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Author Topic:   Evolution is random! Stop saying it isn't!
Wounded King
Member (Idle past 2202 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 31 of 99 (415441)
08-10-2007 4:24 AM
Reply to: Message 24 by Bodhitharta
08-09-2007 8:50 PM


Re: random selection and a model of evolution
What about them? They are the ones which lead to an individual having more offspring and which will tend to be over represented in the next generation.

If you accept 'random' mutation then unless you consider it impossible that DNA can change in any way which leads to an organism having increased reproductive success you must also accept that some proportion of random mutations will be beneficial.

TTFN,

WK


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Doddy
Member (Idle past 4016 days)
Posts: 563
From: Brisbane, Australia
Joined: 01-04-2007


Message 32 of 99 (415450)
08-10-2007 6:35 AM
Reply to: Message 29 by Bodhitharta
08-10-2007 4:05 AM


Re: random selection and a model of evolution
Natural selection is just a description of the observation that some organisms have more offspring than others. Thus, it amplifies those sort of organisms, which are usually those that cope the best with their environment. There is no design in that system, according to evolutionary biologists, just a straight-forward observation.

However, even a filter is random (by the definition I outlined in my original post). Take for example passing a solution through a piece of filter paper, which is a one-step filter (compared to the constant filtering of natural selection). While you can say that it is more likely for a small particle to pass through than a larger one, you can't actually predict whether a particle will pass through or not.

Thus, one must conclude that if evolution through natural selection is the explanation for life on earth, then random processes can create complex systems.


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This message is a reply to:
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Bodhitharta
Member (Idle past 4172 days)
Posts: 10
From: Tacoma, WA, USA
Joined: 08-08-2007


Message 33 of 99 (415451)
08-10-2007 6:40 AM
Reply to: Message 32 by Doddy
08-10-2007 6:35 AM


Re: random selection and a model of evolution
I think basic DNA goes against any truly randomness as a rule because the instructions of DNA is very predictable.
This message is a reply to:
 Message 32 by Doddy, posted 08-10-2007 6:35 AM Doddy has not yet responded

Replies to this message:
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Wounded King
Member (Idle past 2202 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 34 of 99 (415454)
08-10-2007 7:10 AM
Reply to: Message 33 by Bodhitharta
08-10-2007 6:40 AM


Re: random selection and a model of evolution
This makes no sense.

Could you take a bit more time to explain your position. At the moment you are just giving glib one sentence responses to a whole lot of lengthier rebuttals, and none of your answers seem to have any actual substance or sometimes even coherence.

This latest post is a good example and is similar to your response to me

So what about "Random" positive mutations?

Which was asking about something I had already covered in my post

Now you respond to Goddy with a post which doesn't address his point and doesn't even make grammatical, let alone scientific, sense.

What is it about the 'instructions of DNA' that is very predictable?

TTFN,

WK


This message is a reply to:
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Percy
Member
Posts: 18370
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.9


Message 35 of 99 (415455)
08-10-2007 7:23 AM
Reply to: Message 33 by Bodhitharta
08-10-2007 6:40 AM


Re: random selection and a model of evolution
Bodhitharta writes:

I think basic DNA goes against any truly randomness as a rule because the instructions of DNA is very predictable.

I'll start by pointing out that this is a meaningless statement. The instructions of DNA are not, to a large extent, predictable. If the instructions were very predictable, then if I gave you the nucleotide sequence GACT... you could tell me what comes after the T. But you can't. No one can. That's because DNA instructions are not "very predictable."

DNA is copied during reproduction, and the copying process, which is a natural process, is imperfect. Practically every cell division, whether for single celled organisms or for gametes (reproductive cells such as sperm and egg) contains mistakes from the copying process, which we call mutations. Most mutations are simple point nucleotide substitutions, though some mutations are much more complicated. Where mutations occur, to a first level of approximation, is random.

Natural selection is not random. Organisms are selected for by the environment. Cold environments will select against hairless cats and for polar bears, and warm environments will select for hairless cats and against polar bears.

--Percy


This message is a reply to:
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Doddy
Member (Idle past 4016 days)
Posts: 563
From: Brisbane, Australia
Joined: 01-04-2007


Message 36 of 99 (415463)
08-10-2007 8:28 AM
Reply to: Message 34 by Wounded King
08-10-2007 7:10 AM


Re: random selection and a model of evolution
Wounded King writes:

What is it about the 'instructions of DNA' that is very predictable?

I think Bodhi is talking about the genetic code, where once you know the reading frame, you can predict the sequence of the polypeptide produced after transcription and translation.


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This message is a reply to:
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Doddy
Member (Idle past 4016 days)
Posts: 563
From: Brisbane, Australia
Joined: 01-04-2007


Message 37 of 99 (415464)
08-10-2007 8:29 AM
Reply to: Message 35 by Percy
08-10-2007 7:23 AM


Re: random selection and a model of evolution
Percy writes:

Natural selection is not random. Organisms are selected for by the environment. Cold environments will select against hairless cats and for polar bears, and warm environments will select for hairless cats and against polar bears.

By what definition of randomness?


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This message is a reply to:
 Message 35 by Percy, posted 08-10-2007 7:23 AM Percy has responded

Replies to this message:
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Wounded King
Member (Idle past 2202 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 38 of 99 (415469)
08-10-2007 9:14 AM
Reply to: Message 36 by Doddy
08-10-2007 8:28 AM


Re: random selection and a model of evolution
Thats what I assumed he meant, but that covers only the barest fraction of what DNA actually does, and it seems to have no relevance at all to randomness.

TTFN,

WK


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Percy
Member
Posts: 18370
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.9


Message 39 of 99 (415473)
08-10-2007 9:45 AM
Reply to: Message 37 by Doddy
08-10-2007 8:29 AM


Re: random selection and a model of evolution
Goddy writes:

Percy writes:

Natural selection is not random. Organisms are selected for by the environment. Cold environments will select against hairless cats and for polar bears, and warm environments will select for hairless cats and against polar bears.


By what definition of randomness?

By the same definition that it isn't random that you don't freeze in the summer and you don't swelter in the winter.

--Percy


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Replies to this message:
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RAZD
Member
Posts: 19815
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 10.0


Message 40 of 99 (415477)
08-10-2007 10:44 AM
Reply to: Message 30 by Bodhitharta
08-10-2007 4:08 AM


Re: random mutation and non-random selection
So is the male elk acting with intention?

The male elk is acting with "intention" to pass on his genes (mate) to the next generation - whether that "intention" is conscious or not is irrelevant: he gets the opportunity to do so by defeating the other male elk. His genetic and developmental makeup defeated their genetic and developmental makeup.

BTW, Are you saying that in an accident or terrorist attack "natural selection" is taking place?

Not necessarily.

An event that kills all individuals in its path is a different kind of selection - one not based on the genes of the victims vs non-victims. The result is still a change in the gene pool, but this is usually referred to as genetic drift rather than natural selection. The terrorist attack is a catastrophic event, like a volcano or earthquake or fire. Another source of genetic drift is accidents: a tree falling on a person, a lightening strike.

http://en.wikipedia.org/wiki/Genetic_drift

quote:
In population genetics, genetic drift is the statistical effect that results from the influence that chance has on the survival of alleles (variants of a gene). The effect may cause an allele and the biological trait that it confers to become more common or more rare over successive generations. Ultimately, the drift may either remove the allele from the gene pool or remove all other alleles. Whereas natural selection is the tendency of beneficial alleles to become more common over time (and detrimental ones less common), genetic drift is the fundamental tendency of any allele to vary randomly in frequency over time due to statistical variation alone, so long as it does not comprise all or none of the distribution.

http://evolution.berkeley.edu/evosite/evo101/IIIDGeneticdrift.shtml

quote:
Genetic drift—along with natural selection, mutation, and migration—is one of the basic mechanisms of evolution.

In each generation, some individuals may, just by chance, leave behind a few more descendents (and genes, of course!) than other individuals. The genes of the next generation will be the genes of the “lucky” individuals, not necessarily the healthier or “better” individuals. That, in a nutshell, is genetic drift. It happens to ALL populations—there’s no avoiding the vagaries of chance.

... Genetic drift affects the genetic makeup of the population but, unlike natural selection, through an entirely random process. So although genetic drift is a mechanism of evolution, it doesn’t work to produce adaptations.


Genetic Drift is a random process.

When I said (Message 28) "When one individual dies and another lives selection has occurred" I should have been a little more specific about the cause of death: predation, disease, age, physical inability to survive flood, drought, fire when others could, are all selection where there is an opportunity to survive based on the genetic and developmental makeup of some individuals compared\relative to other individuals.

If there was a genetic and developmental ability of some people to survive a terrorist attack compared to other people then such would be natural selection.

For natural selection to operate on the genetic and developmental makeup of individuals those makeup elements need to be "tested" by the selection event.

Enjoy.


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Doddy
Member (Idle past 4016 days)
Posts: 563
From: Brisbane, Australia
Joined: 01-04-2007


Message 41 of 99 (415478)
08-10-2007 10:44 AM
Reply to: Message 39 by Percy
08-10-2007 9:45 AM


Re: random selection and a model of evolution
Ah, I think I get it. Which organisms survive to pass on their genes is actually predictable, at least in the extreme forms of mutations and variations. Is that right?

What about weaker selection pressures? How are they non-random?


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We seek contributors with a knowledge of Intelligent design to expand and review our page on this topic.

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Replies to this message:
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Percy
Member
Posts: 18370
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.9


Message 42 of 99 (415488)
08-10-2007 12:00 PM
Reply to: Message 41 by Doddy
08-10-2007 10:44 AM


Re: random selection and a model of evolution
Goddy writes:

Ah, I think I get it. Which organisms survive to pass on their genes is actually predictable, at least in the extreme forms of mutations and variations. Is that right?

Which organisms survive to reproduce and pass on their genes is non-random but usually not predictable except under laboratory conditions where all environmental and genetic factors can be controlled. You could, I suppose, make predictions for extreme cases. For instance, if you dropped off a hundred polar bears in Guatemala this summer then came back next summer to see how many were still alive, it likely would be very few. But precisely or even approximately how many would survive to have cubs next spring? Who could predict, too many variables. Maybe they'll all survive by successfully taking up residence near human garbage dumps. Maybe they'll all die from a tropical disease. The real world has so many variables that meaningful prediction often isn't a realistic possibility. Certainly a polar bear population transported to the tropics would experience severe environmental stress that should have the result of many fewer offspring next spring, but whether that's what would really happen, who knows. Of course, a biologist familiar with polar bears would be aware of the key factors and could probably tell us some things with a fair degree of certainty. For example, perhaps he knows that polar bears can only hunt on sea ice and would never take up residence near human habitation (I have no idea whether that's really true, this is just an example), in which case he knows not a single polar bear would survive a year in Guatemala.

It's in the laboratory where both the genetic variation and the environment can be strictly controlled and usually working with organisms with short generation times such as mosquitoes or mice that the influence of environment can be properly studied.

What about weaker selection pressures? How are they non-random?

Just for the sake of discussion, let's say that polar bears have 0% probability of surviving a year in the tropics. That's a very strong selection pressure, and you can see that it is non-random. But what if we only transport the polar bears as far as Texas. Now the selection pressure isn't as great, and more would survive a year. Obviously this still isn't non-random, it's just that in a cooler climate they have a better chance of survival, call it 50% just to have a figure.

Now consider that we only transport the polar bears as far as Montana. That's a pretty cold state much of the time, so the selection pressure is again reduced, and maybe 75% survive a year this time. And of course if we leave the polar bears in their natural habitat most survive a year, perhaps 90%. But notice that as you reduce the selection pressure by placing the polar bears in habitats that more and more closely match their natural habitat that while the mortality rate is less the selection pressure is still non-random.

--Percy


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RAZD
Member
Posts: 19815
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 10.0


Message 43 of 99 (415503)
08-10-2007 1:51 PM
Reply to: Message 42 by Percy
08-10-2007 12:00 PM


side on Polar Bears
Maybe they'll all survive by successfully taking up residence near human garbage dumps. ... Of course, a biologist familiar with polar bears would be aware of the key factors and could probably tell us some things with a fair degree of certainty. For example, perhaps he knows that polar bears can only hunt on sea ice and would never take up residence near human habitation (I have no idea whether that's really true, this is just an example), ...

Google "Churchill Manitoba"

http://www.pbs.org/wnet/nature/polarbear/

quote:
Each October, the remote Canadian town of Churchill in Manitoba plays host to some very unusual guests. More than a thousand hungry polar bears gather there to await the refreezing of Hudson Bay and then move out on the ice in pursuit of their traditional winter diet of seal.

If memory serves they do take up residence near the garbage dump.

More to the point for long term survival would be breeding success. Polar Bears habitually build dens in snow.

Enjoy.

Edited by RAZD, : subtitle


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we are limited in our ability to understand
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This message is a reply to:
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Doddy
Member (Idle past 4016 days)
Posts: 563
From: Brisbane, Australia
Joined: 01-04-2007


Message 44 of 99 (415574)
08-10-2007 10:37 PM
Reply to: Message 42 by Percy
08-10-2007 12:00 PM


Evolution = pseudo-random?
Percy writes:

But notice that as you reduce the selection pressure by placing the polar bears in habitats that more and more closely match their natural habitat that while the mortality rate is less the selection pressure is still non-random.

Ok, I can see that.

Therefore, what sort of definition for randomness should I be using? I'm trying to use the definition that matches the most closely what creationists usually mean when they imply that "evolution is random" or that "life just happened". But I'm having a hard time, because definitions appear to be prohibited in creation science.

It appears to me that evolution is non-random in the same way that rolling two dice is non-random - the results cluster around 7 (central limit theorem), but the actual result isn't predictable by humans, although it is entirely controlled by deterministic properties.

Would it be safe to say evolution is pseudo-random? As in, it would be predictable if you had access to all the variables.


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This message is a reply to:
 Message 42 by Percy, posted 08-10-2007 12:00 PM Percy has responded

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RAZD
Member
Posts: 19815
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 10.0


Message 45 of 99 (415575)
08-10-2007 11:01 PM
Reply to: Message 44 by Doddy
08-10-2007 10:37 PM


How about directed ?
You could say that the direction of adaptation is predictable -- towards a more heat tolerant polar bear -- but that the degree and kind of adaptation is not predictable. It's like a compass, it tells you (predicts) where north is but not where your camp is.


Join the effort to unravel AIDS/HIV, unfold Proteomes, fight Cancer,
compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click)


we are limited in our ability to understand
by our ability to understand
RebelAAmericanOZen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.

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