Discussion in 'Biology & Genetics' started by garbonzo, Jun 4, 2013.
It produces change and nature selects the best adaption or traits.
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Actually I am not fond of the term Natural Selection. It suggests an act of selection, but the opposite is true. Natural selection is a passive function; those who survive to reproduce have been selected, by default, each in there own niche.
For an odd example of natural selection; The silvery salamander is an interesting species, all offspring are exact clones of the mother.
Darwin used the term in reference to artificial selection, after pointing out that crops and livestock had been modified over generations by the deliberate selection of breeding pairs. Artificial selection is one of the facts dismissed by Creationists, although it probably has forced their hand on admitting to microevolution.
As for imposing order in allele frequency, it's a variation about the mean, and the studies tend to show Gaussian distributed variation, which is the natural distribution for populations (hence "normal distribution"). It's slightly counterintuitive - at first blush the uniform distribution would seem to be the default, but with just a little analysis we find that this is not the case.
That being said, there is a kind of order that arises by the splitting of one Gaussian distribution into two populations centered about different means. It's just not meaningful to say which one is "more ordered" other than to say perhaps that one has a lower variance, but that's just a raw statistic, not anything meaningful as far as the ability to dominate a niche.
Another way of thinking of order from the standpoint of statistics is to note that the overall tendency is to continually diversify, and the tendency to perpetually open new niches can be seen as a sort of disorder.
The politics of this is that the Creationists have seized the concept of order, and wherever they see in come up in science, that attribute it to God. Usually this is in the context of entropy, which has become a linchpin of Creation Science. But for all of their forays into that subject they will never properly treat the topic of interest as a closed system, so the analysis is never even close to being valid.
Statistics is really the downfall of all Creationism anyway. The fact of randomness at all completely dismantles the notion of intelligent design. It was Darwin's reflections on the fact that the Darwin's finches were created after the Galapagos rose from the ocean floor which he knew would spell doom for the theory of special creation. It would require God to continually come back in and intervene in genetic selection, and in niche creation itself, just to perpetuate new instances of not-so-special creation. After all, for what purpose would 14 species of Darwin's finches have been placed on remote islands unreachable by early humans? Just so Darwin could come along later and cause the schools to eventually have to teach the kids that God may not have intended things to be the way they are?
Long before Einstein would wistfully opine that God does not play dice, Darwin had already shown that there was a huge casino out there, and business was booming.
Thank you for that explanation.
True, but in view of the fact that some 90% of all species have disappeared, perhaps this "complexity" (variety) is what allows some species to consistently remain the survivor and assure offspring.
You're right about the high rates of extinction. Some estimates place it around 99%. It's one of those things that's impossible to nail down with certainty since there's no accounting for most soft-body organisms in the fossil record.
Variation is the life of evolutionary success, that's for sure, too. It's really remarkable that we can toss this idea around - is it more or less orderly if the mean of one distribution shifts right or left, etc. - and it's a politically neutral question. It's just observation and a discussion about how we might categorize or classify one parameter or another. But allow the creationist into the discussion, and the polemic begins and objectivity loses its creative mind. It's literally insane to politicize science, but, at least where the battle lines have been drawn, there is almost no choice.
I can remember the first time I noticed that biology texts started reserving a page or two to explain the origins and history of the polemic to students. It's a distraction - something that belongs in a class on Government or Sociology. But now it's fully embedded in the life science classes even in small towns in Appalachia. It's really remarkable that Creationism has hung on as long as it has but of course world views tend to change on the scale of generations.
Back to statistics - it's really the understated piece of evolutionary biology during the polemic, but it's the huge component of "cause" and it's the whole basis for "binning" species. The only reason to declare that a particular fossil belongs in one bin or another - or whether a new bin has to be opened - has to do with the paleontologist's interpretation of the statistical evidence that's being studied.
Order vs complexity is also an interesting question. It forces us to decide what we mean. One way to look at this is that when the genome gets longer there is greater probability that the variance in allele frequency can widen. But there's a counterintutive side to this, too. For example, we might tend to think that later species would have longer genomes, or that even humans should have the longest genome since we think of ourselves as the pinnacle of nature, and in many ways the most complex. Yet that's not true of our genome - in fact an innocuous looking plant has the longest known genome and therefore the greatest "complexity" from the information science point of view. Of course this may change tomorrow due to some new animal found in a cave, or maybe a glob of slime found in some stagnant pond.
The other crazy thing about complexity, from the perspective of molecular genetics, is that humans are so much like a banana, or a yeast. It just goes to show, no matter how many ways the Creationists keep oversimplifying - that the truth is stranger than fiction. And all the more reason to keep them out of the classroom, I might add. Please Register or Log in to view the hidden image!
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The creationists keep a stable of well-educated science students on hand for these encounters. 30 years ago we attended a debate between a real scientist and one of these so-called "creation scientists." These are the real evildoers within the movement. They actually know that they're preaching antiscience, but they've been so thoroughly co-opted by their churches that they lie in order to bring the uneducated masses into their religions.
The creationist very carefully picked a few samples from the fossil record that appeared to prove his point, without letting anyone see the thousands of others. His "peer reviews" were primarily undergraduate papers from unaccredited fourth-rate church-run universities like (now mercifully defunct) Ambassador College. And of course he was an expert communicator so he was very persuasive. As I've noted many times, real scientists tend to be absolutely shitty communicators so it's not too hard to shoot them down.
Fortunately this took place in West Los Angeles near UCLA, so he didn't win any converts.
Especially since the leaders of all major religious denominations (including the Pope himself) have said in public that the legends of religion are merely literary metaphors that, like all metaphors, are simplifications to help us understand reality. Jesuit universities have been teaching evolution for decades, and plate tectonics since it became a canonical scientific theory. They don't believe that it serves any useful purpose to teach intelligent adults that the world was created in six days with the continents in their current spots and the ecosystem just as it is today--except for the fact that there was no violence so sharks and tigers ate vegetables and flowers. I've always wondered how big their stomachs must have been in those days, in order to host a multi-chambered bacteria culture to digest all that starch, like cattle and elephants.
Isn't this something that is true overall, but not at the species level? Notwithstanding that one plant, don't animals as a kingdom have longer genomes than plants, which are longer than algae, which are longer than fungi, which are longer than archaea and bacteria? (I don't know which of those last two kingdoms is regarded as the more complex. I also don't know whether I have algae and fungi in the right sequence of complexity.)
In any case, that organism with the longest genome is, at least, a plant, not a bacteria!
Don't we share something like 40% of the DNA of a banana tree?
It's as though (like many people) they're misinterpreting Occam's Razor. They seem to take the popular misinterpretation, "The simplest solution is usually the right one," rather than the proper meaning, "Always test the simplest solution first, in order to save yourself a lot of time and effort in case it turns out to be right."
Since creationism is a major problem, it obviously should be discussed in schools. But it belongs in civics or sociology, not biology.
The main reason the simplest solution is best, is it allows more people to participate in the discussion. The most complex solution puts understanding in the hands of only a few, who then tell everyone what to think. This is good for those who wish to lord of the herd, but it removes the checks and balances of diverse options and tends to degenerate to dogma.
Water is important to evolution but its impact is not fully included in the complex dogma. Using the basic principles of evolution, water is the environment for natural selection at the atomic and molecular level.
If we had animals, evolving within the polar regions of the earth, these environmental conditions set constraints which will be reflected in the direction of the selection process. If they migrated there and evolved from that point we would expect warm fur will be selected. At the level of the molecules that need to evolve into life, these have to deal with the constraints set by water.
We do have animals evolving in the polar regions you dolt!
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I just wanted to say thanks Aqueous ID ...(ID is that Intelligent Design???)
So a longer genome could be a disadvantage as the cell has to reproduce so much baggage. Even though I think it might actually be an advantage, with having the genetic code for variety already written. It is just a matter of switching on a redundant bit on when needed rather than going through the problem of redesigning a protein.
But, Aqueous ID, did god not separate the waters from the firmament? You can't now say that everything is waterbased.
Hydrogen is the most abundant element in the universe. There never was a separation of water from the firmament. The bible was wrong, not science.
The galaxies in the visible Universe are flying off in all directions, and so even hydrogen will become as scarce as hen's teeth in time to come.
The only galaxy (The Milky Way) remaining in our view will gradually be reduced to a single black hole and hence there will be nothing left at all other than the dark matter, and oodles of empty space.
What will become of the dark matter?
Change is not the same as increase in complexity, which is what you claimed.
True, a better way to say it would have been; evolutionary change "yields an increase in efficiency". This might even come from simplification rather than greater complexity
The below chart shows that older simpler organisms seem to have required more individual building instructions than later more complex organisms which managed to combine certain instruction into a simpler form (instead of 2+2+2+2+2, an instruction 2 (x5).
The most general way to look at the impact of water, on evolution ,can be seen connected to mixing water and oil. If we mix these and then add energy by shaking them, we can increase the system entropy/disorder to form an emulsion. This increase is disorder/entropy will not last, since this situation creates surface tension within water thereby adding potential energy to the water. This aqueous energy will need to lower causing the organics and water to phase out thereby lowering system entropy. Free energy is a combination of entropy (disorder) and enthalpy (chemical energy), with the chemical energy increase within the water, due to entropy, getting stronger when water interacts with carbon compounds.
As an example, RNA can form a single helix while the DNA only forms a double helix. This sense of higher order by evolving from RNA to DNA, is connected to the water. DNA has more reduced groups, compared to RNA, therefore exposure of the DNA, as a single helix, will increase the aqueous surface tension much more than RNA. Although this separation of the DNA is in the direction of higher entropy, the energy/enthalpy increase in the water, and the need to lower this energy, will force the double helix to form even if this lower entropy into order.
If you look at the direction of evolution, from RNA to DNA, this progression involved adding more reduction potential to the RNA template material; the RNA become more reduced in the sugar and bases. This evolutionary change follows the direction of adding more carbon based energy (reduction), relative to water, thereby forcing the hand of water; water will push this carbon into order. If we were to anticipate the future of the DNA, we would expect further reduction, such as methylation and maybe even ethylation, causing the DNA into even tighter order.
Interesting that you are looking at future evolution. If DNA gets too tight it might become too difficult for the enzymes to split in the replication process. Therefore multiplication stops and evolution stops.
Is this then the self limiting step.
"Best", in a "solution", has absolutely nothing to do with whether you like being told what to think.
Complex and difficult understandings may indeed degenerate to dogma - simplistic mistaking doesn't need to degenerate, to suffer that fate.
This is a good intuition, but I would explain the logical outcome differently. If we make the DNA double helix tight, by chemically reducing the DNA, to increase the surface tension with water, we can eliminate random reactions on the DNA, and make life more ordered.
As an analogy, say we had a door with the lock barely touching the strike plate (early loose DNA). This allows the door to easily open in many ways. One can lean on it, the wind can blow it open, other doors opening and closing can cause the internal pressure to push it open. This allows the cat to escape. But as we tightening up the lock (push of water) now it is not easy to open the door; involves keys. The future will require stronger enzyme keys, with the DNA being less vulnerable to chaos and chance. Change will involve locks and keys.
This lock and key arrangement is common to enzymes too. Enzymes would have been expected to be much less specific in the old days of evolution. An exact lock and key was the inevitable result, because of water, so there was less breaking and entering by chance. This is also due to the oil and water analogy.
Proteins have unique folds, which may not have always be the case in the old days. What is cool about the unique fold and therefore the specific lock and key, is once the door is open by the key, the potential in the local water increases because the innards are exposed and surface tension raises it ugly face again. This is like the spring on a door that slams the door, locked.
But how does the DNA adapt ?
Does the DNA become though less adaptable ? Is my question
DNA has no "surface tension with water". Chemically "reducing" DNA, whatever that means, does not make its standard first order double helix structure "tighter", and any higher order structures are mediated by proteins, not ambient water. An imaginary "tightening" of DNA coils would hypothetically interfere as much with repair mechanisms as anything else, rendering such events as radiation damage more rather than less effective at burdening the DNA with "random reactions".
"Tightening" the spiral in a stretch of DNA will not increase the "orderliness" of life, regardless of its effects.
The notion of "life" becoming "more ordered" is meaningless anyway.
As far as contributing to a discussion of the denial of evolution, one awaits the connection. It seems to have more promise than a discussion of planetary orbits in pre-Galilean terms, at least.
I can't comment any more for it is way out of my field.
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