What is Evolution?

[Kirran]

@ArtieE @Kirran @Mestemia @gnostic

@Guy Threepwood

@Kirran


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.

Poor old Hardy and Weinberg not being credited!

I really enjoyed this stuff when I was learning about it at uni, it's nice to be reminded of it.

 

[sayak83]

Poor old Hardy and Weinberg not being credited!

I really enjoyed this stuff when I was learning about it at uni, it's nice to be reminded of it.

 

[Kirran]

As a point which will hopefully be easy to read for those evolution sceptics who didn't understand or go through sayak's post, I'd like to point out that in that post was a mathematical proof of evolution. One which can be widely applied to real world populations of organisms.

You may need to read it a couple of times to understand it, and if you still don't I'm sure both sayak and I can try and explain it or direct you to online learning resources.

 

[Acim]

Over the course of many threads here, it has become clear to me that many skeptics of the science of evolution do not understand what evolution is or how it is supposed to work. So I thought it would be good to summarize the main aspects of evolution in a thread so that the basics are clearly expressed for all to see.

Theory of Evolution is a scientific theory (like atomic theory, quantum theory, germ theory) that seeks to explain
1)The origin of the diversity of life on the planet
2)The patterns that exist in this diversity of life
Eg. Why the animals in Australia so different from animals in Eurasia. Why can animals be organized in closely allied groups (cat family, dog family, bear family etc.)
3)Why and how the living creatures have the traits they have and the behave the way they do.
Eg:- Why do some plants have flowers while others are flowerless. Why are whales so different from fish though they both live on water.
4)The specific history of life as uncovered by the fossil record and how patterns in that history makes sense.

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

The theory of evolution seeks to predict:-
1)How species and ecosystems will respond to changes, natural or artificial.
2)To predict and uncover the current evolutionary trajectory of pathogens and how to stay one step ahead in defending against them.
3)Using evolutionary trends and relationships among species in order to be more effective in artificial breeding, GM strains, gene therapy, identification and treatment of genetic disorders etc.

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

Basic features of the theory of evolution
a) Evolution is the change between generations within a population lineage defined by ancestor-descendant relationships. A population is defined by a group of living organisms that inter-breed (or exchange genetic material) often enough over the generations to be considered to have a common pool of genes between them.

This is "what."

b) Genes are specific segments of DNA that determines what proteins get built, how much and when. Proteins build all physical features of the body and controls and constitutes all processes occurring within the organism that determines how it lives and how it behaves.

This is also what, and how.

c) Change within a population of interbreeding individuals is seen when genes are modified or the relative frequencies of various genes are altered.

Also what.

d) The engine for such change are the countless ways strands of the DNA can undergo mutation during the replication process. Typical human mutation rate is 100/generation.

This is how.

e)The mutations cause changes in the genes that in turn cause (in some instances) changes in what proteins are being formed, when and where.

What, when and where.

f)This in turn modifies the structure and behavior of the individuals from one generation to the next and act as a source of variation of characteristics between members of the population and over time.

Also what, a little bit of how.

g) Variation of characters impact (positively or negatively) the ability of the organism to survive and reproduce with others of its population. The organisms that gain an advantage in survival and reproduction leave behind more offsprings that have its genes in the population. Thus genes that improve the survival and reproductive "fitness" of the individual becomes more widespread and eventually dominate over others...until a newer and more "fit" type of gene emerge to outcompete it in turn.

h) This process of enhancement of traits and associated genes that make the organisms better able to thrive in the environment it is in is called natural selection. This is how mutations that confer a survival and reproductive benefit in the organism becomes widespread in the population over time.

i)Over time, a population may change in physical features and behavior so much that it can no longer be called the same species as the earlier ancestral population.

j) If a population gets isolated into two or more groups due to new geographic barriers, the process of mutation and the enhancement of beneficial mutations through natural selection operates independently in both subgroups, making them slowly distinct from each other. Over time, the two populations become so different that they no longer look or behave the same and do not interbreed in the wild. Thus one species splits into two. This process is called speciation and results in the branching tree of life and the present diversity from past forms.

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

Hope the basic theory is clear. I will add more stuff. Let me if you have questions.

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."

 

[Kirran]

Why do you expect the scientific body of facts to give you 'why'? That's not it's purview.

 

[Acim]

Why do you expect the scientific body of facts to give you 'why'? That's not it's purview.

Perhaps you missed it being stated 5 times in the "seeks to explain" part of OP?

But I have come to acutely understand that it is not the purview of science, which is why (yes why) science is outside the domain of (actual) knowledge. Debatable? Sure, but let the debate continue.

 

[Kirran]

Perhaps you missed it being stated 5 times in the "seeks to explain" part of OP?

But I have come to acutely understand that it is not the purview of science, which is why (yes why) science is outside the domain of (actual) knowledge. Debatable? Sure, but let the debate continue.

Yeah, explain the how and what of. Explain how the process works, what we observe, explain why processes occur at the proximal level. At the overall level - why are there stars, why are there atoms, why is there time? Science can't really address that at the deeper level, it has no reason to.

 

[Acim]

Yeah, explain the how and what of. Explain how the process works, what we observe, explain why processes occur at the proximal level. At the overall level - why are there stars, why are there atoms, why is there time? Science can't really address that at the deeper level, it has no reason to.

So, if there is a branch of knowledge / philosophy / understanding that does lay claim to "why these things occur" then perhaps it ought to be along side science. I would say not in the same course, but in the same school, with clear understanding science is addressing what and how, the other course is addressing why. And with understanding (at least among skeptics) that both are a matter of ongoing debate, even while there are (allegedly) some ideas of which we feel fairly confident of at this time/currently. So much so that teachers in the course may reference them as 'facts.'

 

[Kirran]

So, if there is a branch of knowledge / philosophy / understanding that does lay claim to "why these things occur" then perhaps it ought to be along side science. I would say not in the same course, but in the same school, with clear understanding science is addressing what and how, the other course is addressing why. And with understanding (at least among skeptics) that both are a matter of ongoing debate, even while there are (allegedly) some ideas of which we feel fairly confident of at this time/currently. So much so that teachers in the course may reference them as 'facts.'

I guess that would be vaguely in the sphere of religion, spirituality and philosophy. It can be hard to teach formally. I'm not sure that it's advisable.

 

[Acim]

I guess that would be vaguely in the sphere of religion, spirituality and philosophy. It can be hard to teach formally. I'm not sure that it's advisable.

I am sure it is advisable, almost precisely because of science's shortcomings with regards to actual knowledge.

 

[Kirran]

I am sure it is advisable, almost precisely because of science's shortcomings with regards to actual knowledge.

Science is good at dealing with data, explanations and models. It works very well at allowing us to describe natural phenomena and develop technologies based upon this. That is its job.

 

[Acim]

Science is good at dealing with data, explanations and models. It works very well at allowing us to describe natural phenomena and develop technologies based upon this. That is its job.

How well it works or how good it is at dealing with data is opinion, based on own bias. Same thing can be said about the other course, from bias of how well that does with explaining why and/or purpose for certain ideas, intentionally delving deeper than science dares to go.

 

[Guy Threepwood]

As a point which will hopefully be easy to read for those evolution sceptics who didn't understand or go through sayak's post, I'd like to point out that in that post was a mathematical proof of evolution. One which can be widely applied to real world populations of organisms.

You may need to read it a couple of times to understand it, and if you still don't I'm sure both sayak and I can try and explain it or direct you to online learning resources.

Yes, it's a very good mathematical proof of evolution, and very versatile, since it also mathematically proves, when applied to real world populations, that automobiles evolved

proving that either did so through millions of lucky accidents... a little bit trickier

 

[Kirran]

Yes, it's a very good mathematical proof of evolution, and very versatile, since it also mathematically proves, when applied to real world populations, that automobiles evolved

How so?

How well it works or how good it is at dealing with data is opinion, based on own bias. Same thing can be said about the other course, from bias of how well that does with explaining why and/or purpose for certain ideas, intentionally delving deeper than science dares to go.

Practically speaking, it works. It is useful. The results it delivers are useful. That is enough for it to be worth continuing with. Whatever other course you're talking about can be worth continuing with for its own merits.

 

[Guy Threepwood]

How so?


.

again this was just pulling out one random paragraph and changing only names and features:

Certain important features of the surviving autos and the junk yard record that the theory of evolution explains:-

Observed pattern of Progression in the junk yard record:-
Progression is defined as the pattern in the junk yard record in which

i) cars from the earliest strata will look very very different from modern running cars

ii) The cars depicted in the most ancient strata of the junk yard record will be continually replaced by new cars in subsequent strata which, while sharing many features of the earlier cars, will also show modifications in some of the features and emergence of some new features. They in turn will be replaced by new cars in a subsequent strata again showing a similar trend of gradual modifications of features, elimination of some older features and emergence of some new features.

iii) Due to this trend, cars in closely spaces strata will look similar to each other and in more distant strata will look more different. This trend cannot be explained by functional needs due to change in habitat alone as often modified models occupy nearly same kinds of habitats as older replaced species (like Lincolns vs Studebakers, Cadillacs v Desotos etc.)

iv) Levels closer to the present will increasingly show cars that look more and more like modern forms (but not the same).

v) When modern cars are categorized in groups based on character, it is found that the broadest and most generalized of features appear in a primitive form in the earliest cars (like possessing a chassis) while more specific features restricted to specialized subgroups (like having 4WD, having tailgates) appear in cars that appear later in the fossil record. More specialized and restricted the feature, the later it appears (like possessing OnStar as in Chevrolets appears later than possessing 4wd as in SUVs in general).



see? works just as well doesn't it, not sure if that was pointed out to you in 'uni'

 

[Kirran]

again this was just pulling out one random paragraph and changing only names and features:

Certain important features of the surviving autos and the junk yard record that the theory of evolution explains:-

Observed pattern of Progression in the junk yard record:-
Progression is defined as the pattern in the junk yard record in which

i) cars from the earliest strata will look very very different from modern running cars

ii) The cars depicted in the most ancient strata of the junk yard record will be continually replaced by new cars in subsequent strata which, while sharing many features of the earlier cars, will also show modifications in some of the features and emergence of some new features. They in turn will be replaced by new cars in a subsequent strata again showing a similar trend of gradual modifications of features, elimination of some older features and emergence of some new features.

iii) Due to this trend, cars in closely spaces strata will look similar to each other and in more distant strata will look more different. This trend cannot be explained by functional needs due to change in habitat alone as often modified models occupy nearly same kinds of habitats as older replaced species (like Lincolns vs Studebakers, Cadillacs v Desotos etc.)

iv) Levels closer to the present will increasingly show cars that look more and more like modern forms (but not the same).

v) When modern cars are categorized in groups based on character, it is found that the broadest and most generalized of features appear in a primitive form in the earliest cars (like possessing a chassis) while more specific features restricted to specialized subgroups (like having 4WD, having tailgates) appear in cars that appear later in the fossil record. More specialized and restricted the feature, the later it appears (like possessing OnStar as in Chevrolets appears later than possessing 4wd as in SUVs in general).



see? works just as well

You aren't addressing what you quoted. How does this relate to the maths presented by sayak82 in his post describing allele frequencies?

 

[ArtieE]

Yeah, explain the how and what of. Explain how the process works, what we observe, explain why processes occur at the proximal level. At the overall level - why are there stars, why are there atoms, why is there time? Science can't really address that at the deeper level, it has no reason to.

Science can address that. What science can't address is when people claim that some god created stars and atoms and time for some reason or purpose. Science can tell us what an earthquake is and how it occurs and why but it can't tell us the reason and purpose for Poseidon creating it in the first place. Unless they can deduce it from the magnitude and location and other factors.

 

[Guy Threepwood]

You aren't addressing what you quoted. How does this relate to the maths presented by sayak82 in his post describing allele frequencies?

Again we can change the labels and features, the evolutionary algorithm works for life and autos just as well. Some designs exhibit natural selection- favoring a certain change- as found in the design instructions , others remain in stasis with no change for long periods. That can be proven mathematically- in Cars or life? yes

And natural selection of a significant design improvement goes entirely without saying.- not hard to prove, The tricky part is proving how significant design improvements occur by sheer fluke- especially millions of them

 

[Kirran]

Science can address that. What science can't address is when people claim that some god created stars and atoms and time for some reason or purpose. Science can tell us what an earthquake is and how it occurs and why but it can't tell us the reason and purpose for Poseidon creating it in the first place. Unless they can deduce it from the magnitude and location and other factors.

Right. Science can address the mechanical means by which the diversity of life emerged. It cannot address whether any greater will or spirit governs the universe within which this process is observed to occur.

 

[Kirran]

Again we can change the labels and features, the evolutionary algorithm works for life and autos just as well. Some designs exhibit natural selection- favoring a certain change- as found in the design instructions , others remain in stasis with no change for long periods. That can be proven mathematically- in Cars or life? yes

And natural selection of a significant design improvement goes entirely without saying.- not hard to prove, The tricky part is proving how significant design improvements occur by sheer fluke- especially millions of them

You don't seem to know what I'm talking about. Have you read sayak's post #37?