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  Topic: Darwin was Wrong, Another way of creating species< Next Oldest | Next Newest >  
DaveRAFinn



Posts: 15
Joined: April 2005

(Permalink) Posted: April 29 2005,04:19   

Evolution Thoughts
If you are about to die you have a freedom to take risks that you would not normally do.

A simple and obvious idea.

But if you are a species facing extinction and the risk is elective mutation then the combination is enough to destroy Darwins theory on the Origin of Species.

If a species facing extinction happens, because of its genetic heritage, to risk elective mutation it increases the chances of a change that will allow a successor. There are no costs, the species will be extinct anyway. The succesor will retain the risk taking genes. After enough extinction events most of the surviving species will have adopted risk taking at extinction. Once you know what to look for the evidence is easy to find. A bacterium that will live happily unchanged for thousands of years will increase its mutation rate a millionfold when threatened with extinction by an antibiotic.

The following article was submitted to the infidels web site, but apparently proved too much for their religious views.

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The short disproof of the Darwinian theory of the origin of species.

The Darwinian theory of evolution is based on the idea of slow steady changes arising from accumulated mutations. It is slow because, according to the theory, mutation is disadvantageous. The only mutations occur as a result of unavoidable errors in transcribing genetic information.

The normal expression of the disadvantage of mutation is in terms of there being far more disadvantageous mutations than favourable ones. This is true but irrelevant. Note that company balance sheets do not show the number of items of expenditure and income, only the value. Small numbers of high value transactions have the same effect as large numbers of low value transactions. The correct value for mutation is obtained by considering all possible mutations and assigning them a probability and a cost (or benefit). The net cost (benefit) of mutation is the sum of the costs (benefits) multiplied by the probability that they will individually occur.

Costs are not fixed. Supply and demand applies. A mutation that conserves water is of little value in a lake, of great value in a desert and the value will change with the environment. Of more importance, a beneficial mutation increases the long term probability of an organism having descendants and is limited by the impossibility that the probability can exceed one; similarly a deleterious mutation decreases the long term probability of an organism having descendants and is limited by the impossibility of the probability being less than zero.

Over a time scale, usually taken as a generation, the numbers of a population vary. The ratio of the numbers in one generation to the numbers in the preceding generation is a reproduction ratio. If the environment of an organism changes sufficiently for the long term reproduction ration to fall below one then the population of the organism will become extinct and disappear. At any point where the reproduction ratio drops sufficiently to virtually ensure extinction the long term probability of the organism having descendants is essentially zero. Consequently, the cost of deleterious mutations, as a fraction of this must also be zero. The only mutations which contribute anything to the cost(benefit) calculation for mutation are the small proportion of beneficial mutations which return the reproduction ratio back above one. All other mutations have no net effect on the slide into extinction, they can only affect the speed at which this state is achieved.

Once the long term reproduction ratio of a population drops below one the organism is in a position where mutation has a net positive effect. It has literally nothing to lose and a slight possibility of survival to look forward to. When mutation is a net good then more mutation is better and increases the possibility of a favourable outcome. It follows that under these conditions any organism having any genetic disposition to respond to the significant drop in reproduction rate by increasing its rate of mutation will have a greater long term probability of having descendents. The tendency to mutate at incipient extinction is genetically favoured. The greater the extent to which mutation is increased and the greater the accuracy with which the condition is detected the greater the advantage for the organism.

The process of mutating at extinction has positive feedback, compound interest in economic terms. Once initiated it will increase as the more extreme exponents of the process gain ever increasing advantage from electing to mutate. The limits are a totally accurate recognition of the state where mutation is advantageous and whatever turns out to be the upper limit of the mutation rate that will still allow any form of survival of the organism. Until these limits are reached the mutations, and the new species resulting from these mutations will increase with time. Eventually the numbers can be expected to reach and exceed the numbers of new species produced by Darwinism.

The condition that the two mechanisms, Darwinism and mutation at extinction, have exchanged as the primary producer of new species is easily detected. Following the crossover the number of species will show an abrupt rate of increase in numbers as the increasing rate of the extinction mechanism becomes apparent. Species will increasingly be created in the brief windows of extinction giving a fossil record with far fewer intermediate forms than under Darwinism with massive increases in the variety of life forms following periods of mass extinction. Species like bacteria will respond almost instantaneously to life threatening pollution and chemical hazards. There will be a marked difference in the rate of evolution in hazardous environments, such as land compared with the more benign ocean environments. The need to accurately gauge the population increase and decrease will lead to complex behaviours sensitive to population numbers. Etc.

Recognise it? Darwinism has not been the major evolutionary mechanism producing new species for quite some time.

********

So there you have it. Yes Darwinism exists, yes it works to keep species well adapted, yes it occasionally produces a new species, and yes, if you look at a species it will normally be the only form of exolution on display. But in the brief
periods of extinction wild risk taking changes occur producing most of the new species.

This description only shows the what of the evolutionary process, not the how. I do have an outline of how I think it works but

a) I am not a trained biologist so my account will undoubtedly contain errors that would be siezed on as reasons for ignoring what I am saying.

b) There are some potentially very valuable medical uses of evolution and I would like to try for some retirement income. (offers from pharmaceutical or similar companies welcomed - state the percentage of the profits you are willing to let me have).

  
Henry J



Posts: 4114
Joined: Mar. 2005

(Permalink) Posted: April 29 2005,11:38   

The term "Darwinism" seems to mean whatever aspect of evolution theory a particular speaker happens to disagree with. With that shifting of meaning from one speaker to another, it might be better to avoid using that term.

As for the idea of increased mutation rate on population drop, it sounds plausible to me (though I'm not a biologist).

But as to whether or not it's inconsistant with current theory (inconsistency with Darwin's original theory is irrelevant), I don't see any reason to think it's contrary to the currently accepted theory.

About the notion that evolution theory claims only gradual changes over an entire species - that wasn't even what Darwin said; it was the scientists that followed later that added that bit, and scientists today certainly don't think all evolution was gradual (some of it, but not all, maybe not even most).

Henry

  
sir_toejam



Posts: 846
Joined: April 2005

(Permalink) Posted: April 29 2005,17:02   

"The Darwinian theory of evolution is based on the idea of slow steady changes arising from accumulated mutations. It is slow because, according to the theory, mutation is disadvantageous. The only mutations occur as a result of unavoidable errors in transcribing genetic information."

this is not actually precise.  

1.  the idea of slow and steady is a bit of an oversimplification that is based on what darwin himself thought without the benefit of the genetic information we have available.  it doesn't correctly translate to modern evolutionary theory.

2.  there is no assumption in modern theory as to the relative advantage/disadvantage of any specific mutation event.  relative selective pressures determine this, not any a-priori assumption.

3.  mutations can occur by a variety of mechanisms other than the one you list.  Moreover, errors are not "unavoidable" in any specific sense with regards to transcription itself.  there are actually very good mechanisms in place to prevent transcription errors, which make them typically quite rare.  hence, the sources of mutation don't always arise strictly from transcription "errors", but could arise pre-transcription from any of a number of sources; oncogenes, for example.

"The correct value for mutation is obtained by considering all possible mutations and assigning them a probability and a cost (or benefit). The net cost (benefit) of mutation is the sum of the costs (benefits) multiplied by the probability that they will individually occur."

Funny you should mention this; one of the leading evolutionary theorists of all time, Robert Trivers, is attempting to do just that:  attempting to produce equations that balance the absolute inclusive fitness of a trait.  the reason i point this out is that there are so many variables to calculate in real-world examples of inclusive fitness that calculating the "value" for any specific trait would be extremely difficult.

for example, you could have multiple, competing selective pressures on any given trait.  how would you be able to determine ALL the relevant selective pressures in the field?  Moreover, at the genetic level, traits can be linked.  While there might be significant pressure against one trait, it might be linked to another trait that is even more "favored".  Just two small examples, but you can see how complicated this can get.

You can't even correctly determine the "probability that they will individually occur" without more detailed knowledge of what factors into that.  even in its most simplistic form you propose, that of simple 'translation errors', it would take a phenomenal effort to calculate what the factors and frequency of translation errors occur within an individual population in the field, which is all that really matters.

"Of more importance, a beneficial mutation increases the long term probability of an organism having descendants and is limited by the impossibility that the probability can exceed one; similarly a deleterious mutation decreases the long term probability of an organism having descendants and is limited by the impossibility of the probability being less than zero"

congratulations, you essentially just reworded what amounts to the theory of inclusive fitness.

"At any point where the reproduction ratio drops sufficiently to virtually ensure extinction the long term probability of the organism having descendants is essentially zero. Consequently, the cost of deleterious mutations, as a fraction of this must also be zero."

the cost to whom?  individuals do not "divine" the relative value of deleterious mutations, nor do they consider the value of maintaining the "species".

On the contrary, it really depends on what specific selective pressure you are talking about as to what strategy actually makes sense under those pressures.

you can't generalize "environment" as a selection pressure per say.  There are numerous selective pressures that could conflict with each other and still come under the heading "environment".  Even if you restrict the selective pressures to purely physical ones.  However, restriction to purely physical selection pressures is very unrealistic.

you are mistaking something general (environment) with something very specific (a specific selective agent) when you use the example of a colony of bacteria "threatened" by an antibiotic.


look, essentially what the argument proposes is that generalists are favored under some conditions, specialists under others.  However, this has little to do with genetic mutation rates.  Selection could just as easily act on the variablity already extant in a population.  under such circumstances, it would simply favor those individuals with offspring already more compatible with whatever the primary selective pressure is.  In fact, it predicts the exact opposite of increased mutation.  I would expect to see those individuals with the greatest fitness under the restricted circumstances to be those with less variability in their offspring, but whose traits are more compatible with whatever the most prevalent selective pressure at the time is.  these individuals would have the most surviving offspring, not the ones with increased variability.

aside from all of that, what you are proposing is essentially that environmental bottlenecks end up producing most species, through a genetic mutation mechanism.  the problem with that is you can more easily explain it through standard evolutionary theory.

once you have an extreme bottlneck, afterwards you have a whole buch of blank niches to fill.  intrapsecies competion would then be a far greater selective pressure than interpsecies ones, which would then favor individuals to move into new niches.

no need to propose massive genetic mutation as a response to bottleneck-level selective pressures.

see?

  
Sheikh Mahandi



Posts: 47
Joined: May 2005

(Permalink) Posted: May 19 2005,14:25   

This sounds like a description of punctuated equilibrium as proposed by Niles Eldredge, and Stephen Jay Gould.

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"Love is in the air, everywhere I look around,.....Love is in the air, every sight and every sound,......"

  
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