The loop
One generation, slowed to its three beats: score every design against the objective, select — the unfit fade, the fit stay — and breed, each survivor spawning children that are copies plus a wobble of mutation. That’s the whole algorithm. Everything else is consequences.
Step through the beats and watch one generation turn.
The cloud climbs
Run the loop and the population behaves like a creature: it drifts uphill, pools in basins, and pours itself onto the best peak it has found — because selection is a channel through which one lucky discovery becomes everyone’s starting point. One climber succeeded a quarter of the time here; the crowd almost always does.
Watch best and average fitness rise together.
The mutation dial
This landscape hides its true summit — a narrow spike on the flank of a broad, seductive hill. Turn mutation down and the population commits early, freezing on the big hill before anyone stumbles onto the spike. Turn it up to a healthy wobble and the cloud keeps enough restlessness to find it. Turn it to a boil and the cloud never settles at all — its best find is a lottery ticket, not a design language.
Try all three temperaments on the same trap.
Crossover assembles
Mutation only wobbles; crossover recombines — a child takes some genes from each parent. On problems whose answers have separable parts, that’s a superpower: one parent has solved the ridge in x, another the ridge in y, and one of their children inherits both halves and lands where neither parent could reach. Evolution doesn’t just search; it assembles partial solutions.
Breed the two specialists and watch a child hit the crossing.
Evolve the tower
The payoff: evolution as a designer. A population of twenty-four towers — the four-parameter vector from the start of this part is now a genome — bred against an objective you choose. Watch the family portrait converge generation by generation: score for floor area and slabs take over the gene pool; efficiency breeds mid-rises; slenderness breeds spires. The champion stands on the right. Nobody drew it.