A question for evolutionists re knowledge of how macroevolution occurs

(Mitchell W McKain) #41

Incorrect. It is an unsolved mystery and the most well known hypothesis is the Yucatan asteroid impact leaving a layer of iridium all over the place. At least hypotheses like this would explain why they didn’t simply adapt to the climate changes. In other words, there is probably more than one cause and an impact could have been a triggering event for more than one these changes to make a more sudden change which many species were unable to adapt to. It was also likely to have been something of a chain reaction, as the loss of plants and animals starved out those species which depended upon them.

(Mitchell W McKain) #42

The flying squid were certainly a surprise to me.

(Stephen Matheson) #43

It’s false in a few ways. Most but not all dinos went extinct, during a mass extinction event that eradicated 3/4 of the earth’s species. There is consensus that the era was characterized by dramatic climate change, but “colder” is too simplistic. Overall climate became cooler but is typically characterized as more chaotic and definitely as “disrupted.” More importantly, I think there is substantial support for the position that ecosystem destruction was catastrophic, leading to complete collapse of entire ecosystems. There seems to be debate about whether ecosystems were already stressed, due to some notable but not singularly catastrophic climate swings. (See first paper below.) But conversely, there seems to be consensus that a catastrophic event, namely the Chicxulub impact, triggered the global collapse leading to massive extinction. See the second paper.

(Roger A. Sawtelle) #44

That is interesting. I was taught that flight is made possible because a (partial) vacuum is created when air flows over a wing and air pushing up under the wing to fill that vacuum creates lift.

Now I am generalizing from that concept. Organisms seek food and the more food available the more pressure there is to fill a vacuum created by the lack of predators.

(Daniel Fisher) #45

Could you explain both of these a bit more?

“From our perspective changes are random…” is there another perspective by which these changes are not random?

“Certain parts of the genome are under selection pressure due to the environment…” I’m not sure exactly what you mean by this, specifically?

(Daniel Fisher) #46

I’m afraid this is a question begging fallacy. If we assume that flight is the result of unguided evolution, then, yes, we can conclude that it must not be all that extraordinary, since it happened those numerous times.

(Lynn Munter) #47

You’re right that we shouldn’t just assume that. A better way to make the point might be to look at how many existing (or extinct) animal forms are somewhere between flight and not-flight, and you might be surprised at the diversity of gliding creatures in the natural world. Squirrels, fish, squid, lemurs, snakes, lizards, ants, and frogs all have species capable of gliding flight. Looking at all these examples, it becomes not so difficult to posit a gradual transition to powered flight, animals which can flap effectively enough to provide lift through the air rather than “just” a more controlled descent.

(Matthew Pevarnik) #48

Here is a great summary of what a ‘random mutation’ means done by @T_aquaticus at Peaceful Science- https://discourse.peacefulscience.org/t/what-random-mutation-means-in-science/3386?u=pevaquark

There are different types of selection pressure that I was thinking of but the basic idea is the genome changes each generation and these changes will (from our perspective) be random. These changes can be neutral, negative or positive.

Negative selection pressure/purifying selection:
Here is an example shared by @sfmatheson a little while back where some researchers found regions of the genome unaffected by mutation which could indicate they are under purifying selection:
Survival bias, WWII planes, and human genetics

Purifying selection can be defined as:
Purifying selection prevents the change of an amino acid residue at a given position in a multiple alignment, thus favoring an excess of synonymous versus nonsynonymous substitutions.

For reference:
Synonymous vs. nonsynonymous mutations which are briefly discussed here-

Positive selection:
Here’s a neat example of looking for parts of the Dolphin genome that are under positive selection pressure that can help learn what makes a dolphin unique:

Note: I probably made at least one error in a nuanced definition so please let me know if that’s the case.

(Mitchell W McKain) #49

That is incorrect. That would ONLY apply IF my statement was an argument was made for the evolution of flight, which it clearly was not anything of the kind. The evidence for evolution including the evolution of flight is amply supplied by other numerous publications. The only claim I made was that in this overwhelming body of evidence we see at least three separate cases where flight evolved. It is NOT the case and you certainly have not established that evolution of flight was assumed in the accumulation of this evidence for the evolution of flight. Rather quite the opposite is the case in which you reject and ignore evidence of evolution based on your preposterous assumption that no such thing occurred.

No the real argument of all scientific inquiry is that it is more reasonable to believe what is consistent with the evidence and what is repeatedly demonstrated by the tests of scientific hypotheses than it is to believe childishly literal interpretations of ancient manuscripts which clearly never had any intention of addressing these scientific questions.

(Mitchell W McKain) #50

A google search quickly brings up photographs of dinosaur feathers trapped in amber. Pretty cool.

Scientists discovered a fragment of a 99-million-year-old dinosaur tail (bones, tissue, feathers and all) preserved in amber. The amber sample had already been polished for jewelry when scientists discovered that it held a bigger treasure: the first dinosaur feathers preserved in amber. Researchers believe the tail came from a juvenile coelurosaur, a sparrow sized dinosaur.

This is from popular mechanics article.

(Roger A. Sawtelle) #51

These transitions have affected most of the cetacean biological systems and allowed them to diversify to different aquatic habitats, dispersing across the world’s oceans, and into estuaries and even rivers [10].

It seems to me that first you say very clearly that no one could possibly answer how dinosaurs could become birds, and then in an article that says how land mammals became dolphins.

The articles says which organs changed to adapt to an aquatic life. We know that based on ecology that natural selection chooses those better adapted to their habitat. Natural selection selected out the dinosaurs except for the avian dinosaurs, but not in the mechanical manner that you say.

Please, read this very carefully. Changes to the genome are Not random. Individual changes are random, because this is how nature initiates change, but changes are selected out if they are negative, that is, if they significantly decrease adaption.

Thus changes in the genome are not random, they are selected in based on adaptation. That is what happened with the birds and the dolphins, and the insects, bats and the flying squirrels. All the evidence is there, so why do you continue to deny the role of ecology in evolution?

(Mervin Bitikofer) #52

Where did Matthew do that?

Are you sure you’re not just making an unwarranted extrapolation from the claim that “x is random”, making it instead to mean: “x is random without any constraint whatsoever”? I know I haven’t followed all your exchanges, so maybe Matthew does say something along those lines (though I very much doubt it). It seems more likely to me that you are insisting that any failure to mention ecology in every sentence is tantamount to denying the role of ecology. But I think the scientist has yet to be produced … from Dawkins to any here … that would actually deny the importance of ecology the way you claim they do. I’m sure Matthew can respond with more nuance, but this is my 30,000 foot impression.

(Roger A. Sawtelle) #53


I was responding to @pevaquark Matthew’s response to @Daniel_Fisher above which begins with the sentence I quoted. This is where he should have talked about natural selection through the environment, but he did not.

I am not sure what his problem is although it could be that he is a physicist who has not made the transition to biological science.


That is only one aspect of natural selection. You like to keep using “ecology” but seem to limit the usage to the environment. In reality it means more than that.

The “competition within and between species” is where the “red in tooth and claw” comes from and it is a part of natural selection just as cooperation is. You have never shown any reason why natural selection should be limited as you seem to indicate.

Again, it is more than just the environment.

(Stephen Matheson) #55

He wrote “From our perspective changes to genomes are random and certain parts of the genome are under very selection pressure due to the environment.” I don’t understand the basis of your claims about what he wrote. It seems that we can insert a negation into each of your sentences to make them accurate.

(Roger A. Sawtelle) #56

Since when? How is the environment different from ecology?

I have not limited natural selection here in any way. It is true that ecologists like Lynn Margulis and James Lovelace and perhaps Edward Wilson have run afoul of Richard Dawkins because they and I understand that ecology is based on symbiosis, living together, while Darwin said that natural selection is based on the opposite understanding of Reality, conflict and survival of the fittest.

Phil @jpm, I watched the video that you posted. To my dismay it portrayed evolution as almost completely the story of genes, or variation. It is the story of ecology or Natural Selection and Variation. This is my problem, because on one side evolutionists say that they have included ecology into evolution, but then they demonstrate that they do not.

@pevaquark Matthew first said that it was impossible to understand how dinosaurs made the transition to birds without waiting for by presentation of what we do understand. Then he said we might know something, but minimized it as if it were insignificant.

The fact is when we assume that evolution is only about genes that we do know very little about this process. When we understand that natural selection and evolution are about changes in the ecology, then we know much more.

Forgive me for being passionate about this issue, but it is difficult for me to see intelligent people refusing to accept facts that enhance our understanding of science and theology for no good reason, just because it seems to contradict what they have been taught. .

(Stephen Matheson) #57

Some of us have corrected this error repeatedly, but for some reason I will try again: the sentence “natural selection and evolution are about changes in the ecology” is false. And this is a shame, because an effort by you or anyone else to maintain a focus on ecology… would be a worthwhile thing. Instead, you suggest that ecology is the main event, and even (strangely) the source of evolution, and that’s incomplete at best. Then you write things like “ecology is based on symbiosis,” and that’s just wrong.

It’s a shame. Ecology is interesting and important, but this conversation is about confusion and non sequiturs, apparently in pursuit of a “theological” understanding of the world.

Ecology, by the way, is not the answer to any interesting question about sexual selection, and that’s just one big reason why your claims about ecology are so flawed. Try this piece for an interesting example:



The environment is only part of ecology.

I provided the definition of ecology above, which you apparently didn’t read, and it does include symbiosis as part of the ecology.

(Roger A. Sawtelle) #59

Ecology is about interactions of organisms and their environment. The environment of an organism includes other organisms, animal and vegetable, which can be food, prey, predator, or bacteria. If you are saying that I limit my understanding of ecology to climate change, that is false.

Now the question as to “red in tooth and claw” I assume you are talking about predation, however predators are not competing with prey for sustenance. Lions are not competing with zebras for grass to eat. It is not in the interest of the lions to eliminate all the zebras. They thin the herds so the sick and weak die and prevent overgrazing. This is the way that nature maximizes the natural resources of the earth for all. [quote=“Bill_II, post:54, topic:40714, full:true”]

That is only one aspect of natural selection. You like to keep using “ecology” but seem to limit the usage to the environment. In reality it means more than that.

The “competition within and between species” is where the “red in tooth and claw” comes from and it is a part of natural selection just as cooperation is. You have never shown any reason why natural selection should be limited as you seem to indicate.

Again, it is more than just the environment.

The question about symbiosis and competition is whether nature can effectively work in two opposing ways at the same time. Gravity does not work one way now and another way tomorrow. Gravity works the same way all the time consistently, and this the way ecology and evolution works, the way I see it. No one has demonstrated to me the contrary.

The article on sexual selection is interesting. It assumes that sexual selection are two separate processes and asks the question, is it possible that sexual selection can harm, rather than strengthen the species.

The usual example here is the peacock whose colorful display opens him to predation, but appears necessary to attract a mate. So we have two contradictory forces here, but since natural selection has selected the peahens and peacocks in because their adaption to their environment out weighs their display, there4 is no serious problem. That is what ecological selection is all about, looking at all of relationships and finding the one that works be4st, even if we do not always understand them.

We can even look the fact that some human females seem to prefer “bad boys,” men who engage in risky behavior and thus seem to be poor choices as mates. Ecology does not say that this is impossible, but raises the question as to why does this happen? so it can be addressed if it needs to be addressed.

As I have said before evolution has two aspects, Variation and Natural Selection. Variation is basically genetic and allows for change. Natural Selection is basically ecological and directs change. Both are needed. I recommend my book Darwin’s Myth. You just might learn something.

Predation is a form an important form of symbiosis. Even zebras eat grass which is a living organism. Humans eat plants and animals, but of course we often kill more than we need and eat more than our share. Ecology teaches us what happens when we violate the rules of nature.


(Stephen Matheson) #60

That’s not what the article was about. I don’t even know what you mean by “it assumes that sexual selection are two different processes.”

What science is about is trying to understand. The view that you describe, of “ecological selection,” is wrong because it doesn’t explain enough. No amount of repetition can change the fact that ecology is not the same as selection and that it is impossible to make sense of evolution without genetics.