What prevents evolution?

[Sephus]

[ QUOTE ]
Speciation, for purposes of discussion, is where one internally fertile group develops into another.

There is no applicable instance of this phenomenon in the data. In fact, it's unlikely even from the perspective of logic. How can there be descent of any sort through a discontinuity in fertility?

[/ QUOTE ]

this is the last time i'm going to repeat the same idea. there doesn't have to be a discontinuity between one generation and its children.

let's say A is one generation within a population, B is the next, etc. suppose a member of A can mate successfully with a member of B 90% of the time and this rule generally holds over time, meaning B can mate successfully with C 90% of the time. it does NOT follow that A can mate successfully with C 90% of the time. the percentage could very well tend to zero as the gap gets larger depending on what's happening to the DNA over time, even though each generation has a very good success rate when mating with its contemporaries.

don't get hung up by taking it too literally, or suppose that A->C is actually 89.99%, and A->A(100,000) is 0%

[Skidoo]

And yet again, that's only a partial answer.

Now you have to account for the lack of a similar degradation in mutual fertility BETWEEN MEMBERS within the successive generations.

[Sephus]

[ QUOTE ]
And yet again, that's only a partial answer.

Now you have to account for the lack of a similar degradation in mutual fertility BETWEEN MEMBERS within the successive generations.

[/ QUOTE ]

it's a gross simplification because this is not my area of expertise, but because dna changes over time, A is "more similar" to B than to C. being "more similar" generally increases the probability of being able to mate successully.

remember we're not takling about parents mating with thier children, we're talking about generations. problems due to "inbreeding" are not caused by general similarity as i understand it.

by the way, i'm not trying to convince you that it's true, i'm trying to convince you that the basic conceptual problems you have with it are not valid.

[Skidoo]

[ QUOTE ]
because dna changes over time, A is "more similar" to B than to C.

[/ QUOTE ]

The DNA can't somehow coordinate its changes to retain fertility WITHIN each generation while at the same time producing infertility BETWEEN generations. What do you suggest as an additional mechanism, remembering the objections I have already raised?

[Sephus]

[ QUOTE ]
And yet again, that's only a partial answer.

Now you have to account for the lack of a similar degradation in mutual fertility BETWEEN MEMBERS within the successive generations.

[/ QUOTE ]

i thought of a better way to say it. you seem to be saying that A->B becoming a lower percentage of success over time is implied by the hypothetical. it isn't.

the probability of success for A->B could even increasing over time and it would still be the case that pA->B is greater than pA->C with p going to zero as the gap gets bigger.

[MidGe]

[ QUOTE ]
If that were true, you would repeat the argument here, not to mention provide examples.

[/ QUOTE ]

Thanks, for allowing me to put it forward again:

Read Dawkins' Climbing Mount Improbable it makes mince meat of your silly arguments and lack of understanding.

Your arguments are shallow and naive. Tell me where Dawkins' book errs. Of course that would require you to read it and although it is a vulgarization it is probably beyond you. [img]/images/graemlins/smile.gif[/img]

[Skidoo]

What mince meat? Please be specific.

[Sephus]

[ QUOTE ]
[ QUOTE ]
because dna changes over time, A is "more similar" to B than to C.

[/ QUOTE ]

The DNA can't somehow coordinate its changes to retain fertility WITHIN each generation while at the same time producing infertility BETWEEN generations. What do you suggest as an additional mechanism, remembering the objections I have already raised?

[/ QUOTE ]

for one thing when you say "retain over time" you're thinking of when B becomes A, etc., and when you say "produce over time" you're comparing a particular A to a particular C.

[Alex-db]

[ QUOTE ]
[ QUOTE ]
because dna changes over time, A is "more similar" to B than to C.

[/ QUOTE ]

The DNA can't somehow coordinate its changes to retain fertility WITHIN each generation while at the same time producing infertility BETWEEN generations. What do you suggest as an additional mechanism, remembering the objections I have already raised?

[/ QUOTE ]

I haven't read that book, but I guess it says something like this, since it seems fairly straight forward:

Assume the parents are representative of an 'average' of the offspring. So 90% reproductivity with the parents means an average of 90% with each other as well. Say the true range is 80% to 100%

Since reproducing requires reproduction, in this question of inheritance it is only sensible to consider the members of a generation who actually reproduce.

Therefore:

When considering a generations' parents, the reproductive % between those parents appears to tend towards 100%, even though the range within that generation was 80-100% and had a difference from its parents of 90%.

(THE ONES THAT COULDN'T REPRODUCE DIDN'T REPRODUCE!)

This no logical basis for expecting reproductivity within a generation to reduce.

This is actually beautifully intuitive if you take a moment to understand it. The simplicty is what makes evolution almost certainly inevitable.

[Hopey]

[ QUOTE ]
When considering a generations' parents, the reproductive % between those parents appears to tend towards 100%, even though the range within that generation was 80-100% and had a difference from its parents of 90%.

(THE ONES THAT COULDN'T REPRODUCE DIDN'T REPRODUCE!)

This no logical basis for expecting reproductivity within a generation to reduce.

This is actually beautifully intuitive if you take a moment to understand it. The simplicty is what makes evolution almost certainly inevitable.

[/ QUOTE ]

It *is* beautifully intuitive if you take a moment to understand it...as long as you don't believe accepting it constitutes a sin. That's where Sharkey/Skidoo's hang-up is -- he *can't* accept evolution, as he believes accepting it would go against his religion's teachings. So he fights tooth and nail to ignore the evidence, and keeps moving the goal-posts so that he never has to admit that he could be wrong.

There can be no other explanation as to why he continues to be so obtuse.