Bluesky is similarly structured to other social media, but with some unusual features

Researchers found spikes in new Bluesky users, who seem relatively left-leaning, correlated with news about X

Peer-Reviewed Publication

PLOS

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A collage of entirely fictional users announcing their migration from Twitter to Bluesky.

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Credit: Dorian Quelle, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

A comprehensive analysis of social media platform Bluesky provides insights into its structure, polarization and political leanings, in a new study published in open-access journal PLOS One on February 26, 2025, by Dorian Quelle and Alexandre Bovet, from the University of Zurich, Switzerland.

Many social media platforms rely on proprietary algorithms to recommend content, a methodology that has received increasing backlash over the years. However, Bluesky instead allows users the ability to curate their experiences. The authors of the present study analyzed the social media site’s trajectory from its invite-only launch in February 2023 to the 5.7 million users hosted in May 2024, examining its network structure, polarization, and political leanings of its users.

Despite Bluesky’s unique structure, the researchers found that the user interactions on Bluesky are similar to those of many other platforms, in that a few highly active users dominate the landscape.

The researchers tracked spikes in user sign ups, which often correlated with news related to X (formerly known as Twitter). For example, X’s current owner Elon Musk announced in September 2023 that X would require users to pay a fee, and Bluesky saw its highest number of new users over the next two days. The second largest spike in new Bluesky users they observed happened in July 2023 when X users experienced a bug interrupting their access to the platform.

These reactions demonstrate that many X users see Bluesky as the closest alternative. However, Bluesky appears to be relatively left-leaning: of links shared by Bluesky users, over 60% led to left-leaning websites. Centrist sources made up about 20% of links shared, and only about 8% of links led to right-leaning websites.

Despite this political alignment, the researchers found that Bluesky users particularly diverged on the topic of the Israel-Palestine conflict. Using a machine learning algorithm to categorize relevant posts as pro-Israel or pro-Palestine, the researchers found that prior to the October 7 attacks on Israel and the subsequent retaliation, most posts about Israel-Palestine relations were neutral. Afterwards, there was a sharp split between users, with a greater number of posts skewing more pro-Palestine over time.

Given its similarities to larger social media sites, Bluesky offers a unique opportunity to study how these networks grow from their beginnings and change over time. The polarization around the Israel-Palestine conflict also demonstrates that divisions can occur even in networks that are otherwise politically aligned, and future research could probe these splits.

The authors add: “Our study shows the potential of open social media platforms for investigating the impact of their design and algorithms on collective human behavior.”

 

 

In your coverage, please use this URL to provide access to the freely available article in PLOS One: https://plos.io/3QgOno6

Citation: Quelle D, Bovet A (2025) Bluesky: Network topology, polarization, and algorithmic curation. PLoS ONE 20(2): e0318034. https://doi.org/10.1371/journal.pone.0318034

Author countries: Switzerland

Funding: The author(s) received no specific funding for this work.

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Journal

PLOS One

DOI

10.1371/journal.pone.0318034 

Method of Research

Observational study

Subject of Research

People

Article Title

Bluesky: Network topology, polarization, and algorithmic curation

Article Publication Date

26-Feb-2025

 

Fossil eggshells from Utah's Cedar Mountain Formation include Cretaceous period eggs from 3 feathered bird-like dinosaurs, 2 herbivorous dinosaurs, and a crocodile-like species found for the first time outside Europe

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Graphical abstract of the manuscript.

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Credit: Ryan Tucker and Josh Hedge, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

 

Article URL: https://plos.io/42XpPYx

Article title: Fossil eggshell diversity of the Mussentuchit Member, Cedar Mountain Formation, Utah

Author countries: U.S., South Africa

Funding: This research was supported by Canyonlands Natural History Association, Global Creatures, and MagicSpace Entertainment (2014–2015) and the National Science Foundation (awards 1925973 to LEZ and 1925884 to PJM). Any opinions, findings, conclusions, or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation or other funding agencies. https://www.nsf.gov https://cnha.org https://global-creatures.com https://www.magicspace.net.

Fossil eggshell diversity of the Mussentuchit Member, Cedar Mountain Formation, Utah 

Prospecting for eggshells in Utah, 2020.

Credit

Lindsay Zanno, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

Features of Undulatoolithus fragment NCSM 33729. A) surface view of NCSM 33729. Red line indicates where thin section was made (dashed where not seen in the radial thin sections). B) NCSM 33729 in radial thin section. Tailed scale bar marks very high, undulating ornamentation. Gradational ML/CL boundary marked with solid black lines; accretion lines in CL shown with dashed black lines; arrows and black fill show infilled pores. C) radial thin section under crossed polars. Scale bars equal 10 mm.

Credit

Hedge et al., 2025, PLOS One, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

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Journal

PLOS One

DOI

10.1371/journal.pone.0314689 

Article Title

Fossil eggshell diversity of the Mussentuchit Member, Cedar Mountain Formation, Utah

Article Publication Date

26-Feb-2025

RED STATES

Study: Extreme heat may speed up aging in older adults

People in neighborhoods that experience more days of high heat show faster aging at the molecular level than residents of cooler regions, say USC researchers

University of Southern California

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Number of Heat Days at Extreme Caution+ (≥90°F) across the U.S. Heat is measured using the Heat Index. Data represent the yearly average from 2010 to 2016.

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Credit: USC/Eunyoung Choi

A new USC Leonard Davis School of Gerontology study suggests greater exposure to extreme heat may accelerate biological aging in older adults, raising new concerns about how climate change and heat waves could affect long-term health and aging at the molecular level.

People in neighborhoods that experience more days of high heat show greater biological aging on average than residents of cooler regions, said Jennifer Ailshire, senior author of the study and professor of gerontology and sociology at the USC Leonard Davis School.

Biological age is a measure of how well the body functions at the molecular, cellular, and system levels, as opposed to chronological age based on one’s birthdate; having a biological age greater than one’s chronological age is associated with higher risk for disease and mortality. While exposure to extreme heat has itself long been associated with negative health outcomes, including increased risk of death, heat’s link to biological aging has been unclear.

Measuring epigenetic changes

Ailshire and her coauthor Eunyoung Choi, USC Leonard Davis PhD in Gerontology alumna and postdoctoral scholar, examined how biological age changed in more than 3,600 Health and Retirement Study (HRS) participants aged 56 and older from throughout the U.S. Blood samples taken at various time points during the six-year study period were analyzed for epigenetic changes, or changes in the way individual genes are turned “off” or “on” by a process called DNA methylation.

The researchers used mathematical tools called epigenetic clocks to analyze methylation patterns and estimate biological ages at each time point. They then compared participants’ changes in biological age to their location’s heat index history and number of heat days reported by the National Weather Service from 2010 to 2016.

The National Weather Service Heat Index Chart categorizes heat index values into three levels based on the potential risk of adverse health effects. The “Caution” level includes heat index values ranging from 80°F to 90°F, the “Extreme Caution” level includes values between 90°F and 103°F, and the “Danger” level includes values between 103°F and 124°F. Days in all three levels were included as heat days in the study.

The analysis revealed a significant correlation between neighborhoods with more days of extreme heat and individuals experiencing greater increases in biological age, Choi said. This correlation persisted even after controlling for socioeconomic and other demographic differences, as well as lifestyle factors such as physical activity, alcohol consumption and smoking, she added.

“Participants living in areas where heat days, as defined as Extreme Caution or higher levels (≥90°F), occur half the year, such as Phoenix, Arizona, experienced up to 14 months of additional biological aging compared to those living in areas with fewer than 10 heat days per year,” she said. “Even after controlling for several factors, we found this association. Just because you live in an area with more heat days, you're aging faster biologically.”

All three epigenetic clocks employed in the study – PCPhenoAge, PCGrimAge, and DunedinPACE – revealed this association when analyzing epigenetic aging over a 1- to 6-year period. PCPhenoAge also showed the association after short (7 days) and medium (30-60 days) periods of time, indicating that heat-related epigenetic changes could happen relatively quickly, and some of them may accumulate over time.

Climate implications for communities

Older adults are particularly vulnerable to the effects of high heat, Ailshire said. She noted that the study used heat index, rather than just air temperature, to take relative humidity into account as they analyzed results.

“It's really about the combination of heat and humidity, particularly for older adults, because older adults don't sweat the same way. We start to lose our ability to have the skin-cooling effect that comes from that evaporation of sweat,” she explained. “If you’re in a high humidity place, you don’t get as much of that cooling effect. You have to look at your area’s temperature and your humidity to really understand what your risk might be.”

The next steps for the researchers will be to determine what other factors might make someone more vulnerable to heat-related biological aging and how it might connect to clinical outcomes. In the meantime, the study results could also prompt policymakers, architects, and others to keep heat mitigation and age-friendly features in mind as they update cities’ infrastructure, from placing sidewalks and building bus stops with shade in mind to planting more trees and increasing urban green space, Ailshire said.

“If everywhere is getting warmer and the population is aging, and these people are vulnerable, then we need to get really a lot smarter about these mitigation strategies,” she said.

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The study, “Ambient Outdoor Heat and Accelerated Epigenetic Aging among Older Adults in the U.S.,” appeared in the journal Science Advances on February 26, 2025. Funding for the study included the USC/UCLA Center on Biodemography and Population Health through a grant from the National Institute on Aging, National Institutes of Health (P30AG017265) and The Network on Life Course Health Dynamics and Disparities in 21st Century America funded by the National Institute on Aging, National Institutes of Health (R24AG045061).

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Journal

Science Advances

DOI

10.1126/sciadv.adr0616 

Method of Research

Data/statistical analysis

Subject of Research

People

Article Title

Ambient Outdoor Heat and Accelerated Epigenetic Aging among Older Adults in the US

Article Publication Date

26-Feb-2025

Morphing robot turns challenging terrain to its advantage

A bioinspired robot developed at EPFL can change shape to alter its own physical properties in response to its environment, resulting in a robust and efficient autonomous vehicle as well as a fresh approach to robotic locomotion.

Ecole Polytechnique Fédérale de Lausanne

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The morphing Good Over All Terrains (GOAT) robot in sphere mode © CREATE EPFL

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Credit: © CREATE EPFL

From mountain goats that run up near-vertical rock faces to armadillos that roll into a protective ball, animals have evolved to adapt effortlessly to changes in their environment. In contrast, when an autonomous robot is programmed to reach a goal, each variation in its pre-determined path presents a significant physical and computational challenge.

Researchers led by Josie Hughes in the CREATE Lab in EPFL’s School of Engineering wanted to develop a robot that could traverse diverse environments as adeptly as animals by changing form on the fly. With GOAT (Good Over All Terrains) they have achieved just that – and created a new paradigm for robotic locomotion and control in the process.

Thanks to its flexible yet durable design, GOAT can spontaneously morph between a flat ‘rover’ shape and a sphere as it moves. This allows it to switch between driving, rolling, and even swimming, all while consuming less energy than a robot with limbs or appendages.

“While most robots compute the shortest path from A to B, GOAT considers the travel modality as well as the path to be taken,” Hughes explains. “For example, instead of going around an obstacle like a stream, GOAT can swim straight through. If its path is hilly, it can passively roll downhill as a sphere to save both time and energy, and then actively drive as a rover when rolling is no longer beneficial.”

The research has been published in Science Robotics.

Compliance is key

To design their robot, the CREATE team took inspiration from across the animal kingdom, including spiders, kangaroos, cockroaches, and octopuses.The team’s bioinspired approach led to a design that is highly compliant, meaning it adapts in response to interaction with its environment, rather than remaining rigid. This compliance means that GOAT can actively alter its shape to change its passive properties, which range from more flexible in its ‘rover’ configuration, to more robust as a sphere.

Built from inexpensive materials, the robot’s simple frame is made of two intersecting elastic fiberglass rods, with four motorized rimless wheels. Two winch-driven cables change the frame’s configuration, ultimately shortening like tendons to draw it tightly into a ball. The battery, onboard computer, and sensors are contained in a payload weighing up to 2 kg that is suspended in the center of the frame, where it is well protected in sphere mode – much as a hedgehog protects its underbelly.

The path of least resistance

CREATE Lab PhD student Max Polzin explains that compliance also allows GOAT to navigate with minimal sensing equipment. With only a satellite navigation system and a device for measuring the robot’s own orientation (inertial measurement unit), GOAT carries no cameras onboard: it simply does not need to know exactly what lies in its path.

“Most robots that navigate extreme terrain have lots of sensors to determine the state of each motor, but thanks to its ability to leverage its own compliance, GOAT doesn’t need complex sensing. It can leverage the environment, even with very limited knowledge of it, to find the best path: the path of least resistance,” Polzin says.

Future research avenues include improved algorithms to help exploit the unique capabilities of morphing, compliant robots, as well as scaling GOAT’s design up and down to accommodate different payloads. Looking ahead, the researchers see many potential applications for their device, from environmental monitoring to disaster response, and even extraterrestrial exploration.

“Robots like GOAT could be deployed quickly into uncharted terrain with minimal perception and planning systems, allowing them to turn environmental challenges into computational assets,” Hughes says. “By harnessing a combination of active reconfiguration and passive adaptation, the next generation of compliant robots might even surpass nature’s versatility.”

The morphing Good Over All Terrains (GOAT) robot in rover mode © CREATE EPFL

 

The morphing Good Over All Terrains (GOAT) robot in sphere mode © CREATE EPF

Journal

Science Robotics

DOI

10.1126/scirobotics.adp6419 

Method of Research

Experimental study

Article Title

Robotic Locomotion through Active and Passive Morphological Adaptation in Extreme Outdoor Environments

Article Publication Date

26-Feb-2025

A springtail-like jumping robot

Diminutive device can leap 23 times its body length

Harvard John A. Paulson School of Engineering and Applied Sciences

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The Harvard Ambulatory Microrobot modified with its springtail-inspired jumping mechanism.

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Credit: Harvard Microrobotics Laboratory

Springtails, small bugs often found crawling through leaf litter and garden soil, are expert jumpers. Inspired by these hopping hexapods, roboticists in the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have made a walking, jumping robot that pushes the boundaries of what small robots can do.

Published in Science Robotics, the research glimpses a future where nimble microrobots can crawl through tiny spaces, skitter across dangerous ground, and sense their environments without human intervention. 

The new Harvard robot was created in the lab of Robert J. Wood, the Harry Lewis and Marlyn McGrath Professor of Engineering and Applied Sciences at SEAS. It is a modification of the Harvard Ambulatory Microrobot (HAMR), a microrobotic platform originally modeled after the dexterous, hard-to-kill cockroach. Now, HAMR is outfitted with a robotic furcula – the forked, tail-like appendage tucked under a springtail’s body that it pushes off the ground to send it Simone Biles-ing into the air.

“Springtails are interesting as inspiration, given their ubiquity, both spatially and temporally across evolutionary scales,” Wood said. “They have this unique mechanism that involves rapid contact with the ground, like a quick punch, to transfer momentum and initiate the jump.”

To go airborne, the robot uses what’s called latch-mediated spring actuation, in which potential energy is stored in an elastic element – the furcula – that can be deployed in milliseconds like a catapult. This physical phenomenon is found time and again in nature, not just in springtails: from the flicking tongue of a chameleon to the prey-killing appendage of a mantis shrimp. 

Wood’s team previously created a mantis shrimp-inspired punching robot. “It seemed natural to try to explore the use of a similar mechanism, along with insights from springtail jumps, for small jumping robots,” Wood said. 

The springtail’s furcula is also elegantly simple, composed of just two or three linked units. “I think that simplicity is what initially charmed me into exploring this type of solution,” said first author and former SEAS research fellow Francisco Ramirez Serrano.

The team used streamlined microfabrication workflows pioneered in the Wood lab to develop the palm-sized, paper clip-light robot that can walk, jump, climb, strike, and even scoop up objects.

The robot demonstrates some of the longest and highest jumps of any existing robot relative to body length; its best performance is 1.4 meters, or 23 times its length. By contrast, a similar robot can jump twice as far but outweighs the Harvard robot by 20 times.

“Existing microrobots that move on flat terrain and jump do not possess nearly the agility that our platform does,” Serrano said.

The team incorporated detailed computer simulations into the design of the robot to help it land optimally every time, precisely controlling for the lengths of its linkages, the amount of energy stored in them, and the orientation of the robot before takeoff.

Packing all manner of athletic abilities into one lightweight robot has the team excited for a future where robots like theirs could traverse places humans can’t or shouldn’t. 

“Walking provides a precise and efficient locomotion mode but is limited in terms of obstacle traversal,” Wood said. “Jumping can get over obstacles but is less controlled. The combination of the two modes can be effective for navigating natural and unstructured environments.”

The research was supported by the U.S. Army Research Office under grant No. W911NF1510358.

Jumping video [VIDEO] | 

Still image of the springtail-inspired robot. 

Credit

Harvard Microrobotics Laboratory

Journal

Science Robotics

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

A springtail-inspired multi-modal walking-jumping microrobot

Article Publication Date

26-Feb-2025