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Evolution sims

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jknilinux:
Hi everyone,

What is the usual outcome of an evosim? From reading other's posts, I get the feeling that bots end up regressing after "evolution", until they are unable to eat. Is there any way to escape this fate? Thank you!

EricL:
Hand coded bots generally "devolve" in an evo-sim, meaning the hand-authorred code stops functioning over time.  This is because all that hand-authorred DNA was written without context - it didn't evolve in conjuction with an ecosystem or under environmental or preditor or compitition induced selection pressures and thus when the bot is released into an evo-sim and subjected to mutations and selection, there is little or no selection pressure to preserve the DNA as written.  Selection is in operation to be sure and the bot is evolving, but selection is selecting for things that tend to break the fragile, hand-authored DNA - things like faster replication.   The DNA has to come down off that impossible peak in the fitness landscape before it can start it's slow journey back up the mountain.  Bascially, a hand-authorred bot is a super specialized, unrealistic aberation of nature, a boy in a bubble ill suited to survive in the "real world".

Zerobots or very very simple hand-authorred bots are a better starting poihnt for evo sims in that they don't have to fall off their peak first.  There, you generally see increases in functionality and complexity over time though I will be the first to admit we are still toying with excactly what is necessary w.r.t. selection pressures to provoke richer adaptions such as conditonal logic.

Numsgil:
Devolving to not eat isn't something that happens often (ever?).  Usually it's the other way around.  Bots evolve to eat everything, including their children.

Endy:
Is kind of a weird devolution then evolution that goes on. At first it can be depressing to watch the bots' population drop, but after awhile their population gradually climbs again. A simple hand authored bot is probably best, the bot I've been evolving has yet to die out after several days.

shvarz:
Another way to look at it is "survival of the flattest" (google it for more info). Basically, the hand-authored bot has very high fitness but the fitness peak is very narrow - most mutations break it down to non-functional state. Naturally evolving bot adapts not just to the environment but also to the mutation rate in the sim, so it evolves a simpler but more robust genome, which can tolerate many more mutations than the original one.

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