Imagine a circle. Now put a smaller circle inside it. Add a few squiggles between them, like someone tried to fold a fitted sheet and the sheet developed opinions. You are surprisingly close to the problem this new paper tackles: how different carnivores pack a lot of cortex into a finite skull, and why the wrinkles do not look the same from species to species.

The paper by Boch and colleagues is a cartography project for carnivore brains, except the map is made of grooves, ridges, and a heroic amount of patience. Using mostly post-mortem MRI scans from 26 species across eight carnivore families, the team reconstructed cortical surfaces and labeled the major sulci - the grooves on the neocortex - to build the largest comparative carnivoran brain collection of its kind [1].

That matters because dogs, cats, bears, mongooses, seals, and their relatives solve very different ecological problems. Some stalk alone. Some hunt socially. Some manipulate the world with nimble forepaws. Some seem built to hear a snack rustle from three zip codes away. If the cortex helps handle those lifestyles, you would expect the surface anatomy to show some of that history.

And it does, at least in suggestive ways. The authors found that arctoid species with more dexterous forepaws tended to have more elaborate sulcal patterns in the presumed somatosensory cortex, which is exactly where you would want extra neural real estate if your paws are doing more than decorative fluff work [1]. Canids stood out for having the largest number of unique major sulci, including an occipital sulcus not seen as broadly elsewhere, and highly social canids had an extra frontal sulcus. Meanwhile, cats and dogs differed in the complexity of occipitotemporal sulci, a region tied to visual and auditory processing [1].

Not Just Bigger Brains, Different Blueprints

One nice thing about this study is that it pushes past the usual "which animal has the bigger brain?" bar fight. Brain size matters, but it is a blunt instrument. A folded cortex is not just a larger towel stuffed into a cabinet. It is a surface shaped by development, mechanics, and evolutionary tinkering.

Recent reviews make that point clearly. Cortical folding seems to arise from a mash-up of cell biology and physics: neural progenitors expand the cortical sheet, mechanical stress helps it buckle into folds, and species-specific growth patterns tune the final shape [2,3]. A 2025 comparative eLife study went further, showing that differential growth and starting geometry can reproduce strikingly different folding patterns across species [4].

So when Boch and colleagues describe different sulcal "recipes" across carnivores, they are not just cataloging grooves for the love of grooves. They are capturing the visible record of developmental choices.

What This Might Mean Outside the Anatomy Lab

If these patterns hold up, this atlas could help in three ways. First, it gives researchers a better comparative framework. If you want to compare brain organization across species, you need landmarks that mean the same thing across maps.

Second, it may sharpen links between behavior and brain layout. A 2023 review on carnivoran ecomorphology argues that ecology leaves reliable fingerprints on anatomy across this order [5]. This paper extends that idea into the neocortex. Not proof that "social hunting creates this sulcus" or "clever paws produce that groove" - science is rarely that tidy - but at least a way to ask the question without hand-waving.

Third, folds may do more than pack tissue efficiently. A 2024 Nature Communications study suggested sulci could also improve glymphatic circulation, the fluid-cleanup system that helps clear waste from the brain [6]. So the grooves may not be mere origami. They may also help with plumbing.

The Honest Caveat, Because the Brain Loves Humbling Us

This is still a foundational anatomy study, not a final verdict on carnivore cognition. The sample spans many species, but not many individuals per species, so within-species variation remains hard to pin down. And while the ecological interpretations are plausible, they are not the same as direct functional proof [1]. Fair enough. You do not build the whole cathedral in one afternoon. First you figure out where the doors are.

Still, there is something wonderfully human about this whole enterprise. We look at a dog, a fox, a bear, a seal, and a cat, and ask whether their ways of moving through the world left signatures on the folds of the cortex. The answer, increasingly, seems to be yes - in the careful, slightly fussy, scientifically responsible sense of yes. Which is less cinematic than a movie montage, but much more useful.

References

1. Boch M, Karadachka K, Loh KK, et al. Between-species variation in neocortical sulcal anatomy of the carnivoran brain. eLife. 2025. DOI: 10.7554/eLife.100851. PubMed: PMID 41528121
2. Akula SK, Exposito-Alonso D, Walsh CA. Shaping the brain: The emergence of cortical structure and folding. Developmental Cell. 2023;58(24):2836-2849. DOI: 10.1016/j.devcel.2023.11.004. PMCID: PMC10793202
3. Garcia KE, Kroenke CD, Bayly PV. Mechanical stress connects cortical folding to fiber organization in the developing brain. Trends in Neurosciences. 2025;48(6):395-402. DOI: 10.1016/j.tins.2025.04.001. PMCID: PMC12439404
4. Yin S, Liu C, Choi GPT, et al. Morphogenesis and morphometry of brain folding patterns across species. eLife. 2025;14:RP107138. DOI: 10.7554/eLife.107138. PMCID: PMC12747518
5. Schwab JA, Figueirido B, Martin-Serra A, et al. Evolutionary ecomorphology for the twenty-first century: examples from mammalian carnivores. Proceedings of the Royal Society B. 2023;290(2011):20231400. DOI: 10.1098/rspb.2023.1400. PMCID: PMC10685142
6. Kameya N, Sakai I, Saito K, et al. Evolutionary changes leading to efficient glymphatic circulation in the mammalian brain. Nature Communications. 2024;15(1):10048. DOI: 10.1038/s41467-024-54372-1. PMCID: PMC11618516

Disclaimer: The image accompanying this article is for illustrative purposes only and does not depict actual experimental results, data, or biological mechanisms.