A bizarre gamma-ray burst breaks the rules for these cosmic eruptions

Astronomers have spotted a bright gamma-ray burst that upends previous theories of how these energetic cosmic eruptions occur.

For decades, astronomers thought that GRBs came in two flavors, long and short — that is, lasting longer than two seconds or winking out more quickly. Each type has been linked to different cosmic events. But about a year ago, two NASA space telescopes caught a short GRB in long GRB’s clothing: It lasted a long time but originated from a short GRB source.

“We had this black-and-white vision of the universe,” says astrophysicist Eleonora Troja of the Tor Vergata University of Rome. “This is the red flag that tells us, nope, it’s not. Surprise!”

This burst, called GRB 211211A, is the first that unambiguously breaks the binary, Troja and others report December 7 in five papers in Nature and Nature Astronomy.

Prior to the discovery of this burst, astronomers mostly thought that there were just two ways to produce a GRB. The collapse of a massive star just before it explodes in a supernova could make a long gamma-ray burst, lasting more than two seconds (SN: 10/28/22). Or a pair of dense stellar corpses called neutron stars could collide, merge and form a new black hole, releasing a short gamma-ray burst of two seconds or less.

But there had been some outliers. A surprisingly short GRB in 2020 seemed to come from a massive star’s implosion (SN: 8/2/21). And some long-duration GRBs dating back to 2006 lacked a supernova after the fact, raising questions about their origins.

“We always knew there was an overlap,” says astrophysicist Chryssa Kouveliotou of George Washington University in Washington, D.C., who wrote the 1993 paper that introduced the two GRB categories, but was not involved in the new work. “There were some outliers which we did not know how to interpret.”

There’s no such mystery about GRB 211211A: The burst lasted more than 50 seconds and was clearly accompanied by a kilonova, the characteristic glow of new elements being forged after a neutron star smashup.
“Although we suspected it was possible that extended emission GRBs were mergers … this is the first confirmation,” says astrophysicist Benjamin Gompertz of the University of Birmingham in England, who describes observations of the burst in Nature Astronomy. “It has the kilonova, which is the smoking gun.”

NASA’s Swift and Fermi space telescopes detected the explosion on December 11, 2021, in a galaxy about 1.1 billion light-years away. “We thought it was a run-of-the-mill long gamma-ray burst,” says astrophysicist Wen-fai Fong of Northwestern University in Evanston, Ill.
It was relatively close by, as GRBs go. So that allowed Fong’s and Troja’s research groups to independently continue closely observing the burst in great detail using telescopes on the ground, the teams report in Nature.

As the weeks wore on and no supernova appeared, the researchers grew confused. Their observations revealed that whatever had made the GRB had also emitted much more optical and infrared light than is typical for the source of a long GRB.

After ruling out other explanations, Troja and colleagues compared the burst’s aftereffects with the first kilonova ever observed in concert with ripples in spacetime called gravitational waves (SN: 10/16/17). The match was nearly perfect. “That’s when many people got convinced we were talking about a kilonova,” she says.

In retrospect, it feels obvious that it was a kilonova, Troja says. But in the moment, it felt as impossible as seeing a lion in the Arctic. “It looks like a lion, it roars like a lion, but it shouldn’t be here, so it cannot be,” she says. “That’s exactly what we felt.”

Now the question is, what happened? Typically, merging neutron stars collapse into a black hole almost immediately. The gamma rays come from material that is superheated as it falls into the black hole, but the material is scant, and the black hole gobbles it up within two seconds. So how did GRB 211211A keep its light going for almost a minute?

It’s possible that the neutron stars first merged into a single, larger neutron star, which briefly resisted the pressure to collapse into a black hole. That has implications for the fundamental physics that describes how difficult it is to crush neutrons into a black hole, Gompertz says.

Another possibility is that a neutron star collided with a small black hole, about five times the mass of the sun, instead of another neutron star. And the process of the black hole eating the neutron star took longer.

Or it could have been something else entirely: a neutron star merging with a white dwarf, astrophysicist Bing Zhang of the University of Nevada, Las Vegas and colleagues suggest in Nature. “We suggest a third type of progenitor, something very different from the previous two types,” he says.

White dwarfs are the remnants of smaller stars like the sun, and are not as dense or compact as neutron stars. A collision between a white dwarf and a neutron star could still produce a kilonova if the white dwarf is very heavy.

The resulting object could be a highly magnetized neutron star called a magnetar (SN: 12/1/20). The magnetar could have continued pumping energy into gamma rays and other wavelengths of light, extending the life of the burst, Zhang says.

Whatever its origins, GRB 211211A is a big deal for physics. “It is important because we wanted to understand, what on Earth are these events?” Kouveliotou says.

Figuring out what caused it could illuminate how heavy elements in the universe form. And some previously seen long GRBs that scientists thought were from supernovas might actually be actually from mergers.

To learn more, scientists need to find more of these binary-busting GRBs, plus observations of gravitational waves at the same time. Trejo thinks they’ll be able to get that when the Laser Interferometer Gravitational-Wave Observatory, or LIGO, comes back online in 2023.

“I hope that LIGO will produce some evidence,” Kouveliotou says. “Nature might be graceful and give us a couple of these events with gravitational wave counterparts, and maybe [help us] understand what’s going on.”

In 2022, the James Webb Space Telescope brought us new views of the cosmos

This year marked the end of a decades-long wait for astronomers. The James Webb Space Telescope is finally in action.

The telescope, which launched in December 2021, released its first science data in July (SN: 8/13/22, p. 30) and immediately began surpassing astronomers’ expectations.

“We’ve realized that James Webb is 10 times more sensitive than we predicted” for some kinds of observations, says astronomer Sasha Hinkley of the University of Exeter in England. His team released in September the telescope’s first direct image of an exoplanet (SN: 9/24/22, p. 6). He credits “the people who worked so hard to get this right, to launch something the size of a tennis court into space on a rocket and get this sensitive machinery to work perfectly. And I feel incredibly lucky to be the beneficiary of this.”
The telescope, also known as JWST, was designed to see further back into the history of the cosmos than ever before (SN: 10/9/21 & 10/23/21, p. 26). It’s bigger and more sensitive than its predecessor, the Hubble Space Telescope. And because it looks in much longer wavelengths of light, JWST can observe distant and veiled objects that were previously hidden.

JWST spent its first several months collecting “early-release” science data, observations that test the different ways the telescope can see. “It is a very, very new instrument,” says Lamiya Mowla, an astronomer at the University of Toronto. “It will take some time before we can characterize all the different observation modes of all four instruments that are on board.”

That need for testing plus the excitement has led to some confusion for astronomers in these heady early days. Data from the telescope had been in such high demand that the operators hadn’t yet calibrated all the detectors before releasing data. The JWST team is providing calibration information so researchers can properly analyze the data. “We knew calibration issues were going to happen,” Mowla says.

The raw numbers that scientists have pulled out of some of the initial images may end up being revised slightly. But the pictures themselves are real and reliable, even though it takes some artistry to translate the telescope’s infrared data into colorful visible light (SN: 3/17/18, p. 4).

The stunning photos that follow are a few of the early greatest hits from the shiny new observatory.
JWST has captured the deepest views yet of the universe (above). Galaxy cluster SMACS 0723 (bluer galaxies) is 4.6 billion light-years from Earth. It acts as a giant cosmic lens, letting JWST zoom in on thousands of even more distant galaxies that shone 13 billion years ago (the redder, more stretched galaxies). The far-off galaxies look different in the mid-infrared light (above left) captured by the telescope’s MIRI instrument than they do in the near-infrared light (above right) captured by NIRCam. The first tracks dust; the second, starlight. Early galaxies have stars but very little dust.
JWST was built to peer over vast cosmic distances, but it also provides new glimpses at our solar system neighbors. This pic of Neptune was the first close look at its delicate-looking rings in over 30 years (SN: 11/5/22, p. 5).
The rings in this astonishing image are not an optical illusion. They’re made of dust, and a new ring is added every eight years when the two stars in the center of the image come close to each other. One of the stars is a Wolf-Rayet star, which is in the final stages of its life and puffing out dust. The cyclical dusty eruptions allowed scientists to directly measure for the first time how pressure from starlight pushes dust around (SN: 11/19/22, p. 6).
With JWST’s unprecedented sensitivity, astronomers plan to compare the earliest galaxies with more modern galaxies to figure out how galaxies grow and evolve. This galactic smashup, whose main remnant is known as the Cartwheel galaxy, shows a step in that epic process (SN Online: 8/3/22). The large central galaxy (right in the above composite) has been pierced through the middle by a smaller one that fled the scene (not in view). The Hubble Space Telescope previously snapped a visible light image of the scene (top half). But with its infrared eyes, JWST has revealed much more structure and complexity in the galaxy’s interior (bottom half).
The gas giant HIP 65426b was the first exoplanet to have its portrait taken by JWST (each inset shows the planet in a different wavelength of light; the star symbol shows the location of the planet’s parent star). This image, released by astronomer Sasha Hinkley and colleagues, doesn’t look like much compared with some of the other spectacular space vistas from JWST. But it will give clues to what the planet’s atmosphere is made of and shows the telescope’s potential for doing more of this sort of work on even smaller, rocky exoplanets (SN: 9/24/22, p. 6).
Another classic Hubble image updated by JWST is the Pillars of Creation. When Hubble viewed this star-forming region in visible light, it was shrouded by dust (above left). JWST’s infrared vision reveals sparkling newborn stars (above right).

The ancestor to modern brewing yeast has been found hiding in Ireland

In 1516, the duchy of Bavaria in Germany imposed a law on its beer brewers meant to reserve ingredients like wheat and rye for the baking of bread. The decree restricted brewers to using only barley, hops, water and yeast to make their libations, and set the prices for beer depending on the time of year. The law inadvertently limited brewing to the winter, which favored a cold-tolerant yeast called Saccharomyces pastorianus, which brews lager, over the more common S. cerevisiae, which brews ale.

S. pastorianus is a hybrid, produced from the mating of S. cerevisiae with another yeast called S. eubayanus. Despite lager’s European origins, S. eubayanus hadn’t actually been found there and was only first discovered in 2011, in the Patagonia region of South America (SN: 8/23/11). Now, thanks to a research project carried out by undergraduate students, S. eubayanus has been found living in European soil — fittingly, in the beer-loving nation of Ireland.

“Since the discovery of S. eubayanus [more than] 10 years ago, it’s been a fun puzzle putting together where the species is actually found,” says Quinn Langdon, a biologist at Stanford University, who was not involved with the study.

A leading theory is that S. eubayanus originated in Patagonia and then spread around the world, eventually mating with S. cerevisiae in European breweries to make S. pastorianus.

Geraldine Butler, a geneticist at University College Dublin and leader of the project, always thought that teaching genome-sequencing techniques by having students scour soils for yeast could turn up S. eubayanus. Still, she says, she couldn’t contain her excitement when she saw the first hint of the microbe. “I was sitting by the sequencer waiting for the results to come out,” she says.

One of Butler’s students, Stephen Allen, found two local strains of S. eubayanus hiding in plain sight on the Belfield campus of University College Dublin. The team has since gone back and found the yeast again, Butler says, suggesting that there is a stable population of the yeast living in the Irish soil.

The new discovery was published December 7 in FEMS Yeast Research.

Butler hopes this discovery will brew interest elsewhere in Europe to search for S. eubayanus, including in Bavaria, where lager brewing is thought to have first started. She is also looking for commercial partners to try making beer with the Irish strains.

Langdon isn’t confident that the new microbes will lead to tasty brews because there are other S. eubayanus strains that don’t grow well on maltose, the sugar that needs to be digested by yeasts during the brewing process. Still, Langdon says, “it’d be fun to brew with them.”
Whether the newly discovered Irish strains of S. pastorianus’ missing parent taste good or not, there’s no denying that their discovery helps solve a little piece of the puzzle of lager brewing’s origins. That 16th century shift from S. cerevisiae to S. pastorianus led to a global shift that continues to this day — more than 90 percent of beer sold worldwide today is lager.

Fungi are the “forgotten kingdom,” Langdon says, not getting as much attention as plants or animals, despite playing an outsize role in human history. “Yeasts are just single cells living in the soil, and they’re doing really important things.”

Tina Lasisi wants to untangle the evolution of human hair

Though humans’ nearly hairless bodies stick out like a cowlick among other primates, our nakedness isn’t unique in the world of mammals. Dolphins and whales are naked, says biological anthropologist Tina Lasisi of the University of Southern California in Los Angeles. There are naked mole-rats. “Elephants, depending on how you look at them, are kind of naked,” she says. “But we’re the only weirdos that are naked except for our head.”

Our species traded off much of our body hair for more sweat glands, an evolutionary adaptation that helps us regulate body heat more efficiently. But what about another uniquely human feature? We’re the only animals known to express tightly curled hair, like that seen in many people of African descent. Lasisi wants to know why and how it came to be.

For decades, traits that have been associated with racial categories, such as skin pigmentation and hair texture, have gone understudied or ignored among anthropologists, Lasisi says. Much of the study of human biological variation was deserted after the post–World War II backlash against eugenics, a racist field birthed from the idea that humankind could be improved if those deemed to have desirable traits were selectively allowed to reproduce. Since then, research on human variation has largely focused instead on traits that are not overtly racialized, such as lactose intolerance and adaptations to high altitudes.

But studying all forms of human variation is crucial to understanding our species’s evolution, Lasisi says. Studying variation in a way that normalizes rather than dampens or paints differences in a bad light is key not only to righting anthropology’s harmful legacy, but also ethical, socially responsible and sound science, she says.
Lasisi discovered biological anthropology as an undergraduate student at the University of Cambridge. As a Black person who spent many of her formative years among white people in the Netherlands, she was always aware of skin color. She vividly remembers learning that human skin pigmentation evolved as an adaptation to ultraviolet radiation — research pioneered by anthropologist Nina Jablonski of Penn State, who would later become Lasisi’s primary adviser. “It’s like a lightbulb went off in my head,” Lasisi says, and it made her wonder, “What else out there can be explained by evolution?”

Her interest in the origins of curly hair grew in part as an effort to understand her own locks. “Research is me-search,” Lasisi says. But when she first began, there wasn’t much science to comb through, and methodologies for measuring hair texture were either unreliable or inefficient.
Standout research
As part of her Ph.D. research, Lasisi worked with a team of anthropologists, thermal engineers and physiologists to study how curly hair might have given our bipedal ancestors a leg up in the hot and dry African savanna.

The team placed a variety of wigs made of human hair onto heat-sensing models and measured heat transfer in different environments. In dry settings, curly hair, especially tightly curled hair, protected the scalp from solar radiation while releasing more heat from the head than straight hair. Lasisi speculates that the larger amount of air space within curly hair is what does the trick.

To underpin her efforts and support future hair research, Lasisi developed an improved and standardized way of measuring hair curvature and cross-sectional shape. The technique involves segmenting, washing and taking pictures of hair strands and then running the images through an open-source computer program that she created.

Measuring these characteristics on a continuous spectrum (much like we do height, for instance), she argues, is a better way of studying hair texture than the long-standing practice of classifying hair into discrete categories, such as straight, wavy or curly. Such discrete categories are not standardized among experts and can become subjective, she says. They also obscure the immense variation that exists, even on a single person’s head, and especially among curly hair.
Lasisi is doing highly technical work that hasn’t been part of the conversation, says Robin Nelson, a biological anthropologist at Arizona State University in Tempe. “Before Tina, very few people were working on hair texture in the same way.”

Lasisi will bring this experience to the University of Michigan in Ann Arbor as an assistant professor in 2023, where she’ll continue her studies on human variation.

Reaching out
Lasisi wants everyone to be included in conversations about what makes humans human. She has appeared on the podcast Getting Curious with Jonathan Van Ness (of Queer Eye fame). She also hosts a PBS digital show on human evolutionary biology called Why Am I Like This?, which she helps conceptualize and write.

What’s more, Lasisi has cultivated a community of curious science seekers on Twitter, Instagram and TikTok. Through short-form videos marked by her signature wit and humor, such as her “Melanin March” series or “Darwin’s greatest hits against white supremacy,” Lasisi educates thousands of followers on human variation, how to talk about race and ethnicity from an anthropological perspective, and much more. She even gives prospective anthropologists career tips and behind-the-scenes glimpses of life in academia. Two-way discussions let her learn from her audience, which she calls her “little focus groups.”
Lasisi hopes her research and outreach will inspire and provide a helpful framework for more nuanced discussions about race, ethnicity, ancestry and human diversity — and that her visibility as a Black anthropologist will encourage other people of color to ask questions that are important to them. “I want to put enough information out there in the world, and [have] enough people out there in the world who have a grasp of that information,” she says, “so that we can see human variation for the beautiful, magnificent, complex thing that it is.”

The pandemic may be stunting young adults’ personality development

The psychological development of young adults may have taken a hit, thanks to the COVID-19 pandemic.

In typical times, people tend to become more conscientious and agreeable and less neurotic with age, a process known as psychological maturation. But in the United States, the pandemic seems to have reversed that personality trajectory, especially among adults under 30, researchers report September 28 in PLOS ONE. If those patterns persist, that could spell long-term trouble for this cohort, the researchers say.

“You get better as you go through life at being responsible, at coping with emotions and getting along with others,” says personality psychologist Rodica Damian of the University of Houston, who was not involved with this study. “The fact that in these young adults you see the opposite pattern does show stunted development.”
Personalities shape how people think, feel and behave. Researchers often assess a person’s personality profile along five core traits: neuroticism, conscientiousness, agreeableness, extraversion and openness to experience (SN: 9/1/21). Over time, these traits change slightly in individuals; neuroticism tends to decrease, for example, while agreeableness typically improves.

The pandemic, though, may be upending those typical trend lines. Even after factoring out expected changes, researchers in the new study observed about a decade’s worth of personality change, averaged across all study participants, in just three years — but going in the opposite of the expected direction. Young adults showed the greatest change in certain traits. Middle-aged adults — 30 to 64 years old — showed more change across all traits. The personalities of older adults, meanwhile, stayed largely unchanged.

Such age differences make intuitive sense to personality psychologist Wiebke Bleidorn of the University of Zurich. “The density of experiences in adolescence and young adulthood is so much higher” than in later life, says Bleidorn, who was not involved with the study. “If you miss out on your senior year of high school, you can’t get that back.”
To look at personality change in the United States before and during the pandemic, personality psychologist Angelina Sutin and colleagues analyzed data from the Understanding America Study.
This survey looks at how attitudes and behaviors in the country change in response to major events, such as the 2020 presidential election and the ongoing pandemic. Among those surveyed, roughly 7,000 people — ranging in age from 18 to 109 — took a personality inventory at least once in the six years prior to the pandemic and once during the pandemic.

Based on those responses, neuroticism overall in the United States dropped slightly in 2020, during the first year of the pandemic. That finding mirrors what the researchers found with a different dataset two years ago, when they reported that neuroticism declined in adults during the first six weeks of the pandemic. But the new findings include data from 2021 and 2022, which show that the dip was fleeting.

That initial dip was probably due to the sense of solidarity that emerged in the health crisis’s earlier months, along with people attributing their worries to the crisis rather than their own internal state, says Sutin, of Florida State University in Tallahassee. “In the second year, all that support fell apart.”
Average neuroticism scores have since rebounded to pre-pandemic levels. But the picture is nuanced, the researchers found. The 2020 dip was driven almost entirely by middle-aged participants and older adults. For those two groups, neuroticism scores continued to fall over the following years, albeit more slowly than before the pandemic. Neuroticism scores among young adults in 2021 and beyond, however, surpassed pre-pandemic levels.

Similarly, conscientiousness and agreeableness scores also declined among middle-aged adults in 2021 and early 2022, but the drop wasn’t nearly as steep as the one observed among young adults.

The findings are troubling, Sutin says. “We know these traits predict all sorts of long-term outcomes.”

For instance, high neuroticism links to mental health issues, such as anxiety, depression and feelings of loneliness. And low conscientiousness is linked to poor educational, work, health and relationship outcomes.

Still, whether these personality changes persist remains to be seen. It could be that young adults “missed the train” during a critical development period, Damian says. Maybe they would have gotten a college degree or pursued a more lucrative career without the pandemic. Or maybe these people can still reach their designated stop, just behind schedule.

“There are critical developmental periods and then there is plasticity,” Damian says. “We don’t know how it’s going to play out.”

NASA’s DART spacecraft just smashed into an asteroid — on purpose

Mission control rooms rarely celebrate crash landings. But the collision of NASA’s DART spacecraft with an asteroid was a smashing success.

At about 7:15 p.m. EDT on September 26, the spacecraft hurtled into Dimorphos, an asteroid moonlet orbiting a larger space rock named Didymos. The mission’s goal was to bump Dimorphos slightly closer to its parent asteroid, shortening its 12-hour orbit around Didymos by several minutes.

The Double Asteroid Redirection Test, or DART, is the world’s first attempt to change an asteroid’s motion by ramming a space probe into it (SN: 6/30/20). Neither Dimorphos nor Didymos poses a threat to Earth. But seeing how well DART’s maneuver worked will reveal how easy it is to tamper with an asteroid’s trajectory — a strategy that could protect the planet if a large asteroid is ever discovered on a collision course with Earth.

“We don’t know of any large asteroids that would be considered a threat to Earth that are coming any time in the next century,” says DART team member Angela Stickle, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. “The reason that we are doing something like DART is because there are asteroids that we haven’t discovered yet.”
Astronomers have spotted almost all the kilometer-size asteroids in the solar system that could end civilization if they hit Earth, says Jessica Sunshine, a planetary scientist at the University of Maryland in College Park who’s also on the DART team. But when it comes to space rocks around 150 meters wide, like Dimorphos, “we only know where about 40 percent of those are,” Sunshine says. “And that is something that, if it did hit, would certainly take out a city.”

Dimorphos is a safe asteroid to give an experimental nudge, says Mark Boslough, a physicist at Los Alamos National Laboratory in New Mexico who has studied planetary protection but is not involved in DART. “It’s not on a collision course” with Earth, he says, and DART “can’t hit it hard enough to put it on a collision course.” The DART spacecraft weighs only as much as a couple of vending machines, whereas Dimorphos is thought to be nearly as hefty as Egypt’s Great Pyramid of Giza.

After a 10-month voyage, DART met up with Didymos and Dimorphos near their closest approach to Earth, about 11 million kilometers away. Up until the very end of its journey, DART could see only the larger asteroid, Didymos. But about an hour before impact, DART spotted Dimorphos in its field of view. Using its onboard camera, the spacecraft steered itself toward the asteroid moonlet and slammed into it at some 6.1 kilometers per second, or nearly 14,000 miles per hour.
DART’s camera feed went dark after impact. But another probe nearby is expected to have caught the collision on camera. The Light Italian CubeSat for Imaging of Asteroids rode to Dimorphos aboard DART but detached a couple of weeks before impact to watch the event from a safe distance. Its mission was to whiz past Dimorphos about three minutes after DART’s impact to snap pictures of the crash site and the resulting plume of asteroid debris launched into space. The probe is expected to beam images of DART’s demise back to Earth within a couple of days.

“I was absolutely elated, especially as we saw the camera getting closer and just realizing all the science that we’re going to learn,” said Pam Melroy, NASA Deputy Administrator, after the impact. “But the best part was seeing, at the end, that there was no question there was going to be an impact, and to see the team overjoyed with their success.”
DART’s impact is expected to shove Dimorphos into a closer, shorter orbit around Didymos. Telescopes on Earth can clock the timing of that orbit by watching how the amount of light from the double asteroid system changes as Dimorphos passes in front of and behind Didymos.

“It’s really a beautifully conceived experiment,” Boslough says. In the coming weeks, dozens of telescopes across every continent will watch Dimorphos to see how much DART changed its orbit. The Hubble and James Webb space telescopes may also get images.
“It’ll be really interesting to see what comes out,” says Amy Mainzer, a planetary scientist at the University of Arizona in Tucson who is not involved in DART. “Asteroids have a way of surprising us,” she says, because it’s hard to know a space rock’s precise chemical makeup and internal structure based on observations from Earth. So Dimorphos’ motion post-impact may not exactly match researchers’ expectations.

The DART team will compare data on Dimorphos’ new orbit with their computer simulations to see how close those models were to predicting the asteroid’s actual behavior and tweak them accordingly. “If we can get our models to reproduce what actually happened, then you can use those models to [plan for] other scenarios that might show up in the future” — like the discovery of a real killer asteroid, says DART team member Wendy Caldwell, a mathematician and planetary scientist at Los Alamos National Laboratory.

“No matter what happens,” she says, “we will get information that is valuable to the scientific community and to the planetary defense community.”

In Maya society, cacao use was for everyone, not just royals

In ancient Maya civilization, cacao wasn’t just for the elites.

Traces of the sacred plant show up in ceramics from all types of neighborhoods and dwellings in and around a former Maya city, researchers report September 26 in the Proceedings of the National Academy of Sciences. The finding suggests that, contrary to previous thinking, cacao was consumed at every social level of Maya society.

“Now we know that the rituals the elite depict with cacao were likely played out, like Thanksgiving, like any other ritual, by everyone,” says Anabel Ford, an archaeologist at the University of California, Santa Barbara.
Cacao — which chocolate is made from — was sacred to the ancient Maya, consumed in rituals and used as a currency. The cacao tree (Theobroma cacao) itself was linked to Hun Hunahpu, the maize god. Previous research found cacao in ceremonial vessels and elite burials, suggesting that its use was restricted to those at the top.

To explore the extent to which cacao was used in broader Maya society, Ford and colleagues examined 54 ceramic shards dating from A.D. 600 to 900 (SN: 9/27/18). The shards come from jars, mixing bowls, serving plates and vases thought to be drinking vessels. All the pieces were found in residential and ceremonial civic areas of varying size and status from city centers, foothills, upland areas and the valley around the former Maya city of El Pilar, on the present-day border of Guatemala and Belize.

To identify cacao, the researchers searched for theophylline, a compound found in trace amounts in the plant. The team found the compound on more than half of the samples, on all types of ceramics and distributed throughout social contexts.

Future research will move beyond who consumed cacao and explore the role of farmers in managing the critical resource. “A better question is to understand who grew it,” Ford says, because those people probably had greater access to the prized commodity.

A protogalaxy in the Milky Way may be our galaxy’s original nucleus

The Milky Way left its “poor old heart” in and around the constellation Sagittarius, astronomers report. New data from the Gaia spacecraft reveal the full extent of what seems to be the galaxy’s original nucleus — the ancient stellar population that the rest of the Milky Way grew around — which came together more than 12.5 billion years ago.

“People have long speculated that such a vast population [of old stars] should exist in the center of our Milky Way, and Gaia now shows that there they are,” says astronomer Hans-Walter Rix of the Max Planck Institute for Astronomy in Heidelberg, Germany.
The Milky Way’s ancient heart is a round protogalaxy that spans nearly 18,000 light-years and possesses roughly 100 million times the mass of the sun in stars, or about 0.2 percent of the Milky Way’s current stellar mass, Rix and colleagues report in a study posted September 7 at arXiv.org.

“This study really helps to firm up our understanding of this very, very, very young stage in the Milky Way’s life,” says Vasily Belokurov, an astronomer at the University of Cambridge who was not involved in the work. “Not much is really known about this period of the Milky Way’s life,” he says. “We’ve seen glimpses of this population before,” but the new study gives “a bird’s-eye view of the whole structure.”

Most stars in the Milky Way’s central region abound with metals, because the stars originated in a crowded metropolis that earlier stellar generations had enriched with those metals through supernova explosions. But Rix and his colleagues wanted to find the exceptions to the rule, stars so metal-poor they must have been born well before the rest of the galaxy’s stellar denizens came along — what Rix calls “a needle-in-a-haystack exercise.”

His team turned to data from the Gaia spacecraft, which launched in 2013 on a mission to chart the Milky Way (SN: 6/13/22). The astronomers searched about 2 million stars within a broad region around the galaxy’s center, which lies in the constellation Sagittarius, looking for stars with metal-to-hydrogen ratios no more than 3 percent of the sun’s.

The astronomers then examined how those stars move through space, retaining only the ones that don’t dart off into the vast halo of metal-poor stars engulfing the Milky Way’s disk. The end result: a sample of 18,000 ancient stars that represents the kernel around which the entire galaxy blossomed, the researchers say. By accounting for stars obscured by dust, Rix estimates that the protogalaxy is between 50 million and 200 million times as massive as the sun.

“That’s the original core,” Rix says, and it harbors the Milky Way’s oldest stars, which he says probably have ages exceeding 12.5 billion years. The protogalaxy formed when several large clumps of stars and gas conglomerated long ago, before the Milky Way’s first disk — the so-called thick disk — arose (SN: 3/23/22).

The protogalaxy is compact, which means little has disturbed it since its formation. Smaller galaxies have crashed into the Milky Way, augmenting its mass, but “we didn’t have any later mergers that deeply penetrated into the core and shook it up, because then the core would be larger now,” Rix says.

The new data on the protogalaxy even capture the Milky Way’s initial spin-up — its transition from an object that didn’t rotate into one that now does. The oldest stars in the proto–Milky Way barely revolve around the galaxy’s center but dive in and out of it instead, whereas slightly younger stars show more and more movement around the galactic center. “This is the Milky Way trying to become a disk galaxy,” says Belokurov, who saw the same spin-up in research that he and a colleague reported in July.

Today, the Milky Way is a giant galaxy that spins rapidly — each hour our solar system speeds through 900,000 kilometers of space as we race around the galaxy’s center. But the new study shows that the Milky Way got its start as a modest protogalaxy whose stars still shine today, stars that astronomers can now scrutinize for further clues to the galaxy’s birth and early evolution.

Drumming woodpeckers use similar brain regions as songbirds

Songbirds get a lot of love for their dulcet tones, but drummers may start to steal some of that spotlight.

Woodpeckers, which don’t sing but do drum on trees, have brain regions that are similar to those of songbirds, researchers report September 20 in PLOS Biology. The finding is surprising because songbirds use these regions to learn their songs at an early age, yet it’s not clear if woodpeckers learn their drum beats (SN: 9/16/21). Whether woodpeckers do or not, the result suggests a shared evolutionary origin for both singing and drumming.
The ability to learn vocalizations by listening to them, just like humans do when learning to speak, is a rare trait in the animal kingdom. Vocal learners, such as songbirds, hummingbirds and parrots, have independently evolved certain clusters of nerve cells called nuclei in their forebrains that control the ability. Animals that don’t learn vocally are thought to lack these brain features.

While it’s commonly assumed that other birds don’t have these nuclei, “there’s thousands of birds in the world,” says Matthew Fuxjager, a biologist at Brown University in Providence, R.I. “While we say these brain regions only exist in these small groups of species, nobody’s really looked in a lot of these other taxa.”

Fuxjager and his colleagues examined the noggins of several birds that don’t learn vocally to check if they really did lack these brain nuclei. Using molecular probes, the team checked the bird brains for activity of a gene called parvalbumin, a known marker of the vocal learning nuclei. Many of the birds, including penguins and flamingos, came up short, but there was one exception — male and female woodpeckers, which had three spots in their brains with high parvalbumin activity.

Though woodpeckers don’t sing, they do perform a rapid drumming on trees and house gutters to defend their territories or find mates. This drumming is different from the drilling the birds do to find food. When the team found brain nuclei similar to songbirds in woodpeckers, Fuxjager was immediately intrigued. “I thought right away it’s probably related to drumming,” he says.

The researchers subjected downy woodpeckers (Dryobates pubescens) in the wild to audio recordings of drumming from other woodpeckers. This faux territorial invasion sparked an aggressive drumming response from the birds, which were then captured and euthanized to have their recent brain activity analyzed. Sure enough, the same regions identified by earlier lab tests had been activated in the drummers.

The brains of bird vocalists and drummers evolved separately, but the similarity of the analyzed regions hints at a common origin. “It suggests that there are common themes about how you develop these complex behaviors,” says Bradley Colquitt, a biologist at the University of California, Santa Cruz who was not involved in the study. The neural circuitry formed by these nuclei most likely developed from an ancestral circuit controlling movement, Colquitt says.

“Birdsong is basically the brain controlling muscles in a vocal organ called the syrinx,” Fuxjager says. These sophisticated movements are not unlike the swift head-and-neck motions involved in drumming.

Whether drumming is learned like birdsong remains an open question that the team is now exploring. Future work will also look at how woodpeckers’ brains are wired, how these nuclei control drumming and how the brain regions’ role in drumming evolved across woodpecker species, Fuxjager says.

This new study “uncovers another species that we can add to our comparative efforts” to better understand how complex behaviors evolve, Colquitt says. “It is a preview into potentially exciting evolutionary neurobiology.” Now that woodpeckers have joined the band of important musical birds, it looks like the drummers may soon get their chance to shine.

Fossil finds put gibbons in Asia as early as 8 million years ago

Small-bodied, long-armed apes called gibbons swing rapidly through the trees, far outpacing scientists’ attempts to decipher these creatures’ evolutionary story.

Now, a partial upper jaw and seven isolated teeth found near a southwestern Chinese village have added bite to a suggestion that the earliest known gibbons hung out there about 7 million to 8 million years ago, researchers report in the October Journal of Human Evolution..

Those fossils, as well as 14 teeth previously found at the same site and a nearby site, belong to an ancient hylobatid species called Yuanmoupithecus xiaoyuan, say paleoanthropologist Xueping Ji of the Kunming Natural History Museum of Zoology in China and colleagues. Hylobatids, a family of apes that includes about 20 species of living gibbons and a black-furred gibbon called the siamang, inhabit tropical forests from northeastern India to Indonesia.
Ji’s group has presumed that Y. xiaoyuan was an ancient gibbon since introducing the species in a 2006 Chinese publication. But additional fossils were needed to check that suspicion.

The newly discovered upper jaw piece — found by a local villager and given to Ji during fieldwork around a decade ago — contains four teeth, including a partly erupted molar that helped researchers identify it as the remains of an infant that died before reaching age 2.

Comparisons with modern apes and fossils of ancient primates peg Y. xiaoyuan as the oldest known gibbon and cast doubt on a two-year-old report that a roughly 13-million-year-old molar tooth found in northern India came from a hylobatid, the team says (SN: 9/8/20). The fossil found in India, assigned to a species dubbed Kapi ragnagarensis, represents an extinct group of South Asian primates that were not closely related to present-day apes, the scientists say.

Prior DNA analyses of living primates suggested that hylobatids diverged from other apes in Africa between 22 million and 17 million years ago. But it’s a mystery when gibbon ancestors arrived in Eurasia, says paleoanthropologist and study coauthor Terry Harrison of New York University. A gap in the fossil record of about 10 million years exists between the estimated time when hylobatids emerged in or near Africa and evidence of Y. xiaoyuan in Asia.

Genetic evidence also indicates that gibbon species today shared a common ancestor around 8 million years ago, when Y. xiaoyuan was alive. “It could be that [Y. xiaoyuan] is the ancestor of all later gibbons,” Harrison says. If not, Y. xiaoyuan was closely related to a modern gibbon ancestor, he suspects.

Bumps and depressions on chewing surfaces and other tooth and jaw features of Y. xiaoyuan look much like those of living gibbons, Ji’s team says. Some traits of the fossil species were precursors of slightly different traits in modern gibbons, the researchers suggest.

Based on molar sizes, they estimate that Y. xiaoyuan weighed about six kilograms, similar to gibbons today. Molar structure indicates that Y. xiaoyuan focused on eating fruits, like most gibbon species today, Harrison says.

Ji’s group “makes a very good case that [Y. xiaoyuan] is a hylobatid,” says paleoanthropologist David Alba of Institut Català de Paleontologia Miquel Crusafont in Barcelona.

But the evolutionary status of K. ragnagarensis remains unsettled because only a single tooth from that species has been found, says Alba, who did not participate in the new study.