A praying mantis depends on precision targeting when hunting insects. Now, scientists have identified nerve cells that help calculate the depth perception required for these predators’ surgical strikes.
In addition to providing clues about insect vision, the principles of these cells’ behavior, described June 28 in Nature Communications, may also lead to advances in robot vision or other automated systems.
So far, praying mantises are the only insects known to be able to see in 3-D. In the new study, neuroscientist Ronny Rosner of Newcastle University in England and colleagues used a tiny theater that played praying mantises’ favorite films — moving disks that mimic bugs. The disks appeared in three dimensions because the insects’ eyes were covered with different colored filters, creating minuscule 3-D glasses. As a praying mantis watched the films, electrodes monitored the behavior of individual nerve cells in the optic lobe, a brain structure responsible for many aspects of vision. There, researchers found four types of nerve cells that seem to help merge the two different views from each eye into a complete 3-D picture, a skill that human vision cells use to sense depth, too.
One cell type called a TAOpro neuron possesses three elaborate, fan-shaped bundles that receive incoming visual information. Along with the three other cell types, TAOpro neurons are active when each eye’s view of an object is different, a mismatch that’s needed for depth perception.
The details of the various types of nerve cells, and how they might receive, combine and send visual information, suggest that these insects’ vision may be more sophisticated than some scientists had thought, the team writes. And the principles guiding praying mantis depth perception may be useful to researchers working on improving machine vision, perhaps allowing artificial systems to better sense the depths of objects.
A new biomaterial delivered to the heart soon after a heart attack can heal damaged tissue from the inside out.
Heart attacks kill cardiac muscle tissue, scarring the heart and leaving permanent damage after just six hours. The damage prevents the heart from functioning properly. If there was a way to begin healing damaged tissue soon after a heart attack, doctors could prevent scar tissue from developing.
“In an ideal world, you treat a patient immediately when they’re having a heart attack to try to salvage some of the tissue and promote regeneration,” says Karen Christman, a bioengineer at the University of California, San Diego. The pursuit of this ideal inspired Christman, along with a team of researchers, to develop the biomaterial. In rodents and pigs, it appears to repair tissue damage and reduce inflammation directly after a heart attack, Christman and colleagues report December 29 in Nature Biomedical Engineering.
“I think it has a lot of potential,” Vimala Bharadwaj, a biomedical scientist at Stanford University who was not involved in the research. The paper “is definitely good proof of concept for what they’re trying to do.”
Previously, researchers found that stem cells derived from body fat can be used to heal bones, muscles and the heart (SN: 3/9/16). Christman wanted to work with the extracellular matrix, the lattice of proteins that provide structural support to the cells in cardiac muscle tissue. Like stems cells, it has regenerative abilities but is much less expensive, she says.
In 2009, Christman’s team produced a hydrogel using particles from this matrix. Trials in rats and later in humans showed that the material bonded to damaged areas and promoted cell repair and growth. However, due to relatively large particles of the hydrogel, it could be delivered to the heart only via a needle.
“Poking the heart with a needle could set off an arrhythmia,” says Christman. To use this treatment, doctors would need to wait a few weeks until the heart is more stable and the chance of these irregular heartbeats decreases. And that would be too late to prevent scarring.
The team took the previously created hydrogel, sifted out the larger particles with a centrifuge so only nanoparticles remained, and added water to dilute the mixture. That created a material thin enough to deliver to heart blood vessels intravenously. Based on the nanoparticles’ size, the team expected the mixture would slip through any gaps in cardiac blood vessels caused by the heart attack and adhere to the surrounding tissue. Once there, it would create a protective barrier while the heart healed.
Instead, animal experiments showed that the extracellular matrix material bound to the leaky vessels, preventing some inflammatory cells from moving into the heart tissue in the first place and causing further damage. The material reduced inflammation in the heart and stimulated the healing process by encouraging cell growth, the team reports.
Further safety studies will be needed to get the biomaterial ready for clinical trials. The first trial in humans will most likely be for repairing cardiac tissue post–heart attack. “A lot of my motivation is moving things out of the lab, actually into the real world,” Christman says.
Another real-world application of the biomaterial could be treatment for leaky blood vessels in other hard-to-access organs, including in the brain after a traumatic injury, Christman notes.
While Bharadwaj finds that application potentially promising, she says tests are needed to see whether the biomaterial improves headaches and cognitive or memory deficits in the brain after a traumatic injury. That’s needed to gauge whether it really is an effective TBI treatment.
As early as 252 million years ago, some plants may have curled up their leaves at night for a cozy “sleep.”
Fossilized leaves of two now-extinct Gigantonoclea species bear signs of nyctinasty, or circadian rhythmic folding at night, researchers report February 15 in Current Biology. That would make these specimens the first known fossilized examples of this curious plant behavior, the team says.
The two leaf fossils were discovered in a rock layer in southwestern China that dates to between 259 million and 252 million years ago. In both species, the leaves were broad, with serrated edges. But most curiously, they bear oddly symmetrical holes. Insects made those holes while feeding on the leaves while they were folded, say paleontologist Zhuo Feng of Yunnan University in Kunming, China and colleagues. Similar symmetrical patterns of insect damage in leaf fossils can be used to distinguish folding behavior from leaves that might have shriveled as the plant died, the team says.
Modern plants, including many in the legume family such as the orchid tree, that fold and unfold their leaves use specialized cells called pulvinus cells, which act somewhat like muscles (SN: 2/3/23). By shifting water from one part of the leaf to another, the cells can bloat or deflate, allowing the leaves to fold or curl.
These cells would be at the base of the leaves, which weren’t preserved in the fossils, so it’s not possible to say whether these ancient plants also had pulvinus cells, the team says. Although it’s also hard to prove this was nighttime behavior, the leaves would also have had to be folded long enough for insects to do their munching. But the find does suggest that such leaf folding emerged independently in different plant lineages: Nearly all the modern plants that do this are angiosperms, or flowering plants. But Gigantonoclea plants were gymnosperms, seed-producing plants such as conifers and ginkgos.
A focus on family might be the key to personal well-being.
Surveys in the social sciences, such as those measuring happiness or health, tend to focus on the smallest unit: the individual. But two new studies, each surveying over 10,000 people worldwide, show that primary unit of analysis may need scaling up. One study suggests that people adhere to public health guidelines less to protect themselves than their loved ones. And the other study provides an explanation for why that may be the case: People the world over prioritize family happiness over their own. Neither research team defined the term “family,” instead allowing respondents to interpret the term as they saw fit. As such, the results suggest that the exact nature of family, whether nuclear, blood-related or extended, does not matter.
The findings have important implications for society, says Karen Bogenschneider, a family policy expert at the University of Wisconsin–Madison who was not involved with either study. That’s because policy makers occasionally rely on research findings to develop programs such as those aimed at reducing substance abuse or inequality. When researchers frame societal issues in terms of the individual or community, so too do policy makers. And those programs may be less effective as a result.
For instance, several studies in the past couple decades have shown that including family members in addiction treatment programs lowers the addict’s risk of relapse and improves family relationships.
Moreover, these studies challenge the assumption that individualism has turned the self into the most important unit of survival (SN: 10/7/19).
Family bonds drove individuals to adopt pandemic-related health behaviors The idea that policy makers can target family to change behavior comes as no surprise to Martha Newson, an anthropologist at Kent University in England. For years, Newson has studied a concept known as fusion, where an individual becomes so enmeshed in a larger social unit that she or he is willing to sacrifice personal well-being, or even survival, for the group (SN: 6/23/16).
At the onset of the pandemic, Newson and her team began studying how social fusion might be influencing behavior around the world during the pandemic. From March to May 2020, over 13,000 participants from 122 countries were shown a sequence of five pictures, each with two circles, one for the self and the other for a given group such as family, country or all of humankind. In the first picture, the circles are far apart, but in subsequent pictures they grow closer and closer together until they fully overlap. Participants had to select one of the five pictures to indicate their level of fusion with the group. A participant had to select the fully overlapping circles to be considered fused to the group.
Participants also filled out scales to indicate how much they had performed a given public health action, such as social distancing or masking, in the previous week.
Participants who were fused to family were overrepresented among those reporting strong adherence to public health guidelines, Newson and colleagues reported January 13 in Science Advances. For instance, despite representing roughly a quarter of the participant pool, participants with strong family bonds constituted three-quarters of those who reported following social distancing guidelines. And almost half of participants with strong family bonds reported frequent handwashing compared with about one-third of participants with weaker family bonds.
Humans evolved in small-scale societies, Newson says. “When we have crises … these smaller units remain very important.”
On average, people value family happiness more than their own Meanwhile, another group of researchers had begun to question the widely accepted belief that many happy individuals sum up to a happy society. That idea originated in the West, and has often been treated as universal, says Kuba Krys, a cross-cultural psychologist at the Polish Academy of Sciences in Warsaw.
But research over the years has indicated that non-Westerners may not value personal happiness as much as people in the West. For instance, outside the West, people tend to see happiness as more interdependent, or grounded in harmony and balance with others, than independent, or grounded in the self.
If happiness exists at least partially outside the individual, then Krys and his team wondered what unit researchers should study. They looked to family.
The team had roughly 13,000 participants from 49 countries indicate how much the perfect or ideal person would agree with statements in two commonly used surveys of well-being. Statements appeared both in the standard “I” framing and in a new family framing. For instance, participants reflected on how the ideal person would respond to both the statements, “In most ways, my life is close to ideal” and “In most ways, the life of my family is close to ideal.”
Nearly half of the participants valued family well-being over personal well-being, while less than a third preferred their own happiness, the team reports in an upcoming paper in the Journal of Cross-Cultural Psychology. Moreover, participants in even the most individualistic countries, including the United States, valued family, on average, more than self. The word “family” has become associated with conservativism, Krys says. But family remains central to people’s lives, regardless of geography or political affiliation. “The shape of family has changed but family as an idea, as a basic unit, has not changed,” he says. “I would advise progressives … not to be afraid of touching on family topics.”
Bogenschneider’s research backs up this point. In a study of more than 200 state legislators, she and colleagues found that while abortion and same-sex marriage remain highly polarized, policy makers tend to view other family issues, such as those involving domestic violence, juvenile crime or teen pregnancy, as largely bipartisan.
This suggests that issues that aren’t typically centered around family, such as climate change or inequality, could be framed in terms of family to garner wider support, Bogenschneider says. Researchers who are seeking to translate their findings into policy and advocates who are advancing particular causes could, she adds, “elevate policy makers’ interest in those issues by focusing on families and family contributions.”
It turns out that certain behaviors in domestic cats could be telltale signs that an interaction is friendly, aggressive or something in between, researchers report January 26 in Scientific Reports.
“It is a question we hear a lot from cat owners,” says cat behavior expert Mikel Delgado of Feline Minds, a cat behavior consulting company in Sacramento, Calif., who was not involved in the study. “So I was excited to see that researchers are taking on this topic.” Scientists have studied cats’ social relationships — both with other cats and humans — but it can be tricky to tell whether two cats are playing or fighting, says veterinarian and cat behavior researcher Noema Gajdoš-Kmecová of the University of Veterinary Medicine and Pharmacy in Košice, Slovakia (SN: 9/23/19).
Sometimes cat owners miss the signs of a tense relationship because they think their pets are just playing, which can lead to stress and illness in the animals, she says. Other times, owners rehome their cats after incorrectly assuming their pets are fighting.
To assess and categorize interactions, Gajdoš-Kmecová and colleagues watched about 100 videos of different cats interacting in pairs. After viewing around one-third of the videos, Gajdoš-Kmecová identified six types of behaviors, including wrestling and staying still. She then watched all of the videos and noted how often each cat exhibited one of the specified behaviors, and for how long. By running statistical analyses on the behaviors, she pinpointed three types of interactions between the cat pairs: playful, aggressive and intermediate.
To confirm the outcome, other members of the team also watched the videos and classified each interaction between felines.
Some clear connections emerged. Quietly wrestling, for instance, suggested playtime, whereas chasing and vocalizations, like growling, hissing or gurgling, implied aggressive encounters.
Intermediate interactions had elements of both playful and aggressive encounters, but especially included prolonged activity of one cat toward the other, such as pouncing on or grooming its fellow feline. These in-between encounters could hint that one cat wants to keep playing while the other doesn’t, with the more playful cat gently nudging to see if its partner wants to continue, the authors say. This work provides initial insights into cat interactions, Gajdoš-Kmecová says, but it’s just the start. In the future, she plans to study more subtle behaviors, like ear twitches and tail swishes. Both Gajdoš-Kmecová and Delgado also stress that one contentious encounter doesn’t necessarily signal a cat-astrophic relationship.
“This is not just about one interaction,” Gajdoš-Kmecová says. Owners “really should look into the different, multiple interactions in multiple periods of life of the cats and then put it into context.”
The night sky has been brightening faster than researchers realized, thanks to the use of artificial lights at night. A study of more than 50,000 observations of stars by citizen scientists reveals that the night sky grew about 10 percent brighter, on average, every year from 2011 to 2022.
In other words, a baby born in a region where roughly 250 stars were visible every night would see only 100 stars on their 18th birthday, researchers report in the Jan. 20 Science. The perils of light pollution go far beyond not being able to see as many stars. Too much brightness at night can harm people’s health, send migrating birds flying into buildings, disrupt food webs by drawing pollinating insects toward lights instead of plants and may even interrupt fireflies trying to have sex (SN: 8/2/17; SN: 8/12/15).
“In a way, this is a call to action,” says astronomer Connie Walker of the National Optical-Infrared Astronomy Research Laboratory in Tucson. “People should consider that this does have an impact on our lives. It’s not just astronomy. It impacts our health. It impacts other animals who cannot speak for themselves.”
Walker works with the Globe at Night campaign, which began in the mid-2000s as an outreach project to connect students in Arizona and Chile and now has thousands of participants worldwide. Contributors compare the stars they can see with maps of what stars would be visible at different levels of light pollution, and enter the results on an app.
“I’d been quite skeptical of Globe at Night” as a tool for precision research, admits physicist Christopher Kyba of the GFZ German Research Centre for Geosciences in Potsdam. But the power is in the sheer numbers: Kyba and colleagues analyzed 51,351 individual data points collected from 2011 to 2022.
“The individual data are not precise, but there’s a whole lot of them,” he says. “This Globe at Night project is not just a game; it’s really useful data. And the more people participate, the more powerful it gets.”
Those data, combined with a global atlas of sky luminance published in 2016, allowed the team to conclude that the night sky’s brightness increased by an average 9.6 percent per year from 2011 to 2022 (SN: 6/10/16).
Most of that increase was missed by satellites that collect brightness data across the globe. Those measurements saw just a 2 percent increase in brightness per year over the last decade. There are several reasons for that, Kyba says. Since the early 2010s, many outdoor lights have switched from high-pressure sodium lightbulbs to LEDs. LEDs are more energy efficient, which has environmental benefits and cost savings.
But LEDs also emit more short-wavelength blue light, which scatters off particles in the atmosphere more than sodium bulbs’ orange light, creating more sky glow. Existing satellites are not sensitive to blue wavelengths, so they underestimate the light pollution coming from LEDs. And satellites may miss light that shines toward the horizon, such as light emitted by a sign or from a window, rather than straight up or down.
Astronomer and light pollution researcher John Barentine was not surprised that satellites underestimated the problem. But “I was still surprised by how much of an underestimate it was,” he says. “This paper is confirming that we’ve been undercounting light pollution in the world.”
The good news is that no major technological breakthroughs are needed to help fix the problem. Scientists and policy makers just need to convince people to change how they use light at night — easier said than done.
“People sometimes say light pollution is the easiest pollution to solve, because you just have to turn a switch and it goes away,” Kyba says. “That’s true. But it’s ignoring the social problem — that this overall problem of light pollution is made by billions of individual decisions.”
Some simple solutions include dimming or turning off lights overnight, especially floodlighting or lights in empty parking lots.
Kyba shared a story about a church in Slovenia that switched from four 400-watt floodlights to a single 58-watt LED, shining behind a cutout of the church to focus the light on its facade. The result was a 96 percent reduction in energy use and much less wasted light , Kyba reported in the International Journal of Sustainable Lighting in 2018. The church was still lit up, but the grass, trees and sky around it remained dark.
“If it was possible to replicate that story over and over again throughout our society, it would suggest you could really drastically reduce the light in the sky, still have a lit environment and have better vision and consume a lot less energy,” he says. “This is kind of the dream.”
Barentine, who leads a private dark-sky consulting firm, thinks widespread awareness of the problem — and subsequent action — could be imminent. For comparison, he points to a highly publicized oil slick fire on the Cuyahoga River, outside of Cleveland, in 1969 that fueled the environmental movement of the 1960s and ’70s, and prompted the U.S. Congress to pass the Clean Water Act.
“I think we’re on the precipice, maybe, of having the river-on-fire moment for light pollution,” he says.
The Arctic today is a hostile place for most primates. But a series of fossils found since the 1970s suggest that wasn’t always the case.
Dozens of fossilized teeth and jaw bones unearthed in northern Canada belonged to two species of early primates — or at least close relatives of primates — that lived in the Arctic around 52 million years ago, researchers report January 25 in PLOS ONE. These remains are the first primate-like fossils ever discovered in the Arctic and tell of a groundhog-sized animal that may have skittered across trees in a swamp that once existed above the Arctic Circle. The Arctic was significantly warmer during that time. But creatures still had to adapt to extreme conditions such as long winter months without sunlight. These challenges make the presence of primate-like creatures in the Arctic “incredibly surprising,” says coauthor Chris Beard, a paleontologist at the University of Kansas in Lawrence. “No other primate or primate relative has ever been found this far north so far.”
Between frigid temperatures, limited plant growth and months of perpetual darkness, living in the modern Arctic isn’t easy. This is especially true for primates, which evolved from small, tree-dwelling creatures that largely fed on fruit (SN: 6/5/13). To this day, most primates — humans and few other outliers like Japan’s snow monkeys excepted — tend to stick to tropical and subtropical forests, largely found around the equator.
But these forests haven’t always been confined to their present location. During the early Eocene Epoch, which started around 56 million years ago, the planet underwent a period of intense warming that allowed forests and their warm-loving residents to expand northward (SN: 11/3/15).
Scientists know about this early Arctic climate in part because of decades of paleontological work on Ellesmere Island in northern Canada. These digs revealed that the area was once dominated by swamps not unlike those found in the southeastern United States today. This ancient, warm, wet Arctic environment was home to a wide array of heat-loving animals, including giant tapirs and crocodile relatives. For the new study, Beard and his colleagues examined dozens of teeth and jawbone fossils found in the area, concluding that they belong to two species, Ignacius mckennai and Ignacius dawsonae. These two species belonged to a now-extinct genus of small mammals that was widespread across North America during the Eocene. The Arctic variants probably made their way north as the planet warmed, taking advantage of the new habitat opening up near the poles.
Scientists have long debated whether this lineage can be considered true primates or whether they were simply close relatives. Regardless, it’s still “really weird and unexpected” to find primates or their relatives in the area, says Mary Silcox, a vertebrate paleontologist at the University of Toronto Scarborough.
For one thing, Ellesmere Island was already north of the Arctic Circle 52 million years ago. So while conditions may have been warmer and wetter, the swamp was plunged into continuous darkness during the winter months.
Newly arrived Ignacius would have had to adapt to these conditions. Unlike their southern kin, the Arctic Ignacius had unusually strong jaws and teeth suited to eating hard foods, the researchers found. This may have helped these early primates feed on nuts and seeds over the winter, when fruit wasn’t as readily available.
This research can shed light on how animals can adapt to live in extreme conditions. “Ellesmere Island is arguably the best deep time analog for a mild, ice-free Arctic,” says Jaelyn Eberle, a vertebrate paleontologist at the University of Colorado Boulder.
Studying how plants and animals adapted to this remarkable period in Arctic history, Beard says, could offer clues to the Arctic’s future residents.
