Understanding through Discussion


Welcome! You are not logged in. [ Login ]
EvC Forum active members: 65 (9077 total)
71 online now:
AZPaul3, PaulK (2 members, 69 visitors)
Newest Member: Contrarian
Post Volume: Total: 894,038 Year: 5,150/6,534 Month: 570/794 Week: 61/135 Day: 1/6 Hour: 0/0


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   An ID hypothesis: Front-loaded Evolution
Dr Adequate
Member (Idle past 324 days)
Posts: 16112
Joined: 07-20-2006


Message 52 of 216 (653319)
02-20-2012 12:05 AM
Reply to: Message 1 by Genomicus
02-19-2012 5:43 AM


The front-loading hypothesis proposes that (a) early in earth’s history, the earth (or the solar system) was intentionally seeded with unicellular life forms (i.e., directed panspermia) and (b) these life forms contained the necessary genomic information to shape future evolution, such that the “course” of evolution was biased in pre-determined trajectories.

"Course" is singular, "trajectories" is plural.

This is not a mere grammatical quibble, I think there's a point that needs addressing here by you or by anyone else with a system of orthogenesis. If the course of evolution is preprogrammed into the first species, then how did its descendants evolve into a lobster and a giraffe? It can be preprogrammed to do one or the other, but how both? How do the same set of genetic instructions tell identical organisms: "Now, you evolve this way but you evolve that way"?

What are your thoughts on this?


This message is a reply to:
 Message 1 by Genomicus, posted 02-19-2012 5:43 AM Genomicus has seen this message

  
Dr Adequate
Member (Idle past 324 days)
Posts: 16112
Joined: 07-20-2006


Message 62 of 216 (653396)
02-20-2012 4:16 PM
Reply to: Message 53 by Genomicus
02-20-2012 12:08 AM


Re: The best of error minimizing codes?
As we learn more about the functions of the genetic code, it becomes ever clearer that the degeneracy in the genetic code is not exploited in such a way as to optimize one function, but rather to optimize a combination of several different functions simultaneously. Looking deeper into the structure of the code, we wonder what other remarkable properties it may bear. While our understanding of the genetic code has increased substantially over the last decades, it seems that exciting discoveries are waiting to be made.

Full optimization of one function may significantly reduce the optimization of another. Thus, a balance would have to be made between various functions.

So it might be optimal ... based on criteria that we haven't discovered yet?

Well yes, and the aliens might descend in their spaceship and say: "Yeah, you got us, we bukkaked your planet with directed panspermia". But maybe we should confine ourselves to the evidence we have now rather than evidence we might discover in the future.

The genetic code is, nevertheless, at a local optimum for error minimization. And the absence of a phylogenetic tree like I describe in my essay, and the fact that this highly optimized genetic code is nearly universal, points to front-loading.

Given that local optimization is exactly what evolution does, no it doesn't, particularly.

The prokaryote LUCA could easily have had a thoroughly sub-optimal genetic code.

Could have, perhaps. But unless you can say would have, which you can't, that's not much of a point.

According to your own scheme the LUCA could also have had a thoroughly sub-optimal genetic code, programmed to get better and better in its descendants as time progressed. Why not? So apparently even being able to look at LUCA would not distinguish between the two hypotheses. Perhaps you should think of something that would.


This message is a reply to:
 Message 53 by Genomicus, posted 02-20-2012 12:08 AM Genomicus has seen this message

  
Dr Adequate
Member (Idle past 324 days)
Posts: 16112
Joined: 07-20-2006


Message 67 of 216 (653469)
02-21-2012 2:15 PM


Some Objections
Infinite Regress

One usual case made against front-loading is that while a gene was waiting to become useful, it would be turned into nonsense by genetic drift. I note with pleasure that you have proposed that these genes would be doing something else useful until they were converted to different genes by some pre-programmed process.

But then what about the genes that pre-program the process? To take a concrete instance, the genes that say what genetic changes must be made to turn a land animal into a whale.

Now, these genes themselves must have been doing something else all the time before whales evolved; for two reasons. First, if they'd been saying all along: "Now evolve into whales" then we'd have got whales much sooner. Second, because if they hadn't been doing something, then they themselves would have been turned into nonsense by genetic drift.

But then we need a third set of genes to tell these genes to turn into genes telling other genes to turn into whale genes. And these genes must have had a function other than that, for the same reason that the turn-into-whale genes must have had another function.

Which means that there must have been a fourth set of genes affecting the third set of genes ...

And so on and so forth.

Timing

And then there's the question of timing. How do the genes know: "OK, now it's whale time!" Whatever the genes were for making whales evolve, they were, by your hypothesis, always present from LUCA on down. How do they know when to spring into action? Must there not have been a causal factor external to the genome, causing changes in the genome, to make it start producing whales?

Branching

You haven't answered my question about this, so let me ask it again. According to your hypothesis, LUCA must have had genes to turn it into a whale, and a spider, and an oak tree, and a camel. So what decides which it will actually do?

Ultra-Lamarckism

The only way out that I can see for you is a sort of ultra-Lamarckism. The genes should be able to look around themselves and say: "Hey, I'm in a desert. Better turn into a camel!"; or "Hey, the dinosaurs have gone extinct. It's time for adaptive radiation of mammals!" or "OK, lobsters have been done, so I'd better turn into a tree instead" and change accordingly.

But we have no evidence that genes can respond to environmental feedback in this way. Indeed, where would be the feedback? How could the prospective ancestor of trees know about the existence of lobsters?

Meanwhile we do have known mechanisms that explain ordinary Darwinian evolution.

Edited by Dr Adequate, : No reason given.


Replies to this message:
 Message 68 by PaulK, posted 02-21-2012 2:47 PM Dr Adequate has taken no action

  
Dr Adequate
Member (Idle past 324 days)
Posts: 16112
Joined: 07-20-2006


(1)
Message 77 of 216 (653493)
02-21-2012 5:50 PM
Reply to: Message 75 by Genomicus
02-21-2012 5:38 PM


Re: Into the swamps...
As Bluejay predicted, I am effectively getting swamped with responses. So is there anyone who would especially like me to respond to their points?

Well, speaking for myself, I would especially like you to respond to my points.

But it doesn't really matter. So long as eventually you get round to explaining your ideas by and by, that's fine. So long as you keep on trying to get round to this or that explanation of your idea, no-one really cares if you'll produce the explanation right now, right away, or later. Do it in your own time.

We evolutionists may be a bit mean in some ways (I know I am) but I think we'll all give you as much time as you like to think of your own hypothesis.


This message is a reply to:
 Message 75 by Genomicus, posted 02-21-2012 5:38 PM Genomicus has taken no action

  
Dr Adequate
Member (Idle past 324 days)
Posts: 16112
Joined: 07-20-2006


Message 85 of 216 (653536)
02-22-2012 11:21 AM
Reply to: Message 82 by Genomicus
02-22-2012 5:03 AM


Re: The best of error minimizing codes?
I have read the paper you cited earlier. Their conclusions are in direct contradiction with the conclusions of Freeland et al.

Wait ... scientists are disagreeing about something? This has hardly ever happened before.

Seriously, you wish to turn biology on its head and show that our most fundamental ideas about it are wrong. I admire your ambition. But you cannot achieve this with reference to evidence that is itself speculative and unproven. According to your hypothesis (if you fudge it a bit) it would be jolly nice if the genetic code was globally optimal. But no-one has proved this to be the case. The fact that some people have speculated that this is the case is not a reason to throw over Darwinism and start believing in front-loaded evolution instead.


This message is a reply to:
 Message 82 by Genomicus, posted 02-22-2012 5:03 AM Genomicus has replied

Replies to this message:
 Message 109 by Genomicus, posted 02-23-2012 11:08 PM Dr Adequate has replied

  
Dr Adequate
Member (Idle past 324 days)
Posts: 16112
Joined: 07-20-2006


Message 116 of 216 (653738)
02-24-2012 12:58 AM
Reply to: Message 107 by Genomicus
02-23-2012 10:27 PM


Re: General Response to Objections
If Dr Adequate’s objection is indeed valid, then we must believe that this hypothetical plant population could not front-load the appearance of both C4 photosynthesis and hemoglobin (I am, of course, supposing that there’d be a selective advantage to both of these biological features). If I understand his objection correctly, he’s suggesting that only one of these features could be front-loaded.

No, no, you misunderstand me. Let's hypothesize that they're both front-loaded. Fine. But at some point branching has to take place. One lineage has to go one way and do photosynthesis, while the other goes the other way and does hemoglobin. Now this itself, on the face of it, cannot be preprogrammed. The reason why one lineage develops one way and another develops in another way cannot be the result of their common genetic heritage.

So what, in your scheme, does explain it?


This message is a reply to:
 Message 107 by Genomicus, posted 02-23-2012 10:27 PM Genomicus has replied

Replies to this message:
 Message 119 by Genomicus, posted 02-24-2012 3:46 AM Dr Adequate has replied

  
Dr Adequate
Member (Idle past 324 days)
Posts: 16112
Joined: 07-20-2006


Message 117 of 216 (653739)
02-24-2012 2:17 AM
Reply to: Message 107 by Genomicus
02-23-2012 10:27 PM


Re: General Response to Objections
I’d like to point out that the argument “I can’t imagine how the eye could have been front-loaded, therefore it could not have been” isn’t really all that valid.

Actually, I think it is.

Now, it is perfectly true that if someone claims that such-and-such a thing occurs, or has occurred, then it is not a conclusive argument against this claim to point out that they have no theory explaining how it occurred. To take a trivial example, I've seen Penn and Teller do their bullet-catching trick. I have no idea how they did it. I'm still certain that I've seen them do it.

But this is not like the situation that we are in. We agree on what happened: life evolved by radiation from a common ancestor. What you are trying to do is produce a theory explaining that fact. So it is actually a valid criticism of your theory to point out that it does not in fact explain the things that it's meant to explain. That's the whole point of a theory, that's what theories are meant to do. They're meant to explain the facts. If it doesn't do that, it's no good.


This message is a reply to:
 Message 107 by Genomicus, posted 02-23-2012 10:27 PM Genomicus has replied

Replies to this message:
 Message 120 by Genomicus, posted 02-24-2012 3:56 AM Dr Adequate has replied

  
Dr Adequate
Member (Idle past 324 days)
Posts: 16112
Joined: 07-20-2006


Message 124 of 216 (653752)
02-24-2012 4:24 AM
Reply to: Message 119 by Genomicus
02-24-2012 3:46 AM


Re: General Response to Objections
Alternatively, the front-loading designers could have designed such a population from the start: where some cells have genes for plants, and others have genes for animals.

Well, this would be a bit of a climb-down. Are you going to give up on common ancestry?

Yes, but front-loading isn't about pre-programming something. It's about "stacking the deck," and anticipating the rise of plants and animals, for example. Simply put, if we start with an origin population of cells, which contain genes necessary for the development/function of plants and animals; next, this initial population separates into two populations. Then, deletion events in one population removes the animal genes, say, so that we just end up with plants.

But you're still not drawing a picture.

This "deletion event" happens to plants, but not animals. When they start off with the same genome. What causes this to happen?

If you want to stick with common ancestry, then there must be some causal factor other than the genome that makes the "deletion event" occur.

Well, what is it?

If you do wish to abandon common ancestry then we have a whole 'nother discussion on our hands.


This message is a reply to:
 Message 119 by Genomicus, posted 02-24-2012 3:46 AM Genomicus has replied

Replies to this message:
 Message 130 by Dr Jack, posted 02-24-2012 4:52 AM Dr Adequate has replied
 Message 132 by Genomicus, posted 02-24-2012 5:02 AM Dr Adequate has replied

  
Dr Adequate
Member (Idle past 324 days)
Posts: 16112
Joined: 07-20-2006


Message 127 of 216 (653755)
02-24-2012 4:39 AM
Reply to: Message 120 by Genomicus
02-24-2012 3:56 AM


Re: General Response to Objections
Well, not when seen in the context of other biological features. In my little essay, I showed how (a) it is feasible for specific proteins to be front-loaded; (b) it is feasible for specific molecular machines to be front-loaded; and (c) how specific biochemical pathways can plausibly front-loaded. Thus, demanding that I explain the origin of the eye through FLE seems to be pushing the goal-posts back. The FLE hypothesis is just in its infancy; demanding that we produce a teleological hypothesis for the origin of the eye, at this point, seems a little premature, to me at least.

Well, you know, if you want to develop the hypothesis, and you find you need another few years to get it right, then you go for it. As I said, I do admire your ambition. You're almost certainly wrong, but science would not progress unless people pursued seemingly crazy ideas. I've pursued a few of those myself.

But, you can't expect anyone to accept your ideas when they're in their present half-formed condition. All I can do is wish you the very best of luck. But if you can't explain the evolution of the eye, then presently we have to say that your hypothesis has failed to do what it is meant to do, namely explain evolution.


This message is a reply to:
 Message 120 by Genomicus, posted 02-24-2012 3:56 AM Genomicus has replied

Replies to this message:
 Message 134 by Genomicus, posted 02-24-2012 5:09 AM Dr Adequate has taken no action

  
Dr Adequate
Member (Idle past 324 days)
Posts: 16112
Joined: 07-20-2006


Message 135 of 216 (653766)
02-24-2012 5:12 AM
Reply to: Message 130 by Dr Jack
02-24-2012 4:52 AM


Re: General Response to Objections
I don't see that this necessarily holds. Gene deletion happens, neither we nor Genomicus are going to dispute that, right? You don't need a special causal factor to account for the deletion.

I didn't say that the causal factor needed to be "special". I just said that there has to be one. Two lineages evolve in different directions. This cannot be solely caused by the same gene passed down from the same common ancestor, or they'd both evolve in the same direction. There must be another causal factor.


This message is a reply to:
 Message 130 by Dr Jack, posted 02-24-2012 4:52 AM Dr Jack has replied

Replies to this message:
 Message 137 by Dr Jack, posted 02-24-2012 5:15 AM Dr Adequate has replied

  
Dr Adequate
Member (Idle past 324 days)
Posts: 16112
Joined: 07-20-2006


Message 139 of 216 (653770)
02-24-2012 5:17 AM
Reply to: Message 132 by Genomicus
02-24-2012 5:02 AM


Re: General Response to Objections
How on earth would this be incompatible in any way with common ancestry? You'd simply design cell population A with genes that would be later used by plants, and cell population B with genes that would be later used by animals. These two populations, on the whole, would be genetically related, with the exception of the different plant/animal genes.

Well no they wouldn't, 'cos of not having a common ancestor. They might be genetically similar, but they couldn't be genetically related.

Not meaning to dodge this question, but I think Mr Jack has answered this question succinctly.

He may have been succinct, but he was also wrong.

Something has to make the difference. This something, by your hypothesis, cannot lie in the genome. Where, then, does it lie?


This message is a reply to:
 Message 132 by Genomicus, posted 02-24-2012 5:02 AM Genomicus has replied

Replies to this message:
 Message 142 by Genomicus, posted 02-24-2012 5:24 AM Dr Adequate has replied

  
Dr Adequate
Member (Idle past 324 days)
Posts: 16112
Joined: 07-20-2006


(1)
Message 141 of 216 (653772)
02-24-2012 5:22 AM
Reply to: Message 137 by Dr Jack
02-24-2012 5:15 AM


Re: General Response to Objections
I don't see why you feel chance is an insufficient factor?

I didn't say it wasn't. But if that's what Genomicus thinks, then he should say so. What I am trying to elicit from him is what he thinks this factor is. It cannot be the genome. It must be something else. I want to hear from him what he thinks it is. If he says "chance" then we can continue the discussion on that basis.


This message is a reply to:
 Message 137 by Dr Jack, posted 02-24-2012 5:15 AM Dr Jack has seen this message

  
Dr Adequate
Member (Idle past 324 days)
Posts: 16112
Joined: 07-20-2006


Message 143 of 216 (653774)
02-24-2012 5:30 AM
Reply to: Message 142 by Genomicus
02-24-2012 5:24 AM


Re: General Response to Objections
Chance.

OK, that's a new factor in your hypothesis. Chance decides it.

But in that case, shouldn't we stop calling your hypothesis front-loaded evolution, when it is, according to you, just how the dice happened to fall? What I understood by "front-loaded evolution" is that the outcome was inevitable. If, instead, it is random, then perhaps you should think of another name for it.


This message is a reply to:
 Message 142 by Genomicus, posted 02-24-2012 5:24 AM Genomicus has replied

Replies to this message:
 Message 145 by Genomicus, posted 02-24-2012 5:40 AM Dr Adequate has replied

  
Dr Adequate
Member (Idle past 324 days)
Posts: 16112
Joined: 07-20-2006


(2)
Message 148 of 216 (653780)
02-24-2012 5:58 AM
Reply to: Message 145 by Genomicus
02-24-2012 5:40 AM


The Role Of Chance
Chance has always been a factor in the FLE hypothesis.

Then you would have done well to mention this in your OP instead of waiting 'til now.

But if chance is a factor, then in what sense is evolution front-loaded? If it is purely a matter of chance that evolution produced humans and tigers rather than bumblegriffs and hippodores, then where is the front-loading?

If you wish to advocate for directed panspermia, then let's continue the discussion on these lines. But I don't see how you can argue for front-loaded evolution and also ascribe a highly significant role to mere chance.


This message is a reply to:
 Message 145 by Genomicus, posted 02-24-2012 5:40 AM Genomicus has replied

Replies to this message:
 Message 150 by Genomicus, posted 02-24-2012 6:05 AM Dr Adequate has replied

  
Dr Adequate
Member (Idle past 324 days)
Posts: 16112
Joined: 07-20-2006


Message 152 of 216 (653785)
02-24-2012 6:10 AM
Reply to: Message 109 by Genomicus
02-23-2012 11:08 PM


Re: The best of error minimizing codes?
Actually, it happens all the time. Investigators do disagree on the origin of the type III secretion system, for example (i.e., there is a good bit of disagreement on whether the TTSS and the bacterial flagellum are sister groups or whether the TTSS descended directly from the flagellum).

Ah, I missed this until Percy replied to it.

I was being really really sarcastic. Really, really, really sarcastic.

My point remains. You want to turn all biology on its head. Again, I admire your ambition and wish you luck. But you can't do that with reference to evidence that people don't actually agree is evidence and that many scientists think is untrue. Maybe one day someone will prove that it's true. But until then you can't back up a speculative hypothesis with equally speculative evidence, 'cos that doesn't work.

Not meaning to quibble over semantics here, but science isn't so much about proving things as it is about providing evidence.

Using the phrase: "Not meaning to quibble over semantics" does not in fact stop you from quibbling about semantics when that is in fact exactly what you're doing. When I am king, that phrase will be banned along with all sentences beginning with the words: "No offense, but ..." and "I'm not a racist, but ..."

Being king is awesome.


This message is a reply to:
 Message 109 by Genomicus, posted 02-23-2012 11:08 PM Genomicus has taken no action

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2018 by EvC Forum, All Rights Reserved

™ Version 4.1
Innovative software from Qwixotic © 2022