Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9162 total)
1 online now:
Newest Member: popoi
Post Volume: Total: 915,817 Year: 3,074/9,624 Month: 919/1,588 Week: 102/223 Day: 0/13 Hour: 0/0


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Do computer simulations support cumulative selection?
blitz77
Inactive Member


Message 1 of 12 (16049)
08-25-2002 1:56 AM


Weasel, a flexible program for investigating deterministic
computer ‘demonstrations’ of evolution

The program can be downloaded in the above link.
There are four different models-
quote:
Dawkins model (default)
In the Dawkins model (Fig. 1, Below right), the target sequence and parameters are set as per Dawkins’ original exercise. Running the model will show convergence on the target usually in 30 to 60 generations (iterations). Since this is a probabilistic exercise involving a random starting sequence and random mutations, the result will vary with each run.
Error Catastrophe model
Error catastrophe occurs when genetic information is destroyed by mutations at such a rate that all progeny are less fit than the parent/s so that selection cannot maintain the integrity of the genome and, in a Dawkinsian-type model, a target sequence cannot be achieved.
Adjusted mutation rate model
In effect, the mutation rate cannot be much greater than one per genome per generation. This then severely limits the rate of progress from a chimp-like species to human, if this were possible, even with perfect selection and all the other assumptions.
DNA Model
Any standard biochemistry text would describe how proteins are made from the information contained in the base sequences on DNA. We have provided a brief tutorial provided with the program (under ). An important difference between the DNA model and Dawkins’ Model, or any alphabet model, is that the DNA of an organism is not compared directly with the target as it is in alphabetical model. Another important factor is redundancy, some of the amino acids can be coded by different codons. With some codons, only the first two base pairs are needed to determine which amino acid is produced. This gives the genetic code some resistance to change. In some cases you would require more than one mutation to convert the code of one expressed amino acid into the code for another.
--Note: for faster simulations switch on the calc mutations by gaps which is effective when guarantee mutation = No. It is under the edit -> options menu, which instead uses an exponential probability distribution.
[This message has been edited by blitz77, 08-25-2002]
[This message has been edited by blitz77, 08-25-2002]

Replies to this message:
 Message 2 by Syamsu, posted 08-25-2002 4:37 AM blitz77 has not replied

  
blitz77
Inactive Member


Message 4 of 12 (16069)
08-26-2002 6:58 AM


Does anyone know where more serious simulations can be found?

Replies to this message:
 Message 5 by Andya Primanda, posted 08-27-2002 10:00 PM blitz77 has not replied
 Message 6 by Me, posted 09-02-2002 8:46 AM blitz77 has replied

  
blitz77
Inactive Member


Message 7 of 12 (16408)
09-02-2002 9:16 AM
Reply to: Message 6 by Me
09-02-2002 8:46 AM


Hmmm? That circuit did not actually produce what was required-
quote:
In essence, the evolving circuit had cheated, relaying oscillations generated elsewhere, rather than generating its own.
I'm sure you can call this nitpicking, but using 10 transistors and switches to make an oscillator is not that hard. And after "several thousand generations" the best they could come up with was a radio, producing oscillations from radio waves using a long track in the circuit as a receiver rather than producing them from from the transistors. But it is quite interesting anyway
I've played around with electronic circuits long enough to know that often, if a speaker is involved, you can hear AM radio on it. An appliance nearby, you hear noise.
[This message has been edited by blitz77, 09-02-2002]

This message is a reply to:
 Message 6 by Me, posted 09-02-2002 8:46 AM Me has replied

Replies to this message:
 Message 8 by Me, posted 09-02-2002 9:48 AM blitz77 has replied

  
blitz77
Inactive Member


Message 9 of 12 (16416)
09-02-2002 10:00 AM
Reply to: Message 8 by Me
09-02-2002 9:48 AM


quote:
Well - nitpicking and cheating, true - but I read the story as indicating a principle, for which simplicity is a benefit. OK, you can make a multivibrator with two transistors, but my first point was that something 'new' had emerged. Creationists argue strongly that micro-evolution - 'improving' a species - is possible, but that a new 'vital' organ cannot be generated, so a 'new' animal cannot be evolved. Here we have a radio receiver where before we had a signal generator.
My second point was not that the design was hard, but that it was done without directed design, by evolution, rather than by intention. This is surely also of relevance to the evolution/creation debate. Evolutionary pressures just made use of the induced AM oscillations you mentioned would be in the environment.
Here you have all the components required-the transistors did not pop up from a morass of metal. This is the evolution of something which uses material already existent. Classifying linking up of transistors in the same class as macroevolution of new organs is quite a leap.

This message is a reply to:
 Message 8 by Me, posted 09-02-2002 9:48 AM Me has replied

Replies to this message:
 Message 10 by Me, posted 09-02-2002 11:23 AM blitz77 has not replied
 Message 11 by Mammuthus, posted 09-02-2002 11:41 AM blitz77 has not replied

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024