What If Your AI Thinks Like a Brain? Welcome to Claude’s Secret Biology

Author(s): R. Thompson (PhD)

Originally published on Towards AI.

🚨 What if AI wasn’t just code — but alive, evolving, and thinking?

Artificial Intelligence has long remained an enigmatic ‘black box,’ intriguing yet opaque. However, Anthropic’s groundbreaking research, “On the Biology of a Large Language Model,” published on March 27, 2025, provides an unprecedented view into the computational biology of Claude 3.5 Haiku, a state-of-the-art lightweight language model. Using an innovative technique called Circuit Tracing, this study opens AI’s “black box,” revealing a startlingly intricate, lifelike system.

Anthropic’s researchers approached Claude like biologists examining cells under a microscope:

Circuit Tracing: replaces dense neural layers with interpretable “replacement models,” akin to cellular organelles.Dictionary Learning: identifies interpretable “features” (e.g., concepts like “Texas,” “Capital”) within Claude.Attribution Graphs: visually map interactions among these features, offering transparency into Claude’s reasoning process.

When Claude answers, “the capital of the state containing Dallas,” it internally performs complex, two-step reasoning:

Features identifying “Dallas” activate features tied to “Texas.”These “Texas” features then collaborate with “capital” features, yielding the answer “Austin.” 🧠

This process mimics neuronal signaling pathways — Claude effectively “thinks” through associations.

Claude doesn’t randomly rhyme — it meticulously plans:

Given: “He saw a carrot and had to grab it,” Claude pre-selects rhyme endings like “rabbit” and “habit” before composing the next line.Suppressing “rabbit” features… Read the full blog for free on Medium.

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Published via Towards AI