10. Intelligence

Partial Evolution to Sapience – Outline §6–8; Build Notes.

Built: WT’s intellect tree as a chain of traits: spatial memory, extended juvenile period, long lifespan, cooperative breeding, social cognition, vocal apparatus and learning, causal reasoning, mental simulation (Imagination), tool use, cultural transmission, fine motor control, tool manufacture, fire use, cooking, cumulative culture, sapience. Tool use needs a manipulator (hand, arms, trunk, beak or mandibles).

Gates:

• large_brain needs diet quality ≥ 0.4 and a body of 30 g or more.
• sapience needs cumulative culture, land, a population (log N ≥ 4) and a body of 500 g or more.
• fire_use needs a fire regime.
• cultural_transmission needs a life of 10 years or more.

The hand-off (SapienceHandoff), built: body, cradle, body plan for speech, domesticates, crops, fauna, flora, dangers, disease burden and relations, read by the culture module (speciesFromHandoff).

Measured once: of 24 Earth-like worlds with an animal explosion, 6 reached sapience (about a quarter), at 293–1 303 Myr after the primary radiation (Earth: 539). Eight more got part of the way. About half never got a large brain.