I think Walter Wayne was saying that it is like a drunkard's walk, the whole trajectory is random, but depends on the past history.
I get that. In the same way that the density or temperature of a gas is non-random so is the sum of the dice. Even though each particle may be in a random walk or each die may be behaving randomly. Density is actually an exact analogy, it is the integral(sum) over the energy distribution.
<nitpick>some smoke detectors do produce an oputput that is a "level of smoke" which is returned to the controller, wheich then assesses whether the whol system is indicitive of a dangerous fire or a false alarm. For example ambient pollution, or cigarette smoke. In the industry, these are termed smoke "sensors" rather than "detctors" which do only have an alarm/non-alarm output, I have previously worked in (in the fire "detector" and "sensor" development area). </nitpick>
It doesn't really matter if some are. The smoke detector is a counter example, thus there only need to exist one smoke detector that has binary output to prove the point. You might as well have said that it could be a spark plug. It wouldn't make a difference to the logic of the point.
I have said that in a stable environment, and over a long enough time, then you don't need to invoke randomness. This does cover a lot of examples used when discussing how evolution works, for example the advantage of sight.
I would still argue that the particular adaptations could still be random, e.g. compound eye vs simple eye, position of the retina etc... but the adaptation to the environment would be there.
However this stable environment is only a subset of the situations where evoution occurs, even if it is the simplest to understand.
#1 See the punctuated equilibrium example. I brought that up first and I'm not sure why you don't consider that persuasive evidence. It shows that in response to change the species changes quickly and reliably. What this point means is that evolution is
driven by the environment.
#2 The punctuated equilibrium argument dovetails well with the explanations for the variation in eyes. Compound eyes support the evolutionary strategy of insects. Survival via multiplicity and redundancy. Simple eyes like ocelli show up in spiders, which generally do not require good vision. Their niche requires them to be able to sense creatures in their web, and quite unsurprisingly they have very high sensitivity to vibration. This example if anything is a testament to the
non-randomness of evolution.
#3 For there to be any sort of spontaneous randomness a species needs to be in a situation where the environment favors either of two possible mutations equally and these mutations have to be comparably likely. Th evidence that this sort of spontaneous bifurcation happens is non-existent and the math indicates that it is vanishingly unlikely. For your example to make sense it would have to be reasonably probable that a snail could spontaneously generate a compound eye. Of course, this is exactly what doesn't happen in evolution, although it is the sort of thinking that creationists employ. It is this very sort of contradiction that indicates that evolution
must be non-random.
#4 If your claim is that the path of evolution is random, it simply reduces to the claim that history(or prehistory) is random. So, if you could, do you think you could start saying that rather than singling out evolution as being somehow different than the claim that comets are random? It would save people a lot of time in 'spotting the crackpot' so to speak.
There is quite a bit of evidence that it is chaotic, but that is why I started the other thread...
You may
think this, but there was by no means a consensus in the other thread. I was disputing your claim that this was somehow the consensus. Moreover, it seemed to me that many of the people who were most familiar with the topic tended to disagree.
Positive feedback loops tend to produce unstable systems, indeed they are often used to produce oscillators. Ecosystems have lots of positive feedback loops, which would predispose the system to chaotic behaviour.
Okey dokey. Once again you provide your intuitions. What positive feedback loops? The assertion that ecosystems have 'lots of positive feedback loops' is at best a hunch.
Moreover, I double checked with a friend of mine who knows a lot more about control systems than probably anyone on this board and he verified what I was pretty sure is already true.
Whether or not a system has positive feedback loops says nothing about whether the system is stable, unstable, chaotic, or not chaotic. A system with positive feedback loops can be characterized with a differential equation. Upon solving this equation whether the system is stable or not depends upon what the poles of the solution happen to be. Not surprisingly this is almost exactly the same claim as the one made by CoolSkeptic in the chaos thread. You
must be able to characterize the system to determine whether its chaotic.
Also what aspect of ecosystems do you assert is chaotic? As I understand it an ecosystem quickly approaches a Nash equilibrium. The aspects of game theory that dominate ecological science indicate regularity. For example, dawkins talks about how the distribution of sexes in a species is described reliably by a game theoretical approach.
Because that is how the maths works out. If they depend on position or momentum, they will eventually depend on quantum effects.
Um.....you are going to have to show me that math, because I think you are completely wrong. For example...I can calculate the position of a bullet after a certain amount of time from the momentum of the rifle during recoil, and the mass of the bullet. Change in any of the parameters leads to a linear change in the output. Thus the system is neither chaotic, nor unstable. Moreover it involves no quantum terms.
x = t*(p/m)
x = position
t = time
p = momentum
m = mass
Anything that affects the reproductive success of an organism, so including: the weather, asteroid strikes (rarely), competition, availability of mates, fertility, predation, parasites, food supply, territory, water supply, volcanoes (rarely), lightning strikes, etc...
Nice laundry list....here is my laundry list response:
Lightning
nly affects individuals, averages on level of species
Weather,Water supply: effects last much shorter periods of time than even individual creatures. Ie averages on the time scale of species existence.
Competition,availability,fertility, predation,parasites,food supply, territory: Described with a non-chaotic, non-random nash equilibrium.
Volcanos, Asteroid strikes: only random in the sense that 'the sun rising tomorrow' is random.
Of course, again, these arguments reduce to history being random as well
There are many positive feedback loops, one has been hypothesised for the non-recovery of the grand bannks cod fishery. The simple analysis being that the reduced adult cod population has reduced the predation of smaller fish. These smaller fish, in turn prey on the young cod fry. The reduced predation of the smaller fish has increased the predation of the cod-fry, which in turn acts to keep the cod population down.
Right....see my explanation on positive feedback. This example is perfect, this predation cycle drives down the cod population until either #1 the cod go extinct or #2 it stabilizes due to decreased food supply for small fish.
Stable Equilibrium Not Chaos
There are obviously negative feedback loops involved in ecosystems as well as positive ones, however looking at the history of evoution
Looking at the history of evolution what? Most systems in the biological world eventually reach a resource constraint, ie negative feedback, thus a system with positive feedback eventually moves into a negative state and the system stabilizes. Of course....see my previous analysis about how your preoccupation with feedback loops is irrelevant.
I don't get your question here. "Disruptive" mutations are rare, but they can be significant. If you are talking about geological timescales, then random events become more important in affecting how the developmetnal course of the ecosystem.
If the ecosystem starts to change, then (almost by definition) the organisms in that environment will be less well adapted to the altering environment than they would have been to the previous, stable environment. This would mean that variations are more likely to be eneficial than when the organisms were well-adapted.
Some of the positive feedbaclk loops would be those that frive the evolution of symbiotic relationships, where particular flowers and insects co-evolve.
My point is you have no idea how frequent these mutations are. My point is that if you look at the rate of birth and mutation in organisms we have reason to think that disruptive mutations are virtually certain on a geological time scale, even though they may be improbable on the scale of a generation.
For example, Gould has an example in the
structure of evolutionary theory with a proto-lungfish. This creature starts as a fish with no lungs, there is a drought(ie weather effect), the environment dries up, the fish evolves lungs, the drought ends the lungs quickly become vestigial and disappear. There is another drought, again the fish evolves lungs, again the drought ends and the lungs disappear. This happens over and over in the fossil record. You would think that lungs are an incredibly disruptive mutation, but it turns out that on a geological timescale, for that organism they were not. In fact, their development was inevitable.
Earlier on, I described the course of evolution as similar in some respects to a river system, these are often chaotic, and the course can seem stable for long times, but they can also change suddenly. If the topography is steep the change is less likely, if the gradients are shallow, then change is more likely. Similarly, in locally flat regions of the fitness landscape, or minor "saddles", slight changes could tip the evolution of the organism's descendents down different routes.
I remember this, but it is an example divorced from the theory and reality of evolution. Gould talks about this as well. In places that have a flat landscape the diversity of the gene pool increase to the point that additional mutations stop the creature from breeding with itself. If this cannot occur it cannot spread any further. Moreover the landscape is constrained by resource(energy) limitations in the environment. So there will always be resistance to moving away from the nash equilibrium and 'meandering' around the fitness landscape. The organism can only change when the fitness landscape changes.
I would also disagree that the assertions were "vigorously" shot down. I still contend that most physicists think that the timescales for quantum uncertainty to affect the weather is quite short. When I studied physics, the consensus seemed to be about 6-weeks. My very naive treatment of the numbers came to a conclusion that was not vastly different. Life has existed for over 3-billion years, so that is the sort of timescale that would be needed if random events didn't affect natural selection affecting the weather.
There certainly wasn't 'consensus' but it seemed like the people who were most knowledgeable suggested you learn some math. As to where that 6-weeks number comes from, as was noted in the other thread, unless you've got a secret model of weather you haven't published, then you are pulling that number out of your posterior.
Moreover these vague claims about weather don't prove anything about evolution, unless you are making the very non-mainstream claim that quantum effects are significant in climate. A rain storm isn't going to have any effect on a species, even a hurricane. You don't hear about any extinctions from those sorts of events, because even if we can't predict the specific time and strength, they happen several times every year and species are hardened against them. So how does weather even matter at all? Could you provide a concrete scenario.
As to 3-billion years...you are doing the analysis backwards. The longer the period of time the more likely that all different configurations are tried and any randomness averages out. (ie many hurricanes/monsoons per year)
Thanks, I do feel like I'm learning something from this even if it seems like some of my fellow forum-goers' ideas aren't really evolving.(lol, I can't help it with the corny jokes) At the very least, this discussion might convince someone to read a book by an expert on the subject.
