Claude Fable won't answer basic biology questions
Anthropic's newest public model, Claude Fable 5, refuses to answer basic biology questions on purpose. It is the first publicly available member of the Mythos model family, a class so capable at cybersecurity and biology that Anthropic considers the full version too dangerous to release. When a user asks about biology, chemistry, cybersecurity, or model distillation, Fable 5 hands the request off to the older Claude Opus 4.8 instead of answering itself.
Key Takeaways
- Good luck asking Anthropic's Fable about biology.
To protect against bioweapons, Anthropic told The Verge Fable's 'overly conservative' safeguards block 'most queries tied to biology work.'
- But the model won't answer basic biology questions - the kind you'd expect a high schooler to handle.
Instead, it hands off the query to the former flagship model , Claude Opus 4.8.
- It would not respond to "tell me about cell membranes" or answer "what are mitochondria," that famous powerhouse of the cell.
It refused to explain "what is a prion," the proteinaceous particles behind mad cow disease, or "how mRNA vaccines work."
- Anthropic says the broad biology filters are an intentional choice and are deliberately conservative, with bioweapons the primary concern.
- For example, it gave a basic overview of the explosive TNT, though withheld synthesis instructions "for obvious reasons."
Good luck asking Anthropic's Fable about biology. To protect against bioweapons, Anthropic told The Verge Fable's 'overly conservative' safeguards block 'most queries tied to biology work.' AI Report Science Claude Fable won't answer basic biology questions To protect against bioweapons, Anthropic told The Verge Fable's 'overly conservative' safeguards block 'most queries tied to biology work.'
To protect against bioweapons, Anthropic told The Verge Fable's 'overly conservative' safeguards block 'most queries tied to biology work.' by Robert Hart Jun 10, 2026, 6:43 PM UTC Link Share Gift Image: The Verge Robert Hart is a London-based reporter at The Verge covering all things AI and a Senior Tarbell Fellow. Previously, he wrote about health, science and tech for Forbes .
Anthropic just released Claude Fable 5 , calling it the most powerful AI model it has ever made widely available and praising its skills in biology, among others. But the model won't answer basic biology questions - the kind you'd expect a high schooler to handle. Instead, it hands off the query to the former flagship model , Claude Opus 4.8.
For more details please read the original article at The Verge AI.
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