While mitochondrial function has long been linked to longevity and mitochondrial dysfunction has been tied to disease, Jonathan offers fresh insight into that dynamic, said study co-author Stephen Clark, chief scientist of the Kallel Foundation, a nonprofit in Nashville researching drug targets to promote human longevity.

Clark and colleagues published their findings Wednesday (Oct. 7) in the journal Science Advances.

Decoding Jonathan's secrets to long life

Nearly a decade ago, the researchers enlisted Joe Hollins, the vet tasked with Jonathan's care, to collect samples from the record-setting animal. Island authorities forbade the vet from drawing the tortoise's blood, fearing the risk of an infection.

"I didn't want to be the doctor that killed Jonathan," Clark told Live Science. Hollins collected samples via cheek swab instead.

When the samples arrived in the U.S., the researchers sequenced them, but when their computers kept crashing, they discovered that the DNA had been isolated from bacteria in Jonathan's mouth rather than the tortoise's own cells.

Clark "had to go back and beg" for permission to collect more data, he said. The vet then sent cheek scrape samples, which are collected with a slightly different tool than cheek swabs. This time, the DNA was in fact from Jonathan.

The DNA isolated from those cheek tissue samples was more fragmented than it would have been in a blood sample, so the researchers filled in the gaps using an existing reference genome from a 36-year-old Aldabra tortoise named Tank. They also compared Jonathan's DNA to that of a Galápagos tortoise (Chelonoidis abingdoni) named Lonesome George, who was believed to be over 100 years old at the time of his death in 2012.

The team found that, compared to Tank and Lonesome George, Jonathan carried 287 unique variants of genes that had previously been linked to aging-related pathways. These included genes involved in DNA repair and the function of telomeres — the protective tips at the end of chromosomes that tend to shorten with age.

These pathways are also related to aging processes in humans, highlighting a "broader signature of aging" across species, Greer Dolby, an assistant professor of biology at The University of Alabama at Birmingham, who was not involved with the study, told Live Science.

The researchers also looked at epigenetic changes, including DNA methylation, which is when a chemical tag called a methyl group binds the DNA. Certain patterns of DNA methylation can function as a "clock" in that they reflect an organism's biological age; scientists have recently harnessed these patterns in the study of human aging. In this case, the team compared the DNA methylation across Jonathan's genome to that of young and old Aldabra tortoises.

The methylation patterns were more disordered in the older tortoises, reflecting random changes acquired over time, the researchers found. Scientists call this phenomenon "methylation entropy." For most genes, Jonathan's DNA methylation patterns were more disordered than those of the young tortoises. But in a suite of genes tied to mitochondrial function — specifically the bits of those genes that switch them "on" — Jonathan had more organized methylation patterns. That might keep expression of these genes consistent over time, the researchers theorized.

Mitochondria produce energy that cells need to function properly, repair themselves and reduce further damage to DNA. "Keeping the entropy low in these mitochondrial genes, or keeping pristine mitochondria, is likely to be a contributor to longevity," Clark said.

However, the authors couldn't determine a causal relationship — they didn't run any tests that could definitively prove that Jonathon's lack of entropy in these genes explains his long life. Clark argued that additional experiments on a blood sample from Jonathan could offer a more comprehensive view of his genome.

Jonathan's full genetic profile can't be known until after the tortoise's death, when researchers can collect DNA from more tissues, said Vincent Lynch, a professor of biology at the University at Buffalo, who was not involved with the study.

"Some organs are more susceptible to different diseases of old age than other ones, and that happens because mutations accumulate over time," he told Live Science. "We would ideally like to know what those mutations are in those specific tissues."

Furthermore, Lynch questioned whether entropy was a useful characterization of age-related DNA methylation patterns, as methylation can be unpredictable. That said, he agreed that the genes flagged in the study offer helpful data for future work on longevity.

More experiments are needed to determine whether these mitochondrial genes actually play a role in longevity across all Aldabra tortoises, let alone in other animals, or if Jonathan is just an outlier.

"Maybe Jonathan is just really good at being old," Lynch said.

'> Scientists discover the genetic secrets that may have helped Jonathan the tortoise live to 194 years old Zhe-Xi Luo, a paleontologist at the University of Chicago, told Live Science. "The back half of this animal is very much like a platypus. As are the limbs, which would be capable of swimming or digging tunnels in river banks."

But the teeth "are definitely not like a platypus," Luo said. It possessed robust canines and shearing cheek-teeth that would cut and chew meat in a different way from modern carnivorous mammals. "It's a predator with gigantic and very specialized canines," Luo said. "So, it's partly otter-like and partly platypus-like."

A revealing fossil

Tiny bits of vertebrate bones found in what would have been the animal's stomach and the surrounding fossil beds hint that M. sungei dined on salamanders, Luo said.

He added that M. sungei may have sheltered in burrows on land in the temperate plant-filled climate, and hunted in lakes and rivers for fish and invertebrates.

Another notable aspect of the fossil is its throat. Modern mammals, including humans, have hyoid bones in the throat arranged in a "U"-shaped saddle. These help us use throat muscles to swallow chewed food one chunk at a time, instead of gulping down huge bites or whole prey. The structures also enable babies to suckle their mother's milk.

M. sungei seems to have had the apparatus needed to do this, study co-author Thomas Martin, a paleontologist at the University of Bonn in Germany, told Live Science.

"This is an incredibly important evolutionary innovation," Luo said, adding that this capability is one of the things that helped early mammals diversify into carnivores, insectivores, herbivores or omnivores to take advantage of all sorts of foods.

Finding this in M. sungei suggests that the apparatus needed for suckling milk and swallowing had already evolved by the Middle Jurassic (around 174 million to 164 million years ago), Martin said.

This is before marsupials like kangaroos and placental mammals like primates and bears are thought to have diverged from each other 160 million years ago, after descending from an egg-laying common ancestor that lived approximately 180 million years ago.

"Now we push the history of it back to before the split of modern marsupials and modern eutherian [placental] mammals," Luo said.

"Neonatal suckling behaviour was previously thought of as being a hallmark of advanced mammals, but it now appears to have evolved well before then, in the common ancestor of docodontans and mammals at least 165 million years ago," said Sue Hand, a vertebrate paleontologist at the University of New South Wales in Australia who wasn’t involved in the study.

M. sungei is from an extinct lineage of docodonts, which are relatives of mammals from the dinosaur-dominated Jurassic and Cretaceous periods, living between about 200 million and 120 million years ago.

Docodonts adapted to a wide variety of habitats. For example, there was the Jurassic tree-dwelling shrew-like docodont called Microdocodon gracilis, and Docofossor brachydactylus, a tunnel-digger with shovel-like paws. Luo was also part of the team that described a semiaquatic "Jurassic beaver", Castorocauda lutrasimilis, which lived 164 million years ago.

"It seems that an aquatic lifestyle arose often in early mammal-like species," said Tim Flannery, a mammalogist at the Australian Museum Research institute who wasn't involved in the work.

If anything, the newly described "spectacular fossil" shows that docodonts were wide-ranging during the dinosaur age, Hand told Live Science in an email.

"This very detailed study adds to accumulating evidence that mammaliaforms occupied a wide range of ecological niches long before the evolution of living mammals," Hand said.

'> 'It looks like a chimera' — 168 million years ago, a strange platypus-like mammal relative lived in China alongside dinosaurs solar system.

The mysterious floating mass, dubbed the Arsia Mons Elongated Cloud (AMEC), frequently emerges above Arsia Mons, a 12-mile-tall (20 km) extinct volcano located in the Tharsis region, just south of the Red Planet's equator. The water vapor cloud was first spotted in 2018 by the European Space Agency's Mars Express orbiter and has since appeared nearly every morning throughout Mars' spring and summer, when increased solar radiation triggers strong surface winds. But it lasts only a few hours each day, before fully evaporating.

The AMEC can stretch up to 1,100 miles (1,800 km) long, around one-twelfth of Mars' circumference. For context, that is roughly twice the length of the U.K. or the distance between New York City and Miami.

Although the Red Planet is no stranger to giant dust clouds and occasional "iridescent streaks" of carbon dioxide, it is almost completely devoid of atmospheric water vapor. That makes it extremely rare for puffy, Earth-like clouds to form there, let alone ones so vast. As a result, scientists have struggled to explain this whacky weather.

But in a new study published Wednesday (Oct. 7) in the journal Nature Geoscience, researchers used Mars Express data to create new simulations in an effort to finally explain the AMEC. Initially, the team struggled to recreate the puzzling phenomenon. But when they abandoned traditional meteorological principles in favor of a more out-of-the-box explanation, they were eventually successful.

"To create the AMEC in our modelling, we found that we needed to include some exotic physics … physics that, while included in textbooks, is treated as theoretical and usually thought not to happen in nature," study first author Jorge Hernández-Bernal, a planetary scientist at the University of the Basque Country in Spain who was affiliated with Sorbonne University in Paris at the time of the study, said in a statement. "Once we included this physics in our simulations, the AMEC emerged just as we hoped."

"Wholly unexpected"

The AMEC is an orographic cloud, meaning it forms as strong winds push water vapor up and over a raised structure, such as a mountain. Similar clouds also exist on Earth, including the "Levanter" cloud, which occasionally forms above the Rock of Gibraltar in southern Europe. However, the Martian equivalent cannot be explained by the same processes that occur on our planet.

On Earth, clouds form via a process called heterogeneous nucleation, in which moist air cools and condenses into ice crystals that form around tiny atmospheric particles, such as dust, salt, pollen or soot. But while Mars has plenty of atmospheric dust, that's not what's happening there.

"For the AMEC, it seems that cloud formation takes place without needing any of this 'stuff' [in the air]," said Hernández-Bernal, who has been studying the AMEC for the past six years. "Water vapour turns directly into icy cloud particles without any middle step. It's akin to droplets of condensation appearing in the middle of a room, rather than on a window."

The researchers call this "homogeneous nucleation" and say it has never been seen before in a planetary atmosphere. "It's wholly unexpected," Hernández-Bernal added.

Other scientists previously predicted that homogeneous nucleation could occur in Earth's upper atmosphere or in the skies above Venus. However, this has been deemed highly unlikely because it requires humidity levels roughly 100,000 times greater than those on our planet's surface.

Given that modern-day Mars is almost completely devoid of water, it may seem unlikely that its humidity levels could reach such lofty heights. However, the Mars Express data tells a different story.

As wind rises up the slopes of Arsia Mons, which is more than twice as tall as Mount Everest, it creates a powerful wave that shoots air into the upper atmosphere at tremendous speed. The researchers calculated that the temperature of this air can drop by up to 54 degrees Fahrenheit (30 degrees Celsius) in just 10 minutes. This not only makes it easy to freeze but also greatly increases the humidity within the wave, allowing homogeneous nucleation to take place, the simulations show.

So where does all this water come from? Some of it is already in the atmosphere, but some likely originates at the summit of Arsia Mons, which is covered with a thick layer of frost, the researchers suggested.

"A big success"

The new simulations mark a big step forward in our understanding of the AMEC and wider Martian meteorology.

"We don't have nearly as much information about Mars' atmosphere as we do about Earth's, so reproducing the AMEC to this degree is a big success for the model," Hernández-Bernal said.

The findings would not have been possible without the Mars Express orbiter, which used three instruments — the Visual Monitoring Camera, the High Resolution Stereo Camera and the OMEGA instrument — to map out how the AMEC takes shape and evolves every day. It is also one of the only Mars spacecraft that can see Arsia Mons in daylight.

"Mars Express discovered the AMEC, has followed up and monitored it for years, and is now helping reveal the secrets of its formation," Colin Wilson, the project scientist for Mars Express, who was not involved in the new study, said in the statement.

The discovery is also a reminder that, despite sharing the same basic principles, weather systems do not behave the same on other worlds as they do on Earth, which could have big implications for solar system exploration and the hunt for extraterrestrial life on distant exoplanets.

"While clouds on Earth and Mars seem to be governed by the same 'rules', understanding this exotic Martian cloud required exotic physics — and this may be true elsewhere in the cosmos," Wilson said.

'> 1,000-mile-long cloud that forms and vanishes on Mars every day obeys 'exotic physics' never seen on Earth

The comments reflected this majority, as one reader wrote, "We're on the edge of an area at risk for grass fires, so we bought/stocked an RV as an emergency bugout vehicle. Felt extreme initially, less so as time goes by. Gives us 3-5 days of margin before we need to resupply, with food, water and first aid for people and dogs."

Another commenter responded to the rest of the comments, writing, "This is just the begining [sic]. Get a greenhouse, plant food, learn to harvest water, build an outside toilet (for later), learn to be self sufficient. trade with your neighbors. Plant fruit trees, get solar panels and an electric transporation (bike, car whatever). Keep a de humidifier in your home. it's back to the 1930ie[s]."

Do you agree with these readers? Let us know in the comments section.

'> 'We stocked an RV as an emergency bugout vehicle': Readers share how prepared they are for a disaster

The unnamed exoplanet was spotted circling the white dwarf HS 0209+0832, which is located roughly 270 light-years from Earth. White dwarfs are stellar remnants, sometimes dubbed "zombie stars," that form from the leftovers of massive red giants that run out of fuel before eventually collapsing into shriveled husks. HS 0209+0832 is a particularly young white dwarf, still burning at around 63,000 degrees Fahrenheit (35,000 degrees Celsius), which suggests it made this transition within the past few million years.

Scientists previously discovered some surprising heavy elements within the visible spectrum of HS 0209+0832, which was first captured by the Hubble Space Telescope in the late 1990s. These elements ‪—‬ which included aluminium, titanium and nickel ‪—‬ are not normally found inside white dwarfs, so their presence suggested that something unusual was going on. But until now, there was not enough data to figure out what.

In the new study, published Oct. 5 in the journal Nature Astronomy, researchers took a closer look at HS 0209+0832. Using some of Hubble's updated instruments and data from other observatories, the team captured a more detailed spectrum of the stellar zombie. This revealed a high concentration of additional heavy elements, including zinc and copper, as well as niobium, which has never been seen in a white dwarf before.

The researchers think these out-of-place elements were created during the death throes of the former red giant and later coalesced into a "second-generation" planet around the newly forged white dwarf. They suspect the atmosphere of this hypothetical planet is being stripped by the white dwarf's stellar winds, causing the rare elements to fall back onto the zombie star.

Follow-up observations then revealed a recurring dip in the brightness of HS 0209+0832, suggesting that an exoplanet was repeatedly passing in front of the undead star. Based on the alien world's orbit, which lasts approximately 4.4 Earth days, and the duration of its transits in front of the star, the team predicted that the planet is roughly the size of Jupiter. (Its close proximity to the white dwarf also supports the hypothesis that its atmosphere is being stripped away.)

"Second-generation planets are worlds that form out of the material a star casts off as it dies," study first author Jamie Williams, a doctoral candidate in astronomy and astrophysics at the University of Warwick in the U.K., said in a statement. "They're incredibly rare, and finding one around a white dwarf was completely unexpected. It's a bit like finding a planet that has risen from the ashes of the very star it once orbited."

"Completely unexpected"

This is not the first time astronomers have spotted an exoplanet around a white dwarf. For example, in 2019, some of the authors of the new study previously spotted an alien world surrounding the white dwarf WDJ0914+1914. However, in that case, they were confident that it was a first-generation world that somehow survived its star's fiery end.

But the heavy elements that seem to be falling onto HS 0209+0832 — and the relative lack of other elements common in first-generation planets, such as silicon and iron — suggest that's not what's happened for this recently detected world.

"This pattern of elements is a telltale sign of the 's-process,' a nuclear reaction that builds heavy elements inside dying stars during their bloated red giant phase," study co-author Nicholas Stone, an astronomer at the University of Wisconsin-Madison, said in the statement. "It's a chemical signature no ordinary, 'first-generation' planet should carry, which told us that this new planet was something different."

Instead, the newly detected exoplanet likely formed directly from the material that was shed by the dying red giant after it expanded and before it collapsed in on itself.

Similar phoenix planets have been spotted alongside other stellar remnants, such as pulsars, which form when stars explode as supernovas. However, until now, such worlds have never been seen around a white dwarf.

Rising from the ashes

"What's remarkable about the planet around HS 0209+0832 is that this isn't a planet from somewhere else, or a survivor from the system's birth, it looks like it was built from the very material its own star cast off as it died," study co-author Boris Gänsicke, an astrophysicist at the University of Warwick who also helped to discover the exoplanet around WDJ0914+1914 in 2019, said in the statement. "In a sense, this system has given birth to a new world using the foundations of the old one."

HS 0209+0832 may have once harbored other exoplanets when it was a red giant. But if they existed, these alien worlds likely perished in flames as the dying star ballooned — similar to what experts think will happen to Earth when the sun runs out of fuel and transitions into a red giant in around 5 billion years.

Once the sun has finished bulging, it will turn into a white dwarf too. The new discovery hints that our star could also host brand-new worlds after it has transformed, creating a sort of solar system 2.0.

"Finding this one example raises the question of how many more might be out there and might our own solar system host a second-generation planet formed from the ashes of our sun," Gänsicke said.

However, more work is required to figure out exactly how the newfound exoplanet formed and, as a result, how likely this scenario is. The researchers suspect that another object, such as a lost stellar sibling, may have been required to create the new world.

"Forming the protoplanetary disc in this situation is not easy and helps explain why these planets are so rare," Williams said. "To form a disc of material necessary to birth a planet, HS 0209+0832 likely required a companion star that pulled the ejected material back into orbit, rather than letting it escape."

'> 'Completely unexpected': Astronomers spy never-before-seen 'phoenix planet' rising from the ashes of a dead star