Bots and Simulations > Evolution and Internet Sharing Sims

South Pacific Sim

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EricL:
Looking for stress and stability bugs in 2.42.1, I needed to construct long running sims (> 1M cycles) at the largest field size where I could have complex bots with lots of mutation evolve indefintly without runaway selection or other short-sighted adaptations causing the entire sim to go extict - a common occurance in some of my previous evo sims where bots evolved to kill off all the plants or became canibalistic, forgot about plants, and killed each other off.

I also wanted to try to keep the bot population somewhere around 1000 or so; low enough to keep things moving fast and not bump up against the artificial 5000 bot limit but high enough to get some real population variation and mutation in different directions.  Additionally, I wanted population isloation.  That is, to set up an evironment where speciation would occur.  I wanted enough isolation that it was difficult, but not impossible for bots to migrate from one local ecosystem to another without using walls.

The solution was to create a veggy "chain of islands" not unlike the Pacific Ocean Island chain.  What I did was use a small number of very high energy, stable, fixed veggies - no more than 25 or so for the largest sim size and strung them out across the screen.  Each "island" provided essentially infinite food, but physical access to that resoruce is limited by space.  Each island is far out of sight form the other, so bots have to balance staying put and competing for a limited resource versus venturing out into the blue and taking their chances on finding a new undiscoverred resourse in some random direction.

I wanted to favor DNA complexity, so I removed all the costs on DNA operations so that having a longer DNA or executing more genes is not in and of itself disdvantageous.  But I had to tax something to provide selective pressure so there is a body upkeep cost of 0.1 per cycle as well as costs on things like venom and shell.  This way, DNA complexity can evolve and selection favors action effeciency.  They have to eat, they to have to find food and compete for limited resources or they will die.  The genes they use to do that can be as many or as complex as they need.  Generally a bot with typical energy can live long enough to reach the next island if they happened to set out in the right direction, but if they didn't, leaving your island tends to be fatal.

The limited number of veggy islands, the restrictiosn in physical access to these resources and the body upkeep cost tends to keep the population between 1000 and 15000, about where I want it.  (I actually had to increase the body upkeep cost over the first few 100,000 cycles as bots got more effecient.)  Sometimes a population spike or fall off will occur as a bot evolves cannabalistic tendencies or some other new short term strategy that gives individuals massive advantage in the short term, but if such an adaptaion is disadvantagous for the species and ecosystem (will leads to extinction relatively quickly) it won't spread to all the islands due to the time and cost it takes to do so.  Island populations can go extict, but they get resettled eventually by populations from surviving islands which did not develop the fatal adaptation.   Thus, the sim as a whole never seems to die.  Things change, sub species change and evolve, and go extinct, but the sim as a whole lives on.

The Settings file is attached.  I'd attach the sim, but even zipped, its 818k...

-Eric

Numsgil:
Nice idea, I think that's how other Alife sims tend to tackle similar problems.  As long as you're shuffling the island populations from time to time it should help keep the bots from suiciding.

PurpleYouko:
Did you try running this in zero-momentum mode?
I have been getting good results when trying to restrict movement by doing that lately.

BTW. Where do I get the robots? They aren't in the zip.



Hey Num!

What's the deal with the monkey?

EricL:

--- Quote ---Did you try running this in zero-momentum mode?
--- End quote ---

I have not.  I may try that next.  As it is though, it's sufficiently difficult for bots to migrate between islands that each evolves it's own little local sub-species.  I can actually zoom out and see that each islands has it's own unique color of surrounding bots, where the colors of islands in close proximity are more similar than those far apart!  Way way cool.


--- Quote ---Hey Num!

What's the deal with the monkey?
--- End quote ---

He went extinct.  His avatar got populated from an adjacent island.  

Griz:
no doubt I'll have to decrease the field size.
I'll try to compensate by scaling down the pop of veggies and starting bots
and see if it's still works and is interesting.

I'm always tring to find was of isolating populations ...
using gravity and selective placement windows for veggies up hgh
or along one edge.
I wonder if it possible to have mulitple placement windows for veggies?
I've tried having more than one species of veggie ...
but seems the prog ends up only doing repop events for one of them.

ok
more ideas to play with.

Eric ...
are you retired, independantly wealthy with time on your hands ...
or do you do all this in you 'spare' time.
hmmmm ....
or perhaps locked up somewhere in a correctional facility with
only a computer and internet connection.

whatever ...
glad you're doing it.

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