions in the brain that occur when the cells that make up blood vessels undergo uncontrolled growth. While uncommon, when these lesions grow and hemorrhage, they can cause debilitating neurological symptoms. The most common treatment for CCM is surgical removal of the brain lesions; however, some CCMs are located in brain areas that are difficult to access, creating a risk of side effects. Radiation is another treatment option, but it, too, can lead to serious adverse effects.

We found that using focused ultrasound to open the blood-brain barrier can improve drug delivery to CCMs. Additionally, we also observed that focused ultrasound treatment itself could stop CCMs from growing in mice, even without administering a drug. While we don’t yet understand how focused ultrasound is stabilizing CCMs, abundant research on the safety of using this technique in patients treated for other conditions has allowed neurosurgeons to begin designing clinical trials testing the use of this technique on people with CCM.

With further research and advancements, I am hopeful that focused ultrasound can become a viable treatment option for many devastating rare diseases.

Richard J. Price receives funding from the National Institutes of Health and the UVA Focused Ultrasound Cancer Immunotherapy Center.

– ref. Focused sound energy holds promise for treating cancer, Alzheimer’s and other diseases – https://theconversation.com/focused-sound-energy-holds-promise-for-treating-cancer-alzheimers-and-other-diseases-262622

October 15, 2025

We created an ‘unsexy’ moth that could be the key to greener pest control

Source: The Conversation – UK – By Marie Inger Dam, Researcher, Biotechnology, Lund University

This moth was genetically engineered to be unable to attract a mate. Kristina Brauburger

A single “sexy” gene could help us combat one of the world’s most destructive fruit pests. By deleting the gene that lets female moths produce their mating scent, colleagues and I created an “unsexy” moth – and showed one way to turn insect attraction into a powerful pest control tool.

You’ve probably seen moths flittering around a bright lamppost on a balmy summer night. Those same insects, in their larval form, are the worms that burrow into your apples and peaches, making them serious pests in agriculture.

Moths are usually controlled with chemical pesticides, but pests evolve resistance and these sprays also harm bees and other pollinators. We need new and more sustainable methods to protect important crops targeted by moth larvae, like apples, maize, tomatoes and rice.

In a new study published in the Journal of Chemical Ecology, colleagues and I have demonstrated a way to unravel sexual communication in insects and provide a more sustainable alternative to pesticides. It seems we can stop moths by using their natural instincts against them.

Moths find their mates through chemical communication. Female moths release a species-specific pheromone, which males can detect and follow over long distances.

Farmers have long used synthetic versions of these pheromones to lure male moths away from females so that they don’t reproduce. But the problem is, every species has its own unique blend of pheromones, and replicating the exact recipe in a factory can be costly.

To achieve pheromone-based control on a large-scale, we need to understand how insects make them in the first place – and find the genes responsible.

How we found the sexy gene

Our study focused on the oriental fruit moth (Grapholita molesta), a serious pest on peaches, apples and other fruit. We wanted to identify the gene responsible for making its pheromone.

Pheromones are made from fatty acids by a specific enzyme. To find the genetic material responsible for that enzyme, we needed to identify the fatty acid, the enzyme and eventually the gene.

The fatty acids from which moth pheromones are derived are the same ones that all organisms make in abundance – like the fats in cooking oils and butter.

We first found the small fatty acid that served as the raw material for the moths’ scent, using a technique called gas chromatography, which separates fatty acids based on their size. When we placed this particular fatty acid onto the moth’s pheromone gland, it was converted into the pheromone, confirming we had the right starting point.

Next, we needed to find the exact enzyme that turned that specific fatty acid into that specific pheromone. The key was a double bond between two carbon atoms – that’s a job done by enzymes called desaturases. Searching the moth’s DNA we found many desaturase genes, but only one that was active in females but not in males. This looked like the right gene.

Creating an unsexy moth

Woman using lab equipment — A lab moth being ‘Crispr-ed’ by the author.
Kristina Brauburger

To test the gene’s function, we used Crispr – a precise gene-editing tool sometimes described as “genetic scissors” – to delete the suspected desaturase gene in moth eggs. When the moths grew into adults, females without the gene could no longer produce their pheromone, confirming it as the crucial link in their sexual communication.

Silencing this single gene meant we’d effectively created an “unsexy” moth – one that couldn’t hope to attract a mate. Our method can also be applied to different species, including other pest moths that make similar pheromones.

Pest control with insect genes

Chemical pesticides remain the main defence against crop pests, but resistance is spreading fast and pesticides are linked to soil contamination, pollinator declines and more.

Pheromone-based pest control avoids these problems. When synthetic pheromones are spread in a field or orchard, males become confused because they follow the synthetic trails instead of those made by the female moth, reducing their breeding success.

Our “unsexy” moths helped us identify the exact gene behind this mating signal. Knowing which gene produces the pheromone means we can now reproduce the pheromone outside the insect – for example, by inserting the gene into yeast or plants that act as “biofactories”.

These engineered organisms can then produce the pheromone naturally and cheaply, the same way we use genetically modified yeast to make medicines like insulin.

Our discovery connects lab research to real-world pest management: by decoding the moth’s love signal, we’ve taken a step towards greener, gene-based production of pheromones that could one day replace chemical pesticides.

Marie Inger Dam is a co-inventor on several patent applications relating to pheromone production.

– ref. We created an ‘unsexy’ moth that could be the key to greener pest control – https://theconversation.com/we-created-an-unsexy-moth-that-could-be-the-key-to-greener-pest-control-266312

October 15, 2025

Russie : la logistique de l’ombre contre les sanctions occidentales

Source: The Conversation – in French – By Gilles Paché, Professeur des Universités en Sciences de Gestion, Aix-Marseille Université (AMU)

Les sanctions occidentales poussent la Russie à emprunter des routes alternatives et à exploiter un « marché gris » pour ses approvisionnements. Une nouvelle géographie des échanges se dessine-t-elle ? Est-elle durablement viable ?

Fin septembre 2025, le pétrolier Pushpa (ou Boraçay), battant pavillon béninois, a été arraisonné par des militaires français, puis immobilisé par la justice, au large de Saint-Nazaire (Loire-Atlantique). Parti le 20 septembre du port de Primorsk, en Russie, chargé de 750 000 barils de brut russe, il était attendu à Vadinar, en Inde, trois semaines plus tard. Il apparaît, selon toute vraisemblance, que ce pétrolier fait partie de la « flotte fantôme » utilisée par la Russie pour continuer à commercer avec de nombreux pays en contournant les sanctions auxquelles le pays fait face. Un véritable « jeu du chat et de la souris » dont l’arraisonnement du Pushpa n’est que la partie émergée d’un immense iceberg, avec une totale redistribution des cartes en cours.

En effet, depuis le début de la guerre en Ukraine, le 22 février 2022, les sanctions occidentales contre la Russie bouleversent les routes commerciales traditionnelles, mais aussi les moyens utilisés en vue de les alimenter en biens. Pour Vladimir Poutine, disposer de corridors de transport alternatifs (et d’une « flotte fantôme » efficace) revêt désormais une importance stratégique. Afin de maintenir ses flux d’importation et d’exportation, la Russie explore des voies maritimes et terrestres inédites. Les transformations logistiques à l’œuvre s’inscrivent dans un contexte où les crises géopolitiques et le changement climatique convergent, rendant certaines routes plus accessibles, autant pour la route arctique que pour les corridors eurasiens.

Au-delà des infrastructures visibles, la résilience dont fait preuve la Russie repose sur la mise en œuvre de stratégies informelles et de réseaux parallèles d’approvisionnement, notamment pour les produits énergétiques et industriels. Cette « logistique de l’ombre » illustre la façon dont le pays s’adapte à un environnement international fortement contraint. Si l’impact de la guerre en Ukraine sur l’économie mondiale et les flux transnationaux est encore difficile à mesurer, nul doute qu’une nouvelle géographie émerge.

Force est d’admettre que Vladimir Poutine est en train de gagner la bataille du « contournement logistique » des sanctions, et le monde multipolaire qui va en découler devrait être fort différent de celui des années 2010.

Rupture des routes traditionnelles

Depuis le début de la guerre entre la Russie et l’Ukraine en février 2022, les sanctions occidentales se sont multipliées, affectant plus ou moins fortement les infrastructures logistiques reliant la Russie à ses partenaires commerciaux. En juillet 2025, l’Union européenne a adopté son 18ᵉ paquet de sanctions, visant notamment les réseaux de transport de contournement et les institutions financières facilitant les échanges avec la Russie.

Depuis trois ans, ces mesures ont conduit les armateurs Maersk, MSC et CMA CGM à suspendre leurs rotations vers les ports russes – un retrait qui a plongé de nombreuses entreprises occidentales, des importateurs de composants électroniques aux exportateurs agricoles, dans une grande incertitude. Les flux de matières premières ont été particulièrement perturbés. Le pétrole, le gaz et le charbon, autrefois acheminés via des oléoducs ou les ports baltiques, connaissent désormais des redirections coûteuses.

Ajoutons que les assureurs maritimes occidentaux refusent souvent de couvrir les routes incluant la Russie, même si le club d’assurances « P&I » (Protection & Indemnity), avec American Club, West of England et Gard, l’accepte encore pour le pétrole, des refus qui aggravent les délais et les frais d’assurance pour les entreprises occidentales qui continuent malgré tout à commercer avec le pays, alors qu’elles n’ignorent en rien les risques pris. Dans un monde où pleuvent les embargos, comme en témoigne le cas de la Corée du Nord, la logistique se présente comme un levier stratégique où chaque route bloquée devient un point de tension/pression de nature géopolitique. Une recomposition géographique des flux est en marche, et la Russie en constitue un excellent exemple.

Recomposition géographique des flux

Confrontée aux blocages occidentaux, la Russie s’est tournée vers l’Asie et le Moyen-Orient, des conteneurs arrivant sur son sol depuis la Chine via le Kazakhstan et la mer Caspienne. Ce corridor discret est utilisé pour des biens essentiels comme les composants électroniques. La Turquie joue également un rôle clé par le biais d’entreprises comme Enütek Makina, qui servent d’intermédiaires logistiques pour acheminer par voie maritime (via les ports de Mersin et Izmir) et par voie terrestre (via la Géorgie) des équipements industriels liés au secteur de la défense vers la Russie.

Ceci est d’autant plus vrai que la Route maritime du Nord, qui longe l’Arctique russe depuis la mer de Kara (au nord de la Sibérie occidentale) jusqu’au détroit de Béring (frontière maritime avec l’Alaska), permet à la Russie de relier ses ports arctiques et extrême-orientaux (notamment Mourmansk, Arkhangelsk et Vladivostok) sans dépendre des détroits contrôlés par d’autres puissances. Il est clair qu’il s’agit là d’une alternative stratégique de première importance aux voies plus classiques comme le canal de Suez.

En 2024, le volume de fret transporté le long de cette route par Novatek (exportateur de gaz naturel liquéfié) et Sovcomflot (armateur d’État russe, opérant à l’aide de tankers et méthaniers) vers l’Asie orientale, tout particulièrement la Chine, a atteint un record de près de 38 millions de tonnes, avec 92 voyages autorisés, soit une hausse notable par rapport aux années précédentes. Les infrastructures arctiques, comme les brise-glaces nucléaires, sont renforcées pour accompagner la montée en puissance du trafic sur la Route maritime du Nord, principalement portée par les exportations d’hydrocarbures russes. Ils s’inscrivent dans une logique de souveraineté logistique de la Russie face à un environnement international de plus en plus hostile.

Logistique de l’ombre

La capacité de résistance de la Russie est renforcée par l’existence d’un « marché gris », un phénomène économique connu où des biens légaux sont échangés en dehors des canaux de distribution autorisés. La théorie économique enseigne que ces marchés émergent lorsque des industriels proposent leurs produits à des prix différents selon les marchés, incitant d’autres entreprises à acheter ces produits là où le prix est plus bas pour les revendre discrètement sur des marchés où les clients sont prêts à payer le « prix fort ».

Ce type de commerce parallèle, qui n’a d’ailleurs pas attendu la guerre en Ukraine pour exister, est devenu essentiel afin de maintenir opérationnel l’appareil industriel et militaire russe. Là encore, une logistique de l’ombre joue un rôle clé, notamment avec la fameuse « flotte fantôme », des navires pétroliers hors d’âge et aux propriétaires opaques… dont le Pushpa n’est qu’une pièce modeste de l’échiquier. Le Royaume-Uni a sanctionné 135 de ces tankers en juillet 2025, soulignant leur rôle critique dans le transport illégal de pétrole russe malgré l’embargo. L’Union européenne en a ajouté près de 200 autres à sa liste noire, qui totalise désormais environ 350 navires ciblés. Il n’empêche que la logistique de l’ombre persiste et signe, et si elle n’était pas mise en œuvre, il est fort probable que la Russie ne puisse plus bénéficier de ses cruciales recettes énergétiques.

Comme le soulignent plusieurs ONG, dont Greenpeace et Transport & Environment (T&E), les implications écologiques de l’existence de la flotte fantôme sont préoccupantes. Les navires sont très peu entretenus et responsables d’accidents fréquents. Un cas particulièrement parlant est l’accident impliquant le pétrolier Volgoneft-212 dans le détroit de Kertch, en décembre 2024. Âgé de plus de 50 ans, le navire, qui transportait des produits pétroliers, s’est brisé en deux en pleine tempête, provoquant un déversement massif de fioul dans la mer. En cas d’échouage, les dégâts peuvent également nuire à l’environnement au sens large, comme l’a montré, encore en décembre 2024, la sectionnement de cinq câbles sous marins par un navire de la flotte fantôme en mer Baltique, qui a conduit la Finlande à porter plainte contre le capitaine pour « vandalisme aggravé ».

Une autonomie coûteuse

Au-delà de la résilience, Vladimir Poutine tente sans aucun doute de bâtir une nouvelle souveraineté logistique, fondée sur un investissement massif dans les infrastructures arctiques et le renforcement des liens avec l’Asie centrale et le Moyen-Orient. Une telle diversification relève autant d’une stratégie géopolitique que d’une réponse tactique aux sanctions occidentales, faisant de la logistique un terrain finalement méconnu de reconfiguration du pouvoir.

Il n’empêche que l’autonomie est coûteuse et partielle, car les détours augmentent les coûts, ralentissent les livraisons et fragilisent la fiabilité des approvisionnements. Par exemple, les tarifs de fret pour le transport de pétrole russe depuis le port de Kozmino en Extrême-Orient ont été multipliés par cinq en raison de la pénurie de navires, après que de nouvelles sanctions américaines ont réduit la disponibilité des tankers. En outre, si le marché gris est plus flexible, y recourir expose la Russie à des intermédiaires parfois opportunistes, qui en profitent pour pratiquer des marges excessives.

Nouvelles tensions géopolitiques locales

La stratégie conduite par la Russie depuis trois ans s’inscrit dans une volonté de réduire la dépendance du pays aux routes commerciales traditionnelles, souvent contrôlées par des puissances occidentales. En développant des corridors alternatifs, Vladimir Poutine cherche à sécuriser ses approvisionnements, sachant que les défis sont nombreux, à la fois en matière d’entretien des infrastructures dans des régions reculées et de maîtrise de chaînes logistiques complexes. De plus, la dépendance accrue à des partenaires régionaux entraîne des tensions géopolitiques locales et, par conséquent, une réelle vulnérabilité pour la Russie.

Contrairement à ce que d’aucuns ont cru ou espéré, la guerre en Ukraine n’a pas isolé économiquement et politiquement la Russie. En revanche, elle est en train de transformer en profondeur ses modes d’échange et la logistique qui les soutient. Des chemins de fer les plus discrets aux nouvelles routes océaniques, une nouvelle géographie des flux se dessine, partagée entre légalité et opacité, contrainte et adaptation. L’histoire qui se déroule sous nos yeux rappelle, si besoin était, que dans les crises modernes, quelle que soit leur nature, la logistique est tout à la fois un révélateur, une arme et un lien vital qui sait faire preuve d’une remarquable plasticité.

Gilles Paché 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. Russie : la logistique de l’ombre contre les sanctions occidentales – https://theconversation.com/russie-la-logistique-de-lombre-contre-les-sanctions-occidentales-265044

October 15, 2025

Les « marques de cure-dents » sur les fossiles préhistoriques n’en étaient peut-être pas

Source: The Conversation – France in French (2) – By Ian Towle, Research Fellow in Biological Anthropology, Monash University

Une molaire de Néandertal. Nowaczewska et al., 2021

Une étude sur plus de 500 primates sauvages montre que les « sillons de cure-dents » sur les dents fossiles peuvent se former naturellement, tandis que certaines pathologies modernes, comme les abfractions, sont propres aux humains.

Depuis des décennies, de fines rainures observées sur des dents humaines préhistoriques étaient interprétées comme la preuve d’un geste délibéré : des humains nettoyant leurs dents à l’aide de petits bâtons ou de fibres végétales, ou cherchant à soulager une douleur gingivale. Certains chercheurs y ont même vu la plus vieille habitude humaine.

Mais selon une étude publiée dans l’American Journal of Biological Anthropology, cette hypothèse serait à revoir. Les auteurs ont constaté que ces mêmes stries apparaissent aussi naturellement chez des primates sauvages, sans qu’aucun comportement de curetage dentaire ne soit observé. Encore plus surprenant : l’analyse de plus de 500 primates, appartenant à 27 espèces vivantes ou fossiles, n’a révélé aucune trace d’une maladie dentaire fréquente chez l’humain moderne, les lésions dites d’abfraction – ces entailles profondes en forme de V au niveau de la gencive.

Ces découvertes invitent à repenser l’interprétation des fossiles et ouvrir de nouvelles pistes sur ce qui, dans l’usure et les pathologies de nos dents, témoigne d’une évolution proprement humaine.

Mâchoire d’orang-outan présentant une dentition complète, dont une dent porte une rainure inhabituelle à la base de sa racine — Orang-outan (Pongo pygmaeus) présentant une « marque de cure-dent » sur la deuxième molaire inférieure gauche (spécimen FMNH 19026, Field Museum de Chicago). Une flèche orange indique l’emplacement de la rainure.
Ian Towle

Pourquoi les dents comptent dans l’évolution humaine

Les dents sont la partie la plus résistante du squelette et survivent souvent bien après la décomposition du reste du corps. Les anthropologues s’en servent pour reconstituer les régimes alimentaires, les modes de vie et l’état de santé des populations anciennes.

Même les plus petites marques peuvent avoir une grande signification. L’une des plus fréquentes est une fine rainure qui traverse la racine exposée de certaines dents, souvent entre deux d’entre elles. Depuis le début du XXᵉ siècle, ces traces ont été baptisées « marques de cure-dent » et interprétées comme les signes d’un usage d’outils ou de pratiques d’hygiène dentaire.

On en a signalé tout au long de notre histoire évolutive, sur des fossiles vieux de deux millions d’années jusqu’aux Néandertaliens. Mais jusqu’ici, personne n’avait réellement vérifié si d’autres primates présentaient ces mêmes marques. Une autre affection, appelée abfraction, se manifeste différemment : par des entailles profondes en forme de coin à la base de la gencive. Très fréquentes en dentisterie moderne, elles sont souvent associées au grincement des dents, à un brossage trop vigoureux ou à la consommation de boissons acides. Leur absence sur les fossiles connus intrigue depuis longtemps les chercheurs : les autres primates en sont-ils vraiment exempts ?

Ce que nous avons fait

Pour vérifier ces hypothèses, nous avons analysé plus de 500 dents appartenant à 27 espèces de primates, actuelles et fossiles. L’échantillon comprenait notamment des gorilles, des orang-outans, des macaques, des colobes et plusieurs singes disparus. Fait essentiel, tous les spécimens provenaient de populations sauvages, ce qui signifie que l’usure de leurs dents n’a pas pu être influencée par les brosses à dents, les boissons gazeuses ou les aliments transformés.

Nous avons recherché des lésions cervicales non carieuses – un terme désignant une perte de tissu au niveau du col de la dent qui n’est pas causée par la carie. À l’aide de microscopes, de scanners 3D et de mesures de perte de tissu, nous avons documenté même les plus petites lésions.

Dentitions de primates présentant différents types de pathologies dentaires — Différents types de lésions radiculaires observées chez les primates sauvages, notamment une érosion acide (en haut à gauche) et des sillons présentant des caractéristiques similaires à celles des marques de cure-dents observées sur des fossiles humains.
Ian Towle

Ce que nous avons découvert

Environ 4 % des individus présentaient des lésions. Certaines ressemblaient presque exactement aux classiques « sillons de cure-dents » observés sur les fossiles humains fossiles, avec de fines rayures parallèles et des formes effilées. D’autres lésions étaient peu profondes et lisses, surtout sur les dents de devant, probablement causées par les fruits acides que beaucoup de primates consomment en grande quantité.

Mais une absence nous a frappé. Nous n’avons trouvé aucune lésion par abfraction. Malgré l’étude d’espèces ayant une alimentation extrêmement dure et des forces de mastication puissantes, aucun primate n’a présenté les défauts en forme de coin si couramment observés dans les cliniques dentaires modernes.

Une illustration montrant à quoi ressemblent les lésions par abfraction sur les dents humaines.
Wikimedia, CC BY

Qu’est-ce que cela signifie ?

Premièrement, cela signifie que les sillons ressemblant à des marques de cure-dents ne prouvent pas nécessairement l’utilisation d’outils. La mastication naturelle, les aliments abrasifs, ou même le sable ingéré peuvent produire des motifs similaires. Dans certains cas, des comportements spécialisés, comme arracher de la végétation avec les dents, peuvent également y contribuer. Il faut donc rester prudent avant d’interpréter chaque sillon fossile comme un acte délibéré de curetage dentaire.

Deuxièmement, l’absence totale de lésions par abfraction chez les primates suggère fortement qu’il s’agit d’un problème propre aux humains, lié à nos habitudes modernes. Elles sont beaucoup plus probablement causées par un brossage trop vigoureux, les boissons acides et les régimes alimentaires transformés que par les forces de mastication naturelles. Cela place les abfractions aux côtés d’autres problèmes dentaires, comme les dents de sagesse incluses ou les dents mal alignées, qui sont rares chez les primates sauvages mais fréquents chez l’homme aujourd’hui. Ces observations alimentent un domaine de recherche émergent appelé odontologie évolutive, qui utilise notre passé évolutif pour comprendre les problèmes dentaires actuels.

Pourquoi est-ce important aujourd’hui ?

À première vue, les sillons sur les dents fossiles peuvent sembler anecdotiques. Pourtant, ils ont une importance à la fois pour l’anthropologie et pour la dentisterie. Pour la science évolutive, ils montrent qu’il est essentiel d’observer nos plus proches parents avant de conclure à une explication culturelle spécifique ou unique. Pour la santé moderne, ils mettent en évidence à quel point nos régimes alimentaires et nos modes de vie modifient profondément nos dents, nous distinguant des autres primates.

En comparant les dents humaines à celles des autres primates, il devient possible de distinguer ce qui est universel (l’usure inévitable due à la mastication) de ce qui est propre à l’homme – le résultat des régimes alimentaires, des comportements et des soins dentaires modernes.

Et ensuite ?

Les recherches futures porteront sur des échantillons plus larges de primates, examineront les liens entre régime alimentaire et usure dentaire dans la nature, et utiliseront des techniques d’imagerie avancées pour observer la formation des lésions. L’objectif est d’affiner notre interprétation du passé tout en découvrant de nouvelles façons de prévenir les maladies dentaires aujourd’hui.

Ce qui peut ressembler à un sillon de cure-dents sur une dent humaine fossile pourrait tout aussi bien être un simple sous-produit de la mastication quotidienne. De même, il pourrait refléter d’autres comportements culturels ou alimentaires laissant des marques similaires. Pour démêler ces possibilités, il faut disposer de jeux de données comparatifs beaucoup plus larges sur les lésions des primates sauvages ; ce n’est qu’ainsi que l’on pourra identifier des tendances générales et affiner nos interprétations du registre fossile.

Parallèlement, l’absence de lésions par abfraction chez les primates suggère que certains de nos problèmes dentaires les plus courants sont propres à l’homme. Cela rappelle que même dans quelque chose d’aussi quotidien qu’un mal de dents, notre histoire évolutive est inscrite dans nos dents, mais façonnée autant par nos habitudes modernes que par notre biologie ancienne.

Ian Towle reçoit un financement du Conseil australien de la recherche (Australian Research Council, ARC DP240101081).

– ref. Les « marques de cure-dents » sur les fossiles préhistoriques n’en étaient peut-être pas – https://theconversation.com/les-marques-de-cure-dents-sur-les-fossiles-prehistoriques-nen-etaient-peut-etre-pas-267019

October 15, 2025

Blazars, ces phares cosmiques qui nous guident depuis les tréfonds du cosmos

Source: The Conversation – France in French (2) – By Jonathan Biteau, Maître de conférence en physique des astroparticules, Université Paris-Saclay

Pour se repérer, on peut utiliser les phares… ou les blazars. 500px via Wikimedia, CC BY

Les humains utilisent les astres pour se repérer depuis la nuit des temps. Aujourd’hui, la précision de nos systèmes de géolocalisation dépend des blazars, ces phares cosmiques qui abritent des trous noirs. Découvrons leurs mystères en nous aidant de l’analogie avec les phares qui ponctuent la côte et qui guident les marins dans la nuit.

Depuis la plage du Prat, au cœur de l’île d’Ouessant (Finistère), on aperçoit l’imposant phare du Créac’h au-dessus des flots. Par nuit claire, le phare de Créac’h est visible à plus de 32 milles marins (environ 60 kilomètres). Considéré comme le phare le plus puissant d’Europe, le Créac’h est un guide inestimable pour les équipages des bateaux, suppléant aux systèmes de navigation par satellite utilisés en cabine.

De nos jours, nous utilisons quotidiennement le positionnement par satellite via nos téléphones portables. Cependant, nous oublions souvent que la précision de ces systèmes de localisation repose sur des principes de physique fondamentale et des mesures d’astronomie de pointe.

Dans le passé, les marins utilisaient comme points de référence l’étoile Polaire ou des galaxies proches, telles que les nuages de Magellan situés à quelques centaines de milliers d’années-lumière. Le positionnement des satellites repose quant à lui sur l’utilisation de points lumineux sur la voûte céleste dont la direction est suffisamment stable. Les points de référence les plus stables connus sont des balises cosmiques situées à plusieurs milliards d’années-lumière. Leurs noms ? Les blazars.

Des feux ardents au voisinage des trous noirs

Les théories de la relativité générale et restreinte d’Einstein sont au cœur de notre compréhension des blazars. Le feu d’un phare comme le Créac’h est constitué de puissantes lampes halogènes dont le faisceau est concentré par des lentilles de Fresnel.

Un blazar est quant à lui constitué de deux faisceaux, des jets faits de plasma se déplaçant à plus de 99,5 % de la vitesse de la lumière. Contrairement aux faisceaux de phares, les jets de blazars ne tournent pas : ils restent relativement stables du point de vue de l’observateur.

À l’origine de ces jets se trouve un trou noir des milliers de fois plus massif que celui situé au centre de notre galaxie. C’est la rotation du trou noir sur lui-même et celle du disque de matière l’entourant qui permettent d’injecter de l’énergie dans les jets. La source d’énergie à l’origine de la lumière d’un blazar est donc paradoxalement un trou noir !

schéma et photo du blazar au centre de la galaxie M87 — Illustration des observations des environs du trou noir de la galaxie M 87 à diverses échelles en ondes radio (orange), dans le domaine optique (en haut, à droite), en rayons X (en bleu) et en rayon gamma (graphique en bas, représentant le flux de M 87 en fonction du temps).
EHT Collaboration, Fermi-LAT Collaboration, H.E.S.S. Collaboration, MAGIC Collaboration, VERITAS Collaboration, EAVN Collaboration, CC BY-SA

Ces jets astrophysiques sont observés dans des galaxies proches comme la radiogalaxie Messier 87. Depuis la Terre, les deux jets de cette galaxie sont observés de biais. L’un des deux jets est plus brillant car le plasma qu’il émet a tendance à s’approcher de nous, tandis que le plasma émis par l’autre jet s’éloigne. Plus l’angle entre le faisceau du phare et notre ligne de visée (l’axe entre le phare et l’observateur) est grand, plus la lumière que nous recevons du faisceau est faible. Mais que se passerait-il si l’un des jets était dirigé vers la Terre ? Nous observerions un phare extrêmement lumineux : un blazar. Une radio galaxie comme Messier 87 n’est donc rien d’autre qu’un blazar désaxé.

Un blazar, défini par l’orientation d’un de ses jets vers la Terre, peut ainsi être des dizaines de milliers de fois plus brillant qu’une radio galaxie située à la même distance.

Un faisceau qui produit sa propre lumière

Les lentilles de Fresnel du Créac’h concentrent la lumière de lampes halogènes en faisceaux de photons qui voyagent jusqu’aux équipages marins. Pour les blazars, c’est un plasma de particules énergétiques qui se propagent selon l’axe des jets. Ces particules perdent une partie de leur énergie en émettant de la lumière dans le domaine visible et en ondes radio, par rayonnement synchrotron. C’est ce même rayonnement qui limite les énergies qu’atteignent les accélérateurs de particules construits sur Terre, tel le grand collisionneur de hadrons (LHC) du CERN.

Mais si les pertes synchrotron constituent un facteur limitant pour les ingénieurs de faisceaux de particules terrestres, elles offrent aux astronomes et physiciens des astroparticules une formidable fenêtre d’observation sur des phénomènes naturels autrement plus énergétiques que ceux des accélérateurs artificiels.

Ainsi, les pertes par rayonnement des blazars ne se limitent pas aux ondes radio et à la lumière visible. Elles s’étendent également aux rayons X et aux rayons gamma.

Les rayons gamma les plus énergétiques en provenance de blazars ont été observés à des énergies dix mille milliards de fois supérieures à celle des photons visibles. Les particules qui ont émis ces rayons gamma sont encore plus énergétiques, jusqu’à des millions de fois s’il s’agit de rayons cosmiques de type protons plutôt que d’électrons.

Identifier la nature des particules émettant les rayons gamma des blazars pourrait ainsi éclairer le mystère encore tenace de l’origine des rayons cosmiques et des neutrinos les plus énergétiques que nous observons.

Apercevoir les blazars dans la brume cosmique

Les blazars les plus éloignés émettent depuis une époque correspondant au premier milliard d’années suivant le Big Bang, dans un univers qui soufflera bientôt ses 14 milliards de bougies. La quantité de rayons gamma qui nous parvient des phares lointains est faible, non seulement en raison de leur distance, mais aussi à cause d’une brume un peu particulière qui imprègne même les régions les plus reculées du cosmos.

Par temps brumeux, le phénomène qui limite la portée du Créac’h est la diffusion de la lumière visible par les minuscules gouttelettes d’eau qui composent le brouillard. Le feu du phare, que les marins devraient voir comme une source quasi ponctuelle, apparaît comme une tâche de plus en plus diffuse à mesure qu’ils s’éloignent de la côte.

La portée des blazars émettant les rayons gamma les plus énergétiques est quant à elle limitée par un phénomène de physique des particules : l’annihilation de deux particules de lumière — un photon gamma et un photon de plus faible énergie — en une paire électron-positron. Pour les faisceaux gamma de blazars, la brume est donc faite de lumière !

Illustration de la brume cosmique : les mécanismes d’atténuation du flux d’un blazar par l’interaction entre rayon gamma et photon visible dans les vides cosmiques.
L. Gréaux et J. Biteau, Fourni par l’auteur

Plus l’énergie du rayon gamma est élevée, et plus la distance du blazar qui l’émet est grande, plus l’atténuation du flux reçu est importante. Les photons de faible énergie jouant le rôle de minuscules gouttelettes résultent de l’émission cumulée de toutes les étoiles et galaxies depuis le début de l’univers.

Jusqu’à récemment, la détection de ces « gouttelettes » représentait un véritable défi observationnel. Les trois techniques de mesure connues, dont celle qui exploite l’atténuation des rayons gamma, semblent désormais atteindre des valeurs compatibles entre elles, ouvrant la voie à de nouveaux outils cosmologiques pour répondre au paradoxe d’Olbers ou à la tension de Hubble.

Éruptions de blazars et cours de la Bourse

Les blazars n’ont-ils donc plus aucun mystère pour nous ? Loin de là.

Alors que les phares maritimes clignotent à intervalles réguliers pour permettre aux équipages de les identifier, les blazars brillent de manière erratique, à l’image des cours boursiers fluctuant au fil des ans. Lors des éruptions les plus extrêmes, on a même observé le flux de blazars doubler en quelques minutes seulement ! Comprendre ces éruptions représente encore un défi pour l’astrophysique des hautes énergies et la physique des plasmas.

L’avènement d’observatoires comme le Vera C. Rubin Observatory dans le domaine visible et le Cherenkov Telescope Array Observatory en rayons gamma promet des avancées majeures dans la cartographie des éruptions de blazars. Tout en levant le voile de la brume cosmique, ces observations promettent de mieux comprendre les accélérateurs persistants les plus puissants du cosmos.

Jonathan Biteau a reçu des financements de l’Université Paris-Saclay et de l’Institut Universtaire de France.

– ref. Blazars, ces phares cosmiques qui nous guident depuis les tréfonds du cosmos – https://theconversation.com/blazars-ces-phares-cosmiques-qui-nous-guident-depuis-les-trefonds-du-cosmos-267142