Dario Amodei

If scientists made versions of this biological material with the opposite handedness, and there are some potential advantages of these, such as medicines that last longer in the body, it could be extremely dangerous.

This is because left-handed life, if it were made in the form of complete organisms capable of reproduction, which would be very difficult, would potentially be indigestible to any of the systems that break down biological material on Earth.

It would have a key that wouldn't fit into the lock of any existing enzyme.

This would mean that it could proliferate in an uncontrollable way and crowd out all life on the planet, in the worst case even destroying all life on Earth.

There is substantial scientific uncertainty about both the creation and potential effects of mirror life.

The 2024 letter accompanied a report that concluded that mirror bacteria could plausibly be created in the next one to few decades, which is a wide range.

But a sufficiently powerful AI model, to be clear, far more capable than any we have today, might be able to discover how to create it much more rapidly, and actually help someone do so.

My view is that even though these are obscure risks, and might seem unlikely, the magnitude of the consequences is so large that they should be taken seriously as a first-class risk of AI systems.

Skeptics have raised a number of objections to the seriousness of these biological risks from VLLMs, which I disagree with but which are worth addressing.

Most fall into the category of not appreciating the exponential trajectory that the technology is on.

Back in 2023 when we first started talking about biological risks from LLMs, skeptics said that all the necessary information was available on Google and LLMs didn't add anything beyond this.

It was never true that Google could give you all the necessary information.

Genomes are freely available, but as I said above, certain key steps, as well as a huge amount of practical know-how.

cannot be gotten in that way.

But also, by the end of 2023 FLLMs were clearly providing information beyond what Google could give for some steps of the process.

After this, skeptics retreated to the objection that LLMs weren't end-to-end useful and couldn't help with bioweapons acquisition as opposed to just providing theoretical information.

As of mid-2025, our measurements show that LLMs may already be providing substantial uplift in several relevant areas, perhaps doubling or tripling the likelihood of success.

This led to us deciding that Claude Opus 4 and the subsequent Sonnet 4.5, Opus 4.1, and Opus 4.5 models needed to be released under our AI safety level 3 protections in our responsible scaling policy framework and to implementing safeguards against this risk, more on this later.

We believe that models are likely now approaching the point where, without safeguards, they could be useful in enabling someone with a STEM degree but not specifically a biology degree to go through the whole process of producing a bioweapon.

Another objection is that there are other actions unrelated to AI that society can take to block the production of bioweapons.