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Author Topic:   An ID hypothesis: Front-loaded Evolution
Blue Jay
Member (Idle past 1487 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 49 of 216 (653303)
02-19-2012 9:30 PM
Reply to: Message 1 by Genomicus
02-19-2012 5:43 AM


Hi, Genomicus.

Welcome to EvC!

It's nice to see an IDist who's taken some time and put some good thought and reasoning into his work.

For my post, I want to focus on this bit:

Genomicus writes:

The front-loading hypothesis proposes that ... [the intentionally seeded] life forms contained the necessary genomic information to shape future evolution, such that the “course” of evolution was biased in pre-determined trajectories.

Since front-loading predicts biases in the trajectory of evolution, shouldn't we be able to detect these biases by examining patterns in evolutionary trajectories across multiple lineages? For example, if the front-loaders intended to promote the emergence of a certain characteristic, wouldn't we predict that multiple lineages of descendant organisms would evolve that characteristic? Isn't this what "biased evolutionary trajectories" means?

Based on this, wouldn't it be reasonable to argue that characteristics that only emerged once in Earth's evolutionary history probably were not front-loaded into the original propagule? Any technique that biases evolution toward a certain trajectory, yet only results in one out of millions of lineages following that trajectory, was either a very ineffective technique, or an astonishingly complex algorithm that surely even you don't believe was encoded into a single prokaryotic propagule.

Edited by Bluejay, : A redundant redundancy


-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.


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

Replies to this message:
 Message 50 by Jon, posted 02-19-2012 10:04 PM Blue Jay has responded
 Message 56 by Genomicus, posted 02-20-2012 5:49 AM Blue Jay has responded

  
Blue Jay
Member (Idle past 1487 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 51 of 216 (653317)
02-19-2012 11:46 PM
Reply to: Message 50 by Jon
02-19-2012 10:04 PM


Hi, Jon.

Jon writes:

Legs. Wings. Eyes.

So... the first animal was front-loaded?

What about the first prokaryotic progenitor of all life? Why did only one sub-sub-lineage of its descendants manifest these front-loaded characteristics?

Edited by Bluejay, : Rewording


-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.


This message is a reply to:
 Message 50 by Jon, posted 02-19-2012 10:04 PM Jon has responded

Replies to this message:
 Message 58 by Jon, posted 02-20-2012 10:14 AM Blue Jay has acknowledged this reply

  
Blue Jay
Member (Idle past 1487 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 54 of 216 (653324)
02-20-2012 1:04 AM
Reply to: Message 53 by Genomicus
02-20-2012 12:08 AM


Re: The best of error minimizing codes?
Hi, Genomicus.

Genomicus writes:

I don't mind objective criticism at all, but for the record, for all of you: now that the weekend is over, I won't have that much time to respond to all of you - only one or two responses per day, unless I can muster some more time. This means that I will be only responding to the highest-quality criticisms...

No sweat: IDists frequently get swamped here. Nobody will mind if you take a long time to write a high-quality response.

Just so you know, if you start to get too far behind, I intend to yield the floor to others. That will help focus the debate better. And, I consider Mr Jack and Bluegenes superior debaters and superior representatives for the positions I would argue, anyway.

Any threads of discussion you choose not to follow (including mine) can always be revisited some other time.


-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.


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

  
Blue Jay
Member (Idle past 1487 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 60 of 216 (653386)
02-20-2012 3:08 PM
Reply to: Message 56 by Genomicus
02-20-2012 5:49 AM


Hi, Genomicus.

Thanks for the reply.

Genomicus writes:

In the first place, I'm not envisioning anything like extreme front-loading, where something as specific as the human species is front-loaded.

Thanks for the clarification: though, I already figured you for someone wouldn't make this argument.

Genomicus writes:

So if I'm understanding you correctly, you're saying that if multicellularity was front-loaded, we should expect multicellular life forms to evolve independently. But this is what is believed to have occurred; that is, that multicellular life forms arose multiple times but many of these lineages went extinct...

Well, I wasn't trying to put forward an example yet: I was trying to establish a conceptual principle whereby we could test the predictions of FLE.

And, yes, there are indeed many lineages of multicellular organisms. As the article you cited mentioned, there are probably at least 5 independent emergences of "true" multicellularity. And, depending on how we define "multicellularity," there are also prokaryotes that can count as multicellular (some cyanobacteria, for instance).

So, based only the single criterion I proposed, I would regard multicellularity as potentially consistent with the front-loaded evolution hypothesis.

Genomicus writes:

And there is good evidence of biased trajectories of important biological features: to name just one example, eyes have evolved independently in different lineages - indicative of a biased trajectory.

My concern with the specific example here (eyes) is that the bias in trajectory only emerges in one "later branch" of the Tree of Life (Metazoa). So, it seems that the capacity to develop eyes isn't rooted at the base of the Tree of Life, but at the base of the animal branch of the Tree of Life.

Unless FLE allows for front-loading within individual branches of the tree, and not exclusively at the base of the tree, I think the proper conclusion is that eyes probably were not front-loaded.

Genomicus writes:

Essentially, it would not be reasonable to argue that "characteristics that only emerged once in Earth's evolutionary history probably were not front-loaded into the original," because lineages can be lost through deep time.

Please observe the parallels between your argument here and a specific statement you made in the OP:

Genomicus writes:

Arguing that the sub-optimal codes once did exist early in life’s history, but vanished once the optimal codes came on the scene (i.e., that they were outcompeted), looks awfully ad hoc.

I will accept your "deep-time" argument if you withdraw your objections to the similar argument in relation to sub-optimal genetic codes.

Edited by Bluejay, : No reason given.

Edited by Bluejay, : No reason given.

Edited by Bluejay, : last time: I swear


-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.


This message is a reply to:
 Message 56 by Genomicus, posted 02-20-2012 5:49 AM Genomicus has responded

Replies to this message:
 Message 64 by Genomicus, posted 02-20-2012 10:24 PM Blue Jay has responded

  
Blue Jay
Member (Idle past 1487 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 81 of 216 (653515)
02-22-2012 12:09 AM
Reply to: Message 64 by Genomicus
02-20-2012 10:24 PM


Hi, Genomicus.

Like everybody else, I don't think there's any rush to respond to me. I'll still be here whenever you get around to responding.

Genomicus writes:

Do note, too, that the more specific the front-loading objective, the less likely it is that that objective will evolve multiple times.

The more specific the objective, the less likely the objective is to be met at all using a crude technique like front-loading. I find it highly dubious to suggest that something as specific as an eye could feasibly be front-loaded at all for this exact reason.

Unfortunately, I think this is going to leave you in a conundrum: only the most basic, fundamental characteristics that have broad utility for a wide diversity of organisms could be front-loaded. But, the prevalence of those characteristics is expected under anybody's model of the origin and history of life. So front-loading without specific objectives would make no unique predictions, and would thus be untestable.

Genomicus writes:

Well, you wouldn't expect eyes in prokaryotes, now would you?

Why not? Otherwise, you've got a gene that has to persist for a very long time with minimal change due to mutation, while not fulfilling its eye-related functions. If you suggest that it could fill another function in the interim, you'd have to accept that it would be undergoing selection for that other function, which leaves no guarantee that it would still be serviceable in eye development once an organism capable of using it to develop eyes evolved.

Surely we have to accept that front-loaded eyes are a dubious proposition.

Genomicus writes:

Actually, the capacity for eye development is encoded at the root of the phylogenetic tree of life.

But only the animals seem able to actually evolve eyes, because they evolved them several times, and no other group did. Doesn't this suggest that the capacity doesn't exist at the base of the tree?


-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.


This message is a reply to:
 Message 64 by Genomicus, posted 02-20-2012 10:24 PM Genomicus has not yet responded

  
Blue Jay
Member (Idle past 1487 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 184 of 216 (654186)
02-27-2012 4:33 PM
Reply to: Message 183 by Trixie
02-27-2012 4:23 PM


Re: General Response to Objections
Hi, Trixie.

Trixie writes:

If homology is structural only, it suggests that the same solution has been hit on by different organisms independently of each other.

Can there even be such a thing as a "structural homolog"?


-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.


This message is a reply to:
 Message 183 by Trixie, posted 02-27-2012 4:23 PM Trixie has responded

Replies to this message:
 Message 185 by Trixie, posted 02-27-2012 4:50 PM Blue Jay has not yet responded

  
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