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Atlantic sturgeon were fished almost to extinction − ancient DNA reveals how Chesapeake Bay population changed over centuries

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theconversation.com – Natalia Przelomska, Research Associate in Archaeogenomics, National Museum of Natural History, Smithsonian Institution – 2025-03-20 07:47:00

Sturgeon can be several hundred pounds each.
cezars/E+ via Getty Images

Natalia Przelomska, Smithsonian Institution and Logan Kistler, Smithsonian Institution

Sturgeons are one of the oldest groups of fishes. Sporting an armor of five rows of bony, modified scales called dermal scutes and a sharklike tail fin, this group of several-hundred-pound beasts has survived for approximately 160 million years. Because their physical appearance has changed very little over time, supported by a slow rate of evolution, sturgeon have been called living fossils.

Despite their survival through several geological time periods, many present-day sturgeon species are at threat of extinction, with 17 of 27 species listed as “critically endangered.”

Conservation practitioners such as the Virginia Commonwealth University monitoring team are working hard to support recovery of Atlantic sturgeon in the Chesapeake Bay area. But it’s not clear what baseline population level people should strive toward restoring. How do today’s sturgeon populations compare with those of the past?

Three people carefully lower a large fish over the side of a boat toward the water
VCU monitoring team releases an adult Atlantic sturgeon back into the estuary.
Matt Balazik

We are a molecular anthropologist and a biodiversity scientist who focus on species that people rely on for subsistence. We study the evolution, population health and resilience of these species over time to better understand humans’ interaction with their environments and the sustainability of food systems.

For our recent sturgeon project, we joined forces with fisheries conservation biologist Matt Balazik, who conducts on-the-ground monitoring of Atlantic sturgeon, and Torben Rick, a specialist in North American coastal zooarchaeology. Together, we wanted to look into the past and see how much sturgeon populations have changed, focusing on the James River in Virginia. A more nuanced understanding of the past could help conservationists better plan for the future.

Sturgeon loomed large for millennia

In North America, sturgeon have played important subsistence and cultural roles in Native communities, which marked the seasons by the fishes’ behavioral patterns. Large summertime aggregations of lake sturgeon (Acipenser fulvescens) in the Great Lakes area inspired one folk name for the August full moon – the sturgeon moon. Woodland Era pottery remnants at archaeological sites from as long as 2,000 years ago show that the fall and springtime runs of Atlantic sturgeon (Acipenser oxyrinchus) upstream were celebrated with feasting.

triangular-shaped bone with round cavities
Archaeologists uncover bony scutes – modified scales that resemble armor for the living fish – in places where people relied on sturgeon for subsistence.
Logan Kistler and Natalia Przelomska

Archaeological finds of sturgeon remains support that early colonial settlers in North America, notably those who established Jamestown in the Chesapeake Bay area in 1607, also prized these fish. When Captain John Smith was leading Jamestown, he wrote “there was more sturgeon here than could be devoured by dog or man.” The fish may have helped the survival of this fortress-colony that was both stricken with drought and fostering turbulent relationships with the Native inhabitants.

This abundance is in stark contrast to today, when sightings of migrating fish are sparse. Exploitation during the past 300 years was the key driver of Atlantic sturgeon decline. Demand for caviar drove the relentless fishing pressure throughout the 19th century. The Chesapeake was the second-most exploited sturgeon fishery on the Eastern Seaboard up until the early 20th century, when the fish became scarce.

Man pulls large fish over side of boat
Conservation biologists capture the massive fish for monitoring purposes, which includes clipping a tiny part of the fin for DNA analysis.
Matt Balazik

At that point, local protection regulations were established, but only in 1998 was a moratorium on harvesting these fish declared. Meanwhile, abundance of Atlantic sturgeon remained very low, which can be explained in part by their lifespan. Short-lived fish such as herring and shad can recover population numbers much faster than Atlantic sturgeon, which live for up to 60 years and take a long time to reach reproductive age – up to around 12 years for males and as many as 28 years for females.

To help manage and restore an endangered species, conservation biologists tend to split the population into groups based on ranges. The Chesapeake Bay is one of five “distinct population segments” the U.S. Endangered Species Act listing in 2012 created for Atlantic sturgeon.

Since then, conservationists have pioneered genetic studies on Atlantic sturgeon, demonstrating through the power of DNA that natal river – where an individual fish is born – and season of spawning are both important for distinguishing subpopulations within each regional group. Scientists have also described genetic diversity in Atlantic sturgeon; more genetic variety suggests they have more capacity to adapt when facing new, potentially challenging conditions.

map highlighting Maycock's Point, Hatch Site, Jamestown and Williamsburg on the James River
The study focused on Atlantic sturgeon from the Chesapeake Bay region, past and present. The four archaeological sites included are highlighted.
Przelomska NAS et al., Proc. R. Soc. B 291: 20241145, CC BY

Sturgeon DNA, then and now

Archaeological remains are a direct source of data on genetic diversity in the past. We can analyze the genetic makeup of sturgeons that lived hundreds of years ago, before intense overfishing depleted their numbers. Then we can compare that baseline with today’s genetic diversity.

The James River was a great case study for testing out this approach, which we call an archaeogenomics time series. Having obtained information on the archaeology of the Chesapeake region from our collaborator Leslie Reeder-Myers, we sampled remains of sturgeon – their scutes and spines – at a precolonial-era site where people lived from about 200 C.E. to about 900 C.E. We also sampled from important colonial sites Jamestown (1607-1610) and Williamsburg (1720-1775). And we complemented that data from the past with tiny clips from the fins of present-day, live fish that Balazik and his team sampled during monitoring surveys.

scattering of small bone shards spilling out of ziplock bag, with a purple-gloved hand
Scientists separate Atlantic sturgeon scute fragments from larger collections of zooarchaeological remains, to then work on the scutes in a lab dedicated to studying ancient DNA.
Torben Rick and Natalia Przelomska

DNA tends to get physically broken up and biochemically damaged with age. So we relied on special protocols in a lab dedicated to studying ancient DNA to minimize the risk of contamination and enhance our chances of successfully collecting genetic material from these sturgeon.

Atlantic sturgeon have 122 chromosomes of nuclear DNA – over five times as many as people do. We focused on a few genetic regions, just enough to get an idea of the James River population groupings and how genetically distinct they are from one another.

We were not surprised to see that fall-spawning and spring-spawning groups were genetically distinct. What stood out, though, was how starkly different they were, which is something that can happen when a population’s numbers drop to near-extinction levels.

We also looked at the fishes’ mitochondrial DNA, a compact molecule that is easier to obtain ancient DNA from compared with the nuclear chromosomes. With our collaborator Audrey Lin, we used the mitochondrial DNA to confirm our hypothesis that the fish from archaeological sites were more genetically diverse than present-day Atlantic sturgeon.

Strikingly, we discovered that mitochondrial DNA did not always group the fish by season or even by their natal river. This was unexpected, because Atlantic sturgeon tend to return to their natal rivers for breeding. Our interpretation of this genetic finding is that over very long timescales – many thousands of years – changes in the global climate and in local ecosystems would have driven a given sturgeon population to migrate into a new river system, and possibly at a later stage back to its original one. This notion is supported by other recent documentation of fish occasionally migrating over long distances and mixing with new groups.

Our study used archaeology, history and ecology together to describe the decline of Atlantic sturgeon. Based on the diminished genetic diversity we measured, we estimate that the Atlantic sturgeon populations we studied are about a fifth of what they were before colonial settlement. Less genetic variability means these smaller populations have less potential to adapt to changing conditions. Our findings will help conservationists plan into the future for the continued recovery of these living fossils.The Conversation

Natalia Przelomska, Research Associate in Archaeogenomics, National Museum of Natural History, Smithsonian Institution and Logan Kistler, Curator of Archaeobotany and Archaeogenomics, National Museum of Natural History, Smithsonian Institution

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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When you lose your health insurance, you may also lose your primary doctor – and that hurts your health

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theconversation.com – Jane Tavares, Senior Research Fellow and Lecturer of Gerontology, UMass Boston – 2025-06-17 07:36:00


Losing health insurance or switching to plans with limited preventive care disrupts the critical bond with primary care providers, leading to missed checkups, late diagnoses, worsening health, and higher medical expenses. Research shows that consistent care improves health, lowers costs, and ensures timely preventive services. Millions risk losing Medicaid coverage amid congressional budget debates, threatening these vital connections for low-income and disabled Americans. Uninsured individuals postpone care, leading to emergencies that raise costs across the health system. Medicaid acts as a health lifeline, enabling ongoing care and preventing crisis-driven treatment. Cutting funding could fracture care relationships, harming health outcomes and increasing system-wide costs.

Seeing the same doctor on a regular basis is good for your health.
Morsa Images/DigitalVision via Getty Images

Jane Tavares, UMass Boston and Marc Cohen, UMass Boston

When you lose your health insurance or switch to a plan that skimps on preventive care, something critical breaks.

The connection to your primary care provider, usually a doctor, gets severed. You stop getting routine checkups. Warning signs get missed. Medical problems that could have been caught early become emergencies. And because emergencies are both dangerous and expensive, your health gets worse while your medical bills climb.

As gerontology researchers who study health and financial well-being in later life, we’ve analyzed how someone’s ties to the health care system strengthen or unravel depending on whether they have insurance coverage. What we’ve found is simple: Staying connected to a trusted doctor keeps you healthier and saves the system money. Breaking that link does just the opposite.

And that’s exactly what has us worried right now. Members of Congress are debating whether to make major cuts to Medicaid and other social safety net programs. If the Senate passes its own version of the tax-and-spending package that the House approved in May 2025, millions of Americans will soon face exactly this kind of disruption – with big consequences for their health and well-being.

How people end up uninsured

Someone can lose their health insurance for a number of reasons. For many Americans, coverage is tied to employment. Being fired, retiring before you turn 65 and become eligible to enroll in the Medicare program, or even getting a new job can mean losing insurance. Others wind up uninsured due to a different array of changes: moving to a different state, getting divorced or aging out of a parent’s plan after their 26th birthday.

And those who buy their own coverage may find that they can no longer afford the premiums. In 2024, average premiums on the individual market exceeded more than US$600 per month for many adults, even with subsidies.

Government-sponsored insurance programs can also leave you vulnerable to this predicament. The Senate is currently considering its own version of a tax-and-spending bill the House of Representatives passed in May that would make cuts and changes to Medicaid. If the provisions in the House bill are enacted, millions of Americans who get health insurance through Medicaid – a health insurance program jointly run by the federal government and the states that is mainly for people who have low incomes or disabilities – would lose their coverage, according to the nonpartisan Congressional Budget Office.

Medicaid was established in the 1960s, explains a scholar of the program’s history.

Consequences of becoming uninsured

Health insurance is more than a way to pay medical bills; it’s a doorway into the health care system itself. It connects people to health care providers who come to know their medical history, their medications and their personal circumstances.

When that door closes, the effects are immediate. Uninsured people are much less likely to have a usual source of care – typically a doctor or another primary care provider or clinic you know and trust. That relationship acts as a foundation for managing chronic conditions, staying current with preventive screenings and getting guidance when new symptoms arise.

Researchers have found that adults who go uninsured for even six months become significantly more likely to postpone care or forgo it altogether to save money. In practical terms, this means they’re less likely to be examined by someone who knows their medical history and can spot red flags early.

The Affordable Care Act, the landmark health care law enacted during the Obama administration, made the number of Americans without insurance plummet. The share of people without insurance fell from 16% in 2010 to 7.7% in 2023.

The people who got insurance coverage, particularly those who were middle age, saw big improvements in their health.

Researching the results

In research that looked at data collected from 2014 to 2020, we followed what happened to 12,000 adults who were 50 or older and lived across the nation.

Our research team analyzed how their experiences changed when they lost, and sometimes later regained, a regular source of care during those six years.

Many of the participants in this study had multiple chronic conditions like diabetes, hypertension and heart disease.

The results were striking.

Those who didn’t see the same provider on a regular basis were far less likely to feel heard or respected by health care professionals. They had fewer medical appointments, filled fewer prescriptions and were less likely to follow through with recommended treatments.

Their health also deteriorated considerably over the six years. Their blood pressure and blood sugar levels rose, and they had more elevated indicators of kidney impairment compared with their counterparts who had regular care providers.

The longer they went without consistent health care, the worse these clinical markers became.

Warning signs

Preventive care is one of the best tools that both patients and their health care providers have to head off major health problems. This care includes screenings like cholesterol and blood pressure checks, mammograms, PAP smears and prostate exams, as well as routine vaccinations. But most people only get preventive care when they stay engaged with the health care system.

And that’s far more likely when you have stable and comprehensive health insurance coverage.

Our research team also examined what happened to preventive care based on whether the participants had a regular doctor. We found that those who kept seeing the same providers were almost three times more likely to get basic preventive services than those who did not.

Over time, these missed preventive care opportunities can add up to a big problem. They can turn what could have been a manageable issue into an emergency room visit or a long, expensive hospital stay.

For example, imagine a man in his 50s who no longer gets cholesterol screenings after losing insurance coverage. Over several years, his undiagnosed high cholesterol leads to a heart attack that could have been prevented with early medication. Or a woman who skips mammograms because of out-of-pocket costs, only to face a late-stage cancer diagnosis that might have been caught years earlier.

People in scrubs work and mill about in a hospital emergency room.
Waiting too long to deal with a health condition can mean you make a trip to the emergency room, increasing the cost of care for you and others.
FS Productions/Tetra images via Getty Images

Shifting the costs

Patients whose conditions take too long to be diagnosed aren’t the only ones who pay the price.

We also studied how stable care relationships affect health care spending. To do this, we linked Medicare claims cost data to our original study and tracked the medical costs of the same adults age 50 and older from 2014 to 2020. One of our key findings is that people with regular care providers were 38% less likely to incur above-average health care costs.

These savings aren’t just for patients – they ripple through the entire health care system. Primary care stability lowers costs for both public and private health insurers and, ultimately, for taxpayers.

But when people lose their health care coverage, those savings disappear.

Emergency rooms see more uninsured patients seeking care that could have been handled earlier and more cheaply in a clinic or doctor’s office. While hospitals are legally required to provide emergency care regardless of a patient’s ability to pay, much of the resulting cost goes unreimbursed.

Hospitals foot the bill for about two-thirds of those losses. They pass the other third along to private insurance companies through higher hospital fees. Those insurers, in turn, raise their customers’ premiums. Larger taxpayer subsidies can then be required to keep hospitals open.

Seeing Medicaid as a lifeline

For the nearly 80 million Americans enrolled in Medicaid, the program provides more than coverage.

It contributes to the health care stability our research shows is critical for good health. Medicaid makes it possible for many Americans with serious medical conditions to have a regular doctor, get routine preventive services and have someone to turn to when symptoms arise – even when they have low incomes. It helps prevent health care from becoming purely crisis-driven.

As Congress considers cutting Medicaid funding by hundreds of billions of dollars, we believe that lawmakers should realize that scaling back coverage would break the fragile links between millions of patients and the providers who know them best.The Conversation

Jane Tavares, Senior Research Fellow and Lecturer of Gerontology, UMass Boston and Marc Cohen, Professor of Gerontology, UMass Boston

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Note: The following A.I. based commentary is not part of the original article, reproduced above, but is offered in the hopes that it will promote greater media literacy and critical thinking, by making any potential bias more visible to the reader –Staff Editor.

Political Bias Rating: Left-Leaning

This article presents a strong case in favor of maintaining or expanding government-funded health insurance programs like Medicaid, using empirical research to emphasize the benefits of continuous coverage and the harms of potential cuts. While it relies on data and expert opinion, the framing consistently warns against proposed Republican-led cuts to Medicaid, characterizing them as harmful and disruptive. The language portrays these policy shifts in a negative light, without presenting counterarguments or alternative fiscal perspectives, which contributes to a left-leaning tone in support of social safety nets and expansive health care coverage.

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Making facsimiles of the dead raises ethical quandaries

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theconversation.com – Nir Eisikovits, Professor of Philosophy and Director, Applied Ethics Center, UMass Boston – 2025-06-17 07:36:00


AI reanimations of the dead—used in courtrooms, concerts, and classrooms—are raising serious ethical concerns. These deepfakes may lack the consent of the deceased and risk distorting their legacy. While some argue they can educate or inspire, critics say such re-creations manipulate emotions and potentially exploit the dead for political, legal, or commercial gain. Unlike griefbots, which help loved ones cope, reanimations present a curated illusion that may conflict with the person’s real beliefs. By making the dead “speak” again, we risk cheapening their memory and overlooking our own ability to reflect, imagine, and interpret their lives with integrity.

This screenshot of an AI-generated video depicts Christopher Pelkey, who was killed in 2021.
Screenshot: Stacey Wales/YouTube

Nir Eisikovits, UMass Boston and Daniel J. Feldman, UMass Boston

Christopher Pelkey was shot and killed in a road range incident in 2021. On May 8, 2025, at the sentencing hearing for his killer, an AI video reconstruction of Pelkey delivered a victim impact statement. The trial judge reported being deeply moved by this performance and issued the maximum sentence for manslaughter.

As part of the ceremonies to mark Israel’s 77th year of independence on April 30, 2025, officials had planned to host a concert featuring four iconic Israeli singers. All four had died years earlier. The plan was to conjure them using AI-generated sound and video. The dead performers were supposed to sing alongside Yardena Arazi, a famous and still very much alive artist. In the end Arazi pulled out, citing the political atmosphere, and the event didn’t happen.

In April, the BBC created a deep-fake version of the famous mystery writer Agatha Christie to teach a “maestro course on writing.” Fake Agatha would instruct aspiring murder mystery authors and “inspire” their “writing journey.”

The use of artificial intelligence to “reanimate” the dead for a variety of purposes is quickly gaining traction. Over the past few years, we’ve been studying the moral implications of AI at the Center for Applied Ethics at the University of Massachusetts, Boston, and we find these AI reanimations to be morally problematic.

Before we address the moral challenges the technology raises, it’s important to distinguish AI reanimations, or deepfakes, from so-called griefbots. Griefbots are chatbots trained on large swaths of data the dead leave behind – social media posts, texts, emails, videos. These chatbots mimic how the departed used to communicate and are meant to make life easier for surviving relations. The deepfakes we are discussing here have other aims; they are meant to promote legal, political and educational causes.

Chris Pelkey was shot and killed in 2021. This AI ‘reanimation’ of him was presented in court as a victim impact statement.

Moral quandaries

The first moral quandary the technology raises has to do with consent: Would the deceased have agreed to do what their likeness is doing? Would the dead Israeli singers have wanted to sing at an Independence ceremony organized by the nation’s current government? Would Pelkey, the road-rage victim, be comfortable with the script his family wrote for his avatar to recite? What would Christie think about her AI double teaching that class?

The answers to these questions can only be deduced circumstantially – from examining the kinds of things the dead did and the views they expressed when alive. And one could ask if the answers even matter. If those in charge of the estates agree to the reanimations, isn’t the question settled? After all, such trustees are the legal representatives of the departed.

But putting aside the question of consent, a more fundamental question remains.

What do these reanimations do to the legacy and reputation of the dead? Doesn’t their reputation depend, to some extent, on the scarcity of appearance, on the fact that the dead can’t show up anymore? Dying can have a salutary effect on the reputation of prominent people; it was good for John F. Kennedy, and it was good for Israeli Prime Minister Yitzhak Rabin.

The fifth-century B.C. Athenian leader Pericles understood this well. In his famous Funeral Oration, delivered at the end of the first year of the Peloponnesian War, he asserts that a noble death can elevate one’s reputation and wash away their petty misdeeds. That is because the dead are beyond reach and their mystique grows postmortem. “Even extreme virtue will scarcely win you a reputation equal to” that of the dead, he insists.

Do AI reanimations devalue the currency of the dead by forcing them to keep popping up? Do they cheapen and destabilize their reputation by having them comment on events that happened long after their demise?

In addition, these AI representations can be a powerful tool to influence audiences for political or legal purposes. Bringing back a popular dead singer to legitimize a political event and reanimating a dead victim to offer testimony are acts intended to sway an audience’s judgment.

It’s one thing to channel a Churchill or a Roosevelt during a political speech by quoting them or even trying to sound like them. It’s another thing to have “them” speak alongside you. The potential of harnessing nostalgia is supercharged by this technology. Imagine, for example, what the Soviets, who literally worshipped Lenin’s dead body, would have done with a deep fake of their old icon.

Good intentions

You could argue that because these reanimations are uniquely engaging, they can be used for virtuous purposes. Consider a reanimated Martin Luther King Jr., speaking to our currently polarized and divided nation, urging moderation and unity. Wouldn’t that be grand? Or what about a reanimated Mordechai Anielewicz, the commander of the Warsaw Ghetto uprising, speaking at the trial of a Holocaust denier like David Irving?

But do we know what MLK would have thought about our current political divisions? Do we know what Anielewicz would have thought about restrictions on pernicious speech? Does bravely campaigning for civil rights mean we should call upon the digital ghost of King to comment on the impact of populism? Does fearlessly fighting the Nazis mean we should dredge up the AI shadow of an old hero to comment on free speech in the digital age?

a man in a suit and tie stands in front of a microphone
No one can know with certainty what Martin Luther King Jr. would say about today’s society.
AP Photo/Chick Harrity

Even if the political projects these AI avatars served were consistent with the deceased’s views, the problem of manipulation – of using the psychological power of deepfakes to appeal to emotions – remains.

But what about enlisting AI Agatha Christie to teach a writing class? Deep fakes may indeed have salutary uses in educational settings. The likeness of Christie could make students more enthusiastic about writing. Fake Aristotle could improve the chances that students engage with his austere Nicomachean Ethics. AI Einstein could help those who want to study physics get their heads around general relativity.

But producing these fakes comes with a great deal of responsibility. After all, given how engaging they can be, it’s possible that the interactions with these representations will be all that students pay attention to, rather than serving as a gateway to exploring the subject further.

Living on in the living

In a poem written in memory of W.B. Yeats, W.H. Auden tells us that, after the poet’s death, Yeats “became his admirers.” His memory was now “scattered among a hundred cities,” and his work subject to endless interpretation: “the words of a dead man are modified in the guts of the living.”

The dead live on in the many ways we reinterpret their words and works. Auden did that to Yeats, and we’re doing it to Auden right here. That’s how people stay in touch with those who are gone. In the end, we believe that using technological prowess to concretely bring them back disrespects them and, perhaps more importantly, is an act of disrespect to ourselves – to our capacity to abstract, think and imagine.The Conversation

Nir Eisikovits, Professor of Philosophy and Director, Applied Ethics Center, UMass Boston and Daniel J. Feldman, Senior Research Fellow, Applied Ethics Center, UMass Boston

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Note: The following A.I. based commentary is not part of the original article, reproduced above, but is offered in the hopes that it will promote greater media literacy and critical thinking, by making any potential bias more visible to the reader –Staff Editor.

Political Bias Rating: Centrist

This content presents a balanced and thoughtful discussion on the ethical implications of using AI to “reanimate” deceased individuals’ likenesses. It raises concerns about consent, legacy, manipulation, and the moral responsibilities involved, without advocating strongly for or against a particular political ideology. The examples and references span different contexts and perspectives, from legal and political uses to educational applications, addressing both potential risks and benefits. The tone is analytical, focused on ethical considerations rather than partisan viewpoints, aligning it with a centrist approach to the topic.

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Robots run out of energy long before they run out of work to do − feeding them could change that

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theconversation.com – James Pikul, Associate Professor of Mechanical Engineering, University of Wisconsin-Madison – 2025-06-02 07:45:00


Earlier this year, a robot completed a half-marathon in just under 2 hours 40 minutes, showcasing impressive agility but limited endurance. Unlike animals that store energy in dense fat, robots rely on lithium-ion batteries, which offer far less energy density and require frequent recharging, limiting operational time. Current robots like Boston Dynamics’ Spot function for around 90 minutes per charge, far less than biological endurance. New battery chemistries and fast-charging technologies may help, but challenges remain. Researchers are exploring bioinspired “robotic metabolism” systems, where robots “digest” fuels and circulate energy like blood, promising enhanced endurance, adaptability, and resilience beyond current limitations.

Robots can run, but they can’t go the distance.
AP Photo/Ng Han Guan

James Pikul, University of Wisconsin-Madison

Earlier this year, a robot completed a half-marathon in Beijing in just under 2 hours and 40 minutes. That’s slower than the human winner, who clocked in at just over an hour – but it’s still a remarkable feat. Many recreational runners would be proud of that time. The robot kept its pace for more than 13 miles (21 kilometers).

But it didn’t do so on a single charge. Along the way, the robot had to stop and have its batteries swapped three times. That detail, while easy to overlook, speaks volumes about a deeper challenge in robotics: energy.

Modern robots can move with incredible agility, mimicking animal locomotion and executing complex tasks with mechanical precision. In many ways, they rival biology in coordination and efficiency. But when it comes to endurance, robots still fall short. They don’t tire from exertion – they simply run out of power.

As a robotics researcher focused on energy systems, I study this challenge closely. How can researchers give robots the staying power of living creatures – and why are we still so far from that goal? Though most robotics research into the energy problem has focused on better batteries, there is another possibility: Build robots that eat.

Robots move well but run out of steam

Modern robots are remarkably good at moving. Thanks to decades of research in biomechanics, motor control and actuation, machines such as Boston Dynamics’ Spot and Atlas can walk, run and climb with an agility that once seemed out of reach. In some cases, their motors are even more efficient than animal muscles.

But endurance is another matter. Spot, for example, can operate for just 90 minutes on a full charge. After that, it needs nearly an hour to recharge. These runtimes are a far cry from the eight- to 12-hour shifts expected of human workers – or the multiday endurance of sled dogs.

The issue isn’t how robots move – it’s how they store energy. Most mobile robots today use lithium-ion batteries, the same type found in smartphones and electric cars. These batteries are reliable and widely available, but their performance improves at a slow pace: Each year new lithium-ion batteries are about 7% better than the previous generation. At that rate, it would take a full decade to merely double a robot’s runtime.

Robots such as Boston Dynamic’s Atlas are remarkably capable – for relatively short amounts of time.

Animals store energy in fat, which is extraordinarily energy dense: nearly 9 kilowatt-hours per kilogram. That’s about 68 kWh total in a sled dog, similar to the energy in a fully charged Tesla Model 3. Lithium-ion batteries, by contrast, store just a fraction of that, about 0.25 kilowatt-hours per kilogram. Even with highly efficient motors, a robot like Spot would need a battery dozens of times more powerful than today’s to match the endurance of a sled dog.

And recharging isn’t always an option. In disaster zones, remote fields or on long-duration missions, a wall outlet or a spare battery might be nowhere in sight.

In some cases, robot designers can add more batteries. But more batteries mean more weight, which increases the energy required to move. In highly mobile robots, there’s a careful balance between payload, performance and endurance. For Spot, for example, the battery already makes up 16% of its weight.

Some robots have used solar panels, and in theory these could extend runtime, especially for low-power tasks or in bright, sunny environments. But in practice, solar power delivers very little power relative to what mobile robots need to walk, run or fly at practical speeds. That’s why energy harvesting like solar panels remains a niche solution today, better suited for stationary or ultra-low-power robots.

Why it matters

These aren’t just technical limitations. They define what robots can do.

A rescue robot with a 45-minute battery might not last long enough to complete a search. A farm robot that pauses to recharge every hour can’t harvest crops in time. Even in warehouses or hospitals, short runtimes add complexity and cost.

If robots are to play meaningful roles in society assisting the elderly, exploring hazardous environments and working alongside humans, they need the endurance to stay active for hours, not minutes.

New battery chemistries such as lithium-sulfur and metal-air offer a more promising path forward. These systems have much higher theoretical energy densities than today’s lithium-ion cells. Some approach levels seen in animal fat. When paired with actuators that efficiently convert electrical energy from the battery to mechanical work, they could enable robots to match or even exceed the endurance of animals with low body fat. But even these next-generation batteries have limitations. Many are difficult to recharge, degrade over time or face engineering hurdles in real-world systems.

Fast charging can help reduce downtime. Some emerging batteries can recharge in minutes rather than hours. But there are trade-offs. Fast charging strains battery life, increases heat and often requires heavy, high-power charging infrastructure. Even with improvements, a fast-charging robot still needs to stop frequently. In environments without access to grid power, this doesn’t solve the core problem of limited onboard energy. That’s why researchers are exploring alternatives such as “refueling” robots with metal or chemical fuels – much like animals eat – to bypass the limits of electrical charging altogether.

illustration off a humanoid robot putting a metal nut into its mouth
Robots could one day harvest energy from high-energy-density materials such as aluminum through synthetic digestive and vascular systems.
Yichao Shi and James Pikul

An alternative: Robotic metabolism

In nature, animals don’t recharge, they eat. Food is converted into energy through digestion, circulation and respiration. Fat stores that energy, blood moves it and muscles use it. Future robots could follow a similar blueprint with synthetic metabolisms.

Some researchers are building systems that let robots “digest” metal or chemical fuels and breathe oxygen. For example, synthetic, stomachlike chemical reactors could convert high-energy materials such as aluminum into electricity.

This builds on the many advances in robot autonomy, where robots can sense objects in a room and navigate to pick them up, but here they would be picking up energy sources.

Other researchers are developing fluid-based energy systems that circulate like blood. One early example, a robotic fish, tripled its energy density by using a multifunctional fluid instead of a standard lithium-ion battery. That single design shift delivered the equivalent of 16 years of battery improvements, not through new chemistry but through a more bioinspired approach. These systems could allow robots to operate for much longer stretches of time, drawing energy from materials that store far more energy than today’s batteries.

In animals, the energy system does more than just provide energy. Blood helps regulate temperature, deliver hormones, fight infections and repair wounds. Synthetic metabolisms could do the same. Future robots might manage heat using circulating fluids or heal themselves using stored or digested materials. Instead of a central battery pack, energy could be stored throughout the body in limbs, joints and soft, tissuelike components.

This approach could lead to machines that aren’t just longer-lasting but more adaptable, resilient and lifelike.

The bottom line

Today’s robots can leap and sprint like animals, but they can’t go the distance.

Their bodies are fast, their minds are improving, but their energy systems haven’t caught up. If robots are going to work alongside humans in meaningful ways, we’ll need to give them more than intelligence and agility. We’ll need to give them endurance.The Conversation

James Pikul, Associate Professor of Mechanical Engineering, University of Wisconsin-Madison

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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The post Robots run out of energy long before they run out of work to do − feeding them could change that appeared first on theconversation.com



Note: The following A.I. based commentary is not part of the original article, reproduced above, but is offered in the hopes that it will promote greater media literacy and critical thinking, by making any potential bias more visible to the reader –Staff Editor.

Political Bias Rating: Centrist

This article presents a factual, science- and technology-focused discussion about the challenges of energy storage in robotics. It reports on current limitations and future research directions without advocating any political ideology or policy stance. The tone is neutral and informative, emphasizing technical innovation and potential benefits without framing the topic in a partisan context. There is no language or framing that suggests a left- or right-leaning bias; instead, it adheres to objective reporting of scientific progress and challenges.

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