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Author Topic:   Evolution is random! Stop saying it isn't!
Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 16 of 99 (415304)
08-09-2007 11:10 AM
Reply to: Message 13 by Bodhitharta
08-08-2007 11:14 PM


Re: random selection and a model of evolution
Hi Bodhitharta,
I see you've returned and edited your post, but you included no indication of what you changed, and I never saw the original. I'm guessing you added the explanation that appears after the link?
Anyway, that's good if that's what you did, but the other point made to you is that this is off-topic in this thread. If you'd like to discuss your own views then you should propose a new thread over at [forum=-25]. You can just copy the text of your message for the proposal.
--Percy

This message is a reply to:
 Message 13 by Bodhitharta, posted 08-08-2007 11:14 PM Bodhitharta has replied

Replies to this message:
 Message 17 by Bodhitharta, posted 08-09-2007 3:28 PM Percy has replied

  
Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 18 of 99 (415354)
08-09-2007 4:55 PM
Reply to: Message 17 by Bodhitharta
08-09-2007 3:28 PM


Re: random selection and a model of evolution
Bodhitharta writes:
I thought this was on topic, the reason is because I am saying that evolution is random and yet life is not random.
That's not at all what you said in your Message 13. If you'd like to join the discussion here about randomness then welcome aboard, while if you want to discuss the assertions you make in Message 13 then you should propose a new thread. And, of course, you can do both.
--Percy

This message is a reply to:
 Message 17 by Bodhitharta, posted 08-09-2007 3:28 PM Bodhitharta has replied

Replies to this message:
 Message 20 by Bodhitharta, posted 08-09-2007 8:06 PM Percy has not replied

  
Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


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:
 Message 33 by Bodhitharta, posted 08-10-2007 6:40 AM Bodhitharta has not replied

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 Message 37 by Doddy, posted 08-10-2007 8:29 AM Percy has replied

  
Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


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

This message is a reply to:
 Message 37 by Doddy, posted 08-10-2007 8:29 AM Doddy has replied

Replies to this message:
 Message 41 by Doddy, posted 08-10-2007 10:44 AM Percy has replied

  
Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


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

This message is a reply to:
 Message 41 by Doddy, posted 08-10-2007 10:44 AM Doddy has replied

Replies to this message:
 Message 43 by RAZD, posted 08-10-2007 1:51 PM Percy has not replied
 Message 44 by Doddy, posted 08-10-2007 10:37 PM Percy has replied

  
Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 46 of 99 (415577)
08-10-2007 11:20 PM
Reply to: Message 44 by Doddy
08-10-2007 10:37 PM


Re: Evolution = pseudo-random?
Doddy writes:
Would it be safe to say evolution is pseudo-random? As in, it would be predictable if you had access to all the variables.
While this isn't an invalid perspective, it isn't one that leads to any useful insights. The creationist claim that evolution is random is just plain wrong, because natural selection is not random. The easiest way to see this is the example of breeding.
Artificial selection or breeding, what humans do in their own gardens and barns, operates on the same principles as natural selection. When humans perform animal or plant breeding they are selecting for specific qualities, such as color in flowers or speed in horses. There is nothing random about the selection process. If the breeder wants red flowers, yellow flowers will not contribute a single seed to the next generation.
There is also nothing random about the selection process in nature, the process we call natural selection, it's just a lot more complicated. It's almost never a single factor that determines which individuals get to pass on their genes to the next generation. Instead of just flower color being a factor, everything's a factor, like the length of the stem, the number of leaves, the stem diameter, the branching pattern of the roots, the texture of the petals, the length of the stamen, etc., etc., etc. Through natural selection the environment shapes and molds populations of species to be best suited to that environment. The most common lifeforms in any region will be well adapted to it, it could not be any other way.
And that's why the process of evolution, which is descent with modification and natural selection, is not a random process. Any environment will always hone the resident life into forms most suitable for it. If evolution were truly a random process then populations would be continually evolving away from being well adapted to their environment, but we never see this. We should never see this, because poorly adapted life is less likely to contribute to the next generation.
Once the light bulb goes on it's so obvious that everyone who achieves this realization echos the feelings of Thomas Huxley, Darwin's most stalwart defender, who said after reading Origins for the first time, "How extremely stupid not to have thought of that."
--Percy

This message is a reply to:
 Message 44 by Doddy, posted 08-10-2007 10:37 PM Doddy has replied

Replies to this message:
 Message 47 by Doddy, posted 08-11-2007 1:32 AM Percy has replied

  
Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 48 of 99 (415633)
08-11-2007 9:49 AM
Reply to: Message 47 by Doddy
08-11-2007 1:32 AM


Re: Evolution = pseudo-random?
Doddy writes:
What do creationists usually mean when they make the quip that 'evolution is random' or 'amounts to blind chance'?
I don't think I could say with any certainty, but when creationists refer to the changes that occur during reproduction as random they are certainly correct. The copying errors that occur during cell division are random, though there are certainly mutational hot spots where copying errors are more likely. And in sexual species, which sperm combines with which egg is certainly random (I call this allele remixing, but there's probably a proper technical term for it), and I'd have to read up to refresh my memory, but somewhere in the process, maybe during gamete (sexual cells with only half of each chromosome pair) production or maybe during egg/sperm combining, the genes are shuffled around somewhat.
But though mutation and variation are essential inputs into the evolutionary process, the end result is not random, and creationists who insist that it is simple don't understand the power of natural selection. Even when simple bacterial evolution experiments are described where the resulting bacterial populations have evolved to survive and even thrive in whatever adverse environmental conditions the experimenters have introduced, many creationists won't understand this. Some will respond with, "Well, the bacteria is still a bacteria," even though speciation is completely beside the point of what the experiment is illustrating, and others will just continue blindly insisting that evolution is random, I have no idea why.
But in the end the word "random" is just a label. If creationists prefer to redefine "random" within their own minds to include the outcome of evolution, it doesn't change the fact that descent with modification combined with natural selection produces increasingly successful adaptation to the environment.
--Percy

This message is a reply to:
 Message 47 by Doddy, posted 08-11-2007 1:32 AM Doddy has not replied

  
Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 55 of 99 (415845)
08-12-2007 2:30 PM
Reply to: Message 53 by epo5
04-16-2003 7:21 PM


Re: The Fallacy of Evolution
Hi Epo5,
There seems to be some confusion. EvC Forum exists for debate between creationists and evolutionists. You're advocating the creationist viewpoint. We refer to those who advocate the creationist viewpoint as creationists. All Doddy did was refer to the creationist viewpoint, the one that you yourself are espousing. He didn't mention creation or religion, he simply referred to the the other side in the debate, creationists. That's all. No creation, no religion. You mentioned creation and religion, not Doddy.
--Percy

This message is a reply to:
 Message 53 by epo5, posted 04-16-2003 7:21 PM epo5 has replied

Replies to this message:
 Message 56 by epo5, posted 08-12-2007 6:02 PM Percy has replied

  
Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 58 of 99 (415914)
08-12-2007 9:57 PM
Reply to: Message 56 by epo5
08-12-2007 6:02 PM


Re: The Fallacy of Evolution
epo5 writes:
What's this?: "creationists are right when they..."
"Creationists" is a reference to creationists, which is you and Nemesis_juggernaut and Rob and Buzsaw and so on, as opposed to "evolutionists", which is Doddy and me and RAZD and so on. "Creationists" isn't a reference to creation. It isn't a reference to religion. It's a reference to one side of the debate.
If this isn't making sense to you then why not just sit back and lurk for while. Enjoy the show!
--Percy

This message is a reply to:
 Message 56 by epo5, posted 08-12-2007 6:02 PM epo5 has not replied

  
Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 61 of 99 (415990)
08-13-2007 9:15 AM
Reply to: Message 59 by epo5
08-13-2007 1:13 AM


Re: Got it.
I can only echo what Doddy said. Your initial message touched on many different topics. Pick one and submit a thread proposal at the [forum=-25] forum.
Messages aren't usually deleted at EvC Forum.
--Percy

This message is a reply to:
 Message 59 by epo5, posted 08-13-2007 1:13 AM epo5 has not replied

  
Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 93 of 99 (416389)
08-15-2007 3:08 PM
Reply to: Message 92 by bdfoster
08-15-2007 2:47 PM


Re: random selection and a model of evolution
Once you start talking about probability distributions you probably exceed the comprehension level of a great deal of your intended audience. How about approaching it this way when discussing randomness and natural selection with laypeople:
In natural selection, we define random to mean that which individuals survive to produce offspring has nothing to do with fitness. The least fit individuals would have as good a chance of producing progeny as the most fit.
But the reality of natural selection is that the most fit individuals produce more progeny than the least fit. This is not at all random.
Hence, natural selection is not random.
--Percy

This message is a reply to:
 Message 92 by bdfoster, posted 08-15-2007 2:47 PM bdfoster has not replied

  
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