Category: The Conversation

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Pillion: what a sex therapist expert thinks of this domination-themed queer rom-com

Source: The Conversation – UK – By Chantal Gautier, Senior Lecturer in Psychology and Sex and Relationship Therapist, University of Westminster

If you’re looking for a film that’s daring and emotionally layered, then Harry Lighton’s debut feature Pillion absolutely hits the mark. The film follows Colin (Harry Melling), a shy suburban guy stuck in routine and Ray (Alexander Skarsgård), a magnetic unreadable biker whose presence exudes both aloofness and intrigue.

What starts as a rough transactional alleyway hook-up, quickly shifts into a 24/7 BDSM (best understood when read in three pairs: bondage and discipline, domination and submission, sadism and masochism) dynamic built on power, ritual and control.

Within the broader framework of BDSM, Pillion situates Colin and Ray’s dynamic inside the concept of consensual total power exchange: a structured voluntarily arrangement in which a submissive (or “slave”) offers continuous obedience and service to a dominant (or “master”) extending beyond “scenes” and into daily life.

At its core Pillion explores power, eroticism, masculinity and identity. Lighton doesn’t shy away from the erotic elements. In fact, Lighton uses them as a springboard for deeper questions of self-definition. As we witness moments of submission and humiliation rituals (shot with a mix of tension and tenderness), we follow Colin’s emotional journey. From confusion to curiosity and eventually, a sense of charged enjoyment he didn’t expect, Colin finds himself surrendering in ways he never imagined.

The trailer for Pillion.

One of the film’s most memorable sequences places submissives lined up face-down with bare backsides on picnic tables in the middle of a forest. Colin’s despair is unmistakable. It’s in these moments the film’s title snaps into sharp focus, clarifying who leads, who submits, and who rides pillion (the “bottom” in queer discourse).

Lighton solidifies dominant-submissive slave devotion with an unexpected sense of groundedness. The involvement of real-life members of the Gay Bikers Motorcycle Club amplifies the scene’s credibility, giving it a charged, lived-in authenticity.

Beneath the leather mask

But what symbolic or emotional function does control serve for Ray (if there is one, it might simply be this is what Ray is into – what we call their erotic template).

The film offers two compelling possibilities. First, the symbolic elements of BDSM (collars, rituals and rules) create a relationship framework that reaffirms the dominant-submissive bond of unity. For Ray, this connection doesn’t stem from emotional openness but from the stability he maintains through structure and control.

BDSM becomes a space where instructing Colin allows Ray to assert his identity through a style of masculinity that values control. Ray has deliberately curbed his emotional expression. At his core, he is someone who does not allow himself to need. So, for Ray, the dominant-submissive slave dynamic, becomes a mechanism for keeping vulnerability at bay.

Second, research on attachment styles suggest dominance within BDSM can offer the kind of predictability and structure that people with avoidant attachment styles often experience as safe. People like Ray who are uneasy with emotional closeness or unpredictability, may find reassurance in the clearly defined expectations of these dynamics. With emotional disclosure minimised and expectations clarified, the dominant role creates conditions that shield Ray from the forms of vulnerability he finds threatening.

The film’s exploration of masculinity deepens, revealing how societal and cultural norms shape what is considered “manly”. Ray embodies commonly held masculine ideals, including stoicism, self-control, confidence and a sculpted physique. Colin’s more submissive, compliant energy challenges these expectations, revealing masculinity as culturally shaped rather than fixed.

Alexander Skarsgård on Pillion.

Awakening of self

In his “slave” role, Colin embodies both conventional and unconventional masculinity. His surrender emerges as strength – endurance, discipline, sexual stamina. Because submissive roles demand patience, obedience and the resilience to meet discomfort (consensually), they cultivate qualities that expand, rather than diminish, the boundaries of masculinity, providing a more fluid and expansive understanding of masculine identity.

For Colin, the dominant-submissive slave journey becomes a path of self-discovery, allowing him to recognise what he wants, what he excels at – his “aptitude for devotion” – and ultimately who he is. His evolving masculine identity takes shape as he embraces the newly uncovered self, not with shame, but with authenticity.

The film makes clear that BDSM dynamics, despite popular assumptions, are not bound by gender. And while Pillion concentrates on a gay male relationship, the emotional terrain it explores – power, vulnerability and identity – resonate across genders.

Eventually, in pursuit of greater happiness Colin begins to question the arrangement, perhaps prompted by those rare fleeting moments when Ray lets his guard down. Summoning newfound courage, he asks for a “day off” from their daily dominant-submissive dynamic. After a chaotic and rebellious detour, Ray agrees to the new terms. But a question lingers at the film’s emotional core: can Ray allow himself to experience emotional closeness beyond his role as “master”?

Pillion is an emotionally intelligent multi-layered film, rich with moments of humour, wonder and rawness. Boldly provocative it immerses viewers in a world of BDSM, while challenging conventional assumptions about desire, relationships and identity. Lighton delivers a film anchored by exceptional performances from both its main cast and its supporting ensemble, crafting a story that sticks with you long after the credits rolls.

Looking for something good? Cut through the noise with a carefully curated selection of the latest releases, live events and exhibitions, straight to your inbox every fortnight, on Fridays. Sign up here.

The Conversation

Chantal Gautier 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. Pillion: what a sex therapist expert thinks of this domination-themed queer rom-com – https://theconversation.com/pillion-what-a-sex-therapist-expert-thinks-of-this-domination-themed-queer-rom-com-270224

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A brief history of the exposed nipple in fashion – from Marie Antoinette to Sydney Sweeney

Source: The Conversation – UK – By Naomi Braithwaite, Associate Professor in Fashion and Material Culture, Nottingham Trent University

When Hollywood actress Sydney Sweeney attended Variety’s Power of Women event on October 30 in Los Angeles, she may have delivered an empowering and inspirational speech, but it was her dazzling, see-through dress that really stole the show.

The floor-length silver design was a collaborative creation by Christian Cowan and Elias Matso. It was made from crystal mesh and structured around a steel-bone corset. The sheerness of the fabric meant her nipples were visible – a detail that stirred a frenzy of media attention across the globe.

Many people have marvelled at the dress, with an X user calling it an “absolute showstopper”. Sweeney’s bold choice to go braless sparked debates on social media around image and empowerment. But there has also been a backlash, criticising her for wearing such a revealing dress at an event that celebrates female advocacy and achievements.

Sweeney wearing the dress as she is recognised at the Variety Power of Women event.

Since 2012, the Free the Nipple movement has campaigned for gender equality for women by highlighting that while men can go topless in public, in many countries women could be arrested for indecent exposure.

Over the years the movement has gained momentum with the intention of showing that it is not just about nudity, but – importantly – about how women present their bodies and are perceived by others.

Critiques of Sweeney’s dress, however, demonstrate that the visible nipple still causes controversy. At the Brit Awards in March 2025, musician Charli XCX’s sheer outfit and visible nipples led to hundreds of complaints to Ofcom. A recent 2025 survey by YouGov, meanwhile, found that only 25% of women thought it was “completely” or “somewhat” acceptable for celebrities to wear garments that displayed their nipples (compared to 45% of men).

In her 1975 seminal work Visual Pleasure and the Narrative Cinema, feminist film theorist Laura Mulvey unpacks the notion of the male gaze, where women are often presented in film as objects of male desire.

The continued disapproval of the visible nipple may suggest, she argues, that it is still considered as a sign of sexual objectification through the male gaze, rather than a personal choice that represents women’s confidence, empowerment and body positivity.

The nipple in fashion history

Fashion’s fascination with exposed breasts has a long and compelling history. During French queen Marie Antionette’s (1755-1793) reign, modest dress was confined to those of the lower classes. At the Court of Versailles, the décolleté (plunging neckline) was the height of fashion for women, and a mark of social standing.

Painting of Marie Antoinette with a rose
Marie Antoinette à la Rose by Élisabeth-Louise Vigée Le Brun (1783).
Wiki Commons

Marie Antoinette, a great advocate of style, was known to have a penchant for revealing fashion, and she was not alone. Émilie du Châtelet (1706-1749), a philosopher, mathematician and Voltaire’s mistress, was known for plunging necklines and exposed nipples which she would rouge to accentuate their appearance. Pauline Bonaparte, Napoleon’s sister, often did the same.

The fashion for breasts at the French Court could perhaps be traced as far back as the mistress of Charles VII (1403-1461), Agnès Sorel, who would purportedly leave her bodice unlaced and her breasts exposed.

Fast forward to the 20th century and countless celebrities from Marilyn Monroe to Jane Birkin have worn sheer clothing that displayed their breasts and nipples. Monroe famously wore a sheer dress when she sang Happy Birthday to US President John F. Kennedy in 1962. The dress from an original sketch by US designer Bob Mackie was so tight that Monroe was reportedly sewn into it, and chose to wear nothing underneath.

There are few better showcases for the fashion of the 2000s than Sex and the City (1998-2004). Set in New York City, it followed the lives of four women as they negotiated work, life, friendship and love, all while wearing the most fabulous clothes. Across episodes the series had a profound impact on fashion, launching designers and creating trends.

Samantha Jones’s faux nipples in Sex and the City.

In an episode aired in 2001, one of the female protagonists, Samantha Jones (played by Kim Cattrall), wore a pair of fake stick-on nipples under a blue vest top, for a date. Proclaiming them all the rage to her friends with the line, “nipples are huge right now”, she found herself a man, and quickly removed them and flung them across the room when he wasn’t looking.

For Jones, visible nipples were clearly an example of sexualisation as empowerment. Perhaps this moment was a precursor to Kim Kardashian’s lingerie label SKIMS releasing a nipple bra. In stark contrast, other Sex and the City cast members have revealed that they were afraid to show their real nipples on the show in case they were shunned by the film world.

From shock, to disapproval and on occasion admiration, debates about the appropriateness of visible nipples for women drone on. I for one respect celebrities like Sweeney for making a stand against societal expectations over the presentation of women’s bodies.

Freedom of self-expression is after all a manifestation of empowerment and bodily confidence. Long live the freed nipple.

Looking for something good? Cut through the noise with a carefully curated selection of the latest releases, live events and exhibitions, straight to your inbox every fortnight, on Fridays. Sign up here.

The Conversation

Naomi Braithwaite 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. A brief history of the exposed nipple in fashion – from Marie Antoinette to Sydney Sweeney – https://theconversation.com/a-brief-history-of-the-exposed-nipple-in-fashion-from-marie-antoinette-to-sydney-sweeney-269444

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Encouraging young people to vote requires understanding why they don’t

Source: The Conversation – Canada – By Christopher Alcantara, Professor of Political Science, Western University

Around the world, political institutions are under threat and democracy hangs in the balance. Deepening political divisions, political apathy and the rise of opportunistic populist leaders have all contributed to widespread democratic backsliding and a rise in authoritarianism.

Meeting this challenge requires active and engaged citizens. In Canada, there’s a strong sense that civic engagement is on the decline, especially among young people. Recent research commissioned by the Max Bell Foundation — a charity that works to improve educational, health and environmental outcomes for Canadians — suggests that the real story may be more complex.

Our research on political engagement has found that while today’s young Canadians are participating less in conventional political activities, they are increasingly active in other less traditional ways. How do we encourage youth to engage in all forms of civic life?

Ballots versus boycotts

Our analyses of Elections Canada voting data and survey data, collected through the Canada Election Study and Democracy Checkup projects, clearly illustrate that young people differ from older Canadians in how they participate in civic and political life.

Canadians between the ages of 18 and 34 are less likely to vote than those in other age cohorts and had the steepest decline in turnout from 2015 to 2021, when fewer than half of eligible young Canadians voted.

Young people are generally less knowledgeable and politically informed than older adults.

A graph shows voter turnout numbers in recent Canadian federal elections by age
Voter turnout numbers in recent Canadian federal elections by age.
(Elections Canada)

At the same time, young Canadians are at the forefront of discussing politics online, following politicians on social media and mobilizing their peers through digital platforms. They are more likely to take part in protests, petitions and political consumerism — from boycotts to buycotts — and to volunteer with community organizations and political campaigns at higher rates than other age groups.

a graph shows levels of political participation by age
Data on levels of political participation by age.
(Democracy Checkup surveys)

The real story isn’t that youth don’t care or aren’t political. It’s that they are turning away from conventional, formal participation in favour of alternative ways of sharing and expressing their views.

Explaining changing participation norms

Our analysis suggests that younger Canadians differ from their older counterparts across key factors that shape whether and how they participate.

Many young Canadians cite a lack of time as a barrier to engagement, have lower levels of political knowledge, report slightly lower levels of interest in politics and struggle to make the connection between politics and the issues they care about.

Our work also suggests that youth are noticeably less likely to see civic participation like voting as a duty, and they’re much more likely to be influenced by whether they believe their participation will make a difference.

This presents a particular challenge, because youth also tend to express higher levels of skepticism that their participation matters.

One final surprising finding is that more attention may need to be paid to understanding how political polarization affects youth. Young people may be increasingly put off from politics by hostility and conflict that they want to avoid.

Civic engagement beyond election day

Youth don’t seem to be tuning out but are instead finding different ways to engage. Nonetheless, declining interest in political engagement through formal institutions represents a real concern for democracy in Canada.

So how to build upon the areas where youth are already engaging, and bring young people back into conventional forms of civic engagement like voting?

Our conversations with civil society organizations suggest that civic engagement starts with effective civic education programs in schools, while highlighting the challenges these programs face — from educator training to curriculum design and sustainability over time.

They also highlight the challenge of reaching older youth, especially those referred to as NEET by statisticians — not in employment, education or training. Our interviewees shared their own successful strategies and emphasized the importance of reaching out to youth where they are and through the media and platforms that they prefer.

What comes next?

Democracies around the world are under pressure, and Canada is no exception. In this moment, it’s more critical than ever to pay attention to youth civic engagement.

Investing in civic education and encouraging civic participation early in life helps ensure young people have a voice in politics. But perhaps more importantly, it can also demonstrate how civic engagement can lead to change and challenge the feelings of powerlessness that drive disengagement. Youth participation helps build habits that last a lifetime and is essential to sustaining democracy for generations to come.

The future of Canadian democracy is in the hands of our youth. They must be equipped with the knowledge and the skills to shape it for the better.

The Conversation

Christopher Alcantara receives funding from Max Bell Foundation for this research report.

Craig Mutter receives funding from Max Bell Foundation for this research.

Laura Stephenson receives funding from Max Bell Foundation for this research.

– ref. Encouraging young people to vote requires understanding why they don’t – https://theconversation.com/encouraging-young-people-to-vote-requires-understanding-why-they-dont-270015

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Online harassment is silencing Canada’s health experts — institutions need to do more to protect them

Source: The Conversation – Canada – By Heidi J. S. Tworek, Professor of History and Public Policy, University of British Columbia

Canada has lost the measles elimination status it has held since 1998. To regain that status, one crucial factor is hearing from researchers who speak about vaccine safety in public.

Canada can’t afford to lose expert voices at a moment when the threat of vaccine-preventable diseases is rising. Yet our work suggests that online harassment is a growing deterrent that is driving researchers and scientists out of the conversations needed at this time.

Harassment is a long-standing problem in academia. While it occurs within different institutions and disciplines, it has increasingly taken the form of online attacks from people outside of academia. It’s a phenomenon that accelerated during the COVID-19 pandemic, and one where health experts are left to cope alone.

Canadian institutions and research organizations need to create broad support for these individuals.

The harms of online harassment

Our recent study on prominent Canadian health communicators — including university researchers and public health officials — found that 94 per cent, or 33 of 35 interviewees, had faced online abuse during the COVID-19 pandemic.

Online harassment goes beyond vaccines and COVID-19; climate change, gender diversity, immigration and other topics have all triggered a backlash. But we found that vaccination was one of the topics most likely to trigger abuse, and it’s an issue that has become increasingly politicized in Canada.

As with many issues in Canada, developments in the United States have played a major role. For instance, a 2021 study on vaccine hesitancy in Canada showed how social media conversations on vaccinations were heavily influenced by discussions in the U.S. It turned out that Canadians followed a median of 32 Canadian accounts and 87 American accounts.

With such interconnected information ecosystems, anti-science harassment directed at American researchers routinely spills into Canadian online spaces. This is worsened when senior officials in the U.S. administration publicly express a lack of support for immunization and evidence-based health recommendations.

Canadian universities and academic institutions need to develop mitigation and support strategies to deal with online harassment fuelled by these realities.

We can learn from action plans by U.S.-based universities and coalitions. Canada can also learn from models in countries like the Netherlands that have created national initiatives to support researchers experiencing harassment.

Hostility that threatens public health

While academics should be comfortable having their ideas challenged, technology-facilitated harassment is very different. Online harassment is often linked with other forms of targeted abuse and includes acts of doxxing, reputation attacks or threatening and sexualized messaging, among others.

Though this hostility often targets individuals working on politically contested issues, researchers from equity-deserving groups face online abuse that builds on systemic inequities related to race, gender, sexuality and other identity factors.

Online abuse can harm mental health, provoke fears about employment or grants and undermine academic freedom, as the Canadian Association of University Teachers observes. Our research found that health communicators faced the “psychological toll” of reading hostile emails day after day, with several reporting fear, sadness or anxiety in response to threats of violence.

A racialized expert recounted how personal attacks on her appearance and background “take a toll,” while a health journalist said that messages like one wishing her “blood clots” sometimes kept her awake at night. Several interviewees described exhaustion, worry and depressive symptoms, highlighting the hidden burden of online harassment.

Besides having serious personal, institutional and societal consequences, this reality risks creating information gaps that could be quickly filled by conspiracy theories. Some health researchers decided to stop media interviews or social media posts on controversial issues. So should they simply avoid public engagement on contentious topics?

While this approach might lessen the risks, it would also dramatically reduce the impact of their expertise. Public engagement is not only a key part of research grants but it also ensures that Canadians benefit directly from research.

Currently, scholars and public health communicators targeted with online abuse mainly use individual coping strategies such as deleting social media accounts, withdrawing from public communication or accepting abuse as inevitable.

These strategies, however, leave individuals to address attacks in isolation. While such measures provide temporary relief, they reinforce self-censorship and hamper public access to expert knowledge.

The need for ‘wraparound’ support

Institutions need to adopt “wraparound” support. This approach acknowledges researcher agency and institutional responsibility through a rights-based framework. It also shifts responsibility from individuals to institutions.

Unlike many universities’ current siloed and inflexible approach, a wraparound approach co-ordinates and integrates multiple domains of support.

For instance, some targeted individuals may not face legal or safety risks but can benefit from psychological support. Others may need assistance with cybersecurity risks or removing online mentions of personal information like their home address or children’s school.

Our institution, the University of British Columbia, for example, offers cybersecurity assistance, mental health support and other key elements of a response.

However, when we consulted faculty and staff, we learned that people found it daunting to figure out all the supports available and how to access them. We created an online resource to help. York University solved that problem by creating a map.

Canadian universities can also turn to international models for inspiration. Fourteen universities in the Netherlands, for instance, participate in a joint SafeScience initiative, which offers guidance and a national helpline to report incidents. Germany’s SciComm-Support provides resources, training and free counselling to researchers.

If we expect scientists and health experts to speak out about issues like measles vaccination for the good of society, they must know that their employers and institutions will stand with them, that they will have their backs.

Canada cannot prepare for future public health emergencies, like another pandemic, without protecting the safety of researchers and their freedom to pursue their lines of inquiry without fear.

Immunity and Society is a new series from The Conversation Canada that presents new vaccine discoveries and immune-based innovations that are changing how we understand and protect human health. Through a partnership with the Bridge Research Consortium, these articles — written by academics in Canada at the forefront of immunology and biomanufacturing — explore the latest developments and their social impacts.

The Conversation

Heidi J. S. Tworek receives funding from the Bridge Research Consortium (BRC), part of Canada’s Immuno-Engineering and Biomanufacturing Hub, which in turn is funded by the Canada Biomedical Research Fund, Canada Foundation for Innovation and the BC Knowledge Development Fund. She also receives funding from the Canada Research Chair Programme and the Social Sciences and Humanities Research Council.

Chris Tenove receives funding from the Bridge Research Consortium (BRC), part of Canada’s Immuno-Engineering and
Biomanufacturing Hub, which in turn is funded by the Canada Biomedical Research Fund, Canada Foundation for Innovation and the BC Knowledge Development Fund.

Netheena Neena Mathews receives funding from the Bridge Research Consortium (BRC), part of Canada’s Immuno-Engineering and Biomanufacturing Hub, which in turn is funded by the Canada Biomedical Research Fund, Canada Foundation for Innovation and the BC Knowledge Development Fund.

– ref. Online harassment is silencing Canada’s health experts — institutions need to do more to protect them – https://theconversation.com/online-harassment-is-silencing-canadas-health-experts-institutions-need-to-do-more-to-protect-them-267532

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An important wetland in Ghana is under siege. Researchers investigate the real issues

Source: The Conversation – Africa – By Stephen Leonard Mensah, PhD Candidate, University of Memphis

Wetlands are vital ecological resources that provide several benefits in urban and peri-urban areas. They slow down flood waters, and act as a source of fishing and farming livelihoods. They also provide socio-cultural benefits for local communities. But some of these valuable ecosystems, due to their presence in prime locations, are at the centre of competing cultural, ecological and economic interests. Property development, especially, is a threat to wetlands.

The 2025 Global Wetland Outlook emphasises that the protection of wetlands is key to sustainable development. However, since 1970, about 411 million hectares of wetlands have been lost. In Africa, degradation is widespread and many are in poor condition.

We are a multidisciplinary team of researchers working in the area of resilience, sustainability and justice in urban transitions.

Our research highlights some of the local-level issues and conflicting interests that are shaping the rapid destruction of the Sakumono Ramsar Site in Tema, Ghana. Under the Ramsar Convention, a Ramsar site is a designated wetland with special natural significance.

We found institutional complicity and the lack of engagement with communities to be key drivers shaping current wetland conditions. Our study proposes a model for enforcing regulations and asserting the community’s right to nature for socio-cultural purposes.



Read more:
A root cause of flooding in Accra: developers clogging up the city’s wetlands

Tema: wetlands in an industrial city

Tema was developed from a small fishing community into an industrialised port city by independent Ghana’s first president, Kwame Nkrumah. Its purpose was to facilitate international trade and vibrant economic development. It is one of Ghana’s most important cities and has been experiencing urban expansion and land use changes. This has led to encroachment in environmentally sensitive areas, including the Ramsar site.

The Sakumono wetland was officially designated a Ramsar site in 1992 to protect its rich biodiversity. It covers about 1,400 hectares and is protected by several regulations, including the Wetland Management Regulations Act, 1999.

But the site has, over the years, witnessed rapid depletion and intense encroachment from property development. Approximately 80% of the Sakumono Ramsar Site has been encroached on, leaving only about 20% of the wetland intact.

Population in the wetland’s catchment area had grown from about 114,600 in 1984 to over 500,000 by 2000, indicating that large numbers of people live around and rely on the wetland. Although the exact number of people currently affected by the wetlands encroachment is unknown, the dense surrounding population suggests that many households, especially those engaged in farming and fishing, have likely experienced reduced access and livelihood displacement. Like other wetlands in Ghana, the Sakumomo Ramsar site risks eventual destruction if nothing is done to reverse current trends.

The president of Ghana has called for heavy punishment for individuals who encroach on Ramsar sites. Both community and institutional respondents in our research claimed, however, that it was the political elites who were behind unbridled property development in the first place.



Read more:
Flooding incidents in Ghana’s capital are on the rise. Researchers chase the cause

Multiple and conflicting interests in wetlands management

The main objective of our study was to analyse stakeholders’ perspectives on the use, value and management of wetlands. We evaluated the impact of these views on the sustainable management of ecologically sensitive areas. We conducted in-depth interviews with community residents, community leaders and opinion leaders. We also interviewed officials from metropolitan and municipal assemblies. The research was conducted in the Sakumono community, where the Sakumono Ramsar site is located.

Conflicting views on wetlands value: while the value of the site lies in its economic and ecological benefits, community residents were more interested in its economic value. That is, how it provides livelihood opportunities through farming and fishing activities.

Residents wondered why developers were allowed to exploit portions of the wetlands for building purposes, while they were prevented from fishing and farming. One of the residents said:

See rich and influential people buying land in the wetland area and using it for building properties. But we are not permitted to fish there.

For state institutions, protecting the wetland meant restricting access for community members. They encouraged activities such as tree planting and periodic desilting.

Conflicting views on wetlands use: the views of stakeholders also showed the changing understanding of the use of wetlands. An official from the forestry commission revealed that the wetland was acquired by the state during the 1980s for conservation. But other institutional officials, such as those of the lands commission, revealed that it had become a prime area for property development. Powerful developers bypass the land registration process and build without a permit.

The size of the Ramsar site has reduced because people are acquiring the wetland, including the buffer area, for residential development. Even though the wetland area is demarcated as a protected area, many of the politically connected developers go behind us and build without a permit.

Conflicting views on wetlands management: our research revealed contradictions between state institutions and community stakeholders. For instance, traditional authorities were of the view that:

Since the management of the wetland is not under our control, we are not responsible for the current developments taking place in and around the demarcated area.

The traditional authorities said they were not consulted and did not benefit from the wetland. This perhaps explains why they watched on as destruction continued. A member of the traditional council said:

As leaders of the community, we are not consulted about how the wetland is managed. You always hear the forestry commission accusing community leaders that we are selling the land. We can’t sell land that does not belong to us.

Towards a community-based stewardship model

Communities should be at the centre of wetlands management. We propose a stewardship-based co-management model that enforces environmental and conservation regulations. It emphasises working with a range of stakeholders. This includes government agencies, traditional authorities and environmentally conscious community members. We call for an updated wetlands management plan that reflects recent changes, but that is also fair, responsible and protective for present and future generations. This is essential for building sustainable communities in Ghana and beyond.

The Conversation

Louis Kusi Frimpong receives funding from African Peacebuilding and Developmental Dynamics (APDD) through the Individual Research Fellowship (IRF).

Seth Asare Okyere and Stephen Leonard Mensah do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.

– ref. An important wetland in Ghana is under siege. Researchers investigate the real issues – https://theconversation.com/an-important-wetland-in-ghana-is-under-siege-researchers-investigate-the-real-issues-269016

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How does Narcan work? Mapping how it reverses opioid overdose can provide a molecular blueprint for more effective drugs

Source: The Conversation – USA – By Saif Khan, Ph.D. Candidate in Biology, University of Southern California

Naloxone competes with opioids for the same receptor on the surface of neurons. Matt Rourke/AP Photo

Naloxone, also known by the brand name Narcan, is one of the most important drugs in the United States’ fight against the opioid crisis. It reverses an opioid overdose nearly instantly, restarting breathing in a person who was unresponsive moments before and on the brink of death. To bystanders witnessing it being administered, naloxone can appear almost supernatural.

Although the Food and Drug Administration approved naloxone for medical use in 1971 and for over-the-counter purchase in 2023, exactly how it works is still unclear. Researchers know naloxone acts on opioid receptors, a family of proteins responsible for the body’s response to pain. When opioids such as morphine and fentanyl bind to these receptors, they produce not only pain relief and euphoria but also dangerous side effects. Naloxone competes with opioids for access to these receptors, preventing the drugs from triggering effects in the body. How it does this at the molecular level, however, has been an ongoing question.

In our recently published research in the journal Nature, my team and I were able to provide some definitive evidence of how naloxone works by capturing images of it in action for the first time.

Knowing how to use naloxone can save lives.

Biology of opioids

To better grasp how naloxone works, it’s helpful to first zoom in on the biology behind opioids.

One member of the family of opioid receptors, MOR – short for µ-opioid receptor – is a central player in regulating the body’s response to pain. It sits on the surface of neurons, mostly in the brain and spinal cord, and acts as a communication hub.

When an opioid – such as an endorphin, the body’s natural painkillers – interacts with MOR, it changes the structure of the receptor. This change in shape allows what’s called a G protein to bind to the receptor and trigger a signal to the rest of the body to reduce pain, induce pleasure, or – in the case of overdose – dangerously slow breathing and heart rate.

Diagram of different configurations of MOR
When a molecule binds to the µ-opioid receptor, it changes its structure and elicits an effect. Antagonists like naloxone inactivate the µ-opioid receptor, while agonists like fentanyl activate it.
Bensaccount/Wikimedia Commons

In everyday terms, MOR is like a lock on the outside of the cell. The G protein is the mechanism inside the lock that turns when the correct key – in this case, an endorphin or a drug like fentanyl – goes in. For decades, scientists believed that an opioid’s ability to enable this signaling cascade was linked to how effectively it reshaped the structure of the receptor – essentially, whether the lock could open wide enough for the internal mechanism of the G-protein to engage.

Yet, recent research – including our work – has revealed that the critical step to how opioids work is not how wide they open the lock but how well the mechanism works. G proteins act like a switch, releasing one molecule in exchange for another molecule that triggers the protein to send the signal that sets off opioid effects.

In essence, drugs like fentanyl, by acting on the receptor, transmit physical changes to G proteins that result in the switch flipping more rapidly. What we now see is that naloxone jams the mechanism, preventing the switch from flipping and sending the signal.

Capturing the switch

Researchers know that the effects of opioids are triggered when the G protein switch is flipped. But what does this process look like?

For years, attempts to visualize this mechanism were largely limited to two states – before the G protein binds to the µ-opioid receptor, and after the molecule was released from the G protein. The states in between were considered too unstable to isolate. My team and I wanted to capture these unseen states moment by moment as the switch flips and the molecule is released.

To do this, we used a technique called cryo-electron microscopy, which freezes molecules in motion to visualize them at near-atomic resolution. For both naloxone and the opioid drug loperamide (Imodium), we trapped the G protein bound to the opioid receptor right before it released the molecule.

We captured four distinct structural states leading up to the release of the molecule from the G protein.

The first of these, which we call the latent state, is the earliest form of the opioid receptor and G protein after they make contact. We found that both the opioid receptor and the G protein are inactive at this point. Moreover, naloxone stabilizes this latent state. What this means is that naloxone effectively jams the mechanism right at the start, preventing all subsequent steps required for activation.

Diagram of MOR and G protein in six different states of activation
How the µ-opioid receptor (top half of the structure) and G protein (bottom half of the structure) are configured is key to the effects of naloxone and opioids.
Saif Khan et al/Nature, CC BY-NC-ND

In the absence of naloxone, an opioid drug promotes a transition to the remaining three states: The G-protein rotates and aligns itself with the receptor (engaged), swings open the door blocking the molecule that would trigger the switch from flipping (unlatched), and holds that door open so the molecule can be released (primed) and send the signal to carry out the drug’s effects.

To confirm that our snapshots reflect what’s really happening, we performed extensive computational simulations to watch these four states change over time. Together, these findings point to the molecular root of naloxone’s therapeutic effects: By stalling the opioid receptor and G protein at a latent state, it shuts down opioid signaling, reversing an opioid overdose within minutes.

Visualizing new drugs

Designing a new key for a lock is most successfully done when you know exactly what that lock looks like. By mapping the exact sequence of how opioids interact with opioid receptors and pinpointing where different drugs can intervene in this process, our findings provide a blueprint for engineering the next generation of opioid medicines and overdose antidotes.

For example, one of the persistent challenges with naloxone is that it must often be administered repeatedly during an overdose. This is especially the case for fentanyl overdoses, where the opioid can outcompete or outlast the effects of the treatment.

Knowing that naloxone works by stalling the µ-opioid receptor in an early, latent state suggests that molecules that can bind more tightly or more selectively to this form of the receptor could be more effective at stabilizing this inactive state and thus preventing an opioid’s effects.

By uncovering the structure of molecules involved in opioid signaling, researchers may be able to develop drugs that provide longer-lasting protection against overdose.

The Conversation

This research was supported by the National Institutes of Health.

– ref. How does Narcan work? Mapping how it reverses opioid overdose can provide a molecular blueprint for more effective drugs – https://theconversation.com/how-does-narcan-work-mapping-how-it-reverses-opioid-overdose-can-provide-a-molecular-blueprint-for-more-effective-drugs-269706

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Absence of evidence is not evidence of absence – and that affects what scientific journals choose to publish

Source: The Conversation – USA – By Mark Louie Ramos, Assistant Research Professor of Health Policy and Administration, Penn State

Careful planning and analysis are part of trying to reduce the chance of a false-positive finding. Arnon Mungyodklang/iStock via Getty Images Plus

Should you believe the findings of scientific studies? Amid current concerns about the public’s trust in science, old arguments are resurfacing that can sow confusion.

As a statistician involved in research for many years, I know the care that goes into designing a good study capable of coming up with meaningful results. Understanding what the results of a particular study are and are not saying can help you sift through what you see in the news or on social media.

Let me walk you through the scientific process, from investigation to publication. The research results you hear about crucially depend on the way scientists formulate the questions they’re investigating.

The scientific method and the null hypothesis

Researchers in all kinds of fields use the scientific method to investigate the questions they’re interested in.

First, a scientist formulates a new claim – what’s called a hypothesis. For example, is having some genetic mutations in BRCA genes related to a higher risk of breast cancer? Then they gather data relevant to the hypothesis and decide, based on the data, whether that initial claim was correct or not.

It’s intuitive to think that this decision is cleanly dichotomous – that the researcher decides the hypothesis is either true or false. But of course, just because you decide something doesn’t mean you’re right.

If the claim is really false but the researcher decides, based on the evidence, it’s true – a false positive – they commit what’s called a Type 1 error. If the claim is really true but the researcher fails to see that – a false-negative conclusion – then they commit a Type 2 error.

Moreover, in the real world, it gets a little messier. It’s really hard to decide about the truth or falsity of a claim just based on what’s observed.

For that reason, most scientists employ what is called the null hypothesis significance testing framework. Here’s how it works: A researcher first states a “null hypothesis,” something that’s contrary to what they want to prove. For instance, in our example the null hypothesis is that BRCA genetic mutations are not associated with increased breast cancer occurrence.

The scientist still gathers data and makes a decision, but the decision is not about whether the null is true. Instead, a researcher decides whether there’s enough evidence to reject the null hypothesis or not.

man in white coat in lab looking at tablet
Careful statistical analysis along with a well-formulated null hypothesis lend confidence to a study finding.
Jackyenjoyphotography/Moment via Getty Images

What rejecting the null does and doesn’t mean

Understanding this distinction is crucial. Rejecting the null is equivalent in practice to acting as though it is false – in the example, rejecting the null means claiming that those with some BRCA gene mutations do have a higher risk of breast cancer. Along with other evidence, such as the size of the increased risk, this outcome can justify recommending early breast cancer screening for people with the identified BRCA mutations.

But failing to reject the null hypothesis doesn’t imply that it’s true – in this case, it doesn’t mean there is no association between the BRCA mutations and breast cancer. Rather, such a result is inconclusive; there’s not enough evidence to claim there is an association. A negative result – inadequate evidence to say the null is false – does not necessarily invite the researcher to believe the null is true.

This is because null hypothesis significance testing is set up to control for Type 1 error (false positive) at a level defined in advance by the researcher but at the cost of having less control over Type 2 error (false negative).

A researcher’s chances of correctly rejecting the null if there is increased risk can depend on how much data they have, how complex the design of the study is and, most importantly, how large the effect actually is. It’s much easier to reject the null if BRCA mutations truly increase cancer risk many times than it is if the risk is only slightly elevated. A researcher can end up with a result that is not statistically significant but cannot rule out the possibility of an increased risk that is too small for the study to detect.

Which results are more often publicized

Once they have their result and the researchers want to disseminate their work, they typically do so through peer-reviewed publication. Journal publishers consider a researcher’s write-up of their study, send it out for other scientists to review, and then decide whether to publish it.

In this process, the publishers tend to favor studies that rejected their null hypothesis over those that failed to reject it. This is called positive publication bias.

It is natural for publishers to prefer studies that support new claims since they objectively carry more information than studies that failed to reject their null hypothesis. Journals want to publish something new and noteworthy.

Many sources flag this phenomenon as “bad science,” but is it really? Remember, the framework used to make decisions about scientific claims is intentionally only capable of either rejecting the null hypothesis – in other words, supporting the claim – or alternatively declaring inconclusive results.

The framework isn’t designed to be able to prove the null hypothesis. That said, researchers can reverse the design of a scientific investigation so that a previous claim becomes the null hypothesis in a new study with fresh data.

For instance, rather than a null hypothesis that there is no association between BRCA mutations and breast cancer, the null hypothesis becomes that the increased breast cancer risk from BRCA mutations is equal to or greater than some value the researcher settles on before gathering fresh data.

Rejecting the null this time would mean the increased risk is smaller than that set value, thus supporting the claim consistent with what had previously been the null hypothesis on prior data. In the example, rejecting the null means the effect of BRCA genes is small enough to be practically negligible in terms of developing breast cancer.

It’s critical for a researcher to structure their study so that what they’re interested in proving is aligned with the rejection of the null. Publishers are naturally less inclined to consider studies that failed to reject their null hypothesis, not because they do not want to publish studies that support negative statements but because null hypothesis significance testing does not actually support negative statements. Failure to reject the null just means your results are inconclusive – and may perhaps seem less newsworthy.

library shelves with research journals
Research journals want to publish results that will have an impact.
luoman/iStock via Getty Images Plus

What positive publication bias does

So what does the practice of preferring to publish studies that reject their null hypothesis do?

While we can’t know for certain, we can see how this plays out under different circumstances. You can explore the scenarios in this app I made.

If scientists are acting in good faith, using null hypothesis significance testing appropriately, it turns out that positive publication bias on the part of scientific journal publishers will increase the proportion of true discoveries in their pages much more than it will increase the proportion of false positives.

If editors did not exercise any positive publication bias, journals would be almost entirely full of studies with inconclusive results.

Of course, if scientists are not acting in good faith and are just interested in getting published while ignoring proper use of statistical tests, that can lead to false-positive rates being as high or higher than the rate of true discoveries. But this possibility is true even without positive publication bias.

The Conversation

Mark Louie Ramos 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. Absence of evidence is not evidence of absence – and that affects what scientific journals choose to publish – https://theconversation.com/absence-of-evidence-is-not-evidence-of-absence-and-that-affects-what-scientific-journals-choose-to-publish-264854

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L’Univers a-t-il un début ? Le Big Bang contre la théorie de l’état stationnaire

Source: The Conversation – France in French (2) – By Waleed Mouhali, Enseignant-chercheur en Physique, ECE Paris

La question de l’évolution de l’Univers a attisé de nombreux débats au cours de l’histoire de la physique. Au début du XXe siècle, deux camps de scientifiques s’affrontèrent : d’un côté, les tenants d’un Univers stable et ayant toujours existé, de l’autre, les physiciens qui adhèrent au modèle d’un atome primitif, ancêtre de notre théorie du Big Bang.

Au cours du XXe siècle, la cosmologie a été bouleversée par deux visions concurrentes du Cosmos. D’un côté, Georges Lemaître proposait l’hypothèse d’un « atome primitif », précurseur du Big Bang, selon laquelle l’Univers a une histoire et un commencement. De l’autre, Fred Hoyle, Thomas Gold et Hermann Bondi défendaient en 1948 une alternative : l’état stationnaire, un modèle où l’Univers, en expansion, reste inchangé à grande échelle grâce à une création continue de matière.

Cette théorie séduisait par son élégance : elle évitait l’idée d’un début absolu et renouait avec de vieilles intuitions philosophiques – puisqu’elles remontent à la Grèce antique – selon lesquelles le Cosmos était éternel et immuable. Mais elle allait bientôt se heurter à l’épreuve des observations. Le déclin de cette théorie fascinante s’inscrit dans une querelle scientifique majeure, au terme de laquelle le modèle de l’atome primitif de Georges Lemaître s’est imposé.

Le modèle de l’état stationnaire : un Univers éternel et immuable

En 1948, Fred Hoyle, Thomas Gold et Hermann Bondi introduisent le modèle cosmologique de l’état stationnaire. Leur approche repose sur deux principes fondamentaux. D’une part, le principe cosmologique parfait : non seulement l’Univers est homogène et isotrope dans l’espace – cela signifie qu’à grande échelle, l’Univers présente les mêmes propriétés en tout point et dans toutes les directions d’observation, aucun lieu ni direction n’est privilégiés – mais il l’est aussi dans le temps – ses propriétés sont globalement les mêmes à toutes les époques. D’autre part, ils postulent la création continue de matière pour compenser l’expansion observée de l’Univers mise en évidence par Hubble, de la matière est continuellement créée à un rythme très faible (de l’ordre d’un atome d’hydrogène par mètre cube tous les milliards d’années).

Ce modèle évite un commencement à l’Univers, et par conséquent la question philosophique et scientifique de la création de quelque chose à partir du néant. Il offre un cadre élégant, statique à grande échelle, dans lequel l’Univers n’a ni origine ni fin. D’un point de vue philosophique, il s’inscrit dans la continuité d’une vision éternelle du Cosmos, une position qui était majoritaire parmi les savants de l’Antiquité jusqu’au XVIIIe siècle, une idée déjà défendue par les stoïciens ou Aristote. À noter qu’Aristote s’interroge sur les limites de l’Univers et rejette l’idée d’un Univers infini, qu’il juge physiquement insoutenable.

Pourquoi le modèle de l’état stationnaire a-t-il séduit ?

Le modèle de l’état stationnaire a longtemps bénéficié d’un certain prestige pour plusieurs raisons. D’abord, sa simplicité philosophique, que l’on vient de décrire, mais aussi sa stabilité mathématique, puisqu’il repose sur des solutions simples des équations cosmologiques formulées par Einstein dans le cadre de sa relativité générale. Enfin, il séduit aussi du fait de son esthétique scientifique : un Univers inchangé dans le temps apparaît comme harmonieux et prévisible.

Le modèle de l’état stationnaire avait donc tout pour plaire. Sûr de sa théorie, c’est Fred Hoyle, en voulant se moquer et tourner en dérision le modèle concurrent de l’atome primitif qu’il considérait comme absurde, qui forge le terme de Big Bang lors d’une émission de radio sur la BBC en 1949. Et pourtant…

Le modèle de l’atome primitif de Lemaître : un précurseur du Big Bang

Avant même la formulation du Big Bang moderne tel que nous le concevons aujourd’hui, le prêtre et physicien belge Georges Lemaître avait développé en 1931 une hypothèse audacieuse : le modèle de l’atome primitif. Selon lui, l’Univers aurait été créé à partir de la désintégration d’un « atome cosmique », un point originel dense et chaud, à l’origine de l’expansion de l’espace. Il complète ainsi un modèle qu’il avait commencé à formuler dès 1927, dans lequel il proposait déjà un Univers en expansion.

Photo d’époque en noir et blanc des trois scientifiques
George Lemaître, au centre, en compagnie d’Albert Einstein, à droite, et de Robert Andrews Millikan à gauche.
Wikimedia

Lemaître s’appuie sur les solutions dynamiques des équations d’Einstein et sur les observations de Edwin Hubble, astronome américain ayant découvert que les galaxies s’éloignent des unes des autres. Il conçoit un Univers en expansion, mais doté d’un passé à la fois physique et avec un commencement. Lemaître imaginait l’atome primitif comme un noyau contenant toute la matière de l’Univers dont la fission aurait déclenché l’expansion cosmique. Il interprétait les rayons cosmiques, récemment découverts, comme des résidus de cette désintégration initiale. Cette hypothèse s’est avérée inexacte puisqu’ils proviennent en réalité de phénomènes astrophysiques situés dans notre environnement cosmique proche.

Contrairement à Hoyle, il accepte la notion de début sans lien avec une quelconque création religieuse, qu’il considère en tant qu’ecclésiaste comme une notion philosophique et non pas comme un événement particulier. Le modèle de l’atome primitif est le précurseur direct de ce que l’on appellera par découvertes successives le modèle du Big Bang, qui s’imposera plus tard, notamment grâce à ses prédictions observables.

Les preuves observationnelles contre l’état stationnaire

Malgré son attrait initial, le modèle de l’état stationnaire a commencé à vaciller face à des données de plus en plus précises. Le coup le plus dur arrive en 1964, quand Arno Penzias et Robert Wilson détectent par hasard un signal radio bruité provenant de toutes les directions d’observation. Ce bruit, appelé rayonnement cosmologique, est en fait la lueur fossile laissée par l’Univers très jeune, exactement comme l’avaient prédit les partisans du Big Bang. Le modèle stationnaire, lui, n’a aucun moyen d’expliquer un tel vestige. Le fond diffus cosmologique, découvert en 1965, est le témoin le plus direct du Big Bang. Ses détails ont ensuite été étudiés par les satellites COBE (1992), WMAP (2003) et Planck (2009).

Trois cartes du fond diffus cosmologiques au fil du temps, selon les premières mesures de Penzias et Wilson puis suite aux mesures des missions spatiales COBE et WMAP
Avec les missions spatiales successives, le fond diffus cosmologique a pu être mesuré de plus en plus précisément. Son existence-même est un argument en faveur du modèle du Big Bang.
NASA/Wikimedia

D’autres indices vont dans le même sens : les galaxies lointaines – dont l’image qui nous parvient d’elle date du moment où elles étaient encore jeunes – n’ont pas la même apparence que les galaxies actuelles. De plus, les quasars, sortes de noyaux galactiques hyperactifs, étaient bien plus nombreux dans le passé qu’aujourd’hui. Ces différences montrent que l’Univers évolue au fil du temps, contrairement à ce qu’affirmait l’état stationnaire.

Enfin, le Big Bang prédit avec une grande précision les proportions des éléments légers (hélium, deutérium, lithium) formés durant les toutes premières minutes. Les mesures des éléments fossiles qui sont parvenus jusqu’à nous confirment ces valeurs. Le modèle stationnaire, qui n’inclut pas de phase chaude et dense initiale, est incapable de les expliquer.

L’évolution de la cosmologie moderne

Face à ces observations, la communauté scientifique adopte progressivement le modèle du Big Bang comme modèle standard. Pourtant, Fred Hoyle, dans les années 1990, refusant d’abandonner son hypothèse, propose un modèle dit quasi stationnaire, mais il reste marginal.

Aujourd’hui, le modèle ΛCDM (Lambda Cold Dark Matter), une version étendue du Big Bang qui intègre la constante cosmologique, l’idée selon laquelle il existe une minuscule énergie du vide, identique partout, exerçant une pression qui accélère l’expansion de l’Univers, est considéré comme le cadre le plus complet pour décrire l’évolution de l’univers. Introduite par Einstein en 1917 pour contrecarrer l’effet de la gravité dans un Univers qu’il pensait lui-même statique, elle a été réhabilitée sous le nom d’énergie sombre pour expliquer l’accélération observée, est considéré comme le cadre le plus complet pour décrire l’évolution de l’Univers.

Le modèle de l’état stationnaire illustre un cas typique d’élégance théorique confrontée à la rigueur de l’expérimentation. Cette controverse a stimulé les débats, inspiré des développements mathématiques et permis une meilleure compréhension de ce qu’est une bonne théorie scientifique : cohérente, testable, et surtout, réfutable.

Elle rappelle aussi que la science avance non par dogme, mais par confrontation avec la réalité du cosmos. Et si certaines théories comme celle de la simulation ou du multivers flirtent aujourd’hui avec la frontière de ce que l’on est capable de tester, elles perpétuent une tradition millénaire : tenter de comprendre ce qui, depuis toujours, nous dépasse.

The Conversation

Waleed Mouhali 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. L’Univers a-t-il un début ? Le Big Bang contre la théorie de l’état stationnaire – https://theconversation.com/lunivers-a-t-il-un-debut-le-big-bang-contre-la-theorie-de-letat-stationnaire-269855

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Votre chien ou chat vieillit ? Des gestes simples pour prolonger sa qualité de vie

Source: The Conversation – France in French (2) – By Sara Hoummady, DMV, PhD, Associate professor in ethology and animal nutrition, UniLaSalle

En vieillissant, les besoin des animaux de compagnie évoluent. Ginger / The Conversation, CC BY-ND

Déjà, ses premiers poils gris. Votre chien ou votre chat a pris un petit coup de vieux. Comment prendre soin de lui à présent ? Des chercheurs se sont penchés sur la question et prodiguent quelques conseils aisés à mettre en œuvre.

En France, avec une espérance de vie moyenne de 11,3 ans chez les chiens comme chez les chats, la gériatrie animale est devenue indispensable. Les connaissances progressent rapidement pour mieux accompagner ces animaux. On sait désormais que quelques aménagements simples améliorent nettement le confort et la qualité de vie d’un chat ou d’un chien âgé. L’essentiel pour les propriétaires est de ne pas rester observateur passif du vieillissement de leur compagnon à quatre pattes.

À quel âge mon chien ou mon chat peut-il être considéré comme âgé ?

Une recherche portant sur plus de deux millions de chats et plus de quatre millions de chiens a permis de mieux définir leurs différents stades de vie. Chez le chat, l’entrée dans le “troisième âge” se situe autour de 10 ans. Le “troisième âge” comprend le stade mature, sénior et super-sénior.

Selon cette même étude, pour le chien, la situation est moins uniforme : la vitesse de vieillissement dépend fortement de la taille.

  • Les chiens de petit format (toy et small, des races dont le poids est inférieur à 9 kg, comme les chihuahas ou les cavalier king charles) entrent dans le troisième âge vers 7 ans, puis deviennent “séniors” autour de 12 ans.

  • Les chiens de format moyen à grand, de plus de 9 kg, comme les welsh corgis, les golden retrievers ou les bergers australiens par exemple, y accèdent plus tôt : environ 6 ans pour le début du troisième âge, puis 10 ans pour le stade sénior.

Golden retriever âgé allongé
Même super senior, ce golden retriever peut conserver une bonne qualité de vie.
Nhung Le/Unsplash, CC BY

Il est important d’être rassuré : passer dans ce nouveau stade ne signifie absolument pas que “la fin” approche. Cela indique surtout qu’il est temps d’être plus attentif à son compagnon et d’adapter progressivement son suivi, son environnement et ses soins pour l’aider à vieillir dans les meilleures conditions.

Qu’est-ce qu’un vieillissement sain ? Comment l’évaluer chez son animal ?

Avant de parler de “vieillissement sain”, il est utile de rappeler ce qu’est le vieillissement : un processus naturel, progressif et inévitable. Avec le temps, les animaux tolèrent moins bien les stress de leur environnement et leurs cellules accumulent des dommages, ce qui entraîne des modifications physiologiques variées.

Qu’entend-on alors par un chien ou un chat vieillissant “en bonne santé” ? Un récent article de consensus auquel j’ai participé propose une définition adaptée à nos animaux de compagnie : un animal âgé en bonne santé est celui qui conserve suffisamment de capacités et de résistance pour répondre à ses besoins physiques, comportementaux, sociaux et émotionnels, tout en maintenant une relation stable et positive avec son humain.

Certains signes sont tout à fait normaux : poils qui grisonnent, léger tartre, peau plus fine, perception sensorielle un peu diminuée mais sans impact notable sur la qualité de vie.

gros plan cocker
Quelques changements physiques sont tout à fait normaux.
Ava Tyler/Unsplash, CC BY

En revanche, des difficultés locomotrices entravant l’accès aux ressources (difficulté à se lever, à monter les escaliers ou à interagir facilement avec vous) ne doivent pas être considérées comme de simples manifestations de l’âge. Il en va de même avec les premiers signes de dysfonction cognitive (un syndrome qui présente quelques similitudes avec Alzheimer), lorsqu’un chien ou un chat a du mal à retrouver sa gamelle ou semble perdu dans la maison, par exemple. Ces cas nécessitent un avis vétérinaire.

La qualité de vie devient donc le critère central pour évaluer si un animal suit une trajectoire de vieillissement harmonieuse. Chez le chien et le chat, on utilise désormais la notion de fragilité, issue de la gériatrie humaine (voir tableau ci-dessous).

Comment évaluer la fragilité de son animal ?

Les animaux classés comme fragiles sont plus susceptibles de développer des maladies et doivent faire l’objet d’un suivi plus rapproché.

L’intérêt majeur de cette approche est que, comme chez l’humain, la fragilité repérée tôt pourrait parfois être atténuée. D’où l’importance d’un dépistage régulier et d’un accompagnement précoce pour soutenir au mieux nos compagnons âgés.

Quelques aménagements à mettre en place

La première étape consiste à rendre l’environnement de l’animal plus accessible afin qu’il puisse atteindre facilement toutes ses ressources : nourriture, eau, lieux de repos, espaces de cachette, zones d’interaction… De simples aménagements peuvent déjà faire une vraie différence : petits escaliers pour monter sur le canapé, chauffeuses ou coussins fermes et peu hauts, gamelles surélevées pour les chiens et chats souffrant d’arthrose.

Très beau chat roux sur un coussin rond
L’utilisation de coussins hauts ou chauffeuses permet au chat d’être en hauteur, avec un accès facilité.
Ginger/The Conversation, CC BY-ND

Multiplier les points d’accès est également utile : deux ou trois zones d’alimentation, plusieurs endroits pour dormir, et davantage de litières, faciles à enjamber. Certains bacs du commerce sont trop hauts pour des chats arthrosiques ; un plateau large à rebord bas peut être bien plus confortable.

Maintenir une relation apaisée et positive apparait essentiel. Un comportement jugé « indésirable » doit toujours être investigué avec un vétérinaire et un comportementaliste (ou un vétérinaire comportementaliste) : il peut en effet traduire un besoin, un inconfort ou une difficulté. Un chat qui griffe le tapis plutôt que son arbre à chat, par exemple, peut simplement chercher une position moins douloureuse. Certains animaux deviennent aussi plus anxieux ou plus réactifs avec l’âge ou certaines conditions médicales ; il est alors important d’en comprendre la cause plutôt que de sanctionner, au risque d’abîmer la relation et de ne pas régler la problématique.

La stimulation cognitive et physique doit se poursuivre, mais en s’adaptant aux capacités de l’animal. Les « puzzle feeders »(ou gamelles interactives, des bols où les animaux doivent résoudre des jeux pour avoir leur ration) restent intéressants, à condition d’être choisis en fonction de son état : un tapis de fouille, une gamelle interactive à pousser du nez seront préférables à un système demandant des mouvements complexes des pattes. Les jeux, les apprentissages et les petits entraînements restent bénéfiques ; il suffit parfois de raccourcir les séances et d’utiliser des récompenses très appétentes (petits morceaux de blanc de poulet ou de saucisses…).

Chien dans un sac
L’utilisation d’un sac peut permettre à votre animal de prolonger son accès à l’extérieur.
Treddy Chen/Unsplash, CC BY

Les promenades peuvent être adaptées notamment en utilisant des sacs confortables et sécuritaires pour porter le chien lorsqu’il est trop fatigué, que ce soit pour une partie ou l’ensemble de la balade, l’important étant de continuer à ce que l’animal ait accès à l’extérieur.

L’alimentation joue enfin un rôle majeur dans l’accompagnement des animaux âgés. Le vieillissement entraîne une modification de la digestion et une perte progressive de masse musculaire. Il est donc recommandé de privilégier une alimentation facilement digestible, dont l’odeur et le goût attirent votre animal, et formulée spécifiquement pour les besoins des seniors. Les rations de viande crue sont à éviter : elles sont souvent déséquilibrées en minéraux, ce qui peut être délétère pour les animaux âgés, particulièrement sensibles aux excès de phosphore ou aux rapports calcium/phosphore inadaptés. Elles présentent également un risque sanitaire accru alors que leur système immunitaire est moins performant.

En revanche, combiner une alimentation sèche (croquettes) et humide (terrine, mousses…) est souvent bénéfique. Une ration cuite et faite maison (en suivant les conseils d’un vétérinaire) peut aussi aider un animal à retrouver l’appétit. Et pour les plus difficiles, une astuce simple peut suffire : tiédir légèrement l’aliment humide pour en renforcer l’odeur et la rendre plus attirante.

À quel moment faire intervenir le vétérinaire ?

Les visites de suivi chez le vétérinaire restent indispensables, notamment pour maintenir à jour le protocole vaccinal et le déparasitage. Avec l’âge, le système immunitaire perd en efficacité : un animal senior est donc plus vulnérable et nécessite une protection régulière contre les maladies infectieuses et les parasites.

Les consultations de gériatrie ont pour objectif de suivre l’évolution du vieillissement qui est propre à chaque individu. La première est souvent la plus longue : elle permet un échange approfondi et inclut, lorsque nécessaire, des examens complémentaires. Ces premiers éléments serviront de référence pour les visites suivantes. L’idéal est d’entamer ce suivi dès le début du « troisième âge ». La fréquence des consultations dépend ensuite de la trajectoire de l’animal : tous les six mois si des signes de fragilité apparaissent, ou une fois par an si son état reste stable.

L’enjeu n’est plus seulement d’allonger la durée de vie de nos compagnons, mais surtout de prolonger leur vie en bonne santé, en préservant leur qualité de vie le plus longtemps possible – une démarche qui rejoint celle adoptée pour les humains et chats âgés : comment les accompagner pour un vieillissement sain ? Les conseils pratiques de chercheurs en sciences vétérinaires (alimentation, aménagement, comportements à surveiller, etc.)

The Conversation

Sara Hoummady est membre de l’AFGASP (Association Française de Gériatrie Animale et de Soins Palliatifs). Elle a reçu la bourse de la FVE (Federation Veterinaire Européenne) pour ses travaux sur le vieillissement félin. Elle a fait partie d’un comité de réflexion sur le vieillissement sain chez le chien et le chat organisé par un petfooder.

– ref. Votre chien ou chat vieillit ? Des gestes simples pour prolonger sa qualité de vie – https://theconversation.com/votre-chien-ou-chat-vieillit-des-gestes-simples-pour-prolonger-sa-qualite-de-vie-270489

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Les champignons d’Ötzi, l’homme des glaces du Néolithique

Source: The Conversation – France (in French) – By Hubert Voiry, Mycologue, Muséum national d’histoire naturelle (MNHN)

Amadouvier, Polypore du bouleau et Ötzi CC BY

On l’oublie trop souvent mais les champignons ont accompagné l’histoire de l’humanité : médecine, géopolitique, psychologie, architecture, gastronomie, ils s’invitent dans de nombreux champs de nos vie depuis le Néolithique.

Dans cet extrait de son ouvrage 10 champignons qui ont changé la vie des hommes (Éditions Actes Sud), le mycologue Hubert Voiry nous parle des deux champignons retrouvés par les archéologues dans la besace d’Ötzi, l’homme préhistorique découvert fortuitement en 1991 à 3200 mètres d’altitudes, dans les Alpes italiennes. Il tâche de comprendre pourquoi cet homme avait, avec lui des amadous et des polypores du bouleau

Ötzi portait un petit sac en cuir rempli de matière noire. Dans ce sac, il y avait aussi trois outils en silex et un os en forme de poinçon. Au début, on a pensé que la matière noire était de la résine et que ce sac était une sorte de “kit” de réparation d’outils. Or, la substance, une fois séchée, a montré une teinte virant au brun. L’examen microscopique de cet objet a révélé qu’il s’agissait de la chair d’un champignon, l’amadouvier (Fomes fomentarius). Cette chair brune que l’on trouve sous la croûte (la face supérieure) du champignon avait été travaillée manuellement pour obtenir un produit de consistance fibreuse que l’on appelle l’amadou. Mélangées à cette matière, on a détecté aussi des traces de pyrite. Silex, pyrite et amadou ainsi réunis permettent d’allumer le feu et de le conserver.

Ce n’est pas le témoignage le plus ancien de l’usage de l’amadou pour le feu. Celui-ci a en effet été retrouvé en grande quantité associé à des nodules de pyrite sur le site archéologique de Star Carr en Angleterre qui date de près de 10 000 ans. On a fait les mêmes observations dans les fouilles archéologiques de Maglemose au Danemark, site qui remonte à 8 000 ans. Il existe aussi des témoignages plus récents datant de l’âge du bronze en Suisse, dans les sites préhistoriques d’anciens villages lacustres. L’amadou a donc la propriété de produire et de transporter le feu. Contrairement à une idée reçue, les humains de cette époque ne frappaient pas deux silex l’un contre l’autre pour allumer un feu, car les étincelles résultant de leur percussion sont trop éphémères pour enflammer un combustible. Ils avaient recours essentiellement à deux techniques : celle de la friction avec du bois et celle de la percussion, vraisemblablement utilisée par Ötzi. Dans la première, on dispose un morceau de bois à la verticale d’un autre placé au sol. On frotte le morceau de bois sur l’autre en lui donnant un mouvement de rotation avec les mains. Cela produit de la sciure échauffée qui va donner quelques braises. Ensuite, il faudra les mettre en contact avec des brindilles sèches. Ce procédé n’a pas laissé de traces archéologiques. L’autre méthode consiste à utiliser, comme Ötzi, pyrite, silex et amadou. La percussion d’un morceau de disulfure de fer (pyrite ou marcassite) contre une roche dure comme le silex produit des étincelles. L’amadou au contact de l’étincelle est capable de s’embraser facilement du fait de sa structure fibreuse, et le feu peut couver longtemps, ce qui facilite son transport. Il reste à produire des flammes en mettant par exemple en contact l’amadou incandescent avec des herbes très sèches ou des fibres d’écorce.

Pour faciliter l’embrasement, on a perfectionné la technique. L’amadou est débité en tranches fines qui sont amollies à coups de maillet puis qui sont mises à sécher. Au cours des siècles, des traitements au salpêtre ou aux cendres ont été mis au point pour qu’il s’enflamme plus facilement. Le célèbre mycologue Christiaan Hendrik Persoon en donne la description dans son ouvrage Traité sur les champignons comestibles, contenant l’indication des espèces nuisibles paru en 1818. Il précise que les bûcherons des Vosges avaient une technique moins recommandable pour traiter l’amadou : ils enterraient les tranches du “bolet” et les arrosaient pendant un certain temps avec de l’urine.

À partir de l’âge du fer, les morceaux de disulfure sont remplacés par des briquets, petits objets en acier qui au Moyen Âge avaient une forme de crochet aplati. Actuellement, on peut se procurer, dans le commerce, ce type de briquet appelé aussi briquet à silex et ainsi reproduire les gestes de nos ancêtres en frappant l’acier sur un silex aiguisé. On recueille les étincelles avec un morceau d’amadou ou à défaut avec un morceau de coton carbonisé. Les briquets “à amadou” qui apparaissent vers 1840 ne contiennent curieusement pas d’amadou. Le nom a été repris, mais c’est une mèche de coton trempée dans une solution chimique qui joue le rôle de l’amadou.

De nos jours, l’amadou est encore utilisé de façon traditionnelle pour le transport du feu, comme en Autriche lors du Weihfeuertragen, littéralement “le transport de feu consacré”. Le samedi de Pâques, le prêtre catholique réunit les familles de paroissiens autour d’un feu qu’il bénit au cours d’une cérémonie. Ensuite, les enfants récupèrent les braises à l’aide de bidons métalliques et passent dans les maisons du village apporter le feu béni. Pour faciliter le transport, ils ajoutent aux braises des morceaux d’amadou. En plus d’être le polypore le plus efficace pour la fabrication et le transport du feu, grâce à sa chair, l’amadouvier a aussi des vertus médicinales et artisanales, voire spirituelles. Un peuple de l’île d’Hokkaidō au Japon, les Aïnous, procédait, en cas de maladie ou d’épidémie, à un rituel de fumée autour des habitations. Ils faisaient brûler toute la nuit des fructifications de F. fomentarius pour éloigner les démons. Un rite analogue était pratiqué en Sibérie chez les Khantys et en Amérique du Nord dans des tribus amérindiennes.

[…]

Le deuxième champignon retrouvé dans les affaires d’Ötzi est le polypore du bouleau, en latin : Fomitopsis betulina. Il se présentait sous forme de deux fragments enfilés sur une lanière de cuir. L’un de forme sphérique et l’autre de forme conique. Le polypore du bouleau, une fois séché, s’enflamme rapidement mais le feu ne couve pas. Ötzi ne l’a pas probablement pas utilisé pour le transport du feu, d’autant qu’il possédait déjà de l’amadou. Quel usage faisait-il donc des morceaux de ce polypore ?

Cette question a naturellement suscité des débats, dont sont ressorties deux grandes hypothèses. La première a été avancée par l’anthropologue italien Luigi Capasso : il suggère que l’Homme des Glaces était conscient de la présence de ses parasites intestinaux et les combattait avec des doses adaptées de Fomitopsis betulina. Ce champignon, qui est comestible – nous en reparlerons plus loin –, était probablement le seul vermifuge disponible à l’époque. L’autre hypothèse est défendue par la biologiste autrichienne Ursula Peintner : elle a fait le rapprochement avec certaines coutumes d’Amérindiens, rapportées par le biologiste américain Robert Blanchette. Ils possédaient des objets décorés avec des morceaux de forme ronde ou ovale d’Haploporus odorus, polypore à l’odeur très suave. Ces fragments étaient enfilés sur des lacets en cuir puis attachés aux tuniques sacrées ou aux colliers des guérisseurs. Ce polypore était aussi considéré comme ayant des vertus médicinales : on le faisait brûler pour produire une fumée agréable pour les personnes malades. Comme souvent dans les traditions, les aspects spirituel et médical sont mêlés. Concernant l’Homme des Glaces, nous avons bien noté que les bouts de F. betulina étaient enfilés sur une lanière de cuir de façon élaborée. S’il s’était agi d’un simple transport, ils auraient été placés sans perforation dans un récipient. On peut donc penser que les morceaux de F. betulina jouaient un rôle spirituel et médicinal. Robert Blanchette évoque aussi l’importance d’un autre champignon, Fomitopsis officinalis, aux propriétés médicinales pour les Amérindiens et leurs chamanes qui l’appellent “le pain des fantômes”. Les chamanes utilisaient des masques sculptés dans ces polypores pour effectuer des rites destinés à guérir certaines maladies. À leur mort, les masques étaient placés à la tête de la tombe et protégeaient l’esprit des chamanes. En Autriche, des fructifications de polypore du bouleau étaient sculptées pour protéger les animaux de ferme de la malchance. Le fragment conique du polypore d’Ötzi pourrait évoquer une sculpture qui n’aurait pas été très bien conservée. On pourrait donc considérer qu’Ötzi était un chamane qui portait sur lui, comme un talisman, ces deux fragments d’un champignon aux vertus médicinales et spirituelles. Rappelons que les affaires d’Ötzi n’ont pas été pillées, ce qui laisse supposer qu’on ne voulait pas s’approprier ses objets : c’était peut-être un personnage important.

The Conversation

Hubert Voiry est l’auteur de l’ouvrage « 10 champignons qui ont changé la vie des hommes », publié aux éditions Actes Sud dont ce texte est tiré.

– ref. Les champignons d’Ötzi, l’homme des glaces du Néolithique – https://theconversation.com/les-champignons-dotzi-lhomme-des-glaces-du-neolithique-270020