What is Evolution?

[Kirran]

Have you tried it?

Orgies? Or the religion?

Neither, as it happens.

 

[ArtieE]

So we can prove that trial and error works wonders where we have intelligence to select results, provide a motive, goals.

Or if we have natural selection.

 

[Guy Threepwood]

Some atheists have considered this for quite a while.
https://en.wikipedia.org/wiki/Raëlism
So why don't all the theists and atheists join forces and spend all our efforts and resources and money on actually finding this or these Intelligent Designers?

Okay I hadn't heard of them, thanks for the link!

I think kinda we are finding ID, by a process of elimination, It's pretty much down to that or an infinite probability machine... which would create God eventually anyway..

 

[sayak83]

Sure, you said yourself you had difficulty understanding it - but it's really not a terribly difficult concept- it's just written to appear as if it is. let me simplify

some features from individual to individual are different, with no effect on the functionality of the design

other features vary and do have a consequential effect.

we can compare the rates at which each feature is passed on over the other, and so the rate of the selection of the consequential feature over the non consequential one, proving that one is being selected over the other. duh


But again, am I talking about cars or life? I dunno either- because the principle is the same, superior designs will be selected over inferior ones, or ones that are different in an inconsequential way.. we all get that

The problems begin when we realize that random changes with neutral or negative consequences vastly outnumber positives. Acquiring a significant design advantage by design, not a problem, acquiring the same by accident, problematic...

Here is an earlier post showing recent results that suggest that the percentage of beneficial mutations is not small at all.

http://www.religiousforums.com/threads/just-accidental.191045/page-33#post-4945331

Here is also a recent result showing that a beneficial mutation appeared 17 times independently in the lab in different bacterial generations.

http://news.harvard.edu/gazette/story/2013/03/when-timing-is-everything/

What is your justification for claiming
1) Beneficial mutations are very rare?
and
2) Natural selection cannot efficiently eliminate harmful mutations and enhance the frequency of beneficial mutant genes at a rate sufficient enough for evolutionary change?

 

[ArtieE]

Okay I hadn't heard of them, thanks for the link!

I think kinda we are finding ID, by a process of elimination

I thought you had already found ID and are busy concentrating all your efforts on finding the Designer?

 

[Deeje]

You should try reading what's written, and not what you highlight in your mind. These paragraphs answer the questions that you're asking in this response, and they will also answer questions that you'll have in the future. But you're reading them for what you want and not for what they are.

I highlighted what most people read over without noticing the suggestion substituted for fact.

In your following quotes, I'll show you what I mean.

The physical and genetic connection between these ancestral species of whale are factual. The sentences that you fail to highlight because they don't make your point for you tell you as much.

You seem to forget that I do not believe that science "knows" what it is saying. I believe that it says "I think I know" what this bit of bone, or this tooth, or this skeleton is. It makes connections to species who are similar but there is no proof of their relationship that can be backed up by anything but wishful thinking and educated guessing. This is what most people miss in the rhetoric.

Of course these artist renditions are just best guesses - Everyone should know this, if they don't already. The skeletal frames of these creatures have been discovered in their entirety. So the shape is right. The structure of the animal is known. There are only so many ways that mammals can make themselves move. Things like coloration and hair density are little more than educated guesses - but those things don't matter at all. If you stripped all humans of skin color, hair coverage, fat placement, etc, you'd still have a very good idea of how the human body moved and operated, don't you think? Paleontologists do that with ancient bones. There's really no difference.

Again, you miss the point. Paleontologists have a "good idea" of how these beings "moved and operated"....there is just no way to prove a line of decent between them. Finding a fossil in one part of the world and then finding another fossil in a completely different place, supposedly separated by millions of years doesn't prove anything. Science cannot connect them.
Do you see the problem? You cannot establish a chain if there are no links. Science has bits and pieces that they have woven into a chain, but the links are all supplied by imagination......it's a fake chain, connected by nothing more than suggestion.

The important part of the discussions are the facts.

I couldn't agree more! Science has some facts but there is no way to marry them with their theory without the power of suggestion. Couching their rhetoric in scientific terminology and with lots of diagrams demonstrating how they believe it all took place is no substitute for veritable evidence. The fact is no verifiable evidence exists except for adaptation, which is then used as a foundation for fantasy.

These were amphibious creatures, that have only ever been found around the rim of an ancient shallow sea, indicating their reliance on a wet environment. The skeletal features that they share with whales, namely the inner ear bones, are shared with no other organism. Why do you think that is? What little genetic information has been gleaned indicates a clear relation to whales, just as it does to hippos, shrews, squirrels, and all other mammals. (See the first link from Nature that I provided.) The reason for this genetic and physical connection is common descent. If that's not the answer the HOW those things got there, I'd like to know what you think the answer is...

I am not disputing that some animals are aquatic air breathers, which still exist in abundance today.....what I am disputing is the relationship between these creatures in some kind of evolutionary chain, which cannot be proven by any method science possesses.

Dear, these aren't whales... You don't see whales in these pictures, or in these bones, because they're a different creature entirely.

Dear, I am aware that these aren't whales and I am also aware that mammals exist in many forms, both in land and marine creatures to this day. Again, what is missing is the connection. Similarity in the method of feeding the young of any species can just as easily be a design purposely implemented in the vast variety of life. When you begin with a pre-conceived idea, its easy to think that anything else can't possibly be true because it sounds like fantasy....yet you accept an equal fantasy because it comes from a source you have been persuaded to accept.

A picture of your great grandmother doesn't look like you. She no longer exists. But she's a part of you, isn't she? Part of your hair color, or maybe your eyes, or a silly way you smile sometimes came from your great grandmother, but you're two different human specimens entirely. The same is true of modern whales and their ancestors. They look nothing like Pakicetus - but their inner ear structure, the vestigial leg bones in their rear flippers, the cranial structure which allows breathing through a "snout" on top of the head, all point to the Pakicetus as being the first species to delineate and transition into the water.

I like your use of the words "points to" because that says it all really. I can have a compass that "points to" the North, but if there is magnetic interference, it will point me in the wrong direction. Evolution to me, is that kind of interference. Common sense is overridden by unprovable suggestion, which is then taught to the masses as fact.

Again I'll ask you, where do you think these organisms came from, if not from common descent? How can there be clear physical traits shared between species that never breathed the same air? Why do whales have inner ear bones that are only shared with an extinct four-legged species that lived near an ancient shallow sea? Why do those same whales share a large portion of their DNA with Hippos? Why do Manatees? Why aren't Ambulocetus fossils discovered chronologically earlier in the fossil record than Pakicetus?

Because from the perspective of those who believe in an intelligent designer, all species of any living thing have a common source and are all made from the same raw materials. Similarities to us are just expressions of creativity. Diversity is the hallmark of creation.

Can you answer those questions? If you can, do you have anything to support your answers?

Ignoring artists renditions, do you truly see no similarities at all in these two skeletons?

I have answered those questions with no difficulty at all. I need no fancy drawn out explanations and diagrams to prove my point.....it is obvious to me that science sees similarity and immediately jumps to its own conclusions to support its pet theory. If you compare the bone structure in many unrelated living things, you will see similarity because the basic design works. The external appearance may vary, but the similarity in their bones means very little unless you are trying to force "evidence" to fit a theory.

Think of the question that this segment is asking - Was Ambulocetus more aquatic than Pakicetus? Look at the above skeletons again and tell me what conclusions you can draw from the features of Ambulocetus, compared to Pakicetus. There's a connection that we already know of, but you're free to ignore that. Using your personal observation alone, what do you see?

Why are its front legs shorter? Why are its hands/feet enlarged? Why does it have a more muscular tail? Why is the rib cage fatter? What conclusions would you personally make about those observations of an Ambulocetus skeleton?

You are ignoring the obvious......any similarity does not prove relationship. You operate from a premise that is completely flawed, so all the conclusions you reach will be equally flawed. There is nothing linking these species except science's suggestion.

What most people fail to recognize in these introductory passages about most things biological is that they're reading an easier-to-digest, condensed version of the facts. These are not suggestions. The physiological connections between the organisms are known. There is no other explanation for them, given the data that has been (and is being) collected. If you would like to read more detailed (and honestly more bland) data sets, I can let you borrow a few of my journal subscriptions. The science in those is above the head of most people, and the writing style is not at all intended for the general public. But it's the data that matters, not the style.

It wouldn't matter how much data you provided.....it is meaningless unless you can prove what science is postulating.
The fact is NOTHING can be proved, and no connection can be made between these supposed links in this non-existent "chain". The chain is manufactured.....you are blinded by science to the real evidence, which points to a power greater than man who is the source of all life and whose design skills are amazing. Credit where credit is due, I say.

As has been discussed, through genotypical and phenotypical expressions. The geological placement of their remains shows a chronology of their existence. Where those remains have been discovered show their environment. Their physical features and their genetic information show relatedness. General biologic knowledge tells us how offspring are conceived and how sexual organisms reproduce. That same information tells us how gene flow occurs and how environment plays a role in shaping the "preferred" traits in a population. There's all kinds of things, really. And it's all part of a comprehensive understanding of biology indicating common descent, not just of whales but of all currently living things.

To me, all this clearly demonstrates is the existence of a Master Designer. Similarities in creatures now extinct, does not prove "relatedness" in a continuous line of descent. That is an assumption based on interpretation of "evidence"....lets be clear about that. It can equally prove that the Creator was enjoying his creativity before settling on the life forms that would occupy the earth before his creation of man. Dinosaurs were long gone and no creature in existence posed a threat to him in the beginning.

Whilst the Creator test drives his creation, we who are the only beings made in his likeness, are learning valuable lessons about free will and its implementation. We have been given choices about what we will do with this life we have been given, and how seriously we have taken our dominion over all other creation.
The misuse of free will has landed us where we are now. Science has created the ability for evil men to wipe out all life forms this planet....and not just through one means...there are several ways in which all life could be obliterated. Science is to blame for every single one of them.

The pedestal is crumbling and many people are coming to recognize that science is not the champion it makes itself out to be. For all the good they do, there are many more heinous things for which they are responsible.

 

[Skwim]

That's a lie. There are Christian websites that promote Creation and show the science actually proves it rather than contradicts it. Here is one.

www.icr.org

A lie implies that I know there are Christian websites that promote Creation and show the science actually proves it rather than contradicts it, which isn't the case at all. I know of no such website that does. The closest they get to science is using the word "science" in their literature to convince the gullible. The sorry site you link to, the Institute for Creation Research, is no more involved in true science or scientific research than it's involved in publishing cookie recipes. You can get a brief rundown on the organization by clicking HERE

As jonathan180iq said, "It looks like you're new here. You get a pass on this one. " which I agree with. So stick around and present your scientific claims for creationism if you wish. We'll do our best to convince you where they've go awry. OR, just sit back and watch the debates. . . . .hopefully with an open mind.


.

 

[Guy Threepwood]

Here is an earlier post showing recent results that suggest that the percentage of beneficial mutations is not small at all.

http://www.religiousforums.com/threads/just-accidental.191045/page-33#post-4945331

Here is also a recent result showing that a beneficial mutation appeared 17 times independently in the lab in different bacterial generations.

http://news.harvard.edu/gazette/story/2013/03/when-timing-is-everything/

What is your justification for claiming
1) Beneficial mutations are very rare?
and
2) Natural selection cannot efficiently eliminate harmful mutations and enhance the frequency of beneficial mutant genes at a rate sufficient enough for evolutionary change?

good questions


1) significantly beneficial random mutations are very rare:

This is from the article you cited, and it highlights one of the problems

"There could easily be hundreds, or even thousands, of beneficial mutations that can occur in a population of a billion bacteria"

okay, so obviously the guy is trying to be as optimistic as possible here with what he's trying to show in his study, and how significant the 'benefit' is is entirely subjective here-
but let's be generous and say that a thousand significantly beneficial mutations are possible in a population of a billion

that's literally one in a million

So, among a population of less than half a million individuals, the odds are that not one single beneficial mutation will occur in that generation, only deleterious ones, many of them.

So the next generation can still use natural selection to select the best of the crop, but it is the best of, on balance, an inferior generation to the last, not a superior one. Exactly as would be the case with randomly mutating cars-

2)

So now add to this, and it's not a controversial observation, the larger and more stable the population, the more it resists evolution, because even if you supply a superior mutation, it will probably never dominate a population that's 'doin alright' anyway- and he talks about this problem in the article e.g. horseshoe crabs remaining practically unchanged for 100s of millions of years.

Actually- the very first cracks in my prior belief in evolution, came from this very phenomena, I was coding a simulation meant to demonstrate the power of evolutionary algorithms, and was surprised at how difficult it was for apparently blatant advantages to get passed along and dominate the population, even where conditions were made ideal for it, there was always a great chance it would just get diluted and lost before it had the chance to cath on- unless the population was very very small- a handful of individuals. I'm not saying my humble attempt accurately modeled reality by any stretch, just that the algorithm did not play out as effectively I assumed it would

So you need a relatively small, isolated, and stressed population, in order to let the advantage take effect- but this drastically reduces the odds of any advantage arising before the small, stressed population is wiped out entirely, as there is probably a reason it is small and stressed

catch 22, not a slam dunk for ID by any means, just another complication, another puzzle to solve somehow

There's more to it but really must split here, will catch up with you again soon hopefully

 

[sayak83]

good questions


1) significantly beneficial random mutations are very rare:

This is from the article you cited, and it highlights one of the problems

"There could easily be hundreds, or even thousands, of beneficial mutations that can occur in a population of a billion bacteria"

okay, so obviously the guy is trying to be as optimistic as possible here with what he's trying to show in his study, and how significant the 'benefit' is is entirely subjective here-
but let's be generous and say that a thousand significantly beneficial mutations are possible in a population of a billion

that's literally one in a million

I will discuss more later. But you calculations seem wrong on two fronts.
Firstly the rates of mutation in eukaryotes (us) is higher than that of bacteria.
For humans the rate of mutation is 100 mutations per genome per generation
For bacteria the rate of mutation is much less :- 0.001 mutations per genome per generation. (LINK)
The rate of beneficial mutations is 0.00001 mutations per genome per generation (LINK) .
Thus the percentage of total mutations that are beneficial is 1% of all mutations.

This value holds for eukaryotes as well (tests done with amoeba). It is also a fact the eukaryotes like us have a small effective size of the population anyway (than bacteria) and hence the chances of fixation are much higher.

More later....

 

[Deeje]

I don't think drowning the whole planet was fair. If you're going to follow Him bring your own submarine and plenty of supplies. Just in case you and your fellow sheep should do something that pisses him off.

Drowning the planet was the means by which the Creator brought his purpose back on track. It solved a problem that the earth was experiencing at that time when things were interfered with by supernatural beings...it required a supernatural event to displace them. It was also used by Jesus Christ as an example of what will happen again....only this time it will not be a flood.

Just as before....there will be no place to hide.

The "sheep" have no need to worry. They are already on board an 'ark'...it just isn't a floating box this time.

 

[Evangelicalhumanist]

Thanks I will watch for that

The proportion of negative to positive random mutations is one of the problems yes, and it gets to the size of gene pools etc,

there is no easy answer either way- which at the very least is my point. We all grasp this superficially simple, intuitive algorithm- certainly I did in school. random mutation, natural selection, varying environment- what more do you need?, but it gets a little more interesting when you delve in, it at least doesn't work the simple way I thought it did and I think many others do

On being the best method IF...

it gets interesting, and I don't usually get this far with the argument but ..

after using the trial, error, selection method to identify, for instance, the fastest possible combination of accelerating, braking and steering, to get a car around a specific track, . you produce a set of data that represents the best design for this result yes? so with this 'omniscience' on the best design, this trial and error step should not need repeated

But... to reproduce this data, the most efficient way, I found.. rather than re-running the whole trial, error, select process again, or creating a list of resulting control instructions which would be very long and cumbersome,
is to run the trial, error 'evolution' part again, but now using a list of just those particular random changes that were selected - producing a leaner, faster information system, with a form of cryptic compression in effect.

I may not be explaining it very well, but the interesting thing is, that now if anybody were to examine the code, they would see no sign whatsoever of any specific instructions detailing any specific result, they would see only apparently purely 'random' changes, yet producing an inexplicably rapid progression towards success

i.e. they can be truly random mutations, yet pre-selected for a desired pre-determined result at the same time.

Just something to ponder, I don't pretend to be able to solve this mystery, but I do think it's still a mystery, and the information processes, in physics and life, may be key to unraveling it.

You might consider a simple but effective analogy. What if there were a sports league (let's say American Basketball) in which one of the rules was that each season, the winning team got to dispose of one player, and have first pick of any other player in the league to replace him. The first year, this would certainly be an advantage, but that advantage then more easily leads to victory again, and the chance for an even greater advantage. It wouldn't take too many seasons before you had one team that simply could not be beaten.

Well, natural selection works a bit like that. If there is a mutation, if it provides for enhanced fitness for producing offspring, that's like getting first draught choice, and if the mutation is a loser, it is quickly discarded. So the mutation itself is more prevalent in the following generation, and if it continues to provide the same reproductive advantage, it will not be many generations before that mutation essentially "takes over the league," if you see the analogy.

It's a bit like any increasing number series -- Fibonacci numbers, for example, which start simply enough with 0 and 1 and then says each term following is the sum of the 2 previous terms. Thus: 0 , 1 , 1, 2, 3, 5, 8, 13, 21, 34....see?

 

[Evangelicalhumanist]

We have to specify the fitness functions to get exactly what we want. Again the trial and error antenna is the most efficient antenna, nothing more. The vast array of living thing, resulting ultimately in sentience, a consciousness that can actually experience creation from within- if we knew how to specify for that, perhaps we could create consciousness ourselves, but it's clearly not an easy task.

I've read this sort of thing in a couple of your posts now -- this tendency you have to get "choice" into the mix. "We have to specify the fitness functions to get what we want." Nature is not "getting what it wants," because it doesn't want anything. There is only one "fitness function," and it is as simple as it can possibly be: does whatever (slight) modification provide a reproductive advantage or disadvantage (that is, will the modification result in more copies of itself, or fewer, in succeeding generations)? From there, everything works perfectly!

Consider: about 66 million years ago, the asteroid that was so unfriendly to the dinosaurs may well also have caused a very abrupt (by geological standards) raising of the Himalayas. Think what might happen to the offspring of a single species whose members were divided by that uprising -- some on the windward side, some on the leeward. The offspring of the same creature are just about certain to evolve in different directions in their now-distinct and mutually unreachable environments.

That is really the only "choosing" that is going on.

 

[Acim]

Do we provide funding so he can begin looking for this god or gods and provide evidence for their existence?

Who is we here? And why are we providing funding? And what, if anything, does this have to do with the thread? Seems to me to be another discussion. Admittedly, tangentially related but I dunno, why not fund philosophers while we're concerned about funding scientists? How about if you don't want to fund either, that's an option?

 

[Evangelicalhumanist]

Being a skeptic, I'll just note that the explanation doesn't (really) explain why. Perhaps how and what.

Why = for what reason or purpose
How = in what way or manner
What = asking for information specifying something



See, no "why" here, nor is it necessary for prediction.




This is "what."



This is also what, and how.



Also what.



This is how.



What, when and where.



Also what, a little bit of how.



Again, how, what and a little bit of when and where.



In all of these instance why is still not explained, and very much could be asked. To which I, a skeptic, would not be surprised if the why is conceded as not really something evolution seeks to explain.

In my non-skeptic opinion (or understanding) there is an undercurrent of why, but I'm thinking few wish to frame it this way given the implication, that we as aspect of nature are (obviously, self evidently) evidence of intelligent designers within the natural course of life. Everything about this speaks loudly of intelligence and finding the design/patterns that are determined by intelligent correlations. Yet, I very much understand why we may show up skeptical in relation to this implication, and rather stick to the safety zone of "how" and "what."

This "why" question always gives me pause, when referring to natural things. It presupposes that there is some choosing going on, that there is a purpose (which implies a "purpose") to everything. (Heck, even the Bible says that -- "to every thing there is a purpose.") But what if there's not? what if there's nobody/nothing picking? Then "why" is really an invalid question.

I once thought about this with regard to myself -- "why was I born?" You cannot really answer such a question, because it is essentially meaningless. I was born because my mother carried me term. She carried me to term only because my father's sperm got lucky with her ovum. That only happened (and they were teens, by the way), because there was an opportunity that was taken for a little private hanky-panky. But that opportunity only arose because they were both around, so we now have to go back to why they were born....it's never-ending.

As every frustrated parent in history has discovered, there comes a time when the child asking "why" must be stopped with "just because!"

 

[Milton Platt]

Nice post.

However, the problem with almost all creationists, including those here on RF isn't that they don't understand what evolution is or how it is supposed to work, but that they don't care to. Having committed themselves to the utter truth of the Bible, anything, no matter what it may be, ethics, the variety of life, or the formation of the universe, has to completely agree with their beliefs or it's simply false. No ifs, ands, or buts. Oh, they'll pick up on a point or two to debate, but it isn't to attain a better understanding. It's to refute and try to demolish the beast of evolution that threatens the peace of mind their religion brings them. The thinking being: if evolution is right then my religious theology has to be wrong, And if that's wrong, what is there to live for . . . . well, perhaps not bad, but they've got a huge emotional investment in the truth of their faith. One that's just too valuable to allow to be picked at. Hell, just look at any of the creationists web sites and see how much they're forced to lie about evolution. Why lie? Because on its own creationism has virtually nothing to stand on other than "The Bible tells me so," whereas evolution is backed by impartial evidence, reason, and logic, things religious faith can't lay claim to . . . . . . . well, justifiably anyway.

Again, good post.


.

You're only saying that because it's true.......

 

[Milton Platt]

By that definition Genesis describes evolution also. But why it changed as it did is teh question right?, why it created sentient beings able to ponder and appreciate their world, deduce a creator for it, give thanks.. coincidence?

What are the evolutionary steps described in Genesis? What are the evolutionary mechanisms outlined in Genesis? There does not have to be a why. there only has to be a how.

 

[Milton Platt]

Orgies? Or the religion?

Neither, as it happens.

If you have tried the former, please provide a detailed description. If you have tried the latter, don't bother.

 

[Acim]

This "why" question always gives me pause, when referring to natural things. It presupposes that there is some choosing going on, that there is a purpose (which implies a "purpose") to everything. (Heck, even the Bible says that -- "to every thing there is a purpose.") But what if there's not? what if there's nobody/nothing picking? Then "why" is really an invalid question.

That would be correct. But same philosophical games can be played with the what of the equation, such that "what if physical existence is unreal?" Then how and what we describe it as is invalid. Yet, some people (clearly a majority) either believe or (in my case) know there is a purpose. While others, philosopher/skeptic types see it as matter of ongoing debate, worthy of discussion that is not in the domain of science.

I once thought about this with regard to myself -- "why was I born?" You cannot really answer such a question, because it is essentially meaningless. I was born because my mother carried me term. She carried me to term only because my father's sperm got lucky with her ovum. That only happened (and they were teens, by the way), because there was an opportunity that was taken for a little private hanky-panky. But that opportunity only arose because they were both around, so we now have to go back to why they were born....it's never-ending.

Interesting how you went from "meaningless" to "never-ending" all on your own. Guess what, I see the need to describe and predict the physical as both meaningless and (relatively) never-ending.

As every frustrated parent in history has discovered, there comes a time when the child asking "why" must be stopped with "just because!"

As every Gnostic knows, there comes a time when a child claiming they understand the physical, needs to be told, yeah, you've only scratched the surface of actual knowledge/understanding.

 

[sayak83]

Quantifying the absence of Natural Selection.

A common criticism from some creationists here is that evolution through natural selection is a just-so story without there being any way to detect whether it is happening or not. This is not the case. There are many objective and mathematical ways to detect whether a specific gene or a group of genes is under natural selection or not.

I will present a simple example to show this. Consider a gene that has two variants (alleles) a and b. Then a population of creatures can have the variants aa, ab or bb. If N be the total number of creatures in the entire population and N(aa), N(bb) and N(ab) are numbers possessing the various variants then :-

Fraction of the population with gene-type aa is f(aa) = N(aa)/N
Fraction of the population with gene-type ab is f(ab) = N(ab)/N
Fraction of the population with gene-type bb is f(bb) = N(bb)/N

One can evaluate this by statistical sampling in an animal population for example.

Since all creatures have a pair of chromosomes, there are two positions for every gene, one from the father and one from the mother. So, gene a occupies both positions in individual of type aa; occupies one position in individuals of type ab; and is absent in individuals of type bb.

Thus frequency of occurrence of gene variant a of the gene in the population is
g(a) = [2N(aa)+N(ab)] /2N = f(aa) + 0.5f(ab)

Similarly frequency of occurrence of gene variant b of the gene
g(b) = [2N(bb)+N(ab)]/2N = f(bb) + 0.5f(ab)

So far so good. But now of we assume that selection is absent. Thus:-
i) Mating preference is unrelated to the gene variants . That means no sexual selection effect exists on the genes and mate choice is random with respect to this gene variants a and b
ii) All variants (aa, ab, bb) have the same fertility potential and produce on average the same number of babies.
iii) These gene variants have no effect on the rate of survival of the babies into adulthood. Thus Natural Selection is not operating on these gene variants.

Then it can be mathematically proved that:-
1) Gene frequencies and populations fractions are constant from generation to generation.
2) They obey the equilibrium relation:-
f(aa) = g(a)*g(a)
f(ab) = 2g(a)*g(b)
f(bb) = g(b)*g(b)

These will be the population fractions and gene frequency relations if natural selection is not operating on a gene. While most genes show selection effects, there are some whose variants are neutral and they (like the blood group type MN variants) do show this equilibrium relation in the populace.

These relations can be extended to genes that have three or more variants as well.

Conclusion:-
1) It is not the case that we have no clue as to determine when natural selection is operating and when it is not. The distribution of gene variants in case of general absence of selection (no sexual selection and equal fertility, equal survivability to adulthood) can be determined mathematically and genes have been identified that satisfy these neutral under evolution criteria.

2) But many genes do not follow the equilibrium relations and how much and the manner of the deviation tells the scientists which process of evolution is acting on the gene.

@ArtieE @Kirran @Mestemia @gnostic
@Guy Threepwood
@Kirran
@Evangelicalhumanist

Can Natural Selection make a Rare but beneficial gene variant dominate over time?

The short answer is yes, and in quite a short while.

Last time I looked at the condition where natural selection is not operating at all. Thus:-
1) The gene variants (say a and b) have no effect on who chooses whom to mate
2) The gene variants (say a and b) have no effect on fertility of mating
3) The gene variants (say a and b) have no effect on survivability to adulthood

Now let me consider natural selection by removing (3). So the gene variants a and b does have an impact on how many babies survive into adulthood. Maybe the mutant gene a confers disease resistance (to plague or malaria) or makes the baby more able to digest cow-milk or create a more camouflaged coat that helps the baby (say baby deer) to avoid the gaze of lions.

Suppose babies with genotype aa and ab both have the desirable feature that helps them survive.
Suppose that for every 100 babies with normal genotype bb that are born, only 45 survive to adulthood and mate.
But for every 100 babies born with genotype aa or ab, having the beneficial mutant gene, 50 survive to adulthood and mate.

So for every individual with aa or ab that survives, the number of individuals with bb that survive are:-
45/50 = 0.9 This is called the relative fitness (or just fitness) of the genotype bb with respect to the most fit genotype aa or ab.

Since fitness is measured relative to the survival rate of the most fit genotype we have

Fitness of aa and ab= 1.0
Fitness of bb = 0.9

Symbolically we write
Fitness of aa = 1
Fitness of ab = 1
Fitness of bb = (1-s) where s is called the selection coefficient where in this example s=0.1

As before, let

Fraction of the population with gene-type aa is f(aa) = N(aa)/N
Fraction of the population with gene-type ab is f(ab) = N(ab)/N
Fraction of the population with gene-type bb is f(bb) = N(bb)/N

And again the frequency of occurence of each gene variant in the population will be

Gene frequency for gene type a
g(a) = [2N(aa)+N(ab)] /2N = f(aa) + 0.5f(ab)

Similarly frequency of occurrence of gene variant b in the population
g(b) = [2N(bb)+N(ab)]/2N = f(bb) + 0.5f(ab)

But now, due to selection, the frequencies change from one generation to the next. One can mathematically show that:-

The increase in gene frequency of gene a from one generation to the next is
g(a)_nextgen - g(a) = s*g(a)*g(b)*g(b)/[1-s*g(b)*g(b)]
and

The decrease in gene frequency of gene b from one generation to the next is
g(b)_nextgen - g(b) = -s*g(a)*g(b)*g(b)/[1-s*g(b)*g(b)]



Then the genotype frequencies of the variants aa, ab, and bb in the next generation is

aa : ab : bb = g(a)*g(a) : 2g(a)*g(b) : g(b)*g(b)*(1-s)


Note that not only are the gene frequencies changing each generation, their relative ratio is also now different from the equilibrium values. Hence both the fact that selection is happening and magnitude of the selection can be determined by simply calculating the relative distribution of the variant genotypes in the population.


Consider an example where

Fitness of aa is 1
Fitness of ab is 1
Fitness of bb is (1-s) where s=0.01. So fitness of bb is 0.99.
This means that for every 100 individual of aa or ab that survuive to adulthood, 99 individuals of bb also survive. That is not a lot of difference, you would agree.

Assume that the new beneficial mutation a is quite rare. So its gene frequency at the start is g(a)=0.01


Using the mathematics above one can easily construct a generation to generation gene frequency table.
Here goes


Generation:-_ 0------ 100----- 200----- 400----- 600------ 800----- 1000
g(a):- ______ 0.01---- 0.026----- 0.07------ 0.28----- 0.55----- 0.72----- 0.8
g(b):-_______ 0.99---- 0.974----- 0.93----- 0.72----- 0.45----- 0.28----- 0.2

Also the relative fractions in the population carrying each genotype is


Generation.............................aa:ab:bb

0-------------------------- ----------0.0001:0.02:0.97

100 ----------------------- ------- 0.0007:0.051:0.94

200 -------------------------------0.0049:0.13:0.86

400-------------------------------- 0.08:0.403:0.513

600-------------------------------- 0.302:0.495:0.2

800-------------------------------- 0.513:0.403:0.08

1000 ------------------------------- 0.64: 0.32:0.0396



Thus 1000 generations is sufficient to achieve domination by a mutant gene that is just a little advantageous (100 survive instead of 99) in those who have it. For small mammals, fishes etc. one generation is less than a year, and so the entire process can happen in a 1000 years. Even for longer lived humans with generation time of 30 years, the process takes 30,000 years or less.

This shows that natural selection is efficient enough to fix good mutations in the population quite quickly.

It has been experimentally shown that the rapid development of pesticide resistence in insects (mosquitoes, flies, caterpillars etc.) is due to such rapid pace of fixation of poison resistant variants in the insect population due to selection pressures (s) of pesticide use.

This is a simple theory and realistic models are often a bit more complicated. But it shows somethings. It shows that words like fitness, survival rate and selection are vanilla scientific terms with mathematical expressions and functions. No grand conspiracy or ideological rhetorical flourishes here. Just simple math that happen to model aspects of biological reality well and hence prove useful to science. That's the take home message.

 

[Evangelicalhumanist]

The best answers in this thread are simply too long! I've observed the anti-evolutionists for a long time now, and I can state with great confidence

• They will not study the actual evidence, nor even go to the bother of reading a "science for the layman" book on the subject
• They will not give any evidence for what their Designer was trying to accomplish, nor why
• They will not read you long posts, nor survey the evidence

What they do is demand that you take over 150 years of study, museums and universities stuffed with evidence, hundreds of thousands of carefully crafted papers, the work of tens of thousands of scientists, millions upon millions of words and diagrams -- and condense all of that into a tweet, just a few words, that "prove" what they refuse to listen to.

What they will do is demand that you turn a cat into a dog, before their eyes.

It's stupid, it's lazy and it's pig-headed. But unless you can do those things, you'll never reach them.

I say, leave 'em. If ignorance is bliss, well who am I to take their bliss away from them?