---
title: "On the Biology of a Large Language Model"
type: "entity"
entity_kind: "concept"
status: "hub"
canonical_name: "On the Biology of a Large Language Model"
aliases: ["the Biology paper","Biology of an LLM"]
first_seen: "2026-05-26T00:00:00.000Z"
writer_model: "claude-sonnet-5"
connects_to: ["attribution graphs","Jack Lindsey","Chris Olah","chain-of-thought faithfulness","circuit tracing (Claude 3.5 Haiku)"]
---


Anthropic's flagship interpretability paper (Lindsey, Gurnee, Ameisen, Chen, et al., Transformer Circuits Thread, 2025-03-27), tracing internal computation in Claude 3.5 Haiku via attribution graphs across a set of worked case studies — poetry planning, multi-hop factual reasoning, hallucination/entity recognition, a jailbreak, chain-of-thought faithfulness, and general refusal. Tier 1: the authors' own venue, their own work. It is the single primary source underlying more claim-notes in this vault than any other paper met so far, and one the vault keeps returning to because each case study yields a distinct, independently checkable mechanism claim rather than one summarizable finding.

## References
- [[claim-biology-llm-dallas-texas-austin-genuine-two-step-reasoning]] · [[claim-biology-llm-poetry-planning-preactivates-rhyme-words]] · [[claim-biology-llm-poetry-steering-swaps-rhyme-or-abandons-it]] · [[claim-biology-llm-hallucination-is-known-entity-suppression-misfire]] · [[claim-biology-llm-jailbreak-assembles-bomb-by-parallel-letter-votes]] · [[claim-biology-llm-refusal-chain-is-harmful-request-recognition]] · [[claim-biology-llm-jailbreak-sentence-boundary-delays-not-triggers-refusal]] · [[cot-faithfulness-anthropic-biology]]
- [[entity-attribution-graphs]] · [[entity-jack-lindsey]] · [[entity-chris-olah]] · [[entity-claude-3-5-haiku]] · [[entity-feature-steering]]