Evolutionary Fitness and Natural Selection

Techne

Honorary Master
Joined
Sep 28, 2008
Messages
11,155
I am interested to hear from the scientists on this forum (non-scientists are of course also welcome to share their opinions) about their understanding of these concepts.

Evolutionary fitness, as far as I understand, appear to play a central role in understanding the concept of natural selection. There appear to be at least two different views about evolutionary fitness:
1) The propensity view of fitness.
2) The statistical view of fitness.

The propensity view, in a nutshell, views fitness is a probabilistic propensity/potentiality and it is a causal factor.

The statistical view, again, in a nutshell, views fitness as a statistical probability and (as Alex Rosenberg argues) "deprives fitness of any causal or explanatory power".

The debate between these views are interesting and ongoing. Here are a few articles:
Two ways of thinking about natural selection
Selection and Causation (argues against a causal view)
Fitness and Propensity’s Annulment?
Fitness (Stanford Encyclopaedia)
Matthen and Ariew’s Obituary for Fitness: Reports of its Death have been Greatly Exaggerated (argues for a causal propensity view)
What fitness can't be (argues against a causal view)

I think it is fair to say that an understanding of the process of natural selection requires a clear understanding of what evolutionary fitness is. Or as John O. Reiss notes:

The rigor of this approach, however, is lessened because there is as yet no universally agreed upon measure of fitness; fitness is either defined metaphorically, or defined only relative to the particular model or system used. It is fair to say that due to this lack, there is still no real agreement on what exactly the process of natural selection is. This is clearly a problem.
How do you understand the concept of evolutionary fitness?

And what about the concept of natural selection? How would you answer the following questions (elaborated over here).
1) Is natural selection a prescriptive or descriptive term?
2) Is natural selection a mechanism?
3) Is natural selection a cause or a force?
4) Is natural selection a process or an outcome?
 

Swa

Honorary Master
Joined
May 4, 2012
Messages
20,841
1) descriptive
2) yes
3) neither
4) process

Popper's wife described natural selection as something that doesn't result in fitness but eliminates the unfit.
 
Joined
Mar 7, 2013
Messages
230
snip

How do you understand the concept of evolutionary fitness?

And what about the concept of natural selection? How would you answer the following questions (elaborated over here).
1) Is natural selection a prescriptive or descriptive term?
2) Is natural selection a mechanism?
3) Is natural selection a cause or a force?
4) Is natural selection a process or an outcome?
They don't know the answers.

Evolutionary theory is a "theory" based on "facts" that have not fully been proven as yet.

Evolutionary theory has much evolving to do me thinks, thats just my opinion though.
 

Ponderer

Expert Member
Joined
Jan 8, 2019
Messages
1,745
1) descriptive
2) yes
3) neither
4) process

Popper's wife described natural selection as something that doesn't result in fitness but eliminates the unfit.
Hi.
Can it perhaps be argued that natural selection can be seen as a mechanism/process that removes denatured/unfit DNA?
 

Swa

Honorary Master
Joined
May 4, 2012
Messages
20,841
Hi.
Can it perhaps be argued that natural selection can be seen as a mechanism/process that removes denatured/unfit DNA?
Who or what does the selecting though? Without an intelligent process "fit" DNA would be removed as well. We see that with genomes containing more and more mutations.
 

Jonny_9

Active Member
Joined
Oct 19, 2017
Messages
75
Who or what does the selecting though? Without an intelligent process "fit" DNA would be removed as well. We see that with genomes containing more and more mutations.
I would say that fit and unfit DNA are both removed and kept. The flow is dynamic. Some wins. Some losses. And often the balance is a bit in favour of the wins that are only an advantage for the particular environment of the species. Colder climate, slightly thicker coat or fat layer as a basic example.
I don't believe there is any end-game or mystical hand guiding it. It just flow with wins and losses.
And it is probably the most beautiful and fascinating natural tale of this planet.
 

Ponderer

Expert Member
Joined
Jan 8, 2019
Messages
1,745
Natural selection is used in different contexts.

On a cellular level (at conception).
I doubt that anyone would disagree that natural selection is nothing other than a "chemical reaction" - where there is a straight-forward 1 out of 2 probability that a particular chunk of genetic material will be inherited from either the male or the female.

On a macroscopic level.
In this context, it can surely be argued that selection is associated with consciousness (decision making).
The selection process might be subliminal (instinctive), but is nevertheless a process that is associated with consciousness.

The above is purely a personal view/opinion, and I would appreciate any critique.
 

LD50

Senior Member
Joined
Mar 25, 2019
Messages
675
It's a damn shame that the polar bear wont benefit from natural selection. It got him there, but now **** is reversing to bring about its extinction
 

Ponderer

Expert Member
Joined
Jan 8, 2019
Messages
1,745
I don't see any connection between natural selection and extinction - extinction might be natural, but there is no selection process.
 

Jonny_9

Active Member
Joined
Oct 19, 2017
Messages
75
I am not sure if you gentlemen grasp how slow natural selection is.
We are talking millions of years for a subtle change that may or may not be beneficial. A polar bear and ice cap melting is, in the timeline of natural history and evolution, a blip in time that likely won't be noticed on a long-term graph. But will nonetheless be a disaster for the polar bear and the other creatures that are part of the bear's ecosystem.
 

Bobbin

Executive Member
Joined
Oct 22, 2009
Messages
6,301
I don't see any connection between natural selection and extinction - extinction might be natural, but there is no selection process.
If two species exist and one goes extinct due to the environment, nature has selected the survivor. Sure, it isn't conscious selection but it is selection nonetheless. The word "selection" has a different meaning in a biological context...

1555244009302.png
Think of it as "natural outcome" if you don't like the word "selection". But I believe it also entails the selection of mating partners and so on.

1555244374626.png

This is why blind cumulative processes probably work in this context, because the working/successful entities simply survive.
 
Last edited:

Swa

Honorary Master
Joined
May 4, 2012
Messages
20,841
If two species exist and one goes extinct due to the environment, nature has selected the survivor. Sure, it isn't conscious selection but it is selection nonetheless. The word "selection" has a different meaning in a biological context...

View attachment 645736
Think of it as "natural outcome" if you don't like the word "selection". But I believe it also entails the selection of mating partners and so on.

View attachment 645738

This is why blind cumulative processes probably work in this context, because the working/successful entities simply survive.
I don't think there is any drive towards success. What makes a green snake better at survival? There is only culling of bad traits/mutations but most still survive.
 

Ponderer

Expert Member
Joined
Jan 8, 2019
Messages
1,745
If two species exist and one goes extinct due to the environment, nature has selected the survivor. Sure, it isn't conscious selection but it is selection nonetheless. The word "selection" has a different meaning in a biological context...

View attachment 645736
Think of it as "natural outcome" if you don't like the word "selection". But I believe it also entails the selection of mating partners and so on.

View attachment 645738

This is why blind cumulative processes probably work in this context, because the working/successful entities simply survive.
The part of your response.
"If two species exist and one goes extinct due to the environment, nature has selected the survivor. Sure, it isn't conscious selection but it is selection nonetheless."
Your anthropomorphism of "nature".
Extinction is simply extinction - there is no selection process - there is no "selection" that is performed by "nature".
 

ToxicBunny

Honorary Master
Joined
Apr 8, 2006
Messages
81,234
"If two species exist and one goes extinct due to the environment, nature has selected the survivor. Sure, it isn't conscious selection but it is selection nonetheless."
Your anthropomorphism of "nature".
Extinction is simply extinction - there is no selection process - there is no "selection" that is performed by "nature".
So very very cute.... you've moved to a new thread to peddle your lies and display your lack of knowledge.
 

Ponderer

Expert Member
Joined
Jan 8, 2019
Messages
1,745
I don't think there is any drive towards success. What makes a green snake better at survival? There is only culling of bad traits/mutations but most still survive.
Can it therefore be argued that natural selection can be seen as a process that removes denatured/mutated DNA?
 

Nerfherder

Honorary Master
Joined
Apr 21, 2008
Messages
24,459
Hi.
Can it perhaps be argued that natural selection can be seen as a mechanism/process that removes denatured/unfit DNA?
No.

The main reason is that there is no basis for defining "unfit DNA". A genetic variance/change is just that, it will either hinder or help an organism in their environment.

A genetic change that hinders an organism in one environment might help it in another environment. So its never defective - it might just not suit any available environment.

Its easiest to think of it like this. Fish were coming on to land long before they had the ability to breathe air (like we do). At some point they evolved this ability, it was a defect that made them unable to breathe under water but an enhancement that let them breathe on land. Its probably one of the biggest evolutionary jumps but was still a defect.

Then also consider blind fish that have evolved in caves. Seeing is definitely an advantage but losing that ability did not hinder the species at all. They thrived with this new defect.
 

Ponderer

Expert Member
Joined
Jan 8, 2019
Messages
1,745
No.

The main reason is that there is no basis for defining "unfit DNA". A genetic variance/change is just that, it will either hinder or help an organism in their environment.

A genetic change that hinders an organism in one environment might help it in another environment. So its never defective - it might just not suit any available environment.

Its easiest to think of it like this. Fish were coming on to land long before they had the ability to breathe air (like we do). At some point they evolved this ability, it was a defect that made them unable to breathe under water but an enhancement that let them breathe on land. Its probably one of the biggest evolutionary jumps but was still a defect.

Then also consider blind fish that have evolved in caves. Seeing is definitely an advantage but losing that ability did not hinder the species at all. They thrived with this new defect.
Your argument is entirely teleological.
What makes you believe that fish "came on to land long before they had the ability to breathe air".
 

Nerfherder

Honorary Master
Joined
Apr 21, 2008
Messages
24,459
Your argument is entirely teleological.
You are very confused and have completely misunderstood my post - perhaps even quoted my post instead of another.

Its the furthermost thing from teleology.
What makes you believe that fish "came on to land long before they had the ability to breathe air".
Science B!tch !

Fossils mostly, also fish species that currently do this. Many of these evolutionary stages still exist today... like the Barbel.
 
Top