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.
Of course evolution is going forward. That is to say, it is going forward in time.
Yes, I agree with Gould.
Would you agree that, without speculating on how it comes about, convergent evolution as observed points to a channelling of evolution along specific routes? What are yout views on this?
An example would be endothermy in birds and mammals as detailed here. They speculate on “just so stories” to account for the facts of these convergences.
They say:
The characteristics mentioned above allow birds and mammals greater freedom from the surrounding environments over their more basal diapsid and synapsid precursors.
Channeling? No. It’s just similar problems leading to similar solutions (for some meanings of “similar”). There’s nothing particularly surprising about this.
The simplest explanation IMO is multiple starting points.
Of all the lineages that have evolved, only one (the hominims) have developed the sort of consciousness you’re talking about. And of many “experiments”, only one of perhaps dozens of tries has actually succeeded – if we measure success in terms of rendering ourselves extinct in record time. Evidence suggests that our species has barely, perhaps luckily, survived one or more bottlenecks when only a few hundred individuals were alive at any one time. There’s no evidence that had our species died out like all our close relatives, any other would have taken our place.
I’m with Gould all the way.
Is it? I mean what evidence is there that would outweigh the vast amount of consilient evidence that indicates branching from a common origin?
Convergence arises when different lineages adapt to similar niche and lifestyle. It happens because of evolution. That’s not speculation, it’s a fact.
Alan Fox,
What is a common origin? Common design :-). There is no evidence that reproduction and associated variation can re create a sequence. Convergent evolution should have been a show stopper for the theory.
You cannot explain this with your extremely tentative lots of needles in the haystack hypothesis.
A somewhat intriguing case of parallel evolution is intelligence, which evolved twice, in vertebrates and cephalopods. The last common ancestor of vertebrates and cephalopods would have a very simple worm-like animal prior to the split between protostomes and deteurostomes..
Yet your ID fantasies… They explain nothing. Your sole argument, such as it is, amounts to denial. It gets boring.
.
Why are you having to invoke a labeling fallacy?
On the contrary ID provides a method to discover design in nature. Like the gene coding sequences that appear in separate animals that do not exist in the common ancestor. I am sure given the age of the universe you can come up with a natural “just so” story how this occurred like labeling it convergent evolution.
I do agree your repetitive ID denial could be boring but its actually entertaining. Your use of a labeling fallacy kept it fresh. 🙂
This, of course, is NOT an example of the “labeling fallacy”, because Bill says that it isn’t. Okay?
But I am curious Bill: how many needles are there in the haystack? Specifically, how many different 80 amino acid sequences are there that will bind ATP?
How does this number compare with the number of baryons in the observable universe?
Keep on keeping it fresh, baby.
A much better book on convergence is Improbable Destinies by Jonathan Losos. He considers the conditions under which we expect convergence and the conditions under which we don’t using largely experimental data. Needless to say, Charlie’s speculations are not supported.
everything gould said was a waste of effort and a humbug. Only the introduction of PE was of a useful thing and this only a recognition of evolutionism being a failure of the fossil record mattered.
if you have mutations johnny on he spot then you always can say they can go any where in results. its just a line of reasoning bereft of actual scientific investigation.
But the only way you’ve come up with to discover design in nature is to point to this or that and say “Look! See! Design!” And how do you know? Because you knew it was design before you looked. ID is the mother of all Just So stories. It “explains” absolutely everything, all with the same “theory”. And adds no explanatory power to anything.
If anyone is arguing that there is a general trend in evolution toward convergence, or a general trend toward increasing “complexity”, then they need to present their definitions, together with a statistical argument verifying their proposed trends. I don’t see any such argument here. Without that, these are nothing but anecdotal imaginings.
Since the early days, when Dembski flaunted his filter and Behe claimed evolution couldn’t happen because “irreducible complexity”, it has been ever thus.
I’ve just found a book called, “Convergent Evolution – Limited Forms Most Beautiful” by George McGhee, which looks quite interesting. Perhaps you would be more accepting of “limiting” in place of “channelling”. Or maybe not. 🙂
In my opinion living forms come from an underlying unity. But the unity is not in the ancestors it is in the archetype which is not dependent on linear time.
Please give us an example of identical genetic sequences that appear in two different animals and that are completely absent in their common ancestor.
Thank you for that suggestion!
The only argument I’ve seen that carries any weight with me is Stuart Kaufman’s work on increasing number of cell types across metazoan evolution.
And hell that could just be a fun fact about metazoans. Are angiosperms more complex than algae? I dunno. Sure it seems that way to me, but I’m not a botanist and barely even a biologist. (My BA is in Biology, that’s all.)
Flint,
Any argument can be challenged with a straw-man. Use Behe’s direct definitions and I think you will struggle.
Kantian Naturalist,
Probably a difficult challenge but if the sequences are 90% similar (90% common nucleotide positions) and evolving separately do you think that substantially changes the argument?
DNA_Jock,
Given the calculated odds of ATP binding assuming 10^11. How long would it take this feature to get fixed in a population of say 10000 animals? Under 13 billion years? Statistically impossible to fix with nearly neutral mutations? Requires strong selection and blows neutral theory out of the water?
Keep it fresh 🙂
You mean the definitions that have changed constantly, and have now been reduced to Behe’s demand that every mutation that has ever occurred be thoroughly documented?
I am still amused by the scene of Behe sitting on the witness stand claiming that the immune system could not possibly have evolved, AND complaining that the 3-foot-high stack of books and papers detailing the evolution of the immune system they put in his lap were too heavy! But none of them met his definition of evolution, itself subject to mutation and evolution to evade factual arguments.
You need to find a more recent charlatan. Behe’s 15 minutes of fame are long expired.
Flint,
None of them were mathematical models demonstrating feasibility. Evolution does not have an answer to how new biological features like blood clotting arose. It has nothing to do with Mike’s definition of evolution.
That’s not how it works. Mathematical models can be wrong. The mathematics might be right, but the modeling can be wrong.
Strong empirical evidence trumps mathematical models.
Neil Rickert,
Strong empirical evidence for what specific hypothesis? That the DNA sequence that helps build the blood clotting hypothesis evolved?
What does it say when you are unable to create a model that would support your hypothesis? Without a mathematical model how is your claim predictive?
The reality is that evolution is assumed to be true in science. There is a standard claim of “mountains of evidence”. IMO this is simply rhetoric to cover for a lack of any viable mechanistic explanation for systems like blood clotting.
The mountain of evidence is easily explained by separate origin of species as discussed in Genesis 1. With the special creation hypothesis the modeling begins to work as population genetics assumes the pre existence of the population.
I asked how many different 80 amino acid sequences there are that bind ATP.
Bill wrote back:
Difficult to parse this sentence fragment. The best I can come up with is that Bill reckons ATP binders constitute one in 10^11 of the 80mers in Keefe’s library. Which isn’t far off. But I asked the reverse question, “how many different 80 amino acid sequences there are that bind ATP.”
Remember, Bill, you claimed “You cannot explain this [??] with your extremely tentative lots of needles in the haystack hypothesis.”
How many needles are there in the haystack, Bill?
Bill continued
Word salad.
Hint: there are about 8 x 10^67 different ways to arrange a standard 52-card deck.
DNA_Jock,
Fun fact. Given that what is the chance of getting the exact bridge hand twice in a row.
Hint: This has nothing do with how many possibility combinations there are.
No…. just the mathematical problem of fixation. I would not address it either if I were in your shoes. 🙂
Yes, that’s right. It is assumed based on a huge amount of evidence.
The evidence is there. You are attempting to explain it away because you don’t want to accept the obvious conclusions.
colewd,
Math, U r doin it rong.
Also, using blood-clotting as your example of something unevolvable seems a terrible choice. What makes you think there is no viable mechanistic explanation? What efforts have you made to independently verify the sources you are relying on?
Please be very specific, about both your sources and your research to corroborate.
Yes, evolution has that answer. BUT not according to Behe’s definition, since Behe defines evolution in a way that it does not and cannot happen.
I’m reminded here of Axe and Gauger, who define evolution in ways hilarious to any qualified biologist, claim that if evolution (their definition) were true, we’d see (something preposterous). Then they do truly skilled and meticulous lab experiments to demonstrate that their preposterous results do not happen. Thus disproving evolution!
And you imply definitions don’t matter. But if blood clots and Behe claims this is impossible according to his definition (and therefore goddidit), a reasonable person might suspect Behe’s confusion has more to do with religion than science.
It is 1, divided by the number of combinations of 52 objects taken 5 at a time.
So of course it has to do with combinations. (Maybe not “possibility combinations”, whatever that means).
So the “hint” is wrong.
If we look at the earthly biosphere as a unit and accept the story of evolution whereby life gradually diversifies from relatively simple beginnings, we can think about the events and changes which have had significant impacts along the way.
A selection of these would be the great oxidation event, the appearance of multicellularity, transitions from aquatic to terrestrial living, attributes which gave living systems more freedom from the environment such as endothermy and motility, nervous systems which facilitated conscious sensory experiences. Would you deny that these are novelties which have emerged during the course of evolution? Looking back we can see that many novelties have come about in multiple lines. Humans are the first to develop self-conscious rational thinking but that does not mean we will be the last.
So we can say with a fair amount of confidence that life diversified, life developed motility, life emerged from the oceans and life is developing higher forms of consciousness. These are a few of the major novelties which appeared throughout evolution. Life emerging from the ocean was not just a single event.
Can you give any examples of life experimenting and failing to attain novelty?
So it’s a case of it just happening because of evolution. What does that actually tell us?
Take a specific example Interplay between Developmental Flexibility and Determinism in the Evolution of Mimetic Heliconius Wing Patterns. From the summary they say:
Although there was rapid genetic diversification, phenotypes are channelled down specific paths by natural selection.
More from the article:
WntA itself is highly conserved across the entire genus but the regulatory pathways associated with this gene are extremely diversified. And it is the regulation which has a measure of control of wing patterning.
It is easy to say evolution did it. But how did evolution do it? That is not so easy to determine.
Convergence only refutes common descent if one completely ignores the rest of the genome. And, indeed, ignores the fraction of the genome involved in the feature of interest as well. Good job we have two hands, one for clapping over each eye.
Fine examples. I would also grant high intelligence to living beings such as insects and plants, but not the individual intelligence demonstrated by some vertebrates and cephalopods.
How much communication is taking place in the average forest? Communication that is only recently being discovered.
Thanks for the reference. I see he’s a great fan of Lenski’s long term experiment. I’ll need to take a closer look at what he has to say.
So smart plants have more intelligence than dumb squid? How about air, always smart enough to move toward lower pressure. Or rain, smart enough to fall? Or rivers, able to create truly complex watersheds? All of these strike me as smarter than at least one vertebrate.
I would say the general trend is towards diversification in the same way that the development of an animal from a single cell involves differentiation into the various cell types.
But we can point to instances of convergence such as between marsupials and placentals. We know that marsupial moles are more closely related to kangaroos than to golden moles. It’s okay to say that the similarity is due to them having similar lifestyles but there needs to be ancestral individuals with attributes which progressively lead to the observed forms.
I am always wary of statistics. 🙂
Convergence and common descent are not rival theories, they are both observed facts. Ichthyosaurs and sharks may have converged on the same streamlined shape but this would not be attributed to common descent even if they are thought to have descended from a common ancestor in the remote past.
Can you read this article and tell me what you think?
DNA_Jock,
What do you think a mechanistic explanation is?
I was referring to Bill Cole’s notion that convergence argues for multiple origins.
Joe Felsenstein,
You are right.
The correct hint is: This has nothing to do with how many solutions there are (Fox needle’s in the haystack). Is it time that Behe’s arguments should be taken seriously?
CharlieM,
They are mechanistically completely distinct, so I don’t know why one would think them connected.
Allan Miller,
Convergence along with other evidence suggests separate origins or more than one starting point. As Charlie says common descent is a fact. The debate is over the number of starting points. Here is additional evidence of multiple starting points that you may have seen.
http://www.sci-news.com/genetics/article01036.html
The editor is not longer working for me.
colewd,
Nor for me. Have changed the plugin. Please use moderation issues thread for letting me know if this solves the issue.
colewd,
No it doesn’t.