hal@finney.org writes:
> I think Robin is referring here not to raw materials, but to processed
> materials ready to be turned into finished product. This feeds into
Then the "growing" rate refers to how long it takes to turn all
locally available matter into life. While this might enrichen and
separate elements, it would not actually be wise for an unauthorized
seed to enter such a system (these maser and laser beams are pretty
bright). Plus, even stealthy pioneer seeds would not have much chance
in a mature ecology.
> the question of how quickly the replicators could build new seeds and
> launchers.
>
> My feeling is that once the wave has passed you by, evolution is through
> with you. All the factors that got you here are irrelevant now.
No, the evolution is still pretty much active. Only the fitness
function has changed: you don't get benefit for running anymore. Now
the question is whether you now 1) metamorphize into sedentary
phenotype (I agree with you that there there is not much need for a
pioneer to carry such genotype) 2) adapt rapidly to changed conditions
3) failing that, get overwhelmed by slower but fitter successor wave
organisms (that wave did come from somewhere, after all).
> It is very analogous to an organism which has lived past the age at
> which it can reproduce. Selection pressures no longer act to keep such
> organisms alive, for exactly the same reason.
Why? The critters are still alive. They can still replicate, and
they'll run into limited resources. Using our infinite agar plate
metaphor, assume slowly growing agar (continuation of life-supporting
conditions). After the wave front specialists have passed, the medium
is left colonized. Now you will to start adapting to sedentary
conditions, evolve into grass, sheep, wolves, people with guns and
whatever evolution nonlinearities will come up with.
> In other words, if the fastest way to expand is to build fast in some
> kind of catastrohic mode which will kill the organisms which stay behind,
> that is what will evolve (eventually). If the fastest way to expand
> happens to leave organisms behind, then that is instead what will evolve.
I don't see the logic behind such reasoning, and I don't see instances
of such behaviour in terran ecology. Pioneer organisms are always
displaced by successors, not due to apoptosis. Suicide at cell and
individuum level is rare, and never total.
> Selection/evolution plays no part in determining the fate of colonies
> which have fallen behind the wave. Their behavior is unselected-for.
> There is no selection pressure to favor colonies which hold onto the
> systems after launching seeds (once the frontier has become unreachable).
No. There is no selection pressure to continue launching the seeds,
because the wave front has passed. Now launching the seeds reduces
your fitness, since removing resources from growth and competition.
> > Staying is default. The launchers can't launch themselves, so they
> > stay. Sustainable barrage of stellar neighbours with seeds is a waste
> > of resources after they're infected, so they'll cease.
>
> The behavior of the launchers after the frontier has become unreachable
> has no effect on the rate of spread of the frontier, hence this kind of
> reasoning cannot play a role in the selection of the fastest-spreading
> replicators.
Sure, but I never claimed it did. I'm describing the behaviour of
post-wave organisms who adapt to a changed fitness function. This does
not impact the wave front organisms.
> Sterility is a possibility, but many other behaviors are possible as well.
Expecting sterile substrate (or even sterile organisms) in wave's wake
is utterly unreasonable. Life just doesn't do such things.
This archive was generated by hypermail 2b30 : Mon May 28 2001 - 09:50:17 MDT