Emetophobia: what it’s like to have a fear of vomiting

Source: The Conversation – UK – By Molly Sheila Harbor, PhD Candidate in Psychology, University of Reading

Emetophobia can have a serious impact on a person’s daily life. Nicoleta Ionescu/ Shutterstock

It’s safe to say nobody likes vomiting. But while it’s not a pleasant experience by any means, few of us really give much thought to it – except maybe when we’ve had a few too many drinks or when stomach flu is doing the rounds.

But for around 2%-7% of the population, vomiting) provokes anxiety so severe they’ll do anything to avoid it. This specific fear of vomiting is known as emetophobia. Though much about the condition remains unknown, research is beginning to explore the debilitating impact it can have on sufferers.

Emetophobia affects everyone differently. For some, this fear centres around vomiting themselves, while for others it’s a fear of seeing somebody else vomit. Many also experience a combination of both fears. Some people can also pinpoint a specific traumatic event related to their phobia, while for others there is no distinct cause.

Emetophobia can also have varying degrees of impact on a person’s life – ranging from mild to debilitating, according to a recent review my colleagues and I published.

The most common characteristic of emetophobia is avoidance. People with the condition often steer clear of situations where they think vomit might be a risk. Many avoid public transport, crowded places, theme parks, dining at restaurants or consuming alcohol. Some even go so far as refraining from saying or typing the word “vomit.”

This fear and avoidance can even influence long-term life decisions – with some people avoiding pregnancy and children due to concerns with morning sickness and the illnesses (such as stomach flu) that kids are prone to.

Not only can these avoidance behaviours affect social and professional life, they can also have an impact on physical health. For example, some people with emetophobia restrict their diet or avoid certain foods – such as meat, due to perceived risk of Salmonella (a food-borne illness that can cause vomiting). This can result in nutrient deficiencies and becoming underweight.

People have also been shown to engage in compulsive behaviours such as hand washing, magical thinking (the belief that certain habits or specific thoughts can stop vomiting from happening) and excessive cleaning to avoid being sick. These symptoms overlap with other psychiatric disorders – specifically anorexia nervosa and obsessive-compulsive disorder. This has often led to misdiagnosis, with patients referred to services who are not specialised in treating emetophobia.

A young boy refuses the breaded meat which is being offered to him on a fork by another person.
Some with emetophobia will avoid certain foods out of fear of getting sick.
Ground Picture/ Shutterstock

Another common and often overlooked symptom of emetophobia is nausea – with the majority of people experiencing feelings of sickness on a daily basis, despite having no underlying medical condition. As emetophobia goes hand-in-hand with a preoccupation with vomiting, there’s usually a heightened awareness of bodily sensations which can cause anxiety.

Everyday mundane experiences such as feeling overly full after a meal or getting a headache from too much screen time can trigger the automatic thought: “I am going to be sick.” This creates a vicious cycle, as the more attention a person gives to these sensations, the more likely they are to misinterpret them as signs of illness. This in turn reinforces and entrenches the fear.

Treating emetophobia

A lack of research into emetophobia means treating the condition currently remains a hurdle.

Cognitive behavioural therapy (CBT) seems to be the most evidence-based treatment investigated so far. This treatment approach aims to change thought patterns and behaviour. For emetophobia, this involves changing beliefs about vomiting and slowly reducing avoidance habits through exposure – such as visiting feared places and reducing excessive hand-washing.

Although some studies have shown promising results from using CBT for emetophobia, these studies only investigated a small number of participants. This means it’s difficult to draw firm conclusions about the treatment’s effectiveness until larger studies have been done.

Another option is exposure therapy, which has been tried and tested on people suffering from other phobias and has shown great outcomes. Exposure therapy involves gradually facing feared situations with the help of a therapist to teach the brain these things are not dangerous and reduce overall fear.

But it’s worth noting that although exposure therapy is recommended for other phobias, only 6% of people with emetophobia would be willing to try it. This doesn’t make exposure therapy a very accessible option for the majority of people struggling with this disorder.

Further complicating matters is the fact that people with emetophobia often avoid places such as GP surgeries and hospitals because of the risk of seeing someone who is unwell or catching a vomiting bug. This means they struggle to access what help might be available.

There’s a clear need for increased awareness of this condition, from both the general public and doctors. Awareness can help limit misdiagnosis, show sufferers treatment is available and reduce misconceptions.

Emetophobia is more than simply not liking vomit. It can affect every aspect of life. Our continued research aims to explore effective treatment options for this complex disorder.

The Conversation

Molly Sheila Harbor 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. Emetophobia: what it’s like to have a fear of vomiting – https://theconversation.com/emetophobia-what-its-like-to-have-a-fear-of-vomiting-269310

Exhausted employees don’t want it – so why has Greece introduced a 13-hour work day?

Source: The Conversation – UK – By Elena Papagiannaki, Lecturer in Economics, Edinburgh Napier University

Hospitality workers are likely to be hit hard by the law. Mulevich/Shutterstock

The Greek government has passed a law allowing private employers to extend shifts to 13 hours per day, framed in terms of “flexibility” and “growth”. It’s marketed as voluntary and fairly paid, but effectively it dismantles the standard eight-hour day, despite survey data showing workers overwhelmingly oppose it.

But while critics question its legality, technically it does comply with the European Union’s working time directive. For many, especially in hospitality, it simply formalises what already exists: long hours, low pay, little rest.

The reform mirrors a broader European and global shift towards deregulated work. And it proves that the fight for shorter hours is far from over, as I set out in a chapter in the forthcoming book Global Futures of Work: A Critical Introduction.

After Greek workers’ 1936 victory securing the eight-hour day, the country has now reached a point where Greeks are again among the most overworked in Europe. Data from the EU’s statistics office and the Organisation for Economic Co-operation and Development (OECD) show full-time employees log about 1,900 hours a year, compared with 1,510 in the UK and 1,330 in Germany.

Weekly hours add up to 41-42 on average, the highest in the EU. Yet wages and productivity remain low. This paradox of working more but earning less reflects a regime centred on labour intensification and wage suppression, weak collective bargaining and precarious jobs.

Since 2005, Greece has loosened its working time regime under “flexibility” reforms. A 2005 law allowed daily shifts to be stretched by two hours, another change in 2021 redefined overtime, while a third law two years later revived the six-day week.

And now the fair work for all bill permits 13-hour days on a “voluntary” basis. Together, these measures have eroded the eight-hour norm, substituting collective bargaining for the needs of employers.

The Greek government claims that workers want longer days, but the evidence suggests otherwise. The drive to extend working hours masks a refusal to raise real wages and household income. Since the 2008-09 financial crisis, GDP has shrunk by 27% and remains below pre-crisis levels, while household disposable income has fallen by 35 percentage points.

Even the recent minimum-wage hike (a 6% increase to €880 (£775) per week for full-time workers) offers no real gains in purchasing power, leaving workers poorer than before the crisis. Instead of higher pay, the government’s solution is longer days – stretching time when it cannot stretch income.

A survey earlier this year by the Greek labour institute found that 94% of workers support shorter hours with no pay cut, and nearly 60% reject a 13-hour day outright. Among those already working such hours, 70% say the “voluntary” label is meaningless, with workers forced to put in these hours to make ends meet.

For many, the new law simply confirms the overwork they already face. For others, it represents a return to the 19th century. The wave of nationwide strikes demanding its repeal raises a clear question. If workers reject it, and EU law supposedly guarantees the opposite, how can the measure pass?

EU – protector or enabler?

Most opposition parties questioned the 13-hour workday’s legality under EU law, but the EU working time directive itself provides the loophole. It stipulates a 48-hour weekly average and 11 hours’ daily rest, yet imposes no cap on daily hours.

Member states may grant opt-outs, allowing workers to “voluntarily” exceed the limits, effectively legalising overwork. In response to a Greek MEP, the European Commission confirmed that Greece’s reform complies with EU rules. It admitted that the directive allows the 13-hour workday if the 48-hour weekly average is met in the reference period of four months. It is presented as “worker protection”, but this logic simply permits exhaustion now, rest later.

The UK government’s rebuke of South Cambridgeshire District Council for trialling a four-day work week shows that resistance to shorter hours is hardly unique to Greece. Across advanced economies, longer working time has been normalised.

And NHS staff reportedly performed more than 1 million hours of unpaid overtime every week before the pandemic. By 2025, it has been claimed that inefficiencies and delays have added another 7.5 million extra work hours every week across the NHS workforce.

Amazon workers in the US work ten-hour shifts and 55-hour weeks during peak seasons, with similar patterns in the UK. Amazon said its work patterns offer flexible career opportunities and that its staff were the “heart and soul” of its operations. Another elite tech firm looks like following suit: Google’s Sergey Brin actually called for a 60-hour week.

The push to extend working hours is not an anomaly in Greece, but part of a broader trend across advanced economies – the normalisation of overwork in the name of flexibility and growth.

Workers are expected to adapt, erasing boundaries between work and life. Greece’s 13-hour day doesn’t mark progress but a retreat from hard-won labour rights. And it threatens to undo historic victories on working conditions in pursuit of further productivity increases and profits.

The Conversation

Elena Papagiannaki is a Research Fellow at the Institute for the Future of Work (ifow.org)

ref. Exhausted employees don’t want it – so why has Greece introduced a 13-hour work day? – https://theconversation.com/exhausted-employees-dont-want-it-so-why-has-greece-introduced-a-13-hour-work-day-269118

String theory: scientists are trying new ways to verify the idea that could unite all of physics

Source: The Conversation – UK – By Marika Taylor, Pro-vice-chancellor, Professor, University of Birmingham

Image: NASA, ESA, CSA, STScI, Adam Ginsburg (University of Florida), Nazar Budaiev (University of Florida), Taehwa Yoo (University of Florida); Image Processing: Alyssa Pagan (STScI)

In 1980, Stephen Hawking gave his first lecture as Lucasian Professor at the University of Cambridge. The lecture was called “Is the end in sight for theoretical physics?”

Hawking, who later became my PhD supervisor, predicted that a theory of everything – uniting the clashing branches of general relativity, which describes the universe on large scales, and quantum mechanics, which rules the microcosmos of atoms and particles – might be discovered by the end of the 20th century.

Forty-five years later, there is still no definitive theory of everything. The main candidate is string theory, a framework that describes all forces and particles including gravity. String theory proposes that the building blocks of nature are not point-like particles like quarks (which make up particles in the atomic nucleus) but vibrating strings.

It suggests that, if we could look deep inside electrons, we would see loops of strings, vibrating just like those on a violin. Different patterns of string vibrations correspond to different particles.

String theory unifies all the forces of nature. Forces that seem very different, such as gravity and electricity, are deeply related to one another. The forces are linked by so-called dualities: the same underlying phenomena can be described in different ways.

The force of gravity is described in terms of geometry, shapes and positions. Other forces are described in terms of different mathematical concepts, including algebra and numbers.

The unification of forces hence implies profound relationships between branches of mathematics. Such relationships had previously been proposed by mathematicians, particularly by Robert Langlands, and string theory gives physical explanations for the relationships.

Although string theory could be the correct theory of everything, it is hard to test experimentally. The effects of string theory become visible at very small scales and very high energies.

Particle accelerators explore the internal structure of particles by colliding them and breaking them apart. However, even the biggest colliders at Cern in Switzerland don’t have enough energy to break particles down into strings.

Clues in the cosmos

How can we test string theory experimentally if we can’t reach high enough energies in colliders? The answer may lie in looking up to the skies.

The very early universe was dense and hot, and the primordial soup would have been made up of strings. We can see the history of the universe imprinted in current day observations, from surveys of galaxies through to measurements of the cosmic radiation that permeates all of space and is a leftover from the big bang.

In the early 20th century, American astronomer Edwin Hubble showed that the universe is expanding. Galaxies are moving further apart from each other.

At the end of that century, detailed observations of the expansion showed that it is in fact accelerating. Galaxies today are moving apart faster than they were a million years ago.

What is driving this acceleration? Gravity is an attractive force so it slows down the expansion of the universe. The acceleration of the universe is driven by a new kind of energy, which is spread throughout the whole of space. Scientists call this dark energy and it makes up about 70% of the energy of the universe.

We don’t know exactly what dark energy is. The most plausible explanation is that it is the inherent quantum energy of the universe. In the quantum world, particles can never just sit still, with no energy. There is always a little bit of quantum jitter and associated energy.

Atoms cooled down to absolute zero temperature still have energy because of their quantum motion. Dark energy could potentially be explained as being the underlying quantum energy of all the forces and particles in nature, including gravity.

Experiments are pinning down the properties of dark energy. Desi is an observatory based in Arizona, US, which is mapping out galaxies and quasars. The space based telescopes Euclid and Roman will measure the universe in unprecedented detail, mapping out the history of billions of galaxies over billions of years.

Desi sits in the dome of the Nicholas U. Mayall 4-meter Telescope at the Kitt Peak National Observatory.
Desi sits in the dome of the Nicholas U. Mayall 4-meter Telescope at the Kitt Peak National Observatory.
wikipedia, CC BY-SA

Recent results from Desi suggest that dark energy is changing in time in a way that is consistent with string theory models – although this is yet to be fully verified by further measurements.

This doesn’t prove string theory because string theory can produce a variety of different universes, with differing patterns of dark energy. However, the Desi results suggest that interpreting dark energy as quantum energy of strings may be on the right track. There are of course phenomena other than strings that could explain the change in dark energy.

Euclid and Roman will make very precise measurements and will be able to exclude many such theories of dark energy and some specific versions of string theory – helping to narrow down the bits theorists should focus on.

Another way to verify string theory may be via black holes. Once something falls inside a black hole, it cannot escape. Inside a black hole there are very strong forces and particles are torn apart. We still don’t understand exactly what happens inside a black hole, but string theory teaches us how a black hole retains information about what has fallen inside.

That’s because string theory assumes there is no “singularity” inside a black hole – a point of infinite density and gravity – but instead that the objects are spread out as balls of strings called fuzzballs.

Future, more precise, measurements of gravitational waves (ripples in the fabric of spacetime) will be looking for the subtle signals of the quantum behaviour inside black holes predicted by string theory. If black holes are fuzzballs, they should produce a different signal when they merge, lasting longer and containing echoes. What’s more, if extra dimensions exist, as string theory proposes, black holes may oscillate in different ways which we could also detect.

In addition to cosmological measurements, scientists can run thought experiments, just as Einstein did with his theories of relativity. String theory has led to new insights not just in mathematics but also in other areas of science. For example, string theory has proven to be useful in understanding how quantum systems can be used in computing.

I don’t think a complete understanding of a theory of everything is just around the corner, but in the 45 years since Hawking’s Lucasian lecture we have certainly learned a lot. And right now, things are looking up for string theory.

The Conversation

Marika Taylor currently receives funding from EPSRC, STFC, UK government deparments and the European Horizon programme.

ref. String theory: scientists are trying new ways to verify the idea that could unite all of physics – https://theconversation.com/string-theory-scientists-are-trying-new-ways-to-verify-the-idea-that-could-unite-all-of-physics-268149

Apocalyptic images of melting glaciers and sinking islands won’t help anyone imagine a better future

Source: The Conversation – UK – By Natalie Pollard, Professor of Contemporary Literature and Culture, University of Exeter

What do you picture when you think about climate change? For many of us, it is the same set of dramatic images: melting glaciers, sinking landforms, rising seas or extreme weather.

These are powerful visuals. They shock, grab headlines and galvanise environmentalism. However, this imagery offers a partial account of transformation, often underplaying political responsibility and colonial history. In my new book, 21st-Century Climate Imaginaries, I call these charismatic images “climate memes”.

Monumental images of melting or calving glaciers lend drama to earth’s changing form, but tend to bypass the thorny social and economic roots of ice loss. Research shows that glacial melt is accelerating especially in regions at the frontline of resource extraction and colonial occupation. My research asks: why is this?

glacier crashing into sea
The polar effect: house-sized blocks of ice come crashing down into the sea.
Troutnut/Shutterstock

Imagine a glacier melting in the Andes. Blood-red threads of wool – like streams of meltwater – are running down the mountain. It is 2006. This is an activist intervention by Chilean-born artist Cecilia Vicuña. It is the first in her series of performances and soft sculptures, The Blood of the Glaciers. Her giant-order red threads spell out the effects of foreign direct investment in the wake of Augusto Pinochet’s regime, which sparked a dramatic rise in overseas mining corporations in Chile.

Here, as in many regions of the developing world, mining and industrial transportation make the glaciers bleed. The problem is acute because glaciers are water savings banks, essential in years with low rainfall. Glaciers sustain life. Industry-heavy sacrifice zones bleed life dry. Vicuña’s artistic activism shows how extractive mining is a primary driver of glacial recession. Melting is not just a “climate” issue or “natural” disaster. The cause is human activity.

Standing knee-deep in seawater on the shoreline of Tuvalu, the country’s foreign minister addresses Cop26 delegates with these words: “We are sinking”. Simon Kofe’s 2021 speech was broadcast globally from a point that had recently been above sea level. From his semi-submerged podium, Kofe made visible to the world the situation people endure in low-lying Pacific islands.

Tuvalu’s foreign minister, Simon Kofe, delivered his “we are sinking” speech from a podium knee-deep in water.

Since the 1980s, sinking islands have become a powerful shorthand for climate crisis. Apocalyptic spectacles of raging seas symbolise planetary transformation. An often-cited example is the documentary of Al Gore’s An Inconvenient Truth. It showed Tuvalu engulfed by tides, alongside the incorrect remark that “Pacific nations have all had to evacuate”.

In 2009, Marshallese activist Kathy Jetñil-Kijiner joined forces with Greenlandic climate poet Aka Niviâna and environmentalist organisation 350.org. They produced an influential video-poem: Rise: From One Island to Another. The performance connects changing Greenlandic ice and Pacific waters with Indigenous resistance to fossil capitalism.

Rise: From one island to another.

Climate images of melting and sinking often go hand-in-hand with colonial narratives of Indigenous vulnerability. In contrast, Rise brings to life the history of Greenlandic and Marshallese opposition to development for extraction and scientific exploitation. The two activists highlight the nuclear colonial legacy of the Pacific Proving Grounds and Greenland’s Camp Century, linking military histories in the Arctic and Pacific: “nuclear waste / dumped / in our waters / on our ice”.

It is not always easy to remember that environmental change is caused by specific technological, military and political acts. Indigenous arts activism helps by showing how climate memes make sense only in the context of histories of exploitation and resistance, which often take place in developing countries.

Today, activists and artists across the world are challenging popular, generalised climate memes, such as those of melting and sinking. As I show in 21st-Century Climate Imaginaries, attention to the local and specific helps people process how social and environmental violence are intimately linked. Arts activism, working directly with people’s lived experiences of change, can offer much-needed, grounded alternatives to spectacular climate soundbites. How far these interventions are positively reshaping how we understand our responsibilities to a fast-changing world is yet to be seen.


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The Conversation

Natalie Pollard 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. Apocalyptic images of melting glaciers and sinking islands won’t help anyone imagine a better future – https://theconversation.com/apocalyptic-images-of-melting-glaciers-and-sinking-islands-wont-help-anyone-imagine-a-better-future-268909

How the market for international students puts pressure on universities’ academic freedom

Source: The Conversation – UK – By David Yates, Senior Lecturer in Accounting, University of Sheffield

Ground Picture/Shutterstock

It is difficult to ignore the intertwined nature of the commercialised UK higher education model and its reliance on international student fee income. One in four students enrolled in higher education courses in the UK in 2023-24 is of non-UK origin. This is an increase from just over one in five in 2019-20. A total of over £10 billion of universities’ student fee income is raised from non-UK students.

Recent reports that Sheffield Hallam University stymied an academic’s research as a result of pressure from China has thrust the influence that foreign nations may have on UK universities into the spotlight.

Sheffield Hallam has denied that commercial interests played a part in the decision. “For the avoidance of doubt, the decision was not based on commercial interests in China,” a university spokesperson said. “Regardless, China is not a significant international student market for the University.”

For many UK universities, though, international student fees are a vital part of their income. This has followed the reduction of government financial support for universities and successive steps towards marketisation of the higher education sector.

Marketisation means universities compete with each other to attract students, who pay fees for their education. However, fees in the UK are regulated (and Scottish and Welsh governments subsidise students from their respective juridictions) and often do not cover the total cost of teaching and administration of courses. Universities have responded by increasing recruitment of international students to plug the funding gap.

In a marketised model, international students are attractive as their fees are uncapped, meaning that institutions can charge much higher amounts for the same number of students.

Universities are also judged in rankings that include things like how international their student body is, and the ratio of staff to students. Recruiting more international students helps keep the ratio of staff to students lower because higher international student fees mean that fewer students are needed to fund a course.

In 2016-17, international student fee income made up 15.2% of an average institution’s total income. This has risen to 24.6% in 2022-23. This greater reliance on international student fee income as a percentage of overall revenues has been driven by several factors.

Data from the Higher Education Statistics Agency also shows how important individual regions are as part of the overall international student cohort. In 2023-24, the top two countries are India and China. India provided 107,480 students to the UK higher education sector, 25.1% of all international students. China contributed 98,400 students, 23.0% of international students.

Financial risk

The implications of such rises in the proportion of revenues being raised from international student fee income are vast. Most apparent is the increased risk that this exposes UK universities to in terms of volatility in international student numbers.

This is much more unpredictable than changes in government finance, which tend to be announced in advance. Simply put, fluctuations in international student numbers have a big effect on income. And this is a key factor in the current financial crisis in UK higher education.

Marketisation has been linked to cuts that universities are imposing on departments, closing courses and making significant redundancies. This is because greater volatility means that institutions are likely to seek to cut costs such as staff in response to lower revenues, as staff costs represent a large portion of the overall cost base for universities.

The Universities and Colleges Union estimates total job losses within the sector to be in the region of 15,000. Such widespread and rapid cuts are likely to have severe knock on effects for the UK economy as a whole and the universities sector. Industrial action is already affecting the delivery of courses, research activity, and key knowledge exchange and practical impact activities.

Current government policy implies a perseverance with the marketised model, although a proposed 6% levy on international student fees seeks to encourage institutions to pursue more diverse sources of revenue. However, this is unlikely to have any material effect on where institutions draw their students.

The Higher Education Policy Institute has suggested that such a levy could cost an already financially precarious sector in the region of £621 million. Universities may well react by increasing the volume of international students they take on board, as increasing domestic fees may deter home applicants.

Back view of students walking
International student fees are a key part of university revenue.
Daniel Hoz/Shutterstock

Such behavioural effects may well exacerbate such risks in the future. Alternatively, further staff cuts are likely to have prolonged effects for the sector in terms of the quality of education it can provide, and the value delivered to students. Courses may become shorter, student-staff contact time reduced, and optional modules cut.

Rather than focus on one incident, it is the marketised model itself that has landed universities in this the current crisis. They find themselves beholden to the fee income that the market provides. Currently, the need to promise – and provide – a superior experience to their prospective student applicants is driving many financial decisions in the sector.

This includes large amounts of spending on capital projects that has left many institutions with budget deficits and in some cases, heavily depleted cash reserves.

Incentives are required that will encourage sustainable stewardship of our higher education institutions. Until that happens, it is unlikely that anything will change. Capital remains all powerful. The pursuit of it will continue to supplant traditional ideological values of the university, with seemingly no cost too high for universities seeking to “remain in the game”.

The Conversation

David Yates has historically received research funding grants from the British Accounting and Finance Association, the Grantham Centre for Sustainable Futures, and the Joseph Rowntree Foundation, all for projects unrelated to this article. He is a former member of the Labour Party.

ref. How the market for international students puts pressure on universities’ academic freedom – https://theconversation.com/how-the-market-for-international-students-puts-pressure-on-universities-academic-freedom-269007

Sulfur-based batteries could offer electric vehicles a greener, longer-range option

Source: The Conversation – USA (2) – By Golareh Jalilvand, Assistant Professor of Chemical Engineering, University of South Carolina

Sulfur is abundant and inexpensive, making it an attractive ingredient for making batteries. Alanna Dumonceaux/Design Pics Editorial/Universal Images Group via Getty Images

Picture an electric car that could go 600, 700 or even 1,000 miles on a single charge. That’s much farther than the longest-range electric vehicles on the U.S. market, according to Car and Driver magazine – and twice as far the official rating for the long-range, rear-wheel-drive Tesla Model 3, which has a maximum rated range of 363 miles.

Current EVs use lithium-ion batteries, which are also found in smartphones, laptops and even large-scale energy storage systems connected to the power grid. A standard for decades, these batteries have been tweaked and improved by generations of scientists and are now close to their physical limits. Even with the best materials and most optimized designs, there is only so much energy that can be packed into a lithium-ion battery.

I’m a materials engineer who studies these batteries and seeks alternatives with better performance, improved environmental sustainability and lower cost. One promising design uses sulfur, which could boost battery capacity significantly, though some key roadblocks remain before it can be widely used.

Lithium-sulfur vs. Lithium-ion

Any battery has three basic components: a positively charged region, called the cathode; a negatively charged region, called the anode; and a substance called the electrolyte in between, through which charged atoms, also known as ions, move between the cathode and anode.

In a lithium-ion battery, the cathode is made of a metal oxide, typically containing metals such as nickel, manganese and cobalt, bonded with oxygen. The materials are layered, with lithium ions physically between the layers. During charging, lithium ions detach from the layered cathode material and travel through the electrolyte to the anode.

The anode is usually graphite, which is also layered, with room for the lithium ions to fit between them. During discharge, the lithium ions leave the graphite layers, travel back through the electrolyte and reinsert into the layered cathode structure, recombining with the metal oxide to release electricity that powers cars and smartphones.

A schematic diagram of the inner workings of a lithium-sulfur battery.
Lithium-sulfur batteries like this one have different chemistry than more commonly known lithium-ion batteries.
Egibe via Wikimedia Commons, CC BY-SA

In a lithium-sulfur battery, the lithium ions still move back and forth, but the chemistry is different. Its cathode is made of sulfur embedded in a carbon matrix that conducts electricity, and the anode is made primarily of lithium itself, rather than graphite layers with lithium in between.

During discharging, the lithium ions travel from the anode, through the electrolyte to the cathode, where – rather than sliding in between the cathode layers – they chemically convert sulfur in sequential steps to a series of compounds called lithium sulfides. During charging, the lithium ions separate from the sulfide compounds, leave the cathode behind and travel back to the anode.

The charging and discharging process for lithium-sulfur batteries is a chemical conversion reaction that involves more electrons than the same process in lithium-ion batteries. That means a lithium-sulfur battery can theoretically store much more energy than a lithium-ion battery of the same size.

Sulfur is inexpensive and abundantly available worldwide, meaning battery manufacturers do not need to rely on scarce metals such as nickel and cobalt, which are unevenly distributed on Earth and often sourced from regions such as the Democratic Republic of Congo, which has limited worker safety regulations and fair labor practices.

Those advantages could deliver batteries with far more capacity and that are cheaper and more sustainable to produce.

Why aren’t lithium-sulfur batteries widely used yet?

The biggest obstacle to mass production and use of sulfur-based batteries is durability. A good lithium-ion battery, like those in an electric vehicle, can go through thousands of cycles of discharging and recharging before its capacity starts to fade. That amounts to thousands of car rides.

But lithium-sulfur batteries tend to lose capacity much more quickly, sometimes after fewer than 100 cycles. That’s not very many trips at all.

The reason lies in the chemistry. During the chemical reactions that store and release energy in a lithium-sulfur battery, some of the lithium sulfide compounds dissolve into the liquid electrolyte of the battery.

When that happens, those amounts of both sulfur and lithium are removed from being used in any remaining reactions. This effect, known as “shuttling,” means that with each round of discharging and recharging, there are fewer elements available to release and store energy.

In the past couple of decades, research has produced improved designs. Earlier versions of these batteries lost much of their capacity within a few dozen discharge–recharge cycles, and even the best laboratory prototypes struggled to survive beyond a few hundred.

New prototypes retain more than 80% of their initial capacity even after thousands of cycles. This improvement comes from redesigning the key parts of the battery and adjusting the chemicals involved: Special electrolytes help prevent the lithium sulfides from dissolving and shuttling.

The electrodes have also been improved, using materials such as porous carbon that can physically trap the intermediate lithium sulfides, stopping them from wandering away from the cathode. This helps the discharge and recharge reactions happen without so many losses, making the reactions more efficient so the battery lasts longer.

The road ahead

Lithium-sulfur batteries are no longer fragile laboratory curiosities, but there are significant challenges before they can become serious contenders for real-world energy storage.

In terms of safety, lithium-sulfur batteries have a less volatile cathode than lithium-ion batteries, but research is continuing into other aspects of safety.

Another problem is that the more energy a lithium-sulfur battery stores, the fewer cycles of charging it can handle. That’s because the chemical reactions involved are more intense with increased energy.

This trade-off may not be a major obstacle for using these batteries in drones or grid-level energy storage, where ultrahigh energy densities are less critical. But for electric vehicles, which demand both high energy capacity and long cycle life, scientists and battery researchers still need to sort out a workable balance. That means the foundation for the next generation of lithium-sulfur batteries is likely still a few years down the road.

The Conversation

Golareh Jalilvand receives funding from NantG Power LLC, and the US Department of Energy for research on lithium-sulfur batteries.

ref. Sulfur-based batteries could offer electric vehicles a greener, longer-range option – https://theconversation.com/sulfur-based-batteries-could-offer-electric-vehicles-a-greener-longer-range-option-263896

Want to make America healthy again? Stop fueling climate change

Source: The Conversation – USA (2) – By Jonathan Levy, Professor and Chair, Department of Environmental Health, Boston University

Extreme heat can threaten human health, but it’s only one way climate change puts lives at risk. Drew Angerer/Getty Images

If you’ve been following recent debates about health, you’ve been hearing a lot about vaccines, diet, measles, Medicaid cuts and health insurance costs – but much less about one of the greatest threats to global public health: climate change.

Anybody who’s fallen ill during a heat wave, struggled while breathing wildfire smoke or been injured cleaning up from a hurricane knows that climate change can threaten human health. Studies show that heat, air pollution, disease spread and food insecurity linked to climate change are worsening and costing millions of lives around the world each year.

The U.S. government formally recognized these risks in 2009 when it determined that climate change endangers public health and welfare.

However, the Trump administration is now moving to rescind that 2009 endangerment finding so it can reverse U.S. climate progress and help boost fossil fuel industries, including lifting limits on greenhouse gas emissions from vehicles and power plants. The administration’s arguments for doing so are not only factually wrong, they’re deeply dangerous to Americans’ health and safety.

Health risks and outcomes related to climate change.
Health risks and outcomes related to climate change.
World Health Organization

As physicians, epidemiologists and environmental health scientists who study these effects, we’ve seen growing evidence of the connections between climate change and harm to people’s health. More importantly, we see ways humanity can improve health by tackling climate change.

Here’s a look at the risks and some of the steps individuals and governments can take to reduce them.

Extreme heat

Greenhouse gases from vehicles, power plants and other sources accumulate in the atmosphere, trapping heat and holding it close to Earth’s surface like a blanket. Too much of it causes global temperatures to rise, leaving more people exposed to dangerous heat more often.

Most people who get minor heat illnesses will recover, but more extreme exposure, especially without enough hydration and a way to cool off, can be fatal. People who work outside, are elderly or have underlying illnesses such as heart, lung or kidney diseases are often at the greatest risk.

Heat deaths have been rising globally, up 23% from the 1990s to the 2010s, when the average year saw more than half a million heat-related deaths. Even in the U.S., the Pacific Northwest heat dome in 2021 killed hundreds of people.

Climate scientists predict that with advancing climate change, many areas of the world, including U.S. cities such as Miami, Houston, Phoenix and Las Vegas, will confront many more days each year hot enough to threaten human survival.

Extreme weather

Warmer air holds more moisture, so climate change brings increasing rainfall and storm intensity, worsening flooding, as many U.S. communities have experienced in recent years. Warm ocean water also fuels more powerful hurricanes.

Increased flooding carries health risks, including drownings, electrocution and water contamination from human pathogens and toxic chemicals. People cleaning out flooded homes also face risks from mold exposure, injuries and mental distress.

A man carries boxes out of a house that flooded up to its second story.
Flooding from hurricanes and other extreme storms can put people at risk of injuries during the cleanup while also triggering dangerous mold growth on wet wallboard, carpets and fabric. This home flooded up to its second flood during Hurricane Irma in 2017.
Sean Rayford/Getty Images

Climate change also worsens droughts, disrupting food supplies and causing respiratory illness from dust and dry conditions as well as wildfires. And rising temperatures and aridity dry out forest and grasslands, making them more vulnerable to catching fire, which creates other health risks.

Air pollution

Wildfires, along with other climate effects, are also worsening air quality around the country.

Wildfire smoke is a toxic soup of microscopic particles (known as fine particulate matter, or PM2.5) that can penetrate deep in the lungs and hazardous compounds such as lead, formaldehyde and dioxins generated when homes, cars and other materials burn at high temperatures. Smoke plumes can travel thousands of miles downwind and trigger heart attacks and elevate lung cancer risks, among other harms.

Meanwhile, warmer conditions favor the formation of ground-level ozone, a heart and lung irritant. Burning of fossil fuels also generates dangerous air pollutants that cause a host of health problems, including heart attacks, strokes, asthma flare-ups and lung cancer.

Infectious diseases

Because they are cold-blooded organisms, insects are directly influenced by temperature. So as temperatures have risen, mosquito biting rates have risen as well. Warming also shortens the development time of disease agents that mosquitoes transmit.

Mosquito-borne dengue fever has turned up in Florida, Texas, Hawaii, Arizona and California. New York state just saw its first locally acquired case of chikungunya virus, also transmitted by mosquitoes.

A world map shows where mosquitos are most likely to transmit the dengue virus
As global temperatures rise, regions are becoming more suitable for mosquitoes to transmit dengue virus. The map shows a suitability scale, with red areas already suitable for dengue transmissions and yellow areas becoming more suitable.
Taishi Nakase, et al., 2022, CC BY

And it’s not just insect-borne infections. Warmer temperatures increase diarrhea and foodborne illness from Vibrio cholerae and other bacteria and heavy rainfall increases sewage-contaminated stormwater overflows into lakes and streams. At the other water extreme, drought in the desert Southwest increases the risk of coccidioidomycosis, a fungal infection known as valley fever.

Other impacts

Climate change can threaten health in numerous other ways. Longer pollen seasons can increase allergen exposures. Lower crop yields can reduce access to nutritious foods.

Mental health can also suffer, with anxiety, depression and post-traumatic stress following disasters, and increased rates of violent crime and suicide tied to high-temperature days.

A older man holds a door for a woman at a cooling center.
New York and many other cities now open cooling centers during heat waves to help residents, particularly older adults who might not have air conditioning at home, stay safe during the hottest parts of the day.
Angela Weiss/AFP via Getty Images

Young children, older adults, pregnant women and people with preexisting medical conditions are among the highest-risk groups. Often, lower-income people are also at greater risk because of higher rates of chronic disease, higher exposures to climate hazards and fewer resources for protection, medical care and recovery from disasters.

What can people and governments do?

As an individual, you can reduce your risk by following public health advice during heat waves, storms and wildfires; protecting yourself against tick and mosquito bites; and spending time in green space that improves your mental health.

You can also make healthy choices that reduce your carbon footprint, such as:

However, there are limits to what individuals can do alone.

Actions by governments and companies are also necessary to protect people from a warmer climate and stop the underlying causes of climate change.

Workplace safety can be addressed through rules to reduce heat exposure for people who work outdoors in industries such as agriculture and construction. Communities can open cooling centers during heat waves, provide early warning systems and design drinking water systems that can handle more intense rainfall and runoff, reducing contamination risks.

Governments can ensure that public transit is available and not overly expensive to reduce the number of vehicles on the road. They can promote clean energy rather than fossil fuels to cut emissions, which can also save money since the cost of solar energy has dropped spectacularly. In fact, both solar and wind energy are less expensive than fossil fuel energy.

Yet the U.S. government is currently going in the opposite direction, cutting support for renewable energy while subsidizing the fossil fuel industries that endanger public health.

To really make America healthy, in our view, the country can’t ignore climate change.

The Conversation

Jonathan Levy receives funding from the National Institutes of Health, the Federal Aviation Administration, the City of Boston, and the Mosaic Foundation.

Howard Frumkin has no financial conflicts of interest to report. He is a member of advisory boards (or equivalent committees) for the Planetary Health Alliance; the Harvard Center for Climate, Health, and the Global Environment; the Medical Society Consortium on Climate Change and Health; the Global Consortium on Climate and Health Education; the Yale Center on Climate Change and Health; and EcoAmerica’s Climate for Health program—all voluntary unpaid positions.

Jonathan Patz receives funding from the National Institutes of Health. He is affiliated with the Medical Society Consortium for Climate and Health, and its affiliate Healthy Climate Wisconsin.

Vijay Limaye is affiliated with the Natural Resources Defense Council.

ref. Want to make America healthy again? Stop fueling climate change – https://theconversation.com/want-to-make-america-healthy-again-stop-fueling-climate-change-269269

How a Sudanese university kept learning alive during war

Source: The Conversation – Africa – By Gihad Ibrahim, Assistant Professor and E-learning Department Head, Mashreq University

The civil war in Sudan began in April 2023, causing death, hunger, displacement and destruction on a huge scale. Gihad Ibrahim, head of e-learning and senior manager at Mashreq University in Sudan’s capital, Khartoum, spoke with The Conversation Africa about how his institution continued to educate thousands of students despite the destruction of its campuses during the ongoing conflict.

What was Mashreq University like before the war?

Mashreq University (established in 2003) was a thriving academic community of over 10,000 students across 10 faculties, including healthcare, engineering, information technology and business. We were known for innovation, being the first in Sudan to offer degrees in fields like artificial intelligence and mechatronics engineering. We ranked highly in both global and national rankings.

Our status as a private university allowed us agility in decision-making and investing in digital infrastructure early, a crucial factor in our later survival. However, our success was also rooted in operating within a national system that, before the war, permitted and accredited such innovation. This highlights a vital policy lesson: governments can foster resilience not by micromanaging, but by creating a regulatory environment that allows universities the autonomy to adapt and invest in their own futures.

Our main campus was in Khartoum North, a hub of student life.

While teaching was primarily in-person, we had already begun integrating online elements for some courses. This digital foundation, though modest, would later become our lifeline.

We established a learning management system back in 2013. When the COVID-19 pandemic struck in 2020, we were among the few Sudanese universities that could transition seamlessly online.

That crisis was a dress rehearsal; it forced us to build a system for blended learning that saved us when a far greater crisis emerged.

What happened when the fighting broke out in April 2023?

The war began on a Saturday morning – a normal teaching day. Students were already commuting. I remember I had a morning meeting with three female students working on their graduation project. I called one of them immediately and told her to warn the others and return home. Unfortunately, one didn’t get the message and was trapped near campus for two weeks – a harrowing reminder of the immediate human cost.

Our first priority was evacuation. But in those first chaotic hours, our information technology team performed a critical act: an emergency cloud backup of all academic records. It was a decision born of foresight, and it preserved the academic history of thousands.

Within weeks, our main campus was occupied by the paramilitary Rapid Support Forces (RSF). They looted laboratories and burned lecture halls. Because of the buildings’ height, they used them as military positions. Our campus was not just damaged; it was weaponised.

How did you keep teaching after such devastation?

Khartoum became a ghost city. With people fleeing in all directions – to other states or across borders to neighbouring countries like Egypt and Saudi Arabia – our university community scattered. The first step was to find them. We launched an online survey to locate our displaced students and staff.

Using that data, we established a network of “teaching centres” in safer locations. We created hubs in Port Sudan (after relocating from the city of Atbara), and internationally in Cairo (in Egypt), Jeddah (in Saudi Arabia), and a virtual campus in the United Arab Emirates (UAE). The UAE group was smaller, but because many students there held temporary “war victim” visas that restricted travel, we offered live virtual classes instead of physical ones.

How does this new teaching model work?

We had to be strategic. We categorised every course:

Non-applied courses (like many in business or theory) moved entirely online.
Applied courses (like lab sciences) were delivered face-to-face at the teaching centres.

Advanced specialised courses were taught live online to all centres simultaneously.

Consistency was key. Each course had a “lead lecturer” who coordinated content across all locations to ensure every student received the same quality. We partnered with local hospitals and factories for practical training, turning a constraint into an opportunity for real-world learning.

Exams were held online on university tablets, but invigilated in person at the centres to ensure integrity. The system was built on flexibility, but also on rigorous standards.

What lessons has Mashreq University learned?

We learned three profound lessons:

Technology is a lifeline. Our pre-war investment in digital infrastructure was what allowed us to survive.

Flexibility and compassion must replace rigid bureaucracy. We focused on the goal – education – not on the old rules.

Crisis can fuel innovation. Many students gained deeper, more relevant experience training in real hospitals and factories than they ever would in a simulated campus lab.

The most powerful moments have been the messages from graduates. They write to thank us, often noting that their peers at other universities are still waiting, their education frozen. One message captures it all:

You gave me my future back.

This reminds us that education is not a luxury; in times of war, it is a testament to normalcy, hope, and the future.

What comes next?

We have already begun refurbishing our main campus in Khartoum North, hoping to return soon. But the old model is gone for good.

This experience has taught us that education has no borders. It can reach anyone, anywhere, if guided by compassion and strategic purpose.

For universities everywhere, our story is a stark lesson: investing in resilient, flexible systems is not just about innovation; in today’s world, it is fundamentally about survival.

The Conversation

Gihad Ibrahim works as the Head of E-learning department at Mashreq University

ref. How a Sudanese university kept learning alive during war – https://theconversation.com/how-a-sudanese-university-kept-learning-alive-during-war-269325

Nana Konadu Agyeman-Rawlings: the first lady who redefined women’s power in Ghana.

Source: The Conversation – Africa (2) – By Nancy Henaku, Lecturer, Department of English, University of Ghana

Tributes for Nana Konadu Agyeman-Rawlings (1948-2025) have been pouring in since her death on 23 October 2025. For many Ghanaians, her broad-ranging empowerment work as leader of the 31st December Women’s Movement is deserving of full recognition. The non-governmental organisation started as a women’s political movement and is still active.

Born on 17 November 1948, she became the wife of Jerry John Rawlings, who governed Ghana from 1981 until he handed over power in 2001.

Mourners, including Ghana’s President John Dramani Mahama, have referenced Agyeman-Rawlings’ social welfare interventions through her organisation as evidence of her achievements. These include the provision of credit facilities and advocacy for women’s and children’s rights. She also established daycare centres for children, adult literacy centres and edible oil extraction industries.

A dimension of Agyeman-Rawlings’ politics that has been mainly overlooked, however, is her rhetorical leadership. This refers to the various persuasive means through which she performed her roles as a public figure.

I am a scholar of English who studies how people use language and other communicative forms (such as sound and visuals) to influence public discourse. I have used rhetorical and linguistic methods to study various sources on Agyeman-Rawlings, including a personal interview I conducted with her in 2017.

Agyeman-Rawlings’ speeches and writing reveal her motivations for shifting prevailing ideas about women’s social roles, her complex responses to public anxieties about her power (real or imagined) and her attempt at disrupting the archives by narrating herself into history.

Advocating for change

Agyeman-Rawlings’ rhetorical leadership transformed the role of the first lady in Ghana. In her own words:

A first lady’s work does not end with the collection of flowers and doing some protocols … I’d rather work and be emulated than to sit down and not do anything and not change anybody’s life.

For this reason, Agyeman-Rawlings spoke and wrote extensively in national and international contexts. Her rhetoric of empowerment centred the plights of women, children and the poor. For instance, she asserted at Beijing that “for us in Africa, the girl child is a special concern.”

Agyeman-Rawlings articulated a cosmopolitan ideology shaped by multiple influences. These include UN rights discourses, the language of mothering (such as nurturing, protecting), liberal feminism with its emphasis on gender reform through legal means, and the populist rhetoric of the Rawlings regime, with its emphasis on people power.

An assessment of Agyeman-Rawlings’ legacy must recognise that speaking and writing for change involve extensive physical, mental and emotional energy. And for many years, under her husband’s military regime, she performed this role without the professional support of a communications team.

The sociologist Mansah Prah describes Agyeman-Rawlings’ tenure as the era of the “grand feminist illusion” because although her organisations were seemingly pro-woman, their activities did not result in substantial changes in the lives of women.

However, as my research suggests, discussions on the limitations of Agyeman-Rawlings’ advocacy must consider at least two factors. First, the patriarchal postcolonial state always constrains women’s mass efforts at transformation. Second, the discourses that influence Agyeman-Rawlings’ rhetoric are themselves contradictory. For instance, the term “empowerment” is a catchall phrase that means different things to different people. Its vagueness makes it a safe political term. It does not radically shift conversations on gender.

Contesting power

Agyeman-Rawlings had an intense political life. One could say that through her gendered advocacy and mass mobilisation, she politicised the first lady role. For that reason, she was highly scrutinised during her active political years. In response to efforts to restrain her power, she drew on ambiguous gendered rhetorics, moral values and familial legacy

She was variously accused of being corrupt, power drunk and ostentatious, often with sexist undertones.

People rumoured that she, as first lady, was the real power behind the presidency. When her husband was preparing to leave office, there were stories that she wanted to succeed him. One news report claims that she countered such allegations by saying: “I have never said anywhere that I want to be president” while implying that she could change her mind if her husband said so. It takes a keen rhetorical intellect to navigate the slippery political terrain Agyeman-Rawlings found herself in.

She remained politically active after her tenure as first lady ended. In 2011, she contested against John Evans Atta Mills, Ghana’s president at the time, for the candidacy of the National Democratic Congress, which she helped form. She would later defect from the party to form her own, the National Democratic Party.

In these complex political tussles, she consistently appealed to morality and truth. In one instance, she countered ten years of media “bashing” by claiming that she had been raised right. Her 2016 acceptance speech for the National Democratic Party candidacy centred on “what is right” for the “people”.

My interview with her and other primary sources point to the influence of the calm, ethical and non-ideological pragmatism of Agyeman-Rawlings’ father, J.O.T. Agyeman, in her appeal to morality. Her father was a technocrat who was connected to Ghanaians belonging to different sides of Ghana’s two main political traditions, the Nkrumahist and the Danquah-Busia traditions. According to Agyeman-Rawlings, her parents’ home was a space for “spirited” conversations shaped by her father’s emphasis on logical and ethical argumentation rather than parochial political interests. This suggests that examining African first ladies merely in relation to their husbands’ politics, however crucial, would be a limited view.

Disrupting the archive

Agyeman-Rawlings wrote a memoir, unusually for a Ghanaian woman politician. As the historian Jean Allman suggests, there is a connection between the erasure of women in Ghanaian politics and the absence of autobiographical writings by nationalist women. My studies argue that Agyeman-Rawlings’ narrative (though incomplete) should be read as a rhetorical disruption of the postcolonial archives. These archives tend to erase or subordinate women’s contributions within a dominant masculine framing of the nation-state.

Agyeman-Rawlings is not the only woman to have laboured for the nation-state. Other women like pro-independence activist Hannah Kudjoe who were involved in similar social welfare activities have been written out of Ghanaian history. Agyeman-Rawlings understood that despite her extensive work, words still mattered if she was to be remembered.

By asserting that “it takes a woman” to “birth” the strength and future of a nation, she boldly inserts a feminine voice into a postcolonial national allegory that centres men. By so doing, she demands a rereading of “great men” like Ghana’s first president, Kwame Nkrumah, and Jerry Rawlings. And in the absence of a Jerry Rawlings autobiography, Agyeman-Rawlings’ writing becomes doubly subversive.

Because women have been historically marginalised from the public sphere, a female politician would be scrutinised whether or not she was vocal. Agyeman-Rawlings chose to be visible and outspoken.

The Conversation

Nancy Henaku 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. Nana Konadu Agyeman-Rawlings: the first lady who redefined women’s power in Ghana. – https://theconversation.com/nana-konadu-agyeman-rawlings-the-first-lady-who-redefined-womens-power-in-ghana-269013

Nos ancêtres du Paléolithique savaient fabriquer des outils simples et efficaces

Source: The Conversation – in French – By Evgeniya Osipova, Préhistoire, Université de Perpignan Via Domitia

Archéologue sur le site paléolithique du nord de la mer d’Aral. Étude du matériel. E.A. Osipova

L’industrie lithique – soit l’ensemble des objets en pierre taillée, pierre polie et matériel de mouture – est souvent le seul témoignage de la culture matérielle préhistorique qui nous soit parvenu. Or, nos ancêtres disposaient d’un kit d’outillage en pierre très diversifié : à chaque activité correspondait un outil spécifique, en particulier pour tout ce qui touchait à la recherche de nourriture et la découpe de la viande.


La viande était une source d’alimentation importante pour les humains préhistoriques, depuis les premiers hominidés, Homo habilis (entre 2,4 millions et 1,6 million d’années), jusqu’à l’apparition de notre espèce, Homo sapiens archaïque (il y a 300 000 ans). Pour trouver de la viande, ils pratiquaient le charognage opportuniste avec les animaux carnivores, puis bien plus tard, la chasse sélective et spécialisée des animaux herbivores.

Mais parvenir à dégager de la viande des carcasses d’animaux nécessite de réaliser une séquence de gestes complexes, en utilisant des outils performants. Au Paléolithique inférieur (entre 800 000 et 300 000 ans avant notre ère) et Paléolithique moyen (entre 300 000 ans et 40 000 ans), il s’agissait d’outils de découpe : des couteaux ou d’autres outils utilisés comme tels. Au fil du temps et en fonction des sites, certains outils travaillés sur deux faces sont devenus de véritables marqueurs culturels. Il s’agit d’abord des bifaces, ces « outils à tout faire » en pierre taillée, qui sont traditionnellement attribués à la culture acheuléenne (entre 700 000 et 200 000 ans en Europe).

Ce sont ensuite des couteaux à dos – le dos correspondant à une partie du bord de la pièce, aménagée ou naturelle, non tranchante et opposée au bord actif, souvent tranchant – autrement appelés des Keilmesser, qui sont typiques de la culture micoquienne (entre 130 000 et 50 000 ans).

Outils de découpe

Les bifaces sont omniprésents en Eurasie, tandis que les couteaux à dos sont majoritairement concentrés en Europe centrale et orientale, dans le Caucase, dans la plaine d’Europe orientale. Les deux catégories d’outils, souvent utilisés pour plusieurs activités, ont en commun une fonction de découpe.

La partie de l’objet qui sert aux pratiques de boucherie est dotée d’un bord suffisamment tranchant et plus ou moins aigu. La fonction de découpe peut être assurée par des éclats simples non aménagés (c’est-à-dire non travaillés par la main humaine) qui ont souvent un bord assez coupant.

La réalisation de ces outils sophistiqués nécessite à la fois de se procurer les matières premières adaptées et d’avoir des compétences avancées en taille de pierre. Mais nos ancêtres avaient-ils vraiment besoin d’outils aussi complexes et polyfonctionnels pour traiter les carcasses d’animaux ? Existait-il d’autres solutions pour obtenir un outil de découpe aussi efficace ?

Notre étude de la période paléolithique à partir d’outils trouvés en Asie centrale, au Kazakhstan, répond en partie à cette question.

Fracturation intentionnelle

La fracturation intentionnelle est une technique qui consiste à casser volontairement un outil en pierre par un choc mécanique contrôlé fait à un endroit précis. Cette technique a été abordée pour la première fois dans les années 1930 par le préhistorien belge Louis Siret. Elle était utilisée au cours de la Préhistoire et de la Protohistoire pour fabriquer des outils spécifiques : burins et microburins, racloirs, grattoirs… La fracture intentionnelle détermine la forme de l’outil en fonction de l’idée de celui qui le taille.

Mais les pièces fracturées sont souvent exclues des études, car la fracture est généralement considérée comme un accident de taille, qui rend la pièce incomplète. Néanmoins, la fracture intentionnelle se distingue d’un accident de taille par la présence du point d’impact du coup de percuteur, qui a provoqué une onde de choc contrôlée, tantôt sur une face, tantôt sur les deux.

À travers l’étude d’une série de 216 pièces en grès quartzite (soit le tiers d’une collection provenant de huit sites de la région Nord de la mer d’Aral), nous avons découvert une alternative simple et efficace aux outils complexes aménagés sur deux faces.

Les objets sélectionnés dans cet échantillon sont uniquement des pierres intentionnellement fracturées. La majorité des pièces présentent un point d’impact laissé par un seul coup de percuteur, porté au milieu de la face la plus plate de l’éclat de grès quartzite. D’autres pièces, plus rares, montrent la même technique, mais avec l’utilisation de l’enclume. La fracture est généralement droite, perpendiculaire aux surfaces de la pierre, ce qui permet d’obtenir une partie plate – un méplat, toujours opposé au bord coupant d’outil.

La création des méplats par fracturation intentionnelle est systématique et répétitive dans cette région du Kazakhstan. Parmi ces outils, on en trouve un qui n’avait encore jamais été mentionné dans les recherches qui y ont été menées : le couteau non retouché à méplat sur éclat, créé par fracture intentionnelle. Cette catégorie de méplat correspond à une fracture longue et longitudinale, parallèle au bord coupant d’un éclat de pierre.

La fabrication de cet outil peu élaboré et pourtant aussi efficace que le biface et le Keilmesser pour la découpe de la viande prend peu de temps et nécessite moins de gestes techniques. C’est pourquoi ils sont abondants et standardisés dans la collection étudiée.

Avec le biface et le Keilmesser, le couteau à méplat sur éclat pourrait ainsi être le troisième outil de découpe du Paléolithique ancien, utilisé dans la région de la mer d’Aral. Les recherches à venir permettront de mieux comprendre le comportement gastronomique de nos ancêtres et d’en savoir plus sur leurs kits de « couverts » en pierre.

The Conversation

Cette recherche a été financée par une subvention du Comité de la Science du Ministère de la Science et de l’Enseignement supérieur de la République du Kazakhstan (Projet N° AP22788840 « Études archéologiques des sites paléolithiques de la région Est de la Mer d’Aral »).

Rimma Aminova, Saule Rakhimzhanova et Yslam Kurmaniyazov ne travaillent pas, ne conseillent pas, ne possèdent pas de parts, ne reçoivent pas de fonds d’une organisation qui pourrait tirer profit de cet article, et n’ont déclaré aucune autre affiliation que leur poste universitaire.

ref. Nos ancêtres du Paléolithique savaient fabriquer des outils simples et efficaces – https://theconversation.com/nos-ancetres-du-paleolithique-savaient-fabriquer-des-outils-simples-et-efficaces-263352