Thursday, September 11, 2025

Revealed: The long legacy of human-driven ant decline in Fiji

American Association for the Advancement of Science (AAAS)

Summary author: Walter Beckwith

A new study of ants in Fiji – involving genomic sequencing of over 4,000 ant specimens from museum collections – shows that most native species have been in decline since humans first arrived in the archipelago 3,000 years ago. Meanwhile, recently introduced ant species have expanded. The findings underscore how human activity has and continues to reshape fragile island ecosystems. Insects, which make up much of Earth’s biodiversity, provide crucial ecosystem services, including pollination, soil health, and natural pest control. Recent reports of dramatic declines in insect abundance and diversity – sometimes referred to as the “insect apocalypse” – have raised global concern. Although factors such as habitat destruction, agricultural intensification, climate change, pesticide use, and light pollution are frequently implicated, the scale and universality of these declines remain debated because most studies rely on relatively short-term data or historical collections spanning only decades to centuries, leaving long-term trends largely unexplored. Advances in genomic techniques now allow scientists to reconstruct historical population trends over thousands of years, however, providing insight into how both recent and ancient human activities have shaped insect communities.

Here, Cong Liu and colleagues examined long-term trends in abundance, diversity, and ecological roles of ants in the Fijian archipelago. Ants – abundant and functionally important – serve as indicators of broader biodiversity patterns, making them ideal for such studies. And islands like Fiji, with high numbers of endemic species, are especially vulnerable to human impacts. Liu et al., applied a community genomics approach, which used high-throughput genomic sequencing on over 4,000 ant specimens from Fijian museum collections, to estimate long-term community assembly and demographic trends of ants on the islands. Fiji’s ant fauna was shaped by at least 65 colonization events, they say. Some arrived millions of years ago, which led to endemic Fijian species. Regional Pacific colonizations also impacted Fiji’s ant fauna, as did more modern introductions of ant species by humans through global trade. Notably, population modeling revealed stark differences between endemic and non-endemic species. About 79% of endemic ants – mostly confined to high-elevation, intact forests – have declined, with reductions beginning after humans first settled Fiji ~3,000 years ago and accelerating in the past 300 years alongside European contact, industrial agriculture, and species introductions. In contrast, widespread Pacific species and recent human-introduced invasive ants, which are more tolerant or adapted to human-dominant habitats, have generally expanded their populations, particularly in disturbed lowland habitats. These divergent trajectories reflect how ecological traits, habitat preference, and biogeographic context determine which species “win or lose” in the Anthropocene, Liu et al. say.

For reporters interested in the novelty of the methods and collections used in this study, study coauthor Evan Economo notes; “Community genomics refers to approaches that infer patterns and processes from genomic data across many species living together (i.e. an ecological community), rather than one or a few species at a time. In this case, by analyzing many species in parallel, we were able to infer patterns of population change across the community to recover general trends. In principle, approaches like this have a lot of potential to analyze communities of any taxon, whether it is to look for evidence for declines or other ecological dynamics of interest. In this project, we recovered genomic data from museum collections, and this is an example of how such specimens are a continual source of insight as new technologies come online. Collections are not just some old stuff we store in the attic, they become more valuable over time as the information they contain is unlocked in ways that may have been unimaginable to the people who originally collected the specimens decades or centuries ago. Furthermore, we cannot fully anticipate how biodiversity collections can be used by humanity in the future, and this is why it is critical to invest in stewarding and growing collections for future generations.”

Journal

Science

DOI

10.1126/science.ads3004

Article Title

Genomic signatures indicate massive declines of endemic island insects

Article Publication Date

11-Sep-2025

Island ant communities show signs of ‘insect apocalypse’

79% of endemic species show signs of decline, highlighting the vulnerability of island biodiversity to ecosystem changes.

Okinawa Institute of Science and Technology (OIST) Graduate University

Pinned ant collection — image:
Museum collection of pinned ants from Fiji. This study involved extensive genome sampling from thousands of Fijian ant specimens, highlighting the vital importance of these museum collections as resources for biodiversity monitoring and conservation. 
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Credit: Peter Ginter

From pollinating flowers to enabling decomposition and supporting nutrient cycles, insects’ abundance and biodiversity are critical for maintaining healthy ecosystems. However, recent studies showing population declines have raised alarm about how insects are coping with the modern world. Understanding whether recent observations are part of longer timescale trends can help inform global conservation efforts, and identify the reasons behind the so-called “Insect Apocalypse”.

Published in Science, researchers from the Okinawa Institute of Science and Technology (OIST) used a community genomics approach to explore ant populations in the Fijian archipelago as a model system to understand insect biodiversity trends. By studying the genomics of museum collections, they were able to trace the ants’ evolutionary relationships to explore their arrival to the islands and reconstruct the population history of the species.

Global conservation efforts rely on biodiversity monitoring, but often focus on larger photogenic animals, and on easier to monitor areas, like temperate habitats. However, it’s widely suspected that many insect species are experiencing rapid population decline. We know that island systems are hotspots of biodiversity, so they are critical to study. Dr. Evan Economo, a Professor at OIST and the University of Maryland, and one of the senior authors on the paper, explains, “It can be difficult to estimate historical changes to insect populations, because with few exceptions, we haven’t been directly monitoring populations over time. We take a novel approach to this problem by analyzing the genomes of many species in parallel from museum specimens collected recently. The genomes hold evidence of whether populations are growing or shrinking, allowing us to reconstruct community-wide changes.”

What the researchers found is alarming; 79% of the endemic species (species found only in Fiji) are in decline, over a timescale which correlates with the arrival of humans to the islands. Meanwhile, ant species recently brought by humans are exploding in population. The largest proportion of declines are seemingly within the most recent few hundred years, coinciding with European contact, colonization, global trade and the introduction of modern agricultural techniques.

A community-wide approach

By focusing on the Fijian archipelago, a region of long-term interest to the researchers, they were able to get a broad, comprehensive overview of the population changes and colonization history of almost all the different ant species in the region. "Being closed, isolated ecosystems, islands are expected to feel the effects of human impact faster, so they are kind of a canary in the coal mine,” notes Dr. Cong Liu, first author on this paper.

However, studying the populations of tropical islands is not without challenges. Often fieldwork can be extremely difficult, and it isn’t easy to do continuous surveys. Therefore, instead of relying on real-time field monitoring, here the team used museum collections built across decades of fieldwork, including both the team’s previous collection efforts and those by other entomologists.

Museumomics: reconstructing ant colonization

One challenge of using museum collections is that DNA degrades over time. Therefore, the researchers had to use special sequencing methods (museumomics) to compare small fragments of DNA. In this study, they sequenced samples of genomes from thousands of ants from over one hundred different confirmed ant species. Using these data, they identified 65 separate instances (colonization events) where new ant species came to the island. These ranged from natural colonization (i.e. arrival of the ants with no human involvement) millions of years ago, to recent human introduction after Fiji became part of global trade networks.

Building on this history, the researchers were able to use their population genetics models to identify the rise or decline in population of different ant groups throughout the Fijian archipelago, noting the decline of endemic species, as well as dramatic increases in population of non-native species in more recent years.

Island endemic species have often evolved traits that make them sensitive to environmental changes, including the arrival of new damaging species. “Most recorded extinctions have historically been from island systems,” adds Dr. Liu.

Going beyond the archipelago

The team hopes that this work can act as inspiration for future work to continue building scientific understanding of insect populations, and to inform conservation efforts. “This study also highlights the importance of biodiversity and museum collections,” explains Professor Alexander Mikheyev of the Australian National University, a senior author on this study. “As our scientific toolbox expands, there is more and more information that we are able to capture from biodiversity collections, so it’s essential that we continue investing in and maintaining these vital resources.”

The team are looking into this locally as well, to measure the biodiversity of Okinawan insect populations in real-time through acoustic monitoring and trapping as part of the Okinawa Environmental Observation Network (OKEON).

“Insects are essential for the environment,” emphasizes Prof. Economo. “As scientists, we need to play our part in their protection, and provide and analyze the relevant data to ensure the long-term integrity of our ecosystems”.

A small selection of the species encountered by the team in Fiji. A) Acropyga sp. FJ02 (endemic) carrying mealybug. B) Hypoponera eutrepta (endemic) carrying larva. C) Tetramorium lanuginosum (introduced). D) Colobopsis dentata (endemic). E) Odontomachus simillimus (Pacific native). F) Colobopsis polynesica (endemic).

Credit

Eli Sarnat

During their fieldwork, the researchers sampled ants in Fiji by using bags to extract them from leaf litter, among other methods. 

Credit

Evan Economo

Journal

Science

DOI

10.1126/science.ads3004

Method of Research

Data/statistical analysis

Article Title

Genomic signatures indicate biodiversity loss in an endemic island ant fauna

Article Publication Date

11-Sep-2025

Inadequate regulatory protections for consumer genetic data privacy in US

American Association for the Advancement of Science (AAAS)

Summary author: Walter Beckwith

In a Policy Forum, Natalie Ram and colleagues discuss the concerning gaps in robust regulatory protection on direct-to-consumer genetic data and biospecimens. After declaring bankruptcy in March 2025, the direct-to-consumer (DTC) genetic testing company, 23andMe, sold the genetic data of over 15 million people worldwide to a nonprofit founded by 23andMe’s own CEO. Although the nature of the sale meant the data remained under familiar leadership, it was controversial and highlighted critical gaps in legal protection for genetic information. Inevitable future commercial sales of such data – potentially with no connection to the original company and its policies – raise the risk of privacy violations. According to Ram et al., companies can revise privacy policies, undermine consumer consent, or share sensitive genetic information with insurers, researchers, or law enforcement, leaving consumers vulnerable. The authors argue that, without stronger safeguards, biospecimens and data may be subject to exploitation, commercialization, or misuse, raising risks that extend to global security. Unlike the European Union, the U.S. lacks a comprehensive federal privacy framework when it comes to safeguards for genetic data. Although the U.S. Congress is exploring legislation, including the Genomic Data Protection Act and the Don’t Sell My DNA Act, Ram et al. highlight how these proposals fall short of offering meaningful protection for consumers. “The 23andMe bankruptcy reminds us how vulnerable people’s DTC genetic data are to sale and potential misuse, given gaps in the law and the predictable vagaries of commercial markets,” write the authors. “Congress and other lawmakers must act to robustly protect DTC genetic data and biospecimens into the future.”

Journal

Science

DOI

10.1126/science.adz7229

Article Title

The precarious future of consumer genetic privacy

Article Publication Date

11-Sep-2025

Pinning down protons in water — a basic science success story

Yale University

New Haven, Conn. — The movement of protons through electrically charged water is one of the most fundamental processes in chemistry. It is evident in everything from eyesight to energy storage to rocket fuel — and scientists have known about it for more than 200 years.

But no one has ever seen it happen. Or precisely measured it on a microscopic scale.

Now, the Mark Johnson lab at Yale has — for the first time — set benchmarks for how long it takes protons to move through six charged water molecules. The discovery, made possible with a highly customized mass spectrometer that has taken years to refine, could have far-reaching applications for researchers in years to come.

“We show what happens in a tiny molecular system where there is no place for the protons to hide,” said Johnson, the Arthur T. Kemp Professor of Chemistry in Yale’s Faculty of Arts and Sciences, and senior author of a new study in the journal Science. “We’re able to provide parameters that will give theorists a well-defined target for their chemical simulations, which are ubiquitous but have been unchallenged by experimental benchmarks.”

Johnson has spent decades developing new tools to analyze chemical reactions, such as the deformation of networks of interconnected water molecules in the presence of electrical charge — a key property of water. But water’s ability to transport positive charge, via protons, has proven elusive — due, in part, to the intrinsically quantum mechanical nature of protons.

“They aren’t polite enough to stay in one place long enough to let us observe them easily,” Johnson said. “They are thought to conduct the charge through an atomic-scale relay mechanism, in which protons jump from molecule to molecule.”

For the study, Johnson and his team studied the proton transfer that occurs when six molecules are attached to 4-aminobenzoic acid carrying an extra proton, a small, positively charged molecule ideally suited for studying water-mediated proton movement.

“To monitor the movement of the charge, you need a special type of organic molecule that can attach a proton in two different locations that are easily differentiated by the color of light they absorb,” said Payten Harville, a Ph.D. student in chemistry in the Yale School of Graduate Studies and co-lead author of the new study, along with fellow Ph.D. student Abhijit Rana. “It’s designed so that the only way for protons to get from one docking site to the other is to hitch a ride on a water network ‘taxi.’”

Johnson’s team runs these molecules through their paces with a specialized mass spectrometer that they’ve adapted to enable multiple interactions with carefully timed pulses of laser light. Located in Yale’s Sterling Chemistry Laboratory, the 30-foot-long device consists of carefully orchestrated piping, electronics, lasers, and a “refrigerator” that chills the molecules down to nearly absolute zero. The tiny assembly of water around the molecule is synthesized, triggered to react, and destructively analyzed for formation of products ten times a second.

“It took years to get the instrument to this point,” Rana said. “And we have finally succeeded in measuring the rate of a chemical reaction that occurs within a finite system.”

Even so, the reaction is so difficult to pin down that the researchers are only able to set parameters for its beginning and end.

“We can’t see it in the intermediate, but we know where the proton started and where it ended up,” Johnson said. “And now we know how long it takes to get there.”

Thien Khuu, a graduate of the Johnson lab who is now a postdoctoral fellow at the University of Southern California, is co-author of the study.

Funding for the research came from the U.S. Department of Energy, the U.S. Air Force Office of Scientific Research, a John C. Tully Graduate Research grant, and the National Institutes of Health.

Journal

Science

DOI

10.1126/science.ady1723

Article Title

Microcanonical kinetics of water-mediated proton transfer in microhydrated 4-aminobenzoic acid

Article Publication Date

11-Sep-2025

Scientists reveal how the brain uses objects to find direction

Study shows how visual landmarks tune the brain’s internal compass

McGill University

Visual objects sharpen the representation of head direction — image:
Of all visually
responsive regions, the most objectpreferring
areas belonged to the spatial
navigation system. Electrophysiological
analysis in one of the identified regions,
the postsubiculum, indicated that when
an animal faces a visual landmark, HD
encoding is refined. W, west; N, north;
E, east; S, south.
view more
Credit: Siegenthaler et al

We take our understanding of where we are for granted, until we lose it. When we get lost in nature or a new city, our eyes and brains kick into gear, seeking familiar objects that tell us where we are.

How our brains distinguish objects from background when finding direction, however, was largely a mystery. A new study provides valuable insight into this process, with possible implications for disorientation-causing conditions such as Alzheimer’s.

The scientists, based at The Neuro (Montreal Neurological Institute-Hospital) of McGill University and the University Medical Center Göttingen, ran an experiment with mice using ultrasound imaging to measure and record brain activity. The mice were shown visual stimuli, either an object or a scrambled image showing no distinct object.

They found a small number of brain areas that fired especially when the mouse looked at objects. These areas were found in a brain region called the postsubiculum which specializes in keeping track of where the animal is facing at any given time. Each direction activates a specific cell in the postsubiculum. Objects in the mice’s vision increased the firing of the cell responsible for the direction in which the mouse was looking. They also inhibited cells responsible for directions where the mouse was not looking. Together, this activity reinforced the mouse’s perception of where it was relative to the object.

While the postsubiculum was particularly sensitive to the presence of objects in the mouse’s vision, other brain regions were not, suggesting that object recognition is particularly important to the brain’s understanding of where it is and where the animal is looking.

This finding offers clues as to why humans with diseases such as dementia and Alzheimer’s often lose track of where they are. A recent study from Oxford University has shown that the accumulation of tau protein-a hallmark of Alzheimer’s-happens first in the brain regions responsible for spatial orientation.

“A very useful aspect of our study is it presents a very high-level understanding of two systems that interact together-the visual and spatial recognition systems,” says Stuart Trenholm, a researcher at The Neuro and the paper’s co-senior author. “We have a decent understanding now of how they modulate each other. They are both very high-level brain functions and lot of these neurodegenerative disorders lead to disconnections between these states, so that will be interesting to look into in the future.”

“Our results are incredibly surprising,” says Adrien Peyrache, a researcher at The Neuro and the paper’s co-senior author. “Nobody would have predicted that object processing would occur in the navigation system and not in the visual cortex. For the first time, we have an inside-the-brain perspective of what an object is, and how we use an object to get a sense of the world around us.”

Their results were published in the journal Science on Sept. 11, 2025.

About The Neuro

The Neuro – The Montreal Neurological Institute-Hospital – is a bilingual, world-leading destination for brain research and advanced patient care. Since its founding in 1934 by renowned neurosurgeon Dr. Wilder Penfield, it has grown to be the largest specialized neuroscience research and clinical center in Canada, and one of the largest in the world. The seamless integration of research, patient care, and training of the world’s top minds make The Neuro uniquely positioned to have a significant impact on the understanding and treatment of nervous system disorders. It was the first academic institute in the world to fully adopt Open Science, to help accelerate the generation of knowledge and discovery of novel effective treatments for brain disorders. The Neuro is a McGill University research and teaching institute and part of the Neuroscience Mission of the McGill University Health Centre. For more information, please visit www.theneuro.ca

Journal

Science

DOI

10.1126/science.adu9828

Method of Research

Experimental study

Subject of Research

Animals

Article Title

Visual objects refine head direction coding

Article Publication Date

11-Sep-2025

Humans sense a collaborating robot as part of their “extended” body

The research conducted between Italy and the USA aims to improve robot design. Published in the journal iScience, the study was funded by the ERC

Istituto Italiano di Tecnologia - IIT

Slicing a bar of soap together — image:
Researchers from the Istituto Italiano di Tecnologia (IIT) in Genoa (Italy) and Brown University in Providence (USA) have discovered that people sense the hand of a humanoid robot as part of their body schema, particularly when it comes to carrying out a task together, like slicing a bar of soap.
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Credit: IIT-Istituto Italiano di Tecnologia

Genoa (Italy), 11 September 2025 - Researchers from the Istituto Italiano di Tecnologia (IIT) in Genoa (Italy) and Brown University in Providence (USA) have discovered that people sense the hand of a humanoid robot as part of their body schema, particularly when it comes to carrying out a task together, like slicing a bar of soap. The study has been published in the journal iScience and can pave the way for a better design of robots that have to function in close contact with humans, such as those used in rehabilitation.

The project, led by Alessandra Sciutti, IIT Principal Investigator of the CONTACT unit at IIT, in collaboration with Brown University professor Joo-Hyun Song, explored whether unconscious mechanisms that shape interactions between humans also emerge in interactions between a person and a humanoid robot.

Researchers focused on a phenomenon known as the “near-hand effect”, in which the presence of a hand near an object alters visual attention of a person, because the brain is preparing to use the object. Moreover, the study considers the human brain's ability to create its “body schema” to move more efficiently in the surrounding space, by integrating objects into it as well.

Through an unconscious process shaped by external stimuli, the brain builds a “body schema” that helps us avoid obstacles or grab objects without looking at them. Any tools can become part of this internal map as long as they are useful for a task, like a tennis racket that feels like an arm extension to the player who uses it daily. Since body schema is constantly evolving, the research team led by Sciutti explored whether a robot could also become part of it.

Giulia Scorza Azzarà, PhD student at IIT and first author of the study, designed and analyzed the results of experiments where people carried out a joint task with iCub, the IIT’s child-sized humanoid robot. They sliced a bar of soap together by using a steel wire, alternately pulled by the person and the robotic partner.

After the activity, researchers verified the integration of the robotic hand into the body schema, quantifying the near hand effect with the Posner cueing task. This test challenges participants to press a key as quickly as possible to indicate on which side of the screen an image appears, while an object placed right next to the screen influences their attention. Data from 30 volunteers showed a specific pattern: participants reacted faster when images appeared next to the robot’s hand, showing that their brains had treated it much like a near hand. Thanks to control experiments, researchers proved that this effect appeared only in those who had sliced the soap with the robot.

The strength of the near hand effect also depended on how the humanoid robot moved. When the robot’s gestures were broad, fluid, and well synchronized with the human ones, the effect was stronger, resulting in a better integration of iCub’s hand into the participant’s body schema. Physical closeness between the robotic hand and the person also played a role: the nearer the robot’s hand was to the participant during the slicing task, the greater the effect.

To assess how participants perceived the robot after working together on the task, researchers gathered information through questionnaires. The results show that the more participants saw iCub as competent and pleasant, the more intense the cognitive effect was. Attributing human-like traits or emotions to iCub further boosted the hand’s integration in the body schema; in other words, partnership and empathy enhanced the cognitive bond with the robot.

The team carried out experiments with a humanoid robot under controlled conditions, paving the way for a deeper understanding of human-machine interactions. Psychological factors will be essential to designing robots able to adapt to human stimuli and able to provide a more intuitive and effective robotic experience. These are crucial features for application of robotics in motor rehabilitation, virtual reality, and assistive technologies.

The research is part of the ERC-funded wHiSPER project, coordinated by IIT’s CONTACT (COgNiTive Architecture for Collaborative Technologies) unit.

Journal

iScience

DOI

10.1016/j.isci.2025.112791

Method of Research

Experimental study

Subject of Research

People

Article Title

Collaborating with a robot biases human spatial attention

XAOS THEORY

Turbulence with a twist

University of California - San Diego

Turbulence is everywhere, yet much about the nature of turbulence remains unknown. During the last decade, physicists have discovered how fluids in a pipe or similar geometry transition from a smooth, laminar state to a turbulent state as their speed increases. Surprisingly, in the newly emerging consensus, the process could be understood using statistical mechanics, not fluid mechanics, and was mathematically equivalent to the way in which water percolates down through a coffee filter.

In a new twist, UC San Diego researchers Guru K. Jayasingh and Nigel Goldenfeld have now predicted that if the pipe is sufficiently curved, the transition can become discontinuous, with the turbulent fraction undergoing a jump beyond a critical flow velocity. This jump is mathematically similar to the way in which water can suddenly and discontinuously turn into ice if cooled below the freezing temperature. The new framework — so-called tricritical directed percolation — encompasses both the emerging consensus and very recent experiments, as well as making new predictions.

Their work shows that the whole apparatus of phase transitions, originally developed for thermodynamics, and now foundational in materials science, chemistry and physics, can be applied to certain transitional phenomena in fluid mechanics.

The study was published September 3, 2025 in Physical Review Letters. The research was carried out by Guru K. Jayasingh and Nigel Goldenfeld. Their research was funded by the Simons Foundation (662985).

Read the study: Tricritical Directed Percolation Controls the Laminar-Turbulent Transition in Pipes with Body Forces.

Journal

Physical Review Letters

DOI

10.1103/46g3-n7cx

Method of Research

Data/statistical analysis

Article Title

Tricritical Directed Percolation Controls the Laminar-Turbulent Transition in Pipes with Body Forces

Article Publication Date

13-Sep-2025