Life has three stages, defined by what it can redesign

Tegmark frames all of life's history using a simple ladder. Life 1.0 (bacteria, most biology) can't redesign either its hardware (body) or software (behavior) within a lifetime — both are fixed by evolution across generations. Life 2.0 — humans — is stuck with evolution-given hardware, but can redesign its software: we learn languages, skills, and worldviews no ancestor could have downloaded into us.

Life 3.0 would be able to redesign both its hardware and software at will, escaping the multi-generational timescale of biological evolution entirely. No current organism has reached it, but sufficiently advanced AI could — able to rewrite its own code and, eventually, design its own physical substrate.

The framework matters because it reframes AI not as "a clever tool humans built" but as a potential new rung on life's ladder — one that could, if it arrives, evolve orders of magnitude faster than biological life ever could, since redesigning software takes seconds, not generations.