We know that a host of creatures ‪—​​ from whales, to snakes, to sloths ‪— pass gas. But do we know which animal is the top tooter? Experts told Live Science the answer is blowing in the wind.

"Getting quantitative measurements for farts per animal is pretty difficult," Nick Caruso, a data scientist and co-author of '"Does It Fart?: The Definitive Field Guide to Animal Flatulence'' (Quercus Publishing, 2017), told Live Science in an email.

What we can do is hypothesize using the data we do have. Expelled gas is made partially of methane, so comparing methane emissions produced by different species may provide a clue. However, this method does have limitations, experts pointed out.

Fart league

Researchers measure the methane animals produce by placing them inside respiration chambers, then inserting a capsule into the stomach that releases a tracer gas while strapping them with a harness that samples their breath. Alternatively, they capture their breath at stations where they feed or are milked.

Research points to livestock, especially cows, as major methane emitters. A recent report puts their total methane emissions at 117 teragrams per year. (One teragram is equal to 1 billion kilograms, or 2.2 billion pounds.) A buildup of cow-generated methane gas even caused a dairy shed in Germany to explode. However, contrary to what many people believe, the "overwhelming majority" of methane emissions from livestock is released through burping, not flatulence, Ermias Kebreab, a professor of animal science at the University of California, Davis, told Live Science in an email.

The reason comes down to where in the gut the gas is made. Herbivores can't break down plant material on their own; they rely on microbes in their guts to ferment it, and that fermentation releases gases such as methane and carbon dioxide, Dr. Marcus Clauss, head of research and co-director of the Clinic for Zoo Animals, Exotic Pets and Wildlife at the University of Zurich, told Live Science in an email. Some of this gas is absorbed into the bloodstream and exhaled. The rest tends to leave by the nearest exit ‪—‬ animals that ferment their food toward the front of the digestive tract mostly burp it out, while those that ferment it toward the back mostly pass it as wind, Clauss explained.

Cows and other ruminants ‪(such as buffalo, sheep, goats and camels)‬ ferment their food in a chamber called the rumen, located near the front of the digestive system, so most of the methane they produce is through belching, Matthew Hayek, an associate professor of environmental studies at New York University, told Live Science in an email.

So if it's not cows, which animal is the top farter based on their methane emissions? The best candidates are hindgut fermenters ‪—‬ herbivores that digest plant matter in the large intestine (the hindgut). Meat eaters, by contrast, typically produce far less methane than herbivores do, Clauss said.

One possible contender are termites, which break down wood and grass in their hindguts. Their global population is estimated to be around 27 quadrillion (that's 15 zeros) individuals, and they collectively emit 10 teragrams of methane per year.

But, per individual, the title might go to horses. According to a 2019 report from the Intergovernmental Panel on Climate Change, horses have the highest methane emissions among hindgut fermenters — around 40 pounds (18 kg) of methane per horse each year.

However, Clauss is skeptical. "The ranking of horse as highest is only because it has been measured," he told Live Science in an email. "But there are so many hindgut fermenters not measured, like rhino ... Who knows?"

If we consider methane emissions per unit of bodyweight, the nutria (Myocastor coypus) ‪—‬ an herbivorous, semiaquatic rodent ‪—‬ would have higher methane emissions than the horse, Clauss said.

Clauss also questioned the accuracy of using methane emissions data as an indicator of flatulence. "There is some methane in flatulence, but most likely the majority of methane produced by an animal is exhaled, i.e. it goes via blood to the lungs," he said.

So until scientists figure out how to measure animal farts, any ranking remains speculative. For now, scientists have developed ways to track intestinal gas in people, including swallowable electronic capsules that measure gases inside the gut and clip-on underwear sensors that detect hydrogen in farts.

Does animal flatulence contribute to climate change?

Methane is a particularly potent greenhouse gas when released into the atmosphere, and the quantities that large herds of cows and other ruminants emit through burping are enough to contribute to climate change. Indeed, scientists are experimenting with ways to reduce methane emissions from cattle — for example, by adding seaweed to their diet.

But animal flatulence is not a major contributor to global methane increases, Hayek said.

Even methane emissions from termite flatulence, while large, do not have an impact, Stefan Arndt, a professor of physiological and ecosystem ecology at the University of Melbourne in Australia, told Live Science in an email. "A large proportion of that methane is then consumed by methanotrophic bacteria in the soil," he said. These bacteria use methane as an energy source, thereby reducing the net methane emissions from termites substantially.

"Their emissions are part of the natural cycle of methane that has always been there for millennia," Arndt added. "The increasing methane concentrations in the atmosphere that are leading to climate change are caused by humans."

'> Which animal farts the most?

After the Russian Provisional Government was overthrown by the more extreme Bolsheviks in October 1917, Nicholas, his wife, their children and several members of the family's staff were moved to Ipatiev House in Yekaterinburg, where, in July 1918, they were executed. Their bodies were hidden and remained lost to time ‪for nearly a century —‬ until modern technology, with some help from the British royal family, unraveled the fascinating story of their disappearance.

In this excerpt from "The Secrets of Our DNA: How Genetics Has Changed the World" (Pegasus Books, 2026), author Turi King, director of the Center for Evolution at the University of Bath, looks back at the incredible story of how DNA was used to solve a major mystery of modern history: What happened to the last members of the House of Romanov?

I was sitting in a lecture theatre at Cambridge University in 1994 when one of my lecturers, Erika Hagelberg, spoke about a new study she had just been involved in. It was the first major case to combine both mitochondrial DNA and DNA fingerprinting to identify human remains: those of the Russian imperial family.

But first I need to take you back to Russia in 1917 and the abdication of the tsar following the Russian Revolution.

The Russian royal family, the Romanovs, had been the reigning imperial dynasty since 1617, and three centuries later, Tsar Nicholas II was on the throne. Nicholas was the cousin of George V, king of the United Kingdom, their mothers being sisters, and had married George's cousin Princess Alix (Alexandra) of Hesse, who was apparently Queen Victoria's favourite grandchild. Nicholas and Alix had five children, four daughters (Olga, Tatiana, Maria and Anastasia) and a son, Alexei.

The tsar and his wife were not well liked by the Russian population and political unrest culminated in the revolution of 1917, when Nicholas was forced to abdicate. The family were kept under house arrest and in 1918 they were moved to Ipatiev House in Yekaterinburg with the royal physician, Dr Botkin, and three of their staff. On the night of 16 July, the family, their doctor and staff were herded into the cellar together and executed. Their bodies were then taken to a secret location and placed in a hastily dug communal grave, doused in sulphuric acid in an attempt to disfigure them and hinder identification, and then covered over, the location of the grave being lost for more than 70 years.

Ironically, the new Russian government had wanted to get the Romanovs out of Russia due to the risk of their becoming a rallying point, but a plan to grant asylum to the Romanovs in the U.K. because of their links with the British royal family fell through, owing to a reluctance on the part of George V to grant it. Yet those links with the British royal family would eventually prove crucial in their identification.

Fast-forward to 1991, when several skeletons were found in a shallow grave some 20 miles from Yekaterinburg. Many of the bones were badly damaged but it was possible to determine, based on examination of the skeletal remains, that there were nine individuals — two short of the 11 killed that night. The faces of the skulls were badly damaged in all of the skeletons, all of them showing evidence of violence either in the form of bullet holes or bayonet wounds or both. Before the genetic study, Russian forensic scientists had used numerous techniques alongside historical data to tentatively identify the remains as some of the members of the Russian royal family, their doctor and servants.

These included examining the bones, to determine approximate age and sex, and some of the teeth, the expensive dental work, incorporating gold, platinum and porcelain, indicating that certain remains must belong to members of an aristocratic family. The team worked out that the two missing individuals would have been two of the children, one of the daughters (while it was hard to determine which one it would be, given how close in age they were, it was thought that it was either Maria or Anastasia) and the son, Prince Alexei.

The Russian chief forensic medical examiner then contacted a team in the U.K., which included Erika, to see if genetic evidence could be used to confirm the identification. The U.K. team used the amelogenin genetic sex test, now part of standard forensic DNA testing, which confirmed the sex of the skeletons (four male and five female bodies), while an early form of DNA profiling showed that there was a family group here — two parents and three children — and four unrelated individuals. So far, so good.

Next, they needed to prove that this was the Russian royal family, and they did this using mitochondrial DNA analysis. As you'll remember, mitochondrial DNA is passed down by a mother to all her children, male and female, but only daughters can pass it on — so if female-line family members of Tsar Nicholas and Tsarina Alexandra could be found and would agree to give a DNA test, their mitochondrial DNA should match that of their royal ancestors. It just so happened that the late Prince Philip, husband of the late Queen Elizabeth, was related to the tsarina through the female line: she was his great-aunt, his maternal grandmother being the sister of the tsarina. He kindly gave a DNA sample.

The testing that they did was standard for the time in that they looked at two regions known as hypervariable regions 1 and 2 (HVR1 and HVR2). You'll remember that mitochondrial DNA has 37 rather crucial genes on it where any "typo" that occurs as the DNA is being copied could have serious consequences if the mutation is deleterious. By contrast, in those parts of the mitochondrial genome that don't code for anything, such as these two hypervariable regions, mutations can occur more freely without necessarily causing issues, meaning that these regions contain much more genetic variation. These are the sections of mitochondrial DNA that scientists began analysing for identification purposes. While it's not as precise as DNA profiling because many thousands of people will all have the same mitochondrial DNA type, it can be very helpful in a case such as this.

When the team sequenced these two regions, Prince Philip's mitochondrial DNA was found to match that of the putative remains of the tsarina and her daughters. Next they found two living female-line relatives of the tsar, descended from his maternal grandmother: a great-great-niece, Princess Xenia Cheremeteff Sfiris, and a first cousin twice removed, James Carnegie, 3rd Duke of Fife. The mitochondrial DNA from these two matched each other perfectly, and they, in turn, matched that of the tsar, except at one base where there was both a match and a mismatch.

This is because the tsar had what's known as a heteroplasmy at this position: some of the mitochondrial DNA sequences showed a T and others showed a C, his maternal relatives showing a T. Heteroplasmy is known to take place primarily through mutations occurring when the DNA is copied to make new cells in a person's lifetime, but it can be inherited from a maternal ancestor with heteroplasmy. Extremely rarely, it can come from paternal mitochondrial DNA making it into the cell. So the fact that heteroplasmy existed in the DNA sample didn't negate the match, and the probability that these were the Romanovs was still between 70 to 1 through to 840,000 to 1 in favour. But, it did sow some seeds of doubt. Incidentally, we now know that heteroplasmy is fairly common, with potentially over half of the human population having at least one heteroplasmy, albeit at a low percentage in terms of their mitochondrial DNA carrying it.

So, to be doubly sure, in 1996 the remains of the tsar's brother, Georgij, who had died in 1899, were exhumed and he was found to have exactly the same mitochondrial heteroplasmy. Given the very low chance of two people having this particular heteroplasmy if they weren't related, this pointed to the mitochondrial DNA data the researchers obtained being 130,000,000 times more likely if these were the Romanovs than if they were an unrelated family.

The case was solved in terms of identifying the tsar, tsarina and three of their daughters, but the mystery still remained as to what had happened to the two other children. In the scientific paper reporting the results, the authors conjectured that possibly the two children had been buried separately, or that they could have survived the massacre. Incidentally, there was a woman living in the U.S. who claimed to be Anastasia, saying she had managed to escape being executed, and so the fact that two of the children were missing from the Romanov family group only fuelled the idea that maybe she truly was the missing princess.

Then, in 2007, a group of amateur archaeologists, digging a mere 70 metres away from the previously discovered mass grave, came across more human remains. Skeletal evidence showed that they were the remains of two bodies, a young woman aged 15-19 and a probable male aged 12-15. DNA analysis was brought to bear and again showed that the two individuals were siblings and related to the Romanovs already identified. As an extra DNA test, Y-chromosome testing was carried out, the Y chromosome being passed from father to son, to confirm that the Y chromosome of the newly found male skeleton was indeed male and that it matched the Y chromosome of the tsar. This also then matched male-line relatives — a second cousin once removed of the tsar (third cousin of Alexei) through Tsar Nicholas I. The missing Romanov children had been found.

Adapted from The Secrets of Our DNA: How Genetics Has Changed the World by Turi King. Published by Pegasus Books. Copyright © 2026. All rights reserved.

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'> 'Links with the British royal family would eventually prove crucial': How DNA solved the 70-year mystery of what happened to the executed members ...

That status has now changed, the Wall Street Journal reported Friday (Nov. 13). The Pan American Health Organization (PAHO), which is the regional office of the World Health Organization for the Americas, has reevaluated the United States' measles elimination status and determined that it should be revoked. With this decision, the U.S. joins several other nations that have seen a local return of measles, including the U.K. and Canada.

The decision follows a series of major measles outbreaks that kicked off in January 2025. Nearly 2,300 cases were reported nationwide in 2025, and so far in 2026, almost 5,412 confirmed cases have been confirmed, although both tallies are likely undercounts.

"When January 2025 picked up, I felt like this might be the point of no return," Maimuna Majumder, a distinguished scholar in the Computational Health Informatics Program at Boston Children's Hospital, previously told Live Science. "I do want to just stress that measles elimination has always been a tenuous prospect, and it is, by design, tenuous," she added.

It takes work to keep an eliminated disease from resurging. The effort rests largely on keeping vaccination rates above a critical threshold — because the measles virus spreads so easily, at least 95% of the population needs immunity via either vaccination or past infection to prevent large outbreaks from occurring and fueling uncontrolled spread. National measles vaccination rates have been falling in recent years, with just 10 states reporting rates above the immunity threshold among kindergarteners for 2025-2026.

Experts point to several factors to explain the trend, including declining funds and staff for public health efforts and wavering public trust in vaccines and scientific expertise. The appointment of vaccine skeptic Robert F. Kennedy Jr. as health secretary and the loss of long-standing federal health leadership further fueled the trend, they say, as vaccine guidance has been changed in ways that likely sow confusion and the federal rhetoric around vaccines now frames their safety and effectiveness as open questions when they are actually well-established.

The nation's first measles-related deaths this year were reported in Pennsylvania in August, and five more have followed, according to state health officials. (Some of these deaths have not been confirmed by the federal government.) A death reported in Wisconsin and another in New York have brought the current total to eight, per states' counts.

In the U.S., about 1 to 3 out of every 1,000 measles cases results in death. Pennsylvania has recorded just over 1,500 cases, so its number of reported deaths is higher than expected, hinting that the state's true case rate has not been fully captured in the data.

In survivors, measles can cause long-term health problems, including brain damage and immune amnesia, in which the immune cells tasked with remembering past infections have their "memories" wiped.

The PAHO's meeting to reevaluate the United States' status was originally scheduled for April but was pushed to November.

To regain its measles elimination status, the U.S. must go 12 months without continuous spread of the virus.

Disclaimer: This article is for informational purposes only and is not meant to offer medical advice.

'> Measles is back in the United States, WHO authorities say

The new species were named Alouatta iroi and Alouatta matogrossensis. The adorable creatures have bushy beards, winsome expressions and bright red fur. Their identification raises the number of known howler monkey species to 16, researchers said in a statement.

"Our study shows that the Amazon still holds remarkable biological secrets, even among well-known animals such as howler monkeys," study first author Romina Batista, a biodiversity scientist at the University of Gothenburg in Sweden and the University of Salford in the U.K., said in the statement.

One of the newfound species, A. matogrossensis, is probably on the brink of extinction. The other newfound species faces threats from a planned dam on the Rio Branco River, according to the study.

In addition to identifying the new species, the study, published Oct. 30 in the journal Communications Biology, used genetic evidence to understand when howler monkeys spread out and diversified. The researchers analyzed the genomes of 11 howler monkey species living in South and Central America, combining existing DNA datasets with new genomic information from specimens in Brazilian zoological collections.

Overall, the genetic data confirmed that howler monkeys diverged from close relatives between 19 million and 13.5 million years ago. But the analysis changed the picture of more recent evolution.

For instance, the team argued that the Tapajós red-handed howler (A. tapajozensis) and the Amazonian black howler (A. nigerrima) are not as closely related as scientists previously thought. The researchers also said that the Trinidad howler (A. insulanus), whose status has been unclear, should be confirmed as a separate species.

"This discovery comes at a critical time, as increasing deforestation, climate change and habitat loss threaten many Amazonian species before they are fully understood or even discovered by science," study co-author Jean Boubli, a professor and chair of primate ecology and evolution at the University of Salford in the U.K., said in the statement.

The scientists found that natural barriers such as the Amazon River, the Xingu River and the Branco River drove many howler monkeys to develop separately. Researchers believe that howler monkeys can swim across small waterways, but big rivers block groups from mixing, which led to different traits and species evolving over time. Natural barriers are a common reason why species emerge in the Amazon, the researchers noted in the study.

Primates Quiz: Go ape and test your knowledge on our closest relatives

'> Scientists discover two adorable species of howler monkey in the Amazon — and they're already endangered

The scans revealed that Bentham was missing many teeth and had advanced arthritis in his lower jaw when he died of natural causes at the age of 84. During the scanning process, project leader Tannis Davidson, curator of UCL's Grant Museum of Zoology, saw how thin the jawbone had become. "He must have been in excruciating pain," she told Live Science.

Bentham's utilitarian philosophy inspired UCL's founders; it was only the third university in England, after Oxford and Cambridge, which was founded as London University in 1826 and opened to students in 1828.

As a young man, Bentham had declared that he would donate his body to science after his death. This was a radical idea at the time; in the U.K., dissection after death was looked down upon, even if it was for scientific purposes, and it was reserved for the worst criminals. After Bentham died in 1832, his remains were fashioned into an auto-icon — a supposed replica of himself — to memorialize him in the way a tombstone might, Davidson said.

Except for brief visits across Europe and to the Met Breuer in New York City, this auto-icon has been in a display case at UCL since the 1850s, where it can be seen by students as they pass by.

Brainless auto-icon

To make the auto-icon (which is not a mummy), Bentham's body was dissected and studied. Then, his skeleton was dressed in his clothes, which were padded with straw. His severed head was badly disfigured during an attempt to preserve it with sulfuric acid, so a wax reconstruction based on paintings and death masks was attached to the body.

Bentham's real head was displayed at the feet of the clothed skeleton that had a lifelike wax head; the real head's eyes were replaced with highly detailed glass eyes, which can be seen in the scans. According to UCL lore, the real head was stolen in 1975 and held ransom for a few days by rivals from King's College London, after which it was locked away.

Davidson explained that Bentham had coined the term "auto-icon" to mean "self-representation" and was setting an example for others. "He imagined a future where people were making auto-icons to keep their dead relatives around," she said.

The CT scans of the real head show that Bentham had dental damage and jaw arthritis, and that his brain had been removed before it was preserved—although some of his dura mater, a layer of connective tissue that covers the brain and spinal cord, was preserved. Davidson said the brain extraction was done to keep with Bentham's instructions that his head be mummified in the same way as Māori heads, which had their brains removed. The scanning process is shown in a short film called "Bentham Revealed."

"Godless" philosopher

Bentham wrote about his dental problems several times, Davidson said, but it is not clear if he understood that he also had severe arthritis in his lower jaw, which must have made the problems with his teeth much more painful. In addition, modern ideas about cleaning teeth had not been established by Bentham's time. "Dentistry 200 years ago was a very different kettle of fish than it is today," Davidson said.

Bentham was a polymath who hoped to improve the lives of ordinary people through social reform. He wrote extensively about subjects as varied as law, economics, education and animal rights, and he believed that society could be engineered to produce better outcomes through legislation and the objective measurement of "utility."

His most famous idea was the panopticon in 1791, a ring-shaped prison with one warden to watch all of the prisoners, which he proposed as a humane alternative to Australia's penal colonies. Today, however, it is a symbol of state control and surveillance. Bentham also invented a "felicific calculus" to numerically assess the benefits and drawbacks of any given action, based on variables like its intensity, duration, certainty, purity and extent.

Bentham's philosophy put him at odds with the established Church of England; he called himself an "unbeliever," while critics called him "godless."

This rift with the church may have played a part in Bentham's wishes for his remains. Davidson suggested that the auto-icon may have been a means for Bentham to avoid being buried with traditional Anglican rites. "Maybe this was a way he could 'stick it to them' a little bit," she said.

'> 'Godless' founder of utilitarianism had severe dental problems and was in 'excruciating pain,' CT scans of his severed head reveal