Primates with longer thumbs tend to have bigger brains, research finds | Evolution | The Guardian www.theguardian.com/science/2025...

Primates with longer thumbs tend to have bigger brains, research finds

Results suggest brain co-evolved with manual dexterity, say scientists, with humans by no means the outlier

theguardian.com

the other looking atastrocyte-derived signals (lab of @aleksandrapekowska.bsky.social) www.biorxiv.org/content/10.6...

Primate Astrocyte Evolution Controls the Tempo of Neuronal Development

Prolonged neuronal maturation, also referred to as neoteny, constitutes a hallmark of human brain evolution. Yet, the mechanisms controlling neotenic brain development remain poorly understood, and ha...

biorxiv.org

We examined how mammal ancestor brain size changed through the end-Permian extinction and found it barely changed! Brain evolution may have been put on hold for millions of years until ecosystems recovered. doi.org/10.1038/s415...

Evolutionary stasis in synapsid encephalization during the end-permian mass extinction - Scientific Reports

Scientific Reports - Evolutionary stasis in synapsid encephalization during the end-permian mass extinction

doi.org

Unlocking the early evolution of brain and feeding strategies in Anseriformes: the case of Conflicto antarcticus royalsocietypublishing.org/rsos/article...

Unlocking the early evolution of brain and feeding strategies in Anseriformes: the case of Conflicto antarcticus

Abstract. The early Palaeocene Conflicto antarcticus reveals a mosaic pattern of brain and skull evolution relative to other Anseriformes. Despite its hype

royalsocietypublishing.org

Unlocking the early evolution of brain and feeding strategies in Anseriformes: the case of Conflicto antarcticus: doi.org/10.1098/rsos... #RSOS #palaeontology #evolution

www.biorxiv.org/content/10.6... This looks really cool!

Cerebellar Purkinje cells change dendritic architecture during primate evolution

Vertebrate evolution has driven adaptive remodeling of brain regions impacted by changing sensorimotor demands. The cerebellum—a hindbrain area mediating associative learning and predictive coding—is ...

biorxiv.org

What next? More data are needed. Higher-resolution measures of calories & complexity: temperature, latitude, oxygen, predators, prey, competition and measures of brains beyond size. Data here: https://cephdata.com 12/

Thank you to my co-authors - PhD / postdoc leads Kiran Basava & Theiss Bendixen; lead RA Alexander Leonhard; fab RA team Nicole Lauren George, Zoé Vanhersecke, Joshua Omotosho, & my co-PI and cephalopod expert Jennifer Mather. Data & code: github.com/kcbasava/... 13/13

GitHub - kcbasava/ceph-brain-evolution

Contribute to kcbasava/ceph-brain-evolution development by creating an account on GitHub.

github.com

Brain data also only exists for 79 of ~820 living cephalopod species, and whole brain size misses lobe structure/neuron counts. The available species do span a wide range of sizes, habitats, & phylogeny, and sensitivity checks were consistent, but even so we don't have data for 90% of ceph. 11/

Important caveats: data and phylogenetically controlled models alone don't tell you the causal mechanism. That's why formal theory is useful - you can model assumptions and logic for possible mechanisms. A lot of the paper explains the role of theory in helping us interpret non-causal analyses. 10/

Sociality is the main difference b/w the ABH and SBH. SBH predicts more social species should have larger brains. Sociality was not reliably associated w/ larger brains - in fact perhaps the opposite. 9/

Depth also indicates shallower-living species tended to have larger brains. This fits the idea that shallower habitats are generally more calorie-rich, biodiverse, & more cognitively demanding than open-water habitats. Again, consistent w/ the ABH. 8/

Results: consistent w/ ABH, ecology predicted brain size. Sociality didn't. The strongest predictor was habitat: cephalopods living on or near the shallow seafloors had larger brains than open water species. The relationship was enormous, ~2/3 as large as the body-brain size relationship. 7/

The Asocial Brain Hypothesis says that while trial and error learning is less efficient than social learning, bigger brains can be favored when the environment is rich and complex enough that intelligence unlocks more calories & avoid predators. 5/

We preregistered the ABH predictions against the Social Brain & compiled the largest comparative brain dataset for cephalopods yet: 5 years 79 species 3,933 papers 115 variables coded a new phylogeny brain size, body size, ecology, sociality, & behavior 6/

Sociality can't explain cephalopod brain size, so what does? First, it's worth knowing that evolution favors the smallest brain that let's you survive and thrive, because brain tissue is expensive (about 20x as expensive as muscles in humans). So it has to be worth paying the energy bill 4/

Prior to the CBH, the dominant theory for the evolution of large brains was the social brain hypothesis - brains evolved to cope w/ the demands of group living. Cephalopods are smart - use tools, solve problems, deceive - but they're short-lived, die after reproducing, & even cannibalistic. 3/

Here we got around to testing this "Asocial Brain Hypothesis" in cephalopods - octopuses, squids, & cuttlefish - by spending half a decade building the most comprehensive database & test of their brain evolution yet. 2/ Paper: www.sciencedirect.co... Press release: www.lse.ac.uk/news/e...

Ecological not social factors explain brain size in cephalopods

Social factors have been argued to be the main selection pressure for the evolution of large brains and complex behavior, but many cephalopods live la…

sciencedirect.com

🚨 New paper in iScience: "Ecological not social factors explain brain size in cephalopods" In 2017, we published the Cultural Brain Hypothesis, a model of human brain evolution. It made an unexpected prediction: non-social animals could evolve big brains too, if their ecology was rich enough. 1/

New 🐟🧠 paper led by Olivia Carmstedt (not on Bluesky): Streaming for Fish. To understand how reciprocal social interactions affect brain development, we exposed guppies to either live conspecifics or video-recordings of fish. royalsocietypublishing.org/rsbl/article...

Streaming for fish? Screen-based social exposure disrupts brain development

Abstract. Social interactions form key developmental cues for plasticity in the vertebrate brain. However, few experimental studies disentangle specific as

royalsocietypublishing.org

Nature research paper: Whole-genome duplication shaped cell-type evolution in the vertebrate brain go.nature.com/4uyh9C1

Whole-genome duplication shaped cell-type evolution in the vertebrate brain - Nature

Analyses of brain single-cell transcriptomes from human, mouse, lizard, lamprey and amphioxus reveal that duplicated genes (ohnologues) played a pivotal part in early vertebrate cell-type diversification.

go.nature.com

Cats age like humans—could studying their brains reveal healthy aging secrets? phys.org/news/2026-06...

Cats age like humans—could studying their brains reveal healthy aging secrets?

Domestic cats age in remarkably similar ways to humans and show comparable age-related patterns of brain deterioration, according to an international collaboration among the University of Bath in the ...

phys.org

“We use geometric morphometry to reconstruct the most complete Homo naledi endocast & find a unique combination of ancestral & modern human-like characteristics: a derived frontal lobe but ancestral size, morphology & cerebrocerebellar proportions.” @dizachster.bsky.social @johnhawks.net in BS&F: 💀🧪

Brain structure and function in Homo naledi - Brain Structure and Function

Endocasts are casts of the internal surface of skull bones created by the brain and surrounding tissues. These fossil phantoms provide the most direct evidence of the brains of extinct organisms, and ...

link.springer.com

Revealing ancestral evolutionary patterns of the human brain at cell-type resolution, through comparative genomic analysis of open-chromatin regions across apes, old world monkeys & new world monkeys. New integrative paper from @konopkalab.bsky.social in @natcomms.nature.com. 🧠🧬🧪

Decoding DNA sequence-driven evolution of the human brain epigenome at cellular resolution - Nature Communications

How genetic changes prior to the human-chimpanzee split contributed to human brain evolution remains unknown. Here, the authors address this by identifying open-chromatin regions divergent in various ...

nature.com

Very cool new work on cortical folding, led by @r3rt0.bsky.social, showing the influence of the geometry of the the unfolded neocortex 🧪🧠 www.biorxiv.org/content/10.6...

Cortical folding patterns are encoded in the geometry of the unfolded neocortex.

Cortical folding patterns are conserved across individuals of gyrencephalic species and are closely related to cytoarchitectural organisation, connectivity, and function. Early morphogen gradients hav...

biorxiv.org

This study was supported by NIH funding and an excellent team of collaborators, including @fennak.bsky.social, @mallarinolab.bsky.social, @searslab.bsky.social, Mike DeBerardine, Aunoy Poddar, Miguel Turrero Garcia, and the Paredes, Harwell lab and Berke labs.

Collectively, the broad pattern of inhibitory neuron conservation suggests that, on the mammalian timescale, evolution modifies the brain by ‘teaching old cells new tricks’, rather than inventing novel cell types early in development.

Together, we conclude the TAC3 initial class is conserved across placental mammals, but modifies its gene expression and distribution throughout evolution.

In adult mouse, we identified a rare subpopulation of Th interneurons which expresses residual Tac2 (TAC3). Using the Allen institute’s Merscope data, we find this rare Tac2-expressing population is spatially restricted to the ventromedial striatum.