Does evolution repeat itself? Could evolution repeat itself? Where do people stand in relation to the thoughts of Gould and Conway Morris?
Gould has a point, everything is in a state of becoming. As Heraclitus would say, all is change. Replay the tape and nothing would be the same. But would or could there be any similar trends? Would life in general proceed in such a radically different way that Gould makes out?
From “Life’s Grandeur”, Gould states:
“…no persuasive or predictable thrust toward progress permeates the history of life…
“Wind the tape of life to the origin of multicellular animals in the Cambrian explosion, let the tape play again from this identical starting point, and the replay will populate the earth (and generate a right tail of life) with a radically different set of creatures. The chance that this alternative set will contain anything remotely like a human being must be effectively nil, while the probability of any kind of creature endowed with self-consciousness must also be extremely small.”
Conway Morris disagrees with Gould’s conclusion. He champions an inevitable path and cites convergent evolution as evidence which suggests this.
In “The Crucible of Creation” he states,
“What we are interested in is not the origin, destiny, or fate of a particular lineage, but the likelihood of the emergence of a particular property, say consciousness. Here the reality of convergence suggests that the tape of life, to use Gould’s metaphor, can run as many times as we like and in principle intelligence will surely emerge.”
I’m interested in what people have to say about this and its relation to topics such as the emergence of bilateral symmetry and differentiation from head to tail, extreme specialization, encephalization, endothermy, caring for young, transitions from aquatic to terrestrial living and other related topics. These processes have occurred multiple times in different lineages over time.
Allan Miller,
Solid rebuttal 🙂
I guess you have a solid handle how all the different vertebrate genes got fixed in separate populations uniting vertebrates to a single tree. Brilliant 🙂
The “correct hint” is a hint for some other puzzle. As such, for this question (hands in bridge) it is just as incorrect as the first hint. It is simply an attempt to distract.
As I see it Behe claims that the blood clotting cascade, or part of it, is irreducibly complex and therefore it cannot have come about through a series of slight, successive beneficial modifications. It would have to have been acquired by a “hopeful monster” scenario and the chances of this happening are so small as to be for all intents and purposes impossible.
Can you elaborate on where you think Behe is confused about this?
Wait, you think common genes are convergent features? Isn’t that rather begging the question? Certainly not how convergence is conventionally viewed, so yeah, I’ll stick with “no it isn’t”.
“Convergence (by which I mean absolutely anything held in common between two groups) indicates multiple origins”?
Joe Felsenstein,
Your model to how similar sequences evolve separate from common descent is? The separate origin model explains this.
Allan Miller,
Now the logical fallacy game? Wait…here is my straw-man. And Felsenstien accused me of creating a diversion 🙂
Behe’s mistake is to begin with the correct thought that a complex system cannot be assembled piecemeal, and then wrongly conclude that therefore some intelligent agent is necessary to do the assembling.
What he misses is the idea that complex functionally integrated systems emerge from simpler functionally integrated systems.
Precisely. And in the case of the blood-clotting cascade we have terrific examples of those simpler systems, which confuses Behe no end.
DNA_Jock,
Your pivoting off KN’s assertion. Were is the feasibility model? You need to show how you get from sequence A that builds secretion injection to a mobility motor.
Is confusion the new label replacing TSS :-).
I think the main problem is your utter lack of clarity. Perhaps you could actually explain why convergence indicates separate origins – bearing in mind how convergence is detected.
Allan Miller,
Simply the independent origin of similar sequences where common descent is not clearly identified. You can also see them in the Venn diagram I posted along with thousands of de novo genes per vertebrate kind. This is evidence of separate origins of the individual species created by God.
Not for any sane definition of evidence, it isn’t.
You need to be able to identify identical sequences in species where common descent is clearly absent, not merely not yet clearly identified. And the identical sequences need to be absent in the last common ancestor, not merely present but not expressed.
For example, we know that the last common ancestor of cephalopods and vertebrates was an extremely simple worm-like animal with a rudimentary brain. Yet both cephalopods and vertebrates are highly intelligent animals, esp when it comes to manipulating tools.
If the genetic sequences underlying tool-use are identical in octopuses and crows, despite the absence of that sequence in the worm-like animals they evolved from, then you would have a nice piece of evidence for the account that you want to give.
Or, to take another example: we know that endothermy evolved twice, in birds and mammals, from an exothermic common ancestor. Do birds and mammals use the same genetic sequences? Do we have reason to think that those sequences are absent in the last common ancestor?
Gross morphological similarity, as between ichthyosaurs and cetaceans, isn’t going to work as the kind of evidence you need — that can easily be explained in terms of similar adaptations to similar niches. You need evidence that can only be explained by positing the existence of intentional agents that engage in genetic engineering at certain points in the evolutionary process.
Huh? Are you accusing me of a gymnastic move? I take this to mean “You are changing the subject, away from what KN was asserting.” which is obviously false. Let’s go to the tape:
Charlie writes
Charlie is correct that Behe views the [human, heh] blood clotting cascade as irreducibly complex, and therefore unevolvable (although his “as I see it” and the “or part of it” are cute). KN responds, quoting Charlie, and notes
So KN clearly includes the blood clotting cascade in the set of such systems. It’s the topic of this sub-conversation, silly.
Have you developed an infeasibility model? We would love to see it — you guys are forever promising us a really nice shiny infeasibility model, but you never deliver.
Not so much a ‘pivot’, more a ‘giddy up’. LOL
Well, it’s looking like more of an add-on, if you get my drift…
Kantian Naturalist,
It is exceeding unlikely a similar sequence would form and get fixed in a new population independently.
The diagram I posted previously makes it highly unlikely that all vertebrates share a common ancestor. Getting thousands of functional changes to DNA fixed is not reconcilable mathematically based on current mechanistic explanations.
. Your assumption (they evolved from) is not a likely
starting point.
I think the multiple origin hypothesis is much stronger at this point. The assumption of a common ancestor between two species is a very poor assumption given current molecular evidence unless the gene families are highly similar such as coyotes and dogs.
DNA_Jock,
The word un evolvable makes this a straw-man argument. Difficult for current evolutionary mechanisms is closer.
Cute burden shift 🙂
I think its time for all of us to move past the use of logical fallacies. KN is very disciplined in avoiding them.
I don’t understand this claim. Aren’t you arguing that Behe is saying that his god MUST be responsible, since there is no viable evolutionary pathway to produce the blood clotting mechanism? “Difficult” doesn’t mean impossible, and Behe’s god is not required for difficult, only for impossible.
Oh the absurd irony, Bill. I’ve been following recent interactions at Peaceful Science between you and John Harshman and Puck Mendelssohn.
https://discourse.peacefulscience.org/t/general-discussion-on-id-god-and-evolution/14023/194?u=alanfox
Yet you haven’t said anything about convergence.
Do you think that the field of evo-devo is a complete waste of time? Do you see no connection between an individuals development and its evolutionary history?
He doesn’t miss that. He is asking for details on how these systems emerge in the first place. As in his mouse trap example, a system can be both simple and irreducibly complex.
And irreducibly complex systems can be nested.
No. Wherever did you get that conclusion?
You’re doing a switcheroo. The analogy was between diversity at within-individual and between-species levels.
Clearly, the developmental arc of a current individual in a lineage is the culmination of its prior evolutionary history. That does not make the processes of evolution and development of a single individual closely comparable.
Suppose individual development consisted of growing an undifferentiated blob of cells, and species diversity consisted of many blobs of varying size and colour. Prior states involved smaller blobs at their developmental apex, ‘recapitulated’ in modern forms as an inevitable intermediate smallness. Evolutionarily there is divergence, but individually there is not. Whence the connection now?
Have you read Darwin’s Black Box? Behe discusses Doolittle’s scenario of clotting evolution from simple beginnings. Behe’s book, “A Mousetrap for Darwin”, is a more comprehensive answer to his critics which I’m sure goes into greater detail on the questions posed by blood clotting, but I haven’t read it as of yet.
Below is a diagram from this article by R.F. Doolittle. You will notice that fibrin production in the lamprey, though simpler than the mammalian system, is an irreducible system.
CharlieM,
But ‘other vertebrates’ is also an irreducible system. Despite being clearly reducible, as witness lampreys. Render lampreys extinct, and we erase all knowledge of simpler systems.
Allan, I suspect, will note no such thing. I certainly don’t see how you get to “is an irreducible system” from that diagram. Can you explain why you assert that the blood clotting system could not have evolved by a process of selected variation?
Behe’s thinking evolves.
From In Defense of the Irreducibility of the Blood Clotting Cascade: Response to Russell Doolittle, Ken Miller and Keith Robison Behe wrote:
He recognizes how thinking about processes rather than parts gives a more accurate understanding of reality.
He amends his definition of irreducible complexity as follows:
This is a shift from thinking about parts as static entities to thinking about steps as dynamic processes in which the parts are involved.
Now if could get beyond the machine metaphor..:)
If Behe had been able to get beyond the machine metaphor, he would not have become an ID theorist.
I wonder how ‘the wisdom of nature’ deals with the irreducible complexity problem? 🤔
So you all say. But Behe said the same thing about the entirety of the human system in Pandas, until his critics pointed out the problem with that line of argument.
As Matzke put it:
Hence my allusion to the “human, heh” blood clotting system. It’s a massive own goal.
It’s quite simple. The Wisdom Of Nature increases the frequency of the right allele at gene 1, all the way to fixation, in spite of this allele having lower fitness. Then the same for the right allele at gene 2, and then gene 3, and so on. And after gene 10, the irreducibly complex structure is there, and the W.O.N. can finally collapse in exhaustion, having fought natural selection all the way.
DNA_Jock,
The linked Pandas Thumb article written by Nick Matzke is worth a read for those whose memories of the heady days of ID’s retreat from Dover need refreshing.
Bipedalism is a convergent trait. It has evolved more than twice in archosaurs, it evolved convergently in the crocodilian and bird lineages. Birds and humans have independently arrived at obligate bipedalism. All dinosaurs are thought to have descended from fully bipedal ancestors.
Within extant animals, bipedal hopping is most prevalent in mammals, having arisen once in marsupials and five times independently in rodents, three separate times in small desert rodents.
Some lizards use bipedalism while running and even cockroaches have been observed to do this.
An evolutionary trend towards bipedalism is in evidence.
But humans are unique in that our bipedalism and upright posture has freed our upper limbs completely from having to provide locomotion save the very occasional rock or tree climbing. This along with several other traits allows us the freedom to create art, tools and external means of communication. Other animals which have evolved bipedalism have done so in a more restricted, one-sided way.
When you said, “They are mechanistically completely distinct, so I don’t know why one would think them connected”, I took it that you regarded the sole way in which entities could be connected was mechanistically.
Then I would say that the growth of the undifferentiated cells was a primal process which had the potential to differentiate but had not yet advanced to that stage. Species can only diversify if individuals diversify. I would ask when and how did the diversity between the species of blobs arise. Were they always separate? Did they originate from a common source?
I don’t think that the concept of individuals and of species should be the same between prokaryotes and higher multicellular organisms. There is a far greater degree of multiplicity within an individual mammal than within an individual bacterium.
Each system is suitable for the animal to which it belongs. The lamprey system cannot be reduced in the lamprey. For example remove the thrombin from the system and there will be no clotting. And it is the same for the human. But each system is specific to the animal in which it belongs. We can see that the human system is more complex than the lamprey system but no details are given as to how this increase in complexity is added. An extra step cannot be inserted with just a single protein. All the associated correct expression factors must also accompany the activating protein. In other words the extra step itself is irreducibly complex. As Behe writes, “From the beginning, a new step in the cascade would require both a proenzyme and also an activating enzyme to switch on the proenzyme at the correct time and place.”
See my post above.
Try removing any of the items labelled in the diagram and explain to me how the blood will still form a clot.
Probably not, but he might still have been an ID sympathizer.
We can observe how human intelligence is involved in the production of machines.
Somebody thought about how a standard mousetrap could be constructed. The parts were manufactured and put together. Add the bait, set the trap and it will probably kill any mouse that trips it.
Irreducibly complex systems are quite achievable for intelligent minds.
Possibly. I think that once you stop seeing life through a mechanistic lens, and start taking seriously the metaphysics of emergence and how teleology is an emergent feature of self-organizing systems, one ends up seeing ID as the wrong way of asking the right questions.
That was the conclusion I reached years ago.
So on strictly intellectual grounds, I could regard myself as sympathetic to ID — seeing as asking the right questions (is teleology real? where does biological form or organization come from?) but misled by the mechanistic mind-set into assuming that complex organization requires a top-down assembly process by some intentional agents.
Where I become implacably and completely hostile to ID is when it comes to ID as part of a comprehensive political project that I consider not only reactionary but basically fascistic.
CharlieM,
Doolittle covers this. Basal vertebrates, Amphioxus and sea squirts, don’t have clotting systems at all but manage just fine. You’re looking in the wrong end of the microscope.
Are you saying the “wisdom of nature” is synonymous with ID creationism’s Intelligent Mind? Do you believe the evolution of organisms to be determined by interventions of a Mind capable of foresight and planning? Will you be defending this stance?
That was just so familiar: the poor grasp of comparative biology, the constant updating of definitions to avoid conceding defeat, the assumption that one’s personal ignorance represents the scientific status quo. Where did I see this before?
He doesn’t argue that partial systems will be non-functional. He argues that removing essential parts from specific systems will render them non-functional. The simpler system of the lamprey is still a complete specific system.
As I said previously irreducibly complex systems can be nested.
Expression of any single gene is an irreducibly complex process requiring several factors working together to produce the resulting protein.
Behe refrains from labelling extrinsic and intrinsic portions of blood clotting as irreducibly complex because it is difficult to determine how these pathways proceed and if alternative routes could be taken. They cross over at several points. That is why he restricts the irreducible complexity to after the point where factor X is activated.
By the time he wrote “Darwin’s Black Box”, he would had spent more time researching and thinking about the finer details of the system. It is a more comprehensive treatment of the system. It is easier to argue against his initial thoughts on the system than arguing against his more considered and mature thoughts on it in which he clarifies his meaning.
The wisdom lies in the construction of these genes and associated coordinated expression in the first place.
I wonder what Behe has to say about this in his book, “A Mousetrap for Darwin” and if Matzke of Miller will respond to the book?
No, irreducibly complex systems cannot be “nested”, as the simpler system demonstrates that at least some subunits of the more complex system are redundant to perform given function.
i agree that proposing a top-down assembly process by some intentional agent or agents seems too much like human creations and inventions where the agent is external to the product. Interference from without.
And the practice of any so called science should not become political.
I don’t really care if Behe thinks the the creative agent is God or some alien mad scientist, I just look to see if the concept of irreducible complexity has any merit. I believe it does.
Why would amphioxus need a clotting system when it doesn’t even have a system of blood flow? They do not have a heart and lack a circulatory system. Oxygen diffuses from the gills into the front part of the body through osmosis and a structure called an atriopore mediates the supply of oxygen to the rear of the body. No need for circulating blood and so no danger from a lack of a clotting cascade.
And Sea Squirt Regrows Entire Body from One Blood Vessel. With an ability like that why would it need to worry about a little blood loss?
But thankyou for inspiring me to learn some more details about these animals. 🙂
Say what? Of course he does. That is what “irreducible” means.
“essential”? What a silly tautology! He argues that removing any part from an IC system will render it non-functional.
Yes. So his original Pandas claim that the human system is “irreducibly complex” is seen to be a God of the Gaps error. That’s why he retreated to the “irreducible core” position, and hoped that the rubes would not notice that his argument is torpedoed when IC becomes a function of our ignorance.
No I’m not saying that. I’m talking about intrinsic group intelligence.
To give an example from personal experience, I consciously learn things through individual intelligence but I was born with an innate, instinctive intelligence shared by all normal newborns. This is more like the group wisdom I was referring to. There is a higher wisdom at the species/kind level than is apparent at the individual human level.
Well, he does have a habit of misrepresenting critics whilst adjusting his argument to obscure the criticism, but “By the time he wrote Darwin’s Black Box” he was still claiming Christmas Factor etc. were part of the essential irreducible system. That’s Factor IX, Charlie — not seen in the lamprey.