Arrowhead points found in Central Asia could prove the presence of ‘Homo sapiens’ 80,000 years ago

Source: The Conversation – France – By Hugues Plisson, archéologue spécialisé en tracéologie (reconstitution de la fonction des outils préhistoriques par l’analyse de leurs usures), Université de Bordeaux

Obi-Rakhmat rock shelter in Uzbekistan, micro-point hafting and main game hunted around the site 80,000 years ago (artwork courtesy of Malvina Baumann). Malvina Baumann, Fourni par l’auteur

Unretouched triangular microlithic projectile points have been identified from their impact traces in the oldest occupation layers of the Obi-Rakhmat site in Uzbekistan, dating to 80,000 years ago. Their size corresponds to small arrowheads, which are directly comparable to those produced by Homo sapiens during an incursion into Neanderthal territory in the Rhône Valley, 25,000 years later. This new study, published in PLOS One journal, provides a strong argument that could rewrite history on Homo sapiens‘ first settlement in Europe.

The chrono-cultural and anthropological frameworks of prehistory, along with the evolutionary models they inspired, were first created in Western Europe, especially France, in the second half of the 19th century. They were initially linear and Eurocentric: Cro-Magnons (European early modern humans), descending from Neanderthals, laid the foundations for the civilisational superiority claimed by this part of the world at the time. It was not until a century later that the African origin of Homo sapiens, as well as the technological and social features that characterised the Western Upper Palaeolithic (symbolic productions, long-distance networks, and diversified lithic and bone tools and weapons), were recognised.

The earliest evidence of Homo sapiens in Australia, dating back around 65,000 years (Clarkson et al., 2017), predates that found in Europe by 10 millennia, while the ways in which our ancestors initially colonised Western Eurasia over 45,000 years ago remain contentious. The temporal alignment of the earliest European Upper Palaeolithic settlements with those in the Levant, which are considered the closest in terms of typology and technology, is still not satisfactory. This is either because the Levantine data comes from old excavations or because it does not fit into the supposed direct lineage. Despite its geographical proximity to Africa, the origins of the Initial Upper Palaeolithic in the Levant are themselves uncertain. This is why the possibility of a Central Asian origin suggested by archaeologist Ludovic Slimak in 2023 (Slimak, 2023) deserves attention.

A site in Central Asia

View from the Obi-Rakhmat rock shelter on the end of the Tien Shan. Hugues Plisson.
Fourni par l’auteur

Depending on climatic conditions, Central Asia has served as a corridor facilitating movement between the western and eastern parts of the continent or as a refuge zone. The archaeological record in this region is limited but includes several significant Palaeolithic sites.

Among them is the Obi-Rakhmat rock shelter in Uzbekistan, discovered in 1962, whose latest excavation campaigns were led by Andrei Krivoshapkin. At the south-western end of the Talassky Alatau range of the Tien Shan mountains, at an altitude of 1,250 metres, the settlement provides a remarkably consistent lithic industry, comprising points, large blades, and bladelets across a stratigraphic sequence spanning over 10 metres, dating from approximately 80,000 to 40,000 years ago. This industry was initially classified as part of the Initial Upper Palaeolithic but it appears to derive from the Levantine Early Middle Palaeolithic. The early Middle Palaeolithic, associated with archaic Homo sapiens at the Misliya cave (Hershkovitz et al., 2018), disappeared from the Near East around 100,000 years ago. At Obi-Rakhmat, the skull remains of a child found in a layer dating back ~70,000 years show features considered to be Neanderthal and others to be anatomically modern, a combination that could be the result of hybridisation.

Massive blades but microlithic points

Elements of lithic industry from layer 21 at Obi-Rakhmat: unretouched blades (1-2), large retouched blade (3), pointed retouched blades (4-5), impacted retouched points (6-8), unretouched Levallois micro-point (9), unretouched impacted micro-points (10-11). Hugues Plisson.
Fourni par l’auteur

In this context, our international multidisciplinary team has identified tiny, unretouched, triangular projectile points within the lithic debris of the oldest stratigraphic layers. These points were distinguished based on their macroscopic and microscopic impact marks, which were compared to experimental reference data. Due to their small size (less than 2 cm in width and weighing only a few grams) and brittleness, they would have been unsuitable for mounting on heavy shafts. The width of their cutting edges corresponds to the diameter of arrow shafts documented ethnographically for low-poundage bows, consistent with transcultural invariants rooted in physical and ballistic constraints.

Two unretouched micro-points recovered from layer 21 of Obi-Rakhmat. One is intact, while the other is broken and shows scratches resulting from use as a projectile head. The matchstick illustrates their small size.
Fourni par l’auteur

A question of ballistics

Thrown piercing weapons are complex systems whose components are not interchangeable from one type of weapon to another, as they meet different requirements in terms of intensity and nature of stress.

The significant impact force of spears held or thrown by hand makes the robustness of the weapon an essential parameter, both in terms of effectiveness and the hunter’s survival, with mass ensuring robustness, impact force and penetration. In contrast, the penetration of light projectiles shot from a long distance depends on their sharpness, because their kinetic energy, which is much lower, comes mainly from their speed, which, unlike mass, decreases very rapidly along the trajectory and in the target. As this speed cannot be achieved by the extension of the human arm alone, it necessarily depends on the use of a throwing instrument. Arrowheads and spearheads or javelin heads are therefore not designed according to the same criteria and cannot be mounted on the same shafts, the dimensions and degree of elasticity of which are also essential in terms of ballistics. Thus, as in palaeontology, where the shape of a tooth reveals the type of diet and suggests the mode of locomotion, the characteristics of a point provide clues as to the type of weapon of which it is the wounding element.

Weaponry specific to ‘Sapiens’?

The tiny size of Obi-Rakhmat’s points cannot be regarded as a default choice, not only because there is no shortage of good-quality lithic raw material on site from which large blades were made, but microscopic examination of traces of use or wear also shows that within this same assemblage there are also much more robust retouched points (15 to 20 times heavier and 3 to 4 times thicker), similarly impacted by use as axial projectile points (the size of spearheads or javelin heads).

Returning to the bibliography and our own work on Middle Palaeolithic tools (Plisson et Beyries, 1998), we found that the presence in the same assemblage of various types of projectile points and inserts, some of which were microlithic and produced for this purpose, is only known at Homo sapiens sites. The oldest documented occurrences are in South Africa in the Pre-Still Bay (more than 77,000 years old) and later cultural layers of the Sibudu cave. In contrast, lithic points damaged by use as projectile heads are rare in the Neanderthal record. When present, they tend to be large and do not notably differ in size, manufacture or type from points used for activities other than hunting, such as gathering plants or butchery. This difference in the design of tools and weapons takes on anthropological significance.

Levallois points from the Um El Tlel site in Syria, from the Late Middle Palaeolithic period in the Levant attributed to Neanderthals. From left to right: graphic reconstruction based on a fragment found embedded in a donkey vertebra, plant knife blade, butcher knife blade. These multipurpose points are 2 to 3 times wider than the micro-points from Obi-Rakhmat. Hugues Plisson.
Fourni par l’auteur

Given their respective dates, the distance between South Africa and Central Asia (14,000 km) and the difference in the manufacture of the Obi-Rakhmat and Sibudu weapon heads (unretouched knapped stone points vs. shaped stone points or retouched inserts, shaped bone points), the hypothesis of independent centres of invention is the most likely.

From the foothills of the Tien Shan to the Rhône Valley 25,000 years later

The micro-points from Obi-Rakhmat have no known equivalents in the Eurasian Middle Palaeolithic, except for identical projectile points identified by Traceology expert Laure Metz (Lewis et al., 2023) at the Mandrin site, in the Rhône Valley, France, in a layer dating to approximately 54,000 years ago – some ten thousand years before the disappearance of local Neanderthals. Notably, a Homo sapiens milk tooth was also recovered from this layer (Zanolli et al., 2022. The similarity between the micro-points from Obi-Rakhmat and Mandrin, despite being separated by more than 6,000 km and 25 millennia, is such that they could be interchanged without any detail other than the stone betraying the substitution.

Morphological and functional similarity between the micro-points of Obi-Rakhmat and Mandrin, broken by their use as projectile head. The location and extent of their fracture (highlighted in red and blue and macroscopic detail) are indicative of axial impact. Hugues Plisson.
Fourni par l’auteur

Recent work published by paleogeneticists Leonardo Vallini (Vallini et al., 2024) and Stéphane Mazières (Mazières et al., 2025) defines the Persian Plateau, on the north-eastern edge of which Obi-Rakhmat is located, as a population hub where the ancestors of all present-day non-Africans lived between the early phases of expansion out of Africa – long before the Upper Palaeolithic – and the wider colonisation of Eurasia. This resource-rich environment may have provided a refuge conducive to demographic regeneration after the genetic bottleneck of the exit from Africa, interaction between groups and, consequently, technical innovations.

On either side of the Persian plateau (orange box), genetically identified as a refuge area for the concentration and demographic development of first Homo sapiens who left Africa, Obi-Rakhmat and Mandrin share the same micro-projectile points, 25,000 years and 6,000 km apart. Hugues Plisson.
Fourni par l’auteur

Obi-Rakhmat and Mandrin may represent two geographical and temporal milestones within the same process of dispersal, as suggested by Ludovic Slimak (Slimak, 2023), characterised by the dissemination of a key technological innovation unique to Homo sapiens. So far unnoticed because they are unretouched, tiny and fragmentary, it is likely that the micro-projectile points for which recognition criteria have now been defined will begin to appear at sites between Central Asia and the western Mediterranean.

Premises for a new scenario of the western peopling by ‘Homo sapiens’

This discovery is stimulating in several ways.

It validates the consistency of the research conducted at the Mandrin site, which came to the conclusion that Sapiens armed with bows made a brief incursion into Neanderthal territory. Several elements of this study had been criticised (Klaric et al., 2024)– which is, however, normal in science when a new proposal deviates too far from established knowledge – but its predictive dimension had not been considered at the time.

The similarity between Mandrin and Obi-Rakhmat’s micro-points cannot be a mere coincidence. It is not only their shape that is similar, but also the way they are made, which requires real expertise, as evidenced by the meticulous preparation of their striking platform and their function. One could debate the appropriate instrument for shooting arrows armed with such tiny tips, the bow being in filigree, or whether it is preferable to remain cautious and speak only of shooting, but this already contrasts with what we know about Neanderthal hunting weapons and their design.

Another remarkable aspect, which is still relatively uncommon, is the convergence and complementarity of data from material culture and from our genetic memory, which did not influence each other given the dates of the respective studies and publications. Together, they sketch out a rewriting of the scenario of Homo sapiens’ arrival in Europe: it was thought that he came directly from Africa by the shortest route 45,000 years ago, but we now discover that he had been established in the heart of the Eurasian continent for a long time, well before expanding in search of more territories.


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The Conversation

Les auteurs 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 organisme de recherche.

ref. Arrowhead points found in Central Asia could prove the presence of ‘Homo sapiens’ 80,000 years ago – https://theconversation.com/arrowhead-points-found-in-central-asia-could-prove-the-presence-of-homo-sapiens-80-000-years-ago-276550

AI and 3D printing help researchers create heat- and pressure-resistant materials for aerospace and defense applications

Source: The Conversation – USA – By Houlong Zhuang, Associate Professor of Engineering, Arizona State University

Hypersonic aircraft, like NASA’s X-43A shown here, are exposed to extreme heat and pressure. Jim Ross/NASA via Getty Images

From hypersonic aircraft to nuclear-powered submarines, many of today’s most advanced defense systems rely on a special class of materials known as refractory alloys. This class refers to metals that do not melt or weaken easily, even in extreme heat.

An alloy is a material made by combining two or more metallic elements to achieve properties no single metal can offer on its own – greater strength, for example, or better resistance to corrosion. Refractory alloys are based on elements such as tungsten, niobium and molybdenum, which have some of the highest melting points of any metals.

Their atoms are held together by strong chemical bonds and arranged in a stable crystal structure that resists deforming, even at extreme temperatures. Where conventional alloys begin to soften and slowly deform under constant stress, refractory alloys retain their strength, making them essential for components exposed to extreme heat, stress and radiation.

Most refractory alloys in service today were designed decades ago. They predate modern 3D printing of metal parts, also called additive manufacturing, and artificial intelligence.

To execute metal 3D printing, a laser or electron beam melts successive thin layers of metal powder.

This builds up a 3D part directly from a computer model by adding material layer by layer, rather than using molds or removing material from a solid block. 3D printing allows shapes that are impossible with traditional manufacturing methods. However, many current refractory alloys are difficult or impossible to manufacture reliably using these techniques.

This mismatch can slow the domestic production of new parts. To help address these manufacturing and supply-chain challenges, our team of materials researchers at Arizona State University and UNSW Sydney has formed a new international collaboration to redesign high-temperature alloys.

Old alloys in a new manufacturing world

Additive manufacturing allows defense and aerospace manufacturers to produce complex components locally, on demand and with far less material waste. In principle, it is ideal for producing replacement parts for aircraft, spacecraft and naval systems.

In practice, many refractory alloys crack, warp or develop internal defects when 3D-printed. Their compositions were optimized for casting or forging, not for the rapid melting and solidification involved in laser-based printing. In 3D printing, a laser melts and resolidifies metal thousands of times in quick succession, creating steep temperature gradients that generate enormous internal stresses. Several key refractory metals are brittle at room temperature and cannot absorb those stresses without cracking.

The inside of a 3D printer where a piece deposits a thin stream of material onto a round part.
3D printers deposit thin layers of material on top of each other until they build up the part based on the design.
brightstars/Photographer’s Choice RF via Getty Images

Redesigning these alloys using traditional trial-and-error methods would take decades.

Teaching computers to design new metals

Our alternative approach uses reinforcement learning, a form of artificial intelligence best known for training computers to master games such as Go or chess.

Designing a new alloy is a bit like mixing ingredients for a recipe, but at the atomic level. Instead of planning moves on a board, the AI system explores thousands of possible alloy recipes – for example, different combinations of chemical elements. Even tiny changes in the ingredients can completely change how the final material behaves.

The AI evaluates each candidate virtually against multiple criteria, including strength at temperatures above 1,800 degrees Fahrenheit (1,000 degrees Celsius) and resistance to damage caused by reacting with oxygen at high heat, as well as weight, cost and, crucially, whether it can be reliably 3D-printed.

A diagram showing AI leaning to 3D printing, then testing and analysis, then next-generation materials
The research team uses reinforcement learning to figure out combinations of metals to create alloys, then uses 3D printing to manufacture parts with less waste than traditional methods.
Vitor Rielli

Alloys that should perform well are rewarded, while those that fail are discarded. Over repeated cycles, the system learns which chemical combinations work best.

We can then manufacture and test the most promising AI-designed alloys in the laboratory. Their real-world performance feeds back into the model, steadily improving its predictions.

Strategic benefits beyond the laboratory

The implications of our research extend beyond the lab.

For defense agencies, faster materials development means quicker deployment for next-generation engines, hypersonic vehicles and systems that protect against heat. AI-designed alloys can be optimized for strength, heat resistance and manufacturability. For example, NASA’s GRX-810 alloy, designed with computational methods and 3D-printed, is 1,000 times more durable at high temperatures compared with traditional alloys.

Traditional manufacturing of refractory metals wastes up to 95% of the raw material through machining – removing unwanted material to create the precise shape – but 3D printing can bring that figure close to zero.

Our work is an international collaboration. At Arizona State University, the focus is on AI-driven computational design. UNSW Sydney’s facilities allow for high-temperature testing by looking at the metal’s microstructure and conducting additive manufacturing under realistic conditions.

Researchers use AI to design materials that can function under extreme heat and pressure.

Challenges still ahead

This approach is not without hurdles. One of the biggest is data scarcity: AI models learn from existing experimental results, and for refractory alloys, that data is limited. Far fewer alloys in this class have been systematically tested, compared with more common materials like steel or aluminum.

There are also practical constraints. Refractory metal powders suitable for 3D printing are expensive and difficult to source, and scaling up from small laboratory samples to full-sized components is difficult. An alloy that performs well as a thumbnail-sized test sample may behave very differently when printed as a large, complex part.

Finally, AI predictions must always be validated experimentally – and those experiments are costly and time-consuming. The system does not eliminate the need for rigorous physical testing.

A new model for defense-focused research

Our collaboration is in its early stages. We are currently building the AI model and assembling the experimental databases it will learn from. Later this year, the first candidate alloy compositions will be selected for 3D printing and laboratory testing. The results will feed back into the model.

We are also working with defense research agencies to ensure our work aligns with real-world needs and to lay the groundwork for larger-scale programs.

In an era where technological advantage increasingly depends on speed and adaptability, reimagining how we design the metals behind defense systems can improve the systems themselves.

The Conversation

Houlong Zhuang receives funding from Security and Defence PluS Alliance.

Vitor Rielli receives funding from Security and Defence PluS Alliance

ref. AI and 3D printing help researchers create heat- and pressure-resistant materials for aerospace and defense applications – https://theconversation.com/ai-and-3d-printing-help-researchers-create-heat-and-pressure-resistant-materials-for-aerospace-and-defense-applications-273687

With Artemis II facing delays, NASA announces big structural changes to the lunar program

Source: The Conversation – USA – By Marcos Fernandez Tous, Assistant Professor of Space Studies, University of North Dakota

Top NASA officials give an update on major changes to the Artemis program on Feb. 27, 2026. Miguel J Rodriguez Carrillo/AFP via Getty Image

Throughout February 2026, people at the Kennedy Space Center got to witness an exciting sight: NASA’s behemoth Space Launch System rocket, SLS, standing on the launch pad, aimed toward the sky. The launch system has been key to the Artemis program – an ambitious series of missions intended to culminate in a sustained human presence on the Moon. NASA had initially planned to launch the second Artemis mission, which would take a crew of four people around the Moon, in February.

But as anticipation for launch built, an issue with the liquid propellant arose. A few days later, the SLS faced another problem, this time with the rocket’s upper stage, and had to roll back from the pad.

I’m an aerospace expert who is deeply passionate about aerospace technology and what it means for the U.S. and humanity’s future. I’ve been following the Artemis program’s timeline – February 2026 has represented a pivotal moment for U.S. spaceflight. Artemis II faced a number of delays, and NASA officials announced a shake-up of the larger program’s timeline.

A rocket attached to scaffolding on a rolling pad, against a sunset.
NASA’s Artemis II SLS Moon rocket, along with the Orion spacecraft, slowly rolls back toward the vehicle assembly building at the Kennedy Space Center on Feb. 25, 2026.
AP Photo/John Raoux

Springing leaks

It started on Feb. 2, during Artemis II’s first wet dress rehearsal. During this major test, engineers assemble all components of the Space Launch System and fill its tanks with a combined 700,000 gallons of super-cold liquid hydrogen and liquid oxygen. These liquids act as the propellant for the rocket during launch.

During the test, the team detected a hydrogen leak at the interface of a 33‑foot-high (10 meters) service mast, the removable structure that brings the hydrogen and oxygen to the tank. They attributed the cause of the issue to moisture accumulated in the Teflon seal of two interfaces between that mast and the vehicle’s tank.

On the following day, NASA decided to postpone the launch until March 6. A new wet dress rehearsal would take place on Feb. 19 to verify everything was working as expected.

On the day of the second wet dress rehearsal, hydrogen operations proceeded smoothly, seemingly confirming plans for a March launch for Artemis II. Engineers at NASA likely breathed a sigh of relief, but they did so too early. A couple of days later another problem surfaced: They found the exploration upper stage was leaking helium. This upper stage of the rocket kicks in above 62 miles (100 kilometers), once the core stage expends all its propellant.

Because helium is essential for pressurizing cryogenic tanks and for purging the pipelines that will carry highly reactive liquid oxygen, the leak raised concerns.

Notably, these issues echoed the challenges SLS encountered ahead of its first launch for the Artemis I mission in 2022. Artemis I launched nearly six years after NASA’s original target date, ultimately accumulating 25 scrubbed or delayed launch attempts. Recurring hydrogen leaks in the tail service mast umbilical – a very similar issue – caused several of these delays.

Trouble with the SLS

On Feb. 25, the same day SLS rolled back to the vehicle assembly building for more work, NASA’s independent Aerospace Safety Advisory Panel released its annual report. This panel began in the aftermath of the January 1967 Apollo command module fire that claimed the lives of three astronauts, and NASA headquarters takes its assessments very seriously.

Citing the problems encountered on Artemis I and II, the panel warned of elevated risks for Artemis III, which planned to land on the Moon. They strongly recommended NASA restructure the program to reduce the likelihood of similar issues on future missions.

On Feb. 27, NASA made a major announcement: Artemis IV, scheduled for 2028, would now include a lunar landing. Artemis IV would then overlap with another landing planned in the same year, Artemis V.

NASA head Jared Isaacman discusses changes to the Artemis program on Feb. 27, 2026.

NASA also confirmed that it plans to replace the exploration upper stage – the source of the helium leak – with a different upper stage known as the interim cryogenic propulsion stage. While the exploration upper stage was designed to use four engines, the interim cryogenic propulsion stage relies on a single engine.

The interim cryogenic propulsion stage previously flew on Artemis I, after which NASA intended to transition to the exploration upper stage for future missions. With the restructuring, however, the exploration upper stage program has been canceled, and NASA is returning to the interim cryogenic propulsion stage instead. With this change, Artemis appears to be going back to the basics and returning to simpler, proven hardware.

While Artemis II will not launch before April, the plan for the mission itself remains the same: It will still fly around the Moon.

But this new situation poses a question: If Artemis IV will now carry out the lunar landing, what will become of Artemis III, which had originally been planned as humanity’s return to the Moon? In essence, NASA is accelerating the schedule by adding more launches and tests before the first lunar landing attempt, and these changes are not necessarily to Artemis’ detriment.

A new timeline

NASA aims to increase the cadence of launches up to every 10 months starting in April 2026, incorporating fewer changes from mission to mission each time. This approach reduces technological uncertainty and stands in sharp contrast to the more than three‑year gap between the 2022 launch of Artemis I and the potential 2026 launch of Artemis II.

Artemis III will now become a tightly focused rehearsal mission lasting 30 days. NASA will test each mission component independently rather than checking them all together as a unit. Instead of visiting the Moon, Artemis III will remain closer to Earth.

NASA Administrator Jared Isaacman explained to CBS on Feb. 27 that Artemis III will launch the Orion spacecraft, which holds the astronaut crew, into low Earth orbit, where it will dock with one or both lunar landers – Blue Origin’s Blue Moon lander and SpaceX’s Human Landing System.

Jeff Bezos stands in front of a large spacecraft lander labeled 'Blue Moon'
Jeff Bezos, founder of Blue Origin, introduces its newly developed lunar lander Blue Moon.
Jonathan Newton/The Washington Post via Getty Images

The Human Landing System will be a modified version of SpaceX’s Starship, the company’s enormous, superheavy spacecraft. The docking maneuver will help NASA confirm that the lander can handle the forces involved in connecting with Orion in space – essentially checking that the structure behaves as expected and can safely support the crew and their equipment.

Isaacman also pointed out that Artemis III may allow for NASA to test out the new spacesuit Axiom Space is designing for forays outside of the spacecraft.

The mission may also test navigation, communication, propulsion and life‑support systems. Interestingly, this series of tests aligns Artemis III more closely with the historical role of Apollo 7, which focused on evaluating the command and service module in Earth orbit.

In short, the new plans reshape Artemis III into a proof‑of‑concept mission intended to validate several critical systems before the two lunar landings planned for 2028 with Artemis IV and V. If successful, this approach should greatly improve the reliability of the missions that will finally return humans to the lunar surface. The revised timeline creates more opportunities to test and troubleshoot all the systems required for a safe landing.

It will also keep the missions more straightforward. With the same configuration across all missions, the tests will build on each other.

For now, you will need to wait a bit longer to watch humans walk in the Moon’s south pole region, where icy craters may hold clues to the early history of our solar system. But if February 2026 sets the tone, this next chapter will be anything but dull. Fasten your seat belts.

The Conversation

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

ref. With Artemis II facing delays, NASA announces big structural changes to the lunar program – https://theconversation.com/with-artemis-ii-facing-delays-nasa-announces-big-structural-changes-to-the-lunar-program-277169

I study why zebrafish larva prefer to circle left or right, to understand how and why human brains encode right- and left-handedness

Source: The Conversation – USA – By Eric Horstick, Associate Professor of Biology, West Virginia University

Having a hand preference speaks to more than just your preferred way to write. Domingo/iStock via Getty Images Plus

Being right- or left-handed is a familiar fact about yourself you likely don’t think about much on a day-to-day basis. However, your handedness affects how you interact with the world.

For many people, it determines how they brush their teeth, use tools, play sports, write, eat and much more. Simply try to enjoy a bowl of soup or sign your name with your nondominant hand to appreciate the impact a hand preference can have on your daily life.

Interestingly, this behavioral asymmetry is not unique to humans. Preferences for using the right or left hand, paw or eye exist in most species. For example, many primate species have individual left- or right-hand preferences for manual tasks. Similarly, different bird species have varying eye preferences for distinct visual tasks. Even the largest animal alive, the blue whale, shows a preference for the direction of its rolls during feeding. This inherent and often-overlooked feature of behavioral asymmetry is a widespread phenomenon in the animal kingdom.

The universality of behavioral asymmetry suggests that having an assigned hand, eye or other preference is beneficial. But depending on one hand for so many important tasks means that a single injury could be devastating. This paradox poses an important question: Why would having handedness be better for survival than not?

Insights from fish ‘handedness’

To address this question, scientists have tried to understand the genetics of handedness. While large-scale genetic studies in humans have identified dozens of genes associated with handedness, researchers also found that genetics alone only partially accounts for whether someone is left- or right-handed. This means behavioral asymmetry like handedness is likely the product of complex interactions between genetics, development and the environment.

For the past six years, my research lab has been interested in understanding behavioral asymmetry and how such behaviors get encoded in the brain. We primarily use larval zebrafish to explore the neural basis of behavioral asymmetry. These animals have transparent bodies and rapidly develop into adults in just a few days, making them ideal models to study. Additionally, the genetics and brain structure of zebrafish are highly similar to those of humans.

Fish have a form of handedness called motor asymmetry, which involves sustained periods of turning in the same direction. I had previously found that when light was cut off, larval zebrafish start circling in a leftward or rightward direction, sometimes for up to a minute or more. The fish would continue to preferentially turn in that same direction over the course of hours, days and even weeks, looking for a light source. This meant that vision drove their motor asymmetry.

Microscopy image of violet, symmetrical outline of the top of a fish with two white lines and nodules extending down its length
Zebrafish make it easy to see their neural activity. Eyes are to the left, and neurons are colored white.
National Institute on Deafness and Other Communication Disorders/Flickr, CC BY-NC-SA

Students in my lab recorded the zebrafish’s neural activity in response to loss of environment light – the trigger for motor asymmetry. They found a subset of approximately 60 neurons in the thalamus – a region of the brain that is evolutionarily conserved among vertebrates and involved in relaying sensory information – was functionally linked to motor asymmetry. Removing these neurons eliminated this motor asymmetry, suggesting a potential neural basis for where behavioral asymmetry is established in the fish brain.

When my lab repeated our experiments on five additional species of larval fish from around the world, we found similar motor asymmetry in response to light. Much like handedness in primates, it appears that handedness in fish is likely more of a rule than an exception.

However, we did find one exemption: the Mexican tetra, also known as cavefish. These animals are found in perpetually dark cave environments and are naturally blind. In collaboration with our colleagues at the Duboué Lab at Florida Atlantic University, we found that these animals showed no motor asymmetry.

These findings suggest that the universal nature of behavioral asymmetries are likely crucial responses to common challenges that different organisms encounter.

Behavioral asymmetry may solve challenges

Hurting your dominant hand does more than just ruin your softball or ultimate frisbee game. Handedness is associated with broad neural asymmetries in the brain that are linked to performance in language comprehension and working memory tasks. In addition, having atypical handedness – such as preferring different hands for different activities – is associated with a range of neurological conditions, including autism and attention-deficit/hyperactivity disorder.

Understanding why animals have behavioral asymmetries offers clues about how the environment influences broader cognitive function. If environmental challenges indeed drive handed behaviors, what problems does motor asymmetry solve for fish?

Close-up of a silver fish looking up at a pink-tinged fish without eyes
Astyanax mexicanus living on the surface have eyes (bottom), while those living in caves do not (top).
Daniel Castranova/NICHD/NIH via Flickr, CC BY-NC-ND

In nature, animals often circle when searching for something, such as a food source. For larval zebrafish, light is an important resource for their ability to see and capture prey. When we placed a light source at varying locations around them, the larval zebrafish start circling to quickly navigate into illuminated environments conducive to hunting. Based on our work, we hypothesize that the asymmetries in fish that allow them to search more efficiently work in parallel ways to those of other animals, like eye movement in birds or language comprehension in people.

Prior research has suggested that brain asymmetries improve cognitive performance by reducing competition between the two sides of the brain. Our work supports these hypotheses by showing how, for zebrafish, motor asymmetry provides a default response to find light and efficiently catch a needed snack.

With a helping hand from fish handedness, researchers are getting a clearer idea of the universality of behavioral asymmetry and how the environment may be shaping the brain so that one hand, or fin, provides an advantage in daily life.

The Conversation

Eric Horstick receives funding from the National Institutes of Health and National Science Foundation.

ref. I study why zebrafish larva prefer to circle left or right, to understand how and why human brains encode right- and left-handedness – https://theconversation.com/i-study-why-zebrafish-larva-prefer-to-circle-left-or-right-to-understand-how-and-why-human-brains-encode-right-and-left-handedness-274578

Why the U.S. is unlikely to curtail China’s critical minerals dominance

Source: The Conversation – Canada – By Craig Anthony Johnson, Professor of Politics, University of Guelph

The United States government recently hosted a critical minerals summit aimed at reducing China’s predominant role in the global production of smartphones, weapons systems, lithium-ion batteries and electric vehicles (EVs).

The meeting, which included representatives from Argentina, Australia, Bolivia, Canada, Chile, the Democratic Republic of Congo, India, the European Union, Japan, South Korea and the United Kingdom, is part of a larger structural trend that Canadian Prime Minister Mark Carney recently called a “rupture” to the rules-based international order.

At first glance, the U.S. government’s weaponization of tariffs and trade indicate changing dynamics in global trade and the development of critical minerals, advanced manufacturing and emerging technologies. On closer inspection, American efforts to weaken China’s dominance over the critical minerals industry face a more complicated reality and an intricate web of public- and private-sector investment agreements tied to Chinese firms.

According to the International Energy Agency, China accounts for more than 80 per cent of global battery production. The figure jumps to 90 per cent for grid scale batteries that are used to store wind and solar power.

Global battery sales have grown sixfold since 2020, a direct result of falling prices and the competitiveness of China’s low-cost manufacturing model. Over the same period, manufacturing of grid-scale battery systems has expanded 20-fold.

Within this reality, the idea that the U.S. can strategically reduce China’s role in the production and processing of critical minerals appears highly unlikely.

Competition for critical minerals

My research focuses on environmental politics, extractive industries and the expansion of renewable energy value chains in Latin America. I am currently leading a study on the politics of lithium extraction in Argentina, Australia, Bolivia, Canada and Chile.

Over the past year, the U.S. upped its efforts to reduce China’s involvement in South America, a region that accounts for more than 50 per cent of the world’s known lithium deposits.

In 2025, the U.S. government acquired a five per cent share in Lithium Americas, a Canada-based company that has a long presence in Argentina. In February, the U.S. government announced another deal to acquire a 10 per cent stake in the mining company USA Rare Earth.

In 2025, the White House used the threat of tariffs and a US$20 billion bailout package to negotiate a new trade agreement with Argentina. Meanwhile, the U.S.-dominated Inter-American Development Bank signed an agreement to provide more than US$140 million to improve critical mineral production and processing capacity in Latin America.

However, decoupling China from regional production networks raises deeper questions about whether it makes good business or strategic sense to disrupt a global production network that produces 80-90 per cent of the world’s lithium-ion batteries.

At a time when the U.S. is pursuing an “America first” policy of onshoring the production and processing of critical minerals, China has used joint ventures and public-private partnerships to secure access while offshoring the dirtier parts of critical minerals production.

The Chinese company Ganfeng Lithium has been active in Argentina for about a decade and is currently expanding its presence through joint ventures.

In August 2025, the company signed joint ventures with Canadian company Lithium Americas, expanding its operations in the salt flats of Pozuelos, Pastos Grandes and Cauchari-Olaroz. The vast majority of Ganfeng’s production goes to battery and EV assembly hubs in China and Southeast Asia.

In contrast, China’s involvement in Chile has largely been limited to a minority share in the Chilean mining company SQM since 2018. Under the left-wing government of Gabriel Boric, Chile’s National Lithium Strategy promised to restrict new licences to state-owned copper and mining companies Codelco and Enami.

However, the recent electoral victory of President-elect José Antonio Kast, a right-wing politician with close ties to Chile’s business sector, raises new questions about the future viability of the nationalist policy.

Similarly, questions have been raised about whether the Bolivian government will maintain its state-led model of resource nationalism under the newly elected right-wing government of Rodrigo Paz Pereira.

Chinese and Russian companies have a strong presence in Bolivia. In 2024, the majority state-owned lithium company, YLB, signed a US$1 billion agreement with the Chinese consortium CBC to start developing the Uyuni salt flat. But Bolivia’s lithium production has remained negligible, reflecting longstanding challenges of extracting lithium from the Uyuni salt flat and resolving domestic conflicts over the distribution of profits.

Looking ahead

In theory, the election of right-wing governments in Argentina, Bolivia and Chile should favour the U.S. This is most evident in Argentina, where libertarian president Javier Milei has already established strong ties with the White House and with U.S. President Donald Trump personally.

Compared with Argentina, Chile appears less likely to concede to American concerns about China. This reflects the Chilean state’s dominant role in the global copper market, domestic conflicts over the nationalization of Chile’s lithium sector and the enduring influence of Chinese political and diplomatic interests.

Looking ahead, major questions remain about whether American companies have the willingness and capacity to assume China’s role in the global production of lithium-ion batteries and whether they’ll align themselves with U.S. foreign policy interests. For instance, the U.S.-based Albemarle Corporation is one of the world’s largest lithium companies, but it is publicly traded and owned by multiple investors.

Outside of South America, global lithium production remains dominated by American, Chinese and Australian firms, including Rio Tinto, the Anglo-Australian mining giant that is currently consolidating lithium operations in Argentina and Chile. Almost all have joint ventures with Tianqi, Ganfeng and other Chinese companies.

The North American economy has neither the capacity nor the wage competitiveness to replace China’s role in producing and processing critical minerals for batteries, energy storage systems and EVs.

Reducing China’s dominant role in the global critical minerals industry would entail developing a robust supply chain that can out-compete China’s. Given current economic and geopolitical realities, this seems improbable in the foreseeable future.

The Conversation

Craig Anthony Johnson receives funding from the Social Sciences and Humanities Research Council of Canada.

ref. Why the U.S. is unlikely to curtail China’s critical minerals dominance – https://theconversation.com/why-the-u-s-is-unlikely-to-curtail-chinas-critical-minerals-dominance-275416

Congress once fought to limit a president’s war powers − more than 50 years later, its successors are less willing to assert their authority

Source: The Conversation – USA – By Sarah Burns, Associate Professor of Political Science, Rochester Institute of Technology; Institute for Humane Studies

Rubble from a police station damaged in airstrikes on March 3, 2026 in Tehran, Iran. Majid Saeedi/Getty Images

Article 1 of the U.S. Constitution gives Congress the power to declare war, not the president. But most modern presidents and their legal counsel have asserted that Article 2 of the Constitution allows the president to use the military in certain situations without prior congressional approval – and have acted on that, sending troops into conflicts from Panama to Libya, with no regard for Congress’ will.

Congress has for the most part registered only feeble and ineffective opposition to such executive action. The current move in Congress to deny President Donald Trump the ability to continue the war with Iran – led by Democrats, but with some Republican support – will likely fail, as have previous efforts during other conflicts.

But there was a time when Americans saw Congress stand up to a president who unilaterally took the country to war.

It was at the tail end of the Vietnam War, when Congress passed the War Powers Resolution of 1973, asserting that it was legislators – not the president – who had the power to declare war.

Once it passed both houses, President Richard Nixon vetoed it, claiming it was unconstitutional.

In response, the legislative branch overturned the veto with the two-thirds majority vote needed to prevail.

Compared to Congress’ limp response to Trump’s actions in Iran, and its similar failure to assert itself during Trump’s military action in Venezuela, it was a breathtaking act of legislative assertion.

A section of text from a Congressional resolution about war powers.
The ‘purpose and policy’ section of the 1973 War Powers Resolution passed by Congress.
National Archives

Congress asserts itself

When they debated the War Powers Resolution, members of Congress were seeing the erosion of their control over the decision to engage in military operations large and small. With a strong bipartisan consensus, they determined they had to collectively use their powers, including the power of the purse, to thwart executive overreach.

Congress’ actions came in response to the growing protests against the Vietnam War in general and Nixon’s decision to expand the war by sending U.S. troops to invade the neutral country of Cambodia to disrupt the supply lines of the Viet Cong, the communist guerrilla force that accounted for a large number of the 58,000 Americans killed in the war.

Nixon had begun covert carpet bombing of Cambodia in 1969, and then announced in 1970 that he would send ground troops into the country the next year.

Congress – and the country– reacted extremely negatively. Members of Congress collaborated across party lines to draft legislation in an attempt to assert their power. It was a slow process, however, involving long periods of deliberation.

A setting sun behind a plume of black smoke rising in the sky.
The sun sets behind a plume of smoke rising after a U.S.-Israeli military strike in Tehran, Iran, on March 3, 2026.
AP Photo/Vahid Salemi

They used many different methods to attempt to constrain the president. Within months of the introduction of troops to Cambodia, Congress attempted to pass amendments that would restrict his ability to invade neighboring countries. Prompted by protesting and the illegal actions in Cambodia, Congress began crafting legislation that would draw down troops in Vietnam.

With these moves, lawmakers placed immense pressure on the president. This eventually led to the drafting and eventual signing of the peace agreement ending the Vietnam war in 1973.

This was not enough for Congress, however.

Rules – and flexibility

Congress wanted to create a document ensuring presidents could not unilaterally make war. They wanted legislative consultation.

They intended the War Powers Resolution to act as a permanent constraint. So, in the resolution they spelled out the specific actions in which presidents can start a conflict:

• First, if there is an invasion of the United States, the president can respond. In this instance, the president can act prior to congressional authorization.

• Second, if Congress provides an “Authorization for the Use of Military Force,” the president can assume he has authorization – but only as long as it is in effect.

• Finally, if Congress declares war, the president can act.

Lawmakers did, however, provide some flexibility. In the War Powers Resolution, they said a president can initiate and carry out hostilities for 60 days and has a further 30 days to draw down the troops. Once the executive has initiated hostilities, Congress must receive information about that action within 48 hours.

This opens the door for presidents to engage in smaller-scale or short operations without stepping outside the lines set in the law.

Presidents from both parties have availed themselves of this flexibility. As far back as 1975, when President Gerald Ford rescued the SS Mayaguez, the merchant ship captured by Cambodia’s Khmer Rouge, presidents have acknowledged the law and dutifully reported their military actions to Congress.

Like his predecessors, Trump sent a letter to Congress after his June 2025 missile attacks against Iran, as well as at the start of the currently open-ended conflict.

An older man in a blue coat and red hat with 'USA' written on it waves.
President Donald Trump after landing aboard Air Force One on March 1, 2026, at Joint Base Andrews, Maryland.
Roberto Schmidt/Getty Images

Presidents since the passage of the War Powers Resolution have not, however, acknowledged that they have to get congressional approval of their actions, with few exceptions. Predominantly, without congressional approval, they limit their actions to the 60-to-90-day window.

President Barack Obama, however, attempted to circumvent the window when his bombing campaign in Libya in 2011 dragged on, as well as when he bombed the Islamic State group in 2014. In the first instance, he claimed the War Powers Resolution did not apply. In the second, he claimed each bombing campaign was discrete, rather than part of a larger campaign.

Exploiting authorizations

The balance of power between the legislative and executive branches changed considerably with the passage of the 2001 Authorization for Use of Military Force related to the Sept. 11, 2001, terrorist attacks, and the 2002 Authorization for Use of Military Force that gave legislative permission for President George W. Bush to invade Iraq.

Because Congress did not put sunset dates into these authorizations, subsequent presidents Obama, Trump and Joe Biden used those same authorizations for a host of later military actions in the Middle East and elsewhere.

And legislators are deeply divided in the current discussions about demanding the cessation of hostilities against Iran.

Republican House Speaker Mike Johnson says that limiting the president at this time is “dangerous.” Former congresswoman Marjorie Taylor Greene – who has fallen out of favor with Trump’s MAGA base and the president himself – took the opposing view, posted on social media, “Now, America is going to be force fed and gas lighted all the ‘noble’ reasons the American ‘Peace’ President and Pro-Peace administration had to go to war once again this year, after being in power for only a year.”

Has the U.S. entered a moment when members of Congress reassert themselves the way they did at the tail end of the Vietnam war?

It is possible that they will follow James Madison’s advice about the power relationship between Congress and the president. Writing in the Federalist Papers, Madison said that “ambition” has “to counter ambition.” He continued, “The interest of the man must be connected with the constitutional rights of the place. It may be a reflection on human nature, that such devices should be necessary to control the abuses of government.”

As I explain in my book about congressional war powers, the constitutional system creates an invitation to struggle. Now, as the U.S. wages war on Iran, Congress must decide whether it wants to struggle, as it did during the Vietnam War, or remain compliant and in the president’s shadow.

The Conversation

Sarah Burns has received funding from the Institute for Humane Studies.

ref. Congress once fought to limit a president’s war powers − more than 50 years later, its successors are less willing to assert their authority – https://theconversation.com/congress-once-fought-to-limit-a-presidents-war-powers-more-than-50-years-later-its-successors-are-less-willing-to-assert-their-authority-277435

Housing First helps people find permanent homes in Detroit − but HUD plans to divert funds to short-term solutions

Source: The Conversation – USA – By Deyanira Nevárez Martínez, Assistant Professor of Urban and Regional Planning, Michigan State University

Detroit area homelessness providers worry the federal funding shift could affect thousands of individuals and families across the region. Charles Ommanney/Getty Images Joshua Lott/Getty Images

A bureaucratic shift in Washington is threatening to undo years of progress in Detroit’s fight against homelessness, potentially forcing thousands of the city’s most fragile residents back onto the streets.

In November 2025, the U.S. Department of Housing and Urban Development revised how it would allocate funding through its flagship homelessness program, the Continuum of Care.

The change reduced the share of funding available for permanent subsidized housing and increased funding for transitional short-term housing.

HUD officials described the shift as a move away from a “housing first” model toward a “treatment first” approach that emphasizes participation in services, such as drug addiction disorder treatment, before or alongside housing placement.

The administration has argued that this promotes self-sufficiency. Critics contend that stable housing is the foundation that makes treatment and recovery possible.

The policy revision has been challenged in court by 20 states, including Michigan, as well as city and county governments and advocacy organizations. They argue it could destabilize individuals and families across the country, state and here in Detroit.

I am an urban and regional planning scholar who studies housing policy, and I serve on the research council of the National Alliance to End Homelessness.

In December 2025, I joined 77 other homelessness researchers who sent a letter to Congress analyzing the likely impacts of HUD’s revised funding approach. That analysis draws on decades of peer-reviewed research evaluating which housing interventions reduce homelessness and which do not.

That same month, a federal judge issued a preliminary injunction that temporarily pauses HUD’s efforts to shift funding away from permanent supportive housing.

HUD officials stated that the agency intends to apply the changes in future funding rounds, once the order is no longer in effect.

Homelessness in Detroit

Detroit’s homelessness crisis is both long-standing and worsening.

The number of people who experience homelessness in Detroit, Hamtramck and Highland Park increased by about 16% from 2023 to 2024, with roughly 1,725 people experiencing homelessness on a single January night, including hundreds of families. Children in particular have been hit hard by this crisis. One data snapshot shows 2,579 children reported being doubled up, staying in a shelter, staying in a hotel or motel or being unsheltered. This was a record number for the Detroit Public Schools Community District.

While permanent supportive housing has strong outcomes for those who receive it, overall homelessness has continued to increase due to rising rents, economic instability and the limited housing supply, which has historically outpaced the number of available supportive units.

Detroit’s homelessness response system is coordinated through the federally funded local Continuum of Care led by the Homeless Action Network of Detroit.

In recent years, Detroit has taken steps to strengthen coordination, expand shelter capacity and increase housing placements. But the system heavily depends on federal funding to provide permanent supportive housing.

What could change in federal homelessness funding

The Continuum of Care program began in 1994 and was later codified in 2009 by the Homeless Emergency Assistance and Rapid Transition to Housing Act. It is the largest federal funding stream dedicated to addressing homelessness in the United States.

Last year alone, Detroit received US$40 million from the HUD program.

Those funds pay for emergency shelters, transitional housing and rapid rehousing programs – which provide temporary rental assistance and the assistance of a social worker, without preconditions – and permanent supportive housing.

Like other cities nationwide, Detroit has built its homelessness response system around HUD’s funding priorities.

For more than a decade, HUD has emphasized permanent housing. A strong body of evidence shows that stable housing leads to better long-term outcomes than temporary programs.

Color portrait of a Black man in a light blue suit and yellow tie
Current HUD Secretary Scott Turner.
Tom Williams/CQ-Roll Call Inc. via Getty Images

Prior Continuum of Care funding cycles allocated roughly 85% to 90% of funds to permanent housing, according to the National Alliance to End Homelessness.

The revised funding priorities announced in late 2025 would substantially reduce that share and redirect funding toward transitional housing and short-term interventions.

According to the Homeless Action Network of Detroit, this means that Detroit area providers could go from about $34 million per year allocated for permanent supportive housing under the current allocation to no more than about $11 million under the new priorities.

Local advocates warn that capping permanent housing at roughly 30% of Continuum of Care dollars would drastically reduce the number of supportive units available and place hundreds of households at risk of returning to homelessness.

Why permanent supportive housing matters

Permanent supportive housing is one of the most rigorously studied homelessness interventions in the United States.

It is an evidence-based intervention that provides long-term rental assistance paired with voluntary supportive services for people who have experienced chronic, or repeated, homelessness, particularly those with disabilities or chronic health conditions.

Under the current Continuum of Care framework, households typically pay no more than 30% of their income toward rent, with the subsidy covering the remainder. Assistance can continue as long as eligibility criteria are met.

Programs also offer staff to help with coordination of health care and behavioral health services and assistance identifying and applying for relevant benefits to promote long-term housing stability. Tenants hold standard leases and have the same legal protections as other renters.

Research shows that permanent supportive housing using a housing-first approach consistently reduces homelessness and improves health outcomes for people with disabilities.

Greater investment in permanent supportive housing is also linked to reductions in chronic homelessness, meaning individuals or families who have been homeless for long periods or repeatedly over time.

A long-term study published in Social Service Review in 2014 found that communities that increased permanent supportive housing capacity experienced measurable declines in chronic homelessness over time.

Local data from the Detroit Continuum of Care indicate that at least 160 new permanent supportive housing units have been made available in the past year, and another 235 units are projected for 2026. These units help people exit homelessness and maintain stable homes amid rising rents and affordability challenges.

How transitional housing compares

Transitional housing typically requires residents to participate in supportive services or programming as a condition of stay. This can include regular meetings with a social worker, employment readiness classes, substance use treatment or financial literacy workshops, for example.

The model is often used for survivors of domestic violence or young adults aging out of foster care. While transitional housing can provide short-term stability and support during these transitions, it differs from permanent supportive housing in that it is time-limited and may require program compliance as a condition of continued residency. Transitional housing placements typically last from about six months up to two years.

Exterior of building with a sign that reads: Detroit Recovery Project Inc.
Residents who live in transitional housing must comply with program requirements as a condition of their stay, which could include treatment for substance use.
Sylvia Jarrus for The Washington Post via Getty Images

However, research consistently finds that transitional housing is less likely than permanent housing to produce long-term housing stability. This is particularly the case for families and people with disabilities.

HUD’s Family Options Study in 2016 found that families offered permanent housing experienced significantly better long-term housing stability than those offered transitional housing, despite transitional housing costing more per household.

Follow-up research conducted by the Urban Institute, a nonprofit organization that studies economic policy, similarly found that many families who leave transitional housing once their time limit expires struggle to maintain stable housing. These findings are especially relevant for individuals with disabilities, chronic illnesses or mental health conditions, all groups that are typically prioritized for permanent supportive housing.

Why Detroit is especially vulnerable

Research shows that housing instability increases reliance on emergency services such as shelters, hospitals and public safety systems. This drives up taxpayer costs and additionally strains already overextended local services.

Detroit area homelessness service providers are pushing back against the potential federal changes, which they identify as “radical.”

In response, many organizations are turning to state and philanthropic partners for support while continuing to develop housing locally to help offset possible reductions in federal funding.

The Conversation

Deyanira Nevárez Martínez has received funding from the State of Michigan, the Latino Policy and Politics Institue at UCLA, the Institute for Research on Poverty at the University of Wisconsin-Madison, and the Freedom Together Foundation (formerly the JPB Foundation). She is an Assistant Professor of Urban and Regional Planning at Michigan State University and is an elected member of the Lansing City Council representing ward 2.

ref. Housing First helps people find permanent homes in Detroit − but HUD plans to divert funds to short-term solutions – https://theconversation.com/housing-first-helps-people-find-permanent-homes-in-detroit-but-hud-plans-to-divert-funds-to-short-term-solutions-274272

La maternité transforme le rapport des femmes à l’argent ainsi que la façon dont elles dépensent et épargnent

Source: The Conversation – in French – By Oriane Couchoux, Assistant Professor of Accounting, Carleton University

Les mères ne perdent pas seulement des revenus, des promotions et des possibilités d’avancement professionnel : elles dépensent aussi discrètement leur propre argent, assument davantage de dépenses quotidiennes et consentent à des sacrifices financiers qui les placent dans une situation parfois désavantageuse à long terme.


L’impact de la maternité sur le revenu des femmes est déjà bien documenté. Une étude de Statistique Canada publiée en 2015 montre que les mères gagnent 85 sous pour chaque dollar gagné par les pères. Dix ans après la naissance de leur premier enfant, les revenus des mères demeurent inférieurs d’environ 34,3 % à ce qu’ils auraient été si elles n’avaient pas eu d’enfants.




À lire aussi :
Les revenus des femmes diminuent après la naissance d’un enfant. Voici pourquoi


Au-delà de cet impact sur le revenu des mères, nos recherches révèlent que la relation des femmes avec l’argent est profondément transformée par la maternité et que le fait d’avoir des enfants modifie à la fois leurs façons de gérer leurs finances personnelles et leurs habitudes de consommation.

Les participantes à l’étude décrivent deux discours concurrents lorsqu’elles parlent de leurs finances personnelles. D’un côté, elles perçoivent la maternité comme un projet financier qu’elles doivent gérer de manière autonome, dans les limites de budgets et d’analyses coûts-bénéfices. De l’autre, elles voient la maternité comme un rôle qui exige des sacrifices financiers, où les besoins et le bien-être des enfants priment sur toute autre considération financière.

Le véritable coût de la maternité

La maternité a un coût. De nombreuses études ont montré que le fait de devenir mère a des effets négatifs sur la situation financière et la carrière des femmes.

Certaines recherches suggèrent par exemple que les compétences et l’engagement professionnel des mères peuvent être perçus de manière moins favorable par leurs collègues. Les mères font aussi face à des pressions accrues en matière de conciliation travail-famille, ce qui les conduit davantage à occuper un emploi à temps partiel. Les femmes sont en effet 19 fois plus susceptibles que les hommes de citer « la prise en charge des enfants » comme principale raison de leur travail à temps partiel.

Mais au-delà de la pénalité maternelle – le terme utilisé par les sciences sociales pour désigner ces désavantages professionnels – et de l’impact sur le revenu des mères, notre étude qualitative montre que la maternité modifie profondément la relation des femmes à l’argent.




À lire aussi :
Les femmes désirent gravir les échelons des grandes entreprises. Mais pas à n’importe quel prix


Nous avons interrogé des mères habitant au Québec afin de mieux comprendre comment elles gèrent leurs finances après l’arrivée de leurs enfants. Nos résultats montrent que la maternité transforme la façon dont les mères dépensent l’argent ainsi que la perception qu’elles ont de l’argent.

Lorsqu’on leur demande comment elles gèrent les dépenses liées à leurs enfants, les participantes à l’étude expliquent devoir composer avec des attentes sociales contradictoires qui les amènent à jongler entre deux discours : considérer l’aspect financier de la maternité comme un projet à gérer de façon responsable, mais également comme un sacrifice à consentir pour le bien-être de leurs enfants.

Devenir une stratège financière

D’un côté, les mères cherchent à être des gestionnaires financières autonomes, capables d’élaborer des stratégies et de prendre des décisions jugées économiquement responsables pour leur famille.

Comme l’explique une participante :

Tout passe dans mon compte, c’est moi qui gère. J’aime ça comme ça aussi. Je suis une personne qui est très minutieuse […] J’aime ça contrôler côté budget.

Cela conduit les mères à créer des « budgets bébé », à comparer les prix des couches dans des tableaux Excel ou à mettre en place des stratégies d’épargne pour les études futures de leurs enfants.

Cette vision d’elles-mêmes comme gestionnaires financières indépendantes, combinée à leur désir d’assumer pleinement les responsabilités financières liées aux enfants, amène parfois certaines participantes à prendre en charge seules certaines dépenses, sans nécessairement en discuter en détail avec leur coparent ou leur demander de contribuer aux dépenses quotidiennes comme l’alimentation, les vêtements ou les activités familiales.

Une autre participante décrit ce phénomène :

Je sais que j’achète plus de choses pour les enfants. Justement, je les mets sur ma carte donc je le sais que de mon côté, il y a plus des dépenses en extra. […] Mais en même temps, c’est ça que j’aime. J’aime magasiner pour eux, c’est un cadeau pour moi aussi. Mais parfois je trouve ça un peu lourd. Je me consacre vraiment beaucoup à la famille, acheter des choses pour la maison, la famille.

Le discours sociétal du sacrifice maternel

Les mères se perçoivent aussi comme les personnes ayant la charge principale des enfants, étant donc responsables de faire des sacrifices financiers pour ces derniers.

Dans ce discours, les participantes associent l’idée d’être une « bonne mère » au fait de mettre les enfants en priorité, de faire tout ce qui est possible pour assurer leur bonheur et leur bien-être, et ce sans compter le temps ni l’argent investis.

Comme l’explique une participante :

Mais c’est ça être une bonne maman […] et ça se compte pas. Tu comptes pas le temps, être présent, s’occuper d’eux, les activités, le linge, tout. Tu dépenses sans compter, c’est toi la personne vers qui ils se tournent.

Ce discours peut amener les mères, par exemple, à faire passer l’avenir de leurs enfants avant le leur en priorisant l’épargne pour les études ou en dépensant pour des biens non essentiels qui pourraient rendre leurs enfants heureux, et ce parfois au détriment de leur propre retraite.

Cette conception de la maternité qui normalise le sacrifice financier se manifeste aussi dans la réticence des mères à calculer le coût réel d’avoir des enfants et l’impact global de ces dépenses sur leur propre situation financière, comme si évaluer ces coûts était incompatible avec l’idéal maternel de dévouement.

Les répercussions financières à long terme des inégalités de genre

Ce changement dans les perspectives financières des femmes avec la maternité met en lumière certains facteurs pouvant expliquer les écarts persistants entre la situation financière des femmes et celle des hommes. Au Canada, l’écart de retraite entre les hommes et les femmes est d’environ 17 %, ce qui signifie que pour chaque dollar de revenu de retraite reçu par les hommes, les femmes reçoivent 83 sous.

La charge mentale supplémentaire assumée par les mères ne leur coûte pas seulement du temps et de l’énergie : elle pèse aussi sur leur budget.

En pratique, les responsabilités financières liées aux enfants sont parfois réparties de manière inégale au sein des couples et entre coparents, et plusieurs participantes ont expliqué qu’elles prennent en charge seules certaines responsabilités financières liées aux enfants, et ce peu importe l’impact sur leurs finances ou la contribution de l’autre parent.

À long terme, cette situation peut entraîner une diminution de l’épargne et une insécurité financière accrue à la retraite pour les mères, renforçant ainsi les inégalités d’accumulation de richesse et l’écart de retraite entre les femmes et les hommes.

Les résultats de notre étude montrent que le véritable coût de la maternité va bien au-delà de la diminution de revenus et soulignent la nécessité de mieux reconnaître le travail financier assumé par les mères dans la sphère familiale. En tant que société, nous devons mieux les soutenir.

La Conversation Canada

Oriane Couchoux a reçu du financement du Conseil de recherches en sciences humaines et du Centre for Research on Inclusion at Work (CRIW) de Carleton University.

Gabrielle Patry-Beaudoin a reçu du financement du Conseil de recherches en sciences humaines et du Centre for Research on Inclusion at Work (CRIW) de Carleton University.

ref. La maternité transforme le rapport des femmes à l’argent ainsi que la façon dont elles dépensent et épargnent – https://theconversation.com/la-maternite-transforme-le-rapport-des-femmes-a-largent-ainsi-que-la-facon-dont-elles-depensent-et-epargnent-272544

Le virage « bienveillant » du mouvement antiavortement au Québec

Source: The Conversation – in French – By Ophélie Lacroix, Étudiante au doctorat en communication et études féministes, Université du Québec à Montréal (UQAM)

Alors que l’avortement est décriminalisé au Canada depuis près de 40 ans, des oppositions à ce droit persistent et se déploient à travers des stratégies sophistiquées, parfois subtiles. Au Québec, derrière des discours soi-disant protecteurs, certaines organisations travaillent à fragiliser le libre-choix en influençant les perceptions et le débat public.


Depuis l’annonce, en novembre dernier, du projet de loi 1, visant à doter le Québec d’une Constitution provinciale, de nombreuses voix pro-choix ont exprimé leurs réserves quant à la clause visant à protéger le droit à l’avortement. Si cette prudence peut sembler contre-intuitive, elle repose sur un constat simple : la jurisprudence protège déjà efficacement l’accès à ce soin.

En février, le gouvernement a annoncé le retrait de cette disposition du projet de loi, reconnaissant que son inclusion aurait pu paradoxalement fragiliser le droit à l’avortement plutôt que de le consolider.

Cette controverse révèle une leçon plus large. Les mobilisations et discours pouvant restreindre l’accès à l’avortement ne sont pas uniquement portés par des personnes s’y opposant de manière catégorique, ostentatoire ou hostile, comme il est commun de le penser. Plus encore, des actions et discours d’apparences progressistes ou féministes peuvent tout à fait participer à restreindre le libre-choix.

C’est ainsi l’une des conclusions de notre rapport de recherche, publié en décembre dernier. Il s’appuie sur des entretiens, de l’observation participante et des collectes numériques. Il documente les espaces, stratégies et réseaux investis pour s’opposer à l’avortement au Québec. Cette recherche met en relief un continuum de positions : de l’opposition frontale aux propositions dites « intermédiaires », qui visent des restrictions partielles.

Au Québec, 59 % de la population se dit entièrement favorable au libre-choix, 5 % s’y oppose entièrement et 37 % affirme se situer « quelque part entre les deux », c’est-à-dire qu’ils adoptent une position nuancée selon le moment de la grossesse ou les circonstances, ou qu’ils ne se prononcent pas de manière définitive.




À lire aussi :
La Constitution québécoise prétend vouloir protéger les femmes. La réalité est toute autre


L’antiféminisme « bienveillant »

Les oppositions à l’état actuel du droit à l’avortement sont ainsi multiples, souvent portées par des stratégies qui relèvent de l’antiféminisme « bienveillant ». Ce discours consiste à idéaliser les femmes dans les rôles traditionnels, et à les considérer comme des êtres moralement purs, à protéger et choyer.

Sur la question de l’avortement, l’antiféminisme « hostile » blâme les femmes pour les avortements tandis que l’antiféminisme « bienveillant » les envisage comme des victimes de la culture de l’avortement. Cette logique sous-entend que les femmes doivent en être sauvées tout en niant leur capacité à prendre des décisions en matière de santé reproductive.

Les chercheurs Paul Saurette and Kelly Gordon parlent, ainsi, d’un tournant « pro-femme » chez le mouvement antiavortement au Canada anglais, phénomène que nous avons également documenté au Québec. Comme l’efficacité de l’antiféminisme « bienveillant » repose notamment sur sa difficulté à être repéré, il importe d’en révéler la présence dans les actions du mouvement antiavortement.

« Protéger » les femmes de l’avortement

Dans un premier temps, notons comment le mouvement antiavortement du Québec travaille à apparaître comme le « réel défenseur » des intérêts des femmes, en signifiant vouloir protéger ces dernières des « dangers » de l’avortement. Ainsi, nos données présentent comment plusieurs organisations de défense de droits ou d’offre de services véhiculent de la désinformation concernant les « risques » associés à l’avortement afin de décourager son recours.

Plusieurs ressources antiavortement alertent, notamment, face au « syndrome post-avortement », suggérant que ce soin causerait l’infertilité, la dépression ou encore le cancer. Or, la littérature scientifique a démenti ces affirmations à plusieurs reprises.

Cette même logique transparaît dans la sphère politique, notamment avec le projet de loi C-311 (2023), qui visait à « protéger les femmes » en alourdissant les peines pour les agressions contre les femmes enceintes, permettant, de la sorte, de reconnaître le statut juridique du fœtus.

À cette catégorie d’arguments s’ajoutent ceux visant à protéger les fœtus féminins, notamment la dénonciation de l’avortement sexo-sélectif. Cette posture « intermédiaire » invite à revoir l’état actuel du droit à l’avortement sous prétexte que les fœtus féminins feraient l’objet de discrimination. Alors qu’il n’existe aucune donnée au Canada permettant d’avancer qu’il s’agirait bel et bien d’un enjeu, cet argument apparaît dans de nombreux cas utilisés pour relancer le débat sur l’avortement.




À lire aussi :
Active Clubs : le corps comme champ de bataille de l’extrême droite


Proposer une « troisième voie »

La récupération tactique du féminisme s’exprime aussi par la promotion, au sein du mouvement antiavortement, d’une prétendue « troisième voie », présentée comme une alternative dépassant la polarisation pro‑choix et antiavortement. Les militants et organisations qui s’y associent, notamment des centres d’aide à la grossesse, affirment agir non pas contre les femmes et leurs droits, mais bien « pour » le bien-être de ces dernières et des « enfants à naître ».

En mettant de l’avant des valeurs perçues comme universelles (compassion, générosité, accompagnement) et en évitant de mobiliser des termes militants ou religieux, ces discours dépolitisent l’avortement en reformulant la question dans des termes du care. L’objectif est alors d’apparaître attractif pour un large public, tout en légitimant une position restrictive par rapport au libre-choix.


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L’exemple des centres d’aide à la grossesse

De façon encore plus concrète, notre rapport confirme la présence de 10 centres d’aide à la grossesse actifs au Québec. Ces organisations se définissent comme des lieux de soutien et d’écoute pour les femmes vivant une grossesse non planifiée, mais leur intervention s’inscrit dans une perspective d’opposition à l’avortement. L’enjeu de ce genre de ressource se situe ainsi dans le décalage entre l’image publique et l’orientation idéologique des interventions qui y ont lieu.

Parfois décriées dans l’espace médiatique, ces organisations offrent toute une gamme de services concrets (don de denrées, articles pour bébés, tests de grossesse) ainsi que de l’accompagnement humain ou spirituel, y compris des conseils (orientés) pour la prise de décision relative à la grossesse. Sous le couvert d’aider les femmes, les centres d’aide à la grossesse, qui travaillent à intégrer le maillage communautaire de différentes régions du Québec, agissent comme relais d’attitudes antiavortement et contribuent à les normaliser.

Un mouvement opportuniste et organisé

Le mouvement antiavortement du Québec se montrant diversifié, opportuniste et organisé, il est essentiel d’apprendre à reconnaître ces mobilisations plus subtiles afin de protéger convenablement le libre-choix.

C’est dans cette optique que la première recommandation de notre rapport de recherche invite à « s’abstenir d’intervenir sur le plan juridique en matière d’avortement ». Même si ces interventions peuvent sembler féministes, elles risquent en réalité de fragiliser l’accès aux soins.

La Conversation Canada

Ophélie Lacroix reçoit des financements du Conseil de recherches en sciences humaines du Canada pour sa thèse.

ref. Le virage « bienveillant » du mouvement antiavortement au Québec – https://theconversation.com/le-virage-bienveillant-du-mouvement-antiavortement-au-quebec-273858

La danse permet d’améliorer l’équilibre et de réduire le risque de chutes chez les femmes âgées

Source: The Conversation – in French – By Emma Hsiaowen Chen, PhD Candidate in Health & Exercise Science, Concordia University

*L’exercice physique permet de réduire le risque de chutes, qui constitue une cause importante de blessures chez les personnes âgées. Cependant, seules 4 % des Canadiennes de plus de 65 ans font 30 minutes d’activité physique par jour. *


Doctorante en sciences de la santé et de l’exercice à l’Université Concordia, je m’intéresse à l’élaboration de programmes d’entraînement à l’équilibre amusants et accessibles, sous forme de cours de danse offerts en ligne.

La danse peut être une façon de faire de l’exercice sans s’en rendre compte. Plusieurs études ont démontré que la danse favorise les relations sociales, a un effet positif sur l’humeur et les fonctions cognitives, tout en améliorant la mobilité, l’endurance et la marche.

C’est également un excellent moyen de travailler son équilibre, car l’apprentissage des pas de danse exige une grande précision dans les mouvements, ce qui permet de renforcer la proprioception (la perception des mouvements et de la position dans l’espace). Cela peut aider à améliorer ou à maintenir la stabilité posturale.


Cet article fait partie de notre série La Révolution grise. La Conversation vous propose d’analyser sous toutes ses facettes l’impact du vieillissement de l’imposante cohorte des boomers sur notre société, qu’ils transforment depuis leur venue au monde. Manières de se loger, de travailler, de consommer la culture, de s’alimenter, de voyager, de se soigner, de vivre… découvrez avec nous les bouleversements en cours, et à venir.


Âge et stabilité posturale

La stabilité posturale désigne la capacité à rester debout et à contrôler la position du corps dans l’espace. Elle repose sur les systèmes sensoriel et moteur. La vue permet de repérer les obstacles potentiels ou les risques de trébuchement, le système cochléo-vestibulaire de l’oreille interne contribue au sens de l’orientation et de l’ouïe, et enfin, le système somato-sensoriel, qui comprend le sens du toucher, de la douleur, de la température et de la position du corps, permet de percevoir les surfaces sous les pieds.

Une fois ces signaux sensoriels parvenus au cerveau, ils sont triés, puis la réponse motrice appropriée est sélectionnée pour être exécutée par notre système musculosquelettique.

Avec l’âge, la stabilité posturale diminue en raison des changements dans les systèmes sensoriels. Nous mesurons ce déclin chez quelqu’un en lui demandant de se tenir aussi immobile que possible, puis en observant ses mouvements et son balancement. Si une personne se balance beaucoup, on considère qu’elle a peu de stabilité et qu’elle est plus à risque de chute.

Les recherches menées sur différents cours de danse donnés en présence ont systématiquement démontré une amélioration de la stabilité posturale et une réduction du risque de chute. Toutefois, ces cours ne sont pas accessibles pour tout le monde. De nombreuses femmes âgées sont confrontées à des obstacles qui les empêchent de faire de l’exercice, comme le manque de moyen de transport, leur rôle d’aidante à domicile ou l’inaccessibilité des installations sportives. De plus, les professeurs de danse spécialisés se trouvent plutôt dans les grandes villes. Les cours de danse en virtuel peuvent réduire ces obstacles et être plus accessibles pour les personnes âgées.

Un studio de danse à la maison

Andreas Bergdahl, Mary Roberts et moi avons publié dans l’International Journal of Exercise Science les résultats de notre étude, qui démontre que les cours de danse virtuels améliorent la stabilité posturale, l’équilibre dynamique et la force des mollets chez les femmes âgées. Dans le cadre de ce projet, nous avons offert sur Zoom des cours de 75 minutes inspirés du ballet moderne, deux fois par semaine, pendant 12 semaines, à des Montréalaises de 65 ans et plus.

Chaque cours commençait par un échauffement de 15 minutes, suivi de :

  • pliés (on plie les genoux)

  • tendus (debout sur une jambe, on tend l’autre)

  • enchaînement de balancés (déplacements sur un rythme de valse)

  • enchaînement de Jose Limón/ Martha Graham (style de danse moderne qui met l’accent sur le redressement après une chute et les formes arrondies de la colonne vertébrale)

  • retour au calme avec des étirements assis

Ces exercices ont été choisis parce qu’ils mettent l’accent sur le transfert de poids, l’équilibre sur une jambe, le fait de décentrer le corps ainsi que la contraction des muscles des jambes et du tronc. Un assistant était présent sur Zoom afin d’apporter un soutien technique et de veiller à la sécurité des participantes.

Avant le premier cours, à mi-parcours et à la fin de l’étude, les participantes ont passé des évaluations en personne de la force musculaire des jambes, de l’équilibre dynamique et de la stabilité posturale.

En l’espace de six semaines, on a pu observer une réduction du balancement latéral debout (balancement médio-latéral) et une amélioration de l’équilibre dynamique. Les muscles de leurs mollets avaient également gagné en force, ce qu’on a évalué par le nombre de levers des talons effectués en 30 secondes.


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Ces améliorations peuvent se traduire par une aisance accrue dans les activités quotidiennes qui nécessitent un transfert de poids, comme la marche, la descente d’un trottoir ou même des tâches ménagères, comme passer le balai.

Bénéfices des cours en ligne

Les cours de danse en mode virtuel peuvent jouer un rôle important pour toucher les personnes qui pourraient être laissées pour compte, et ce, même après les confinements liés à la Covid-19.

Pour les personnes vivant dans des régions isolées, les aidants qui ne peuvent s’éloigner trop longtemps de leurs proches ou les personnes âgées qui ont peur de marcher dans les rues verglacées en hiver, les programmes en ligne sont accessibles et offrent de nouvelles possibilités de socialisation et d’activité physique. Ils constituent également une occasion d’exprimer sa créativité dans le confort de son foyer.

Notre recherche actuelle explore les bienfaits de différents programmes de danse offerts en ligne, associés à un entraînement avec restriction du flux sanguin, pour les personnes âgées. Cette approche offre davantage d’options adaptées aux intérêts et aux besoins des personnes en matière de mobilité. Nous nous efforçons de diffuser notre programme au sein de différentes collectivités. À ce jour, notre travail a touché des femmes âgées au Canada, au Mexique, en Colombie et en Espagne, et les a encouragées à demeurer actives et autonomes.

Même si beaucoup d’entre nous ont repris les cours en personne, n’oublions pas les avantages de l’offre en ligne. Inviter le studio de danse à la maison permet de créer des liens, de socialiser et d’améliorer son équilibre.

La Conversation Canada

Emma Hsiaowen Chen bénéficie d’un financement du Fonds de recherche du Québec – Santé – Formation de doctorat 2024-2025. Son travail de maîtrise présenté ici a été financé par les Bourses d’études supérieures du Canada – Programme de maîtrise 2022 et le Fonds de recherche du Québec – Santé – Formation de maîtrise 2022-2023. Elle travaille comme professeure de danse indépendante spécialisée dans l’enseignement aux personnes âgées.

ref. La danse permet d’améliorer l’équilibre et de réduire le risque de chutes chez les femmes âgées – https://theconversation.com/la-danse-permet-dameliorer-lequilibre-et-de-reduire-le-risque-de-chutes-chez-les-femmes-agees-271161