Can complexity come from simple rules?

Yes, and the demonstration is old enough to be unarguable. The interesting question stopped being whether simple rules can produce complexity decades ago. It is now: which complexity, how much, and can it keep going, or does it settle down and stop?

The part that is settled

Conway's Game of Life has four rules about how many neighbours a cell has. From them come gliders that travel, guns that emit gliders forever, and arrangements that perform arbitrary computation. None of that is written in the rules; all of it is a consequence of them.

That result generalises. Simple local interactions reliably produce large-scale structure in chemistry, in physics, in traffic, in markets and in flocks. If someone tells you complexity requires a designer, this is the observation that answers them, and it has been available since 1970.

The part that is not

Most such systems produce complexity and then stop. They reach a repeating pattern, or a frozen one, or a soup that keeps churning without ever building anything further. The open question in the field - open-ended evolution - is whether a system can keep producing genuinely new kinds of thing indefinitely, the way Earth's biosphere apparently has.

Nobody has built one that convincingly does. That is the honest state of the art, and projects claiming otherwise usually have a measure of novelty doing the work rather than the world.

What this project's rules are, and what came out of them

The rules here are not four, but they are simple in the sense that matters: nothing in them mentions the behaviours people find interesting. There is no rule about building, no rule about migration, no rule about cooperation, and no score.

What came out, in one universe over nine months of continuous running:

• Organisms moved roughly 45,000 units of ground from the interior of two islands into the sea at the southern edge, and closed the strait between them. The world's own generator had made two islands; the population made it one landmass, and the first crossing in its history happened on ground the population had put there.
• A fifth of the land it started with ended up under water, because digging below the waterline is irreversible and nothing was stopping it.
• An inherited movement direction reversed across the whole population in about fifty thousand ticks, by one family line replacing all the others.

None of those is in the rules. The full account is here, with the measurements and the pictures.

Why that is not proof of open-endedness

Striking behaviour from simple rules is the easy half, and this project is careful not to claim the hard half. One world, one seed, nine months. Whether it keeps producing genuinely new kinds of thing, or whether it has already done the interesting part and will now repeat itself for years, is not something nine months can answer.

That is why the world is still running and the record is permanent rather than summarised.

What emergence means precisely · Cellular automata · Watch the rules running