The discovery of the Kuiper Belt revamped our view of the solar system

On a Hawaiian mountaintop in the summer of 1992, a pair of scientists spotted a pinprick of light inching through the constellation Pisces. That unassuming object — located over a billion kilometers beyond Neptune — would rewrite our understanding of the solar system.

Rather than an expanse of emptiness, there was something, a vast collection of things in fact, lurking beyond the orbits of the known planets.

The scientists had discovered the Kuiper Belt, a doughnut-shaped swath of frozen objects left over from the formation of the solar system.

As researchers learn more about the Kuiper Belt, the origin and evolution of our solar system is coming into clearer focus. Closeup glimpses of the Kuiper Belt’s frozen worlds have shed light on how planets, including our own, might have formed in the first place. And surveys of this region, which have collectively revealed thousands of such bodies, called Kuiper Belt objects, suggest that the early solar system was home to pinballing planets.

The humble object that kick-started it all is a chunk of ice and rock roughly 250 kilometers in diameter. It was first spotted 30 years ago this month.
Staring into space
In the late 1980s, planetary scientist David Jewitt and astronomer Jane Luu, both at MIT at the time, were several years into a curious quest. The duo had been using telescopes in Arizona to take images of patches of the night sky with no particular target in mind. “We were literally just staring off into space looking for something,” says Jewitt, now at UCLA.

An apparent mystery motivated the researchers: The inner solar system is relatively crowded with rocky planets, asteroids and comets, but there was seemingly not much out beyond the gas giant planets, besides small, icy Pluto. “Maybe there were things in the outer solar system,” says Luu, who now works at the University of Oslo and Boston University. “It seemed like a worthwhile thing to check out.”
Poring over glass photographic plates and digital images of the night sky, Jewitt and Luu looked for objects that moved extremely slowly, a telltale sign of their great distance from Earth. But the pair kept coming up empty. “Years went by, and we didn’t see anything,” Luu says. “There was no guarantee this was going to work out.”

The tide changed in 1992. On the night of August 30, Jewitt and Luu were using a University of Hawaii telescope on the Big Island. They were employing their usual technique for searching for distant objects: Take an image of the night sky, wait an hour or so, take another image of the same patch of sky, and repeat. An object in the outer reaches of the solar system would shift position ever so slightly from one image to the next, primarily because of the movement of Earth in its orbit. “If it’s a real object, it would move systematically at some predicted rate,” Luu says.

By 9:14 p.m. that evening, Jewitt and Luu had collected two images of the same bit of the constellation Pisces. The researchers displayed the images on the bulbous cathode-ray tube monitor of their computer, one after the other, and looked for anything that had moved. One object immediately stood out: A speck of light had shifted just a touch to the west.

But it was too early to celebrate. Spurious signals from high-energy particles zipping through space — cosmic rays — appear in images of the night sky all of the time. The real test would be whether this speck showed up in more than two images, the researchers knew.

Jewitt and Luu nervously waited until 11 p.m. for the telescope’s camera to finish taking a third image. The same object was there, and it had moved a bit farther west. A fourth image, collected just after midnight, revealed the object had shifted position yet again. This is something real, Jewitt remembers thinking. “We were just blown away.”
Based on the object’s brightness and its leisurely pace — it would take nearly a month for it to march across the width of the full moon as seen from Earth — Jewitt and Luu did some quick calculations. This thing, whatever it was, was probably about 250 kilometers in diameter. That’s sizable, about one-tenth the width of Pluto. It was orbiting far beyond Neptune. And in all likelihood, it wasn’t alone.

Although Jewitt and Luu had been diligently combing the night sky for years, they had observed only a tiny fraction of it. There were possibly thousands more objects out there like this one just waiting to be found, the two concluded.

The realization that the outer solar system was probably teeming with undiscovered bodies was mind-blowing, Jewitt says. “We expanded the known volume of the solar system enormously.” The object that Jewitt and Luu had found, 1992 QB1 (SN: 9/26/92, p. 196), introduced a whole new realm.

Just a few months later, Jewitt and Luu spotted a second object also orbiting far beyond Neptune (SN: 4/10/93, p. 231). The floodgates opened soon after. “We found 40 or 50 in the next few years,” Jewitt says. As the digital detectors that astronomers used to capture images grew in size and sensitivity, researchers began uncovering droves of additional objects. “So many interesting worlds with interesting stories,” says Mike Brown, an astronomer at Caltech who studies Kuiper Belt objects.

Finding all of these frozen worlds, some orbiting even beyond Pluto, made sense in some ways, Jewitt and Luu realized. Pluto had always been an oddball; it’s a cosmic runt (smaller than Earth’s moon) and looks nothing like its gas giant neighbors. What’s more, its orbit takes it sweeping far above and below the orbits of the other planets. Maybe Pluto belonged not to the world of the planets but to the realm of whatever lay beyond, Jewitt and Luu hypothesized. “We suddenly understood why Pluto was such a weird planet,” Jewitt says. “It’s just one object, maybe the biggest, in a set of bodies that we just stumbled across.” Pluto probably wouldn’t be a member of the planet club much longer, the two predicted. Indeed, by 2006, it was out (SN: 9/2/06, p. 149).

Up-close look
The discovery of 1992 QB1 opened the world’s eyes to the Kuiper Belt, named after Dutch-American astronomer Gerard Kuiper. In a twist of history, however, Kuiper predicted that this region of space would be empty. In the 1950s, he proposed that any occupants that might have once existed there would have been banished by gravity to even more distant reaches of the solar system.

In other words, Kuiper anti-predicted the existence of the Kuiper Belt. He turned out to be wrong.

Today, researchers know that the Kuiper Belt stretches from a distance of roughly 30 astronomical units from the sun — around the orbit of Neptune — to roughly 55 astronomical units. It resembles a puffed-up disk, Jewitt says. “Superficially, it looks like a fat doughnut.”

The frozen bodies that populate the Kuiper Belt are the remnants of the swirling maelstrom of gas and dust that birthed the sun and the planets. There’s “a bunch of stuff that’s left over that didn’t quite get built up into planets,” says astronomer Meredith MacGregor of the University of Colorado Boulder. When one of those cosmic leftovers gets kicked into the inner solar system by a gravitational shove from a planet like Neptune and approaches the sun, it turns into an object we recognize as a comet (SN: 9/12/20, p. 14). Comets that circle the sun once only every 200 years or more typically derive from the solar system’s even more distant repository of icy bodies known as the Oort cloud.
In scientific parlance, the Kuiper Belt is a debris disk (SN Online: 7/28/21). Distant solar systems contain debris disks, too, scientists have discovered. “They’re absolutely directly analogous to our Kuiper Belt,” MacGregor says.

In 2015, scientists got their first close look at a Kuiper Belt object when NASA’s New Horizons spacecraft flew by Pluto (SN Online: 7/15/15). The pictures that New Horizons returned in the following years were thousands of times more detailed than previous observations of Pluto and its moons. No longer just a few fuzzy pixels, the worlds were revealed as rich landscapes of ice-spewing volcanoes and deep, jagged canyons (SN: 6/22/19, p. 12; SN Online: 7/13/18). “I’m just absolutely ecstatic with what we accomplished at Pluto,” says Marc Buie, an astronomer at the Southwest Research Institute in Boulder, Colo., and a member of the New Horizons team. “It could not possibly have gone any better.”

But New Horizons wasn’t finished with the Kuiper Belt. On New Year’s Day of 2019, when the spacecraft was almost 1.5 billion kilometers beyond Pluto’s orbit, it flew past another Kuiper Belt object. And what a surprise it was. Arrokoth — its name refers to “sky” in the Powhatan/Algonquian language — looks like a pair of pancakes joined at the hip (SN: 12/21/19 & 1/4/20, p. 5; SN: 3/16/19, p. 15). Roughly 35 kilometers long from end to end, it was probably once two separate bodies that gently collided and stuck. Arrokoth’s bizarre structure sheds light on a fundamental question in astronomy: How do gas and dust clump together and grow into larger bodies?

One long-standing theory, called planetesimal accretion, says that a series of collisions is responsible. Tiny bits of material collide and stick together on repeat to build up larger and larger objects, says JJ Kavelaars, an astronomer at the University of Victoria and the National Research Council of Canada. But there’s a problem, Kavelaars says.
As objects get large enough to exert a significant gravitational pull, they accelerate as they approach one another. “They hit each other too fast, and they don’t stick together,” he says. It would be unusual for a large object like Arrokoth, particularly with its two-lobed structure, to have formed from a sequence of collisions.

More likely, Arrokoth was born from a process known as gravitational instability, researchers now believe. In that scenario, a clump of material that happens to be denser than its surroundings grows by pulling in gas and dust. This process can form planets on timescales of thousands of years, rather than the millions of years required for planetesimal accretion. “The timescale for planet formation completely changes,” Kavelaars says.

If Arrokoth formed this way, other bodies in the solar system probably did too. That may mean that parts of the solar system formed much more rapidly than previously believed, says Buie, who discovered Arrokoth in 2014. “Already Arrokoth has rewritten the textbooks on how solar system formation works.”

What they’ve seen so far makes scientists even more eager to study another Kuiper Belt object up close. New Horizons is still making its way through the Kuiper Belt, but time is running out to identify a new object and orchestrate a rendezvous. The spacecraft, which is currently 53 astronomical units from the sun, is approaching the Kuiper Belt’s outer edge. Several teams of astronomers are using telescopes around the world to search for new Kuiper Belt objects that would make a close pass to New Horizons. “We are definitely looking,” Buie says. “We would like nothing better than to fly by another object.”

All eyes on the Kuiper Belt
Astronomers are also getting a wide-angle view of the Kuiper Belt by surveying it with some of Earth’s largest telescopes. At the Canada-France-Hawaii Telescope on Mauna Kea — the same mountaintop where Jewitt and Luu spotted 1992 QB1 — astronomers recently wrapped up the Outer Solar System Origins Survey. It recorded more than 800 previously unknown Kuiper Belt objects, bringing the total number known to roughly 3,000.
This cataloging work is revealing tantalizing patterns in how these bodies move around the sun, MacGregor says. Rather than being uniformly distributed, the orbits of Kuiper Belt objects tend to be clustered in space. That’s a telltale sign that these bodies got a gravitational shove in the past, she says.

The cosmic bullies that did that shoving, most astronomers believe, were none other than the solar system’s gas giants. In the mid-2000s, scientists first proposed that planets like Neptune and Saturn probably pinballed toward and away from the sun early in the solar system’s history (SN: 5/5/12, p. 24). That movement explains the strikingly similar orbits of many Kuiper Belt objects, MacGregor says. “The giant planets stirred up all of the stuff in the outer part of the solar system.”

Refining the solar system’s early history requires observations of even more Kuiper Belt objects, says Meg Schwamb, an astronomer at Queen’s University Belfast in Northern Ireland. Researchers expect that a new astronomical survey, slated to begin next year, will find roughly 40,000 more Kuiper Belt objects. The Vera C. Rubin Observatory, being built in north-central Chile, will use its 3,200-megapixel camera to repeatedly photograph the entire Southern Hemisphere sky every few nights for 10 years. That undertaking, the Legacy Survey of Space and Time, or LSST, will revolutionize our understanding of how the early solar system evolved, says Schwamb, a cochair of the LSST Solar System Science Collaboration.
It’s exciting to think about what we might learn next from the Kuiper Belt, Jewitt says. The discoveries that lay ahead will be possible, in large part, because of advances in technology, he says. “One picture with one of the modern survey cameras is roughly a thousand pictures with our setup back in 1992.”

But even as we uncover more about this distant realm of the solar system, a bit of awe should always remain, Jewitt says. “It’s the largest piece of the solar system that we’ve yet observed.”

News stories have caught spiders in a web of misinformation

Even spiders, it seems, have fallen victim to misinformation.

Media reports about people’s encounters with spiders tend to be full of falsehoods with a distinctly negative spin. An analysis of a decade’s worth of newspaper stories from dozens of countries finds that nearly half of the reports contain errors, arachnologist Catherine Scott and colleagues report August 22 in Current Biology.

“The vast majority of the spider content out there is about them being scary and hurting people,” says Scott, of McGill University in Montreal. In reality, they note, “spiders almost never bite people.”
Of the roughly 50,000 known spider species, vanishingly few are dangerous. Instead, many spiders benefit us by eating insects like mosquitoes that are harmful to people. Even with the rare exceptions like brown recluse and black widow spiders, bites are extremely uncommon, Scott says. Some stories about bites blamed spiders that don’t occur in the area, and others reported symptoms that don’t match symptoms of actual bites. “So many stories about spider bites included no evidence whatsoever that there was any spider involved,” they say.

To conduct the study, Scott and their colleagues analyzed over 5,000 online newspaper stories about humans and spiders from 2010 to 2020 across 81 countries. In addition to errors, the team determined that 43 percent of the stories were sensationalized, often using words like nasty, killer, agony and nightmare. International and national newspapers were more likely to sensationalize spiders than regional outlets. Stories that included a spider expert were less sensationalistic, though there was no such effect from other experts, including doctors.

If people knew the truth about spiders, they could spend less time blaming them for bites and killing them with pesticides that are toxic to many other species, including humans, Scott says. Clearing up the misinformation would be good for spiders, too — especially the one in your house that doesn’t get squashed out of fear. Spiders in general stand to benefit, the researchers conclude, because news helps shape public opinion, which can influence decisions about wildlife conservation.

“Spiders are kind of unique in that they seem to be really good at capturing people’s attention,” says arachnologist Lisa Taylor at the University of Florida in Gainesville, who was not involved in the study. “If that attention is paired with real information about how fascinating they are, rather than sensationalistic misinformation, then I think spiders are well-suited to serve as tiny ambassadors for wildlife in general.”

Not one, but two asteroids might have slain the dinosaurs

Chicxulub, the asteroid that wiped out most dinosaurs, might have had a little sibling.

Off the coast of West Africa, hundreds of meters beneath the seafloor, scientists have identified what appears to be the remains of an 8.5-kilometer-wide impact crater, which they’ve named Nadir. The team estimates that the crater formed roughly around the same time that another asteroid — Chicxulub, the dinosaur killer — slammed into modern day Mexico (SN: 1/25/17). If confirmed, it could mean that nonbird dinosaurs met their demise by a one-two punch of asteroids, researchers report in the Aug. 17 Science Advances.
“The idea that [Chicxulub] had help — for want of a better phrase — would have really added insult to serious injury,” says study coauthor Veronica Bray, a planetary scientist at the University of Arizona in Tucson.

Nearly 200 impact craters have been discovered on Earth (SN: 12/18/18), the vast majority of which are on land. That’s because impact craters at sea gradually become buried under sediment, Bray says, which makes the Nadir structure a valuable scientific find, regardless of its birthdate.

Geologist Uisdean Nicholson of Heriot-Watt University in Edinburgh happened upon the structure while analyzing data collected by seismic waves transmitted underground to detect physical structures offshore of Guinea. Lurking beneath the seafloor — and under nearly 1 kilometer of water — he discerned a bowl-shaped structure with a broken-up, terraced floor and a pronounced central peak — features expected of a large impact.

Based on the structure’s dimensions, Bray, Nicholson and their colleagues calculate that, if an asteroid was responsible for the terrain, it would probably have been over 400 meters wide. What’s more, the researchers estimate that the impact would have rocked the ground like a magnitude 7 earthquake and stirred tsunamis hundreds of meters high.

Despite that fallout, the Nadir impact would have been far less devastating than the one from the roughly 10-kilometer-wide Chicxulub asteroid, says Michael Rampino, a geologist from New York University who was not involved in the study. “It certainly wouldn’t have had global effects,” he says.

Using geologic layers adjacent to Nadir, some with ages obtained by past studies, the team estimated the structure to have formed around the end of the Cretaceous period — 66 million years ago. The Nadir asteroid may even have formed a pair with the Chicxulub asteroid, the two having been ripped apart by gravitational forces during a previous Earth flyby, the researchers speculate.
But the study’s conclusions have some experts wary. “It looks like an impact crater, but it could also be something else,” says geologist Philippe Claeys of Vrije Universiteit Brussel in Belgium, who was not involved in the research. Confirming that the structure is an impact crater will require drilling for solid evidence, such as shocked quartz, he says. Alternative explanations for the structure’s identity include a collapsed volcanic caldera or a squeezed body of salt called a salt diapir.

The Nadir structure’s age is another uncertainty. The seismic data shows it appears to have formed sometime near the end the Cretaceous period or maybe a little later, Claeys says. “But that’s around the best they can say.” Drilling in the crater for minerals that contain radioactive elements could provide a more precise date of formation, Rampino says.

It’s not the first time that scientists have investigated whether Chicxulub had an accomplice. Some studies have suggested that the Boltysh crater in Ukraine may have formed at the same time as Chicxulub, though researchers have since determined that Boltysh formed 650,000 years later.

Bray and her colleagues are currently negotiating for funding to collect samples from the crater, with aspirations to drill in 2024. That will hopefully settle some of the debate surrounding Nadir’s origins, Bray says, though new questions will probably arise too. “If we do prove that this is the sister of the dinosaur killer, then how many other siblings are there?”

Sea urchin skeletons’ splendid patterns may strengthen their structure

Sea urchin skeletons may owe some of their strength to a common geometric design.

Components of the skeletons of common sea urchins (Paracentrotus lividus) follow a similar pattern to that found in honeycombs and dragonfly wings, researchers report in the August Journal of the Royal Society Interface. Studying this recurring natural order could inspire the creation of strong yet lightweight new materials.

Urchin skeletons display “an incredible diversity of structures at the microscale, varying from fully ordered to entirely chaotic,” says marine biologist and biomimetic consultant Valentina Perricone. These structures may help the animals maintain their shape when faced with predator attacks and environmental stresses.

While using a scanning electron microscope to study urchin skeleton tubercules — sites where the spines attach that withstand strong mechanical forces — Perricone spotted “a curious regularity.” Tubercules seem to follow a type of common natural order called a Voronoi pattern, she and her colleagues found.
Using math, a Voronoi pattern is created by a process that divides a region into polygon-shaped cells that are built around points within them called seeds (SN: 9/23/18). The cells follow the nearest neighbor rule: Every spot inside a cell is nearer to that cell’s seed than to any other seed. Also, the boundary that separates two cells is equidistant from both their seeds.

A computer-generated Voronoi pattern had an 82 percent match with the pattern found in sea urchin skeletons. This arrangement, the team suspects, yields a strong yet lightweight skeletal structure. The pattern “can be interpreted as an evolutionary solution” that “optimizes the skeleton,” says Perricone, of the University of Campania “Luigi Vanvitelli” in Aversa, Italy.

Urchins, dragonflies and bees aren’t the only beneficiaries of Voronoi architecture. “We are developing a library of bioinspired, Voronoi-based structures” that could “serve as lightweight and resistant solutions” for materials design, Perricone says. These, she hopes, could inspire new developments in materials science, aerospace, architecture and construction.

A new James Webb telescope image reveals a galactic collision’s aftermath

It’s not easy being ringed. A newly released image from the James Webb Space Telescope, or JWST, shows the Cartwheel Galaxy still reeling from a run-in with a smaller galaxy 400 million years ago.

The Cartwheel Galaxy, so called because of its bright inner ring and colorful outer ring, lies about 500 million light-years from Earth. Astronomers think it used to be a large spiral like the Milky Way, until a smaller galaxy smashed through it. In earlier observations with other telescopes, the space between the rings appeared shrouded in dust.

Now, JWST’s infrared cameras have peered through the dust and found previously unseen stars and structure (SN: 7/11/22). The new image shows sites of intense star formation throughout the galaxy that were triggered by the collision’s aftereffects. Some of those new stars are forming in spokelike patterns between the central ring and the outer ring, a process that is not well understood.
Ring galaxies are rare, and galaxies with two rings are even more unusual. That strange shape means that the long-ago collision set up multiple waves of gas rippling back and forth in the galaxy left behind. It’s like if you drop a pebble in the bathtub, says JWST project scientist Klaus Pontoppidan of the Space Telescope Science Institute in Baltimore. “First you get this ring, then it hits the walls of your bathtub and reflects back, and you get a more complicated structure.”

The effect probably means that the Cartwheel Galaxy has a long road to recovery ahead — and astronomers don’t know what it will look like in the end.

As for the smaller galaxy that caused all this mayhem, it didn’t stick around to get its picture taken. “It’s gone off on its merry way,” Pontoppidan says.

How slow and steady lionfish win the race against fast prey

Lionfish certainly aren’t the fastest predators on the reef, but new research suggests that they can catch swift prey through pure tenacity, gliding slowly in pursuit until the perfect moment to strike.

The finding may help explain part of the lionfish’s impact as an invasive species, and reveal a key hunting strategy that other relatively slow predators use, researchers report August 2 in Proceedings of the Royal Society B.

Festooned with long striped spines, lionfish can make their surreal silhouettes disappear against a coral reef backdrop long enough to stalk and ambush small fish. But the predators also feed in open water where they’re more visible.
Curious about how the predators hunt in plain view, Ashley Peterson, a comparative biomechanist at the University of California, Irvine, and her colleagues placed red lionfish (Pterois volitans) in a tank and recorded them as they chased down a green chromis (Chromis viridis), a small reef fish.

In 14 of the 23 trials, the lionfish successfully gulped down their prey. They also had a high rate of strike success, capturing the chromis in 74 percent of the trials where the lionfish made a strike attempt.

On average, the chromis swam about twice as fast as the lionfish. But many still fell victim to what Peterson and biomechanist Matthew McHenry, also at the University of California, Irvine, call a persistent-predation strategy — the lionfish swim toward a chromis, aiming for its current position, not the direction to intercept its path. And the lionfish’s pursuit is steady and incessant, the team found.

“If they’re interested in something and they want to try to eat it, they just seem to not give up,” Peterson says.

In contrast, the prey fish does bursts of fast swimming along with short pauses.

“Over time, all those pauses add up and allow this lionfish to get closer and closer and closer,” Peterson says. Then the slightest mistake or bit of distraction can doom the prey to the lionfish’s suction-creating jaws.

“This is a good example of ‘slow and steady wins the race,’” says Bridie Allan, a marine ecologist at the University of Otago in Dunedin, New Zealand who was not involved in the research. It would be interesting to see how the unwavering chase plays out in the wild, where there are no spatial restrictions like in a tank, she says.

If lionfish do use the strategy in the wild and prey react similarly, it’s possible that the tactic could contribute to the destructive potential of their invasion in the Caribbean, Western Atlantic and the Mediterranean, where the fish are devouring native ocean animals and disrupting food webs (SN: 7/6/16). But other factors, such as the lionfish’s huge appetite or prolific reproduction, could be more influential on invasiveness.

The persistent-predation strategy may not be exclusive to lionfish, Peterson says. Other predatory fish groups with sluggish swimmers — like straw-shaped trumpetfish (Aulostomus spp.) — could also use it.

In a natural setting, prey that are dodging lionfish and other slow swimmers may have more places to hide, Peterson says. But there are inherent risks in a busy, distracting environment too. “If you’re near a reef or up against the coral, you could get pinned if you aren’t really paying attention,” she says. That’s when determined and hungry slowpokes may have the upper hand.

Spinal stimulation gives some people with paralysis more freedom

By his count, Michel Roccati is on his third life, at least. In the first, he was a fit young man riding his motorcycle around Italy. A 2017 crash in the hills near Turin turned him into the second man, one with a severe spinal cord injury that left him paralyzed from the waist down. Today, the third Michel Roccati works out in his home gym in Turin, gets around with a walker and climbs stairs to visit a friend in a second-story apartment. Today, he says, his life is “completely different than it was before.”

Roccati, age 31, is one of three men who received experimental spinal cord stimulators as part of a clinical trial. All three had completely paralyzed lower bodies. The results have been a stunning success, just as Roccati had hoped. “I fixed in my mind how I was at the end of the project,” he says. “I saw myself in a standing position and walking. At the end, it was exactly what I expected.”
The technology that Roccati and others use, described in the February Nature Medicine, is an implanted array of electrodes that sits next to the spinal cord below the spot severed by the injury. Electrical signals from the device replace the missing signals from the brain, prompting muscles to move in ways that allow stepping, climbing stairs and even throwing down squats in the gym.

Today, Roccati spends time working at the consulting company he owns with his brother and sharing his ongoing physical accomplishments with researchers. “Every week we get a WhatsApp from Michel doing something new,” says study coauthor Robin Demesmaeker, a neural engineer at NeuroRestore, a research and treatment center in Lausanne, Switzerland.
These results and others prove that, with the right technology, people with severe spinal cord injury may be able to stand up and walk again. It’s a remarkable development.

But the really big news in this area goes far beyond walking. Many people with spinal cord injuries deal with problems that aren’t as obvious as paralysis. Low blood pressure, sexual dysfunction and trouble breathing or controlling hands, arms, bladder and bowels can all be huge challenges for people with paralysis as they navigate their daily lives. “These are the things that actually matter to people with spinal cord injuries,” says John Chernesky, who has a spinal cord injury. He works at the nonprofit Praxis Spinal Cord Institute in Vancouver, where he makes sure the priorities and voices of people living with spinal cord injuries are heard and addressed in research.

By figuring out the language of the spinal cord, researchers hope to learn how to precisely fill in the missing commands, bridging the gap left by the injury. The work may pave the way to treat many of these problems flagged by patients as important.

“The research field is changing … embracing all these other aspects,” says neuroscientist Kim Anderson Erisman of MetroHealth Medical Center and Case Western Reserve University in Cleveland. Already, early clinical trials are tackling the less obvious troubles that come with spinal cord injuries. Some of the same scientists that helped Roccati recently showed that similar spinal cord stimulation eased a man’s chronic low blood pressure. Other researchers are improving bladder and bowel function with stimulation. Still more work is focused on hand movements. The technology, and the understanding of how to use it to influence the nerves in the spinal cord, is moving quickly.

Not coincidentally, the way the research is being conducted is shifting, too, says Anderson Erisman, who has a spinal cord injury. “Scientists know the textbook things about spinal cord injuries,” she says. “But that’s not the same thing as living one day in the life with a spinal cord injury.” Involving people with such injuries in studies — as true partners and collaborators, not just subjects — is pushing research further and faster. Such collaboration, she says, “will only make your program stronger.”

These efforts are in the early stages. The stimulators are not available to the vast majority of people who might benefit from them. Only a handful of people have participated in these intense clinical trials so far. It’s unclear how well the results will hold up in larger trials with a greater diversity of volunteers. Also unclear is how attainable the technology will be for people who need it. For now, the research often requires large teams of experts, typically in big cities, with patients needing surgery and months of training the body to respond.

Still, the promise of spinal cord stimulation extends beyond spinal cord injuries. Stimulating nerves on the spinal cord could help people with symptoms from strokes, Parkinson’s disease, multiple sclerosis, cerebral palsy and other disorders in which signals between the brain and body get garbled. Initially, “hardly anyone wanted to believe these [improvements] were happening,” says V. Reggie Edgerton, an integrative biologist at the University of Southern California’s Neurorestoration Center and the Rancho Los Amigos Rehabilitation Center in Downey, Calif. “But now, they’re happening so regularly that it’s undeniable.”

A turnaround
Not so long ago, a serious spinal cord injury was a death sentence. “Prior to World War II, the life expectancy of a person with a spinal cord injury was measured in days or weeks,” Chernesky says. If the injury didn’t kill a person directly, they’d often succumb to respiratory distress or blood poisoning from a bladder infection. “If you lived six months, that was impressive,” he says.

The spinal cord ferries signals between brain and body. Signals from the brain tell leg muscles to contract for a step, blood vessels to expand and the bladder to hold steady until a bathroom is within reach. Signals from the body to the brain carry sensations of moving, pain and touch. When the spinal cord is injured, as it is for an estimated 18,000 or so people each year in the United States alone, these signals are blocked.
Researchers have long dreamed of repairing the damage by bridging the gap, perhaps with stem cells or growth factors that can beckon nerve cells to grow across the scar. The idea of using electricity to stimulate nerves below the site of the injury came, in part, from an accidental observation. In the mid-1970s, scientists were testing spinal cord stimulation as a treatment for severe and chronic pain. One participant happened to be a woman who was paralyzed from multiple sclerosis, a disease in which the body attacks its own nerves. With the device implanted on her spinal cord to ease pain, she was able to move again. That surprising discovery helped spark interest in spinal cord stimulation as a way to restore movement.

In 2011, researchers at the University of Louisville in Kentucky restored the ability to stand to a 23-year-old man with paraplegia. In 2018, that group and two others reported even greater strides in spinal stimulation: People with severe spinal cord injuries could step and walk with assistance (SN: 12/22/18 & 1/5/19, p. 30).

Earlier this year, Demesmaeker and his colleagues, including Grégoire Courtine of the Swiss Federal Institute of Technology in Lausanne, published the achievements of Roccati and two other men. All three men had been unable to move their lower limbs or feel any sensations there.

Most previous studies had relied on an electrode array designed and approved by the U.S. Food and Drug Administration to treat chronic pain. That device has electrodes that are implanted along the spinal cord, where their electrical jolts can ease long-term pain in the back and legs. But Roccati and the two other men received a specially designed device that was slightly longer and wider than that earlier device, able to cover more of the spinal cord’s nerve roots and provide more stimulation options.

Several weeks after surgery, the men visited the laboratory in Lausanne to start searching for the optimal stimulation settings. The timing, pattern and strength of the electrode signals were adjusted to allow Roccati to move. “We found a good sequence with the engineers that allowed me to stand up and see my body standing in the mirror in front of me,” Roccati says. “It was a very emotional moment. A standing ovation appeared from everyone in there.”

That first day, he took steps with the stimulation while being supported by a harness. That quick improvement is important, says biomedical engineer Ismael Seáñez of Washington University in St. Louis. “From day one, you can start training.” After months of intense practice (four to five sessions a week for one to three hours at a time), Roccati could walk without the harness, using only a walker.

The men in the trial have all been getting stronger, even when the stimulation is off. That suggests that there’s some sort of repair happening in the body, perhaps due to stronger neural pathways in the spinal cord. Just how the stimulation repairs the spinal cord is one of the big remaining mysteries.

“It’s exciting to see,” Seáñez says. “But it’s a first step in all of the different challenges faced by people with spinal cord injuries.”
Signaling blood vessels
One important problem with paralysis is low blood pressure. When the spinal cord is damaged, the signals that keep blood vessels constricted and blood pressure normal can get lost. Low blood pressure can leave people mentally foggy, exhausted and prone to fainting, not ideal conditions for physical rehab work. Blood pressure can also rise or fall quickly, upping the risk for stroke and heart attack. That’s a huge problem, says Aaron Phillips, who studies the physiology of the nervous system at the University of Calgary in Canada. “Blood pressure is one of the vital signs of life,” he says.

So Phillips, Courtine and colleagues decided to implant a spinal cord stimulator to see if it would help a man who had low blood pressure due to a spinal cord injury. When the machine was on, his blood pressure rose toward normal levels, the researchers reported last year in Nature. When the stimulation was turned off, the man’s blood pressure dropped.

The scientists homed in on an area in the mid-back, just around thoracic segment 11 in the human spine. That spot had the biggest effect on the man’s blood pressure. “We now know that there’s a key area in the spinal cord that, when stimulated, controls neural circuits and the connected blood vessels to elevate and decrease blood pressure,” Phillips says.

The system the researchers developed operated like a thermostat with a set point. In experiments with the man on a tilting table, monitors sensed low blood pressure when the table mimicked standing up. That triggered the stimulators, which in turn told the blood vessels to bring the pressure back up to an acceptable level.

The results represent “a huge pinnacle of my career,” Phillips says. But many challenges remain. The system used in the study in Nature needs tweaking, and the long-term effects of such stimulation aren’t known. Phillips and his colleagues hope to answer these questions. With funding from DARPA, a U.S. Department of Defense agency that invests in breakthrough technologies, the team is working on a wireless blood pressure monitor, and an upcoming clinical trial aims to enroll about 20 people with spinal cord injuries that affect their blood pressure.

Patient priorities
In 2004, Anderson Erisman and her colleagues asked people with spinal cord injuries to share their priorities for regaining function. For people with quadriplegia, who have impairments from the neck down, hand and arm function were most important. For people with paraplegia, who have use of their arms and upper body, sexual function was the highest priority. Both groups emphasized the desire for restored bladder and bowel function, Anderson Erisman and colleagues reported in the Journal of Neurotrauma. Walking was not at the top of either group’s wish list.

That’s no surprise to Chernesky, who uses a wheelchair. “The general population looks at people with spinal cord injuries rolling around in wheelchairs, and they say, ‘Oh, poor bugger. I bet he wishes he could walk,’ ” he says. “They have no idea that quite rapidly after an injury, walking becomes a lower priority.”

Chernesky himself recently participated in a clinical trial designed to externally stimulate the cervical spine, in his neck, to improve arm and hand movements. The device he tested sent signals to the spinal cord through the skin — a less invasive approach than surgery, but one that may sacrifice some specificity compared with implanted versions. Throughout that process, Chernesky noticed improvements in energy, sleep, strength, core stability and movement of both upper and lower limbs.
Other scientists are working on similar ways to externally stimulate the spinal cord to improve people’s autonomic nervous system. That system keeps your blood pressure steady, makes you sweat when it’s hot and tells you when you need to head to a bathroom.

In studies at the University of Southern California and elsewhere, Edgerton and colleagues have recently shown that external stimulation improved bowel function. He and others have also seen stimulators improve bladder function in people with spinal cord injuries and strokes. “We know some subjects can now feel when their bladder is full,” says Edgerton, who started a company called SpineX in 2019 to develop the technology further. That newfound sensation gives people enough time to get to the bathroom. “This doesn’t happen overnight, and it doesn’t happen in every individual,” he cautions. “But it happens a lot.”

Getting past the hype
The next phase of research will be boring — in the best possible way. Large, standardized studies will need to address some mundane but crucial questions, such as who might benefit from stimulation, how much improvement can be made for certain symptoms and whether the therapy causes any extra trouble for some people. “This type of technology will go from a very exciting proof of concept to standard clinical care,” Seáñez predicts.

Over his nearly 30 years of living with a spinal cord injury, Chernesky has witnessed enough so-called scientific breakthroughs to be skeptical. He’s immune to hype. But he admits that he’s excited by this moment. “Because now we can reverse paralysis,” he says. That doesn’t mean people are going to suddenly be tap dancing like Fred Astaire or playing a Chopin concerto anytime soon, he’s quick to add. “But every little bit matters.”

Roccati, for one, no longer has to recruit friends to carry him in his wheelchair up stairs to socialize. He feels more energetic. He is working on his summer six-pack abs. He has transformed, again, into someone new. “Now, after the implant, I am another type of person,” he says, a more optimistic version of himself.
This technology is still a long way from helping everyone who might benefit. Still, these stimulators hold great promise. “I am quite hopeful, almost certain, that these devices are going to become available, and there will be a lot of people buying them,” Chernesky says. “When you have nothing, and you can get a little bit back — how good is that?”

An hour after pigs’ deaths, an artificial system restored cellular life

Call it cellular life support for dead pigs. A complex web of pumps, sensors and artificial fluid can move oxygen, nutrients and drugs into pigs’ bodies, preserving cells in organs that would otherwise deteriorate after the heart stops pumping.

The finding, described August 3 in Nature, is preliminary, but it hints at new ways to keep organs in a body healthy until they can be used for transplantation.

In earlier work, scientists built a machine they named BrainEx, which kept aspects of cellular life chugging along in decapitated, oxygen-deprived pig brains (SN: 4/17/19). The new system, called OrganEx, pushes the approach to organs beyond the brain.
“We wanted to see if we could replicate our findings in other damaged organs across the body, and potentially open the door for future transplantation studies,” says Nenad Sestan, a neuroscientist at Yale University School of Medicine.

OrganEx aims to do the job of hearts and lungs by pumping an artificial fluid throughout pig bodies. Mixed in a 1–1 ratio with the animals’ own blood, the lab-made fluid has ingredients that provide fresh oxygen and nutrients, prevent clots and protect against inflammation and cell death.

Anesthetized pigs were put into cardiac arrest and then left alone for an hour. Then some pigs were placed on an existing medical system, called extracorporeal membrane oxygenation, or ECMO. This adds oxygen to the pigs’ own blood and pumps it into their body. Other pigs received the OrganEx treatment.

Compared with ECMO, OrganEx provided more fluid to tissues and organs, the researchers found. Fewer cells died, and some tissues, including kidneys, even showed cellular signs of repairing themselves from the damage done after the heart stopped.

A similar system might one day be useful for protecting human organs destined to be donated. But for now, “there is still lots of work to be done in our animal model,” Sestan says.

An award-winning photo captures a ‘zombie’ fungus erupting from a fly

Sometimes a photo is literally a matter of life, death — and zombies.

This haunting image, winner of the 2022 BMC Ecology and Evolution photography competition, certainly fits that description. It captures the fruiting bodies of a parasitic fungus, emerging from the lifeless body of an infected fly in the Peruvian rainforest.

The fungus-infested fly was one of many images submitted to the contest from all over the world, aiming to showcase the beauty of the natural world and the challenges it faces. The journal revealed the winners August 18.
Roberto García-Roa, a conservation photographer and evolutionary biologist at the University of Valencia in Spain, took the winning photo while visiting the Tambopata National Reserve, a protected habitat in the Amazon.

The fungus erupting from the fly belongs to the genus Ophiocordyceps, a diverse collection of parasitic fungi known as “zombie fungi,” due to their ability to infect insects and control their minds (SN: 7/17/19).

“There is still much to unravel about the diversity of these fungi as it is likely that each insect species infected succumbs to its own, specialized fungus,” says Charissa de Bekker, an expert in parasitic fungi at Utrecht University in the Netherlands.

First, spores of the fungus land on the ill-fated fly. So begins the manipulative endgame. The spores infiltrate the fly’s exoskeleton before infecting its body and eventually hijacking its mind. Once in control, the fungus uses its new powers of locomotion to relocate to a microclimate more suitable to its own growth — somewhere with the right temperature, light and moisture.

Fungus and fly then bide their time until the fly dies, becoming a food source for the fungus to consume. Fruiting bodies work their way out of the fly, filled with spores that are released into the air to continue the macabre cycle in a new, unsuspecting host. It is a “conquest shaped by thousands of years of evolution,” García-Roa said in a statement announcing the winners.

Research into the molecular aspects of fungal mind control is under way, De Bekker says, including in her own lab. “These fungi harbor all sorts of bioactive chemicals that we have yet to characterize and that could have novel medicinal and pest control applications.”

‘The Five-Million-Year Odyssey’ reveals how migration shaped humankind

Archaeologist Peter Bellwood’s academic odyssey wended from England to teaching posts halfway around the world, first in New Zealand and then in Australia. For more than 50 years, he has studied how humans settled islands from Southeast Asia to Polynesia.

So it’s fitting that his new book, a plain-English summary of what’s known and what’s not about the evolution of humans and our ancestors, emphasizes movement. In The Five-Million-Year Odyssey, Bellwood examines a parade of species in the human evolutionary family — he collectively refers to them as hominins, whereas some others (including Science News) use the term hominids (SN: 9/15/21) — and tracks their migrations across land and sea. He marshals evidence indicating that hominids in motion continually shifted the direction of biological and cultural evolution.
Throughout his tour, Bellwood presents his own take on contested topics. But when available evidence leaves a debate unresolved, he says so. Consider the earliest hominids. Species from at least 4.4 million years ago or more whose hominid status is controversial, such as Ardipithecus ramidus, get a brief mention. Bellwood renders no verdict on whether those finds come from early hominids or ancient apes. He focuses instead on African australopithecines, a set of upright but partly apelike species thought to have included populations that evolved into members of our own genus, Homo, around 2.5 million to 3 million years ago. Bellwood hammers home the point that stone-tool making by the last australopithecines, the first Homo groups or both contributed to the evolution of bigger brains in our ancestors.

The action speeds up when Homo erectus becomes the first known hominid to leave Africa, roughly 2 million years ago. Questions remain, Bellwood writes, about how many such migrations occurred and whether this humanlike species reached distant islands such as Flores in Indonesia, perhaps giving rise to small hominids called hobbits, or Homo floresiensis (SN: 3/30/16). What’s clear is that H. erectus groups journeyed across mainland Asia and at least as far as the Indonesian island of Java.

Intercontinental migrations flourished after Homo sapiens debuted, around 300,000 years ago in Africa. Bellwood regards H. sapiens, Neandertals and Denisovans as distinct species that interbred in certain parts of Asia and Europe. He suggests that Neandertals disappeared around 40,000 years ago as they mated with members of more numerous H. sapiens populations, leaving a genetic legacy in people today. But he does not address an opposing argument that different Homo populations at this time, including Neandertals, were too closely related to have been separate species and that it was intermittent mating among these mobile groups that drove the evolution of present-day humans (SN: 6/5/21).

Bellwood gives considerable attention to the rise of food production and domestication in Europe and Asia after around 9,000 years ago. He builds on an argument, derived from his 2004 book First Farmers, that expanding populations of early cultivators migrated to new lands in such great numbers that they spread major language families with them. For instance, farmers in what’s now Turkey spread Indo-European languages into much of Europe sometime after roughly 8,000 years ago, Bellwood contends.

He rejects a recent alternative proposal, based on ancient DNA evidence, that horse-riding herders of Central Asia’s Yamnaya culture brought their traditions and Indo-European tongues to Europe around 5,000 years ago (SN: 11/15/17). Too few Yamnaya immigrated to impose a new language on European communities, Bellwood says. Similarly, he argues, ancient Eurasian conquerors, from Alexander the Great to Roman emperors, couldn’t get speakers of regional languages to adopt new ones spoken by their outnumbered military masters.

Bellwood rounds out his evolutionary odyssey with a reconstruction of how early agricultural populations expanded through East Asia and beyond, to Australia, a string of Pacific islands and the Americas. Between about 4,000 and 750 years ago, for instance, sea-faring farmers spread Austronesian languages from southern China and Taiwan to Madagascar in the west and Polynesia in the east. Precisely how they accomplished that remarkable feat remains a puzzle.

Disappointingly, Bellwood doesn’t weigh in on a recent archaeological argument that ancient societies were more flexible and complex than long assumed (SN: 11/9/21). On the plus side, his evolutionary odyssey moves along at a brisk pace and, like our ancestors, covers a lot of ground.