Chance and evolution

[Biochemist]

Do you not understand the meaning of the word EXACTLY?

I do. And I answered your question expliticly.

 

TM, if you would like to participate in this discusion, please offer questions that do not appear perjoritive.

[Biochemist]

...Roll all six dice at once. If you get any dice that are 1's, put them off to the side and pick up the remaining dice and roll them. Continue this process until there are no more dice to roll.

 

It is clear that you wouldn't to spend your time on Method #1 (assuming 1 roll per second, on average Method #1 would take ~13 hours and Method #2 would take ~1 min). Because of natural selection and its system of attribute preservation and loss, evolution builds on its successes and cuts its failures. Everything is a process taking place on huge timescales....

Sk-

 

I do understand this argument. But the source of the "selection" mechanism is difficult to establish when a new biochemical system had no chance for selection. The narrow case of the discussion has been discussed in great length in the current thread on "punctuated equilibria theories", where it appears that there are many instances where there was (apparently) little or no opportunity for the species to express a dramatic new phenotype (typically called a "body plan") for selection. New body plans are likely to have one or more new enzyme systems that appear to express themselves suddenly de novo. This is the gist of the argument for punctuated equilibrium in the fossil record.

 

The math model I cited above describes a relatively simple example of such a case. We have hundreds of examples of complex biochemical systems where the precursor proteins do not appear to preexist in a parent species before phenotypical expression in the daughter species. Yet the expression does indeed occur. That is, we seem to get reasonably complex systems with no opportunity for selection based on differential performance of the phenotype.

 

I am suggesting that in these circumstances, 1) natural selection is irrelevant, and 2) the mathematical incongruity is unaddressed by the broadly held theories.

[skuinders]

My post was not really directed towards your arguments in particular. I am not educated enough in the biological sciences to debate you on this topic... my point was a general one that deals with a common statement mostly made by lay people. Even if natural selection was not even part of biological evolution as we know it, it is still a valid computational model and that is enough to dismiss the argument (since they are really arguing against the plausibility of the proposed process).

[TeleMad]

TeleMad: [Most of the definingn mammalian characteristics - mammary glands, hair, placenta (for most mammals), endothermy - wouldn't be easily preserved in the fossil records for the very first mammals]. In other words, EXACTLY what are you looking for when you are looking for "pre-mammals" in the fossil record?

 

Biochemist: Morpohological similarity.

 

TeleMad: Do you not understand the meaning of the word EXACTLY?

 

Biochemist: I do. And I answered your question expliticly.

 

No you didn't. Do you REALLY not know what the word EXACTLY means? Do you really belive it means "be as vague as possible"?!?!?!?!

 

But I guess you intend to continue to dodge the question. Oh well, if you can't clearly state what you are talking about, I guess you must not know enough about the topic to be specific.

 

Now, are you suggesting that the fossil record indicates that mammals just poofed into existence all at once out of nowhere, without any predecessors? If so, have you forgotten about the skeletal evidence that shows mammals evolved from reptiles? For example, there is a transitional skeletal series leading from the jaw bones of reptiles to the ossicles (middle-ear bones) of mammals. So mammals are linked back to their reptilian predecessors: they didn't magically appear out of thin air.

 

And bad news for you ...

 

"The evolutionary descent of mammals from their earliest amniote ancestors is perhaps the most fully documented transition in vertebrate history." (Integrated Principles of Zoology: Tenth Edition, Hickman, Roberts, & Larson, McGraw Hill, 1997, p597)

[TeleMad]

My post was not really directed towards your arguments in particular. I am not educated enough in the biological sciences to debate you on this topic... my point was a general one that deals with a common statement mostly made by lay people.

 

Your distinction between the two probablitistic methods of obtaining a given outcome is valid to biology and evolution. It is useful in refuting the assertions made by Creationists related to a tornado running through a junkyard and forming a 747. The Creationists claim that there's nothing but chance operating and the final product needs to be formed all at once. Of course IF that were true, then their method of rolling dice would be correct. But they're wrong: evolution uses both chance AND selection, AND the final product is the end result of a long sequence of mutations/selelection incrementally building up to the final product. That follows your method of rolling the dice.

[Biochemist]

...it is still a valid computational model and that is enough to dismiss the argument...

I do take your point, SK. But I do often think that it is unfounded (for basic science folks) to automatically default to natural selection based on mutation. Based on even a cursory review of the probabilities, there are a lot of issues.

 

There is a tendency among the science sorts to be a little reactionary. Well, actually that would be a tendency among humans. Nevertheless, I often see your argument about directed probability used in contexts where there are legitimate, practical questions about mutation-based selection. There are only about 10^14 generations of life possible since the first prokaryote (assuming 20 minute generations for 4 billion years) It is realtively simple to build system models where the liklihood of random viability of a set of enzyme systems is lower than 1 in 10^1000. That is not a typo. In many cases, the best empirical evidence does not usually get the probability up to any better than one in a billion. It often takes some soft assumptions to bridge that gap, and there are an awuful lot of cases where the gap cannot be credibly bridged.

 

When folks respond with the sequential-dice argument, I usually think that they are offering a knee jerk reaction. (I don't mean to accuse you in this case.) But there remain a number of biological systems for which it is extremely difficult to posit a series of mutations guided by natural selection.

 

The other side of the coin is that folks assume one is offering a theistic solution if you critique the fundamental assumptions of speciation via mutation. But the propensity to dislike a hypothesis because of the implications of the conclusion is not science. It is bias.

[Biochemist]

...are you suggesting that the fossil record indicates that mammals just poofed into existence all at once out of nowhere, without any predecessors? ...

I am suggesting that the body of evidence that supports Punctiated Equilibrium is a valid position. The thesis is that most major body plans (Phyla, Classes, Orders) showed up quickly without any obvious morphological presursor.

 

If you thinke the PE position is bunk, just say so, and I will quit referencing it. There is no need to be hostile.

[TeleMad]

I am suggesting that the body of evidence that supports Punctiated Equilibrium is a valid position. The thesis is that most major body plans (Phyla, Classes, Orders) showed up quickly without any obvious morphological presursor.

 

Perhaps you should read this page

http://daphne.palomar.edu/ccarpenter/reptile%20to%20mammals.htm

which starts off with

 

We also have an exquisitely complete series of fossils for the reptile-mammal intermediates, ranging from the pelycosauria, therapsida, cynodonta, up to primitive mammalia (Carroll 1988, pp. 392-396; Futuyma 1998, pp. 146-151; Gould 1990; Kardong 2002, pp. 255-275).

 

and the page it links to at the top

http://www.talkorigins.org/faqs/faq-transitional/part1b.html#syn2mamm

which starts with

Transition from synapsid reptiles to mammals

This is the best-documented transition between vertebrate classes.

 

That should give you some good info to mull over.

 

Biochemist: If you thinke the PE position is bunk, just say so, and I will quit referencing it. There is no need to be hostile.

 

I don't think PE is bunk, just the special-creation arguments that some people try to mold out of the theory.

 

And PE and gradualism are not mutually exclusive or contradictory, despite what many Creationists would have us believe: PE is quite compatible with gradualism. While skeletons - which are what fossilize the most readily - are remaining relatively static for long periods in some lineages, much biochemical and other non-skeletal evolution - which doesn't fossilize - can be ongoing.

[TeleMad]

TeleMad: I don't think PE is bunk, just the special-creation arguments that some people try to mold out of the theory.

 

And PE and gradualism are not mutually exclusive or contradictory, despite what many Creationists would have us believe: PE is quite compatible with gradualism. While skeletons - which are what fossilize the most readily - are remaining relatively static for long periods in some lineages, much biochemical and other non-skeletal evolution - which doesn't fossilize - can be ongoing.

 

Another way in which PE and gradualsim are not mutually exclusive. Consider Darwin's finches. Their beak sizes fluctuated in size depending upon environmental conditions: during drought years the smaller and feebler beaks were less fit and the larger beaked birds outreproduced them; then when the drought was over, the small phenotype was no longer as strongly selected against and increased in frequency. Yet how many of those transitions were fossilized? Probably none. If someone a million years from now found fossilized remains of Darwin's finches, they'd have no idea from the fossils themselves that these gradual evolutionary changes continually occurred.

[DAK]

<during drought years the smaller and feebler beaks were less fit and the larger beaked birds outreproduced them; then when the drought was over, the small phenotype was no longer as strongly selected against and increased in frequency.>

 

Wonder what the math is on the possibility of 'selection' over generations of these occurances?? Perhaps god was helping out?

 

DAK

[TeleMad]

<during drought years the smaller and feebler beaks were less fit and the larger beaked birds outreproduced them; then when the drought was over, the small phenotype was no longer as strongly selected against and increased in frequency.>

 

Wonder what the math is on the possibility of 'selection' over generations of these occurances?? Perhaps god was helping out?

 

DAK

 

Well golly gee whiz, I guess...and in the same way, I suppose everything could be God doing it ... yeah, when I throw a light switch it might not be electrostatic attraction and repulsion that pushes the electrons through the wire, as science foolishly believes, but God. Hey, that makes God my slave! I command him, and he must obey!

[DAK]

<Well golly gee whiz, I guess...and in the same way, I suppose everything could be God doing it ... >

 

Well, as quantum mechanics suggests, all Newtonian causation just could be a fallacy. The very observations/attention of the observer creates the possibilities.

 

<when I throw a light switch it might not be electrostatic attraction and repulsion that pushes the electrons through the wire, as science foolishly believes, but God.>

 

electorstateic attraction and repulsion don't mean bubka without wire and someone to flip the switch! LOL, perfect example.

 

<Hey, that makes God my slave!>

 

Hmmmm, why did you flip the switch again??? ROFLMAO!! That's called the 'ego' that necessarily [as it's nature] believes all is at it's beckoned call. God would be behind the ego somewhere, trying to shine through... ;))

 

< I command him, and he must obey!>

 

He? You mean it? Obey? No that would be causality again... you have to make the 'Quantum Leap'... sorry. BTW, you'd simply be part of god if defined as the unified field... so it would be beyond the your/our {linear} mental capacity to comprehend... by definition. Like a fish comprehending water if it's never flopped about on the beach for a time. :Alien:)

 

DAK

[TeleMad]

I'm sorry DAK, I didn't realize you were baiting a trap for me; trying to work in your silliness somehow in what appears to be a legitimate way (responding to someone else ... after setting the trap). If I had known that, I wouldn't have poked fun at your really silly statement.

 

Now, are you done diverting the discussion from the scientific topic of Chance and Evolution?

[infamous]

I'm sorry DAK, I didn't realize you were baiting a trap for me; trying to work in your silliness somehow in what appears to be a legitimate way (responding to someone else ... after setting the trap). If I had known that, I wouldn't have poked fun at your really silly statement.

 

Now, are you done diverting the discussion from the scientific topic of Chance and Evolution?

Aaah, but you fell into it, didn't you? If you hadn't strayed yourself, maybe that could have been avoided.

[bumab]

Yeah, It's like kids trying to keep each other quiet. They make so much noise trying to shut the others up, they actually make the problem far, far worse.

 

Back to the topic-

 

Serial computations are valid to a study of evolutionary probability, since the mutations must occur in order and they all build on one another, so obviously, they need to occur in the same individual. HOWEVER, it does not have to be serial in an individual and that individual's direct offspring, but rather the breeding population. Successful mutations will dissemenate into the breeding population around the origional mutation, thus every calculation must also take into account the thousands to millions of times the next mutation has to get going EVERY generation.

 

So, it gets a little easier :Alien:

[TeleMad]

Serial computations are valid to a study of evolutionary probability, since the mutations must occur in order and they all build on one another, so obviously, they need to occur in the same individual. HOWEVER, it does not have to be serial in an individual ...

 

So it must be X, but it doesn't have to be X?!?! Clear as mud.

[bumab]

Good point. Allow me to rephrase:

 

Many "odds" arguments against evolution (on this site and others) are based on serial mutations lining up in a single individual. The entire breeding popoulation needs to be considered, since succesful mutations will disseminate rapidly. This decreases the odds dramatically.