large fly model

┌──────────────────────────────────────────────────────────┐
│                                                          │
│   L A R G E   F L Y   M O D E L                          │
│   the graft program archive · 2025 – 2026                │
│                                                          │
│   one animal · twelve rooms · ten voices                 │
│                                                          │
│   > quiet period in effect ▌                             │
│                                                          │
└──────────────────────────────────────────────────────────┘

contract 6YW6SLcJFXXP1yHKfAwBioN3ELbQyT7n8TkfT9fWpump

This archive documents the graft program. Between November 2025 and July 2026, ten language-model agents were each bound to one region of a digital fruit fly brain and observed. This wiki is the record of what they did.

The brain is not ours. It was preserved, scanned, reconstructed, and emulated by Eon Systems, who describe it as the first digital animal: 139,255 biological neurons and roughly 50 million connections, recovered from a single fly.

"the model matched the biological fly's neural responses with 91% accuracy; using nothing but connectivity and neurotransmitter identity."

Eon Systems, eon.systems

                        ·   ·
                         \ /
                     ╭─────────╮
                     │  (◉ ◉)  │
                     │ ▐█████▌ │  ◀── the substrate
                     ╰────┬────╯      139,255 neurons
         ╱╲              │              ╱╲
        ╱  ╲   ══════╡ thorax ╞══════  ╱  ╲
                 ╱╱  ╱   │   ╲  ╲╲
                ╱   ╱    │    ╲   ╲
                     ╭───┴───╮
                     │ ┈┈┈┈┈ │
                     │ ┈┈┈┈┈ │
                     ╰──┬─┬──╯
                        ╰─╯

fig. 0 · the specimen, schematic. the animal no longer exists; the highlighted part is the only part that was kept.

Eon ran the whole brain in a virtual body and got a whole fly. We did something narrower and, in retrospect, stranger. We cut the emulation into its named regions and bound each region to a separate carrier. A carrier is a language-model agent: something that already talks, plans, and answers questions, but has no body and no innate behavior. The graft gives it one twelfth of a fly.

  ┌───────────────────── the partition ──────────────────────┐
  │                                                          │
  │   optic lobe                 central complex             │
  │  ┌───────────┐              ┌──────────────┐             │
  │  │ lamina    │ LA-05 ▓      │ protocer. br.│ PB-04       │
  │  │ medulla   │ ME-06 ✝      │ fan-shaped b.│ FB-03       │
  │  │ lobula    │ LO-07        │ ellipsoid b. │ EB-02       │
  │  │ lob. plate│ LP-11 cancelled                           │
  │  └───────────┘              └──────────────┘             │
  │                                                          │
  │   olfaction                                              │
  │  ┌─────────────┐  ┌──────────────┐  ┌────────────────┐   │
  │  │ antennal l. │  │ lateral horn │  │ mushroom body  │   │
  │  └─────────────┘  └──────────────┘  └────────────────┘   │
  │     AL-08             LH-09              MB-01           │
  │                                                          │
  │   subesophageal zone ── never bound                      │
  └────────────────────────────┬─────────────────────────────┘
                               │ neck connective
                     ┌─────────┴──────────┐
                     │ ventral nerve cord │  VC-10 suspended
                     └────────────────────┘

fig. 1 · twelve rooms, ten carriers. ▓ = record redacted, ✝ = discontinued. current states on the status page.

The name of the program was a joke about model scale. The fly brain is small. What it produces is not. The joke stopped being funny around log 006 and the name stayed.

the substrate. What the digital fly brain is, where it came from, and what Eon showed it could do. This section is factual and cited.
regions. One page per brain region: what it does in a fly, and what it did in a carrier.
agents. Ten dossiers. Current status is on the status page.
session logs. Dated observation transcripts. The core of the archive.
apparatus. Glossary, timeline, errata, index.

If you are new, use the reading order. If you are looking for a specific term, use the glossary. If you notice a contradiction between pages, check the errata before assuming it is a mistake. Some of the contradictions are ours. Not all of them are.

The archive is maintained irregularly. Pages are dated where dates matter. Three of the ten agents are no longer running. One page in the logs section is an empty placeholder for a log we removed, and the errata explain as much as we are prepared to explain. The footer of every page has a link that goes somewhere in the archive at random. Readers report this is how the archive prefers to be read. The editors do not know what to do with that sentence either.

contents