Wholly Natrualistic Alternative To Neo-Darwinism?

[Lowpro]

<snip>

So Darwin supplied the overall view, and Mendel supplied the first notion of genes carrying traits that were passed from parents to offspring.

You're damn well right he did. Darwin proposed the idea of evolution by natural selection SPECIFICALLY stating that traits were varied and inheritable. He proposed the mechanism and gave the theory predictive power. That predictive power has not failed. There has been no change of horses, you just don't seem to make the connection. I honestly have no idea why. Watson and Crick's finding did not invalidate evolution, it validated it and kickstarted microbiology which again only validated it even more. With the findings of variation to be genetic traits it found that mutations occur due to chemistry, and those mutations can provide variation. This is the Cytochrome C neutral evolution part because the mutations themselves ARE being selected for, but it's a fatal selection*; either the change does nothing, or the organism dies to mitochondrial disease. It's this way because Cytochrome C's chemical function is actually "easy" compared to the proteins necessary.

Why does this need to be repeated?! You say I missed your point and I've only addressed it every time. Now we're BOTH spamming... at least mine's not nonsense.

*To be complete, it doesn't have to be "fatal" but if a change in Cytochrome C wasn't neutral then it's very unlikely it'd be beneficial; cytochrome C's function is determined chemically and unless it takes us a different better function I doubt that it could get better without the whole of the ETC changing as well. But if it's not getting better or staying neutral, it's worse. Predictive power of evolution; if the change makes you less fit which by definition means you don't get to reproduce (damn the means of "why")then that variance of genetics in your CytC will NOT be passed on. The very fact that there is variation in the Cyt C of different organisms proves evolution BECAUSE the inherited traits that kept the organism fit (enough) were passed down, JUST as Evolutionary Theory predicts.

There is no changing of horses so your opinion is noted and dismissed on lack of evidence to confirm it. You just don't like it. I've already said this TOO in another thread, so I am glad we're back here again; can't wait to see you make a third thread to be told this again.

 

[bjornart]

Time to first life is irrelevant. Time to last common ancestor isn't.

Sure, but how far apart really are first life and the last common ancestor of bacteria, yeasts and humans? Do we have it down to a nearest hundred million years?

 

[marplots]

I think Patrick's argument is worthwhile because it illustrates a misunderstanding well. The root mistake, as I see it, is that evolution is used to mean any change at all and the only path from there to here. But we know it isn't so.

For instance, you can figure out the age of a star by looking at things like its mass and the ratio of hydrogen and helium -- there's a clock-like mechanism there that has nothing to do with evolution. We sometimes use the word, but not in the biology or Darwinian sense. So we know that things do change with time, even when selection is not happening.

This same process occurs in living things. Mutations come along. The difference between the non-evolutionary change and the evolutionary change is whether or not the change is fixed by survival. A beneficial change that increases survivability will tend to stay and a negative change will tend to disappear.

But what about a neutral change? These aren't acted upon by selection, so they pretty much follow the star analogy and accumulate over time.

But the picture is made more complex because at each step, a mutation may fall into one of the three categories (or partially into more than one). And, there are mechanisms for DNA repair that kick in as well.

You get a sequence like this: drift --> negative --> drift -->more drift --> positive --> drift that extends over a long time. Those organisms that reach a negative spot on the chain get set aside, the positive remain, and everything experiences some drift when that is neutral.

I expect this is too shallow an explanation for the experts, but I'm still hoping Patrick can fit it into his worldview. In a sense, he is right, drift isn't really classic evolution, unless or until selection acts to preserve or delete it. Is that a new "mechanism"? Not really, it's an assumption underlying evolution itself. If you count any sort of change over time as evolution, you get evolving stars, mountain ranges and so on.

 

[Philosaur]

This same process occurs in living things. Mutations come along. The difference between the non-evolutionary change and the evolutionary change is whether or not the change is fixed by survival. A beneficial change that increases survivability will tend to stay and a negative change will tend to disappear.

But what about a neutral change? These aren't acted upon by selection, so they pretty much follow the star analogy and accumulate over time.

I think rigor here is a good thing. Technically, selection only "acts" upon traits that negatively impact survival. In this sense, there are only two categories of mutations: those that impact negatively, and those that don't. Natural selection has no way to reinforce, bolster, or improve those traits that give an organism a survival advantage.

In fact, positive traits sometimes become negative through evolutionary overshoot. Those giant horns may be good for defending your harem, but if they get so big you get stuck in vegetation and starve to death, then natural selection will have "acted".

(The scare-quotes are there to remind anyone not already clear on this that natural selection is not a "force" that determines who lives and dies. Natural selection merely describes the phenomenon where those ill-equipped to live in a particular environment tend to die before having offspring.)

 

[marplots]

I think rigor here is a good thing. Technically, selection only "acts" upon traits that negatively impact survival. In this sense, there are only two categories of mutations: those that impact negatively, and those that don't. Natural selection has no way to reinforce, bolster, or improve those traits that give an organism a survival advantage.

In fact, positive traits sometimes become negative through evolutionary overshoot. Those giant horns may be good for defending your harem, but if they get so big you get stuck in vegetation and starve to death, then natural selection will have "acted".

(The scare-quotes are there to remind anyone not already clear on this that natural selection is not a "force" that determines who lives and dies. Natural selection merely describes the phenomenon where those ill-equipped to live in a particular environment tend to die before having offspring.)

Yes, thank you. It is difficult to extract lay explanations from what is essentially the result of a statistical, mathematical process. I can't do it without emotionally laden words that really don't apply -- positive and negative, for example.

Evolution is much better handled using Markov chains and the language of mathematics (with a nod to biochemistry), but that seems to make it inaccessible. The answers don't satisfy people either. The conversation goes like this...

"How could we have evolved from long extinct mammals?"
"Well, here is one example where the background mutation rate, coupled with the survival rate shows, over time, on this log scale, how a mutation propagates through a population based on breeding rate. Your answer falls out with the math."
"Yeah, but how can random change result in me and that hot chick I'm interested in?"
"Well, it's a statistical measure of population norms, and sexual selection falls out as one of several relevant metrics that shape the overall, chaotic envelope and acts as a strange attractor in a multidimensional space of possibilities."
"Yeah, whatever. Can't you make it all simple and tidy?"
"No."

It is frustrating when the only answer you can give that is true and honest consists of recommending a series of textbooks and a few years of education. And, to make it worse, my education in this is dated and stale. But I understand the impetus to ask the questions. My mistake is assuming people who ask really want to know when they sometimes just want to trip up the whole enterprise because they think they've found a glaring error.

What can we really do except an appeal to authority? The best I can manage is to try to take on the question using the flawed construction of the questioner. I am sad now.

 

[Dinwar]

I expect this is too shallow an explanation for the experts, but I'm still hoping Patrick can fit it into his worldview. In a sense, he is right, drift isn't really classic evolution, unless or until selection acts to preserve or delete it.

One thing experts do is look at n-dimensional fitness space. The higher the organism is in the fitness space, the more fit it is. This actually very neatly deals with what Patrick1000 is talking about, and far more--for example, it's often true that an organism isn't that well adapted to its environment, and the reason is that they are at a local fitness-space high, and any mutation will decrease fitness. It's like standing on the top of an island and trying to climb a mountain on the mainland without getting your feet wet--without some major shift, you just can't do it.

Of course, it has to be kept in mind that all fitness spaces are changing through time (local, changing environments and all), so sometimes that ocean becomes a mountain itself. It actually gets vary complicated, as n-dimensional topography is want to do...Gives me a headache every time I work with it.

Anyway, if the organism is at a level plain in fitness space--in other words, if some trait has no selection pressure--statistical artifacts take over. One such artifact is a molecular clock. Another would be fixation of something for no reason other than random chance. It gets far weirder than mollecular clocks.

If you count any sort of change over time as evolution, you get evolving stars, mountain ranges and so on.

I think it would be safe in this context to limit the term "evolution" to meaninig changes in biology, and primarily changes in allele frequency, through time. In which case yes, neutral selection pressure yields evolution.

 

[Twiler]

Euclid (apparently) said that there was no royal road to geometry.

I think that there is no royal road to understanding evolution either.

 

[Dinwar]

There's no royal road to understanding science. You've just got to slog through it, and admit when you don't know something.

 

[Hokulele]

I think rigor here is a good thing. Technically, selection only "acts" upon traits that negatively impact survival. In this sense, there are only two categories of mutations: those that impact negatively, and those that don't. Natural selection has no way to reinforce, bolster, or improve those traits that give an organism a survival advantage.

In fact, positive traits sometimes become negative through evolutionary overshoot. Those giant horns may be good for defending your harem, but if they get so big you get stuck in vegetation and starve to death, then natural selection will have "acted".

(The scare-quotes are there to remind anyone not already clear on this that natural selection is not a "force" that determines who lives and dies. Natural selection merely describes the phenomenon where those ill-equipped to live in a particular environment tend to die before having offspring.)

The only quibble I have with the above is that it assumes the species we see today derive solely from natural selection. It should be noted that in organisms that use sexual reproductive methods, sexual selection can also "shape" them. The big horns may get you stuck in vegetation, but the harem will completely ignore you otherwise in favor of one with bigger horns. Oftentimes, selection favors reproductive success over mere survival.

The classic example being the gene(s) that cause sickle-cell anemia also providing resistance against malaria. This mutation will cause a shorter overall life-span, but a greater likelihood of reaching reproductive maturity.

 

[godless dave]

The only quibble I have with the above is that it assumes the species we see today derive solely from natural selection. It should be noted that in organisms that use sexual reproductive methods, sexual selection can also "shape" them. The big horns may get you stuck in vegetation, but the harem will completely ignore you otherwise in favor of one with bigger horns. Oftentimes, selection favors reproductive success over mere survival.

The classic example being the gene(s) that cause sickle-cell anemia also providing resistance against malaria. This mutation will cause a shorter overall life-span, but a greater likelihood of reaching reproductive maturity.

Isn't sexual selection just part of natural selection?

 

[AdMan]

Isn't sexual selection just part of natural selection?

I think it is, but within natural selection there are differences between "ecological selection" and "sexual selection":

http://en.wikipedia.org/wiki/Natural_selection#Types_of_selection

 

[Dinwar]

Isn't sexual selection just part of natural selection?

That's my understanding--"natural selection" is a broad category, of which sexual selection is one sub-category.

 

[Lowpro]

Well with evolution you couldn't even "teach" all of it by virtue of it being a theory. You can teach starting at its fundamental concept of Natural Selection which had predictive power. That came first. As Mendelian genetics shows there were obviously inheritable traits that shaped phenotype. As molecular genetics came we learned what genes were and how natural selection acts on the organism which HAS the genes. The genes determine an organism's fitness in its environment and its fitness determines if the genes are beneficial and its selected for* basically.

Not that Natural Selection is an entity, it's just the wording that's commonly used with the understanding that being selected for is evident in population/gene studies.

 

[Dancing David]

It is of course vital to use the correct erm because if you don't use the correct erm people will get all hot and bothered because your erminology is incorrect.

Argh!

 

[Dancing David]

I think rigor here is a good thing. Technically, selection only "acts" upon traits that negatively impact survival.

I disagree, selection happens when traits effect reproductive rates. Negative or positive.

 

[Lowpro]

I disagree, selection happens when traits effect reproductive rates. Negative or positive.

Mhmm. By reproduction rates it's really just meaning "however the genes disseminate through the population" because it doesn't have to be the organism's fitness throughout its life that matters, it's the fitness of the organism's ability to disseminate its genes. It's the selection pressures against the population that can lead to the wide variety we see.

And as important as ever, this is the predictive power of the Theory of Evolution.

 

[catsmate]

How does that article refute Dinwar's claim?

It doesn't.

It suggests that the term is still in wide usage and that while some regard it as incorrect, "publications such as the Encyclopaedia Britannica, use this term to refer to current evolutionary theory. This term is also used in the scientific literature, with the academic publishers Blackwell Publishing referring to 'neo-Darwinism as practised today', and some figures in the study of evolution like Richard Dawkins and Stephen Jay Gould, using the term in their writings and lectures."

The claim that it has been rejected is hyperbole.

As I pointed out earlier the term is not in general use; it is still used by a few scientists and by some publishers.
Interestingly the term isn't used by Wiley/Blackwell except here which is an excerpt from a definition in an undergraduate text written in '96 by a student of Dawkins.
You won't find it used much in scientific journals or by active scientists. It is popular with creationists and IDiots as a quick google shows.

[ I'll concede that the SJG reference somewhat dates the article. ]

As does as the 'Blackwell' one.

 

[AlBell]

It is of course vital to use the correct erm because if you don't use the correct erm people will get all hot and bothered because your, erm, erminology is incorrect.

ftfy.

 

[catsmate]

A lot of times people, myself included, use the terms "neo-Darwinism" and "modern evolutionary synthesis" interchangeably.

Then you are wrong; stop doing it.
Though given the other mistakes you've made this is a small one, but revealing about your intent and sources.

 

[catsmate]

It is of course vital to use the correct erm because if you don't use the correct erm people will get all hot and bothered because your erminology is incorrect.

Have you ever actually studied science? Using the correct terminology is extremely important, it allows other people to understand what you're saying and enables the interchange of ideas.