The Liberty Bell, with its famous crack, hasn't been rung in 180 years, but that hasn't stopped scientists from pondering what the bell might have sounded like when tolling. In honor of the nation's 250th anniversary, researchers at Penn State University have modeled its acoustic properties, drawing on data collected from one of the bell's replicas. The work was first presented at a meeting of the Acoustical Society of America in Philadelphia earlier this year, followed by an article in Physics Today.

Historians aren't sure exactly when the Liberty Bell acquired its distinctive crack, just that it occurred sometime between 1817 and 1846. An 1846 account in the Public Ledger described the ringing of the bell on February 23 that year and mentioned that the bell had developed a crack, which someone had attempted to fix by filing the sides down. But it didn't work: The February 23 ringing extended the crack even more, so much so that "the old Independence Bell ... now hangs in the great steeple irreparably cracked and forever dumb." Nobody has heard it ring since.

This wasn't the first time the bell had cracked; the rim cracked shortly after it arrived in Philadelphia in 1752, the first time the clapper struck while testing the sound. It was recast by two local foundry workers, John Pass and John Stow, not once but twice, because the first recast produced a sound that one bystander likened to coal scuttles banging together.

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Honey bees are known to leave their stingers embedded in tender flesh once they sting you and fly away. Scientists have now determined that the stinger is able to continue pumping venom into its unfortunate victim even after the bee flies away, thanks to a unique double-piston pump-like mechanism, according to a new paper published in the Proceedings of the National Academy of Sciences.

Different species have evolved different mechanisms for delivering venom, which involves piercing the skin and then pumping venom from a gland or reservoir. Spiders, for instance, have muscles surrounding their venom glands, which contract and eject venom through hollow fangs. Bees, wasps, and ants deliver venom via their stingers, either by contracting muscles around the venom reservoir or through stiff elements called lancets working together to pump venom.

Honey bees (Apis mellifera) add a unique feature: Worker bees fly away after inserting their stingers in the target, leaving the stinger behind. The stinger continues to penetrate the tissue and pump venom on its own, a rare phenomenon known as autotomy. A honey bee's stinger has three main interlocking elements that form the venom canal: a stylet that widens to form the main pumping chamber and two sharp-tipped lancets that slide back and forth, piercing the tissue and pumping venom into the target. But the precise mechanism by which the pumping action is achieved has never been directly observed.

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Last month we covered the winner of Nikon's Small World in Motion video: Ning Xu of Tsinghua University in China, whose video captured tiny cilia beating in the airways of a child with a rare respiratory disorder. But allegations surfaced about Xu's use of AI while making the video. Nikon launched an investigation and concluded that Xu's entry did not comply with competition rules. The new winner is Nguyen Nam Nhat of Vietnam with a video of a tiny roundworm and a single-celled organism (above).

Founded in 2011, the Nikon Small World in Motion competition is a spinoff of the company’s Small World Photomicrography Competition, which has been around since 1974. Both are meant “to showcase the beauty and complexity of things seen through the light microscope”—one through still photographs, the other through photovideography, taking advantage of all the technological advances that now allow users to make movies or time-lapse images through the microscope.

The other winners also moved up a notch with Xu's disqualification. Benedikt Pleyer of Bavaria, Germany, placed second with a video of jellyfish larvae suspended in water droplets; Andrew Moore of Howard Hughes Medical Institute in the US placed third with a video of synchronized cell division in neighboring cells; Patrick Hickey of Hypha Research Ltd. in Edinburgh, Scotland, placed fourth with a video of the dynamics of mitochondria and chloroplasts in Turtle Vine leaf cells; and Igor Adameyko placed fifth with a video of a tiny, colorful sea slug (Cyerce kikutarobabai) on the move.

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Margaret Hamilton, who coined the term "software engineering" and led the development of onboard flight software for NASA's Apollo program in the 1960s, died last week at the age of 90. A recipient of the Presidential Medal of Freedom in 2016, Hamilton was also immortalized as a LEGO minifig the following year—part of the "Women of NASA" set that also included astronauts Mae Jemison and Sally Ride.

“To say Margaret Hamilton was a pioneer—to say she was ahead of her time—would be a dramatic understatement. She was a software engineer at a time when that field was in its infancy, and she not only developed advanced code herself but also led a team in using that nascent technology to develop one of the most complex systems humanity had ever achieved,” said Olivier de Weck, interim head of the MIT Department of Aeronautics and Astronautics. “The Apollo program still stands as one of our greatest testaments to the power of collaboration, ingenuity, and engineering, and Hamilton was a fundamental contributor to that program’s success.”

Born in 1936 in Paoli, Indiana, Hamilton graduated from Earlham College in 1958 with a degree in mathematics and a minor in philosophy—the latter a nod to her father (a poet) and grandfather (a headmaster). She married her first husband, James Cox Hamilton, that same year. The plan was for her to work until he finished his law degree, after which he would support her through graduate school to earn a PhD in mathematics.

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The Vesuvius Challenge is an ongoing project that combines "digital unwrapping" with crowdsourced machine learning to decipher the so-called Herculaneum scrolls, badly charred 2,000-year-old papyri too fragile to be physically unrolled. The effort just got an additional boost. A team of researchers created their own contemporary model papyrus scrolls—charring them just like the originals—to validate a screening method to determine which of the Herculaneum scrolls were written in lead-based ink and hence are the most promising candidates for further analysis. They described the process in a new paper published in the journal PLoS ONE.

As previously reported, the ancient Roman resort town of Pompeii wasn’t the only city destroyed in the catastrophic 79 AD eruption of Mount Vesuvius. Several other cities in the area, including the wealthy enclave of Herculaneum, were fried by clouds of hot gas, called pyroclastic pulses and flows. But still, some remnants of Roman wealth survived. One palatial residence in Herculaneum—believed to have once belonged to a man named Piso—contained hundreds of priceless written scrolls made from papyrus, singed into carbon by volcanic gas.

The scrolls stayed buried under volcanic mud until they were excavated in the 1700s from a single room that archaeologists believe held the personal working library of an Epicurean philosopher named Philodemus. The few opened fragments helped scholars identify various Greek philosophical texts, including On Nature by Epicurus and several by Philodemus himself, as well as a handful of Latin works. But the more than 600 rolled-up scrolls were so fragile that it was long believed they would never be readable, since even touching them could cause them to crumble.

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Chimpanzees are known to use rudimentary tools when foraging for food. According to a new paper in the journal Frontiers in Psychology, this learned behavior is passed down from adults to offspring through social learning. Specifically, adult chimps deliberately model the behavior, then turn their tools over to the youngsters so they can mimic the same motions.

"Receiving food and tools from experienced individuals, which we call food or tool transfer, may help chimpanzees learn to use technology to extract foods that are difficult to access,” said co-author Andreu Sánchez-Megías, a graduate student at the University of Barcelona and the Jane Goodall Institute Spain in Senegal. “Tool transfers thus appear to be a form of teaching, together with observation and supervised practice. It appears that mothers are the main models and teachers for young chimpanzees in this manner.”

As we have previously reported, tool use was once thought to be one of the defining features of humans, although Charles Darwin observed chimpanzees using stones to crack nuts in 1871. In 1960, the late primatologist Jane Goodall observed a chimp named David Greybeard bend a twig, strip off the leaves, and use it to spoon termites out of a nest and into his mouth. When he learned of the behavior, Goodall's mentor, Louis Leakey, famously observed, “Now we must redefine ‘tool,’ redefine ‘man,’ or accept chimpanzees as humans.” Since then, chimps have been observed making sponges out of leaves to soak up liquids, shaping sticks to collect algae, and sharpening rudimentary spears for hunting.

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Stonehenge is the most famous example of megalithic architecture across Britain and Ireland, but there are plenty of others, including Calanais, Newgrange, and Avebury, as well as the Devil's Arrows. The latter is Britain's tallest standing stone alignment, yet little is known about the provenance of its stones. Scientists have confirmed that the stones came from a site 18 kilometers (11 miles) away, transported by humans rather than glacial movement, according to a paper published in the Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences.

"Sites in southern England and Scotland receive considerable attention but monuments like the Devil's Arrows have remained comparatively understudied despite their significance," said co-author Jim Leary of the University of York. "We have now proved that Neolithic communities moved several 25-ton stones across Yorkshire, transforming a familiar site into an epic quest to create a sacred landscape."

Stonehenge has been the focus of recent chemical analyses identifying where all the stones that make up the structure came from, revealing that many originated in quarries a significant distance away. For instance, a 2019 study concluded that the 42 bluestones that make up the inner ring came all the way from western Wales. The outer layer of sarsen stones hails from much closer to home: Marlborough Downs, an area of round, grassy hills 25 to 30 km (17 miles) north of Stonehenge, which has the largest concentration of sarsen in the UK.

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The precise composition of ancient Egyptian paints, binders, adhesives, and similar materials used to make artifacts is largely unknown, in part because a full analysis would require taking samples that would damage those valuable artifacts. The development of cutting-edge, non-destructive techniques has been helping to unlock those secrets, aiding conservation efforts.

Most recently, researchers have used mass spectrometry-based proteomics to analyze the glues and adhesives in a broad set of Egyptian artifacts, according to a new paper published in the journal Science Advances. They found plenty of expected sources, such as animal collagens and egg proteins, but also plant proteins, specifically from sesame and drumstick tree (moringa) cereals.

As previously reported, the ancient Egyptians had a highly formalized (and easily recognizable) painting style, and there has been considerable interest in gaining insights into the specific pigments and painting techniques employed. Common pigments included hematite and realgar for red; goethite and orpiment for yellow; Egyptian blue; Egyptian green; carbon-based black; and calcite, gypsum, anhydrite, and huntite for white. (Just last year, Washington State University researchers were able to re-create Egyptian blue by mixing together silicon dioxide, copper, calcium, and sodium carbonate in varying proportions and heating them at very high temperatures akin to those of ancient kilns.)

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Scientists have an indisputable playful side, evidenced by frequent allusions to popular culture in their research publications. That includes popular song lyrics. And the most popular musical group, in terms of how frequently their songs and lyrics appear in the scientific literature, is The Beatles, according to a new paper published in the journal PLoS ONE.

“Some of these are genuinely brilliant," said co-author Gabriel Budel of Delft University of Technology in the Netherlands of the more than 3,000 references they found to The Beatles. "'The lung and winding road' is a paper on Long COVID that changes one vowel. 'Here comes the SU(N)' turns 'Here Comes the Sun' into a quantum computing paper about mathematical groups. Someone was having a very good day at their desk.”

Back in 2014, scientists at the Karolinska Institute in Sweden revealed that they had been deliberately inserting Bob Dylan lyrics into their papers as part of a long-running bet, starting with a 1997 Nature review entitled "Nitric Oxide and inflammation: The answer is blowing in the wind." That resulted in a 2015 study on whether Dylan lyrics appeared elsewhere in the biomedical literature; the most frequently referenced were "The Times They Are A'Changin'" and "Blowing in the Wind."

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In 2007, a piece of space debris punched a bullet-like hole through the radiator panel of the US space shuttle Endeavor. The shuttle program ended in 2011, but the space debris problem has only intensified as we launch more and more satellite constellations, telescopes, and spacecraft into orbit. That's why Chinese scientists have devised a new aluminum material inspired by eggshells that they believe could offer enhanced protection against debris fragments, according to a new paper published in the Journal of Applied Physics.

Eggshells have long fascinated scientists because of their mechanical properties. For instance, it's well known that cracking an egg requires applying just enough force to the center to achieve a clean break without completely shattering the shell. In 2012, MIT mechanical engineer Pedro Reis co-authored a paper demonstrating the link between an egg's ovoid geometry and its rigidity, a major factor when predicting how much force an object can endure before cracking. (As I wrote for Slate at the time, rigidity is related to, but distinct from, strength. If one eggshell has tiny cracks and the other doesn't, both shells have different strengths—the cracked one will break more easily—but the same rigidity.)

Reis started studying eggshells after participating in a popular physics demonstration: walking on cartons of eggs without breaking them. The key, he learned, was to align the eggs with their narrow tip (the most crack-resistant part) pointing up, and then carefully place one's feet to distribute one's weight over the entire surface area. This ensures that no single egg is overloaded. While it takes around 5.5 pounds of force to crack an egg, that depends on the direction in which the force is applied, as well as its distribution over the shell's surface.

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Sheeppox is a highly contagious, often fatal viral disease that was largely eradicated from much of European livestock in the 20th century. But there is still the occasional regional outbreak, such as the one that afflicted many flocks of sheep in Greece last year. In order to reconstruct how the virus has evolved over the last 3,500 years, scientists extracted and sequenced sheeppox DNA preserved in the animal skins used for the parchment of numerous medieval manuscripts. They reported their findings in a new paper published in the journal Science Advances.

“The recording of ancient DNA of pathogens has completely changed our understanding of infectious disease in the past, and here we show that parchment can also preserve animal pathogen DNA. It is possible that archives and libraries around the world also contain the genetic traces of disease outbreaks in animals in the past,” said co-author Louis L’Hôte, a graduate student at University College Dublin. “These genomes help us understand how these pathogens evolved and how they impacted past societies—such as sheeppox virus, which we show has been affecting Eurasian sheep herds for at least three and a half millennia.”

Per the authors, the earliest known written evidence of sheeppox infection dates to the first century CE, when Roman accounts described outbreaks of skin lesions ("pustules") in the animals. There are more frequent mentions of deadly outbreaks of "pockes" or "variola" in sheep by the Middle Ages, recorded in various agricultural texts and accounting documents in France, Spain, and England. There seemed to be a decline in outbreaks in 17th-century France, although frequent outbreaks re-emerged in the 18th and 19th centuries, often with high mortality rates in the flocks. Great Britain did not experience a sheeppox resurgence until 1847.

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It's that time of year again, when we learn which lucky scientists are among the winners of the Ig Nobel Prizes. This year, the prizes honor research on designing the perfect splash-free urinal; using mosquito proboscises to "necroprint" tiny nozzles; studying composition rates of buried cotton underwear; and the aerodynamics of a healthy nose-blow, among other highlights.

Established in 1991, the Ig Nobels are a good-natured parody of the Nobel Prizes; they honor “achievements that first make people laugh and then make them think.” The unapologetically campy awards ceremony features miniature operas, scientific demos, and "24/7 lectures," whereby experts must explain their work twice: once in 24 seconds and the second in just seven words.

Acceptance speeches are limited to 60 seconds. And as the motto implies, the research being honored might seem ridiculous at first glance, but that doesn’t mean it’s devoid of scientific merit. In the weeks following the ceremony, the winners will also give free public talks, which will be posted on the Improbable Research website.

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It’s a regrettable reality that there is never enough time to cover all the interesting scientific stories we come across. So every month, we highlight a handful of the best stories that nearly slipped through the cracks. August’s list includes the discovery of a new celestial object astronomers have dubbed a "black hole star"; breaking down plastics with microbes and turning them into edible cookies; how whale calls are connected to Einstein's special theory of relativity; and how avocado tree flowers switch sex during the day, among other highlights.

Discovery of a "black hole star"

Credit: Rohan Naidu (University of Hawai'i)

In 2024, astronomers combing through datasets taken by the James Webb Space Telescope noticed hundreds of mysterious little red dots lurking therein, believed to be baby quasars. They existed when the Universe was just a few hundred million years old. One such object in particular captured scientists' interest: a red dot that was extremely red and very bright, but whose properties didn't fit with any known astrophysical object. Astronomers have now concluded that the little red dot is a "black hole star," so named because it is the size of a large star but produces far more energy than would be possible via nuclear fusion—energy comparable to what an active black hole would produce.

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A thousand people voluntarily buried their cotton underpants for two months—not to keep the Underpants Gnomes from stealing them, but as part of a citizen science project to map out soil health in 25 countries around the world. The results of this unique experiment were reported in a new paper published in the journal Plants People Planet.

“Our results show that how soil is managed can significantly affect both soil life and soil quality,” said co-author Marcel van der Heijden, an agroecologist at the University of Zurich. “Healthy, biologically active soil is crucial for fertility, nutrient cycling and many other ecosystem services.”

Soil health is critical for agriculture and, by extension, food security, not to mention a healthy global ecosystem, but it has been declining worldwide, per the authors. One key indicator of soil health is decomposition rates of complex organic matter, breaking down stuff like leaves, wood, even cadavers into simpler organic and inorganic compounds, releasing C0₂ and nutrients in the process. There have been relatively few large-scale national decomposition studies involving different land use types, although smaller studies have shown that how humans use a site can significantly affect the soil's biological diversity.

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Fashionistas of a certain age no doubt remember the late designer Stephen Sprouse, who gave Blondie's Debbie Harry her distinctive Bowery punk style. Sprouse's first collections in the mid-1980s made a major splash, melding graffiti prints, a playful '60s aesthetic, and bright Day-Glo colors that won admirers such as Andy Warhol.

Several examples of Sprouse's work are preserved in the textiles collection of the Indianapolis Museum of Art at Newfields, where conservationists are trying to learn more about the phosphorescent and fluorescent pigments the designer used in his creations in order to keep the colors from dulling over time. They described recent advances in that research at a meeting of the American Chemical Society (ACS) held this week in Chicago.

Scientists began describing minerals that glowed in the dark as phosphors in the Middle Ages. Typically, such materials take on a charge when exposed to light, storing the absorbed energy and releasing it gradually as re-emitted light. Henri Becquerel discovered radioactive decay in 1896 because of his work with phosphorescent uranium salts: He left the salts in a closed drawer with photographic plates, which fogged up even without a light source. DayGlo paints and similar materials exploit the related phenomenon of fluorescence. DayGlo pigments fluoresce in daylight by essentially converting UV light into visible light to produce brighter, more vibrant colors.

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Any dog owner would tell you that their canine companions are attuned to their humans' emotional state and respond accordingly. Scientists have performed fMRI scans on dogs and identified a specific brain region that processes happy human facial expresses, like a smile, according to a new paper published in the journal iScience. They also found that dogs can tell the difference between negative facial expressions, specifically anger, sadness, and fear.

“Humans are really good at picking up small details on the face, and so are dogs,” said co-author Raúl Hernández-Pérez of the University of Vienna. “This makes dogs very interesting. By studying their brains, we can understand what adaptations have developed to support their remarkable social and emotional understanding of humans.”

Prior behavioral studies have shown that dogs are sensitive to emotion in human faces. Dogs will, for example, choose a box their human has identified with a happy expression over one the human treats with fear or disgust. Past fMRI studies found that an area in the canine left temporal cortex showed a stronger response to human faces compared to dog faces, as well as a greater response in the caudate, hippocampus, and amygdala to human faces showing emotion versus neutral faces.

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Snails are well-known for their mucus. The slime is highly valued as an anti-inflammatory and anti-aging ingredient in certain skin care products, and snails can secrete different kinds of mucus with properties tailored to specific functions. A team of German scientists has determined a recipe for how snails achieve that so-called tunability: Collagen and calcium work in tandem to achieve the varying mechanical properties, according to a new paper in the journal Science.

Snail mucus is mostly water; it's the mucins (glycoproteins) and complex carbohydrates that give it that slimy, viscous texture. In addition to cosmetics, the mucus holds great potential for drug delivery. In 2020, scientists found that combining snail slime from a common garden snail with gold nanoparticles helped accelerate wound healing and exhibited anti-inflammatory properties in mice. Most relevant to this latest paper is a 2023 study on garden snail slime that identified three distinct types of secreted mucus: a hydrating version to protect its skin, one that acts as an adhesive glue, and a third that serves as a lubricant so the snail can more easily glide across a surface.

The team focused their research efforts on the grove snail/lemon snail (Cepaea nemoralis), which they deemed well-suited as subjects because the snails secrete five different kinds of mucus with distinct functions. As with the garden snails, there is one that acts as a lubricant to help with locomotion and an adhesive mucus to help the snail stick to various surfaces. Then there's a mucus layer known as the epiphragm that the snail secretes when it hibernates in winter, which contains calcite and effectively seals the shell to protect the snail from predators and harsh environmental conditions.

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The parasitic fungi in the Cordyceps genus are a favorite subject of nature documentaries. They've also infiltrated popular culture via the zombie-apocalypse video game The Last of Us (2013) and its TV adaptation, in which a parasitic fungus mutates to infect humans. Scientists are keen to study Cordyceps to learn more about the origins and intricate mechanisms underlying these pathogen-based diseases.

The latest finding: DNA analysis revealed the same fungus in both parasitized insects and surrounding mosses, according to a paper published in the journal IMA Fungus. (Yes, really.) This suggests a second life stage during which the fungus lives inside the moss, possibly an evolutionary adaptation to survive when insect hosts may be scarce. It could also explain why the host species seems to prefer biting into mosses during their final death throes.

As we've previously reported, there are more than 400 different species of Cordyceps fungi, each targeting a particular insect species, like ants, dragonflies, cockroaches, aphids, or beetles. The spores attach to the target insect, such as a carpenter ant, and germinate, spreading through the host’s body via long tendrils called mycelia. Cordyceps essentially turns its host into a zombie slave, compelling the ant to climb to the top of the nearest plant and clamp its tiny jaws in a death grip around a leaf or twig.

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It’s a regrettable reality that there is never enough time to cover all the interesting scientific stories we come across. So every month, we highlight a handful of the best stories that nearly slipped through the cracks. July’s list includes outfitting cyborg cockroaches with a tiny diving suit for navigating flooded terrain; confirmation that a Medici duke died of malaria, not poisoning; the best evidence to date that Betelgeuse is orbited by a companion star; and evidence that some ancient Egyptian princesses were skilled archers.

Sacrificial Incan boy died of blunt force trauma

Credit: Administrative Archive, Regional Museum of Iquique–CORMUDESI

It's known that the Incas practiced a human sacrifice ritual known as Capachoca, in which children were offered to the mountains and believed to become divine themselves, serving as intermediaries with the gods. This often involved pilgrimages to the remote sacrificial sites, with colonial accounts describing strangulation, asphyxiation, and blunt force trauma as the most common methods of sacrifice. Archaeologists have reanalyzed the remains of one such victim and concluded the boy died from blunt force trauma, rather than freezing to death as previously believed. They described their findings in a paper published in the journal Science Advances.

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Some 66 million years ago, an asteroid impact wiped out three-quarters of all plant and animal species on Earth, most notably taking down the dinosaurs. But exactly how that impact caused those extinctions has been the subject of fierce debate. According to a new paper published in the Journal of Geophysical Research: Biogeosciences, the impact would have produced an immense cloud of dust that superheated the upper atmosphere, charbroiling living organisms unable to take shelter and igniting widespread wildfires.

As previously reported, the most widely accepted explanation for what triggered that catastrophic mass extinction is known as the “Alvarez hypothesis,” after the late physicist Luis Alvarez and his geologist son, Walter. In 1980, they proposed that the extinction event may have been caused by a massive asteroid or comet hitting the Earth. They based this conclusion on their analysis of sedimentary layers at the Cretaceous-Paleogene boundary(the K-Pg boundary, formerly known as the K-T boundary) found all over the world, which included unusually high concentrations of iridium—a metal more commonly found in asteroids than on Earth. (That same year, Dutch geophysicist Jan Smit independently arrived at a similar conclusion.)

Since then, scientists have identified a likely impact site: a large crater in Chicxulub, Mexico, in the Yucatan Peninsula, first discovered by geophysicists in the late 1970s. The impactor that created it was sufficiently large (between 11 and 81 kilometers, or 7 to 50 miles) to melt, shock, and eject granite from deep inside the Earth, probably causing a megatsunami and ejecting vaporized rock and sulfates into the atmosphere. It has been estimated that the impact would have released energy over a billion times higher than the atomic bombs dropped on Hiroshima and Nagasaki in 1945.

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