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November 10, 2025

We asked teachers about their experiences with AI in the classroom — here’s what they said

Source: The Conversation – Canada – By Nadia Delanoy, Assistant Professor, Leadership, Policy, and Governance and Learning Sciences, Werklund School of Education, University of Calgary

“As much as I appreciate professional learning, when it is all about what tools to use, it misses the mark,” said one teacher in a study about AI in classrooms. CC BY-NC

Since ChatGPT and other large language models burst into public consciousness, school boards are drafting policies, universities are hosting symposiums and tech companies are relentlessly promoting their latest AI-powered learning tools.

In the race to modernize education, artificial intelligence (AI) has become the new darling of policy innovation. While AI promises efficiency and personalization, it also introduces complexity, ethical dilemmas and new demands.

Teachers, who are at the heart of learning along with students, are watching this transformation with growing unease. For example, according to the Alberta Teachers’ Association, 80 to 90 per cent of educators surveyed expressed concern about AI’s potential negative effects on education.

To understand comprehensive policy needs, we must first understand classrooms — and teachers’ current realities.

As a researcher with expertise in technology-enhanced teaching and learning at the intersections of assessment, leadership and policy, I interviewed teachers from across Canada, with Erik Sveinson, a Bachelor of Education student. We asked them about their experiences with generative AI (GenAI) in the classroom.

Their stories help contextualize a reality of AI in a K-12 context, and offer insights around harnessing AI’s potential without harming education as a human-centred endeavour.

AI policy and teaching wisdom

This qualitative study involved 10 (grades 5 to 12) teachers from Alberta, Saskatchewan, Ontario and British Columbia.

We recruited participants through professional learning networks, teacher associations and district contacts, seeking to ensure a variety of perspectives from varied grade levels, subjects and geographic locations.

We thematically coded interview data, and then cross-referenced this with insights from a review of existing research about GenAI use in K-12 classrooms. We highlighted convergences or tensions between theories about assessment, teaching approaches in technology-enhanced environments, student learning and educator practices.

Across interviews, teachers described a widening gap between policy expectations and the emotional realities of classroom practice.

What we heard

The following themes emerged from our interviews:

1. The assessment crisis: Longstanding tools of assessment, such as the essay or the take-home project, have suddenly become vulnerable. Teachers are spending countless hours questioning the authenticity of student work.

All teachers interviewed consistently said they struggled with their current assessment practices and how students may be using GenAI in work. Confidence in the reliability of assessments have been challenging. The majority of teachers shared they felt they needed to consider students cheating more than ever given advancing GenAI technology.

2. Equity dilemmas: Teachers are on the front lines of seeing firsthand which students have unlimited access to the latest AI tools at home and which do not.

3. Teachers perceive both opportunities and challenges with AI. Great teaching is about fostering critical thinking and human connection. Ninety per cent of teachers interviewed faced complex challenges relating to equity and how best to support critical thinking in the classroom while building foundational knowledge. In particular, middle and high school teachers in core subject areas indicated students were using GenAI tools in their own time outside class without ethical guidance.

‘One more thing piled on’

One teacher from central Alberta said:

“AI is definitely helpful for my workflow, but right now it feels like one more thing piled onto an already impossible workload. The policy says, ‘embrace innovation,’ but where’s the guidance and support?”

Classrooms are dynamic ecosystems shaped by emotion, relationships and unpredictability. Teachers manage trauma, neurodiversity, language barriers and social inequities while delivering curriculum and meeting student achievement expectations.

Teachers say there’s little recognition of the cognitive load they already carry, or the time it takes to vet, adapt and ethically deploy AI tools. They say AI policies often treating educators as passive implementers of tech, rather than active agents of learning.

A high school teacher from eastern Canada shared:

“AI doesn’t understand the emotional labour of teaching. It can’t see the trauma behind a student’s meltdown. As much as I appreciate professional learning, when it is all about what tools to use, it misses the mark.”

This perspective highlights a broader finding: teachers are not resisting AI per se; they are resisting implementation that disregards their emotional expertise and contextual judgment. They want professional learning initiatives that honour the human and relational dimensions of their work.

Burnout, professional erosion

This disconnect is not just theoretical, it’s emotional. Teachers are reporting burnout, anxiety and a sense of professional erosion. A 2024 study found that 76.9 per cent of Canadian educators felt emotionally exhausted, and nearly half had considered leaving the profession. The introduction of AI, without proper training or support, is compounding that stress.

There’s also a growing fear reported by the Alberta Teachers’ Association that, if not implemented properly with support for teachers new to the profession, AI could deskill the profession.

A teacher in Vancouver shared:

“I am a veteran teacher and understand the fundamentals of teaching. For beginner teachers, when algorithms write report cards or generate lesson plans, what happens to teacher autonomy and the art of teaching?”

Turning teaching into a checklist?

Overall, the interview responses suggest what’s missing from AI policy is a fundamental understanding of teaching as a human-centred profession. As policymakers rush to integrate AI into digitized classrooms, they’re missing a critical truth: technology cannot fix what it may not understand.

Without clear guardrails and professional learning grounded in teacher and student-informed needs, AI risks becoming a tool of surveillance and standardization, rather than empowerment.

This tension between innovation and de-professionalization emerged across many teacher responses. Educators expressed optimism about AI’s potential to reduce workload, but also deep unease about how it could erode their professional judgment and relational roles with students.

A northern Ontario teacher said:

“There is hope with new technology, but I worry that AI will turn teaching into a checklist. We’re not technicians, we’re mentors, guides and sometimes lifelines.”

Teachers fear that without educator-led frameworks, AI could shift schooling from a human-centred practice to a compliance-driven one.

Responsible AI policy

If we want to harness AI’s potential without harming education as a human-centred endeavour with students and teachers at the core, we must rethink approaches to AI innovation in education. That starts with listening to teachers.

Teachers must be involved in the design, testing and evaluation of AI tools. Policies must prioritize ethics, transparency and equity. That includes regulating how student data is used, ensuring teachers can ascertain algorithmic bias and ethical implications and also protecting teacher discretion.

Third, we need to slow down. The pace of AI innovation is dizzying, but education isn’t a startup. It’s a public good. Policies must be evidence-based and grounded in the lived experiences of those who teach.

Nadia Delanoy receives funding from the University of Calgary.

– ref. We asked teachers about their experiences with AI in the classroom — here’s what they said – https://theconversation.com/we-asked-teachers-about-their-experiences-with-ai-in-the-classroom-heres-what-they-said-265241

November 10, 2025

Why we used to sleep in two segments

Source: Radio New Zealand

For most of human history, a continuous eight-hour snooze was not the norm.

Instead, people commonly slept in two shifts each night, often called a “first sleep” and “second sleep.” Each of these sleeps lasted several hours, separated by a gap of wakefulness for an hour or more in the middle of the night. Historical records from Europe, Africa, Asia and beyond describe how, after nightfall, families would go to bed early, then wake around midnight for a while before returning to sleep until dawn.

Breaking the night into two parts probably changed how time felt. The quiet interval gave nights a clear middle, which can make long winter evenings feel less continuous and easier to manage.

The midnight interval was not dead time; it was noticed time, which shapes how long nights are experienced. Some people would get up to tend to chores like stirring the fire or checking on animals. Others stayed in bed to pray or contemplate dreams they’d just had. Letters and diaries from pre-industrial times mention people using the quiet hours to read, write or even socialise quietly with family or neighbours. Many couples took advantage of this midnight wakefulness for intimacy.

Literature from as far back as ancient Greek poet Homer and Roman poet Virgil contains references to an “hour which terminates the first sleep,” indicating how commonplace the two-shift night was.

How we lost the ‘second sleep’

The disappearance of the second sleep happened over the past two centuries due to profound societal changes. Artificial lighting is one of them. In the 1700s and 1800s, first oil lamps, then gas lighting, and eventually electric light, began turning night into more usable waking time. Instead of going to bed shortly after sunset, people started staying up later into the evening under lamplight.

Biologically, bright light at night also shifted our internal clocks (our circadian rhythm) and made our bodies less inclined to wake after a few hours of sleep. Light timing matters. Ordinary “room” light before bedtime suppresses and delays melatonin, which pushes the onset of sleep later.

The Industrial Revolution transformed not just how people worked but how they slept. Factory schedules encouraged a single block of rest. By the early 20th century, the idea of eight uninterrupted hours had replaced the centuries-old rhythm of two sleeps.

In multi-week sleep studies that simulate long winter nights in darkness and remove clocks or evening light, people in lab studies often end up adopting two sleeps with a calm waking interval. A 2017 study of a Madagascan agricultural community without electricity found people still mostly slept in two segments, rising at about midnight.

Long, dark winters

Light sets our internal clock and influences how fast we feel time passing. When those cues fade, as in winter or under artificial lighting, we drift.

In winter, later and weaker morning light makes circadian alignment harder. Morning light is particularly important for regulating circadian rhythms because it contains a higher amount of blue light, which is the most effective wavelength for stimulating the body’s production of cortisol and suppressing melatonin.

In time-isolation labs and cave studies, people have lived for weeks without natural light or clocks, or even lived in constant darkness. Many people in these studies miscounted the passing of days, showing how easily time slips without light cues.

Similar distortions occur in the polar winter, where the absence of sunrise and sunset can make time feel suspended. People native to high latitudes, and long-term residents with stable routines, often cope better with polar light cycles than short-term visitors, but this varies by population and context. Residents adapt better when their community shares a regular daily schedule, for instance. And a 1993 study of Icelandic populations and their descendants who emigrated to Canada found these people showed unusually low winter seasonal affective disorder (SAD) rates. The study suggested genetics may help this population cope with the long Arctic winter.

Research from the Environmental Temporal Cognition Lab at Keele University, where I am the director, shows how strong this link between light, mood and time perception is. In 360-degree virtual reality, we matched UK and Sweden scenes for setting, light level cues, and time of day. Participants viewed six clips of about two minutes. They judged the two minute intervals as lasting longer in evening or low-light scenes compared with daytime or brighter scenes. The effect was strongest in those participants who reported low mood.

A new perspective on insomnia

Sleep clinicians note that brief awakenings are normal, often appearing at stage transitions, including near REM sleep, which is associated with vivid dreaming. What matters is how we respond.

The brain’s sense of duration is elastic: anxiety, boredom, or low light tend to make time stretch, while engagement and calm can compress it. Without that interval where you got up and did something or chatted with your partner, waking at 3am often makes time feel slow. In this context, attention focuses on time and the minutes that pass may seem longer.

Cognitive behavioural therapy for insomnia (CBT-I) advises people to leave bed after about 20 minutes awake, do a quiet activity in dim light such as reading, then return when sleepy.

Sleep experts also suggest covering the clock and letting go of time measurement when you’re struggling to sleep. A calm acceptance of wakefulness, paired with an understanding of how our minds perceive time, may be the surest way to rest again.

Darren Rhodes is a Lecturer in Cognitive Psychology and Environmental Temporal Cognition Lab Director, Keele University, Keele University.

– Published by EveningReport.nz and AsiaPacificReport.nz, see: MIL OSI in partnership with Radio New Zealand

November 10, 2025

Canada loses its official ‘measles-free’ status – and the US will follow soon, as vaccination rates fall

Source: The Conversation – USA (3) – By Kathryn H. Jacobsen, William E. Cooper Distinguished University Chair, Professor of Health Studies, University of Richmond

Canada eliminated measles in 1998 but had a major outbreak in 2025. jure/iStock via Getty Images Plus

In the wake of a measles outbreak in Canada that has infected thousands of people over the past year, an international health agency revoked the country’s measles-free status on Nov. 10, 2025.

The Pan American Health Organization, which serves as the World Health Organization’s regional office for the Americas, made this announcement after the agency’s measles elimination commission met in Mexico City to review the latest public health data.

As a global health epidemiologist who studies the spread of infectious diseases, this change in status does not surprise me. Measles is highly contagious, and a drop in childhood vaccination rates in Canada and in other countries has left many children unprotected from the disease.

The resurgence of measles in Canada after decades with very low numbers of cases is not an isolated problem. The U.S. has also had large outbreaks of measles this year, and it will likely soon lose its measles-free designation as well.

The loss of measles elimination status is a symptom of a deeper issue: declining trust in public messaging about science and health, which has led to decreased vaccination rates and growing vulnerability to vaccine-preventable diseases.

What does it mean for a country to be measles-free?

Measles is one of the most contagious diseases on the planet. Before the measles vaccine was licensed for use in 1963, nearly every child got measles infection and more than 2 million children died from measles each year.

The vaccine decreased that risk dramatically. By 1968, five years after the vaccine became available, case counts in the U.S. had dropped by more than 95%. Cases in Canada also decreased substantially after the vaccine was introduced.

Tragically, about 100,000 children still die from measles each year even though a safe, effective and low-cost vaccine is available. Almost all of those deaths occur in low-income countries where many children do not have access to recommended vaccines.

The World Health Organization uses three labels to describe how well a country is preventing the spread of infectious diseases such as measles. A disease is said to be controlled when public health interventions such as routine childhood vaccinations significantly lower the rate of new infections. A disease is considered to be eliminated from a country when the only cases that happen are small outbreaks linked to international travel. And finally, a disease is deemed eradicated only after several years of no cases occurring anywhere in the world.

To achieve the status of measles elimination, a country must have no ongoing local transmission of the disease for at least one year. It will lose that status if it has a chain of cases that spread from person to person for more than one year.

Measles cases have occurred in every province in Canada in 2025.

Once a country has eliminated measles, there is almost no risk from the disease as long as vaccination rates stay high. But when vaccination rates drop, outbreaks will soon start happening.

What happened in Canada?

In 1998, the Pan American Health Organization confirmed that Canada had eliminated measles transmission. Two years later, the U.S. also gained the measles-free designation.

By 2016, every country in the Americas had achieved measles elimination status. The region lost that status in 2018 after outbreaks in Brazil and Venezuela, and then regained it in 2024.

But childhood vaccination rates have been falling worldwide, especially during and after the COVID-19 pandemic. To protect communities from measles outbreaks, about 95% of the population must be vaccinated against the disease.

In Canada, the percentage of 2-year-olds who have received at least one dose of measles vaccine dropped from about 90% in 2019 to about 82% in 2022 and 2023. As the number of unvaccinated people in the population increased, the risk of measles outbreaks grew.

After having only 16 total cases of measles nationwide between 2020 and 2023, the number of measles cases in Canada jumped to more than 100 in 2024 and more than 5,000 cases in 2025. Cases have occurred among infants, children and adults in every Canadian province in 2025, and two infants have died.

Fewer than 10% of the people who have gotten sick had been vaccinated against the disease.

What happens next?

It is likely that both the U.S. and Mexico will lose their measles-free designation in 2026, because both countries have had sustained outbreaks of measles since early 2025.

Although more than 90% of kindergartners in the U.S. are vaccinated against measles, that rate is too low to protect communities from outbreaks. An outbreak that started in Texas in January 2025 infected more than 760 people and caused the deaths of two children.

In total, more than 1,600 Americans in more than 40 states have gotten sick from measles in 2025. That is more cases than any year since 1992. More than 90% of the people who got sick were unvaccinated.

Mexico has also had thousands of measles cases this year, mostly among unvaccinated people.

Central America, South America and the Caribbean will retain their measles-free status for now. But the outbreaks in North America increase the risk of measles spreading to other countries.

Without a significant improvement in vaccination coverage and public trust in community health measures, many countries are likely to face more, and bigger, outbreaks of measles and other vaccine-preventable diseases in the coming years.

Kathryn H. Jacobsen 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. Canada loses its official ‘measles-free’ status – and the US will follow soon, as vaccination rates fall – https://theconversation.com/canada-loses-its-official-measles-free-status-and-the-us-will-follow-soon-as-vaccination-rates-fall-269090

November 10, 2025

What will it take to make Africa food secure? G20 group points to trade, resilient supply chains and sustainable farming

Source: The Conversation – Africa – By Wandile Sihlobo, Senior Fellow, Department of Agricultural Economics, Stellenbosch University

The Sustainable Food and Agricultural Systems work stream of the Business 20, a G20 engagement group, has endorsed three principles that it argues will contribute to the building of sustainable food systems and agriculture. The principles are increased trade, resilient supply chains, and sustainable agricultural practices.

Agricultural economist Wandile Sihlobo explains these three principles and how African countries can put them to good use.

What is global food security? How does it differ from food poverty?

Global food security is more comprehensive, seeking to address the challenges of access to food, nutrition, sustainability and affordability. The broad ambition of global food security is to ensure that countries, especially the G20 members, work collaboratively on initiatives that reduce global poverty levels. This reduction of poverty must be material at both national and at household level.

Achieving this goal will demand that each country’s domestic agricultural policy enables increases in food production, prioritises environmentally friendly production approaches, and eases trade friction. This will enable countries that cannot produce enough food to import it, and most importantly, do so affordably. Also, countries should ease the global logistics friction, removing tariffs and ensuring that a flow of agricultural products is smooth. This also includes the removal of export bans in certain cases. For example, in 2023, India banned the exports of rice and that caused a surge in global food prices.

It is for this reason that I have championed the approach of “achieving food security through trade”. Such an approach is essential in an environment characterised by trade friction, which generally increases transaction costs for all. Ultimately, the goal of improving global food security seeks to improve the living standards for all, with the focus on the poor regions of the world, mainly Africa, the Middle East and Asia.

How can increased trade, resilient supply chains and sustainable agricultural practices enhance food security?

These interventions are at the heart of easing costs. If trade friction (tariffs, non-tariff barriers and export bans) are eased, we are able to lower the transaction costs of getting the goods from the production areas to the consumption points affordably.

Resilient supply chains also mean that food can be produced, processed and transferred to consumption points with less friction even in times of natural disasters and conflicts.

Sustainable agricultural practices are at the core of the food system. Still, this does not mean a move away from improved seed cultivars and genetics, and elimination of agro-chemicals and other inputs. It mainly refers to using them better.

I have noted a troubling trend of activism that seeks to eliminate agricultural inputs, a path that would lead to lower agricultural productivity and output, and eventually worsen hunger. The key should be safe and optimal use of these inputs.

In the recent farm protests in the European Union, the EU’s regulatory approach to sustainable farming practices was one of the issues farmers raised as the major risk. They cited the EU’s Green Deal, which aimed to accelerate the reduction of the use of inputs, such as pesticides, fertilisers and certain other chemicals, that are critical for increased production.

In my view, the G20 should guard against activist moves that are dangerous to global food security.

What specific policies should countries, especially African nations, put in place to ensure the success of these principles?

South Africa and the African Union, which are both G20 members, should push for three broad interventions in agriculture to achieve the three G20 principles and boost food production that could benefit the African continent.

1. Climate-smart farming

First, there should be a strong call for sharing knowledge on climate-smart agricultural practices. These are new innovations and ways of farming that minimise the damage to crops caused by climate-related disasters like drought and heatwaves. This is important because Africa is very vulnerable to natural disasters.

For African agriculture to take off, governments must set up co-ordinated policies on how to respond to disasters. These responses must include everything African countries need to mitigate climate-related disasters, adapt to climate change, and recover quickly when disasters hit.

2. Trade reform

Second, Africa must push for a reform of the global trading system, and to improve food security in Africa through trade. South Africa already enjoys deeper access to agricultural trade with several G20 economies through lower tariffs and some tariff free access.

It is in the interests of all G20 members to ensure open trade among the nations of the world. Open agricultural trade enables countries to buy and sell agricultural produce at lower prices. This is vital in the current environment where some nations are taking a more confrontational approach to trade.

African countries whose agriculture is less productive, with generally lower or poor crop yields, may not benefit as much in the short term from open trade. They will, however, benefit in the long run.

3. Improve access to fertilisers

Third, Africa should continue prioritising discussions about improving fertiliser manufacturing and trade. Sub-Saharan African countries have poor fertiliser access and usage. Yet, greater fertiliser adoption is a key input to increased food production and therefore a reduction in food insecurity. Access to affordable finance is also a challenge for African agriculture.

Therefore, linking discussions on fertiliser with investments in network industries such as roads and ports is key. It is one thing to have fertilisers available, but moving them to areas of farming is difficult in some countries, and increases the costs for farmers. As part of this, the G20 should drive localised production.

Producing fertiliser on the continent would lessen the negative impact of global price shocks. It would also make it affordable for even the most vulnerable African countries to buy and distribute fertiliser.

Where do you suggest the balance is between more efficient agricultural production and reducing agriculture’s contribution to climate change?

We must use technology to adapt to climate change rather than demonising the use of agrochemicals and seed breeding, which certainly is a rising trend in some areas in South Africa. If we use high yielding seed cultivars, fertilisers and agrochemicals to control diseases, we can then farm a relatively smaller area, and rely on ample output.

But if we reduce these inputs substantially, we rely more on expansion of the area we plant. Tilling more land means hurting the environment. The main focus should be the optimal and safe use of agricultural inputs to improving increase food production. This is key to achieving global food security.

The G20 has a role to play in ensuring that we are moving towards a better world. These agricultural principles we outline above are some of the approaches that could help us move towards a more food secure and better world.

Wandile Sihlobo is the Chief Economist of the Agricultural Business Chamber of South Africa (Agbiz) and a member of the Presidential Economic Advisory Council (PEAC).

– ref. What will it take to make Africa food secure? G20 group points to trade, resilient supply chains and sustainable farming – https://theconversation.com/what-will-it-take-to-make-africa-food-secure-g20-group-points-to-trade-resilient-supply-chains-and-sustainable-farming-267653

November 10, 2025

Harare’s street traders create their own system to survive in the city

Source: The Conversation – Africa – By Elmond Bandauko, Assistant Professor of Human Geography, University of Alberta

The informal sector has become a dominant source of livelihoods for urban residents in African cities. Within this sector, street trading is one of the most visible and vital components of urban economies.

In Zimbabwe’s capital city, too, street traders, selling clothing, snacks, fruits and vegetables, household goods, electronics and many other products, are a dominant feature in the economy. As in most African cities, the majority of Harare’s traders operate without licences, and they are often victims of municipal raids and displacements. Yet, despite this hostile environment, street trading continues to flourish.

How do traders organise themselves in such a difficult setting? Who decides who sells where? And how is order maintained in a space where the state’s control is weak or repressive?

I am an urban geographer whose work focuses on urban informality and governance in African cities. These questions are at the heart of a study that was part of my doctoral research on urban governance and the spatial politics of street traders in Harare. I am especially interested in how the urban poor wield their individual and collective agency to challenge urban exclusion.

Drawing on interviews and focus groups with traders in Harare’s central business district, the research explores the invisible systems of informal governance that regulate access to trading spaces. The study shows that street trading is structured by its own internal rules, norms and power relations.

Informality is not the absence of order. It is a different kind of order, rooted in everyday negotiation, social trust, and the shared struggle to survive in an unequal city.

I concluded that city authorities and others should recognise that these informal governance systems are legitimate, and can even be useful when it comes to formalising activities in the city. Ignoring them could lead to conflict and deeper inequalities.

Systems of organisation

Zimbabwe’s economy as a whole has been unstable over the past four decades. As a result, the informal economy has become very important. The relationship between urban authorities and street traders has always been antagonistic, however. That conflict has been the focus of most of the research on street trading. Harare’s city officials, like those in many other African cities, often treat traders as illegal, criminal, or a threat to “modern” urban order.

My research takes a different view: I shift attention away from state repression to the everyday systems of organisation and control that traders themselves have developed.

I conducted 19 semi-structured interviews and three focus groups with traders, to learn about their individual strategies and shared social mechanisms for keeping order on the streets.

Traders in Harare use informal governance mechanisms – unwritten rules, social norms and personal relationships – to decide who can occupy which space, for how long, and under what conditions. These community-based systems are built on mutual recognition and trust, but also shaped by hierarchy, gender and seniority.

Claiming and defending space

The interviews reveal that the most important rule for maintaining order is consistency. Traders often stay in the same spot for years – sometimes decades – to build customer loyalty and to assert their informal claim.

As one vendor explained:

I stay in the same spot so that people always know where to find me … When everyone sticks to their usual place, it reduces disputes.

This practice, described by another scholar, Asef Bayat, as “quiet encroachment”, involves small, everyday acts of claiming space without formal permission. Over time, these acts become socially recognised by other traders and even by local residents or shopkeepers. If a new vendor tries to take over someone’s space, existing traders usually intervene before conflict escalates.

As one woman put it:

No one can just occupy the space without our permission.

This peer-enforced control system maintains order but also reinforces informal hierarchies.

Leadership and street apprenticeship

Although there are no official leaders, senior traders – those with long experience or strong social influence – often act as custodians of space. They mediate disputes, mentor newcomers and enforce unspoken rules.

Market, Harare.
Shack Dwellers International, Wikimedia Commons, CC BY

New entrants typically undergo an informal “street apprenticeship”, during which they learn how to operate, when to display goods, how to evade municipal police, and whom to approach for protection. Newcomers cannot simply choose a spot and start selling. They must seek the approval of those already established. This process reflects an internalised authority system rooted in social norms rather than written law.

Social networks and inheritance

The study also uncovers how social capital – networks of trust, kinship and friendship – plays a central role in accessing space.

Many traders gain their first selling spot through relatives or friends who are already part of the informal economy. In this way, street trading becomes an intergenerational practice, often “inherited” from parents or grandparents.

One participant explained that her grandmother had traded in the same area for decades, and when she lost her formal job, she joined the family business. Others said they felt morally obliged to reserve a deceased vendor’s spot for their children or relatives.

Competition and exclusion

However, these systems are not equal or fair. Power among traders is unevenly distributed. Long-term vendors and those with strong social connections often dominate lucrative areas, while newcomers (especially young people, women and persons with disabilities) struggle to gain a foothold.

For example, male traders often control spots near busy transport hubs, which are more profitable but also riskier. Women, who are concerned about safety or need to balance caregiving duties, tend to occupy less visible areas. One visually impaired trader said he relied on others to protect his spot, showing how trust and vulnerability shape spatial access.

There are also reports of traders using aggressive tactics to defend their territory. Some long-time vendors admitted to “chasing away” new sellers or even tipping off municipal officers to get competitors arrested. These practices reveal how informal governance can both protect livelihoods and reproduce exclusion.

Everyday politics and quiet power

My study shows that power in Harare’s informal economy is not only top-down, from the state to the traders, but also horizontal, negotiated among the traders themselves.

Those with seniority or strong networks act as gatekeepers, deciding who can sell where. Women traders often face verbal or physical harassment from male counterparts but also develop their own strategies of resistance: confronting aggressors, forming alliances, or using moral arguments about fairness to defend their right to trade. These acts of quiet defiance demonstrate that informal governance is a site of both control and agency.

Beyond stereotypes of chaos

What emerges from this research is a more nuanced picture of Harare’s informal economy. Street traders are not simply victims of a repressive state or chaotic actors in an unregulated market. They are also self-organising agents who build complex systems of order, reciprocity and social regulation in the absence of formal protection.

At the same time, these systems are not utopian. They involve competition, hierarchy and exclusion. Informal governance is both a survival mechanism and a structure of power.

Understanding this duality is crucial for policymakers who wish to design fairer urban policies.

Elmond Bandauko works at the University of Alberta as an Assistant Professor of Human Geography. He received funding from the Social Sciences and Humanities Research Council of Canada (SSHRC), International Development Research Centre (IDRC) and the International Journal of Urban and Research (IJURR) Foundation to conduct this research.

– ref. Harare’s street traders create their own system to survive in the city – https://theconversation.com/harares-street-traders-create-their-own-system-to-survive-in-the-city-268996

November 10, 2025

Africa’s drone wars are growing – but they rarely deliver victory

Source: The Conversation – Africa (2) – By Brendon J. Cannon, Associate Professor, Khalifa University

In the last decade, armed drones have become one of the most visible symbols of modern warfare. Once the preserve of advanced militaries, armed drones are now widely available on the global arms market. Countries such as Turkey, China and Iran are producing lower-cost models and exporting them. In Sudan’s ongoing war, which began in 2023, drones have been used by the two major warring parties to gain ground – but have caused massive civilian casualties in the process.

A drone is essentially a remotely piloted aircraft that can observe, track and sometimes strike targets with missiles or bombs. The promise of armed drones is alluring: a lethal, precise and affordable weapon that can surveil and strike enemies without troops being exposed. But can these drones deliver on their promise in African battlespaces? Brendon J. Cannon shares insights from his study of drone use in Sub-Saharan African conflicts.

What’s driving up the use of drones in sub-Saharan Africa?

Drones offer tactical advantages. They are seen as a solution to pressing internal security problems, from jihadist incursions in the Sahel to armed insurgencies in Ethiopia and civil war in Sudan.

Since 2019, a growing number of African states – among them Niger, Ethiopia, Togo, Sudan and Somalia – have acquired medium-altitude long-endurance (Male) drones. Among these types of drones, Turkey’s Bayraktar TB2 – along with its successors, the TB3 and Kızılelma (Red Apple) – has captured outsized attention. In the case of the Turkish TB2 model, for instance, some sources estimate 40 units have been sold to more than 10 African countries since 2019, but actual figures are not public.

The TB2 is cheap by military standards (roughly US$5 million a unit) and relatively easy to operate. It has been hailed as a “game-changer” for its reliability, cost and ready availability.

The medium-altitude long-eundurance Bayraktar TB2 drone.
Wikimedia Commons, CC BY

It has been combat-tested in Syria, Libya and the Caucasus, a natural border between Europe and Asia.

Its success in destroying tanks, artillery and air defence systems in these conflicts impressed African leaders. As Turkish president Recep Tayyip Erdoğan boasted

Everywhere I go in Africa, everyone talks to me about drones.

What has been the effectiveness of these drones in African conflicts?

Medium-altitude long-endurance drones like the TB2 are entering African conflicts, which are marked by vast geography, difficult terrain and complex insurgencies that frequently span borders.

While drones can deliver lethal force, their ability to shape battlefield outcomes is also contingent on variables like

distance, terrain and weather
the competence of operators
the existence of supporting intelligence, logistics and command systems.

With these variables in mind, my recent research with my colleague, Ash Rossiter, found that drones are unlikely to significantly alter the course of conflicts in much of sub-Saharan Africa, for a couple of reasons.

First, there is a general absence of modern integrated air defences in the region. This is required to deploy drones as lethal precision weapons, particularly in targeting isolated groups.

Second, the success of these drones depends on competent operation, their employment in sufficient numbers, and adequate support infrastructure, such as fuel, communication masts and ground control stations. These are often lacking in remote places where insurgents operate in places like Somalia, Niger and northern Burkina Faso.

What factors limit the lethality of drones?

Where adversaries lack modern, integrated air defences – as is currently common among insurgent and militia forces in much of sub-Saharan Africa – drones can loiter with minimal risk. They can collect actionable intelligence, and conduct precise strikes against vehicles, small groups and supply lines.

This lethality, however, is limited by a number of factors.

Distance: Africa’s size and scale blunt drone range – and therefore efficacy. The TB2’s circa 300km range, for instance, means it worked well in the Caucasus. However, 300km will not get you far in Ethiopia or the Sahel. In Ethiopia, for example, the TB2s had to be repositioned by the government in 2022 from bases near Addis Ababa to Bahir Dar. This was a distance of about 300km, to reach targets in Tigray. This shows how drone bases, security architecture and forward infrastructure, such as communications masts and logistics support closer to conflict areas, are needed. This increases range and, therefore, outcomes.

Terrain and weather: Dust and sandstorms in the Sahel can impair the drones’ visible-light sensors. Sandstorms occur frequently in the region, particularly during the dry season. Dense forest canopies in central Africa can conceal movement from drones. Persistent cloud cover over Ethiopia’s highlands or along the Gulf of Guinea may limit efficacy. Electro-optical and infrared payloads, which provide high-definition and thermal imaging, give drones like the TB2 a 360-degree view. This allows them to operate in diverse weather conditions. But they may need to fly under the weather to see targets in these African terrains. This brings its own risks, as it exposes the drones to potential small-arms fire. This has happened in Sudan, where paramilitary troops reported shooting down army drones in August 2025.

Operator capabilities: Effectively operating a drone requires trained operators, disciplined targeting procedures and dependable maintenance. Failures can be costly. A Burkinabè TB2 crash in 2023 exposed maintenance and operational fragilities, destroying one of five TB2 drones from the Burkinabè arsenal. A Nigerian drone strike in 2023 that was reportedly aimed at terrorists instead killed about 85 civilians. This was after an incorrect grid reference. It underscored how weak operator capabilities can transform precision weapons into harbingers of tragedy.

Fit to conflict: Drones are most useful for hitting supply convoys, eliminating specific targets and targeting loose militant networks. These are missions typical of low-intensity, irregular warfare. They are far less decisive in conflicts against massed troop formations or for holding territory, which has characterised recent wars in Ethiopia and Sudan. These tasks still rely on fighter-bombers or attack aircraft, and ground forces.

What does all this mean for the use of drones in sub-Saharan African conflicts?

First, medium-altitude long-endurance drones can deliver tactical gains but rarely provide a silver bullet.

The initial impression of the TB2 has unfortunately obscured some of its limitations, such as operations across extreme distance, in inclement weather, and the importance of operator proficiency.

Second, in conflicts like Ethiopia and the Sahel, geography and logistics play a critical role. Basing, relay links and forward-deployed maintenance determine a drone strike’s coverage, persistence and power.

Third, a drone’s overall effect depends on trained crews, reliable maintenance, and disciplined targeting and command review. Weakness in any of these can result in tragedy, such as civilian deaths.

Finally, as non-state armed groups increasingly adopt drones and some African states like Rwanda and Kenya begin to field better air defences, the advantage currently held by national governments that own drones will narrow.

Lasting utility, therefore, requires three things.

First, counter-drone defences, which means countries need to develop strategies and acquire sensors, jammers and systems to detect, track and neutralise hostile drones.

Second, better protection of the locations and networks from which drones are controlled so that these are not disrupted, sabotaged or targeted.

Third, sustained investment, not just in drone acquisition but also in maintenance, operator training and basing infrastructure to support continuous flight operations and extend drone reach deeper into battlespaces.

Brendon J. Cannon 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. Africa’s drone wars are growing – but they rarely deliver victory – https://theconversation.com/africas-drone-wars-are-growing-but-they-rarely-deliver-victory-265904

November 10, 2025

South Africa’s flagship telescope at 20: an eye on the sky and on the community

Source: The Conversation – Africa (2) – By Vanessa McBride, Science Director, International Science Council; University of Cape Town

The Southern African Large Telescope (SALT) celebrates 20 years of observing the sky. SALT is the largest optical telescope in the southern hemisphere. It’s been steadily revealing new science knowledge, ranging from the discovery of planets outside our solar system to understanding the unusual physics around black holes. It’s also 20 years of doing science for society.

SALT is where I conducted much of my PhD research. I’d grown up in rural Eastern Cape, marvelling at the diamond night skies. My first fascination for astronomy was sparked when learning about the concept of SALT at a science fest in high school. Years later, I received the first SALT Stobie scholarship for PhD study. It was a dream opportunity to start a multi-year observing campaign.

My research sought to understand how mass moves from one star to another in a gravitationally bound pair. This contributed to the scientific understanding of how these stars evolve in different environments. So it’s with a sense of personal, professional and national pride that I look back on the last two decades of SALT’s achievements.

Africa’s giant eye in the sky

One of SALT’s most significant scientific achievements was based on its ability to respond rapidly to time-critical astronomical events. This allowed SALT to observe the immediate optical glow from a gravitational wave event in 2017, providing a crucial piece of evidence for the type of nuclear processes taking place in the gravitational wave event.

Gravitational waves are ripples in spacetime caused by moving masses, and have only been observable with special detectors since 2015. The plateau on which SALT is built, just outside the town of Sutherland in South Africa’s largest province the Northern Cape, is one of the darkest observing sites in the the world. This makes it an excellent site from which to observe very low brightness objects in the night sky.

In 2022, SALT observed a nearby but faint galaxy, which showed unusually low levels of elements heavier than hydrogen. This unexpected result challenged our understanding of how and when stars begin to form within galaxies. With a repertoire of over 600 scientific publications based on observations from the telescope, SALT has certainly made an impact on our knowledge of the cosmos.

Funded by a consortium of international partners which were led by South Africa’s National Research Foundation, SALT represented an increase of 30x in light gathering capacity compared to the Radcliffe telescope – the previous biggest in South Africa. At concept phase, even astronomers had to be encouraged to think big. The original plans were for a 4 metre class telescope, but it was not audacious enough for a government that wanted to showcase South Africa’s prowess and potential in science.

Engineers and scientists worked with the Hobby-Eberly Telescope in the US to replicate a unique and cost-effective design. Smaller mirror segments were easier and cheaper to manufacture to the required smoothness specifications, and these smaller hexagonal segments could fit together like a honeycomb to create a mirror of 11 metres in diameter. The telescope was designed to point at a fixed angle above the horizon. This meant less warping of the mirror, but a more complicated observing strategy, as astronomers would have to wait for sky to pass over SALT’s pointing direction.

A telescope with heart

SALT was conceived just as South Africa was coming out of the shadow of apartheid. Apartheid – a policy of institutionalised racism – was dismantled in 1994 through South Africa’s first democratic election. In 1996 the new government had written an ambitious white paper setting out a vision for science in a country reborn, where it felt like anything and everything was possible:

Scientific endeavour is not purely utilitarian in its objectives and has important associated cultural and social values. It is also important to maintain a basic competence in ‘flagship’ sciences such as physics and astronomy for cultural reasons. Not to offer them would be to take a negative view of our future – the view that we are a second class nation, chained forever to the treadmill of feeding and clothing ourselves.

SALT has always been more than just a science infrastructure project. It has heart too. Unemployment is a major issue in Sutherland. Fetal alcohol syndrome is also a challenge people battle with in the region, and, through the years of its construction, South Africa was deep into the HIV/AIDS epidemic.

Alongside the investment in engineering and science, was a plan to ensure benefit to previously disadvantaged South Africans, especially the rural community in the Northern Cape. Even today, 20 years after SALT was inaugurated, a fraction of the operation costs that are contributed by all SALT partners, local and international, go into this collateral benefits programme.

The results are a library, skills training centre and a high school mathematics and science teacher in Sutherland. Most recently, the SALT partners and South Africa’s Department of Science, Technology and Innovation, have contributed to a renovated trauma room, for victims of gender-based violence, in the Sutherland police station. In its early years, this programme also trained astronomers through the funding of graduate programmes.

Beyond the horizon

Now, this new generation of South African scientists and engineers is at the helm. For the first time in the 200-year history of the South African Astronomical Observatory, the director is South African. Almost 80% of the staff employed in all roles across SALT, from science and operations to software and mechanical, is South African. These individuals are deeply embedded in, and leading, international science partnerships and research infrastructure projects, and the connection between science and societal development is ingrained in the DNA of these projects and partnerships.

We are often focused on the differences between “us” and “them”, it’s worth remembering the power of science, both as a mechanism for development and as a partnership to unite. This World Science Day for Peace and Development, SALT shows the capabilities science has for both peace, and development.

Vanessa McBride has received funding from the National Research Foundation.

– ref. South Africa’s flagship telescope at 20: an eye on the sky and on the community – https://theconversation.com/south-africas-flagship-telescope-at-20-an-eye-on-the-sky-and-on-the-community-269234

November 10, 2025

Turning motion into medicine: How AI, motion capture and wearables can improve your health

Source: The Conversation – USA – By Azarang Asadi, Data Scientist, Oklahoma State University

The use of motion data is expanding from fitness and rehabilitation to general health. Todor Tsvetkov/E+ via Getty Images

People often take walking for granted. We just move, one step after another, without ever thinking about what it takes to make that happen. Yet every single step is an extraordinary act of coordination, driven by precise timing between spinal cord, brain, nerves, muscles and joints.

Historically, people have used stopwatches, cameras or trained eyes to assess walking and its deficits. However, recent technological advances such as motion capture, wearable sensors and data science methods can record and quantify characteristics of step-by-step movement.

We are researchers who study biomechanics and human performance. We and other researchers are increasingly applying this data to improve human movement. These insights not only help athletes of all stripes push their performance boundaries, but they also support movement recovery for patients through personalized feedback. Ultimately, motion could become another vital sign.

From motion data to performance insights

Researchers around the world combine physiology, biomechanics and data science to decode human movement. This interdisciplinary approach sets the stage for a new era where machine learning algorithms find patterns in human movement data collected by continuous monitoring, yielding insights that improve health.

It’s the same technology that powers your fitness tracker. For example, the inertial measurement unit in the Apple Watch records motion and derives metrics such as step count, stride length and cadence. Wearable sensors, such as inertial measurement units, record thousands of data points every second. The raw data reveals very little about a person’s movement. In fact, the data is so noisy and unstructured that it’s impossible to extract any meaningful insight.

A study participant walks on a treadmill in our lab while a motion sensor attached to the subject’s ankle captures acceleration signals.
Human Performance and Nutrition Research Institute

That is where signal processing comes into play. A signal is simply a sequence of measurements tracked over time. Imagine putting an inertial measurement unit on your ankle. The device constantly tracks the ankle’s movement by measuring signals such as acceleration and rotation. These signals provide an overview of the motion and indicate how the body behaves. However, they often contain unwanted background noise that can blur the real picture.

With mathematical tools, researchers can filter out the noise and isolate the information that truly reflects how the body is performing. It’s like taking a blurry photo and using editing tools to make the picture clear. The process of cleaning and manipulating the signals is known as signal processing.

After processing the signals, researchers use machine learning techniques to transform them into interpretable metrics. Machine learning is a subfield of artificial intelligence that works by finding patterns and relationships in data. In the context of human movement, these tools can identify features of motion that correspond to key performance and health metrics.

For example, our team at the Human Performance and Nutrition Research Institute at Oklahoma State University estimated fitness capacity without requiring exhaustive physical tests or special equipment. Fitness capacity is how efficiently the body can perform physical activity. By combining biomechanics, signal processing and machine learning, we were able to estimate fitness capacity using data from just a few steps of our subjects’ walking.

Beyond fitness, walking data offers even deeper insights. Walking speed is a powerful indicator of longevity, and by tracking it, we could learn about people’s long-term health and life expectancy.

Wearables capture motion signals, and through signal processing and machine learning, the data produces valuable health metrics such as risk of falling.
Human Performance and Nutrition Research Institute

From performance to medicine

The impact of these algorithms extends far beyond tracking performance such as steps and miles walked. They can be applied to support rehabilitation and prevent injuries. Our team is developing a machine learning algorithm to detect when an athlete is at an elevated risk of injury just by analyzing their body movement and detecting subtle changes.

Other scientists have used similar approaches to monitor motor control impairments following a stroke by continuously assessing how a patient’s walking patterns evolve, determining whether motor control is improving, or if the patient is compensating in any way that could lead to future injury.

Similar tools can also be used to inform treatment plans based on each patient’s specific needs, moving us closer to true personalized medicine. In Parkinson’s disease, these methods have been used to diagnose the condition, monitor its severity and detect episodes of walking difficulties to prompt cues to the patients to resume walking.

Others have used these techniques to design and control wearable assistive devices such as exoskeletons that improve mobility for people with physical disabilities by generating power at precisely timed intervals. In addition, researchers have evaluated movement strategies in military service members and found that those with poor biomechanics had a higher risk of injury. Others have used wrist-worn wearables to detect overuse injuries in service members. At their core, these innovations all have one goal: to restore and improve human movement.

Motion as a vital sign

We believe that the future of personalized medicine lies in dynamic monitoring. Every step, jump or squat carries information about how the body functions, performs and recovers. With advances in wearable technology, AI and cloud computing, real-time movement monitoring and biofeedback are likely to become a routine part of everyday life.

Imagine an athlete’s shoe that warns them before an injury occurs, clothing for the elderly that detects and prevents a fall before it occurs, or a smartwatch that detects early signs of stroke based on walking patterns. Combining biomechanics, signal processing and data science turns motion into a vital sign, a real-time reflection of your health and well-being.

Matthew Bird has previously received funding from the Department of Defense. The views expressed in this manuscript are those of the author and do not necessarily reflect the views, opinions, or policies of Oklahoma State University.

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

– ref. Turning motion into medicine: How AI, motion capture and wearables can improve your health – https://theconversation.com/turning-motion-into-medicine-how-ai-motion-capture-and-wearables-can-improve-your-health-266671

November 10, 2025

Why do people have baby teeth and adult teeth?

Source: The Conversation – USA – By Christina Nicholas, Associate Professor of Orthodontics and of Anthropology, University of Illinois Chicago

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

Why do people have two sets of teeth? – Ivy D., age 11, Hyde Park, New York

Teeth help animals bite and chew food. Meat-eating carnivores tend to have sharp teeth to sink into their prey, while herbivores tend to have flatter teeth to grind down their plant-based meals.

Some animals also use their pearly whites for specialized purposes like digging or fighting. Tusks, like you see in elephants, walruses and warthogs, are one special kind of teeth – they grow continuously for as long as the animal is alive.

Over time, no matter what you use them for, teeth wear down. This is good news if you’re a rodent, such as a beaver or a rat. Because their teeth never stop growing, rodents rely on gnawing and chomping to grind their teeth down so they don’t grow so long that they cause problems.

Some animals deal with wear and tear by continuously developing new teeth as their old ones fall out. Sharks and crocodiles, for example, are what scientists call polyphyodont: They can grow nearly infinite sets of teeth.

Some toothy animals just grow new replacement teeth when the old ones fall out.
Marcos del Mazo/LightRocket via Getty Images

Like most mammals, humans are diphyodont: We have two sets of teeth – baby teeth and adult teeth. The technical term for our baby teeth is deciduous teeth because they fall out, the same way deciduous leaves fall off trees in autumn.

We are a dentist who focuses on treating kids and an anthropologist who studies how humans’ teeth and faces grow. We are both passionate about teeth and oral health care, and love thinking and learning about teeth. How did two sets become standard for human beings?

How human teeth develop

Most people are born with no teeth showing in their mouths at all, even though your baby teeth start developing before you’re even born. Baby teeth usually start poking through the gums when you’re between 6 and 8 months old. Sometimes when dentists take X-rays to check for cavities or other problems, they can see adult teeth growing within the gums.

X-ray of a child’s mouth shows two adult teeth growing in the jaw below the visible baby teeth.
David Avenetti

Baby teeth are relatively small because they need to fit in the small faces of babies and little kids. As you grow older and your face gets bigger, you have room in your mouth for more and larger teeth. Teeth have different sizes and shapes, depending on their purpose. Human front teeth are good at biting into things and tearing off a piece of food. Your back teeth are good at chewing foods into smaller bits before you swallow.

Most kids lose their first baby tooth when they’re between 5 and 6 years old, and the process slowly continues until you’re between 10 and 12 years old and all 20 of your original choppers have fallen out.

During that same time, your adult, or permanent, teeth gradually take their spots in your mouth. They’re bigger than your baby teeth and can help you chew more food at once. Eventually you have a set of 28, with the potential of four more wisdom teeth at the very back. Some people just naturally don’t ever grow wisdom teeth, some have wisdom teeth that don’t fit their jaws and need to be removed, and some have big, wide smiles with 32 teeth.

So, getting two sets of teeth means your teeth fit the size of your face as you grow, and helps make sure you can chew food your entire life.

Baby teeth deserve gentle care

You might be thinking that if baby teeth are just going to fall out, they can’t be that important. But that’s not true.

If you were a shark, every time you got a bunch of cavities or chipped a tooth, you’d just grow a new one and keep on chewing. But unlike sharks or crocodiles or even manatees, we humans only get two sets of teeth. By taking care of your baby teeth, you can keep them healthy and make sure they stay right where they belong until they’re ready to fall out.

If you don’t take care of your baby teeth, they can wind up with lots of cavities. If the cavities get too large or teeth become infected, they may need to be removed by the dentist. Not only is this process not fun, but taking out baby teeth too early can create problems for your adult teeth.

You can wind up with not enough space for your adult teeth to come in – that is, what dentists call “erupt” – into the right spots. This issue happens in part because the other teeth around where the baby tooth was will shift and may move into the space where your adult teeth are supposed to come in. Teeth can get stuck in the jaw and not erupt, or your teeth can be crowded in your mouth. If there is a mismatch between the size of your teeth and the size of your jaws, an orthodontist might attach braces to your teeth to reposition them so they all fit.

What is the future of teeth?

Because people can live long lives, 70 or 80 years or more, many outlive their teeth even if they do their best to take care of them. While there are lots of options for artificial teeth – like removable dentures or even dental implants, which are fake teeth that are screwed into your jaws – it’s not quite the same as having natural teeth.

Taking good care of your teeth decreases the chance you’ll need an artificial replacement someday.
Andriy Onufriyenko/Moment via Getty Images

If you break a bone, it heals because you can grow new bone to patch up the part that broke. Scientists call this process fracture healing. Human teeth aren’t bone and, unfortunately, do not heal themselves. Unlike your bones, which are mostly composed of a structural protein your body makes called collagen, your teeth are primarily made up of minerals such as calcium-rich hydroxyapatite. In some ways, teeth are closer to being like hard stones than living bones.

Regenerative dentistry is the study of how teeth grow and develop, with the goal of ultimately designing new ways to repair and replace our teeth. Scientists are working hard to figure out ways to grow new teeth or help existing teeth regenerate. They’re learning about the environment and materials needed to grow new teeth.

For now, the best thing you can do is take good care of the teeth you have and keep the gums and bones that support them healthy. Brush your teeth twice a day with toothpaste that contains fluoride, and floss once a day. Try to limit sugary, sticky foods and drinks – a good diet keeps your whole body healthy, not just your teeth. See a dentist regularly, and protect your teeth from injury.

Being kind to your teeth now can help your future self have a beautiful, healthy smile.

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

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

David Avenetti receives funding from the National Institutes of Health (National Institute of Dental and Craniofacial Research) and the Health Resources and Services Administration.

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

– ref. Why do people have baby teeth and adult teeth? – https://theconversation.com/why-do-people-have-baby-teeth-and-adult-teeth-256198

November 10, 2025

What America’s divided and tumultuous politics of the late-19th century can teach us

Source: The Conversation – USA – By Robert A. Strong, Senior Fellow, Miller Center, University of Virginia

Can today’s divided America learn something from the divisions of the past? zimmytws, iStock/Getty Images Plus

People trying to understand politics in the United States today often turn to history for precedents and perspective. Are our current divisions like the ones that preceded the American Revolution or the Civil War? Did the dramatic events of the 1960s generate the same kind of social and political forces seen today? Are there lessons from the past that show us how eras of intense political turmoil eventually subside?

As a scholar of American politics and the presidency, I believe one American historical period is especially worth revisiting in this turbulent moment in the U.S.: the 20 tumultuous years between the presidencies of Ulysses S. Grant and William McKinley in the second half of the 19th century.

The two decades between 1876 and 1896 are usually remembered as a time when the cities in the East grew rich and the West was wild – a “Gilded Age” in New York City and gunslingers on the frontier.

It was also a time when Americans struggled with immigration issues, racial injustice, tariff levels, technological change, economic volatility and political violence.

There was even a president, Grover Cleveland, who served two nonconsecutive terms in the White House – the only time that happened before Donald Trump.

In the elections between Grant and McKinley, the nation was closely divided. No president in those years – not Rutherford Hayes, James Garfield, Chester Arthur, Cleveland or Benjamin Harrison – served for two consecutive terms. No presidential candidate won more than 50% of the popular vote, except the Democrat Samuel Tilden. And Tilden, after winning 50.1% of the ballots cast in 1876, lost in the Electoral College. That happened again in 1888 when Cleveland, the first time he was seeking a second term, won the popular vote but failed in the Electoral College.

The narrow victories that characterized presidential politics in the 1870s and 1880s were matched by constant shifts on Capitol Hill. In the 20 years between Grant and McKinley, there were only six years of unified government, when one political party controlled the White House, the Senate and the House of Representatives. In the remaining 14 years, presidents encountered opposition in Congress.

The U.S. has the same kind of divided politics today.

Heating up partisanship and raising stakes

President Bill Clinton had two years of unified government; President George W. Bush had less than that. Barack Obama, Donald Trump in his first term and Joe Biden all came into office with party majorities in the House and Senate, and then, like Clinton, their parties lost the House two years later.

Divided politics, with close elections and neither party in power for very long, make partisanship more intense, campaigns harder fought and the stakes sky high whenever voters go to the polls. That’s part of what produced instability in the second half of the 19th century and part of what produces it today.

Divided government is, of course, one of the most powerful “checks” in the constitutional system of checks and balances. Intense competition between political parties can prevent the national government from making rash decisions and serious mistakes. It can sometimes generate compromise.

Residents and protesters clash with federal agents on Chicago’s East Side on Oct. 14, 2025.
Joshua Lott/The Washington Post via Getty Images

But there’s a cost. Political division can also allow critical problems to fester for far too long. The dramatic changes brought on by the Industrial Revolution after the Civil War were not seriously addressed in federal legislation until the Progressive Era early in the 20th century.

In the second half of the 19th century, Congress raised or lowered tariffs – depending on which party controlled the White House and Capitol Hill. The nation debated immigration but only once passed meaningful legislation, the Chinese Exclusion Act of 1882. A long list of issues connected to railroads, banks, currency, civil service, corruption and the implementation of the post-Civil War constitutional amendments were ignored or only partially addressed.

When major legislation was passed in 1883 to create a merit-based civil service – reforming the spoils system of political appointments – it passed because Garfield’s 1881 assassination by a disgruntled federal job seeker temporarily pushed the issue to the top of the national agenda.

Immigration, fake news and riots

Political violence accompanied the period of closely divided national elections in the 1870s and 1880s.

In the 1880 presidential campaign, both candidates – the Republican, Garfield, and the Democrat, Winfield Hancock – called for restrictions on Chinese immigration to the United States. Neither supported the complete ban that many Westerners wanted.

But just before Americans went to the polls, newspapers across the country printed a letter, allegedly written and signed by Garfield, that endorsed an open border to Chinese immigrants. Before anyone could learn that the letter was a fake, there was public uproar. In Denver, an angry mob burned down all the homes in Chinese neighborhoods.

There were more incidents of political violence: anti-Chinese riots in Los Angeles in 1871, in San Francisco in 1877 and in Seattle in 1886.

Throughout the 1880s, anti-immigrant nativists targeted immigrants from Italy and sometimes vandalized Catholic churches.

Political violence in the South successfully suppressed Black voting rights and reestablished white control of state and local politics.

Political violence accompanied the period of closely divided national elections in the 1870s and 1880s, including the assassination of President James Garfield in 1881.
Glasshouse Vintage/Universal History Archive/Universal Images Group via Getty Images

Realignment

Political division in the second half of the 19th century produced more problems than solutions. How and when did it end, or become less intense?

The simple answer is what political scientists call a “realignment,” a major shift in national electoral patterns.

In 1893, the first year of Cleveland’s second term, the nation suffered a financial crisis followed by a severe economic depression. As a result, McKinley was able to win solid victories in 1896 and 1900 and build a Republican coalition that dominated presidential politics until the election in 1932 of Democrat Franklin Roosevelt.

It’s not hard to imagine how an economic disaster, or a crisis of some kind, could shake the country out of a period of closely divided politics. But that’s a painful way of building a higher level of national unity.

Can it happen when large numbers of voters get thoroughly frustrated by languishing issues, swings back and forth in Washington, nasty elections and rising political violence?

Perhaps.

But either way – responding to crisis or finding a public change of heart – is a reminder that voters are the ultimate arbiters in a functioning democracy. Today, as in late-19th-century America, elections make a difference. They can mark continued division or they can take the nation in a new, and perhaps more unified, direction.

Robert A. Strong 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. What America’s divided and tumultuous politics of the late-19th century can teach us – https://theconversation.com/what-americas-divided-and-tumultuous-politics-of-the-late-19th-century-can-teach-us-267292