A Discussion of Evolutionary Theory

[mrhnau]

Had another comment related to the last post, with regards to "Invention". Over the past decade or so, many novel genes have been added to various crops. Most of Europe has banned their consumption/import, and the release of some organisms into nature has been a hot topic of debate.

Do you consider this "evolution"? If so, what do you think of man originated evolution? 1000 years down the road, do you think we will have dramatically altered the biosphere?

MrH

 

[Makalakumu]

In any regards, macro-evolution (the point of this post?) lacks repeatability.

You can't test macro-evolution with a test tube, but you can test it with comparitive anatomical studies. These studies are repeatable in the sense that between different species, the same principles can be applied.

 

[heretic888]

One thing that strikes me about Post-Darwinism is that so much of it seems to be about retooling the idea of "natural selection".

Based on what I've read from the aforementioned research, I'd have to disagree with this assessment. The post-Darwinists don't seem to be as interested in redefining natural selection as subsuming it within a broader theoretical context.

Classical natural selection stated that the environment selected certain organisms who were the best adapted. This caused small changes in the morphology of populations. Over time, these small changes built up and eventually turned into big changes.

My understanding of traditional neo-Darwinism is that random genetic variations (i.e., mutations) is what causes incremental changes in a species over time. Natural selection merely 'eliminates' the variations that are less adapted for a given environment, thereby ensuring the better adapted variations will be the ones that contribute to a species' morphology.

Post-Darwinism seems to be challenging the assumption that these gradual incremental variations can lead to speciation, instead offering alternative explanations (such as self-organization theories). Natural selection itself, however, never seems to be challenged as an explanation for which genetic variations of a given evolved structure will be passed on.

When Eldridge and Gould published their theory of pucntuated equilibria in 1973, the paradigm was challenged. They said that constant change was not observed in the fossil record. Rather, great amounts of change over short periods of time rightly described the data. "Natural selection" wasn't really addressed here, only the time component.

Ok.

Now, "natural selection" is being addressed. Post Darwinism, IMO, is about asking what exactly happens with "natural selection." Is it a singular phenomenon or is it composed of many mechanisms genomic change.

I think you're meaning "random variation" here, not "natural selection".

Natural selection describes the selection pressures the environment presents toward any given evolved structure (and therefore tells us the likelihood of it surviving in that environment). It doesn't tell us anything about how that structure evolved in the first place.

Random genetic mutation is the traditional explanation for how newly evolved structures are "created" (pardon the pun). However, the post-Darwinists challenge this explanation (and rightfully so).

Either way, the simple explanation presented in classical Darwinism still holds...the environment selects individuals that are best adapted.

Post-Darwinism, from as far as I can tell, does not challenge the validity of natural selection as an explanatory principle for adaptive inheritance.

For instance, one theory I read about stated that the genome selected traits to fit the environment via a feedback loop. "It" accomplished this by horizontally transmitting endogenic retroviruses formed from junk DNA. This transmission of traits incorporated new DNA into a "host" and the subsequent morphologic was expressed vertically. Ultimately, this would result in the creation of not only genetic/phylogenic diversity, but speciation.

Yup, pretty much.

Laterz. :asian:

 

[heretic888]

In any regards, macro-evolution (the point of this post?) lacks repeatability.

So, if I understand you correctly, you're complaining that speciation can't be "forced" or "controlled" in a formal laboratory setting? No offense... but, well, duh.

Go with Upnorthkyosa on this one. Just because something can't be done in a test tube doesn't mean it can't be replicated. Replicability in science refers to methodological replicability (i.e., if I follow the same procedure you did, I should come across the same or extremely similar results).

It doesn't mean you can "force" whatever phenomena you want to happen in a lab -- and, if it can't be done in such a way, then whoops! Bad science!

By your criteria, the research of paleontology or history as a whole can't be "replicated" either. This will come as news to most paleontologists and historians, of course.

Evolution starts having problems when discussing origins. There are a few other sticking points.

Post-Darwinist research is addressing many of these objections, which have historically been used as political weapons by proponents of Creationism and Intelligent Design to push their respective agendas.

To use but one example, Sheldrake gave arguments concerning how the statistical improbability of certain evolutionary emergents (including the earliest single-celled organisms) is more or less negated when you give up a paradigm of random variation to explain all forms of speciation. Self-organization theory and non-random mutations make any such "origins" much more plausible.

Laterz. :asian:

 

[heretic888]

Do you consider this "evolution"?

Yes.

If so, what do you think of man originated evolution?

All "man originated evolution" has its basis in "nature" (or else it wouldn't be possible). The delineation between the two is largely a matter of conceptualization.

1000 years down the road, do you think we will have dramatically altered the biosphere?

Given current trends, yes.

Laterz. :asian:

 

[heretic888]

If you want, we can start another thread to get into that one.

Continued here.

Laterz. :asian:

 

[mrhnau]

So, if I understand you correctly, you're complaining that speciation can't be "forced" or "controlled" in a formal laboratory setting? No offense... but, well, duh.

Depends on what is meant by macro I suppose... can certain traits be expressed or repressed? yes. Seen some fascinating work with D. Melanogaster (fruit fly), where they were able to get wings to grow out of their head. Strange, but interesting. Insertion of genes across species could be considered macro. Many things are bioenginered now. Guess I'm thinking more along the lines of turning a chicken into a cow, along that lines

It doesn't mean you can "force" whatever phenomena you want to happen in a lab -- and, if it can't be done in such a way, then whoops! Bad science!

By your criteria, the research of paleontology or history as a whole can't be "replicated" either. This will come as news to most paleontologists and historians, of course.

Telling me history is a science now? Whats next? Want Foreign Languages to be science? Literature? Everything? Non-scientific fields should not be held to the Scientific Method.

Is science "forcing"? There is another word for forcing, its called expirementation. Can't explore meta-evolution on a large scale, so you play with it on a small scale (wings out of the head). You can't start a new star on Earth, so you work with particle physics on an accelerator, and see what happens on a small scale. you "force" things. Can all things be treated this way? Doubtful. However, you learn much about the whole by studying the pieces in great detail.

To use but one example, Sheldrake gave arguments concerning how the statistical improbability of certain evolutionary emergents (including the earliest single-celled organisms) is more or less negated when you give up a paradigm of random variation to explain all forms of speciation. Self-organization theory and non-random mutations make any such "origins" much more plausible.

Laterz. :asian:

Some of the problems... how does a permeable membrane spontaneously form? Its pretty much the basis of single cell origin. Needs to be water permeable, but be able to control certain conditions (ion pumps, nutrient passing across barrier, pH gradient, availablity of usable energy). Could such a lipid membrane spontaneously occur? Possibly. At the same time as replication processes emerge? Say a satisfactory membrane emerges. The "cell" would certainly die over time, unless in that time frame a satisfactory replication process is conceived.

Replication process... most evolutionary scientists agree that life started with RNA, not DNA. So, assuming RNA did automatically come about, there needs to be the proper polymerase to replicate. Such a protein/nucleic acid structure needs to be developed somehow, spontaneously? And you get lucky enough for such an apparatus to be developed inside an appropriate single cell organism? Need the apparatus for lipid formation for the new cell, and a method for cell mitosis, otherwise cell death will end the cells existance. Sort of along the lines of sexuality spontaneously emerging. Even the simplest of cells that are non-viral or parasitical are quite complex, and require so many proteins and chemical processes to survive. Another interesting debate going on is the minimal set of genes/proteins required for an organism to remain alive, and at this level, what is considered alive.

This way predates speciation, and gets back to the origin of things. To me, I'm more interested in this angle of evolution. Its something I don't hear alot about. Will evoution solve these problems? perhaps... I'm not aware of much conclusive work along this line. If you are, please share. I'd be interested in reading some of it.

MrH