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Paper Roundup

Paper Roundup October 2025: dark matter, emergence, and dinosaur mummies

Papers on big questions at the frontiers of science, curated by hand each month

Elise Cutts

Elise Cutts

— 16 min read
Paper Roundup October 2025: dark matter, emergence, and dinosaur mummies
Magpies are notorious thieves, but I like to think they see themselves as curators. Art: American Magpie by Robert Havell after John James Audubon (1837) in the National Gallery of Art

Every month, I publish a curated list of fascinating, groundbreaking inflammatory, or otherwise bold new scholarship on "big questions" at the frontiers of science. Inclusion is not endorsement. Think something should be included in next month's paper roundup? Shoot me an email at elise@reviewertoo.com. 

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Highlights

Did we just spot a tiny blob of dark matter?

A million-solar-mass object detected at a cosmological distance using gravitational imaging (Nature Astronomy, October 9) by D. M. Powell, J. P. McKean, S. Vegetti, C. Spingola, S. D. M. White, and C. D. Fassnacht

A tiny twist in an already-twisted image of a distant galaxy might be a little blob of dark matter. The blob is about 1 million times as massive as the sun. If it is a lump of dark matter, that would be small — 100 times smaller than the smallest dark object found before. But it might also be a stealthy dwarf galaxy. If researchers can find more of these little dark blobs, it could help scientists figure out what dark matter actually is.

Dark matter is "dark" because it doesn't interact with light. But it does make itself known via another force: gravity. Scientists think it must exist because if it didn't, plenty of things we can directly observe wouldn't make sense, especially when it comes to the structure and behavior of galaxies. Gravitational lensing — the way gravity warps light — can also reveal dark matter. When something massive sits between our telescopes and a distant light source, its gravity warps our view. So by measuring the geometry of the warped source, we can infer thins about the mass in-between — even if we can't see it at all.

In this study, researchers used radio telescopes from all around the world to scrutinize a smeared-out, gravitationally lensed galaxy. And in that smeared-out light, they found an extra little kink: the gravitational fingerprint of a mysterious dark object about 1 million times the mass of our Sun. That might sound big, but the mystery blob is the smallest dark object observed yet.

Astronomers Find Mystery Dark Object in Distant Universe
Using a global network of telescopes, astronomers have detected the lowest-mass dark object yet found in the universe. Finding more such objects and understanding their nature could rule out some theories about the nature of dark matter, the mystery substance that makes up about a quarter of the universe. The work is described in two papers published Oct. 9 in Nature Astronomy and Monthly Notices of the Royal Astronomical Society.
UC DavisAndy Fell

Engineering (causal) emergence

Engineering Emergence (arXiv preprint, October 3) by Abel Jansma and Erik Hoel

Emergence is one of those words that everyone uses and nobody has a good definition for — at least, not a scientific definition wrapped up in mathematics. That's starting to change. Over the past decade or so, several researchers have made some very interesting attempts to define emergence in useful terms. You might have expected this kind of work to come out of the complexity science community. But interestingly, that's not what happened. Rather, it's consciousness researchers — think people like Anil Seth and colleagues — who are doing the hard thinking on emergence lately. And that includes Erik Hoel, who helped develop the integrated information theory of consciousness before borrowing parts of IIT for a new theory of emergence.

Hoel introduced his "causal emergence" theory 8 years ago — for a crash course, see Natalie Wolchover's 2017 Quanta piece. Now, after a hiatus from science, Hoel is back with new work that claims to address several common criticisms of causal emergence and expands the framework in interesting new ways. This is the second paper in that effort.

To me, the title "Engineering emergence" obscures this paper's most interesting contribution to discourse around complexity and emergence: defining complexity in terms of emergence. Hoel essentially provides a) a way to identify (or engineer) macroscale levels (coarse-grainings) of a system that could reasonably be considered "emergent" because of their causal properties and then b) encourages us to think about systems as having an architecture of emergent levels. A more complex system has more emergent macroscales — milk swirling into coffee is more complex than thoroughly-mixed coffee because there are more scales at which it is causally emergent. I like this, because it puts the idea of "multi-scale organization" or "heierarchies of scale" as a hallmark of complex systems on firm theoretical footing. We can do better than a nesting doll metaphor.

Die Wahrheit ist eine Matroschka (the truth is a nesting doll) Image: User: Fanghong via Wikimedia Commons

Of course, I'm a layperson who can't dig into the math myself. So take my impressions with a hefty grain of salt. I haven't had the chance to speak with many experts about causal emergence yet, but my impression is that it hasn't really caught on in the complexity community. I'd love to know why.

For those interested in digging deeper, Hoel wrote a plain-language walkthrough of the paper on his Substack:

I Figured Out How to Engineer Emergence
What’s come of my return to science
The Intrinsic PerspectiveErik Hoel

Islands of dreamless sleep

Hemispherotomy leads to persistent sleep-like slow waves in the isolated cortex of awake humans (PLOS Biology, October 16, 2025) by Michele Angelo Colombo, Jacopo Favaro, Ezequiel Mikulan, Andrea Pigorini, Flavia Maria Zauli, Ivana Sartori, Piergiorgio d’Orio, Laura Castana, Irene Toldo, Stefano Sartori, Simone Sarasso, Tim Bayne, Anil K. Seth, and Marcello Massimini.

Speaking of the consciousness community, one of the more interesting things to have come out of it in recent years is a set of quantitative measurements correlated with consciousness. These have allowed scientists to, among other things, realize that an alarmingly high percentage (something like 20%!) of patients who appear to be in a coma or otherwise totally unresponsive — basically, people who look dead to the outside world — are still conscious. Researchers also have a much better hold on the types of brain activity patterns associated with stakes like wakefulness and sleep.

This study uses those tools to ask a frankly disturbing question: could a brain hemisphere that's been entirely cut off from the world still conscious?

Finding islands in the uncharted waters of consciousness - CIFAR
Can consciousness persist in brains that are totally cut off from the outside world?
CIFARAlison Rutka

If so, that'd mean there are people walking around with around trapped, locked-in second consciousnesses in their skulls. Some kids with severe epilepsy undergo a procedure called hemispherotomy that almost entirely severs one brain hemisphere from the rest of the body. This surgery goes far beyond the more famous split-hemisphere procedure, which prevents the left and right hemispheres from talking to each other but otherwise keeps them intact. It severs one hemisphere entirely from sensory and motor pathways. Basically, it's hooked up to blood vessels but basically nothing else. It not only cannot communicate with the other hemisphere, it cannot act or perceive.

For researchers, this dramatic procedure is a chance to look for "islands of awareness" — loci of conscious experience cut off from the world. Is it even possible to be conscious without having a world to interact with? Considering how central world modeling is to several lines of thinking about consciousness, it's not unreasonable to think the answer could be "no."

This study reports "slow wave" patterns of brain activity in the isolate hemispheres of hemispherotomy patients that look quite a bit like those seen in dreamless sleep or sedation. Slow waves don't always mean someone is unconscious. But they're a good hit — good enough, at least, to be used in clinical settings to adjust anesthesia during surgery and to judge how conscious unresponsive patients might be.

I find this, somehow, reassuring. It's not conclusive evidence that the isolated hemisphere essentially goes to sleep. But it does show that the isolated hemisphere is clearly in a different, probably less wakeful and possibly even unconscious state of being than the connected one. If the isolated hemisphere is conscious at all, I wonder if it would become hyper-aware of the limited input it does receive from the outside world via the blood. What would it be like to inhabit a world defined only by blood sugar, blood oxygen, nutrients, hormones — and perhaps a few memories, scraps of the half-forgotten world of vivid sensory experience from before everything went black?

Dinosaur mummies

Duck-billed dinosaur fleshy midline and hooves reveal terrestrial clay-template “mummification” (Science, October 23) by Paul C. Sereno, Evan T. Saitta, Daniel Vidal, Nathan Myhrvold, María Ciudad Real, Stephanie L. Baumgart, Lauren L. Bop, Tyler M. Keillor, Marcus Eriksen, and Kraig Derstler

Need I really say more?

Sereno et al. 2025 (Science)

Alien topography from alien skies

Probing the geological setting of exoplanets through atmospheric analysis: Using Mars as a test case (Icarus, October 16) by Monica Rainer, Evandro Balbi, Francesco Borsa, Paola Cianfarra, Avet Harutyunyan, and Silvano Tosi.

I really do try to keep tabs on exoplanet astronomy. So I was surprised to see this paper propose something that I've literally never heard someone talk about before: using observations of a planet's atmosphere to constrain its surface topography.

Using chemicals in an exoplanet's sky to determine whether there's a mountain range or canyon down there on the ground? Sounds out-there. But the authors of this paper claim it should be feasible and use Mars as a test case. The core idea is sounds quite clever. The strength of the spectral "fingerprints" of chemicals in a planet's atmosphere can depend on the thickness of the atmosphere. So seeing weaker fingerprints in some patches compared to others might hint at different topography. Being able to do this for exoplanets at all hinges on future telescopes that could make spatially-resolved observations of the compositions of exoplanet atmospheres, which we're quite far away from. I just find this a fun idea and love that people are trying to be this creative about squeezing as much information about planets out of very, very limited observations.

Linguistic side-note: this paper uses the jargon word "telluric planet" instead of "terrestrial planet" and I am truly at a loss for why. I have never once heard that term before and don't see what advantage it has over terrestrial. Leave a comment if you know what's going on here!

It took us until 2025 to...

Comparative analysis of human and mouse ovaries across age (Science, October 9) by Eliza A. Gaylord, Mariko H. Foecke, Ryan M. Samuel, Bikem Soygur, Angela M. Detweiler, Tara I. McIntyre, Leah C. Dorman, Michael Borja, Amy E. Laird, Ritwicq Arjyal, Juan Du, James M. Gardner, Norma Neff, Faranak Fattahi, and Diana J. Laird

... get serious about matching up the biology of human ovaries to mouse ovaries. For context, mice and rats are the go-to model organisms for studying reproductive aging, even though they don't go through menopause like humans do (to be fair, few animals do).

This honestly seems like something we should have figured out a decade ago. But here we are.

Disappointed.

A special issue on origins of life

Theme issue: ‘Origins of life: the possible and the actual’ (Phil. Trans. R. Soc. B, October 2) compiled by Ricard Solé, Chris Kempes and Susan Stepney

Lots of origin of life papers this month! Instead of listing out every paper in this special issue below, I just want to link to the collection here. Highlights include:

There is no time telescope
The Mars that may have hosted life long ago is our neighbor in space only.
Reviewer, tooElise Cutts

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The Rest

The Universe

Planets and Habitability

Earth

  • Destabilization of Earth system tipping elements (Nature Geoscience, October 1) by Niklas Boers, Teng Liu, Sebastian Bathiany, Maya Ben-Yami, Lana L. Blaschke, Nils Bochow, Chris A. Boulton, Timothy M. Lenton, Andreas Morr, Da Nian, Martin Rypdal, and Taylor Smith

Biosignatures and SETI

Origins and Artificial Life

Evolution

  • Evidence for improved DNA repair in long-lived bowhead whale (Nature, October 29) by Denis Firsanov, Max Zacher, Xiao Tian, Todd L. Sformo, Yang Zhao, Gregory Tombline, J. Yuyang Lu, Zhizhong Zheng, Luigi Perelli, Enrico Gurreri, Li Zhang, Jing Guo, Anatoly Korotkov, Valentin Volobaev, Seyed Ali Biashad, Zhihui Zhang, Johanna Heid, Alexander Y. Maslov, Shixiang Sun, Zhuoer Wu, Jonathan Gigas, Eric C. Hillpot, John C. Martinez, Minseon Lee, Alyssa Williams, Abbey Gilman, Nicholas Hamilton, Ekaterina Strelkova, Ena Haseljic, Avnee Patel, Maggie E. Straight, Nalani Miller, Julia Ablaeva, Lok Ming Tam, Chloé Couderc, Michael R. Hoopmann, Robert L. Moritz, Shingo Fujii, Amandine Pelletier, Dan J. Hayman, Hongrui Liu, Yuxuan Cai, Anthony K. L. Leung, Zhengdong Zhang, C. Bradley Nelson, Lisa M. Abegglen, Joshua D. Schiffman, Vadim N. Gladyshev, Carlo C. Maley, Mauro Modesti, Giannicola Genovese, Mirre J. P. Simons, Jan Vijg, Andrei Seluanov, and Vera Gorbunova
  • Emergence of antiphage functions from random sequence libraries reveals mechanisms of gene birth (PNAS, October 15) by Idan Frumkin, Christopher N. Vassallo, Yi Hua Chen, and Michael T. Laub
  • How to upgrade stolen organelles into permanent plastids: A comparative transcriptomic perspective (PNAS, September 30) by Norico Yamada, Richard G. Dorrell, Ugo Cenci, Peter G. Kroth, Vincent Lombard, and Brittany N. Sprecher
  • Engineered geminivirus replicons enable rapid in planta directed evolution (Science, October 2) by Haocheng Zhu, Xu Qin, Leyan Wei, Dandan Jiang, Qiao Zhang, Wenqian Wang, Ronghong Liang, Rui Zhang, Kang Zhang, Guanwen Liu, Kevin Tianmeng Zhao, Kunling Chen, Jin-Long Qiu, and Caixia Gao,.

Physics and Chemistry

Information and Computation

Biological Self-Organization

Society

Brain and Cognition

Robotics and Artificial Life

Philosophy of Science

Just for Fun

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