Johansen.se

The ratios of strontium isotopes in fossil shark teeth can be used to better understand how coastal environments evolved in ancient times, according to our newly published work.

As paleontologists with the Florida Museum of Natural History, we’re interested in understanding ancient Florida environments.

Our study was one of the first to date Florida coastal deposits using fossil shark teeth and a technique that looks at variations in ocean strontium. Strontium is a chemical element that occurs naturally in rock, soil and water.

By analyzing the strontium levels in fossilized shark teeth, scientists can determine the age of the fossil and gain new insights into the history of the area where the teeth were found.
FLMNH/Jeff Gage

Ocean strontium values change over time, which makes measuring the levels of the chemical element a unique global system for determining the age of similar coastal sedimentary rock deposits worldwide.

Changes in strontium isotope ratios have multiple causes. Land erosion deposits strontium into oceans, while carbonate-producing marine life produce and release strontium when building their skeletons. Strontium is also released by deep-sea vents.

Geochemist Donald DePaolo and geologist B. Lynn Ingram discovered variations in ocean strontium by examining strontium isotopes ratios in marine sediments, including fossils. The levels of strontium isotopes in marine sediments provide a “time stamp” that correlates to the strontium value of the seawater at that time.

That data allowed scientists to map out ratios of strontium isotopes in seawater over time. This global strontium seawater curve correlates to the geologic timescale. Scientists use the curve to reconstruct past ocean chemistry and climate conditions, as well as the age of mollusks and other shell-producing marine fossils.

Why it matters

Properly dating ancient sites is key to understanding how Earth and its living creatures evolved over time.

But historically, strontium dating, while reliable, had limitations.

For example, it works best in fully marine environments and is challenging to use in fossil sites along coastlines. That’s because the strontium values might be influenced by land sediments and freshwater rivers.

Additionally, material used for strontium dating must not have undergone considerable physical and chemical change during fossilization, the preservation of once living things from the past. Any major chemical alteration to the fossil can affect the strontium value and give an inaccurate date.

Our study shows that fossil shark teeth are more resistant to these types of changes due to their outer enamel-like surface.

Remarkably, fossil shark teeth are also incredibly abundant. Sharks ruled the earth’s oceans for 400 million years, and every individual grows and sheds thousands of teeth in their lifetime.

How we did our work

Florida fossil sites are unique in that they possess some of the richest fossil sediments for important times in geologic history. These sites can help us understand changing climates, vegetation and sea levels over time.

The Florida Museum of Natural History has a collection of over 115,000 shark tooth specimens from Florida alone.

To do our study, we selected shark tooth specimens from two significant Neogene-period fossil sites in Florida. The Neogene, from 2.6 to 23.5 million years ago, was a time of immense change in biodiversity because of changing climates.

We analyzed the strontium present in powdered samples collected by shaving a thin layer from the surfaces of the teeth. The age of the teeth helped to clarify the age of the fossil sites where they were collected. This data enabled us to calibrate and differentiate the ages of our two sites, Montbrook and Palmetto Fauna Bone Valley, by about 600,000 years.

Stephanie Killingsworth, left, and Bruce MacFadden, right, collect fossilized specimens at the Montbrook fossil site in Levy County, Fla. Image Credit:
FLMNH/Jeff Gage

Before our study, scientists could estimate the age of the sites based only on mammal fossils. The sites were thought to be the same age. Our work provides a more precise date.

During the Great American Biotic Interchange, animals from the north (depicted in green) migrated south, while animals from the south (depicted in blue) migrated north.
Wikipedia

These ages offer new insights into what happened in the southeastern region of North America, some 5 million to 6 million years ago. Our revised age calibrations coincide with global events, including major sea-level fluctuations and the Great American Biotic Interchange – the migration of land mammals between North and South America after the formation of the Isthmus of Panama 4 million to 5 million years ago.

For example, because certain species of ground sloths are not found at the Montbrook site (5.85 million years old) but are found at the Palmetto Fauna Bone Valley site (5.22 million years old), it suggests the immigration of ground sloths into North America occurred between these two dates.

The Research Brief is a short take on interesting academic work. Läs mer…

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.

Where does black fall on the color spectrum? – Utsav, age 17, Navi Mumbai, Maharashtra, India

People love the rainbow of ROYGBIV colors: red, orange, yellow, green, blue, indigo and violet. Human eyes perceive visible light as this array of colors.

You may notice that some colors you can perceive aren’t part of the classic rainbow, though. Where is black, for example?

I’m an associate professor of color science, a field that combines physics and perception. Color scientists are interested in learning more about human vision and applying that knowledge to make color systems – such as in cameras, screens or lighting systems – work better.

To understand where black falls on the color spectrum, first consider what light actually is.

Light is radiation visible to the human eye

Light is energy called electromagnetic radiation. It’s made up of a stream of energy particles called photons.

Each photon has its own energy level. There are two characteristics you can use to describe a photon. Its frequency is how fast it vibrates back and forth – or oscillates – as it travels. And its wavelength is the distance between those oscillations in space.

Light is made up of photons traveling as waves through space.
DrSciComm via Wikimedia Commons, CC BY

As photons with wavelengths within a range of about 400–700 nanometers stream into your eyes, your brain perceives them as light. Scientists call these photons visible radiation. You perceive photons with different wavelengths as different colors.

Photons outside that range of wavelengths are invisible to human eyes. Shorter wavelength energy includes ultraviolet, X-ray and gamma radiation, while longer wavelength energy includes infrared and radio waves.

The human eye can perceive only a small range of wavelengths of radiation.
Ali Damouh/Science Photo Library via Getty Images

Shades and intensities

Color perception is also affected by the quantity of photons – what physicists call the power – at different visible wavelengths. More photons means more powerful light, which looks brighter. A very vivid color consists mostly of photons of similar wavelength. For example, a pure red may consist of photons that all share the same wavelength near 620 nanometers.

A stream of photons with a wider range of wavelengths will appear as a paler, less saturated color. White light, such as natural daylight, consists of photons with wavelengths spread fairly evenly across a wide range of the visible spectrum. LEDs and other electric light sources are not quite as uniform across the spectrum, but they still appear white or achromatic, meaning without color.

Mixtures of wavelengths combine and appear as new colors. The human visual system interprets pure red light and pure green light combined as yellow. Add in pure blue, and this mix of radiation appears white. Scientists and engineers take advantage of this quality in display devices, which are able to create a huge range of perceived colors by mixing the primary colors red, green and blue.

Black on the color spectrum

While there’s no black in a rainbow, photons anywhere in the electromagnetic spectrum can be seen as black. Or in some cases, they can’t be seen at all!

Radiation within the visible spectrum can appear black if it is low in power – more specifically, lower in power than its surroundings.

Additionally, radiation outside the visible range of wavelengths appears black to our eyes. For example, infrared radiation appears black because it is invisible to humans.

Perception is subjective

Our eyes detect the wavelength and power of the light, but our brains interpret it. So color perception always depends on the context.

People are good at adapting to a wide range of light levels, from sunlight to starlight. So our perception of color and brightness depends on what’s around and what we’ve been looking at recently. If you step from outdoor daylight into a dark theater, at first you probably perceive the whole environment as black, and you may even have trouble finding your way.

However, your visual system immediately begins to adapt to the low light level. Soon, visual details begin to emerge. What appeared black now has different levels of lightness and color.

Color perception depends on the surrounding environment.
Michael J. Murdoch

Consider the optical illusion that consists of a light rectangle next to a dark rectangle. Each rectangle contains a circle. The circles appear to be different shades but in fact are identical. Against the light background, the circle is dark enough to appear black. Surrounded by the black background, it becomes clear that the circle is merely dark gray. Even when you know the circles are the same, it’s hard to believe because the effect of the surrounding background is so strong.

In a smooth gradient from gray to black, where does black begin?
Michael J. Murdoch

You might be asking yourself, how dark must a color be to appear black? Another way to ask the question is, how low in power must the physical light be in order to look black?

For a visual answer, look at a gradient from dark gray to black. Where in the gradient is the boundary, or threshold, at which you call it black? What if you dim your display or view the screen in a much brighter or much darker environment? Probably the best answer for how dark it must be is, “It depends.”

Color perception is a fascinating topic, and we color scientists are continuing to uncover details of how the human visual system works while also applying our knowledge to many other useful things, including dyes, cameras, printers, LED lighting systems and AR/VR displays.

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. Läs mer…

Your genes play a major role in determining your height, hair and eye color, and skin tone, but they don’t tell the entire story of who you are. Your environment is incredibly important in shaping your personality, your likes and dislikes, and your health. In fact, your diet, social interactions, exposure to pollution, physical activity and education often exceed the influence of genetics on many of the features that define you.

Figuring out how your genes and environment increase your likelihood of developing asthma, heart disease, cancer, dementia and other conditions can have life-changing consequences. The field of genomics has made it relatively straightforward to test both in the hospital and at home for a wide range of genetic variations linked to disease risk.

And in recent years, science has been making progress on tracking down the environmental culprits that drive risk for several diseases – and on identifying ways to optimize treatments based on your personal environmental exposures.

Prescribing the most effective treatment from the get-go can reduce harmful drug reactions.
Willie B. Thomas/DigitalVision via Getty Images

My work as a pharmacologist and toxicologist has led me to the emerging science of exposomics – the study of all of the physical, chemical, biological and social factors that affect your biology. While your genome comprises all of the genes that encode your biology, your exposome is a concept that comprises all your environmental exposures. Like how researchers use DNA sequencers to study genomics, scientists in exposomics use chemistry and high-tech sensors to measure the effects of thousands of environmental factors on health.

Medications don’t always work

For many people, standard drug therapies to treat certain conditions simply don’t work. Controlling blood pressure often requires months of trial and error. It can take months or even years to identify an adequate treatment plan for depression.

Adverse events caused by medications account for more than 1 million visits to emergency departments each year in the U.S. What drives these differences in drug effects between patients? Is it their genes? Are they not taking their medication as prescribed due to side effects? Or something else?

As it turns out, your environment can have a major effect on how well specific treatments work for you. Think about the warning labels advising you not to drink grapefruit juice while taking a specific drug, for example. This is because a natural chemical in grapefruit inhibits the enzymes that break down those medications. Some common statins used to control high cholesterol can build up to toxic levels because the chemical in grapefruit juice blocks its normal processing.

Grapefruit isn’t the only environmental factor affecting how you respond to your medications. Over 8,600 chemicals are used in commerce in the U.S., and you are exposed to thousands of these chemicals on a daily basis. It is more likely than not that many of these chemicals can interact with the drugs you take.

Your exposome encompasses a wide range of factors.
Nathalie Ruaux/Wikimedia Commons, CC BY-SA

Some of the chemicals we use to keep fleas and ticks off pets can actually increase the levels of the same enzyme blocked by grapefruit juice, meaning a statin may be broken down so fast that it doesn’t control elevated cholesterol.

Byproducts from the combustion of organic matter, such as engine exhaust and burning wood, can also interfere with drug-metabolizing enzymes. Some of these chemicals, called polyaromatic hydrocarbons, can inactivate medications used to treat asthma. The environmental factor triggering your asthma could prevent the drugs used to treat it from working.

A chemical solution?

Advances in chemistry are helping researchers figure out what chemicals are getting in the way of treatment.

Your hospital laboratory can already measure dozens of molecules in your blood. Measuring your salt levels can tell doctors how your kidneys are working, cholesterol levels indicate your risk of heart disease, and specific enzymes reveal your liver’s health. These common tests are routine and useful for nearly every patient.

There are many additional tests that can help determine how a specific condition is progressing or responding to therapy. Hemoglobin A1c levels help determine how well glucose levels are being controlled in those with prediabetes or diabetes. And thousands of other human diseases have their own corresponding biomarkers.

In research laboratories, scientists can detect the presence of thousands of molecules at once using instruments called mass spectrometers. Each chemical in a sample has a unique mass, and these devices measure these masses for scientists to categorize. Thus, scientists can identify all of the pesticides, plasticizers, plastics, pollution and other chemicals present in a given sample. They can also measure your own internal biology, such as the compounds involved in processing the food you eat and the hormones influencing how you behave.

A sample mass spectrometry reading of lab air. Each peak indicates the presence of a particular compound.
Philipp Sulzer/Wikimedia Commons

Moreover, mass spectrometers can measure drug metabolites. When you take a drug, it is typically broken down or metabolized to several different compounds. Some of these compounds contribute to the drug’s effects, while others are inactive. Analyzing what metabolites are present in your body provides information about how you process drugs and whether the drugs you’re taking will interact with each other.

Taking all these factors together, scientists can study how your environment may be interfering with the effectiveness of your medications.

A better prescription – for you

Together with dozens of scientists across many institutions, my colleagues and I are developing methods to measure all of the chemicals in your body. The project, dubbed IndiPHARM – short for individualized pharmacology – is designing tools to measure a wide range of drugs, drug metabolites and environmental chemicals at the same time.

By combining environmental data with genetic information, we hope to improve how drugs work in people by figuring out whether chemicals in their environment or diet are altering how they process a given drug. This includes whether the administered drugs are at therapeutic levels, how the drugs and chemicals are interacting with each other, and determining whether other variables are affecting intended drug effects. This could lead to changing the amount of drug prescribed, switching to a different medication or even redesigning the medicines themselves.

Our team is starting with identifying the environmental and biological factors associated with metabolic diseases, including obesity and diabetes, along with common co-occurring conditions such as hypertension, high cholesterol and depression. For example, there are significant differences in how well people respond to anti-obesity or anti-diabetes drugs, and we hope to figure out why that is so all patients can benefit through tailored treatment.

Getting the right drug to the right person at the right time requires a better understanding of the environmental factors that influence how they work. We envision a future where a doctor can use your genetic and environmental history to figure out the best drug treatment that would work for you from the start, reducing the need for trial and error. Läs mer…

Setting our boundaries can sometimes be tough. Maybe you’re living with someone who’s always in your space. Or you’ve got that friend who feels a little too comfortable trauma-dumping on you. Maybe you feel your spouse isn’t respecting your choices.

Whatever the reason, telling others how you feel isn’t always easy. And it can be difficult to figure out where to draw your lines and how to communicate them to others.

There’s also a lot of misunderstanding about what boundaries are and what they aren’t. The prevalence of “therapy-speak” can make figuring that out even harder.

Setting boundaries can often seem complicated and feel uncomfortable. That’s because it can take a lot of courage to stick up for yourself. It also takes a lot of emotional regulation and self-awareness.

However, setting boundaries doesn’t have to be a daunting prospect. Taking time to figure out how to communicate them effectively can lead to healthier relationships with the people in your life.

Ready to make a change? The Quarter Life Glow-up is a new, six-week newsletter course from The Conversation’s UK and Canada editions.

Every week, we’ll bring you research-backed advice and tools to help improve your relationships, your career, your free time and your mental health – no supplements or skincare required. Sign up here to start your glow-up at any time.

Setting healthy boundaries

Think of boundaries as promises you make to yourself about how you will respond to others when their actions or words conflict with your self-worth, communication style and relationship expectations. Things that influence our beliefs towards boundaries can include our cultural, religious and political identities.

Boundaries are about what you do when something triggers an emotional response from you, and how you communicate to others what you are feeling. Boundaries are not about telling others what to do or how to feel.

People in different places approach them in different ways. American authors like Brené Brown see boundaries as a way of loving ourselves by saying no, even if that means we let someone else down.

Looking at cultures around the world can also help us learn more about the intricate relationship between boundaries, communication style and relationship expectations. For example, in Iran the term gheirat refers to a moral-emotional experience. It is a concept referring to an experience when there is a violation involving people, such as romantic partners, family dynamics and politics.

A healthy boundary can be invitational, meaning you are inviting others to participate in the problem-solving process. In relationships we have to balance our feelings, their feelings and what is needed for the relationship to blossom. This tricky balance means inviting others in, while indicating what is needed for you to safely participate.

For example saying “let’s finish this conversation when neither of us is raising our voices” is a healthy way of setting a boundary compared to “leave me alone right now” or “don’t speak to me like that.”

Telling someone not to speak to you during a hard conversation can sound dismissive of their feelings, especially if they’re feeling unheard. The boundary is not about the conversation ending, it’s about what is needed for the conversation to continue in a respectful way.

You don’t always owe others your time to communicate and explain what you need. Sometimes, it’s about walking away from a situation that you know isn’t serving you.
(Shutterstock)

Communication is key

Healthy boundaries can be a way to mutually emotionally regulate. For example, saying “it makes me uncomfortable when you tell your friends personal details about our relationship” is offering others two opportunities. The first, awareness of how their actions are making you feel. And second, the opportunity to problem-solve with you.

Most people will respond by explaining why they are doing what they are doing. With that information, you can decide how you want to respond. Maybe they’re choosing to disclose information to their friends because they rely on external processing to help make decisions. Or maybe they’re looking for external validation. You get to choose how to respond now that you have their rationale.

As a therapist, I often tell clients you have options when it comes to setting and maintaining boundaries. The next time you have to set a boundary, think of the following tips.

Do:

Express how you’re feeling in response to someone’s actions or inaction.
Identify your priorities and know your limits. Provide an opportunity for repair.
If someone tells you why they did what they did, remind them it’s important for you they recognize how you’re feeling versus rationalizing their behaviour.

Don’t:

Tell someone how to act or feel.
Expect others to know what you need or what you’re thinking.
Rely on others to uphold your boundaries.

You don’t always owe others your time to communicate and explain what you need. Sometimes, it’s about walking away from a situation that you know isn’t serving you. Based on how you observe people living their life, how they talk about social or political issues, conduct themselves when you express your feelings, you can choose not to give people access to your life.

Sometimes walking away is about preserving your self-worth, especially after you’ve tried communicating and problem solving. This is where boundaries become hard to maintain, because we have to determine whether someone’s actions are enough to protect ourselves and uphold our self worth.

However you choose to set your boundaries, communicating them honestly and calmly is key to getting others to understand and respect them. Läs mer…

SimCity 3000, the predecessor to The Sims, played a pivotal part in my childhood, growing up in Hyderabad, India. Its recreation of the western, urban world helped me understand how cities were planned, designed and financed – and how they provided people with key services like transportation, health and education while preparing for accidents and other hazards.

As an eight-year-old trying to figure out my place in the world, that game offered me a way to make meaning of the chaos that can be life. So, when The Sims launched in 2000 – enabling me to live inside a virtual city, rather than simply build one – I had to get my hands on a copy.

Twenty-five years later, I write this piece in a drastically different gaming landscape, where games offer high visual fidelity and ever-increasing frame rates for ultra-smooth game play. But despite all these technological innovations and the pursuit of photo-realism, the popularity of The Sims’ game designer Will Wright’s satire on American consumer culture endures.

Sul Sul! This article is part of a mini series from The Conversation marking 25 years of The Sims franchise.

The franchise’s four Sims games had sold over 200 million copies before the latest instalment, The Sims 4, became free to play in 2022. Players now spend their money on extras within the game. Over 85 million people played The Sims worldwide in 2024.

At a time when the success of a modern video game is measured in metrics like “cumulative engagement time” (number of players playing at the same time), acquisition of new players and “intensity of engagement” (number of hours spent by a player), now-over-a-decade-old The Sims 4 continues to excel with its mastery of the live-service format.

The trailer for the first Sims game.

Live-service describes the form modern digital games embrace when they transition from conventional products into “services” – a shift made possible because games today can be regularly updated, fixed and expanded upon by their makers remotely. They can acquire new levels and in-game features in a similar way to how streaming platforms like Netflix drop new episodes of your favourite show.

Players don’t buy a live-service game, they sign up for the journey.

Expanding player horizons

In each incarnation of The Sims, players have been able to access new ways to perform roles and tasks that mimic everyday life, in the form of expansions and content packs.

The original title, The Sims (2000), had seven expansion packs and two content packs. I distinctly remember brewing potions in the chemistry lab and rubbing a magic lamp to conjure a genie in the first expansion, Livin’ Large; the new holiday island that was built for The Sims: Vacation; and leaving my Sim’s home to visit downtown areas as part of Hot Date.

The trailer for The Sims Hot Date expansion pack.

But for The Sims 4 (2014), the developers went all in. This game – and its subsequent expansions – represents a digital supermarket of lifestyles, sub-cultures, activities and stardom. For example, 2018’s Get Famous pack not only introduced Del Sol Valley – a region that resembled Los Angeles and the Hollywood Hills – but also introduced the “reputation” mechanism for players.

The Discover University expansion (2019) allowed players to take their Sims to school in a new region called Britechester – after this update, the game integrated Sims’ careers and education, and in many ways changed the rules of the game. And the Eco Lifestyle expansion pack (2020) is memorable because the game engaged with ideas of sustainable living for the first time.

Genre, fantasy and reality

From content packs featuring a digital recreation of singer Katy Perry in The Sims 3 to collaborations with streamers, content creators and fashion houses, The Sims has remained relevant by consistently blurring the lines between genre, reality and fantasy.

Hot Date was a popular early Sims expansion pack.

Today, video game makers the world over try to master formats like free-to-play games where players pay for cosmetic items, customisations and added content, or expansions offering downloadable content. The Sims set the standard for most of them.

Over the past 25 years, this franchise has had several life simulation competitors in the form of Second Life, Facebook’s once popular Farmville, virtual reality experiences like Half-Life: Alyx and, during the pandemic when we worked, learnt and played online, initiatives like the Metaverse.

However, today only The Sims endures. The game’s developers continue to give its players what they want, while also getting them to engage with difficult ideas like sustainability, the question of life and death, and even gentrification (For Rent expansion pack, anyone?).

Few games let players critique life so closely. For game researchers like me, this begs the question: do people play life simulation games like The Sims in order to build alternative lives, relive their own – or create something entirely new?

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

To disagree is an inescapable part of being human. We simply are not all the same. But whereas a small disagreement may remain amiable, particularly over text or online where we can edit our responses, a face-to-face row over a sensitive topic can develop into a more antagonistic form of argument.

You may have experienced this over the recent festive season, when many of us spend more time in close contact with our relatives than usual. This can sometimes bring simmering tensions to the surface.

An argument can start over a lot of things, from politics to each other’s behaviour – something anyone who spends much time on social media will be familiar with. But the stronger the view, the more intense and complex an argument can become.

So, what can you do to avoid a minor argument becoming a major row – whether online or face-to-face? As an expert in social interactions, I think paying attention to what someone says – and how they say it – is crucial, along with learning how to avoid responding in ways that might blow up in your face.

Remember, disagreements are a normal part of life and relationships. But here are three key tips for how to avoid them escalating into something more serious.

Ready to make a change? The Quarter Life Glow-up is a new, six-week newsletter course from The Conversation’s UK and Canada editions.

Every week, we’ll bring you research-backed advice and tools to help improve your relationships, your career, your free time and your mental health – no supplements or skincare required. Sign up here to start your glow-up at any time.

1. Manage escalation

If you disagree with someone, stay in the conversation in a productive way by avoiding using direct insults. Also, take care to avoid actions that may put the other person on the back foot, such as accusing, complaining or mocking them.

We tend to put a lot of emphasis on the content of an argument, and also on our assumptions about what the other person “really thinks”. What is the argument about? Is it just a misunderstanding – or is it a matter of personality, where one party is biased or has some ulterior motive?

The rise of social media has created an age of endless conflict.
pathdoc / Shutterstock

We care very much whether the person actually believes what they are saying. Research suggests we often resent people playing “devil’s advocate” outside of certain settings.

But you cannot truly know someone’s intentions, so it’s a good idea to avoid thinking the worst about the person you are arguing with. Otherwise, you might unfairly talk to them as if they’re being manipulative, unfair, damaging or thoughtless.

2. Be open-minded

Sometimes, what someone has said may sound (and feel) pretty awful. When this happens, keep two things in mind.

First, nothing we say has just one meaning. There are often multiple interpretations, and you cannot always trust the first one that leaps to mind when you’re in the heat of the moment.

During an argument, it’s worth slowing down and thinking through all possible interpretations. Consider asking for a moment to think, or getting a cup of tea to distract both of you from an escalation.

Second, if what the person is saying still sounds negative no matter how charitable you try to be, ask them to explain more. This may not be easy to do, but people will often reveal what they meant if they have to elaborate. And helping them feel as if they are being carefully listened to might defuse a possible escalation.

3. Stay on track

There is another side to this coin: choosing carefully what you say, and keeping in mind how you will come across. Anyone can get caught up in an argument and say something they regret, including you.

Something to balance carefully is “going meta” – pausing to talk about the argument you’re having and the way you’re having it. This can be productive if, for instance, you ask to keep the conversation focused on something specific. However, it can easily come across as an implicit criticism of the other person.

If you do choose to discuss the quarrel you’re having, you may have to include an apology or speak in a quieter tone to keep the other person from thinking you are going to accuse them of arguing “wrongly” in some way. It’s challenging, so don’t feel bad if you don’t get it right the first time you try this technique.

Anyone can get caught up in an argument, including you.
fizkes / Shutterstock

Do we have the same values?

People don’t just argue for the sake of arguing. One of the main reasons for engaging in an argument is to position ourselves in relation to other people. Are we on the same side, and do we have the same values?

Arguments are also tied to identity. The most contentious arguments generate strong feelings. We’re aware that we might be judged for our opinions, and others will assume that we might judge them in return.

Mutual judgment can easily escalate not just during a disagreement but in the relationship as a whole, causing a temporary falling-out or even loss of friendship. People who want to avoid this often assume the answer is to simply put their feelings aside and “focus on facts”.

But denying an emotional response might feel like denying one’s commitment to a valued cause. Recognising that someone feels this way is an important step to knowing what you might be able to change their mind about – and what is best left alone, at least for now. Läs mer…

Hanging the washing out to dry in the garden has been a rare sight these last few months, with winter storms bringing freezing temperatures and 100mph gusts of wind. But does the way we dry our clothes indoors actually matter?

Drying wet clothing on racks in poorly ventilated spaces could increase the amount of mould growing in your home, which is associated with poor health and, in some cases, even death.

When mould grows in your home, it can form black or green coloured patches on the walls, and usually creates an unpleasant musty smell. It shouldn’t be ignored, because being exposed to mould over long periods of time can have serious health implications.

Mould is a broad term for a group of fungi that produce tiny particles called spores. Fungi produce spores when conditions are right for their growth, which can include cooler temperatures and high humidity. This is why you’re more likely to find mould growing on bathroom ceilings or damp walls, where there is more water for fungal spores to settle and grow.

There are many different species of mould. The most common ones to cause problems in damp homes are penicillium and aspergillus. It’s estimated that we breathe in small numbers of spores from these fungi on a daily basis.

Luckily, our immune system is very good at spotting and killing fungal spores, which limits the number of fungal lung infections in humans even though we’re constantly exposed. Immune cells called macrophages sit inside the air spaces of the lungs (called alveoli), and these cells eat anything you inhale that could be considered harmful, including fungal spores.

Risks for compromised immune systems

However, there are many people whose immune systems are not able to remove fungal spores, and in these cases the fungi can cause dangerous infections or make underlying health conditions (such as asthma) much worse.

People who have damaged or compromised immune systems are at higher risk of becoming seriously unwell from fungal infections. Moulds like aspergillus cause infections in patients with limited immune function, or who have lung damage from diseases like asthma, cystic fibrosis and chronic obstructive pulmonary disease (COPD) associated with heavy smoking.

In people with asthma, the immune system overreacts to triggers (including fungal spores) causing inflammation in the lung. This inflammation makes it more difficult to breathe by reducing the size of the airways. The same type of immune response is responsible for the symptoms of asthma and allergic responses, and fungal spores can also trigger these same types of immune responses. This means that fungal spores can be a particularly powerful trigger for some people.

In very extreme cases, the fungal spores don’t just cause inflammation but can invade the airways and block them leading to bleeding within the lung. This happens when spores germinate and form long spiderweb-like projections called mycelium which create sticky lumps that block airways and damage the delicate tissues of the lung.

Growing resistance

Aspergillus infections are treated with antifungal drugs called azoles, which prevent the fungal cells from forming properly. Azoles are very effective, but there are increasing rates of resistance to azoles reported in aspergillus which is a significant cause for concern.

We have a limited range of antifungal drugs available to treat mould infections – and when resistance develops this can severely reduce the options a patient has for treatment.

Resistance to drugs such as azoles can develop in patients who take these drugs for long periods of time, but recent research has indicated that resistance is more commonly developing in the environment, where most fungi are found. This means that even before a patient is diagnosed with an aspergillus infection, it may already be too late for the antifungal drugs to be effective.

Development of drug resistance in environmental fungi has been linked to use of azoles and other antifungal drugs in farming. Fungal infections are a big problem for crops, and plants need protection from these infections the same way we do. Unfortunately, the same drugs we use in the clinic are the same types that are being used in agriculture.

Climate change may also be driving drug resistance in environmental fungi. Exposure to high temperatures was recently found to help moulds develop resistance to commonly prescribed antifungal drugs. There have also been reports of patients becoming ill from species of mould that were not thought to cause human disease, in part because they could not grow at the human body temperature.

More mould species could therefore be picking up the ability to cause infections, as well as becoming drug resistant. Research programs and healthcare initiatives that monitor for these changes are vital to help us become prepared for potential increases in mould infections.

While a healthy immune system means that typical exposure to fungal spores is not likely to cause you any health problems, being exposed to very large amounts of fungal spores can prove to be fatal even for people who don’t have underlying health issues.

In 2020, toddler Awaab Ishak died as a direct result of high exposure to fungal spores, caused by excessive damp and mould in his home.

His death led to a change in UK law (Awaab’s Law) which requires landlords to respond promptly to damp in homes they manage, to ensure that tenants are not exposed to excessive levels of fungal spores which can affect their physical and mental health.

It’s important, then, to help keep your home free of mould. The best way to do this is ensure you have good ventilation and take other measures to reduce damp, such as using a dehumidifier or investing in a heated clothes rack to dry your clothes indoors in the winter. Läs mer…

When Donald Trump joined Elon Musk for a live interview on X (formerly Twitter) late last year, the conversation covered a range of significant topics: his near-assassination, Biden’s withdrawal from the race, and the future of the presidency. However, for many viewers, an unexpected detail stole the spotlight: Trump’s slurred speech and lisp.

Was Trump wearing dentures? The public certainly seemed to think so. Throughout the interview, the word “dentures” was mentioned over 15,000 times on X and the interview sparked the resurgence of the hashtag #DenturedDonald.

Why does this matter? Trump is, after all, 78 years old, and a 2017 survey showed that nearly one in four Americans aged 75 and older have no teeth left at all. However, presidential dental health has long had an impact on public perception and leadership itself. From George Washington’s infamous dentures to Teddy Roosevelt’s toothy grin, a president’s teeth (or lack thereof) have often shaped the way they are seen by the American public.

Since the appointment of George Washington as the first US president, it has been tradition for each new president to commission a portrait of themselves during their time in office. However, it was not until Ronald Reagan’s portrait, completed in 1991, that we saw a president depicted with a smile.

This is partly to do with practicality – many early portraits were painted from life, and sitting with a smile for hours was almost impossible – and partly to do with etiquette. In the 18th century, a wide smile was considered a sign of lewdness and drunkenness and associated largely with the lower classes.

Indeed, a 1703 text on “decorum and civility” said that some people part their lips so that “their teeth are almost entirely visible. This is entirely contradictory to decorum, which forbids you to allow your teeth to be uncovered, since nature gave us lips to conceal them.”

It is often suggested that historical portraits avoided smiles because of poor dental hygiene, but in reality, social conventions played a much larger role. For earlier presidents, maintaining an image of sobriety, morality and respectability was important, and a serious expression was seen as a reflection of these values.

This all changed with Teddy Roosevelt. When Roosevelt became the 25th US president in 1901, photography was becoming much more accessible. Technological advancements and the introduction of handheld cameras meant that photography could be practised by a much broader range of people.

Because of this, Roosevelt was often candidly photographed while laughing or smiling, leading to his reputation as “the first president who smiled”.

Teddy Roosevelt – the ‘first smiling US president’.
ClassicStock / Alamy Stock Photo

He even capitalised on his grin in his 1904 campaign by releasing the Teddy’s Teeth Whistle. Retailing at five cents (US$1.77 or £1.44 in today’s money), supporters were encouraged to buy a set and “blow the horn for Teddy”.

Roosevelt’s embrace of his smile and the promotion of his teeth marked a shift in how a president’s image could be used to influence public perception, showing that good dental health could be a powerful political tool.

Worse than wood

Not all presidents were as diligent as Roosevelt when it came to dental hygiene. George Washington, for example, was infamous for his poor dental health.

His letters, diaries and financial accounts reveal a long history of dental troubles, ultimately leading to his use of dentures. However, contrary to popular belief, Washington’s dentures were not made of wood. Instead, they were made from materials including ivory, animal teeth and human teeth.

One of Washington’s account books reveals that he bought nine teeth from enslaved people on his Mount Vernon plantation. This detail adds a sinister layer to the history of Washington’s dental care because, while these people were paid for their teeth, their enslaved status probably left them with little choice in the matter.

Washington’s poor dental hygiene also extended to his care of his dentures. They became notoriously stained, largely due to his fondness for rich red wine. One letter from his dentist chastised him for the condition of his dentures, stating: “The set [of dentures] you sent me from Philadelphia … was very black, occasioned either by your soaking them in port wine, or by your drinking it. I advise you to either take them out after dinner and put them in clean water … or clean them with a brush.”

These insights into Washington’s dental struggles underscore the lasting effect of oral health on the presidential image.

Presidential dental health has played, and continues to play, an important role in shaping public perception, with teeth often serving as symbols of both personal care and political power. Whether influencing how a president is seen or reflecting broader social attitudes, the state of a leader’s teeth has clearly left its mark on the history of the office. Läs mer…

In early December 2024, hopes for a landmark global treaty to curb plastic pollution were dashed as negotiations in South Korea stalled. Leading the campaign against the deal were major oil-producing nations, especially Saudi Arabia and Russia, who argued for a more flexible approach to any legally binding limits on plastic manufacturing.

The collapse of any agreement came despite scientific research delivering ever more alarming warnings about the dangers of plastic pollution. Over the last two years, an avalanche of studies have revealed the pervasive presence of tiny plastic particles in human blood, brains, and even placental tissue.

These particles, which stem from the breakdown of larger plastic waste, have been linked to everything from inflammation to hormonal disruption, and potential long-term health risks such as cancer. Aside from their effects on human health, plastics are wreaking havoc on marine ecosystems, with microplastics now found in Arctic ice and in the bodies of fish and birds.

Behind these alarming studies stands a seemingly unstoppable juggernaut of plastic production. The annual global production of plastics reportedly grew nearly two hundredfold between 1950 (two million tonnes) and 2015 (381 million tonnes), and the pace of growth is accelerating.

Over half of all plastics ever made were produced in the past 25 years, and production levels are estimated to double or triple again by 2050. And more production brings more waste.

Less than 10% of all plastics ever produced have been recycled. And the volume of “mismanaged plastics” – those which are not recycled, incinerated, or sealed in landfills – is also estimated to double by 2050.

It seems as if humans have become the organic detritus within a plastic world of our own creation.

Plastic elephants

But despite growing awareness around the problems associated with plastic, there is a fundamental flaw in how we tend to think about it as a product.

For there is a tendency to frame plastic as a problem of pollution and recycling, rather than as an integral part of our fossil fuel-driven world. This narrative is also promoted by major oil companies, such as the American giant, ExxonMobil, which stated in the lead up to the South Korean summit: “The issue is pollution. The issue is not plastic.”

The problem with this perspective is that it obscures the fact that plastics are petrochemical products: substances which are ultimately derived from oil and gas.

Indeed, the future of fossil fuels is increasingly tied to the future of plastics. It has been estimated that by 2040, plastics will account for as much as 95% of net growth in oil demand.

This is perhaps why 220 fossil fuel lobbyists attended those recent treaty discussions, outnumbering all other delegations. It could also explain why Saudi Arabia, home to one of the world’s largest petrochemical companies, led the opposition to any global limits on plastic production.

At the core of capitalism

The problem we confront is not simply the presence of an oil lobby, it is the systemic role that plastics play within capitalism.

Plastics, and the wider petrochemical industry, played a crucial part in the transformation of global capitalism from the mid-20th century onwards.

As I explore in my book, Crude Capitalism, the things we used to need to build and make things previously relied on sourcing naturally occurring, labour-intensive goods like timber, cotton or metals. But the invention of plastics and other synthetic materials separated commodity production from nature.

More plastic in the pipeline.
Kodda/Shutterstock

Oil became more than a fuel – it was the substance that came to dominate our lives. A petrochemical shift to the rise of an oil-dominated world. With capitalism untethered from natural cycles, there was a radical reduction in the time taken to produce commodities and an end to any limits on the quantity and diversity of goods produced.

Along with this, consumption habits became centred around notions of disposability and obsolescence. Plastics made the essential features of contemporary capitalism possible: a drive to limitless growth, continual acceleration of production and consumption, and the frenzied expansion of markets.

The emergence of fast fashion is just one example. Alongside poorly paid garment workers in countries such as Bangladesh, really cheap clothing was only made possible through the massive expansion of polyester production (a kind of plastic), which freed the industry from its dependence on supplies of wool and cotton.

The consumption of plastics looms large in today’s ecological crisis. And having become so accustomed to thinking about oil and gas as primarily an issue of energy and fuel choice, perhaps we have lost sight of how much of our lives depend upon the products of petroleum.

These synthetic materials drove a post-war revolution in productivity, bringing labour-saving technology and mass consumption. It is now almost impossible to identify an area of life that has not been radically transformed by the presence of plastics and other petrochemicals.

Plastic products have become normalised as natural parts of our daily existence. And it is this paradox which must be fully confronted if we are to move beyond fossil fuels. Läs mer…

Ooboo Vroose Baa Dooo! That’s “happy birthday” in Simlish, the delightfully nonsensical language of The Sims. The life simulation video game franchise turns 25 this year, making me feel officially old.

Like many others, I grew up playing The Sims, oscillating between designing dream homes and orchestrating ideal careers, and trapping my Sim characters in a tiny block room, removing all the doors and watching the chaos ensue. For the more benevolent among us, The Sims was an endlessly rewarding digital dollhouse.

Game designer Sid Meier (creator of the Civilisation series) defines a video game as “a series of interesting decisions”. In most games, interesting decisions are about which gun to use or which party member to heal. The Sims’ interesting decisions, however, were far more mundane. “What clothes should I make my simulated human (typically a digital avatar of myself or my friends) wear?”; “Who should they date?”; and, most importantly: “Should I use the ‘rosebud’ cheat to give myself infinite money?”

The Sims went on to become one of the bestselling franchises of all time, with myriad sequels, expansions and an obsessed player base. While similar titles at the time, such as Black and White, had you playing as an omnipotent god, they were primarily strategy games based around controlling territory. What made The Sims special was its focus on emergent narratives – player-driven experiences where players could create their own stories.

Sul Sul! This article is part of a mini series from The Conversation marking 25 years of The Sims franchise.

Much of this focus is also present in what is now called the “cosy game” genre. These are games that focus not on conflict or challenges, but rather on creativity, exploration and personal expression.

Before Stardew Valley let us befriend a moody fisherman, Animal Crossing allowed us to be financially terrorised by a raccoon, and Unpacking made us cry over a box of kitchen utensils, The Sims showed us a new way to play. One where the biggest challenge was forgetting to pay your bills, and the most rewarding accomplishment was finally affording a pool (whose exit ladder may or may not just have mysteriously disappeared).

This normalised the idea that games didn’t need to be won to be fun. It was a shift in design philosophy that paved the way for later games that let players tend a farm, manage a café, or befriend ghosts without a game-defined goal.

A trailer for one of the more recent expansion packs, Cottage Living.

The Sims was less about victory than it was about making your own fun – whether that meant imagining your future family life with your crush, or seeing how well you could build your Sim’s career from the ground up before succumbing to late-stage capitalism.

Copying The Sims’ homework

Many features that define the cosy game genre today trace directly back to The Sims. It popularised meticulous environment building and customisation tools, for example, from house layouts to outfit choices and suspiciously elaborate hedge mazes. This DNA is the bedrock of many modern cosy games, like Tiny Glade’s whimsical castle-building or pandemic hit Animal Crossing: New Horizons’ island growing.

The Sims was free from combat or major stressors (unless you count fire hazards and rogue Grim Reapers). No timers, no pressure – just vibes (unless you forgot to build a toilet, in which case the vibes would be bad). You could play at your own pace, which came to define other self-paced games like A Short Hike.

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

Much of The Sims was about the relationships between the Sims themselves. They could get married, have children, make friends and even enemies. Instead of fighting for survival, Sims were fighting for their relationships.

This was augmented by a growing “machinima” fan culture, where players made short films and movies using in-game footage. These forms of emergent, social storytelling are a mainstay of modern gaming and meme culture, made even more prevalent by social media and the “share” buttons now on many game controllers.

In this work of machinima, a Sims player has made a sitcom trailer using footage from their gameplay.

Over the years, The Sims franchise has become a bastion for diversity, equity and inclusion. Most recently, that’s meant allowing players to create disabled and transgender Sims.

This provides more representation to players, and showcases the importance of cosy games for exploring an array of identities, values and stories. The move has even inspired copycats like the upcoming Inzoi, which provides even more realistic graphics and complex life simulation, building on the formula introduced by Sims creator Will Wright all those years ago.

For 25 years, The Sims has proven that games can be different. They don’t need conflict, challenge or even victory to be engaging. Sometimes, the real joy comes from designing an entire town, crafting a chaotic soap opera – or simply watching a Sim pace around a door-less room, gradually descending into madness. Läs mer…