Forests - the green frame of the planet

08/02/2023

08/02/2023

08/02/2023

Sky Light This photo is a single frame from a timelapse that I did earlier this year. The camera was out in the storm, not me. The image is as captured.
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08/02/2023

Flying Cheetah 👀 Beautiful photo of a cheetah at top speed.
📸 Photography by © (Jose Fragozo). [IG]

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08/02/2023

Is our fundamental reality continuous or is it chopped up into tiny, discrete bits?

Asked another way, is space-time smooth or chunky? The question cuts to the heart of the most fundamental theories of physics, linking together the way space and time intersect with the material of our everyday existence.

However, experimentally testing the nature of space and time has been impossible, because of the extreme energies needed to probe such tiny scales in the universe. That is — until now. A team of astronomers has proposed an ambitious new plan to use a fleet of tiny spacecraft to detect subtle changes in the speed of light, a hallmark of some of the most mind-bending theories of the cosmos. If space and time are indeed broken up into little bits, the research could pave the way for a completely new understanding of reality.

Related: The 18 Biggest Unsolved Mysteries in Physics

Chunky vs. smooth
The question of "what is space and time?" goes back thousands of years, and our modern understanding rests on two strangely incompatible pillars: quantum mechanics and Einstein's theory of general relativity.

In general relativity, space and time are woven together into the unified fabric of space-time, the four-dimensional stage that underpins our universe. This space-time is continuous, which means that there are no gaps anywhere; it's all a smooth texture. Space-time isn't just a platform for us to act our parts, however; it's also a player too: The bending and warping of space-time gives us our experience of gravity.

Related: 8 Ways You Can See Einstein's Theory of Relativity in Real Life

In the opposite corner, a set of rules called quantum mechanics governs the interactions of the very tiny things in the universe. Quantum mechanics rests on the idea that not much of our everyday experience is smooth and continuous, but chunky. In other words, it's quantized. Energy, momentum, spin and so many other properties of matter come in only discrete little packets.

What's more, quantum mechanics itself also splits itself into two camps. On one hand, we have the familiar particles of our everyday existence, such as electrons and protons, that interact and do other interesting things. These are obviously very chunky, as they're discrete "things." On the other hand, we have the quantum fields. In the subatomic world, each kind of particle has its own field that spreads throughout space-time; when we think of particles, we think of little vibrations in their fields, which in turn interact with other particles, and do some other interesting things. The fields are understandably very smooth.

Bits of time and space
So, we have some smooth pictures of our universe and some chunky ones. When it comes to space-time itself, we can easily imagine extending the concepts of quantum mechanics all the way to their logical conclusion, and ruling that space and time are discrete: The very fabric of reality is divided up like pixels on a computer screen, and what we experience as smooth, continuous movement is nothing but a grid of discrete pixels at the tiniest of scales.

Related: The Illusion of Time: What's Real?

Many theories of merging together quantum mechanics and general relativity, like string theory and loop quantum gravity, predict some form of discrete space-time (although the precise predictions, interpretations and implications of that chunkiness are still poorly understood). If we could find evidence for discrete space-time, it would not only completely rewrite our understanding of reality, but also open the door to a revolution in physics.

This discreteness can reveal itself only in the most subtle ways; otherwise we would've spotted it by now. Various theories have predicted that if space-time were indeed chunky, then the speed of light may not be entirely constant — it may shift ever so slightly depending on the energy of that light. Higher energy light has a shorter wavelength, and when the wavelength becomes small enough, it can "see" the chunkiness of spacetime. Imagine walking down sidewalk: with big feet you don't notice any small cracks or bumps, but if you had microscopic feet you would trip over every little imperfection, slowing you down. But this shift is incredibly tiny; if space-time is discrete, it's on a scale more than a billion times smaller than what we can currently probe in our most powerful experiments.

A quest for the grail
Enter GrailQuest: the Gamma-ray Astronomy International Laboratory for Quantum Exploration of Space-Time. A team of astronomers submitted a proposal for this mission in response to a call for new space-time-hunting ideas from the European Space Agency (ESA). Their proposal is detailed in the arXiv database, meaning that it hasn't yet been reviewed by peers in the field.

Here's the scoop: In order to see if the speed of light changes with different energies, we need to collect a huge amount of the highest-energy light in the universe, and GrailQuest hopes to do just that.

GrailQuest consists of a fleet of small, simple spacecraft (the exact number varies, from just a few dozen if the satellites are larger to well over a few thousand if they're smaller) to constantly monitor the sky for gamma-ray bursts. These are some of the most powerful explosions in the universe. Like their name suggests, these bursts release copious amounts of high-energy photons, a.k.a. gamma rays. These gamma rays travel across billions of years before reaching the fleet of spacecraft, which record the energy of the gamma rays and the differences in timings as the burst washes over the fleet.

With enough accuracy, GrailQuest might be able to reveal if space-time is discrete. At least, it has the right setup: It's examining the highest-energy light (which is affected the most in theories that predict that space-time is chunky); the gamma rays have been traveling for billions of light-years (allowing the effect to build up over time); and the spacecraft are simple enough to produce en masse (so the entire fleet can see as many events as possible, all across the sky).

How would our conceptions of reality change if GrailQuest were to find evidence for the discreteness of space-time? It's impossible to say — our current theories are all over the map when it comes to implications. But no matter what, we're going to have to wait. This round of ESA proposals is for launches sometime between 2035 and 2050. While we're waiting, we can debate if the time elapsed between now and then is fundamentally smooth or chunky.

08/02/2023

For a multitude of reasons, great white sharks should be considered nature's ocean-dwelling superheroes — they're big and strong, live long lives, can heal their wounds remarkably fast, and it's even likely that they rarely get cancer. But how is it possible that these ancient giants have so many superhero-like traits? Scientists have now taken a major step toward answering that question by decoding the entire genome of the great white shark.

An international team of researchers led by scientists at the Save Our Seas Foundation Shark Research Center and the Guy Harvey Research Institute at Nova Southeastern University in Florida sequenced the genome of the great white shark (Carcharodon carcharias) and compared it with the genomes of several other vertebrate species. The team discovered a wealth of unusual genetic characteristics that might explain why white sharks are the superheroes (or supervillains, if you're a plump sea lion) of the sea. Their study was published online on Monday (Feb. 18) in the journal Proceedings of the National Academy of Sciences.

Genetic stability is key
Sequencing the great white shark genome was no small task — the genome consisted of 4.63 billion base pairs (the nitrogen-containing molecules that make up the "rungs" of the DNA ladder), which is about 1.5 times the size of the human genome. "It's quite an impressive effort," said Dovi Kacev, a marine molecular ecologist and researcher at the National Marine Fisheries Services Southwest Fisheries Science Center in California, who was not involved with the study. [Image Gallery: Great White Sharks]

Nearly 60 percent of the white shark genome consisted of repeated genetic sequences, which is similar to what's seen in the human genome. What's special about the white shark genome was that many of those repeated regions are codes for a special group of genes known as LINEs.

"These [LINEs] make copies of themselves and then reinsert randomly in various locations in the genome, and in the process they make double-stranded breaks in the DNA that need to be repaired," said Michael Stanhope, an evolutionary biologist at Cornell University in New York. Stanhope co-led the study with Nicholas Marra and Mahmood Shivji, conservation biologists at Nova Southeastern University.

Those frequent breaks in the DNA make the genome unstable, which typically leads to a higher risk of problem-causing genetic mutations that can eventually lead to cancer. But white sharks seem to have evolved a way to avoid such genomic instability.

The researchers found that the white shark genome contained a lot of genes responsible for maintaining genetic stability — things like DNA-repair genes and tumor-suppressing genes. And when the researchers compared the white shark's stability genes with analogous genes in other vertebrates, they found small changes in the gene sequence that suggest a specific pattern of evolutionary adaptation for these genes in white sharks.

"Think of it as fine-tuning the role of these genes in maintaining genome stability in the white shark," Stanhope said.

People have speculated that sharks have a much lower rate of cancer than other animals, but "there's not a lot of real data to say that with certainty," Kacev said. Nonetheless, the abundant presence of specially adapted stability genes could explain the potential cancer resistance.

"If you want to prevent cancer, you need to maintain the stability of your genome," Stanhope said, which means avoiding genetic mutations. An accumulation of excess mutations leads to cancer, but the shark genome seems specifically designed to prevent that. "These are things we would have to test in the lab, though, to really know," he said.

Stanhope also cautioned that while white sharks might have a genetic adaptation to prevent them from getting cancer, that does not mean that consuming shark products could prevent a human from getting cancer, despite what proponents of "alternative medicine" may claim.

And their other special abilities …
Genetics may also explain another one of the white shark's superpowers: the ability to heal quickly. The team discovered several white shark genes that are known to play important roles in vertebrate wound-healing processes. And, similar to the stability genes, the wound-healing genes in the white shark were under the same kind of positive evolutionary selection pressures, meaning there's a tendency for the number of these beneficial traits to increase.

"We also found an enrichment of genes for both wound healing and genome stability genes in the white shark compared to other vertebrates," Stanhope said. In other words, the white shark genome has a higher proportion of these types of genes compared with what's seen in other vertebrate genomes.

While the team discovered a number of genes that may be responsible for many of the great white's super-shark abilities, there was one characteristic that wasn't clearly accounted for by the genome: the shark's sensitive sniffer.

Sharks are known for having a keen sense of smell, so the researchers expected to find numerous olfactory receptor (OR) genes, which are the genes responsible for the effective schnozes of other vertebrates. But the white shark genome contained exceptionally few of these genes. What the researchers found instead was another category of genes, called vomeronasal genes. These genes can also be involved in the perception of smell, but they aren't normally as abundant as OR genes, Stanhope said. In the white shark genome, however, there are more than dozen vomeronasal genes, so the researchers suggested that maybe those genes drive smell perception in the white shark.

"We're still at a point here where we're scratching the surface, but having this genome sequence gives us a starting point for addressing these questions in more detail," Kacev said. This research will undoubtedly help answer questions about other species, too, he added. "Understanding the genome of the white shark is not only important for the white shark, but it's a scaffold, or jumping-off point to understand related species."

Great white sharks are one of the world's most well-recognized marine creatures, but their populations are struggling as people continue to hunt them out of fear and greed. "People have these images of [white sharks] that are depicted in movies and TV shows as being these killing machines," Kacev said. Yet, the reality is that humans kill far more sharks than sharks kill humans.

"Humans kill many, many millions of sharks every year across the world for silly, fake medicine reasons; for shark fin soup and all sorts of reasons that are just tragic, really," Stanhope said. The researchers hope their study helps more people realize how special these ancient vertebrates are.

"I hope that people recognize the remarkable, biological adaptations of these animals and as a consequence, have a greater appreciation for them," Stanhope said.

06/02/2023

The animal bones at Umm el-Marra were thought to be from kungas because their teeth had marks from bit harnesses and wear patterns that showed they had been fed, rather than left to graze. (Image credit: Glenn Schwartz/Johns Hopkins University)
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Mesopotamians were using hybrids of domesticated donkeys and wild asses to pull their war wagons 4,500 years ago — at least 500 years before horses were bred for the purpose, a new study reveals.

The analysis of ancient DNA from animal bones unearthed in northern Syria resolves a long-standing question of just what type of animals were the "kungas" described in ancient sources as pulling war wagons.

"From the skeletons, we knew they were equids [horse-like animals], but they did not fit the measurements of donkeys and they did not fit the measurements of Syrian wild asses," said study co-author Eva-Maria Geigl, a genomicist at the Institut Jacques Monod in Paris. "So they were somehow different, but it was not clear what the difference was."

The new study shows, however, that kungas were strong, fast and yet sterile hybrids of a female domestic donkey and a male Syrian wild ass, or hemione — an equid species native to the region.

Related: Horned figures from cult of a Mesopotamian moon god discovered in biblical-era fort

Ancient records mentioned kungas as highly prized and very expensive beasts, which could be explained by the rather difficult process of breeding them, Geigl said.

Because each kunga was sterile, like many hybrid animals such as mules, they had to be produced by mating a female domesticated donkey with a male wild ass, which had to be captured, she said.

That was an especially difficult task because wild asses could run faster than donkeys and even kungas, and were impossible to tame, she said.

"They really bio-engineered these hybrids," Geigl told Live Science. "There were the earliest hybrids ever, as far as we know, and they had to do that each time for each kunga that was produced — so this explains why they were so valuable."

War donkeys
Image 1 of 2
The war panel from the "Standard of Ur," a 4500-year-old Sumerian mosaic now in the British Museum, shows teams of kungas drawing four-wheeled wall wagons.
The war panel from the "Standard of Ur," a 4500-year-old Sumerian mosaic now in the British Museum, shows teams of kungas drawing four-wheeled wall wagons.(Image credit: Thierry Grange/IJM/CNRS-Université de Paris)
This carved stone panel from the Assyrian capital Nineveh shows two men leading an untamable wild ass they have captured, probably for breeding kungas.
This carved stone panel from the Assyrian capital Nineveh shows two men leading an untamable wild ass they have captured, probably for breeding kungas.(Image credit: Eva-Maria Geigl/IJM/CNRS-Université de Paris)
Kungas are mentioned in several ancient texts in cuneiform on clay tablets from Mesopotamia, and they are portrayed drawing four-wheeled war wagons on the famous "Standard of Ur," a Sumerian mosaic from about 4,500 years ago that's now on display at the British Museum in London.

Archaeologists had suspected that they were some sort of hybrid donkey, but they didn't know the equid it was hybridized with, Geigl said.

Some experts thought Syrian wild asses were much too small — smaller than donkeys — to be bred to produce kungas, she said.

Related: Mustangs: Facts about America's 'wild' horses

The bones of the kungas were excavated about 10 years ago from a burial mound at Tell Umm el-Marra in northern Syria by University of Pennsylvania archaeologist Jill Weber.

The bones of the kungas were excavated about 10 years ago from a burial mound at Tell Umm el-Marra in northern Syria by University of Pennsylvania archaeologist Jill Weber. (Image credit: Glenn Schwartz/Johns Hopkins University)
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The species is now extinct, and the last Syrian wild ass — not much more than a meter (3 feet) tall — died in 1927 at the world's oldest zoo, the Tiergarten Schönbrunn(opens in new tab) in Vienna in Austria; its remains are now preserved in that city's natural history museum.

In the new study, the researchers compared the genome from the bones of the last Syrian wild ass from Vienna with the genome from the 11,000-year-old bones of a wild ass unearthed at the archaeological site of Göbekli Tepe, in what is now southeastern Turkey.

That comparison showed both animals were the same species, but the ancient wild ass was much larger, Geigl said. That suggested that the Syrian wild ass species had become much smaller in recent times than it had been in antiquity, probably due to environmental pressures such as hunting, she said.

06/02/2023

Animals carry "mutational clocks" in their cells that dictate how quickly their DNA picks up mutations. And across species, animals tend to die once they've hit a certain number of mutations, new research finds.

It turns out that, in long-lived mammals like humans, these mutational clocks tick slower than they do in short-lived mammals like mice, meaning humans reach that threshold number of mutations at a later age than mice do. This discovery, the researchers said, could help solve a long-standing mystery in biology.

This mystery, known as Peto's paradox, describes a perplexing phenomenon that has defied explanation since the 1970s. At that time, scientists knew that animal cells accrued mutations in their DNA over time, and that as the number of mutations increased, so too did the risk of those cells turning cancerous. On paper, this suggests that the world's longest-living and largest animals should face the highest risk of cancer, because the chance of picking up cancer-causing mutations increases over time and as the total number of cells in an organism goes up.

But oddly enough, large, long-lived animals develop cancer at similar rates as tiny, short-lived creatures — this is Peto's paradox. Now, in a new study, published April 13 in the journal Nature(opens in new tab), scientists offer a partial potential solution to this puzzle: They discovered that short- and long-lived mammals both accumulate a similar number of genetic mutations over their lifespans, but the long-lived animals do so at a far slower rate.

"I was really surprised" at the strength of the relationship between lifespan and mutation rate in different species, said Alex Cagan, a staff scientist at the Wellcome Sanger Institute in England and first author of the study. The study results help explain one aspect of Peto's paradox, by showing that having a lengthy lifespan doesn't put animals at higher risk of cancer-causing mutations. However, the authors didn't find a strong link between animals' body masses and their mutational clocks, so their results don't address the question of why big animals don't have high rates of cancer.

Related: Scientists discover 4 distinct patterns of aging

The results do support the theory that animals age, at least in part, due to the build-up of mutations in their cells over time — although the study doesn't reveal exactly how the mutations contribute to the aging process, Cagan said.

"Based on our results, yes, you can tell a mammal is close to the end of its species' lifespan when it has [approximately] 3,200 mutations in its colonic epithelial stem cells," which was the specific population of cells that the team analyzed. "But we don't think that it's because at 3,201, the animal will drop dead from mutation overload," Cagan said. Rather, the authors think that the relationship between animals' mutational clocks and aging might be a bit more nuanced.

04/02/2023

Earth is a challenging, ever-changing place, and everything from the temperature of the oceans to the amount of oxygen in the atmosphere is constantly in flux. And in this world of change, every living creature is running, swimming, slithering or flying to adapt and survive — or ends up dead.

But within this changing world, which animal has survived the longest?

In November 2010, Guinness World Records(opens in new tab) awarded the title of "oldest living creature" to Triops cancriformis, or tadpole shrimp. And for good reason: Fossils show that armored, shrimp-like crustaceans like these have been around since the Triassic period (251.9 million to 201.3 million years ago).

Tadpole shrimp have bodies like spades, which are perfect for digging at the bottom of the temporary pools they inhabit. The design works so well that they've kept it for hundreds of millions of years. But while they look the same as they always have, DNA research published since 2010 reveals that tadpole shrimp never stopped evolving underneath their armor, creating differences between species across time that human eyes can't always spot.

For instance, the tadpole shrimp T. cancriformis is merely a descendent of similar-looking Triassic ancestors and is actually no more than 25 million years old, a 2013 study published in the journal PeerJ(opens in new tab) found, and may be as young as 2.6 million years old, according to a 2012 study published in the journal PLOS One(opens in new tab).

Related: How long do new species take to evolve?

So, what about other contenders for the title of Earth's longest-surviving animal? There are several species alive today that, like tadpole shrimp, appear to have remained unchanged for many millions of years. Perhaps the most famous of these so-called "living fossils" is a group of deep-sea fish called coelacanths. Researchers first discovered coelacanth fossils in the 1800s and thought they went extinct at the end of the Cretaceous period 66 million years ago. But then, in 1938, fishers hauled up a living coelacanth off the coast of South Africa. These ancient fish date back more than 400 million years, but there's a catch.

The coelacanth species swimming in our oceans today aren't the same as the fossilized coelacanth species, which really did go extinct. A 2010 study published in the journal Marine Biology(opens in new tab) suggested the living species emerged within the last 20 million to 30 million years. The same is true for the similarly ancient horseshoe crab lineage, which stretches back around 480 million years. A 2012 study published in the journal Molecular Phylogenetics and Evolution(opens in new tab) found that the oldest living group of Asian horseshoe crabs called Tachypleus only emerged about 25 million years ago, despite looking similar to fossils that are hundreds of millions of years old.

The horseshoe crab lineage stretches back around 480 million years.

The horseshoe crab lineage stretches back around 480 million years. (Image credit: Science Photo Library via Getty Images)
Biologists haven't finished deciphering the evolutionary histories of all living animals and there won't be a definitive answer to this mystery until they do. However, tadpole shrimp, coelacanths and horseshoe crabs all tell us that even the most seemingly stable organisms are always changing.

"I don't think there is evidence that any single species has been around for more than a few million years," Africa Gómez(opens in new tab), an evolutionary biologist at the University of Hull and senior author of the 2013 tadpole shrimp study, told Live Science.

Studies of the fossil record suggest that species typically last between 500,000 years and 3 million years before they succumb to extinction or are replaced by a descendant, according to an article in the magazine American Scientist(opens in new tab).

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For instance, organisms' DNA can mutate, and these mutations can be passed on from one generation to the next. Two genetically similar species can also mate, leading to a new hybrid species that flourishes. Competition, too, forces species to evolve. Predators compete with prey, and animals sharing the same space compete for food and resources.

"Predators evolve, prey evolve, predators evolve, prey evolve, competitors evolve, other competitors evolve," Scott Lidgard(opens in new tab), emeritus curator of fossil invertebrates at the Field Museum in Chicago, told Live Science.

What's more, environmental factors can influence how long animals last. "Say a taxon [group] is well adapted to a particular kind of habitat and the climate changes dramatically, " Lidgard said. "If it can't migrate to another place with that same kind of habitat, it goes extinct."

Because change is constant, Gómez doesn't consider any animal to be a living fossil because the term gives the impression that animals stop evolving. Instead, Lidgard argued that "living fossil" can be used as an umbrella term for studying organisms with certain attributes, such as a slow rate of evolutionary change.