The six books that make up the shortlist for this year’s Stella Prize consider the problem of violence – both personal and cultural – in very different ways. The abusive ex-husband, the heavy boot of the law, the brutality of invasion, the pressures of isolation and loss.

But hearteningly, each book also has a bright thread of kindness, the richness of natural and built environments – and the consolations of poetry. Even when these narratives are desperately bleak, there is always a shard, at least, of light.

The Stella Prize, established after a long period when women writers were largely overlooked by the Miles Franklin Literary Award, focuses on diversity of form as well as authorship, creating a luscious literary smorgasbord.

This year, that’s reflected in a shortlist that includes a poetry collection by a former Stella winner and a graphic novel by a formerly shortlisted author – as well as a grief memoir, a nonfiction reflection on war and violence, and two novels.

As former Stella chair of judges Kerryn Goldsworthy once said, “excellence is achievable in any form”. I agree: this decision has provided me the opportunity to read six excellent books, across a range of genres, all doing what they do exceptionally well.

The Rot by Evelyn Araluen

Evelyn Araluen’s new collection has already won the Victorian Premier’s Literary Award and a number of glowing reviews. Let me add mine. Many of the poems in this collection shimmer with energy. Many play with form, too, introducing a fresh poetic diction: lineated and prose poems, fragments of lyrical prose, numbered paragraphs.

Alongside this innovative use of language and line, Araluen introduces a kind of hermeneutics: a mode of interpretation that (ideally) leads to deeper understanding. The Rot powerfully conveys what it feels like to live in the morass of late capitalism, racism, neocolonialism, sexism, incompetence and social media addiction – and offers a subtle road map out of all this.

Araluen is one of those rare poets who can take on political battles in poetry, without her poems being tendentious or soaked too deeply in ideology. The result here is a collection that left me nourished. She has reinvented a poetry of social and political crises for 21st century Australia.

Memorial Days by Geraldine Brooks

On United States Memorial Day in 2019, Geraldine Brooks was bluntly informed her husband, fellow writer Tony Horowitz, had died suddenly. This memoir opens with that moment, and the failures of the US system to offer even basic empathy, let alone practical support.

Writing with concision and clarity, Brooks tells the story of the long process of learning to go on, despite sometimes overwhelming melancholy. The account flicks back and forth between the first stunned months and her life three years later on Flinders Island, Tasmania, where she has retreated to spend her “own memorial days”. We see her re-inhabit that first shock, and the early stages of bereavement, while simultaneously remembering the delights of their shared life and drinking in the beauty of the island and its consolations.

This is a splendid example of a grief memoir. It maps out a productive approach to how to mourn – and how to begin living again.

Fireweather by Miranda Darling

In Fireweather, Miranda Darling continues the account of coercive control that began with Thunderhead. The novel’s blurb describes it as “feminist fiction”, and certainly it provides the perspective of a woman, Winona, who has lost custody of her children and is being menaced by her ex-husband.

But for me, it is the focus on language that characterises this novel. It deals creatively and persuasively with what words can do, how they engender sensation, and how they offer Winona a safe space during a season that combines apocalyptic bushfire with the catastrophic fallout from her marriage. Words are also her companions: the voices in her mind who offer running commentary, the voice of neighbourhood dog-cum-therapist Bruce, and her relationship with the plants she rescues.

If the writing were not so engaging, surprising and often very witty, the content would perhaps be too bleak. Yet the novel manages to explore how one might learn to face great disaster and remain at least semi-functional.

Cannon by Lee Lai

I am a fan of graphic novels, and Cannon is captivating, innovative and self-reflective. It is also a wryly critical commentary on the state of the cultural sector and its interest in monetising other people’s identity.

Lucy – aka Luce Cannon – and her friend Trish are the sort of outsiders who excite arts funders, being young, queer and Asian. Trish, a writer, is vampirising Lucy’s story for her own benefit; Lucy carries everyone else’s load, and is being crushed by it.

Most of the novel is presented in black-and-white cells, except for the snatches of horror movies the characters watch, which are in (blood) red, a creepy burst of colour in an otherwise monochrome book. Also creepy and “unnerving” (Lucy’s term) are the birds that loom whenever she is particularly overwhelmed.

While it offers a deeply thoughtful portrait of family and workplace stress, the story is often tender and very funny. Cannon is a persuasive comment on contemporary values.

58 Facets: On Law, Violence and Revolution by Marika Sosnowski

The Byzantine – that is, intricate, complex and unyielding – nature of law is a fact of life in pretty well every nation. So is the violence it legitimises, along with the reduction of individuals to official documents. This remarkable book works thoughtfully and convincingly through what this means for everyday people, living what should be everyday lives.

Marika Sosnowski is particularly equipped to explore this topic, as the descendent of Holocaust survivors, a researcher in Assad’s Syria and resident of an Australia that built a legal framework for cruelty toward asylum seekers. The account she provides of the damage inflicted, and the overt and everyday acts of resistance against it, sounds as though both dictatorial and democratic regimes have been scripted by Kafka.

But the misery is leavened by charming anecdotes, snatches of poetry and an overall call to collectivity: to “open our hearts to the woundedness of ourselves and others, to how similar our stories really are, to the great potential we all carry for acts of everyday revolution”.

I Am Nannertgarrook by Tasma Walton

I Am Nannertgarrook could have been a case study for Sosnowski’s discussion of law and violence. This novel focuses on historical violence – the brutal invasion of the Australian continent by European (mostly British) sailors, sealers and whalers, who were in fact acting to some extent under the protection of the law.

The murder and abduction of Indigenous people, and the predatory destruction of the environment they had tended for so long, are presented in horrifying closeup. The women and their children who occupy this novel have moments of comfort and consolation offered by Country, and by the more-than-human beings that inhabit it. Otherwise, they live with unrelenting horror and misery.

And though so much was lost through this violence, the narrative insists on the continuity of culture. The generous use of untranslated Indigenous language (there is a glossary at the back of the book) and the richly textured descriptions of traditional practices and values are deep reminders of the things that matter.

Jen Webb has received funding from the Australian Research Council.

If you travel around Australia, you will find an incredible diversity of lizards.

The three-toed snake-tooth skink (Saiphos reticulatus), for example, is a peculiarly long and stumpy legged reptile that burrows in rainforest and is covered in a brilliant orange and black-banded pattern. Alpine water skinks (Eulamprus kosciuskoi) are incredibly cold-tolerant and mottled with black and greenish yellow, like mossy rocks in mountain streams. Prickly forest skinks (Concinnia queenslandiae) are delightfully chunky-headed, spiky, armoured rainforest gems.

These lizards are all members of Australia’s largest evolutionarily related group of vertebrate animals, known as the Sphenomorphini. Their ancestors arrived in Australia some 28 million years ago, likely crossing land bridges and rafting across islands from Southeast Asia during glacial periods when sea levels were lower.

In a new paper, colleagues and I describe the most complete and detailed evolutionary tree of this group to date. This helps us to understand why there is such a mountain of species diversity within this group. A crucial clue is in the climate.

Building the evolutionary tree

Previous estimates in Sphenomorphini lizards concluded there were about 270 species in the group.

For our new study, we gathered more than 5,000 genetic identifiers to build a “species tree” of the entire group that reveals a total of at least 314 member species.

Our evolutionary tree shows most modern Sphenomorphini genera in Australia seem to appear in a six-million-year burst.

The timing of this burst is telling. It coincides with the Early Miocene – a climatically tumultuous period roughly 23 million to 16 million years ago, marked by the expansion of Antarctica’s ice sheets.

Australia, which by then had broken off from the southern supercontinent of Gondwana, saw a significant reduction in rainfall. As rainforest declined, the continent became more arid.

This suggests climatic changes may have driven the diversification of Sphenomorphini, with new species forming in response to the changing conditions.

This raises the question: how exactly did the new species form?

While several processes are known to drive the evolution of new species (such as sexual selection and competition), two major forces appear to be crucial to the story of the Sphenomorphini.

One is known as “allopatric speciation”. This is when a new species forms by the simple physical splitting of a population. Over millions of years, each population accumulates enough mutations via simple chance that if they were ever to meet again they would be too different to interbreed.

The second major force is known as “ecological divergence”. This is when populations of a single species develop niche traits in response to different environmental conditions. The populations now have differing selective pressures. Eventually, they stop mating with each other and enough different mutations accumulate to create an entirely new species.

The exact role of each of these forces is still unclear and will be the focus of our future research.

Heeding the warnings

Lizards are a massive component of the storied history of life on this planet. Now that we are slowly unravelling the mysteries of their evolution, we should perhaps heed the warnings.

In the Sphenomorphini, the details seem to paint a picture of arrival, climatic change likely accompanied by extinction and diversification, and for some, persistence in the face of a changing environment.

But bear in mind, the climate shifts that upended the Australian rainforest domination and led the Sphenomorphini to generate such diversity were incredibly slow.

Much changed in the 12 million years between the so-called early Miocene and middle Miocene climatic events. Yet global temperatures only declined around 2°C–3°C.

An equivalent degree of warming in only a mere few centuries would likely be catastrophic for these remarkable creatures – along with so much other life on Earth.

Janne Torkkola receives funding from Griffith University and Queensland Museum.

Every Friday morning in a community hall near Fremantle, something quietly extraordinary happens.

Chairs are arranged in a rough semicircle. Someone has brought a tray of biscotti from a recipe carried, unchanged, from Vasto, in the Abruzzo region of Italy. An organetto, a small button accordion common in southern Italian folk music, opens with a tarantella, a fast and joyful southern Italian dance tune. Before the first verse has ended, a dozen voices have joined. Some are strong. Some waver. All are unmistakably present.

Later, with the strumming of a guitar, the group finds its way to O Sole Mio. One man, who, according to his wife, barely talks anymore, closes his eyes and sings every word without hesitation. A woman in her 80s reaches for the hand beside her. When someone misses an entry, the laughter becomes part of the song.

As a researcher working with Italian migrant communities, I have been watching scenes like this for more than 15 years.

I have become convinced of something aged care policy has been relatively slow to recognise: the community choir is one of the most powerful cultural institutions in multicultural Australia, and we are at risk of losing it.

Italy has one of the richest choral traditions in the world. When Italian migrants arrived in Australia in the post-war decades, they planted vines, built parishes and founded social clubs. At the heart of many of those clubs was a choir.

These were not simply hobbies or nostalgic habits. They were acts of cultural survival, quiet assertions of who these men and women were in a country that often expected them to become someone else.

Reaching people through song

More than 411,000 Australians are currently living with dementia, and numbers are projected to more than double by 2058. More than one in four people living with dementia in Australia come from culturally and linguistically diverse backgrounds.

For migrants living with dementia, memory loss weakens the link between language, culture, and the ability to express and be recognised as belonging.

As the condition progresses, it strips away the most recently acquired language first. Migrants who spent decades speaking fluent English may revert to the dialect of their childhood village, leaving them unable to communicate with carers, other residents or sometimes their own families.

But, as I have witnessed again and again, song can sometimes reach people in ways conventional care struggles to.

In a project I conducted at a community-based aged care centre in Fremantle, one woman, Nina*, had largely stopped communicating. She sat quietly through most sessions. But when a Calabrian lira was played, a traditional bowed string instrument used by shepherds in Calabria, something shifted immediately. Its sound was ancient and deeply earthly, carrying something of the mountains and pastures and communal life of a world she had left 60 years earlier. Her face changed. Her hands began to move. She hummed, then sang, every word clear, every note in place.

Familiar songs are often preserved in what is known as procedural memory: the same deep-rooted system that remembers how to ride a bike or tie a shoelace. This type of memory is far more resistant to dementia than the memory that stores recent events and languages learned later in life.

The art of witnessing

There are several words and phrases sociologists use to describe what I am witnessing.

“Habitus” is a form of cultural “muscle memory” we build over a lifetime. When Italian migrants sing songs they first heard as children they are re-enacting something written into the body through years of shared practice.

“Collective effervescence” is that electric feeling when a group of people share an intense experience together and, for a moment, feel like one. The community hall near Fremantle becomes, for those two hours each Friday, something closer to sacred space: the Italian tricolour on the wall, the smell of food from the kitchen, a dozen voices locking into harmony.

“Embodied selfhood” is the idea that who we are is expressed not only through conscious thought, but through the body itself, in gesture, movement and interaction.

I see all these elements in action every Friday morning.

A new way for ageing

The choir I helped establish three years ago in Fremantle was built on the conviction that culturally specific music is not a luxury in aged care, but an ethical obligation.

Second- and third-generation Italian-Australians are now joining it.

One woman, Josephine* comes every Friday with her mother, who has dementia. Josephine told me “this is where she comes alive”.

The wife of the man who barely speaks anymore told me when he leaves the choir on Friday afternoon he walks differently. He stands taller.

Australia’s aged care system is undergoing significant reform. The question of what meaningful care looks like for a diverse ageing population is urgent, and so far, largely unanswered.

The Italian community choir in Fremantle has been answering that question every Friday morning for a few years now. It would be worth listening.

*Names have been changed.

Simone Marino 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.

Australia’s High Court will today hear its first ever climate case. It could have real implications for fossil fuel producers across the country.

The nation’s highest court has been asked to decide whether decision-makers must consider the likely climate impacts of fossil fuel projects on the communities where the mines operate.

The case revolves around a single coal mine in New South Wales, but it could have a much wider impact. When the High Court makes a ruling, it sets binding legal precedents. The outcome could directly shape how coal and gas projects are assessed in NSW – by requiring local climate impacts to be taken into account – and influence other states and territories.

This case comes after the International Court of Justice last year found nations are legally obliged to prevent harms caused by climate change. Recent advances in climate attribution science make it possible to link emissions from individual fossil fuel projects to measurable climate damage, such as extreme heat, heat-related deaths and coral reef loss.

We won’t know the legal outcome for some time. But one thing is certain – this case will have influence.

What’s this case about?

In 2021, coal miner MACH Energy sought approval from NSW authorities to keep its Mount Pleasant Coal mine open until 2048 and expand operations.

The extension would make Mount Pleasant the biggest open-cut coal mine in the state and result in an estimated 406 million tonnes more mined coal. Of this, 98% would be exported and burned overseas. These exported emissions are known as “Scope 3” emissions. They don’t count towards Australia’s domestic emissions tally.

The NSW Independent Planning Commission approved the extension of the mine in 2022, after considering the climate effect of the remaining 2% of emissions occurring within Australia but not the 98% burned overseas.

In 2022, a local community group challenged the approval, arguing the planning commission had failed to consider the likely impacts of Scope 3 emissions in contributing to local environmental impacts. Possible impacts include heatwaves, bushfires, droughts and floods.

The community group lost at the NSW Land and Environment Court, but won on appeal last year. In its findings, the NSW Court of Appeal held that while climate change is a global phenomenon, the planning commission was still required to consider the causal link between the project and likely local impacts of climate change.

MACH Energy appealed to the High Court, arguing the law does not require decision-makers to consider local environmental impacts when assessing a project or to conduct a causal inquiry as to the impacts of climate change.

What’s the context?

Australia is a giant gas and coal exporter. It ranks as the world’s second largest exporter of emissions, behind only Russia.

Australian state and territory governments routinely greenlight new fossil fuel export projects – even while working to cut domestic emissions.

To date, Australian courts assessing fossil fuel proposals have generally considered Scope 3 emissions, and the resulting climate impacts, under public interest assessments that evaluate whether a project provides a net benefit to the community.

For example, in the landmark 2019 Rocky Hill case, the NSW Land and Environment Court refused a proposed coal mine partly on climate grounds. It found the Scope 3 emissions of a mine must be considered in the public interest assessment.

One reason the MACH Energy High Court case is significant is because it’s the first time the courts have been asked to decide whether emissions from Australian coal burned overseas have to be considered in assessing likely impacts local to the mine site.

International law in the High Court?

The case is unfolding in the wake of last year’s landmark Advisory Opinion from the world’s top court, which found:

Failure of a state to take appropriate action to protect the climate system from […] emissions – including through fossil fuel production […] – may constitute an internationally wrongful act which is attributable to that state.

The International Court of Justice (ICJ) noted that establishing a causal link between emissions and climate harms “is not impossible”.

A rare unanimous decision of all 15 ICJ judges, these findings are authoritative. They represent a clear statement of the obligations of international law in relation to climate change.

The MACH Energy case will be the first time arguments about this international Advisory Opinion will be considered in Australia’s highest court.

Three international parties been granted leave to appear as amici curiae (“friends of the court”) at the High Court, in a sign of the global significance of the case. These include the Sabin Center for Climate Change Law and the Union of Concerned Scientists, both based in the United States.

What’s at stake?

The NSW policy landscape has shifted considerably since the coal mine extension was originally granted in 2022. In 2023, the state legislated emissions reduction targets and created the Net Zero Commission to advise whether departmental policies align with these targets.

Last year, the Net Zero Commission warned:

Continued extensions or expansions to coal mining in NSW are not consistent with the emissions reduction targets in the Climate Change Act or the Paris Agreement temperature goals it gives effect to.

In March this year, the NSW Labor government announced a ban on new coal mines – but kept the door open for future extension or expansion of existing coal mines. In April, the state government announced plans to open up new areas for gas exploration.

The High Court case is taking place against this complex policy backdrop. The court’s decision could establish a precedent that the full climate impacts of fossil fuel projects must be assessed in the local area, including emissions from fuel burned overseas.

Or it could keep the status quo, where the impact of Scope 3 emissions on the local area aren’t given significant weight.

Communities, boardrooms and governments will be watching closely when the High Court hands down its decision. Given Australia’s role as a major fossil fuel exporter, the world will be watching too.

Maria Nawaz 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.

New Zealanders like to think of themselves as an uncomplicated lot. So straightforward, in fact, that successful completion of a short test can determine one’s fitness to become a Kiwi.

At least, that’s the plan from Minister of Internal Affairs Brooke Van Velden, who has announced that from late 2027 part of the process of becoming a New Zealand citizen will entail scoring at least 75% in a 20-question multiple-choice test.

At one level, this makes sense. If someone wishes to become a citizen of New Zealand, it seems reasonable to expect them to know something of the place. (The same might be said of people who are already New Zealanders, but the test will apply only to aspiring citizens.)

On closer inspection, however, the proposed test raises questions that deserve close attention – particularly regarding methodology.

For the results of any test to be valid, the assessment method needs to be appropriate to the purpose of the exercise, which has to be carefully designed into the test questions themselves.

In other words, exactly what are we testing for? Van Velden has indicated the government is concerned “we have lost a sense of what it means to be a New Zealander”.

Accordingly, budding Kiwis will be quizzed on their comprehension of a range of topics including the contents of the Bill of Rights Act, human rights, voting rights and democratic principles, and New Zealand’s system of government.

Some of these lend themselves to precise, accurate responses. New Zealanders’ democratic and civil rights are, for instance, explicitly articulated in the Bill of Rights Act.

But designing a limited series of potential responses for complex, contested issues such as the nature of freedom of speech or respect for human rights poses any number of challenges.

Unintended effects

Like referendums, multiple-choice tests can unhelpfully reduce complex concepts to short, simple (if not simplistic) propositions. It is difficult to meaningfully assess someone’s appreciation of these intricate matters simply by requiring them to choose one option.

International research on the value of citizenship tests is not reassuring. There is some evidence people retain a limited amount of factual information for a short time following a test, but little indication preparing for and taking a test produces meaningful behavioural change.

On top of that, when the broader political and policy context is hostile to migrants (as is increasingly the case in New Zealand), such tests can produce the opposite of what is intended.

Research in the United Kingdom, for instance, has found some new citizens feel less connected with their new home having taken a test, perhaps out of anxiety or confusion about its relevance to their daily lives.

In short, learning about a host country may be useful in the short run, but rote learning to pass a multiple-choice test does not have meaningful, durable effects.

Historical amnesia?

Beyond those technical considerations lie questions about the actual resources available to people preparing to take the test, and the subtantive nature of the questions they will be asked.

Both will send clear signals about what it means to be a New Zealander. This takes on greater significance in the context of the current government’s rollback of Māori and Treaty of Waitangi influence in law and policy.

We might expect a citizenship test to include questions about the country’s constitutional arrangements. But Van Velden made no reference to te Tiriti o Waitangi when setting out the broad areas for inclusion in the test.

When Australia toughened its citizenship regime nearly a decade ago, Indigenous understandings of citizenship didn’t feature in a test about “Australian values”. The British test has been criticised for ignoring the legacy of imperialism in its former colonies.

What does not feature in the New Zealand citizenship test will matter every bit as much as what does. The risk is that it becomes an exercise in selective historical amnesia at the expense of an honest, comprehensive profile of the country.

“What it means to be a New Zealander” is no easy thing to define, let alone distil into a questionnaire that captures the country’s sense of itself. On the other hand, a simplified and partial version of national identity might be easier to convey in a short, multiple-choice test.

Richard Shaw 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.

The hoiho, also known as takaraka or yellow-eyed penguin, holds a special place in Aotearoa New Zealand’s natural identity.

Shy and solitary, with its distinctive yellow headband and pale eyes, it is one of the world’s rarest penguins and among the country’s most recognisable wildlife species.

For Ngāi Tahu, the hoiho is a taonga species closely tied to the health of the ocean and coastal ecosystems. The bird’s image appears on New Zealand’s $5 note alongside Sir Edmund Hillary, while its decline has become one of the country’s most urgent conservation stories.

That story has taken a new turn, with a just-published genomic analysis revealing the hoiho is not a single population, but three deeply distinct subspecies. Without immediate intervention, one of those subspecies could vanish within decades.

When one becomes three

Today, fewer than 115 hoiho breeding pairs remain on mainland New Zealand and Rakiura/Stewart Island.

Our research, supported by Genomics Aotearoa, shows these mainland birds are genetically isolated from subantarctic populations and have been evolving independently for thousands of years.

For decades, yellow-eyed penguins were broadly managed as two groups: mainland birds and subantarctic birds from the Auckland and Campbell Islands.

But by sequencing the genomes of 249 penguins from across their range, we discovered there are actually three distinct lineages with no migration between them. The mainland birds diverged from the southern populations between 5,000 and 16,000 years ago, long before humans arrived in New Zealand.

In partnership with Ngāi Tahu, we propose recognising three subspecies:

• hoiho murihiku: mainland and Rakiura hoiho
• hoiho motu maha: Auckland Islands hoiho
• hoiho motu ihupuku: Campbell Island hoiho

Recognising these three subspecies changes how we think about their conservation.

Rather than being interchangeable populations, these groups should now be considered distinct evolutionary lineages, each the result of thousands of years of adaptation to different environments.

Deadly disease driving decline

The mainland subspecies is already in crisis. Since 2019, chicks have been dying from a devastating disease known as respiratory distress syndrome, which causes severe breathing difficulties, lung damage and high mortality in young birds.

Previous work identified a likely viral cause: a newly discovered gyrovirus circulating in yellow-eyed penguins. Intriguingly, the virus is present across all regions, while severe disease appears concentrated in mainland birds.

Our analyses suggest there may be a genetic reason why. We identified certain immune and respiratory genes associated with disease susceptibility, including genes involved in antiviral immune responses.

This does not mean the disease risk is purely genetic. Habitat degradation, climate stress, fisheries bycatch, malnutrition and environmental change are all contributing to declining survival.

But it suggests mainland birds may be especially vulnerable to the virus because of their unique evolutionary history and shrinking population size.

The genomic warning signs are already visible. Mainland birds have lower genetic diversity and higher inbreeding than southern populations.

Yellow-eyed penguins have long been considered endangered, but our findings suggest extinction of the mainland subspecies is an even greater loss than previously thought.

The population has been declining for decades due to warming oceans, changing food availability, fisheries interactions, introduced predators and disease. Chick survival is now extremely poor, with fewer than 20% surviving to adulthood.

Without urgent action, extinction of the northern subspecies within a decade is now a realistic scenario. And because these penguins are genetically distinct, losing them means losing thousands of years of unique evolution.

How hoiho might be saved

Our findings have major implications for conservation management.

One possibility often discussed in endangered species recovery is “genetic rescue” – introducing individuals from other populations to increase genetic diversity.

But our results show the three hoiho subspecies are genetically very different, raising concerns about unintended consequences such as disrupting local adaptations.

That means conservation efforts may not be able to rely on future translocations between subspecies as a simple backup plan. Instead, preventing extinction of the mainland lineage must become the immediate priority.

That includes stronger fisheries protections to reduce bycatch, improved predator and habitat management, ongoing disease surveillance and research, greater investment in chick survival and rehabilitation, and stronger action to address marine ecosystem degradation and climate impacts.

Hoiho are also a taonga species for Māori and a major part of southern New Zealand’s wildlife identity. Their disappearance would be an ecological, cultural and economic loss all at once.

For many New Zealanders, yellow-eyed penguins feel like a permanent part of the landscape – a species that will always be there.

But genomics is telling us something sobering: the mainland hoiho is rapidly running out of time.

Jemma Geoghegan receives funding the Royal Society Te Apārangi, the Marsden Fund, the New Zealand Health Research Council, Genomics Aotearoa, the Ministry of Business Innovation and Employment and Te Niwha Infectious Disease Research Platform.

Janelle Wierenga receives funding from the Otago Shore and Land Trust and the Maurice Animal Foundation.

Joseph Guhlin receives funding from Genomics Aotearoa.

Peter Dearden receives funding from Genomics Aotearoa, Bioprotection Aotearoa, the Marsden Fund, and the Ministry of Business Innovation and Employment.

Why do some people maintain good memories and have healthy brains even as they age?

Research that my colleagues and I recently published in Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring, explored the effects and interactions of social, linguistic and endocrinological factors on cognitive health.

With Canada’s aging population, the question of brain health is a relevant one. The most recent census in 2021 indicated that one in eight Canadians is aged 70 or over, and there are 1.7 million who are age 80 or older. These numbers show a growing population of older adults at increased risk of cognitive decline, highlighting the need to examine protective factors.

Previous research indicates that bilingualism may be a possible protective factor. Notably, the 2021 census indicated that bilingualism is also increasing among Canadians, with four in 10 (41 per cent) speaking more than one language.

While bilingualism may be one piece of the puzzle, other cognitive or biological factors also influence brain health. Verbal memory — the ability to remember words — has been linked to cognitive resilience. The presence of sex hormones such as estrogen and testosterone, which are present in both men and women, may also influence how the brain ages.

Studying a trio of factors

The relationship between these three factors — bilingualism, verbal memory and sex hormones — has not been studied before. To address this gap, my colleagues and I conducted a new study in Canada. We found that bilingualism may interact with verbal memory and sex hormones to influence dementia risk in unexpected ways.

Our study included data from 335 older adults with mild cognitive impairment and 170 patients with Alzheimer’s disease drawn from the Comprehensive Assessment of Neurodegeneration and Dementia (COMPASS-ND) cohort, which is part of the Canadian Consortium on Neurodegeneration and Aging.

COMPASS-ND includes more than 1,200 Canadian adults aged 50–90 years recruited across more than 30 sites nationwide. Using this rich and current database, we examined how sex hormones, verbal memory and bilingualism jointly influence cognitive resilience, brain structure and blood-based markers of Alzheimer’s disease.

This article is part of our ongoing series The Grey Revolution. The Conversation Canada and La Conversation are exploring the impact of the aging boomer generation on Canadian society, including housing, working, culture, nutrition, travelling and health care. The series explores the upheavals already underway and those looming ahead.

We created a resilience index for each participant that incorporated sex hormones, verbal memory, bilingual proficiency, education, age and immigration status. Age, education, and immigration status were included as covariates because they may influence cognitive resilience through differences in language experiences, educational opportunities and sociocultural adaptation across the lifespan.

Each unit increase in the resilience index was associated with a significant reduction in the odds of dementia-related pathology. Higher resilience index scores were also linked to better performance on clinical diagnostic tools such as the Montreal Cognitive Assessment (MoCA), as well as lower levels of key markers associated with neurodegeneration and glial activation, a process in which the brain’s support cells become reactive in response to injury or disease.

Overall, bilingual participants showed the highest resilience index scores, but with notable differences in how these effects manifested across biological sex.

Our findings challenge the idea that risk and resilience can be understood by looking at biological or social factors in isolation. By studying bilingualism and sex hormones together, we reveal how these factors may interact to shape brain resilience.

Bilingualism and verbal memory

Another important finding of our study was related to verbal memory. Consistent with previous research, women showed better performance in verbal memory. This sex difference is clinically important because verbal memory is often used as a proxy for general cognitive function, meaning it can influence how dementia is diagnosed in women.

One might expect that bilingual women would be especially protected, since they have both the bilingualism benefit and strong verbal memory.

Surprisingly, our study found the opposite: bilingual men showed greater brain protection. Our findings suggested that a combination of two factors may be a mechanism behind enhanced verbal memory and cognitive resilience in aging men: aromatization — the conversion of testosterone into estradiol — and bilingual language experience.

In people with mild cognitive impairment, higher estradiol levels produced through aromatization, together with bilingualism, may work synergistically to protect verbal memory, making older bilingual men more resilient to cognitive decline and neurodegenerative pathology.

Overall, our study suggests that bilingual men may have greater resilience to neuropathology and that sex hormones could influence dementia risk in aging women. These findings underscore the need for more research on how sex hormones affect brain health, as well as the importance of using measures beyond verbal memory to improve the accuracy of cognitive decline diagnoses in Canada.

The research discussed in this article was supported by external funding from the Synapse Challenge award, Canadian Consortium on Neurodegeneration (CCNA). The funding period has now concluded.

For the first time since the Second World War, excluding the COVID-19 pandemic, public debt in the United States has surpassed the entire economy’s GDP. As of late March, debt held by the public reached US$31.27 trillion, just ahead of the GDP of US$31.22 trillion.

This threshold is often treated as a long-term fiscal issue, but the economic costs of this debt are now moving to the forefront. The most immediate pressure comes from the possibility that major foreign holders of American assets begin pulling capital out of U.S. markets.

Gulf states — whose confidence in U.S. fiscal and military protection has been shaken by the U.S.-Israel attacks on Iran — collectively hold roughly US$2 trillion in U.S. assets through their sovereign wealth funds.

Officials across the Gulf are already reassessing their positions. In March, one Gulf official said three of the four largest economies in the Gulf Cooperation Council were reviewing their sovereign wealth fund positions to offset the impact of the Iran war.

Why the U.S. cannot simply block a selloff

The U.S. has limited options to prevent foreign investors from selling. The freedom to enter and exit what the Federal Reserve Bank calls “the deepest and most liquid fixed-income market in the world” is exactly what makes U.S. assets attractive. That same openness creates a structural vulnerability.

The U.S. economy relies heavily on stretched asset valuations — elevated prices in stocks, bonds and real estate — where market values far exceed their underlying fundamentals.

When holders lose confidence and these inflated markets correct, a run is triggered and prices fall sharply, as happened in the 2008 financial crisis. The real economy ends up paying the price.

The present situation carries similar risks. If Gulf states start selling U.S. assets amid ongoing regional instability, falling prices would reduce the value of collateral across the system.

As leveraged institutions see their balance sheets weaken, they cut borrowing and sell assets. This pushes prices down further, setting off a chain reaction that spreads financial stress internationally.

Swap lines as a stop-gap

As these pressures build, one tool has come back into focus: central bank swap lines. These are arrangements between central banks that let countries access U.S. dollars without selling their American assets. Forced selling would push prices down and spread financial stress.

During the 2008 crisis, the Fed used swap lines as an emergency backup to extend dollar liquidity to banks and governments that suddenly needed it.

U.S. Treasury Secretary Scott Bessent recently said that several American allies in the Gulf region and Asia had requested swap lines, saying the arrangements would prevent the “disorderly” sale of U.S. assets.

But where does this dollar liquidity come from? For decades, the global role of the U.S. dollar allowed it to spend more than it earned, while other countries earned dollars through trade and invested them back into U.S. markets. Gulf states were central to this, using oil revenues to buy U.S. bonds, stocks, real estate and weapons.

This was part of a broader arrangement known as the petrodollar system, which traces back to a 1974 agreement between the U.S. and Saudi Arabia. Oil was priced in U.S. dollars, money flowed into the U.S. and in return Gulf countries received political and military backing.

This allowed the Federal Reserve to expand the money supply through quantitative easing at home and by extending liquidity into the global system through swap lines.

Though this can stabilize markets in the short term, it also deepens reliance on repeated intervention, buying time rather than resolving underlying pressures.

A fracturing arrangement

The petrodollar system only works as long as Gulf states keep sending money back into U.S. markets. Swap lines reverse that condition: dollars must now flow to the Gulf instead of from it.

Iran’s pressure campaign on Gulf states, including attacks on economic assets and leveraging the Strait of Hormuz, are creating uncertainty in oil markets, government budgets and regional stability.

Gulf sovereign wealth funds have responded by placing greater emphasis on liquidity and flexibility.

The United Arab Emirates’ exit from OPEC on May 1 shows how far the old energy-financial bargain has fractured. Gulf states now want more control over production, revenue and liquidity than the cartel system allows. The move also likely reflects U.S. pressure to bring oil prices down in the short term.

Read more: The UAE is leaving the OPEC oil cartel. What could that mean for oil prices?

That strategy cannot last. Lower oil prices may help the U.S. and other importers in the short run, but Gulf states still depend on strong revenues to fund budgets, sovereign wealth funds and diversification.

Gulf states are also signalling a willingness to expand the use of alternative currencies, including China’s yuan, for portions of their oil trade if regional instability disrupts dollar liquidity. The shift would merely accelerate the growing trend among emerging economies to move away from U.S. dollar dependence.

Extending swap lines to Gulf states may slow that process, but it may not be enough to reverse the currency diversification already underway.

A system under pressure

The global financial system was already moving toward greater fragmentation and weaker reliance on the U.S. dollar long before the Iran war.

U.S. President Donald Trump’s escalation with Iran has accelerated that process by shaking confidence in the political and military foundations that sustained the petrodollar system for decades.

Behind the scenes, policymakers are increasingly relying on swap lines, monetary expansion and emergency co-ordination measures to stabilize dollar liquidity and reassure allies. These tools were once reserved for acute crises, but are now becoming part of the normal functioning of the system and undermining U.S. asset credibility.

Underlying all of this is a global economy shaped by decades of financialization, growing dependence on inflated asset markets and mounting geopolitical rivalry, all of which are placing increasing strain on the old U.S. centred order.

Elliot Goodell Ugalde is affiliated with the Centre for International and Defence Policy.

Natalie Braun 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.

In November 2025, the Ontario government rushed through new legislation to dramatically restructure public drinking water and wastewater services without any public consultation.

The Water and Wastewater Public Corporations Act (WCA) authorizes the province’s minister of municipal affairs and housing to remove water and wastewater services from local governments and assign them to arms-length governance structures by classifying them as “water and wastewater public corporations (WCCs).”

Despite being buried among other controversial measures in the omnibus Bill 60, the WCA drew considerable public backlash. A broad-based coalition was formed, bringing together water workers, environmental organizations, physicians and anti-poverty activists to push back against what seemed like the stealth privatization of provincial water infrastructure.

In response, Premier Doug Ford’s government tabled amendments to restrict shareholders in WCCs to “a municipality, the Province of Ontario, the Government of Canada or an agent of any of them” under Bill 98, which is now in third reading.

But University of British Columbia law professor Joel Bakan has concluded these amendments don’t rule out privatization. The possibility of shares being held by the ambiguously termed “agent” of the state opens the door for any number of public-private configurations.

Financialization

While critical details might be clarified in upcoming regulations, a troubling picture emerges when connecting the dots. Whether the WCA leads to outright privatization, its proposed reforms are consistent with an insidious global push to make municipal water and sanitation systems more amenable to private investment. This essentially transforms them into tradeable assets.

This process, known as financialization, would erode the public health and social mandate of public water infrastructure, undermining the capacity of communities to cope with growing ecological and financial stresses.

Around the world, fierce public opposition has resulted in the termination or non-renewal of private contracts in hundreds of communities around the world. Even the staunchest proponents of privatization now view water as too politically risky and insufficiently profitable for private sector engagement.

At the same time, there has been a growing appetite for “bankable” water infrastructure projects in the face of growing economic uncertainty. In response, international financial institutions and other powerful entities are pushing for policy reforms to pave the way for the integration of water into global financial markets.

Extracting profit

Privatization is not a necessary precursor to financialization. Corporatized public utilities, argues British water researcher Kate Bayliss, can perform the same function of laying the groundwork and creating revenue streams that can eventually be captured by financial markets.

In fact the World Bank, the largest funder of water projects in the Global South, promotes reforms to publicly owned and operated utilities to improve their risk-return profiles for commercial investment. In other words, public institutions are restructured to absorb risk and shift costs to local communities in order to ensure greater extraction of private profit.

The Ontario legislation follows this model by dismantling municipal services and restructuring them into arm’s-length WCCs.

By removing water and sanitation services from local control, WCCs create a more streamlined system for profit generation. Key decisions — including finances, contracts and water rates — would be made by corporate boards with little direct accountability to communities.

Deepening existing inequities

Measures that generate value for shareholders will likely take precedence over public health and equity-related considerations.

As Brock University water management expert Lina Taing warns, the proposed consolidation of operations will ultimately undermine hard-won accountability provisions. It will also diminish the “site-specific knowledge” that is central to the multi-barrier approach developed in the aftermath of the Walkerton contaminated water crisis in May 2000.

The plan would take effect most immediately in Peel Region, one of the most racially diverse municipalities in the country. By 2029, jurisdiction over water and wastewater services will be transferred from Peel to its three lower-tier municipalities, which will then be required to deliver services exclusively through a newly created WCC.

The financial implications for Peel are deeply troubling. Water and wastewater infrastructure in Peel was built over decades with public funds. Under the new Ontario law, this infrastructure would be transferred to a WCC while Peel’s existing debt remains with the municipal government.

In other words, the assets are transferred while the liabilities stay behind. Peel will be left servicing legacy debt with no corresponding revenue stream, while revenues generated from water bills flow to WCC shareholders who bear no responsibility for that debt.

This is a textbook example of what scholars describe as risk socialization and profit privatization. Simply put, the public bears the burden while shareholders capture the reward.

Flint water crisis

In the words of American geographer Laura Pulido, racialized places often become the “testing ground for new forms of neoliberal practice.”

The Flint, Mich., water crisis also began with a state-level decision to place the city under emergency management.

The unelected city manager switched the city’s drinking water source to the highly contaminated Flint River as a cost-cutting measure, but failed to ensure the water was treated with corrosion inhibitors. This caused lead to leach from aging pipes and trihalomethanes (TTHMs) to form in tap water. TTHMs are a carcinogenic by-product formed when chlorine reacts with organic matter in water.

Likewise, ongoing challenges in First Nations communities underscore the inadequacies of top-down federal initiatives to resolve the drinking water crisis with blanket solutions that are inappropriate, inadequate or unacceptable to local communities.

A recent study found high concentrations of TTHMs in tap water samples from three Manitoba First Nations reserves as a result of treatment processes that weren’t suited to local environments and climate conditions.

Stripping communities of power

Both Bill 60 and Bill 98 align with broader efforts to expand the financialization of Ontario’s public infrastructure.

The Building Ontario Fund was established precisely for the purpose of including private capital in priority infrastructure projects. Unless challenged, the new legislation will strip communities of their power to shape services according to their needs, will make it easier to extract private wealth from public infrastructure and will erode the social mandates that make public water services central to building just, equitable and sustainable societies.

Experiences with water financialization in the United Kingdom and elsewhere show an intensified form of the harms associated with water privatization.

Water rates often rise sharply to generate returns for shareholders, while revenues are paid out as dividends instead of being reinvested in system maintenance and upgrades. Over time, this can erode environmental protections, social equity and labour rights.

The Ontario government is seeking public input on Bill 98 until this Thursday.

This is an opportunity for Ontario residents to join the Ontario Federation of Agriculture, the Canadian Union of Public Employees, the Canada Green Building Council, Environmental Defence Canada and many other organizations in demanding a better future for their water systems.

Meera Karunananthan sits on the boards of the Blue Planet Project and Peace Brigades International- Canada. They are both volunteer positions enabling her learn from and collaborate with water defenders, organizations and networks involved in frontline struggles for water justice around the world.

We’ve all heard the advice: eat your fruit and vegetables, get your vitamins, and stay healthy. For the most part, that guidance holds up. But some nutrients have a more complicated story, and vitamin B12 is a fascinating example.

Also known as cobalamin, B12 is essential for life. It helps the body produce red blood cells, keeps the nervous system functioning, and plays a central role in how cells copy and repair DNA.

B12 is found naturally in animal products such as meat, fish, eggs, milk and cheese. Some cereals and breads are also fortified with it, helping people who do not eat meat get enough. Most people following a varied diet get the recommended amount, but vegans, people with certain gut conditions and older adults who absorb nutrients less efficiently may need supplements.

Without enough B12, things can go wrong, sometimes seriously, especially if deficiency is not recognised and treated. Yet in recent years, researchers have been asking whether high levels of B12 intake or high levels of B12 in the blood could be linked to cancer.

Staying balanced

The body is constantly making new cells. Every time a cell divides, it needs to copy its DNA accurately. Vitamin B12 is critical to that process. When levels are too low, DNA can be copied incorrectly, leading to mutations that, over many years, may increase the risk of certain cancers, particularly colon cancer. This is why B12 deficiency is taken seriously.

A 2025 case-control study from Vietnam found what researchers described as a U-shaped relationship between B12 intake and cancer risk, with both lower and higher intakes associated with increased risk. Because this kind of study can show an association but cannot prove cause and effect, the takeaway is not that B12 is dangerous. It is that balance matters.

It might seem logical that if B12 helps healthy cells thrive, taking extra doses should offer extra protection against cancer. But research does not fully support this. Vitamin B12 supports cell growth generally, not only the growth of healthy cells. One concern is that, if pre-cancerous cells are already present, very high availability of growth-supporting nutrients such as B12 could, in theory, support their growth too. But this remains difficult to prove in humans.

Overall, studies of high-dose B vitamin supplements taken over long periods have not shown clear protective effects against cancer incidence or cancer deaths. One analysis did report a reduced risk of melanoma, but this was a cancer-specific finding rather than evidence that high-dose B vitamins prevent cancer generally. Some observational research has also suggested a slight increase in lung cancer risk linked to long-term, high-dose B6 and B12 supplementation, particularly among men and smokers, although this kind of study cannot prove that the supplements caused the cancers.

Doctors have noticed that many cancer patients show unusually high levels of B12 in their blood. This raises an important question: does elevated B12 contribute to cancer, or can cancer itself cause B12 levels to rise?

Research in 2022 concluded that high B12 in cancer patients is often an “epiphenomenon”. In other words, the vitamin appears alongside the disease but does not necessarily trigger it. Further research from 2024 reached a similar conclusion.

This effect is thought to involve two main mechanisms. First, tumours can affect the liver, which stores large amounts of B12. When the liver is damaged or under strain, it may release more B12 into the bloodstream. Second, some tumours may increase proteins that bind to B12 in the blood. This can push blood test readings higher without necessarily meaning the body’s cells are receiving or using more B12.

Useful indication

Researchers are also recognising that elevated B12 may not be a cause of cancer, but it could be a useful marker of whether cancer is present or progressing. A large 2026 study found that colon cancer patients with very high B12 levels survived a median of around five years, compared with nearly eleven years for those with normal levels.

Similar patterns have been found in oral cancer and in patients receiving immunotherapy, where elevated B12 has been associated with poorer outcomes. This means that unexplained, persistent high B12, especially when it is not caused by supplements, should not be ignored. It may point to liver disease, blood disorders or an underlying cancer that has not yet been detected.

For most people, this is not something to worry about. B12 from a normal diet containing meat, fish, eggs, dairy or fortified foods is not usually the issue: it is very difficult to consume too much B12 from food alone. Deficiency remains a more common and better-established problem than excess.

The concern is prolonged high-dose supplementation without medical advice, or a blood test showing persistently high B12 when someone is not taking supplements.

The broader message is simple: more is not always better. Cancer cannot be prevented by loading up on any single vitamin. Long-term habits matter more: eating a balanced diet, exercising regularly, avoiding smoking, protecting your skin and attending routine health screenings.

So what about vitamin B12? Get enough through food or supplementation if you need it, especially if you are vegan, older or have a condition that affects absorption. But leave the megadoses on the shelf unless a doctor advises them. With B12, as with many nutrients, the goal is not as much as possible. It is the right amount.

The authors 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.

If artificial intelligence (AI) systems shape decisions that affect people’s lives, they should do so fairly. This should be a given considering that potential applications for AI include automated hiring systems, as well as tools used in education, finance and criminal justice.

But ensuring the fairness of AI systems is far more complex than it might sound. Despite years of research, there is still no consensus on what fairness means, how it should be measured, or whether it can ever be fully achieved.

Fairness inherently depends on context. What counts as fair in one domain may be inappropriate or even harmful in another. In criminal justice, fairness may prioritise avoiding disproportionate harm to particular communities. In education, it may focus on equal opportunity and long-term outcomes.

In finance, it often involves balancing access to credit with risk assessment. Because AI systems must be formalised mathematically, researchers translate fairness into technical definitions expressed through metrics that specify how outcomes should be distributed across groups.

These metrics are useful tools, but they are not neutral. Each encodes assumptions about which differences matter and which trade-offs are acceptable.

Problems with the data

A deeper issue lies in the data itself. AI systems learn from historical datasets that reflect past decisions, institutional practices, and social inequalities. When a model is trained to replicate observed outcomes, such as hiring decisions or loan and mortgage approvals, it may reproduce existing injustices under the appearance of objectivity.

Optimising for one notion of fairness often means violating another. This tension is evident in automated loan approval systems. An algorithm may be designed so that applicants with the same predicted probability of default are treated similarly across demographic groups.

Yet one group may still be more likely to be incorrectly denied credit, while another may be more likely to receive loans they later struggle to repay. Fairness in predictive accuracy can therefore conflict with fairness in how financial risk and opportunity are distributed.

These differences often reflect structural inequalities embedded in the data the model is trained on. Groups that have historically faced barriers to credit, due to factors such as discrimination or exclusion from financial systems, may have thinner credit histories or lower recorded incomes.

As a result, models can treat socioeconomic disadvantage as a signal of higher risk, even when it does not reflect an individual’s actual ability to repay.

The same pattern emerges in hiring. If a company historically promoted fewer women into senior roles, a system trained to predict “successful” candidates may learn patterns that favour characteristics more common among men, even if gender is not explicitly included as an input. In both cases, the model does not invent bias, it inherits it.

A fundamental question is whether AI systems mirror the world as it was, or attempt to correct for known injustices.

The idea of fairness is further complicated by how it is assessed. Many assessments examine a single protected attribute, such as gender or race, in isolation. While common, this approach can obscure how discrimination operates in practice.

An automated hiring system might appear fair when comparing men and women overall, and fair when comparing ethnic groups overall, yet it might also consistently disadvantage older women from minority backgrounds.

Complex evaluation

People are defined by several characteristics that intersect, including age, ethnicity, disability, and socioeconomic background. Because these intersectional subgroups are often small and underrepresented in data, the harms they face may remain invisible in standard evaluations.

This invisibility has a direct technical consequence. When a subgroup is small, the model encounters too few examples to learn reliable patterns for that group and instead applies generalisations drawn from the broader categories it has seen more of, which may not reflect that group’s actual characteristics or circumstances.

Errors and biases affecting small subgroups are also less likely to surface in standard performance metrics, which aggregate results across all users and can therefore mask poor outcomes for minorities within minorities. Which means that those most at risk are therefore often the least visible.

These challenges suggest that fairness in AI cannot be reduced to better metrics or more sophisticated algorithms. Fairness is shaped by institutional context, historical legacies, and power relations.

Decisions about what data to collect, which objectives to optimise, and how systems are deployed are influenced by social and organisational factors. Technical fixes are necessary but insufficient. Meaningful approaches must engage with the broader context in which AI systems operate.

This includes involving interested parties beyond engineers and data scientists. People affected by AI systems, often members of marginalised communities, possess contextual knowledge about risks and harms that may not be visible from a purely technical perspective.

Participatory approaches, in which affected groups contribute to the design and governance of AI systems, acknowledge that fairness cannot be defined without considering those who bear the consequences of automated decisions.

Even when interventions appear successful, they may not remain so. Societies change, demographics shift and language evolves. A system that performs acceptably today may produce unfair outcomes tomorrow. In particular, recent advances in large language models, the technology underlying many widely used AI tools, add further complexity.

Unlike traditional systems that make specific predictions, these models generate language based on vast collections of historical text. Such datasets inevitably contain stereotypes and imbalances.

Fairness is therefore not a one-time achievement but an ongoing responsibility requiring monitoring, accountability, and a willingness to revise or withdraw systems when harms emerge.

Together, these challenges suggest that fairness in AI is not a purely technical problem awaiting a finite solution. It is a moving target shaped by social values and historical context.

Rather than asking whether an AI system is fair in the abstract, a more productive question may be: fair according to whom, under what conditions, and with what forms of accountability? How we answer that question will shape not only the systems we build, but the kind of society they help to create.

Michael Mayowa Farayola receives funding from Taighde Éireann Research Ireland grants 13/RC/2094_P2 (Lero) and 13/RC/2106_P2 (ADAPT) and is co-funded under the European Regional Development Fund (ERDF).

While some people can spring out of bed at six in the morning and go straight into their day, others prefer to wake up later as they’re most productive in the afternoon or evening. This difference is due to your chronotype – the biological tendency to prefer certain times of day for sleep, waking and activity.

But these aren’t the only factors affected by your chronotype. A growing body of research also suggests that your chronotype can affect the benefits you see from exercise.

People who naturally rise early and feel sharpest in the morning are “early chronotypes”, whereas those who prefer to wake later and function better in the afternoon or evening are “late chronotypes”. People who fall in between are “intermediate chronotypes”.

Your chronotype is determined by your circadian rhythms – the body’s natural daily cycles that repeat around every 24 hours. Although these are strongly influenced by our environment, they function even without external cues such as daylight and food. These rhythms affect our physiology, behaviour and health.

Our circadian rhythms are controlled by the body’s circadian system, which is made up of tiny biological clocks composed of proteins, which are found in organs and tissues. These clocks rely on genes that help coordinate when different processes happen, such as when we feel alert or sleepy.

The circadian system also influences many other bodily functions, including blood pressure, heart rate, blood sugar regulation and blood vessel function. As these factors are also affected by physical activity, this may explain why aligning your workouts to your natural chronotype can be beneficial.

Some studies support this, suggesting that the time of day people exercise can influence health outcomes – including cardiovascular fitness and reducing the risk of cardiovascular disease, obesity and some cancers.

However, as these were observational studies (which only show associations rather than cause and effect), they can’t definitively prove that the findings were solely caused by the timing of the exercise.

But a recent randomised controlled trial has investigated whether aligning workouts with chronotype could enhance the benefits of exercise. The researchers specifically looked at people who were at risk of cardiovascular disease.

Participants were grouped according to their chronotype, which was measured using a specialist questionnaire. Morning types exercised between 8–11am and evening types exercised between 6-9pm. A third group exercised at the opposite time to their chronotype (morning types in the evening and evening types in the morning).

Participants whose exercise was aligned with their chronotype experienced greater improvements in blood pressure, aerobic fitness, blood glucose, cholesterol and sleep than participants whose training times were misaligned with their chronotype.

But though these improvements show that timing exercise to your chronotype can enhance its health benefits, there are a couple of important nuances.

Even the group that exercised at the supposedly wrong time still experienced health benefits, showing that exercise is beneficial even when it doesn’t align with your chronotype. The study also did not include intermediate chronotypes, who make up around 60% of the adult population. For these people, the timing of exercise may be less important.

Based on the available evidence, exercise timing appears to be a meaningful consideration, particularly for people who are strong morning or evening chronotypes.

Beyond your chronotype

So how do you know your chronotype?

Most people have an intuitive sense of this based on when they naturally prefer to sleep and wake. However, work schedules and care-giving responsibilities often force us into routines that conflict with our chronotype. Over time, this makes it harder to be sure of your chronotype.

For this reason, researchers developed a questionnaire to help you determine your chronotype. The 19 questions include what time you feel you’re at your peak and how easy you find it to wake up in the morning.

Once you have a clearer sense of your chronotype, you can start thinking about when to schedule your training.

However, chronotype isn’t the only factor that can affect training and how you respond to exercise. This is good news for those who may not be able to align workouts with their chronotype.

For instance, body temperature usually peaks in the afternoon regardless of chronotype, which enhances muscle function. This is why strength, speed and coordination tends to be best in the afternoon, making it a prime window for resistance training and technical practice for most people.

Habitual training time can also shift performance over time as the body adapts to the time you regularly train. So even if you’re naturally a night owl, consistent morning training may eventually make you perform better at that time.

Another critical factor to consider when deciding when to workout is sleep.

If you haven’t slept well the night before, research suggests it’s better to exercise earlier in the day, regardless of your chronotype. This is because the drive to sleep, known as “sleep pressure”, builds steadily from the moment you wake up and peaks just before you fall asleep. By evening, growing sleep pressure makes exercise feel harder and can impair your performance.

Exercising late in the evening can also reduce sleep quality, particularly when the session is intense. As a general rule, leave at least a two-hour gap between exercise and bedtime.

There’s no single best time to exercise that works for everyone. While the evidence on the long-term health benefits of matching exercise time to chronotype is growing, some principles apply broadly.

Peak performance varies by chronotype, and matching your workout time to yours may help you train harder and achieve better health benefits. However, any exercise is better than none – regardless of timing.

If you’re a night owl but can only train in the morning, a warm-up is essential. Wear extra clothing and start with 10-15 minutes of light aerobic activity to gradually increase body temperature and increase alertness.

If evenings are your only option, opt for moderate or low-intensity activities (such as yoga or a jog) to avoid disrupting sleep.

Paul Hough 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.