[This is a science video, and it mentions the role of volcanoes in creating life on Earth, and very possibly on other planets in space. Jan]
Video: Science: Weird Fact: The Universe is expanding ever faster – stars are disappearing from the sky
[This is an interesting point. This discussion by this scientist shows how very fast the universe is expanding. This takes a bit of thinking to wrap your mind around it but it seems to be quite firmly proven that the universe is expanding ever faster. Even though it is only 14 billion years old, it's width is 92 billion light years. Something like 20 stars a second are disappearing from the night sky … and these stars will NEVER be seen again … because of the expanding universe! Jan]
Photos: Scientists discover ‘living fossil’ thought to have been extinct for 273mn years on ocean floor near Japan
[A living fossil fish was discovered off the coast of South Africa in the 1930s. This is an interesting find. Jan]
Two symbiotic marine lifeforms who somehow evaded the prying eyes of human scientists and ‘disappeared’ from the fossil record over a quarter of a billion years ago have been found thriving offshore of Japan.
The creatures in question are non-skeletal corals and crinoids, or sea lilies, who were found proliferating on the floor of the Pacific Ocean, 100 meters (330 feet) below the surface, off the coasts of Honshu and Shikoku in Japan.
They managed to survive undetected, having gone AWOL from the fossil record for longer than modern humans are thought to have existed (200,000-300,000 years ago).
“These specimens represent the first detailed records and examinations of a recent syn vivo association of a crinoid (host) and a hexacoral (epibiont),” the researchers wrote.
Crinoids and corals shared a long, symbiotic relationship together millions of years ago, in which the corals would use the crinoids to climb higher off the seafloor to gain access to more food found in passing ocean currents.
The joint Polish-Japanese research team, led by paleontologist Mikolaj Zapalski of the University of Warsaw in Poland, used stereoscopic microscopy to conduct a ‘hands-off’ examination of the Paleozoic-era pals before scanning them using microtomography to gain a look at their interior structures.
They completed their non-invasive investigation using DNA barcoding to identify the exact species.
The researchers found that these newly rediscovered specimens did not modify the structure of the crinoids’ skeletons, providing a possible clue as to why they disappeared from the fossil record for so long; fossils of soft-bodied organisms are vanishingly rare.
Science & Evolution: Hybrid Animals Are Not Nature’s Misfits
In the 20th century, animals such as mules and ligers that had parents of different species were considered biological flukes, but genetic sequencing is beginning to unravel the critical role of hybridization in evolution.
Ashley Yeager
May 1, 2021
This liger cub and other hybrid animals were thought to be biological rarities, but recent studies have revealed cross-species animals are more common than once thought.
ABOVE: FROM © ISTOCK.COM, W1ZZARD
The whale’s teeth were what had caught molecular ecologist Eline Lorenzen’s attention. Of the 18 chompers lining the front of the skull’s mouth, some were twisted, not unlike a narwhal’s tusk. But the 30-year-old specimen, hidden away in the basement of the Natural History Museum of Denmark at the University of Copenhagen, didn’t have a tusk at all. When Lorenzen became director of the museum in 2015, she decided to examine the skull more closely. Working with a team of collaborators, she extracted genetic material and compared it with DNA from the teeth of narwhal and beluga specimens in the museum. The skull, it turned out, was the first-ever confirmed narluga, the son of a beluga dad and a narwhal mom.
A deeper dive into the history of the skull (it had been found fixed atop a hunter’s home) revealed that this animal may not have been the only one of its kind. The hunter said he’d seen it with two other similar-looking whale creatures, and he, apparently, isn’t the only one to have seen a narluga. In fact, they are common enough that natives of western Greenland have a word for the narwhal-beluga hybrid, itorsaq.
Because several narlugas have been spotted before, researchers suspect that the creatures may be fertile, and that some narlugas may be the product of two narluga parents rather than one beluga and one narwhal. That notion challenges naturalists’ traditional view of hybrids as the result of maladaptive crossings, such as when a female horse mates with a male donkey and gives birth to a sterile mule. If the hybrids can’t reproduce, they would seem to be irrelevant evolutionarily, but studies of the narluga and other naturally occurring hybrids have begun to hint that such offspring may not be the biological misfits they were once thought to be. They are not evolutionary dead-ends, and in some cases, may serve as evolutionary accelerators.
“We’re beginning to realize that hybridization exists in the evolutionary history of many organisms we didn’t expect it to, including Homo sapiens,” Scott Taylor, an evolutionary ecologist at the University of Colorado Boulder, tells The Scientist.
Snowshoe Hares Borrow from Black-Tailed Jackrabbits
At some point in the past, black-tailed jackrabbits (Lepus californicus) and snowshoe hares (L. americanus) crossbred, with the hybrids mating again with snowshoe hares. A combination of whole-genome and whole-exome sequencing revealed that the resultant hares retained a variation of the Agouti gene that led to brown, rather than white, coat color in hare populations experiencing mild, less snowy winters, allowing them to better blend into the drab surroundings of dirt and dead leaves. See full infographic: WEB |
Hybridization’s benefits are not a new idea
As far back as the 1930s, botanists realized that hybridization plays a role in the evolution of plant species. In 1938, Edgar Anderson and Leslie Hubricht laid out the idea of introgression to describe the hybridization of species of herbaceous perennial wildflowers of the Tradescantia genus. The crosses led to offspring with an even split of parental genetic material, and typically those offspring then repeatedly bred with one of the original parent species, while still retaining genetic material from the other parent species. Alternatively, hybrids bred with other hybrids, and, eventually, entirely new plant species would emerge.
Zoologists knew about these and other examples of hybridization in the plant world, but there was a perception, Taylor says, that cross-species breeding was much less common in animals. That idea stemmed from biologist Ernst Mayr’s description in the 1940s of the biological characteristics that defined species—essentially, any animal population that could not or did not breed with other, similar populations. For more than two decades, including in his 1963 book Animal Species and Evolution, Mayr argued that “the evolutionary importance of hybridization seems small in the better-known groups of animals.” But the idea is not universally accepted, Taylor says. “I don’t know a lot of evolutionary biologists who study hybridization who adhere strictly to that concept.”
Despite the dogma that hybrid animals in nature were rare and therefore not catalysts of evolutionary innovation, some biologists continued to study them, curious to uncover the barriers that prevented them from becoming new species, identify the new gene combinations created by hybridization, and understand how natural selection acted upon them. Focusing on animals in what scientists call hybrid zones—geographical regions in which two species interbreed to produce offspring of mixed ancestry—researchers in the late 1980s and early 1990s began to show that, contrary to the prevailing viewpoint, hybridization was a valid mechanism of evolutionary change—one that could radically influence an animal’s ability to adapt to its environment.
A Narwhal Tries Beluga’s Teeth
A genetic analysis of a rare skull found at the Natural History Museum of Denmark showed that in the past few decades a male beluga (Delphinapterus leucas) and a female narwhal (Monodon monoceros) mated, creating a hybrid called a narluga that looked a bit like both. The animal’s 18 teeth were small, like a beluga’s, and twisted, like a narwhal’s tusk. Those teeth may have changed the way the narluga fed, not hunting on cod, squid, and shrimp in the water column as both of its parents did, but instead feeding off the bottom. Its teeth may have allowed it and others like it to occupy a different ecological niche than its parents. See full infographic: WEB |
The thousands of cichlids in Africa’s lakes
Evidence for hybrid-driven adaptation is perhaps nowhere more profound than in the warm, tropical waters of Lake Victoria in Africa. There, more than 500 species of bony fishes called cichlids that sport brilliant orange, yellow, and blue hues, roam the lake’s 2,400 cubic kilometers. Some species eat only plants, others eat invertebrates, the bigger species eat other fish, and still more feed on Lake Victoria’s detritus. “There’s incredible diversity of species that live together in the same ecosystem,” evolutionary ecologist Ole Seehausen of the University of Bern tells The Scientist. “This struck me as a beautiful system, the interaction between ecology and evolution . . . to study speciation.”
When Seehausen began to study the lake’s cichlids roughly 30 years ago, it wasn’t clear how the hundreds of species there had evolved. They weren’t geographically isolated, a common driver of speciation. Rather, the fish were all living in the same lake and could interact, yet there was still incredible cichlid diversity. Something else appeared to be driving their speciation.
With continued observation, Seehausen and others found that the barriers preventing the species in the lakes from mating were rather “shallow,” with some of the major ones being behavioral in nature. Males, for example, were defending their territories from males of both the same and other species, or females were choosing flashing mates of only their own species. That last barrier, based on color signaling, began to break down, Seehausen says, when the clarity of the water diminished in the 1990s, a result of wastewater from farms and other human activities polluting the lake. “It turns out that when you change the visual signaling, and the perception of those signals, then not much more is needed to break down reproductive isolation, so many species then hybridize,” Seehausen says.
Something similar appears to have happened thousands of years ago in Lake Victoria. Genetic analyses of the cichlids have revealed that their vast diversity can be traced back to a hybridization of two divergent lineages around 150,000 years ago. And Lake Victoria wasn’t the only body of water in the region where hybridization appeared to play an important role in speciation. Further investigation revealed that cross-species mating had happened and continued to occur in nearby lakes, where it was driving cichlid diversity. “This was replicated in several different lakes across Africa,” Seehausen says.
As scientists began to look for other examples of hybridization in the wild, both past and present, they were not disappointed. Genetic analyses have revealed crosses between coyotes and gray wolves, polar bears and brown bears, chimpanzees and bonobos, finches in the Galapagos Islands, fish called sculpin, and even modern humans and Neanderthals.
See “Neanderthal DNA in Modern Human Genomes Is Not Silent”
Researchers suspect that hybridization events are perhaps becoming more common, as human disturbances shift species ranges in ways that promote breeding across similar species. In Colorado, for example, two varieties of small, nonmigratory birds—black-capped chickadees and mountain chickadees—have recently hybridized in areas being heavily developed by humans. “If you look at the map and squint, the places they’re hybridizing seems to correlate nicely with places that humans have modified, whether that’s the front range of the Rocky Mountains or Albuquerque, New Mexico,” he says. His team hypothesizes that the species, which split some 1.5 million years ago, breed with each other in modified habitats because a resource needed by both, either breeding grounds or certain food sources, is bringing the birds together.
On occasion, a mountain chickadee (above) may mate with a black-capped chickadee.
ROBERT TAYLOR
Climate change may also be driving hybridization between species. Evolutionary biologists have seen pulses of cross-breeding as species shift where they live to higher or lower latitudes or altitudes to find cooler temperatures. When they move into those regions, the barriers to hybridization, such as differences in mate choice or other factors, might disappear. “There are definitely compelling examples” of climate change or environmental shifts influencing hybridization, says Molly Schumer, an evolutionary biologist at Stanford University, “and my suspicion is it’s pretty widespread.”
Obviously not all cases of hybridization involved the equal swapping of genes to form a completely new creature, as appeared to often happen with the cichlids, but in just the last few years, “the consensus has been that hybridization in animals in particular is hugely widespread and much more common than was appreciated,” Schumer says. The question in the field now, she says, is if this gene swapping is common, “what is it doing?”
Fish in Troubled Waters
When the waters in Lake Victoria in Africa became increasingly murky in the 1990s after mineral and farm runoff levels increased, two species of cichlids (Haplochromis nyererei and Neochromis sp. Bihiru scraper) no longer selectively mated with conspecifics, whom they had previously identified based on color. They hybridized readily, and others in the lake did too, creating new species, some of which have pervaded the altered ecological niches and adapted to them better than their parent species have. See full infographic: WEB |
Cross-breeding’s advantages and disadvantages
In the case of cichlid hybrids, Seehausen found that not only did the hybrids have similar developmental and reproductive rates to non-hybrids, in some ways individuals with a genetic mishmash of two distinct species created were actually more suited to a particular environment or food source than their parents were.
A few years ago, Joana Meier, an evolutionary genomicist at the University of Cambridge who did her graduate work and a postdoctoral stint with Seehausen, delved into the genetics of the cichlids and spotted one type of hybrid that caught her attention: dwarf species that combine the body shape of a plant-eating species with the predatory habits of a bigger species that dines on other fish. “Genetically, they’re like a mix of both,” she says. “In some cases, they have higher fitness [than either parent species] in different ecological niches.” Seehausen has also shown this in the lab, creating hybrids that don’t thrive on the food the parent species ate, but gobble down a new type of food and begin to flourish.
Schumer is seeing something similar in the hybridization of two related species of swordtail fish, Xiphophorus malinche and X. birchmanni. The fish live in the rivers of the Mexican state of Hidalgo and have begun hybridizing within the last 50 to 100 generations, probably as a result of some human disturbance to the river, she explains. The fish rely on their sense of smell and the signals in those scents to choose mates, but the contaminants in the rivers appear to be blocking the fish from picking out their own species, Schumer says, so they’ve ended up mating across species boundaries. It turns out, that the mix-up could be helping both species survive by boosting genetic diversity.
Different species of swordtail fish, including Xiphophorus birchmanni (left) and X. malinche (top), can interbreed to form hybrid offspring (bottom).
DAN POWELL
Swordtail cross-breeding is “really, really recent and gives us a good snapshot to [see] what’s happening right after hybridization,” Schumer says. Her genetic studies, along with those from other researchers investigating recent hybridization events, seem to show that right after these crosses occur, the genome of the hybrid undergoes incredible reorganization. “There’s a lot of purging of deleterious alleles and rapid evolution happening right after you collide these two divergent genomes.” The original swordtail parent species are closely related, differing by only 0.5 percent in their genetic makeup, Schumer’s studies show. Still, that small bit of genetic variation leads to substantial shifts in the species’ tolerances to cold, adaptation to elevation, and even an extra-long fin extension, called the sword, seen on X. birchmanni but not on X. malinche.
On the flip side, mushing together the two swordtail species’ genomes can cause issues in the offspring, with many not being able to reproduce. The combination of genes can even cause the hybrids to develop tumorous melanoma, which the parents don’t. “One of the biggest questions in the field,” Schumer says, “is: In this really rapid genome evolution happening after hybridization, how are all of these mechanisms—positive effects of hybridization, negative effects of hybridization, interactions with the environment, social interactions—playing out?”
Video: Africa: A New Ocean Is Forming Under Your Feet Right Now
[Some interesting science. Jan]
Scientific Fact & Maths: How to Predict Everything
[This is actually very quaint. I spotted this while investigating this scientist. I think one can perhaps refine it a bit into something almost usable. For example, according to this method, due to me being in my late 50's, I can use this method to predict how long I will live. Thus I can say with 95% scientific certainty that I will live another at least 1.4 years or as long as 3,000 years of age!!! 🙂 So this system needs a bit of refining, but I like the mathematical basis. Jan]
The New Yorker, July 12, 1999 P. 35
ANNALS OF SCIENCE about the prediction theory put forward by Princeton astrophysicist J. Richard Gott III, 52… In the seventies, he and several colleagues published an influential paper arguing that the universe is geometrically “open”–meaning that it will go on expanding forever. Then, building on research pioneered by Kip Thorne, the eminent black-hole theorist at Caltech, he identified circumstances under which time travel into the past might be possible, inside black holes. This work has held up well, and has contributed to Gott’s growing reputation as a provocateur whose ideas, although sometimes startling, are difficult to dismiss… Gott is exquisitely serious about science, and is given to long-playing discourses—he can spend forty minutes answering a question without wasting a word—but a playful irony is seldom far from the thread of his conversation…. The question that Gott has been asking lately is how long the human species is going to last. Since scientists generally make predictions at the ninety-five-per-cent confidence level, Gott begins with the assumption that you and I, having no reason to think we’ve been born in a special time, are probably living during the middle ninety-five per cent of the ultimate duration of our species. In other words, we’re probably living neither during the first two and a half per cent nor during the last two and a half per cent of all the time that human beings will have existed. “Homo sapiens has been around for two hundred thousand years,” Gott said, once we’d finished our entrees. “That’s how long our past is. Two and a half per cent is equal to one-fortieth, so the future is probably at least one-thirty-ninth as long as the past but not more than thirty-nine times the past. If we divide two hundred thousand years by thirty-nine, we get about fifty-one hundred years. If we multiply it by thirty-nine, we get 7.8 million years. So if our location in human history is not special, there’s a ninety-five-per-cent chance we’re in the middle ninety-five per cent of it. Therefore the human future is probably going to last longer than fifty-one hundred years but less than 7.8 million years. “Now, those numbers are interesting, because they give us a total longevity that’s comparable to that of other species. The predicted total lifetime of the human species is quite similar to the ranges we see for other species—species that have gone extinct. Homo erectus, our ancestor species, lasted for about 1.6 million years. The Neanderthals went extinct after about three hundred thousand years. The mean duration for all mammal species is two million years.”… Gott, after rummaging around in his attache case, produced a set of dominoes, which he set up in five stacks of doubling height, starting with one domino and ending with a stack of sixteen. “These dominoes represent the human population over time,” he said. “We’ve gone through a period of exponential growth, so I have one, two, four, eight, and then sixteen dominoes. Now, what’s going to happen in the future? One prospect is that the population will reach a peak, then go back down at a similar rate. This is something that has happened to many species: you have an exponential growth rate that reaches a peak and then something bad happens and you have an exponential decline. In that case, you would expect to be right about here, near the peak. Most people are. And that’s where we are… If the population is going to decline, then we’re living in exactly a typical place, just as one would expect.” …This is the part of Gott’s argument that most troubles me—not because I can find fault with it but because I can’t. It ranks as one of the most baleful prognostications of the human fate since Malthus. Gott went happily on, tapping his right index finger on the domino plateau. “A lot of people say, ‘Well, our species may go out of existence, but we’ll be replaced by smarter, genetically engineered human beings. We’ll have many descendant species, so we shouldn’t mourn if Homo sapiens goes extinct, because we’ll be replaced by something much better.’ But, as Mr. Darwin noted, most species do not leave any descendants. A few do, and they leave a lot: there are sixteen species of rodents. Our genus, Homo, is down to one. We’re like the horse. There used to be several, now there’s only one. There used to be several different hominid species—the Neanderthals and us, for example—and now we’re down to one.” This is not a good sign. Describes his argument for colonizing Mars… “The manned space program is thirty-eight years old, so it’s been around only a short time,” he said. “Things that haven’t been around a very long time are not likely to be around very long in the future. So there’s a real danger that we will quit it, as the Chinese did in the fifteenth century. They explored Africa, came back with a giraffe that everybody wondered at, and then they just quit. The period of great Egyptian pyramid-building lasted about a century from the first to the biggest; then there was a long, slow decline during which the Egyptians built crummy ones. So there’s a danger that we’ll end up stuck on the earth—that if we wait too long we may have a population that’s too small to respond to an emergency or to do space colonization.”… Outside, at the curb, I waved goodbye as Gott’s car headed crosstown, bound for Princeton. That car is about a year old, I thought, so it’s likely to keep running for more than a week but less than thirty-nine more years. New York City was first settled in 1626; that gives it nine and a half to 14,500 years to go. Jupiter stood high in the southern sky, warranteed for at least another hundred and fourteen million years. Science, like art, changes the way one looks at things.
Source: https://www.newyorker.com/magazine/1999/07/12/how-to-predict-everything
Video: Mars: First ever flight of an aircraft on another planet! – Watch the Ingenuity helicopter’s first flight on Mars
[This is amazing. Yet another Western science first. I was keen to see this, and they managed to film it. It's incredible. They've done 2 flights on Mars. They have 4 planned in total before the vehicle is destroyed by the cold. Each flight will be more ambitious and longer and more complex. This is going to be astounding. The atmosphere is 1% that of the Earth's so making the helicopter fly is really tricky and the rotor blades have to spin extremely fast. It will be very awesome when vehicles on other planets can begin flying around the planets! Jan]
Humans just made history: flying an autonomous helicopter on another planet, more than 100 million miles away.
Here’s the video: https://www.youtube.com/watch?v=0gQDnzpy1n4
Video: Science: Gravitas: Weird: Scientists detect X-rays from Uranus
[I've never heard of anything like this before. I have never yet heard of X-rays emanating from the centre of a planet. Jan]
For the first time ever, Astronomers have detected X-rays from Uranus. It’s unusual but is it good news or bad news?
Video: 430,000 Years ago: Signs of a Huge Asteroid Explosion in Antarctica Long Ago
An asteroid seems to have exploded over Antarctica with a tremendous power.
Science: Is there an ancient black hole at the edge of the solar system?
Hints of a hefty source of gravity beyond Pluto sparked the search for a possible “Planet Nine”. Now, some astronomers think it could instead be a black hole from the big bang, offering a rare glimpse into the early universe
SPACE 31 March 2021
By Stuart Clark
BEYOND the giant planets of the outer solar system lies a vast wilderness. Most astronomers think it is inhabited by a population of small, icy worlds similar to Pluto, and several groups have dedicated themselves to tracking down these dwarf planets. In the process, some have come to suspect that something bigger is lurking out there: a planet several times the mass of Earth.
They believe that this hypothetical world, known as Planet Nine, betrays its presence by the way its gravity has aligned the orbits of a group of these small, icy bodies. The problem is that no one can imagine how a planet big enough to do that could form so far from the sun. “All we know is that there’s an object of a certain mass out there,” says Jakub Scholtz, a theorist at Durham University in the UK. “The observations we have can’t tell us what that object is.”
But if not a planet, then what? Scholtz suspects it could be something even more exotic: a primordial black hole, one forged in the big bang.
If he is right, it would be a stunning discovery. Primordial black holes would give us a new window onto the early universe. They might even comprise dark matter, the mysterious substance that holds galaxies together. All of which explains why cosmologists have been scouring the universe for them. But no one had dared to dream we might find one in our own backyard.
The question now is, how can we determine what the mysterious source of gravity lurking at the fringes of our solar system really is? …