Fernando Garcia-Moreno

Comparative neuroscience is not about abandoning models.
It is about putting them back into evolutionary context.
That conversation will be central at 𝗖𝗼𝗿𝘁𝗶𝗰𝗮𝗹 𝗘𝘃𝗼𝗹𝘂𝘁𝗶𝗼𝗻 𝟮𝟬𝟮𝟲.
𝗕𝗶𝗹𝗯𝗮𝗼 · 𝗝𝘂𝗻𝗲 𝟭𝟱–𝟭𝟳
#CorticalEvolution2026

an aerial view of a coastline with a large body of water in the background ALT: an aerial view of a coastline with a large body of water in the background

By focusing mostly on rodents, we risk redefining complexity as noise —
and overlooking developmental constraints, scaling problems, and circuit specializations that only appear in other lineages.
To see principles, we need evolutionary distance.
#CorticalEvolution2026

Rodents are extraordinary experimental systems.
But they are not heavy users of the cortex.
Their cortex is small, smooth, and solves a different computational problem than in many other mammals.
Sometimes simplicity hides biology rather than revealing it.
#CorticalEvolution2026

A comment on my previous thread jokingly noted that our “diverse” mammalian models mostly belong to the same branch: 𝘌𝘶𝘢𝘳𝘤𝘩𝘰𝘯𝘵𝘰𝘨𝘭𝘪𝘳𝘦𝘴.
Mouse, rat… and primates are closer relatives than we often like to admit.
So — 𝗵𝗮𝘃𝗲 𝘄𝗲 𝗯𝗲𝗰𝗼𝗺𝗲 𝘁𝗼𝗼 𝗺𝗼𝘂𝘀𝗲-𝗰𝗲𝗻𝘁𝗿𝗶𝗰?
#CorticalEvolution2026

that's true, more specific 😉

Cortical evolution is hard because it sits at the intersection of:
developmental biology
systems neuroscience
genomics
comparative anatomy
𝗧𝗵𝗮𝘁 𝗶𝗻𝘁𝗲𝗿𝘀𝗲𝗰𝘁𝗶𝗼𝗻 𝗶𝘀 𝗲𝘅𝗮𝗰𝘁𝗹𝘆 𝘄𝗵𝗲𝗿𝗲 #𝗖𝗼𝗿𝘁𝗶𝗰𝗮𝗹𝗘𝘃𝗼𝗹𝘂𝘁𝗶𝗼𝗻𝟮𝟬𝟮𝟲 𝘄𝗶𝗹𝗹 𝗳𝗼𝗰𝘂𝘀
Come join our conference! Bilbao, June 15-17 2026

a hamster is standing on its hind legs and looking at the camera . ALT: a hamster is standing on its hind legs and looking at the camera .

Third, 𝘄𝗲 𝗮𝗿𝗲 𝗯𝗶𝗮𝘀𝗲𝗱 𝗯𝘆 𝗼𝘂𝗿 𝗺𝗼𝗱𝗲𝗹 𝘀𝘆𝘀𝘁𝗲𝗺𝘀.
Much of what we call “fundamental” may simply reflect rodent biology.
Comparative neurobiology forces us to re-evaluate what is truly conserved, 𝘧𝘶𝘯𝘥𝘢𝘮𝘦𝘯𝘵𝘢𝘭.
#CorticalEvolution2026

Second, ᴅᴇᴠᴇʟᴏᴘᴍᴇɴᴛ ᴀɴᴅ ᴇᴠᴏʟᴜᴛɪᴏɴ ᴀʀᴇ ɪɴꜱᴇᴘᴀʀᴀʙʟᴇ ⛓️.
Small changes in progenitor behavior, timing, or lineage relationships can scale into large architectural differences.
The difficulty is linking molecular changes to macroscopic structure.

First, the cortex changes along multiple axes at once:
size, folding, cell-type diversity, connectivity, developmental timing.
𝙉𝙤 𝙨𝙞𝙣𝙜𝙡𝙚 𝙫𝙖𝙧𝙞𝙖𝙗𝙡𝙚 𝙚𝙭𝙥𝙡𝙖𝙞𝙣𝙨 𝙩𝙝𝙚 𝙤𝙩𝙝𝙚𝙧𝙨.
Expansion alone is not the answer.
#CorticalEvolution2026

𝗨𝗻𝗱𝗲𝗿𝘀𝘁𝗮𝗻𝗱𝗶𝗻𝗴 𝗰𝗼𝗿𝘁𝗶𝗰𝗮𝗹 𝗲𝘃𝗼𝗹𝘂𝘁𝗶𝗼𝗻 sounds straightforward:
compare species, identify differences, explain them.
In reality, it 𝗶𝘀 𝗼𝗻𝗲 𝗼𝗳 𝘁𝗵𝗲 𝗵𝗮𝗿𝗱𝗲𝘀𝘁 𝗽𝗿𝗼𝗯𝗹𝗲𝗺𝘀 𝗶𝗻 𝗻𝗲𝘂𝗿𝗼𝘀𝗰𝗶𝗲𝗻𝗰𝗲.
𝘞𝘩𝘺?
#CorticalEvolution2026

Ready to see the big picture of how the vertebrate brain balances stability with change? 📖 Check out the full chapter in Evolution of Nervous Systems here :https://shop.elsevier.com/books/evolution-of-nervous-systems/kaas/978-0-443-27380-3

a drawing of a lizard with green spots on its body ALT: a drawing of a lizard with green spots on its body

This deep dive was a huge team effort! ✍️ Huge congrats to co-authors: Sᴀʀᴀ Jɪᴍéɴᴇᴢ and Tᴀᴛɪᴀɴᴀ Gᴀʟʟᴇɢᴏ-Fʟᴏʀᴇꜱ
@AchucarroGlia
👏👏

𝗛𝗼𝘄 𝗱𝗼 𝘄𝗲 𝘁𝗿𝗮𝗰𝗸 𝗰𝗵𝗮𝗻𝗴𝗲𝘀 𝗳𝗿𝗼𝗺 𝟯𝟬𝟬 𝗺𝗶𝗹𝗹𝗶𝗼𝗻 𝘆𝗲𝗮𝗿𝘀 𝗮𝗴𝗼? 🕵️‍♂️ Molecular detective work! We discuss the use of scRNA-seq (reading single-cell genetic diaries) to see how similar neurons hide under different disguises across species. 🧬🔬

But it’s not just the tectum! We explore how the 𝘁𝗵𝗮𝗹𝗮𝗺𝘂𝘀 and 𝗽𝗮𝗹𝗹𝗶𝘂𝗺 (the precursor to the cortex) talk to each other. Even in "simpler" brains, these connections are incredibly sophisticated, proving that complex vision isn't just a mammal thing. 🧠🔗

The 𝗼𝗽𝘁𝗶𝗰 𝘁𝗲𝗰𝘁𝘂𝗺 is the star of the show for many vertebrates. 🌟 In reptiles and birds, it’s a complex, layered processing hub. We break down the developmental mechanisms that build this structure and why it's so vital for survival in the wild. 🐍🦅

Evolution loves a good remix. While the core visual territories are the same, different animals prioritize different visual routes. Mammals went all-in on the lemnothalamic route for high-def detail, while reptiles and birds doubled down on the collothalamic pathway for speed. ⚡️

Ever heard of the 𝙥𝙝𝙮𝙡𝙤𝙩𝙮𝙥𝙞𝙘 𝙗𝙧𝙖𝙞𝙣? 🧬 Basically, all vertebrates start with a shared embryonic blueprint that hasn’t changed in millions of years. We look at how early-born neurons act as the "foundational crew" before species-specific features even show up. 🏗️🧱

Hᴏᴡ ᴅᴏ ʏᴏᴜ ʙᴜɪʟᴅ ᴀ ʙʀᴀɪɴ ᴛʜᴀᴛ ᴄᴀɴ ᴄᴏɴqᴜᴇʀ ʟᴀɴᴅ, ᴀɪʀ, ᴀɴᴅ ꜱᴇᴀ? 🧠 It’s not just about adding new parts; it’s about "tinkering" with what’s already there! Our new review dives into Evo-Devo and how small developmental tweaks create many brain forms🦎🐦

𝗧𝗵𝗶𝘀 𝗶𝘀 𝘄𝗵𝘆 𝘄𝗲 𝗮𝗿𝗲 𝗼𝗿𝗴𝗮𝗻𝗶𝘇𝗶𝗻𝗴 𝗖𝗼𝗿𝘁𝗶𝗰𝗮𝗹 𝗘𝘃𝗼𝗹𝘂𝘁𝗶𝗼𝗻 𝟮𝟬𝟮𝟲 𝗶𝗻 𝗕𝗶𝗹𝗯𝗮𝗼.
To bring together evolutionary, developmental and systems perspectives and to rethink where the field is going next.
June 15–17, 2026 Spain
#CorticalEvolution2026

Importantly, cortical evolution is not just about the past.
Many vulnerabilities of the human brain, from developmental disorders to psychiatric disease, may be inseparable from the evolutionary trajectories that shaped cortical expansion and complexity.

𝗘𝘃𝗼𝗹𝘂𝘁𝗶𝗼𝗻 𝗽𝗿𝗼𝘃𝗶𝗱𝗲𝘀 𝘁𝗵𝗲 𝗺𝗶𝘀𝘀𝗶𝗻𝗴 𝗱𝗶𝗺𝗲𝗻𝘀𝗶𝗼𝗻.
Only by comparing species can we distinguish what is conserved from what is derived, what is fundamental from what is contingent, and which features come with hidden costs.
#CorticalEvolution2026

We now describe the cortex in extraordinary detail:
cell types, layers, gene expression, developmental programs.
Yet description alone doesn’t explain why the cortex is built the way it is — or why evolution took such different paths in different lineages.
#CorticalEvolution2026

𝗪𝗵𝘆 𝘁𝗮𝗹𝗸 𝗮𝗯𝗼𝘂𝘁 𝗰𝗼𝗿𝘁𝗶𝗰𝗮𝗹 𝗲𝘃𝗼𝗹𝘂𝘁𝗶𝗼𝗻 𝗻𝗼𝘄?
Because many of the biggest open questions in neuroscience still revolve around the cerebral cortex — how it emerged, expanded, diversified, and why it differs so much across species.
#CorticalEvolution2026

Many thanks Feline!! Great you liked it!
I am convinced the same principles apply to other vertebrate species but have no data to support it. Indeed, the rules might be easier to detect, in species with a far smaller cortex

Thanks man, I do love receiving this GIF

Gracias Diego!!!

Connectivity of the adult human brain with sequential neurogenesis of circuits and transcriptomics signatures - Nature Communications Understanding the architectural principles shape human brain networks is a major challenge for systems neuroscience. Here, authors show embryogenic age is associated with functional and structural bra...

📄 Nature Communications (2026)
doi.org/10.1038/s414...
Fantastic work by Ibai Diez, Nayara Carral-Sainz, Sebastiano Stramaglia, Alicia Nieto-Reyes, Mauro D’Amato, Jesús M Cortes & led by fantastic Paolo Bonifazi!
@achucarro.bsky.social @cicbiogune.bsky.social bioBizkaia; Ikerbasque

Together, these rules link 𝘀𝗲𝗾𝘂𝗲𝗻𝘁𝗶𝗮𝗹 𝗻𝗲𝘂𝗿𝗼𝗴𝗲𝗻𝗲𝘀𝗶𝘀 to 𝗮𝗱𝘂𝗹𝘁 𝘀𝘁𝗿𝘂𝗰𝘁𝘂𝗿𝗮𝗹 𝗮𝗻𝗱 𝗳𝘂𝗻𝗰𝘁𝗶𝗼𝗻𝗮𝗹 𝗯𝗿𝗮𝗶𝗻 𝗻𝗲𝘁𝘄𝗼𝗿𝗸𝘀, providing a unifying developmental principle.

Rule 2 — 𝓟𝓡𝓔𝓕𝓔𝓡𝓔𝓝𝓣𝓘𝓐𝓛 𝓐𝓖𝓔 𝓐𝓣𝓣𝓐𝓒𝓗𝓜𝓔𝓝𝓣
Brain circuits born around the same developmental time preferentially connect to each other.
𝗡𝗲𝘂𝗿𝗼𝗻𝘀 𝘁𝗲𝗻𝗱 𝘁𝗼 “𝗵𝗮𝗻𝗴 𝗼𝘂𝘁” 𝘄𝗶𝘁𝗵 𝘁𝗵𝗲𝗶𝗿 𝗴𝗲𝗻-𝗺𝗮𝘁𝗲𝘀.

Rule 1 — 𝒪ℒ𝒟ℰℛ 𝒢ℰ𝒯𝒮 ℛℐ𝒞ℋℰℛ
Neuronal circuits that develop earlier become more central in the adult brain network.
They form longer-range, more abundant connections and act as ᴇᴀʀʟʏ ᴄᴏʟᴏɴɪꜱᴇʀꜱ of the growing connectome.