Rule
1. Fire
Without controlled fire, no cooking, smelting, or large-scale land clearance.
Rule
2. Fine Manipulation
Hands, trunk tips, or analogues must grip, rotate, and apply pressure.
Rule
3. Social Learning & Long Lifespan
Skills must pass through generations for cumulative culture.
Rule
4. Symbolic Communication
Language or symbolic systems enable coordination and abstract planning.
Rule
5. Ecological Pressure
Intelligence is expensive; environments must reward problem-solving.
Rule
6. Niche Vacancy
No other civilization can already occupy the global builder niche.