Clashing visions of Mexicos GMO corn ban cloud impact – Reuters

A farmer holds different types of corn cobs in Otzolotepec, on the outskirts of Mexico City, February 7, 2017. REUTERS/Carlos Jasso/File Photo

MEXICO CITY, July 8 (Reuters) – A clash at the top of Mexico’s agriculture ministry over the scope of President Andres Manuel Lopez Obrador’s push to prohibit genetically-modified corn has cast uncertainty over the farm and food industries in the country that first developed the grain.

If liberally interpreted and successfully implemented, the new rules could ban imports of GMO corn by 2024, ending a dependence that last year stood at some 16 million tonnes of imported yellow corn, almost all of it from American farmers and used to feed Mexico’s massive livestock sector.

A more restrictive interpretation of the planned ban could allow GMO corn for animal feed – and save the U.S. exports.

Agriculture Minister Victor Villalobos believes animal feed will not ultimately be covered by the ban, according to an official with knowledge of the minister’s thinking. Earlier this year Villalobos assured U.S. agriculture chief Tom Vilsack that imported GMO corn for animal feed will be exempted. read more

However, there are signs that Villalobos and his moderate allies have not yet won that battle and may be losing.

The planned restrictions were outlined on Dec. 31 in a presidential decree. It was ambiguously worded – the result of behind-scenes wrangling between factions in the agriculture ministry, one headed by the minister and the other by his deputy, according to three sources with knowledge of the matter.

Six months later, amid contradictory comments by the opposing factions, Lopez Obrador has not committed one way of the other, and farmers and food processors remain on tenterhooks.

In the anti-GMO corner, Villalobos’ deputy, leftist former congressman Victor Suarez pitches “agroecological” farming and routinely rails against big agribusiness. His faction’s influence led to the decree, which shocked industry by ruling GMO corn could not be used “in the diet of Mexicans” after 2024.

Suarez has said animal feed, and therefore large GMO imports, will be prohibited. read more

In another sign of the influence of his vein of thinking in the administration, sources close to health regulator COFEPRIS said its leadership is aligned with Suarez. The agency has since late 2018 halted all approvals for new GMO corn varieties sought by top seed companies like Germany’s Bayer (BAYGn.DE) and U.S.-based Corteva (CTVA.N).

And Villalobos, a market-friendly scientist who has long championed biotech crops, made an unsuccessful attempt to soften the decree before it was published, another senior ministry official said.

The agriculture ministry declined multiple requests to make Villalobos available for an interview. Suarez declined to discuss any differences with Villalobos.

Over a dozen Mexican farm industry leaders consulted by Reuters said they were increasingly concerned that the GMO ban would apply to animal feed despite Villalobos’ assurances.

The text of the decree specifies that the agriculture, environment and health ministries as well as a science council Conacyt will interpret it, and officials in charge of the latter three are all believed by several industry leaders to be sympathetic to Suarez’s views.

None of the agencies involved responded to requests for comment.

Juan Cortina, president of the National Farm Council (CNA)lobby, said there is no clarity on what they will decide. It is “totally wrong” to assume corn imports for livestock will be exempted, he said.

“The most sensitive aspect of this is whether or not it will apply to animal feed,” he added.


Lopez Obrador said this month he may seek out additional corn imports to keep a lid on creeping prices for corn tortillas, the country’s main staple, underscoring an overarching sensitivity for the leftist leader.

But the industry is right to be worried: Lopez Obrador has a track record of confounding critics and taking drastic steps in line with his nationalist, big business-skeptic views.

Despite assurances to industry from moderates in his cabinet, he scrapped a $13 billion partially-built airport project and has moved to increase state control of the energy sector.

“The agriculture minister just doesn’t agree with the president’s instructions,” according to the second senior official, who spoke on condition of anonymity to freely discuss the internal discord.

The ministry declined to comment about the clashes.

An official close to Villalobos said such policy differences were a normal part of government.

The U.S. Department of Agriculture in a January report took note of Mexican health regulator COFEPRIS’ failure to approve new GMO permits – for corn or any other crops – since Lopez Obrador took office nearly three years ago.

Mexico’s top farm lobby CNA has pointed to at least eight newly-developed varieties of GMO corn sought by companies that are pending.

Industry sources say big grain buyers in Mexico such as global commodities giant Cargill (CARG.UL) could be forced as soon as next year to find new U.S. suppliers as existing ones begin to plant and harvest the newer corn varieties.

Corn imports will not affected this year by the regulatory freeze on new seed approvals, according to an executive with a top grains trader in Mexico, but he said it remains unclear how the flow could be impacted in subsequent years depending on how officials address what he described as “ambiguities” in the decree’s text.

GMO bans have vocal support from activists in Mexico, the birthplace of modern corn. The activists have for years blasted already-detected GMO contamination in fields planted with native strains of the grain.

The possibility of a broad GMO ban, twinned with a more fully-formed policy to prohibit the widely-used weed killer glyphosate, has been lauded by environmental groups such as Greenpeace.

Under Lopez Obrador, more decision making goes through the president, and regulators under his control have broad authority to limit imports.

There is no deadline for Lopez Obrador to take a decision beyond the 2024 end-date for the ban specified in the decree and it is not clear when he will do so.

Until he decides, the future will remain unclear for Mexico’s $12 billion livestock sector, which has over years preferred imported U.S. yellow corn due to significant logistical and cost advantages.

Two years ago, Senator Jesusa Rodriguez, a Suarez ally from Lopez Obrador’s MORENA party, proposed a ban on non-native corn varieties.

Lopez Obrador ultimately opposed the idea on fears it would cause corn prices to soar, according to a source who attended a pivotal meeting with the president.

Industry hopes the same argument will ultimately prevail even as backers like Rodriguez continue to push for bold action to turn the page on agrochemicals and gene-spliced crops in order to embrace a more sustainable farming future.

“There shouldn’t be anything that stops it,” she said of the decree.

Reporting by David Alire Garcia; Additional reporting by Adriana Barrera; Editing by Alistair Bell

Our Standards: The Thomson Reuters Trust Principles.

Venezuela resorts to upgraded oil, blends for feeding refineries -document, sources – Reuters

  • Zuata Sweet, Hamaca 22 crudes going to Amuay refinery
  • Crude processing at PDVSA’s refineries fell in June
  • Changes are expected to free light oil for diluting

CARACAS, July 8 (Reuters) – Venezuela’s state-run oil company PDVSA has started producing two upgraded crude grades for domestic refining, aiming at reanimating the country’s much-needed output of motor fuels, according to a company document and sources close the decision.

Years of under-investment in PDVSA’s 1.3 million-barrel-per-day capacity refining network and U.S. sanctions since 2019 have led to intermittent scarcity of cooking gas, gasoline and diesel, making the nation more dependent on imports and forcing Venezuelans to line up for hours and even days to get fuel.

As Venezuela’s refineries were originally built to process medium to light crudes, PDVSA’s increasingly heavy oil output no longer meets the facilities’ diet, forcing the company to decide every month whether to refine its limited stocks of light oil or use it as diluent for its flagship exportable grade Merey.

Following the restart of a key upgrader in June, operated by the Petrocedeno joint venture, PDVSA has scheduled the first cargo of light Zuata Sweet synthetic crude to be sent this month to its largest refinery, the 645,000-bpd Amuay, which remained mostly shut in June, according to the document and one of the sources.

PDVSA had stopped producing Zuata Sweet and other upgraded crudes in 2019 shortly after U.S. sanctions deprived the firm and its private partners from the largest market for those grades, the U.S. Gulf.

The state company last month also began production of a new upgraded crude grade, Hamaca 22, at neighboring project Petropiar, with the first 500,000-barrel cargo loading this week at the Jose port bound for Amuay, the document showed.

“We do not have enough crude for refining. We are now trying to feed several refineries with these new crudes,” said a company source, who asked to remain anonymous as they were not authorized to speak publicly.

The company’s fuel production has fallen since May after slightly rising in the first four months of the year. Venezuela also imported diesel to ease the lack of motor fuels. read more

Amuay’s three-week paralysis, the continued outage of the El Palito refinery and low output at the Puerto La Cruz refinery contributed to the decline, for a total average of 193,000 barrels per day (bpd) of crude processed last month, 15% of the nation’s installed capacity, the source said.

The 310,000-bpd Cardon has been the only refinery with stable output around 120,000 bpd this year, two sources added.

PDVSA earlier this year began formulating a crude blend similar to its medium Leona by mixing grades from the Orinoco belt with diluents. That crude has since fed Amuay and Cardon, according to internal company documents.

The move to use blends and upgraded crudes for domestic refining is not only expected to allow more motor fuel output, but it would also free Mesa 30 crude to be used in production of exportable Merey, likely solving bottlenecks that in recent months have caused delays for loading cargoes bound for Asia. read more

Reporting by Marianna Parraga in Mexico City and Deisy Buitrago in Caracas; Editing by Daniel Wallis

Our Standards: The Thomson Reuters Trust Principles.

Giant pandas no longer endangered but still vulnerable, says China

The latest classification upgrade “reflects their improved living conditions and China’s efforts in keeping their habitats integrated”, said Cui Shuhong, head of the Ministry of Ecology and Environment’s Department of Nature and Ecology Conservation at a news conference.

Eric Adams, Once a Political Outsider, Conquers the Inside Game

A review of his fund-raising practices by The New York Times earlier this year showed that he has pushed the boundaries of campaign-finance and ethics laws, though he has not been formally accused of wrongdoing. And the last month of the campaign saw controversies over transparency issues play out concerning his tax and real estate disclosures and even questions of residency, culminating in an extraordinary moment in which Mr. Adams offered journalists a tour of the apartment where he said he lived.

Mr. Adams’s formative years in the public eye were spent in the Police Department, where he helped found an organization called 100 Blacks in Law Enforcement Who Care. His efforts inspired some and rankled other colleagues on the force who describe a career trajectory that was more complex than Mr. Adams sometimes suggests.

But to this day, some voters remember Mr. Adams from those efforts, which helped him dispatch arguments from opponents that he was overly inclined to embrace policing as an answer to the city’s challenges.

“My admiration for him really started when he was a policeman talking about police brutality, and a captain talking about police officers not fulfilling their oath,” said Charles B. Rangel, the former New York congressman, who endorsed Mr. Adams.

As an outspoken police officer, Mr. Adams had his share of controversies, too, aligning himself at various times with Louis Farrakhan, the Nation of Islam leader who has repeatedly promoted anti-Semitism, and the ex-boxer Mike Tyson after his 1992 rape conviction. Mr. Adams lost a 1994 congressional run, and he was also a registered Republican for a period of time in the 1990s.

In 2006, he was elected to the State Senate as a Democrat, part of a wave of Central Brooklyn politicians who came up from outside the party, and in 2013, won an election to be Brooklyn borough president.

Mr. Adams, who became an evangelist for veganism after he says he reversed his diabetes by reforming his diet and exercise routines, became known for preparing vegan meals at Borough Hall, and he developed a reputation as a splashy New York character prone to making unexpected remarks and appearances. There was the gruesome rat-related news conference, for instance, or Mr. Adams’s announcement that he, as a former law enforcement officer, would begin bringing a gun to houses of worship after a massacre in a Pittsburgh synagogue.

Euros 2020: What all of us can learn from Gareth Southgate

Members (all unpaid volunteers) include Sir Dave Brailsford, a cycling coach, Colonel Lucy Giles, commander of the Sandhurst Military Academy, the Olympic rower Kath Grainger, Manoj Badale, a tech entrepreneur, the rugby coach Stuart Lancaster and David Sheepshanks, mastermind behind the St George’s Park national football centre.

Explainer: Why did Pope Francis need surgery? – Reuters

Pope Francis walks after the weekly general audience at the San Damaso courtyard, at the Vatican, June 30, 2021. REUTERS/Guglielmo Mangiapane/File Photo

ZURICH, July 6 (Reuters) – Pope Francis will be in hospital for at least the rest of this week, recovering after a planned surgery to remove one side of his intestine for a medical condition known as symptomatic diverticular stenosis of the colon. read more

Many people as they age suffer from so-called diverticula, or small, bulging sacs that form on the lining of the small or large intestine, but the pope was among those for whom the problem demanded an operation.

In his case, the Vatican said he suffered from “symptomatic diverticular stenosis”, in which sac-like pouches that protruded from the muscular layer of his colon caused it to narrow. Diverticular disease can cause pain, inflammation and trouble passing stools.


The pope is 84 years old, and age may be a factor since 50% of people over 60 years may develop bulges in the colon, though often without symptoms, according to the U.S. Cleveland Clinic. Still, many develop so-called diverticulitis, whose symptoms include pain, nausea and fever that accompanies inflammation of these bulging sacs.

Some develop stenosis, or narrowing of the colon, that for the pope required surgical intervention.


It’s not completely clear, but age, diet and lifestyle, and genetics likely play a role, according to Britain’s National Health Service.

As people age, their large intestines’ walls grow weaker, and the pressure of passing hard stools may cause sacs, or diverticula, to form. For some people, smoking, obesity and long-term use of painkillers like ibuprofen or aspirin may contribute to risks, doctors said.


Some people may require antibiotics to resolve an acute case of diverticulitis, and doctors may recommend a high-fibre diet, according to the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.

In cases like the stenosis suffered by the pope, doctors may decide to remove the unhealthy section of the colon, then reconnect the healthy sections.


Typically, the bowel stops working for a few days following surgery. In some cases, doctors can’t rejoin the ends of the colon immediately, so a surgeon does a temporary colostomy before later rejoining the colon’s healthy tissue during a second surgery, the U.S. National Institutes of Health said.

In its statements, the Vatican has not mentioned a colostomy.

People typically go home within 10 days – the pope plans to stay in Rome’s Gemelli hospital for seven, barring complications, a spokesperson said – but it may take three months to recover fully, according to guidance from the Australian government’s health agency. The pope always suspends most public activities in July, giving him a month of near-total rest time, and August is also very slow at the Vatican.

Two days after surgery, his spokesman said routine tests were good and that the pope had eaten breakfast and read several newspapers.


The Mayo Clinic advises that a low-fibre diet for years may put people at risk of developing diverticulitis. Lack of exercise may also be a risk factor, though even people who are physically active may develop symptoms.

Eating foods rich in fibre, plus drinking adequate fluids, can be helpful in keeping such conditions from returning, though as many as 60-70% of people who experienced one bout of diverticulitis may see it come back.

Reporting by John Miller;
Editing by Josephine Mason, Alexandra Hudson

Our Standards: The Thomson Reuters Trust Principles.

Tell us: what’s your best gluten-free recipe?

A significant number of people now avoid eating foods which contain gluten – but that needn’t mean compromising on taste. With this in mind, we want to hear your favourite gluten-free recipes.

Perhaps you know the secret to the perfect gluten-free loaf, or how to bake a delicious gluten-free cake? Or maybe you know a pasta alternative that’s always a hit – whether you’re following a gluten-free diet or not? Whatever your gluten-free top tip may be, tell us about it below.

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Evolution of the dad

The "bearded hipster dad," as documented by Getty Images, is a particularly unique creature in the larger animal kingdom. (Well, technically, all human dads are.)
Enlarge / The “bearded hipster dad,” as documented by Getty Images, is a particularly unique creature in the larger animal kingdom. (Well, technically, all human dads are.)

Jessie Casson / Getty Images

Lee Gettler is hard to get on the phone, for the very ordinary reason that he’s busy caring for his two young children. Among mammals, though, that makes him extraordinary.

“Human fathers engage in really costly forms of care,” says Gettler, an anthropologist at the University of Notre Dame. In that way, humans stand out from almost all other mammals. Fathers, and parents in general, are Gettler’s field of study. He and others have found that the role of dads varies widely between cultures—and that some other animal dads may give helpful glimpses of our evolutionary past.

Many mysteries remain, though, about how human fathers evolved their peculiar, highly invested role, including the hormonal changes that accompany fatherhood (see sidebar below). A deeper understanding of where dads came from, and why fatherhood matters for both fathers and children, could benefit families of all kinds.

“If you look at other mammalian species, fathers tend to do nothing but provide sperm,” says Rebecca Sear, an evolutionary demographer and anthropologist at the London School of Hygiene and Tropical Medicine. Moms carry the burden in most other animals that care for their kids, too. (Fish are an exception—most don’t tend their young at all, but the caring parents are usually dads. And bird couples are famous for co-parenting.)

Even among the other apes, our closest relatives, most dads don’t do much. That means moms are stuck with all the work and need to space out their babies to make sure they can care for them. Wild chimps give birth every four to six years, for example; orangutans wait as long as six to eight years between young.

The ancestors of humans, though, committed to a different strategy. Mothers got help from their community and their kin, including fathers. This freed them up enough to have more babies, closer together—about every three years, on average, in today’s nonindustrial societies. That strategy “is part of the evolutionary success story of humans,” Gettler says.

Don't let this male gorillas scowl fool you—he likely lets kids hang around.
Enlarge / Don’t let this male gorillas scowl fool you—he likely lets kids hang around.

Paul Zinken/picture alliance via Getty Images

Doting gorilla dads

Some clues about the origin of doting fatherhood come from our close primate relatives. Stacy Rosenbaum, a biological anthropologist at the University of Michigan, studies wild mountain gorillas in Rwanda. These gorillas provide intriguing hints about the origins of ape dads, as Gettler and coauthors Rosenbaum and Adam Boyette argue in the 2020 Annual Review of Anthropology.

Mountain gorillas are a type of eastern gorilla. They differ from western gorillas—a separate species, more often seen in zoos—in their habitat and diet. Rosenbaum is more interested in another thing that sets mountain gorillas apart: “Kids spend a ton of time around males,” she says.

Those males may or may not be their dads. Male mountain gorillas don’t seem to know or care which young are theirs. But nearly all males tolerate the company of kids. Unlike any other great ape that’s been studied in the wild, these males—bruisers twice the size of females, with huge muscles and teeth—are essentially babysitters. Some pick up the kids, play with them and even sleep cuddled together.

This male company can protect very young gorillas against predators, and it keeps the young from being killed by intruding males. Another important benefit might be social, Rosenbaum speculates. The young gorillas mingling around an adult male might pick up social skills like human toddlers do from their peers at daycare. Additionally, research has shown that the relationships between young gorillas and adult males persist as those kids grow up.

Another tantalizing hint about how male gorillas benefit the young in their group comes from a recent paper on young mountain gorillas whose mothers died. Losing their mothers didn’t make these orphans more likely to die themselves, the researchers found. Nor did they experience other costs, such as a longer wait before having their own young. The orphans’ relationships with others in their group, especially dominant males, seemed to protect them from ill effects.

Mountain gorilla males aren’t the only primates to ally with kids. Adult male macaques also spend time with young. And baboon males form “friendships” with females and their young, which are often (but not always) their own offspring. These behaviors cost the male primates almost nothing. So while the males may give their own kids a survival boost, it’s not a big deal if they spend time with some unrelated kids too.

Are dads sexy?

But babysitting may benefit male gorillas in another way, too: by making them more attractive. “One of our speculations is that females actually prefer mating with males who do a lot of interacting with kids,” Rosenbaum says. She’s found that male gorillas who do more babysitting earlier in life go on to father many more children when they’re older. Macaques, too, seem to be more attractive to females if they’ve spent more time hanging out with kids.

Anthropologists used to assume that fatherly behavior could evolve only in monogamous animals, Rosenbaum says. Species like the mountain gorillas undermine that assumption. They also show that, despite what scientists have long thought, male animals don’t have to choose between spending their energy on mating or parenting. It seems taking care of kids can be a way of getting mates.

Studies of human dads and stepdads have hinted at the same idea. “A lot of guys will willingly enter into relationships with kids they know aren’t theirs,” says Kermyt Anderson, a biological anthropologist at the University of Oklahoma. That investment might seem paradoxical from an evolutionary perspective. But Anderson’s research suggests that men invest in stepkids and even biological kids partly as an investment in their relationship with the mother. When that relationship ends, fathers tend to become less involved.

A human dad who cares for his children or stepchildren is different, of course, from an ape or monkey who just lets kids hang around. But Gettler and Rosenbaum wonder whether our own ancestors had similar habits to a mountain gorilla or macaque. Under the evolutionary pressures they faced, these friendly tendencies toward kids could have ratcheted up into devoted fatherhood.

Many kinds of fatherhood

It’s clear human fathers are unusual in their attention to their children. “However, it’s also clear that fatherhood in humans is quite variable,” Sear says. Not all dads are doting, or even present.

But that doesn’t necessarily affect basic survival. In a 2008 paper, Sear and coauthor Ruth Mace asked whether children with absent fathers are likelier to die. They reviewed data on child survival from 43 studies of populations around the world, mostly those without access to modern medical care. They found that in a third of the studies looking at fathers, kids were more likely to survive childhood when their dad was around. But in the other two-thirds, fatherless kids did just as well. (By contrast, every study of children without mothers found they were less likely to survive.)

“That is not what you would expect to see if fathers are really vital for children to thrive,” Sear says. Rather, she suspects that what’s vital are the jobs fathers perform. When a father is missing, others in the family or community can fill in. “It may be that the fathering role is important, but it’s substitutable by other social group members,” she says.

What is that role? Historically, Gettler says, anthropologists have viewed fatherhood as all about “provisioning”—bringing home the bacon, literally. In some foraging communities, more successful hunters also father more kids. But Gettler hopes to help expand the definition of a dad. Research has shown that fathers can have important roles in directly caring for their children, for example, and teaching children language and social skills. Fathers may also help their children by cultivating relationships in their communities, Gettler says. When it comes to survival, “Networking can be everything.”

A dad’s job also varies culturally. For example, in the Republic of the Congo, Gettler works with two neighboring communities. The Bondongo are fishers and farmers; they value fathers who take risks to gain food for their own families. Their neighbors, the BaYaka, are foragers who value fathers who share their resources outside their families.

“In the West we have this idealization of the nuclear family,” says Sear: a self-reliant, heterosexual couple in which Dad does all the provisioning and Mom all the childcare. But worldwide, she says, families like this are very rare. A child’s biological parents may not live together exclusively, for life or at all, Sear writes in a recent paper. Childcare and food can come from either parent—or neither. Among the Himba of Namibia, for instance, children are often fostered by extended family.

“Possibly the key defining feature of our species is our behavioral flexibility,” Sear says. Assuming that certain roles are “natural” for fathers or mothers can make parents feel isolated and stressed, Sear writes. She hopes research can broaden our understanding of what fathers are for, and what a human family is. That might help societies to better support families of all kinds—whether they have dads like Gettler who are busy chasing the children around, or dads who are away fishing, or no dads at all.

“I think we need to take a much more nonjudgmental view of the human family, and the kinds of family structures in which children can thrive,” Sear says, “to improve the health of mothers, fathers and children.”

Editor’s note: This story was updated on June 16, 2021, to correct the name of the country where the Bondongo and BaYaka live. It is the Republic of the Congo, not the Democratic Republic of the Congo, as was originally stated.

Elizabeth Preston is a freelance science journalist who lives in the Boston area with her husband and two small, highly dependent primates.

This article originally appeared in Knowable Magazine, an independent journalistic endeavor from Annual Reviews. Sign up for the newsletter.

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Just don’t do it: 10 exercise myths

Yesterday at an outdoor coffee shop, I met my old friend James in person for the first time since the pandemic began. Over the past year on Zoom, he looked just fine, but in 3D there was no hiding how much weight he’d gained. As we sat down with our cappuccinos, I didn’t say a thing, but the first words out of his mouth were: “Yes, yes, I’m now 20lb too heavy and in pathetic shape. I need to diet and exercise, but I don’t want to talk about it!”

If you feel like James, you are in good company. With the end of the Covid-19 pandemic now plausibly in sight, 70% of Britons say they hope to eat a healthier diet, lose weight and exercise more. But how? Every year, millions of people vow to be more physically active, but the vast majority of these resolutions fail. We all know what happens. After a week or two of sticking to a new exercise regime we gradually slip back into old habits and then feel bad about ourselves.

Clearly, we need a new approach because the most common ways we promote exercise – medicalising and commercialising it – aren’t widely effective. The proof is in the pudding: most adults in high-income countries, such as the UK and US, don’t get the minimum of 150 minutes per week of physical activity recommended by most health professionals. Everyone knows exercise is healthy, but prescribing and selling it rarely works.

I think we can do better by looking beyond the weird world in which we live to consider how our ancestors as well as people in other cultures manage to be physically active. This kind of evolutionary anthropological perspective reveals 10 unhelpful myths about exercise. Rejecting them won’t transform you suddenly into an Olympic athlete, but they might help you turn over a new leaf without feeling bad about yourself.

Myth 1: It’s normal to exercise

Whenever you move to do anything, you’re engaging in physical activity. In contrast, exercise is voluntary physical activity undertaken for the sake of fitness. You may think exercise is normal, but it’s a very modern behaviour. Instead, for millions of years, humans were physically active for only two reasons: when it was necessary or rewarding. Necessary physical activities included getting food and doing other things to survive. Rewarding activities included playing, dancing or training to have fun or to develop skills. But no one in the stone age ever went for a five-mile jog to stave off decrepitude, or lifted weights whose sole purpose was to be lifted.

Myth 2: Avoiding exertion means you are lazy

Whenever I see an escalator next to a stairway, a little voice in my brain says, “Take the escalator.” Am I lazy? Although escalators didn’t exist in bygone days, that instinct is totally normal because physical activity costs calories that until recently were always in short supply (and still are for many people). When food is limited, every calorie spent on physical activity is a calorie not spent on other critical functions, such as maintaining our bodies, storing energy and reproducing. Because natural selection ultimately cares only about how many offspring we have, our hunter-gatherer ancestors evolved to avoid needless exertion – exercise – unless it was rewarding. So don’t feel bad about the natural instincts that are still with us. Instead, accept that they are normal and hard to overcome.

Fed-up woman holding a lot of exercise equipment

‘For most of us, telling us to “Just do it” doesn’t work’: exercise needs to feel rewarding as well as necessary. Photograph: Dan Saelinger/

Myth 3: Sitting is the new smoking

You’ve probably heard scary statistics that we sit too much and it’s killing us. Yes, too much physical inactivity is unhealthy, but let’s not demonise a behaviour as normal as sitting. People in every culture sit a lot. Even hunter-gatherers who lack furniture sit about 10 hours a day, as much as most westerners. But there are more and less healthy ways to sit. Studies show that people who sit actively by getting up every 10 or 15 minutes wake up their metabolisms and enjoy better long-term health than those who sit inertly for hours on end. In addition, leisure-time sitting is more strongly associated with negative health outcomes than work-time sitting. So if you work all day in a chair, get up regularly, fidget and try not to spend the rest of the day in a chair, too.

Myth 4: Our ancestors were hard-working, strong and fast

A common myth is that people uncontaminated by civilisation are incredible natural-born athletes who are super-strong, super-fast and able to run marathons easily. Not true. Most hunter-gatherers are reasonably fit, but they are only moderately strong and not especially fast. Their lives aren’t easy, but on average they spend only about two to three hours a day doing moderate-to-vigorous physical activity. It is neither normal nor necessary to be ultra-fit and ultra-strong.

Myth 5: You can’t lose weight walking

Until recently just about every weight-loss programme involved exercise. Recently, however, we keep hearing that we can’t lose weight from exercise because most workouts don’t burn that many calories and just make us hungry so we eat more. The truth is that you can lose more weight much faster through diet rather than exercise, especially moderate exercise such as 150 minutes a week of brisk walking. However, longer durations and higher intensities of exercise have been shown to promote gradual weight loss. Regular exercise also helps prevent weight gain or regain after diet. Every diet benefits from including exercise.

Myth 6: Running will wear out your knees

Many people are scared of running because they’re afraid it will ruin their knees. These worries aren’t totally unfounded since knees are indeed the most common location of runners’ injuries. But knees and other joints aren’t like a car’s shock absorbers that wear out with overuse. Instead, running, walking and other activities have been shown to keep knees healthy, and numerous high-quality studies show that runners are, if anything, less likely to develop knee osteoarthritis. The strategy to avoiding knee pain is to learn to run properly and train sensibly (which means not increasing your mileage by too much too quickly).

Myth 7: It’s normal to be less active as we age

After many decades of hard work, don’t you deserve to kick up your heels and take it easy in your golden years? Not so. Despite rumours that our ancestors’ life was nasty, brutish and short, hunter-gatherers who survive childhood typically live about seven decades, and they continue to work moderately as they age. The truth is we evolved to be grandparents in order to be active in order to provide food for our children and grandchildren. In turn, staying physically active as we age stimulates myriad repair and maintenance processes that keep our bodies humming. Numerous studies find that exercise is healthier the older we get.

Myth 8: There is an optimal dose/type of exercise

One consequence of medicalising exercise is that we prescribe it. But how much and what type? Many medical professionals follow the World Health Organisation’s recommendation of at least 150 minutes a week of moderate or 75 minutes a week of vigorous exercise for adults. In truth, this is an arbitrary prescription because how much to exercise depends on dozens of factors, such as your fitness, age, injury history and health concerns. Remember this: no matter how unfit you are, even a little exercise is better than none. Just an hour a week (eight minutes a day) can yield substantial dividends. If you can do more, that’s great, but very high doses yield no additional benefits. It’s also healthy to vary the kinds of exercise you do, and do regular strength training as you age.

Myth 9: ‘Just do it’ works

Let’s face it, most people don’t like exercise and have to overcome natural tendencies to avoid it. For most of us, telling us to “just do it” doesn’t work any better than telling a smoker or a substance abuser to “just say no!” To promote exercise, we typically prescribe it and sell it, but let’s remember that we evolved to be physically active for only two reasons: it was necessary or rewarding. So let’s find ways to do both: make it necessary and rewarding. Of the many ways to accomplish this, I think the best is to make exercise social. If you agree to meet friends to exercise regularly you’ll be obliged to show up, you’ll have fun and you’ll keep each other going.

Myth 10: Exercise is a magic bullet

Finally, let’s not oversell exercise as medicine. Although we never evolved to exercise, we did evolve to be physically active just as we evolved to drink water, breathe air and have friends. Thus, it’s the absence of physical activity that makes us more vulnerable to many illnesses, both physical and mental. In the modern, western world we no longer have to be physically active, so we invented exercise, but it is not a magic bullet that guarantees good health. Fortunately, just a little exercise can slow the rate at which you age and substantially reduce your chances of getting a wide range of diseases, especially as you age. It can also be fun – something we’ve all been missing during this dreadful pandemic.

Daniel E Lieberman is professor of Human Evolutionary Biology at Harvard and author of Exercised: The Science of Physical Activity, Rest and the Pursuit of Health (Penguin, £9.99). Buy a copy for £9.29 at

We won’t fix the obesity epidemic by locking people’s jaws shut | Arwa Mahdawi


This is an economic issue, and a ‘torture device’ that stops you opening your mouth properly isn’t the solution

Tue 29 Jun 2021 11.04 EDT

Want to hear a weight-loss idea so ingenious it’s guaranteed to make your jaw drop by exactly 2mm? Introducing the DentalSlim Diet Control: a terrifying contraption that uses magnets cemented to your teeth to stop you opening your mouth by more than a couple of millimetres. That makes eating pretty difficult, causing you to shed weight along with your dignity. The device was developed by a team of researchers from the UK and New Zealand to “to help fight the global obesity epidemic” and is designed to be fitted by dentists. Which reaffirms all my worst suspicions about dentists.

It will not surprise you to hear that news of the oral chastity belt did not go down well with the angry hordes on Twitter: there was an immediate backlash, with people online comparing it to a “medieval torture device”. Perhaps more importantly, however, the device doesn’t seem to have thrilled the few people who have actually used it. For reasons that are not immediately clear, the device was trialled exclusively on women. Only six participants completed the study and while they lost weight and reported feeling embarrassed by their mouth-magnets only “occasionally”, they noted that “life in general was less satisfying”. The participants were all armed with an emergency tool they could use to unlock their mouths should the need arise. No one reported using it, but one person did admit to cheating the system by chugging melted chocolate.

The DentalSlim Diet Control (a mouthful of a name) has been touted as a “world first” by its inventors. But there is nothing new about jaw-wiring: as the researchers themselves note, it was popular in the 1980s. Nor is there anything new about people treating the obesity epidemic as if it is a simple matter of individual willpower rather than complex systemic change. In the rich world, obesity is an economic issue: the less money you have, the less access to healthy food you often have. And that’s not a problem you can solve by locking people’s jaws shut.

Arwa Mahdawi is a Guardian columnist.












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