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Breezy " What I remember learning is that ...."
Well, then now you have learned something new. As you see, there is no difference between micro and macro evolution but time and the amount of change involved. The underlying processes are the same. We van think of it like a multidimensional random walk process. Even with very restrictive rules for the number of steps it can take at once, given enough time the process will visit the whole hyperspace, so it can wander really far (theoretically infinitely far) from its starting point.
All I've stated in regards to the micro vs macro distinction is that it is not a false dichotomy, specially not one motivated by Christian propaganda. The underlying processes are the same, but not the things affected by it. One thing does not imply the other. When it comes to macroevolution, almost all supportive evidence is restricted to the fossil record and whatever information one may extract from it.
From my perspective, to demonstrate that macroevolution is possible, would require taking an organism and manipulating it's descendents until it crosses genus and family boundaries. From a bee to a fly for lack of a better example.
The walk process may wander infinitely far, but there's an infinity of variations between a bee and a fly. There's currently 20,000 known species of bees, but the mind can easily conceive of a billion more. It becomes something of a genetic Zeno's arrow.
John 61X Breezy,
Bees and flies evolved from a common ancestor. There is virtually zero chance of a modern bee evolving into a modern fly. So, your example is not good. It assumes a specific target! At the point in time when the common ancestor between bees and flies lived, that population branched off in two directions, and by further branching we arrive at modern flies and bees.
Evolution above the species level is well documented. In some cases it can even be observed within our lifetime.
Then do you view taxonomy as ever shifting upwards? What we call species today, will be supplanted by a subcategory and a sub-subcategory, until the word species becomes indistinguishable from kingdom?
If evolution above the species level has been observed in our lifetime, how has it been different from my bees to flies example?
It's kind of like a growing bush. The divergence of little twigs might someday be the dividing point of large branches. The larger branches of today's bush would become even bigger branches.
Not "if" but "has." Read the literature! Your bees to flies example is nonsensical. However, if you are talking about how far apart bees and flies have diverged from a common ancestor, the result of many tens of millions of years or more, then you would be disappointed. 30 or 40 years of evolution can, in some cases, give you good species in that they no longer can interbreed, but they aren't going to look dramatically different.
Then you're talking about speciation when you bring up sexual isolation; which by definition is evolution at the species level, not above it. Which brings you back to my Zenos arrow, you can create a billion more species of bees, and never get closer to a fly.
Sexual isolation is the first step to define a species (in sexually reproducing ones). Now after you get there, these two species can keep on diverging from each other. For example, in fish, one of them can start to develop stronger fins, that would lead to legs and the other might go into developing shorter harder fins to swim faster. As the process of change does not end, practically any thing that can emerge from an already existing structure, can happen. As you say, you can go forever creating bees, but you can once in a while, you can create bees that look less like bees, and if that has adaptive value, they can keep changing until they look like flies. Of course, the higher the differentiation, the more time and the less often it happens; that explain why there are millions of species but less families, even less orders, etc.
This will happen unless there is a mechanism that stop these small changes to happen and to add up to a big change. As nobody as ever theorized or found a biological mechanism to achieve that, there are not limits about how much differentiation can happen. As I said before, you can morph the face of person into the face of a dog by making small smooth changes, it is the same evolution does.
Breezy : "The underlying processes are the same, but not the things affected by it"
Can you explain what you mean?
"When it comes to macroevolution, almost all supporting evidence is restricted to the fossil record "
Fossil record offers just by itself a very powerful evidence for macroevolution but it is not the only one, taxonomy also suggests the macroevolution path and DNA studies also support and agree in general with both taxonomy and that fossil record so macroevolution has serious support. The fact that intermediate species like Tiktaalik roseae were found based on the predictions of macroevolution, using DNA and taxonomy, validates the theory. Making a testable prediction is the ultimate proof a scientific theory can offer.
"From my perspective, to demonstrate that macroevolution is possible, would require taking an organism and manipulating it's descendents until it crosses genus and family boundaries."
That is your opinion but not that of the overwhelming majority of biologists. Following your way of thinking, continental drift cannot be proved unless we take the continents and move them replicating what happened during geological ages, as the geological and biological evidence would not enough and the GPS measurements we do only show millimetric movement which in no way can move Antartica from the place it is said it was to where it is now. In the same vein, galaxy or solar system evolution will be unproven until you can replicate that in the lab. It is an extreme and illogical position as there are many phenomena that cannot be replicated in the lab in any logical time frame.
On the other hand, recent finds with Darwin finches have shown, through observation, that a new species can arise in a few decades. That makes a very strong case for macroevolution as it greatly reduces the time required for bigger changes to occur.
Lastly, science does not ever find "the ultimate truth", but just our best approximation to it. Theories are surpassed and new ones arise and maybe one day a newer, wider theory will encompass and incorporate biological evolution like relativity theory encompassed and incorporated Newtonian gravity. However, right now, there is not more logical and better-supported theory to explain the diversity of the biological world.
"That is your opinion but not that of the overwhelming majority of biologists. "
Yes but John believes he's right, and is basing this on his faith that the biblical creation myth has some esoteric truth in its absurd allegory.
It's a no brainer really....
Excellent post, but id qualify your remark on relativity before every bat shit crazy creationist starts claiming Newtonian theories were proved wrong rather than just amended to improve our broader knowledge.
It goes like this " So science was wrong then and right now"?
So science was wrong then?
So science is unreliable then?
So why do you believe in evolution then?
And on and on they go until they're equating religious faith with acceptance of evolution. The irony is lost on them.
Well, I think Breezy is smart enough for not to say something like that. However, I was careful to say "to incorporate" instead of "supplant" to avoid the misunderstanding. (Not that many creationist will pay heed to this choice of words but well...) (edited to correct misspellings)
Ask him how many scientific facts he denies that don't in any way refute any part of his religious beliefs. If he's smart he can't fail to see the bias a 'none' answer indicates. Since I have been here he has refused to even acknowledge the question. What do you infer from that? Smart enough to see what the question means, but yet refuses to answer. He once started several threads entitled slavery, all trying to claim the bible denounced slavery, and in every single one of them refused to discuss any biblical texts that specifically mentioned slavery, claiming they were "irrelevant" to his point.
" It is an extreme and illogical position as there are many phenomena that cannot be replicated in the lab in any logical time frame."
The difference between expecting this from evolution and not galaxies, is that we can manipulate genes and not stars. Your objection about doing so in a logical time frame is invalid. Vast time scales only matter when life is rolling dices with organisms. We not only know the genome of a bee and a fly, but are getting better at manipulating them. There's nothing in the way of knowing how many and which variations will turn a bee into a fly; and then going into a lab and testing them.
We even have plenty of transgenerational studies done by psychologist. The psychologist himself doesn't live long enough to see the results, and the next generation takes over the study. There's no reason why geneticists can't do the same, if for whatever reason it takes longer than a single lifetime.
We are just scratching the surface of the genetic code so manipulating it to re-create a new taxa is not within the reach of modern genetics. It is almost as hard as manipulating a galaxy right now. You just have to realize that every organism that has ever roamed Earth is a mutant, an experiment, so the number of changes that the DNA has gone through to create the present diversity and all the possible paths followed to arrive here for just one species is too vast and with so many extinct ancestors, we cannot easily re-construct the time-specific sequence of changes for any species. It is not a cooking recipe.
However, there have been some manipulations, (very elementary ones) that have achieved changes which could classify as a new species. Scientists have been able to produce chicken embryos with an dinosaur snout by altering its genes. If there is an animal like a chicken but with not beak but teeth, it would be a totally new taxon (Dinosauria perhaps?) There are ethical limits to this kind of experiments so they did not allow the embryos to hatch though they thought it could have been viable. It is another proof that macroevolution can happen.
However, if you are not convinced, you can use your own money to fund these experiments (though I doubt thee is money enough anywhere to get them to the level you hope to achieve). Biologists have a theory now that is able to offer testable and tested predictions. That is the most you can hope for a scientific theory and there is nothing that can even touch it right now.
I suppose I'm just not as pessimistic about our ability to do certain things.
My prediction is that the more changes an organism undergoes, and the more it pushes it's genetic boundaries, the closer it gets to disease and disorder. So far, the medical field appears to make a decent income on this prediction bring true.
Breezy; It is not being pessimistic but realistic. However, those chicks with saurian snots will be a totally new taxon, won't they? and they underwent just a tiny change in their genome
"My prediction is that the more changes an organism undergoes, and the more it pushes it's genetic boundaries, the closer it gets to disease and disorder."
Yes, because you are thinking of all changes happening at once on one organism ( that is what Medicine deals with). Your prediction does not work in evolutionary terms. In evolutionary terms, several big changes do not happen at once or even in just one organism. Small changes can also happen in different organisms and then get together in their descendence. Changes are usually small and incremental so they do not render the organism inoperable.
Let's do some hypothetic evolution here. If you compare an axolot and some lungfish or mudskipper you can see that there is not a lot of difference between them, some rather small changes can turn one into another. (Lungfish breath air, and mudskippers use their fins like legs to move on the ground and use their skin to breath).That is clearly proved with amphibians which are fish like as young and rather reptile like as adults. They change rather quickly during their lifetime and are never dysfunctional. This is achieved by just activating or deactivating genes at a certain time and mutations for controlling genes can change the timing and intensity of the activation. Some of these genes can be activated in such a way that metamorphosis happens inside the egg and there are frog and toad species that do that. Some toads cannot even swim and can drown in water. Then if eggs get a harder shell to withstand a drier environment, they can move into total land life. They are closer to reptiles. They will just need a tougher skin with scales to become reptiles and that is not an enormous change either. So we have gone through some small successive changes that do not make organisms unviable from a fish-like animal to a reptile-like animal. We have move three taxonomical classes.
It is not impossible at all.
I'm not sure I agree with the big vs small changes distinction; that seems to suggest a threshold for how many changes can occur at once before causing damage, and as long as the changes remain small and below that threshold there's no issues. Sickle-cell anemia is caused by a point mutation, which is as small a mutation as you can possible get.
In terms of metamorphosis, a change definitely does occur, and they definitely go from fish-like to reptile-like. However, I wouldn't be surprised if the mechanism that allow that to happen are not synonymous with what occurs in evolution. I say this partly because that also seems to be the case when people use fetal development as a sort of crystal ball for how evolution occurs. The genes that are being activated and deactivated in metamorphosis, are probably specialized for that change. Meaning that without that specialization, it might not happen. So again, as unrealistic as you may think it is, thats a hypothesis that needs to be tested directly.
You need to read more about evolution. Big changes come to happen as the result of the accumulation of small changes. Now, there is chromosomal mutation, when a whole or a section of a chromosome is changed (inverted, deleted, fused, etc) these usually causes bigger changes and not always are deleterious. Some plants even duplicate all of their chromosomes and still prosper and all the time viruses are inserting their genetic codes into other species, even moving genes between species. We humans have a lot of viral DNA ( around 5- 8%). What do these genes do is been studied but it offers a very quick way to introduce new information into a genome. Again you are equating changes in one individual to changes in time in a population.
Each of us carries 60 mutations and we are all "normal" so, as you can see, you can carry many mutations and not even reflect on your general functioning but some of these mutations might prove beneficial or damaging if there is a change in the environment. Each of us is an experiment with about 60 changes to our genetic base. Other organisms carry many more than 60.
In respect to metamorphosis: It is really simple to visualize a mutation (or happy lucky group of them, or a viral DNA intrusion) that will keep the embryo stuck in the egg until metamorphosis occur and that mutation to spread in a population. However, the purpose of the example was to show you how there can be incremental small changes that lead to a very different morphology ( a big change) without making the organism non viable.
In any case, you have many opinions but not a model of a mechanism to stop change after a certain number of generations have been changing so as not to diverge "too far" from the original. May be you should try to find that mechanism and go get you Nobel Prize. Meanwhile, evolution is the best explanation for the diversity of the natural world. Do you have another option that can be backed by facts and a biological mechanism?
More Nobel Prizes lol.
I'm curious about these 60 mutations you say we carry, and their effects. Particularly because I've heard theories on death and aging, which attribute them to the accumulation of genetic problems which slip past the filter of reproduction. When people die before reproducing, their genetic problems don't mix into the population. But genetic diseases and disorders that show their effects after reproduction, infiltrate our species, and stab us in the back later in life.
So what are those 60 mutations doing?
Breezy : Most of the time, these mutations do not do anything you can notice. For example, people who are immune to the HIV virus
(about 10% of people of European origin if I remember correctly) carry a mutation that changes the shape of a protein in the cell membrane. This protein is in the place where the virus latches on in order to enter the cell, so the virus have trouble invading the cells and the immune system can kill them. Nobody knew of this mutation until the VIH epidemic started, but now these "mutants" have an advantage. The interesting thing is that studies have shown that, back in the 14th century only 1 in 20,000 people had that mutation so its frequency has increased dramatically. It seems that this mutation protected against the plagues that decimated the population there. Is a clear example of evolution.
Note: the 60 mutations are not just 60, there are many more but each of us has around 60 out of the whole lot. Many people do not have the same group of mutations.
"More Nobel Prizes lol."
I think you mean "NO" Nobel prizes lol. At least not for superstitious guff like creationism pretending it can validate it's myth by denying scientific facts that refute it.
"I'm curious about these 60 mutations"
I'm curious what objective evidence you have that we were magic'd into existence in one go in our current form? Also why you think the deity you choose to believe is real thinks it's "own image" is accurately reflected by 96% of Chimpanzee DNA?
Now back to Campbell's Biology, do you agree with it that species evolution trough natural selection is a valid scientific theory. or are you only cherry picking the bits you like, same as your biased "interpretation" of the bible?
Also it's a timely reminder that your unabashed evasion is as always not going unnoticed, so here are some questions you have slithered away from / have no candid answers for...
Q1) Does it (text book your citation) say macro evolution occurs over less, more or the same timescale as microevolution?
Q2) Are you claiming the text says they occur on the same timescales? Could you quote that please, and offer some other sources that agree.
Q3) Also if it agrees that speciation occurs why do you deny it? I did ask if you agree with everything in the text book? Otherwise we're back to you using selection bias to cherry picking only the facts that align with your religious beliefs. Am I going to get an answer?
Q4) Could you provide half a dozen citations to peer reviewed research that supports your claim that macro and micro evolution are not part of the same process, but are separate processes, and that timescales are irrelevant?
"I do think there are at least three possible obstructions. "
I don' think you do think , at least not for yourself, but that aside...Does the text book you claimed "has a monopoly on Biology textbooks. " agree with your claim? Any chance of you referencing a chapter and page number with a quote? Can you cite any other sources that support your claim?
"I wouldn't be surprised if more obstacles exist that prevent changes above the species level."
You could try taking a look around at all the different species, there's a reason that Darwin entitled his seminal work the origin of species, and his work has withstood 150+ years of scientific scrutiny.
Buy the textbook, I gave you the Amazon link.
You cited it not me, why on earth would I need to buy it, if you were telling the truth then the claims would be reflected by mainstream science, and they're not are they?
I have not disagreed with scientific facts, or even disagreed with the textbook, just asked you to evidence your claim, and as usual you wriggle and thrash about refusing to offer evidence. You claimed the text book had a monopoly on biology, yet the claims you made are at odds with established facts, which is where we came into this.
So I'll try again then, does the text book you cited agree with you that there are valid objections to macro evolution? Or that macro and micro evolution are separate processes, rather than different aspects of the same process separated primarily by timescales? Or that taxonomies are inaccurate? Or that timescales are irrelevant to micro and macro evolution?
John: Does Campbells Biology teach Darwinian Evolution as a valid theory?
John: Did you study biology further than 101/102?
Depends what you mean by further. I took a course in genetics and another in microbiology. That's about it within biology.
That's odd, you claimed that was an unintelligent question yesterday?
So do you agree with the text book? Or do you cherry pick what you accept as true based on your a priori religious beliefs?
So the text book you claim has a monopoly on biology doesn't reflect your opinion, quelle surprise. As I said you are cherry picking which bits of it you agree with, just as with all else where you filter everything through the sieve of your religious beliefs.