In Why Evolution is True, Jerry Coyne writes that gradualism is one of the six tenets of “the modern theory of evolution” (which he equates with Darwinism – see page 3).
Eugene Koonin writes that the tenet of gradualism is known to be false (The Logic of Chance p. 398).
Yet gradualism is obviously still quite popular here in “The Skeptical Zone.”
Surely gradualism is not a logical requirement or entailment of the theory of evolution. Neither is it supported by the evidence.
So given what we know about evolution, why do evolutionists still cling to gradualism? My suspicion is that the alternative smacks too much of miracles. So gradualism is more of a religious conviction than a scientific one.
What is the evidence for and against the gradualist hypothesis?
Something that just occurred to me after reading Glenn’s reference to molecular clocks. Is it even reasonable to believe in saltation and (the evidence of) common descent at the same time?
Here’s a graph where I try to show that, if one doesn’t assume gradual change, phylogenetic evidence can’t support humans share a more recent common ancestor with chimps than gorillas. Something similar could be done with every other node of the tree
Link to a higher resolution image:
http://theskepticalzone.com/wp/wp-content/uploads/2017/07/saltation-768×354.png
Yeah, I think you’re assuming that phylogenies are inferred based on molecular clocks and overall similarity. They are not. Saltation would have no effect on phylogenetic inference under almost all models in use, i.e. all models that don’t assume a clock.
So our phylogenetic models would be able to detect the above saltation event? or would they predict that humans and chimps diverged more recently than humans and gorillas, just like they do now?
Note that the saltation proposed would imply that somewhere along the gorilla lineage, they would be producing descendants that would look very much like humans, with genomes much more similar to chimps
I guess you mean that there could be saltations within the predicted lineages like these below?
Saltation isn’t the problem in your scenario. The problem you seem to be trying to show is massive convergence, i.e. a saltation event that transforms the human genome into something we would expect from a chimp relative. That’s quite a different thing. Yes, truly massive, consistent convergence would fool everyone.
Saltation, on the other hand, is just an extreme acceleration of evolution. Phylogenetic analysis doesn’t deal with how long events take, just the amount of change expected on a branch. The length of a branch is not a length of time, and rates could be varying wildly along that branch for all it matters.
Thanks John. Perhaps some context is in order.
All I’m trying to do is to address Mung’s question from the perspective of a rather uninformed layman like myself. And the question is, why gradualism? Why not believe large saltation events can produce what IDists claim gradual change with the aid of natural selection can’t?
Mung seems to believe we have no better reason to think that most transitions happened gradually rather than in one wild saltation event: that gradualism is just an unsupported a-priori of evil atheist evolutionists.
So the question is, if we must contemplate the possibility of those weird transitions, why restrict them to the lineages drawn by phylogenetic trees? Wouldn’t that also be an arbitrary a-priori restriction to the model? But if we give equal footing to saltation accross lineages as saltation within lineages, what reason is there to accept phylogenetic trees as evidence of common descent?
IMO the main problem with Mung’s argument is that he keeps equivocating: he argues that gradualism can’t do the job (of building complexity), or at least there’s no good reason to assume gradualism is a better explanation than saltation. Let’s keep in mind that the kind of saltation he proposes must be able to produce complex systems like eyes, brains, skeletons… in a single generation! because what good is half an eye after all? So when he mentions HGT, whole genome duplications and other known mechanisms, he’s ignoring the fact that none of those can produce the kind of absurd saltation he must support. Not even close! But Mung, being the great word lawyer he is, will have us believe that if he can somehow get the word saltation in the same paragraph as HGT or whole genome duplication, his ridiculous saltationist model is now supported or even reasonable.
But what about molecular clocks? If we allow the kind of saltation events that will skip millions of years, or even hundreds of millions of years of gradual change, shouldn’t proponents of such a model be forced to correct divergence times? These saltation events would amount to the kind of hyper-evolutionism Mung rejects and even mocks when he rejects YEC’s assumptions. In fact, one could argue that those saltations may very well support a much faster evolution than inferred by molecular clocks, and therefore, that the entire evolutionary history might have happened in just a few thousand years.
Mung is a closet YEC, he just doesn’t know it yet
Only when in your hands dazz.
When a new gene shows up in an organism, and it wasn’t there before, is that a “saltatation” as you are using the term?
I think that this discussion needs to distinguish between the genes that affect particular morphological characters that we use to see whether chimps share traits with humans, and other parts of the genome.
Traits could be undergo bursts of change, or be convergent, due to selection pressure, without any acceleration of the molecular evolution of the remainder of the genome, and without any convergence in the sequences in that remainder. There would be no change in the overall molecular clock, and molecular phylogenies would not be affected by the convergence.
Another issue that needs to be discussed here is that theories of saltation based on genomic changes are actually talking about the origin of a single individual. Or, if the changes happened in the gamete produced by one parent, in half an individual.
The change then needs to somehow spread through the population. If the genome rearrangement has any disadvantages (such as breaking down when there is recombination with the original chromosome) then it can only spread by being strongly enough favored by natural selection. Unless it is in a very small population.
And the process of spread might not be saltational, but could be quite gradual. This whole populational aspect of theories of saltation is usually omitted, as people wave their hands furiously.
I am thinking of some of the people involved in “third way” theories. One of them, Eugene Koonin, has argued the importance of saltational events, but unlike the others he is well aware of the need to consider population genetics, and will ultimately face these issues.
The explanation is simple. First, we suppose gradualism because the evidence shows that’s what happens. The fossil record, when it’s good enough to preserve the structure in question, shows gradual change. The evolution of the mammalian middle ear has already been used as an example here. Genetic comparisons among species show the gradual accumulation of point mutations, indels, and less common mutations. Second, we suppose gradualism because the simultaneous, instant appearance of all the elements of any complex structure, at the genetic or phenotypic level, is much less likely to happen than the sort of gradual buildup we see.
Now, the sort of transition you propose in your example, in which the entire human genome decides to switch from resembling a gorilla’s to resembling a chimp’s, has no credible mechanism other than, I suppose, the decision of an insane god to deceive scientists, if you want to call that credible. I think we can discount it.
And again, the problem with that isn’t saltation, per se, it’s massive, coordinated convergence. I really think it’s irrelevant to the issue Mung tries to raise.
Yes, if divergence times are based on a molecular clock. But of course that’s the case for any variation in evolutionary rate, not just saltation. And in fact there are methods intended to do just that: take a tree with varying branch lengths and attempt to calibrate them to time. In order to do that, one must have anchor points on the tree. The present is a collection of such anchor points, and fossils are generally used as others.
Here is an example:
http://www.cell.com/current-biology/abstract/S0960-9822(13)00916-0
I don’t think any of this is relevant to Mung. All he wants to do is attack evolutionary biology by any means convenient to the moment. I don’t think he has any alternative in mind. Or if he does, he isn’t saying.
For the emptienth time, I take saltation to mean a single transition where complex systems or organs appear fully formed, from scratch. And that’s because that’s what you must believe happened if you assume gradualism can’t do the job.
Do you know of any mechanism that will produce “a new gene” and, as a result, the complex structures that you think can’t evolve gradually would emerge?
I wonder if Mung is imagining a “gene for eyes” or a “gene for livers”. Hard to tell, because he apparently won’t say. I’m at some disadvantage because I only see what he says when someone else quotes it.
I keep recalling what I believe sparked this talk about saltation. It was the thread about Paul Nelson arguing that a single mutation in HOX genes (or those affecting early embryological development) would produce a cascade of disruptions in the process of embryo development, making it an evolutionary dead end.
I argued that, if one believes in CD, and also that a single mutation in HOX genes must be lethal, the only alternative is a bunch of those mutations happening all at once, and of course a bunch of other coordinated regulatory mutations necessary to bridge the big gap from ancestor to descendants, who must now be radically different organisms.
Seems to me the same applies to the eye: it’s an evo-devo thing: you don’t just “crocoduck” the genome to have an eye pop out of nowhere in the descendant of an otherwise identical organism. Ironically it’s the very argument they use all the time that makes the transition unbelievable: you would need a ton of other coordinated changes in the genes and the developmental process to make it work: you need nerves, some structure to hold the eye in place, etc…
In the end you have an argument for the impossibility of small changes, to then conclude that many many more of them must be the solution.
*slow clap*
I’ll let him clarify, but unless his alternative to gradualism looks a lot like a miracle, I don’t think he will be inclined to take it into consideration.
Nah, that’s not an issue at all, because Mung & Torley’s saltation theory involves stuff like invertebrates giving birth to vertebrates, so the newly created organisms would be unable to mate with their own kin, so the Designer would need to replicate the brick shitting event in enough unsuspected invertebrates to produce a large enough population of vertebrates that can keep micro-evolving on their own, while the Designer takes a well deserved rest for a job well done, until the next “eye-popping” macroevolutionary event
eye-popping, see what I did there? I’m on a roll
And in sexually-reproducing species that means sex. If the change in an individual is so large as to create a barrier to sex, it ain’t gonna happen. Hopeful monsters are lonely beasts.
(I think the point may have been made already, implicitly.)
In asexual species, such a change can also spread. In fact, maybe more easily as it cannot recombine with the previous genome.
I’ve often wondered why Darwinists do that.
Wrong again symbiosis-boy.
Imagine some critter that gobbles up some other critter, now we have two genomes where before there was only one, and they find a way to magically get along. POOF! An entirely new sort of creature.
Would that be “saltational” to you?
Mung,
You’re pathetic, Mung. Didn’t you have me on ignore anyway?
What do you think of symbiosis dazz? The BIG GULP. Never happens?
Mung,
derp
It seems to me Mung is in that wonderful position of not actually having made any pronouncements on how evolution (or the non-alternative) is supposed to proceed. Instead he just asks questions with a presumtuous rhetorical bend.
Why gradualism? Oh I suspect it’s because you’re afraid of magic/miracles.
That has basically been Mung’s output here. Like phoodoo, he never gets around to actually explaining why gradualism is a problem. And even less frequently than never do we hear him seriously propose an alternative.
Or a gene for how to be a salmon? Or an aardvark?
Rumraket thinks they are similar genes, with slight modifications. Or maybe convergent genes.
And because you can’t think of any alternatives. Your lack of imagination. That’s always a good argument.
Why do some evolutionists declare that gradualism is not only NOT required by evolutionary theory but is actually false? Have you stopped to think about that?
That was a stupid question Mung. You should know better.
I hear that salmon do converge in order to spawn.
But the last common ancestor to aardvarks and salmon had a mutation to its upstream swimming gene. All the ones that eventually became aardvarks kept swimming sideways and ended up in Africa.
Interestingly, it was a different mutation, one to the last common ancestor of the pterodactyl and the South American anteater which caused them to split. Pterodactyls had a gene which caused them to fly south for the winter. But then some got a mutation to that gene that caused them to get lost going home. They stayed in South America and became anteaters, exactly like the ones in Africa.
Only that is just coincedence…, er…I mean convergence.
If you are ever at an American zoo, in mid to late November, you will often see anteaters running and jumping then crashing into their cages spectacularly. This is them attempting to fly south.
Gradualism explained:
doofus -> doophus-> doophoo -> phoodoo
Note:
That is only South American anteaters that do that of course. African anteaters will do something that to the untrained eye looks similar. The way to tell the difference is that African anteaters will flap their tails more, like they are leaping up a waterfall, whilst the South American versions use an ungainly arm motion to try to propel themselves.
With proper breeding. And enough time. Heck, look at all the flying critters are out there. Making another one must be highly probable by now.
Saltation explained:
doofus -> mung
He knows that he’d become Robert Byers if he ever attempts to propose his alternative. Much like WJM without the courage of his convictions.
Mung,
I think that could legitimately fall under the banner, yes. Sex too, in my view, at least at its inception. But if you’re wondering ‘why gradualism?’, I’d guess you’d be talking of the general case. Gradualism does not preclude occasional leaps – gene transfer in particular is a mechanism without a particular size limit, though circumstantial, mechanistic difficulties are likely to make successful large ones comparatively rare.
I believe I dealt with this back here.
Thank you Allan.
Did you know that now you’re attacking evolutionary theory? You better be careful, people will think you’re an IDist. 🙂
Mung,
Every time an evolutionist mentions convergent evolution, I figure they have to be a closet IDist.
Or else mentally deranged.
phoodoo,
Do you think it contradicts the idea of the nested hierarchy?
Mung,
What, here or in my ‘evolution of sex’ thread? Or both? I doubt this is the first time anyone has ever challenged a mainstream view. Kind of how science works. [eta – although as far as endosymbiosis is concerned, I don’t think there’s any conflict. No one would regard it as ‘gradualist’.]
Not these days but it started out as a controversial idea. Could be there’s a slow-burning fuse on the evolution of sex! 🙂
Quick hint: not all character states are predicted to yield the same overall tree structure.
Every time an IDcreationist mentions convergent evolution, he puts his incompetence on display.
phoodoo,
What does it mean to be a closet IDist?
Is convergent evolution ‘explained’ by intelligent design? What is that explanation?
I’m interested to find out what ID supporters actually believe. Is convergent evolution a sign of design? Why? When things are not similar, is that also a sign of design? In other words, is only some biology designed?
I’m yEC but convergent evolutionism undercuts the whole presumption behind common descent trails(including historical classification systems)
Evolutionists on the mere data info of likeness in anatomy/genetics CONCLUDE this proves a common origin for later biological entities.
Nothing more sophisticated then that.
Then after beeter research has been done its discovered things atre alike which couldn’t be from common descent. SO they invoke/embrace convergent evolutiuonism to rescue their original hypothesis.
Its unwelcome to evolutionists to find “mutations” creating the same results in unrelated creatures.
its unlikely by common sense and the simple sense of the original grouping of traits for relationship.
Common design predicts like anatomy/genetics in unrelated creatures based on original blueprint concepts.
everybody gets mammary glands and hair because its a good idea from a creator with a blueprint.
Its not proof of common descent or any MAMMAL division in nature.
There are no mammals. Just kinds and drift from that.
Anyways likeness works for creationism and against evolutionist concepts.
Convergent evolution concepts is a retreating army.
it overthrows nested hierachery ideas with a thud.
How so, is convergent evolution just the designer reusing designs?
ETA: sorry O’M didn’t read your post first.
Teleology.
How much more obvious can it get.
That is a pretty abstract concept ,how does the designer create the teleological essence?
Rumraket,
When said IDist uses salmon/aardvark as an example of a convergent pair, I really sit up and take notice!
phoodoo,
I look forwards to you submitting this as an “explanation” for convergent evolution to an ID journal. Perhaps it’ll take people who you think are on your side laughing at you to make you realize the absurdity of your position.
In other news, are you sure you read that link I provided?
The psychological phenomenon of illusory superiority was identified as a form of cognitive bias in Kruger and Dunning’s 1999 study “Unskilled and Unaware of It: How Difficulties in Recognizing One’s Own Incompetence Lead to Inflated Self-Assessments”.[1] The identification derived from the cognitive bias evident in the criminal case of McArthur Wheeler, who robbed banks with his face covered with lemon juice, which he believed would make it invisible to the surveillance cameras. Wheeler’s incompetence was based on his misunderstanding the chemical properties of lemon juice as an invisible ink.
https://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect
As it seems to me that “teleology” as an “explanation” for convergent evolution is akin to lemon juice as a “disguise” for bank robbers. You just don’t realize how low quality your own claims are, but you seem to be doing a fine job thinking you are making insightful criticism of others positions.
You are the poster boy for the Dunning–Kruger effect.
It matters not, he could be asked by 1000 people and he’ll never say. Much like the 2k+ comments on “How are decisions made in phoodoo world” all he wants to talk about is evolution and how laughable it is, not his own claims.
Or, even more laughable, he thinks that “teleology” is actually an explanation.
It’s also obvious that the sun orbits the earth and that women are unclean while menstruating. And that bad smells cause disease. And that quantum tunnelling is a phenomenon where a particle tunnels through a barrier that it classically could not surmount. That’s obvious too.