|
Author
|
Topic: Front Loading: A Research Program (based on the ideas of Christian Schwabe)
|
John Bracht
Member
Member # 5
|
posted 28. April 2002 20:45
I've been reading articles lately by the biochemist Christian Schwabe of the Medical University of South Carolina. His ideas are highly controversial, as he denies neoDarwinism as the source of biological complexity and believes that life has originated as an inevitable product of primordial conditions. He does not agree with intelligent design, and I would classify his ideas as being a form of self-organization. I find his ideas be be fascinating and truly novel; I also see several possible tie-ins with intelligent design theory (especially a front-loading hypothesis), from his critique of neoDarwinism to his proposal for a future research program to verify his theory. First, I'll give a quick overview of Schwabe's ideas:
1. He views life as polyphyletic; multiple single-cellular lineages arose independently on the early earth. The (nearly) universal genetic code is proof that there is a tendency in the physio-chemical laws (which has yet to be characterized) for only one code to arise consistently. The linking of nucleotides into genes gave rise to many redundant genes in different organisms, hence the prevalence of gene families and similar genes across species. (In other words, similarity is the result of redundancy and a tendency for laws to direct the process in that direction).
2. Each of these single-cellular organisms underwent a period of approximately 3 billion years in which it was undergoing genetic reshuffling and building genomic complexity. This process was driven by thermodynamical properties of DNA, RNA, and proteins--not by the neoDarwinian process.
3. After this developmental period (which was mostly not recorded in the fossil record due to the small size of the organisms) and after enough genomic complexity had build up, each lineage independently blossomed into multicellularity. Once that transition to multicellularity occurred, the species were stable and did not evolve (hence the sudden origin and then stasis observed in the fossil record). Thus, the Cambrian explosion records the first of these organisms. The implication is that for each multicellular species in the fossil record, there was a single-cellular predecessor all the way back to the origin(s) of life in the primordial conditions.
For more reading, see
http://www2.prestel.co.uk/littleton/schwabe.htm
http://www.eurekah.com/categories.php?catid=27 (includes fairly detailed chapter summaries of a book he's published)
Schwabe C. On the Validity of Molecular Evolution. TIBS. July 1986;11:280-3.
Schwabe, C., Warr, G. W., "A polyphyletic View of Evolution: The Genetic Potential Hypothesis." Perspectives in Biology and Medicine, 27, 3, Spring 1984 pg. 465-484.
Because he believes that the entire potential for multicellularity was present in the earliest life forms, he calls his theory the genetic potential hypothesis.
One idea that Schwabe proposes is that the neoDarwinian mechanism doesn't create new information. All the information was generated at the origin of life; it's just been shuffled and re-expressed in new ways over time until multicellularity is produced. This is remarkably similar to Dembski's ideas about the conservation of information, in which no new information (CSI) is generated by natural causes (law, chance, or a combination like neoDarwinism).
One obvious weakness of Schwabe's model is the fact that it has no mechanism for creating all this new information at the beginning. He hopes that an as-yet undiscovered law will be found, but I think a stronger argument is to posit the very thing that has been shown to be able to create new information: intelligence. Thus, his model fits very well with the idea of "front loading" where a designer would create the first cell lineages with the express capacity to develop into multicellular organisms.
Interestingly, Schwabe proposes a research program (from "On the Validity of Molecular Evolution," cited above):
quote:
The [neoDarwinian] paradigm suggests that life evolved from singularity and simplicity to multiplicity and complexity. If indeed aquisition of complexity via gene duplicationas and mutations occurs continuously then early organisms should not contain advanced function genes but rather only the few catalysts and genes required for primitive forms of life. If certain molecules were, however, found in both Mammalia and Arthropoda for example, then it would be reasonable to assume that the corresponding gene had already existed before Mammalian and Arthropoda separated, that is at the age of the Cnidaria. If plants and animals share homologous proteins then the parent gene must date back to the branching point of the kindgdoms. Finally, if microorganisms contain a protein similar to the one occurring in mammals, then that gene had to be as old as the prokaryotes, that is as old as life itself.
Provided that one could show that advanced function molecules do indeed occur in species that lived at the earliest putative branching point (regardless of function) then one has demonstrated that gene duplications and mutations would have been unnecessary to produce these advanced functions. Furthermore, one would have obtained evidence to suggest that these genes probably had a very early or even primordial origin.
One such "advanced function molecule" is Relaxin, which is used in mammals to widen the birth canal during the birthing process. Yet it is also found in prokaryotes, plants, and unicellular eukaryotes.
Other advanced function molecules include insulin (present in bacteria, protozoa, vertebrates, and insects), Thy-1 neuronal glycoprotein (in squid and mammals), beta-2 microglobulin (in cnidaria, mollusks, arthropods, vertebrates), and histocompatability antigens (in insects and vertebrates). Schwabe gives more instances: "For example, insulins, relaxins, adrenocorticotropic hormone, and somatostatin, have been identified in the prtista." (from: A Polyphyletic View of Evolution: the Genetic Potential Hypothesis)
The implication is that these proteins were present far earlier than we would expect based on an evolutionary history. The natural question is: precisely how early did these proteins arise? Were they present in the universal common ancestor? If so, the implications are very problematic for any neoDarwinian account of these proteins, for the simple reason that there was no time for an evolutionary scenario to have produced them. Somehow, they must have arisen without gene duplication, cooptation, random walks across sequence space, etc. [On a side note, it would appear that certain irreducibly complex protein complexes are fundamental to all known life forms and must have been present in the universal ancestor; the f1/f0 ATP-ase is an excellent example.]
The obvious objection by the neoDarwinist is that these advanced function molecules aquired their advanced function by cooptation from a more primitive function. But their explanation runs into some problems. It particular, it often happens that the advanced function is tied to an irreducibly complex system. In such a case, multiple protiens must be coopted at precisely the same time and fall together into the correct configuration to give rise to the new function. Schwabe makes some relevant comments on the improbabilities of such a scenario:
quote:
To develop an endocrine system of the complexity and specificity as observed in contemporary animals by a chance-oriented mechanism is not an option. The probability of simultaneous coordinated mutations that lead to the production of a messenger in one part of the body and to the production of the receptors with the appropiate tissue response and distribution in another part, is unqualified nonsense.
[from: http://www.eurekah.com/categories.php?catid=27, click on "Thoughts on Multi-Cellularity: How Nature got Around Darwin"]
In other words, he points to the irreducible complexity of the system (signal, receptor, response system) as making the Darwinian pathway (which includes cooptation as a chance-oriented mechanism) simply untenable.
Schwabe sees cooptation as a natural (non-Darwinian) process of reorganizing and realizing the genomic potential inherent within organisms. If we couple his ideas with front-loading, this suggests that cooptation may be a sign of engineering design. It makes sense that an extremely clever engineer would design various parts to be able to function in very different systems as the entire organism develops with time. Perhaps relaxin played some role in earliest prokaryotes and was intelligently pre-adapted to its vital role in enlarging the birth canal once multicellularity was reached. This would be a reasonable way to get around the prohibitive improbabilities of the chance-driven cooptation scenario.
Furthermore, it makes a lot of sense from a front-loading point of view that an organism might have been pre-equipped with all the proteins it is going to need when it becomes multicellular, and when the time comes they just fall together in a way that appears, to us, to be nothing short of miraculous. Some implications of this (and Mike Gene has explored some ideas like this) are that we might be able to find single-celled life forms that have proteins that are "preadapted" to functions they do not yet fulfill. Relaxin might be one such protein; Mike has talked about histone proteins (in archaea, I think) as another possibility (though I don't know any of the details on this).
In short, it seems that Christian Schwabe's ideas, coupled with a front-loading hypothesis, suggest that we should expect and look for advanced function molecules that are out of place or present in very simple, "primitive" organisms. Furthermore, cooptation might be a key sign of intelligent design, not of neoDarwinian evolution.
John Bracht
[ 28 April 2002, 20:56: Message edited by: John Bracht ]
IP: Logged
|
|
Mike Gene
Member
Member # 149
|
posted 28. April 2002 23:14
Great stuff, John. I recall reading Schwabe's TIBs article many years ago, but I didn't realize that I was independently converging on his ideas. It will be truly exciting to read his stuff, as it is difficult to develop such ideas all on your own.
As for front-loading, I've been speculating along these lines for almost two years now. Here is one example from a debate I has about this issue:
Let's think about globin from a perspective of front-loading. Here's the design problem - how do you indirectly design a mammal-like organism by directly designing single-celled life forms? Because of their size and metabolism, mammal-like organisms are going to require plenty of oxygen to drive the electron-transport chain (something you designed and expect to be passed on due to passive-frontloading). So part of the design problem is providing a means of delivering this oxygen. Because of your extensive understanding of protein biochemistry, you have found/designed something like globin, a spectacular protein that serves this purpose almost perfectly. So you endow some of your original life forms with globin. Now you face another design problem. Unless globin serves your original microbes, it is a functionless pseudogene and will decay away quickly. How do you preserve the globin for hundreds of millions of years so that it is present when the biosphere is ready to evolve mammal-like organisms? Well, there are three possible ways of doing this:
(a). Give globin a function in microorganisms.
(b). Employ a protein very similar to globin in microorganisms (meaning it would be easy to evolve globin eventually).
(c). Both (which increase the odds of globin being present when called for).
First, hemoglobin (Hb) occurs in all the kingdoms of living organisms, even though its distribution is episodic among the nonvertebrate groups in contrast to vertebrates. In bacteria, it is used for O2 sensing and to control NO levels. Also, in some cyanobacteria, it is used to increase the efficiency of oxygenic photosynthesis. Yet the episodic distribution among microorganisms indicates that Hb is not essential for microbial life, like it is for vertebrate life. This, BTW, helps us to understand why the mechanisms of lateral gene transfer were designed.
Secondly, globins and certain cytochromes have similar structures. Both bind heme groups, where the former binds oxygen and the latter binds electrons. If the designed globins were lost, they could be regenerated through the cytochromes.
The bottom line is that if a designer introduced cytochromes/globins into their original cells, they would not be surprised at all to find that a mammal-like creature, evolving billions of years later, also "just happened" to have built their circulatory systems around it. No, that may very well what their models would have predicted.
There is an even more interesting twist on the whole story. Let's face it - we really have a very rudimentary understanding of evolutionary processes. Instances of common descent may be firmly established, but when we turn to mechanisms, we are still strongly dependent on very vague just-so stories. Now, I happen to think that as we understand development and cell biology better and better, we will begin to realize that evolution has been a very sophisticated process. Consider the mammalian circulatory system. Its "business end" is gas exchange. And there are three components to such gas exchange - flow of blood to the tissue, release of oxygen from the blood, and use of oxygen by the tissue cells. What is really cool is that each one of these three basic steps is built around the heme-binding domain - NO release (now known to more sophisticated that previously thought) to regulate blood flow through altering tonicity of the vessel walls; O2 release and CO2 capture in RBCs; and the electron transport chain in tissue cells. Molecular properties, that can be designed, may serve to "guide" organismal evolution more than appreciated such that in this case, the properties of designed proteins in bacteria rigged things such that this 3-component gas exchange would eventually emerge mammal-like critters and function as it does.
And here's the histone stuff I wrote earlier:
Front-Loading Evolution
We've already seen an example whereby an initial design event expresses itself throughout its subsequent history, but there is another more tantalizing example on the horizon. In this case, we may have an example whereby something is designed only so that it's design potential is not realized until much later in evolution. The paper I have in mind is:
Ausio, J. 2000. Are linker histones (histone H1) dispensible for survival? BioEssays 22: 873-877.
In this paper, Ausio covers a lot of evidence whereby histone H1, which functions to link nucleosomes and thus more efficiently package DNA in eukaryotes, is not essential for survival and reproduction in filamentous fungi. If we eliminate H1 function in Ascolobus and Aspergillus, the cells are perfectly viable with no deleterious consequence on the sexual reproduction cycle. The same results were previously seen in the protozoan Tetrahymena. However, in the fungi mentioned, elimination of H1 does result in the cessation of growth within a week or two. In other words, elimination of H1 does not affect viability or reproduction, but only the life-span of the individual organism (however, with Aspergillus, elimination of H1 does not even effect the life span of the organism and has no apparent effect).
Three more points. First, thus far H1 is ubiquitous in eukaryotes. Secondly, H1 may not be crucial in single-celled organisms; in addition to the Tetrahymena data, Ausio observes, "These results suggest that while linker histones may be dispensable for the relatively short life span of an individual cell, they are most likely indispensable for survival of higher eukaryote organisms." Thirdly, Ausio argues that this is probably not true for multi-cellular organisms, where compaction of the genome is an important ingredient in the regulatory schemes used in generating and maintaining a multicellular body plan. Why is all this significant?
If H1 was indeed designed, given its minimal role in protozoa, it might constitute a very good example of front-loading evolution such that the initial eukaryotic state was prepared to evolve a multicellular state. In other words, the existence of H1 in protozoa may best be explained by the existence of H1 in metazoans. And that is one hypothesis that simply cannot be entertained, for the briefest of all moments, from a non-teleological perspective.
An important caveat is in order, however. Tetrahymena are fairly specialized protozoa and may not be representative of most protists. However, given that H1 is not essential in simple metazoans, such as filamentous fungi and also in specialized protozoa, we have good reason to suspect it might likewise be nonessential for less specialized protozoa. Here is yet another example where a teleological approach can generate experimental research. Instead of assuming Tetrahymena is unusual, and thus irrelevant, with regard to its lack of need for H1, we need to go into the lab and knock out H1 genes from other protozoans. And in keeping with the general argument of my speculation, we have yet another example of using a teleological approach to generate a prediction - if there is something to my hypothesis, then we will find other protists where H1 is not essential. In fact, we might even find some protists without H1.
Finally, keep in mind that "nonessential" does not mean H1 will have no role. Useless H1 is not a way to front-load (as useless things decay into nonexistence). Front-loading may entail giving a higher eukaryotic protein some role in protozoa to ensure it persists until something like higher eukaryotes evolve. But it is not until it is coopted into its primary designed role that it becomes essential.
[ 28 April 2002, 23:15: Message edited by: Mike Gene ]
IP: Logged
|
|
James A. Barham
Member
Member # 50
|
posted 29. April 2002 08:13
Mike:
I am curious to know what you think of Lynn Margulis's ideas. Let me explain what I mean.
First, I am wondering whether you are saying that front-loading might be necessary to explain ALL evolutionary change, or only the transitions to eukaryotes and multicellulars?
There are two problems here, it seems to me, that we should to distinguish. Prokaryotes exhibit some 20 different fundamental metabolic regimes, while higher organisms are all much more unified (all metazoans are "chemo-organo-heterotrophs," for example). So, the first question is whether the fabulous adaptability of prokaryotes themselves can be plausibly explained via front-loading, or whether ID theorists are willing to countenance the creation of novel functions at the prokaryotic level.
If you are, then Margulis's (and others') ideas about the role played by endosymbiosis in the evolution of higher forms may be a rival hypothesis to front-loading at higher levels, as well. It seems to me that ID theorists would do well to deal explicitly with the issues she raises.
IP: Logged
|
|
Drosera
Member
Member # 139
|
posted 29. April 2002 21:19
Mike Gene wrote,
quote:
Let's think about globin from a perspective of front-loading. Here's the design problem - how do you indirectly design a mammal-like organism by directly designing single-celled life forms?
Why would an intelligent designer bother with indirectly designing a mammal-like life form? Why not just make it, full stop?
And how do we know that mammal-like life forms are what was intended? Why not birds, or sea cucumbers, or redwoods, or lichens? Undoubtedly these all use a great number of proteins that have homologs in single-celled organisms.
Does "teleological perspective" tacitly assume "teleological with mammals (or perhaps humans) as the goal"?
Drosera
[ 29 April 2002, 21:20: Message edited by: Drosera ]
IP: Logged
|
|
charlie d.
Member
Member # 159
|
posted 30. April 2002 10:12
To elaborate on Drosera's point, I would also add that, no matter how potentially "genomically sophisticated" the progenote was, it is highly unlikely that any amount of front-loading 3.5 billion years ago could have accounted for such long-term unpredictables as geological phenomena (for instance, the size, or even eventual presence, of major land masses, their final distribution predominantly within the tropical, rather than polar, region, or major volcanic eruptions) and astronomical events (such as the K/T impact, and all the other asteroid impacts likely responsible for periodic major global extinctions) that clearly played a major role in shaping the current diversity of life forms on earth.
It seems to me that even within a front-loading context, sometimes designed to do away with the uncomfortable concept of human life as a random event, sheer chance would still remain one of the major forces behind us being here today (or ever) to consider the possibility. So, at best, the progenote's teleological features were seeded with a glimmer of "hope" that it would eventually develop into some sort of multicellular life form before the sun burns out (and it already took it half its life span, pretty much), but certainly no reasonable foresight of land animals, much less mammals, let alone us.
[edit: added "sometimes" to clarify that not all FLE hypotheses stem from lack of comfort with the role of chance in human evolution. I also noticed, re-reading the post, that neither John nor Mike (or anyone else) were ever even mentioned in it, directly or indirectly. I stand by its tone and content.]
[ 01 May 2002, 14:05: Message edited by: charlie d. ]
IP: Logged
|
|
Moderator
Administrator
Member # 1
|
posted 30. April 2002 12:04
Drosera and charlie d.,
Please respond to John Bracht and Mike Gene on their terms, not yours. I see no indication in their posts that indicate a "tacit assumption of teleology with mammals as the [ONLY] goal." Rather, Mike is using one example: we see mammals all around us, how would we design these mammals via frontloading. The same could be done for birds, or even multicelluarity.
Specifically for charlie d. The following presumption is frowned upon:
"It seems to me that even within a front-loading context, designed to do away with the uncomfortable concept of human life as a random event"
From my perspective this is a character attack, and you are essentially saying that Mike Gene and John Bracht are spineless cowards who are uncomfortable with the concept of human life as a random event. What if J. Bracht and M. Gene were both interested in front-loading concepts for empirical reasons? Does your stereotype allow for that?
The intentions of both of your posts (Drosera and charlie d.) are rather obvious, and Brainstorms is simply not the place to rehash the old and worn out "humans are not the center/purpose of the universe" argument. That can be done elsewhere.
I'd appreciate it if you'd address their posts and not try to fit them into your stereotypes. Nagging about superficial details is also not welcome.
Oh, and if you'd like to respond to me, do so via email: moderator@iscid.org
[ 30 April 2002, 12:36: Message edited by: Moderator ]
IP: Logged
|
|
charlie d.
Member
Member # 159
|
posted 30. April 2002 13:04
quote:
Mike Gene:
Let's think about globin from a perspective of front-loading. Here's the design problem - how do you indirectly design a mammal-like organism by directly designing single-celled life forms?
I think that Drosera and I were trying to address the above statement, but just in case, let me rephrase (and expand on) my comment, as per the Moderator's suggestion.
Any long-term evolutionary seeding "project" based on front-loading and a hands-off approach (that is, with no later intervention) has to cope with the overwhelming role that chance will play in the history of a planet, independently of how much careful genomic planning may have gone into engineering the seeding organism(s).
We already know for sure that life on earth has undergone a tortuous and perilous journey. Had the K/T asteroid been twice the size, possibly no advanced metazoan would have survived. Had continental drift pushed land masses to the earth's poles, not much of a land life would have likely developed (certainly not of the kind and diversity we know now). If life was contemporaneously "seeded" on Mars as well as on Earth, as it now appears possible, clearly the Mars experiment failed; it could have failed here as well.
So, to paraphrase Mike, the real question is: how do you directly design a seeding organism without really knowing what the environmental conditions are going to be like in a few thousand years, let alone a billion? Clearly, if the resources are somewhat limited, you'd hedge your bets, and stuff the critters up with everything you can think of, in the hope that it will turn useful at some point. If anyone takes a look at the kind of organisms that like to dwell in deep sea vents, this would not sound so implausible: their alien (to us) life-style must have been front-loaded too. Plus, any other life-style even moderately possible. Thus, the progenote(s) should have been loaded not only with genes that eventually became useful for us, but also with genes that just didn't have a chance to become useful, but may have in different conditions. May some of these genes have survived?
But then, what is the "purpose" of front-loading: letting life flourish anyway, no matter how and of what kind? If the seeding was "intelligent", purpose clearly IS the central question. Would the sophisticated bioengineers who designed the progenote be satisfied with a planet made of scattered colonies of bacteria and tube worms feeding off sulphuric acid deep at the ocean bottom?
Schwabe's kind of front-loading seems to me even more dry, purposeless and mechanistic than Darwin's RM&NS, so I do not think he would flinch at the idea of a deep sea worm-dominated world, but if front-loading is to be integrated within an ID framework, what teleological lessons should we draw from it?
IP: Logged
|
|
Art
Member
Member # 179
|
posted 30. April 2002 14:33
I think charlie d raises an extremely important point - the genome size of the front-loaded progenitor would seem to be imposingly large - that must be dealt with as any part of a research program into front-loading.
I have offered one possible solution here. There is another one that may be a way of re-stating some of the ideas put forth by charlie d. Obviously, the number of possible scenarios that must be planned for is very large. Moreover, it is reasonable to suppose that the unfolding of the history of the earth is not one that can be known from any set of initial conditions. Therefore, there must be a degree of uncertainty in the planning that must go into the frontloading. The best way to account for this is to build into the progentitor a capacity for effective production of large amounts of useful variability. This is in fact what we see in extant organisms. The catch is that these mechanisms are random in their actions. This randomness would seem to be insufficient to derive the CSI-laden results that are demanded of the progenitor. But this is true only if CSI-laden "things" are in fact what is needed here. If the goal can be met by CSI-poor or CSI-free "things", then we can accomplish the task at hand in a simple way, one that can be seen inextant organisms.
This latter scenario is what I might term a "zero-CSI" model for life. It has some direct experimental support (in the form of countless random combinatorial screens that have yielded biochemical and molecular functionality) and is a good fit (IMVHO) with frontloading scenarios. While such a model may seem to be contrary to current ID thought, I think that it deserves some serious discussion. The fit with frontloading is among these reasons.
IP: Logged
|
|
Mike Gene
Member
Member # 149
|
posted 30. April 2002 14:53
James,
Let me make some clarifications when discussing front-loading. The most extreme version of front-loading would attempt to equate the evolution from an original cell to the current biotic environment with the way a zygote unfolds into an adult organism. As such, evolution becomes strictly a deterministic process that can only be slightly perturbed by environmental factors. My views about front-loaded evolution (FLE) are far more modest than this extreme position.
First, it is not a question of necessity. It is a question of history and perspective. Whether or not a front-loading event was needed is not really important (IMO). The important (or interesting) issue would be whether a front-loading event happened. From the position of perspective, a non-teleological approach can only explain the present in terms of the past. But a teleological perspective, in addition to recognizing the utility of this approach, can also add foresight into the mix. This allows teleologists to raise the novel view that the future may also explain something about the past. Thus, can one generate a research program using this telic perspective?
Currently, I view FLE purely in terms of its heuristic value. The examples I cite above are not intended to support the validity of FLE, but to illustrate how we can rethink of the data from a different perspective. After one trains their mind in this new way of thinking, and after the data are explored from this new perspective, then one can come back and begin to make a case for validity. In the meantime, there is real heuristic potential in this approach (another way of showing the utility of ID).
Now, to the specifics of your reply.
You ask whether I am saying " front-loading might be necessary to explain ALL evolutionary change, or only the transitions to eukaryotes and multicellulars?"
This is a good opporunity for me to post what I posted before (as it also helps to answer the questions of Drosera and charlie):
I see front-loading as the investment of a significant amount of information at the initial stage of evolution (the first life forms) whereby this information shapes and constrains subsequent evolution through its dissipation. This is not to say that every aspect of evolution is pre-programmed. It merely means that life was built to evolve with tendencies as a consequence of both front-loading and the way evolution works (recall that evolution almost always uses/reshapes what it is given rather than invent novel solutions).
So what about the outcomes, as you ask? Since my investigation begins at the OOL, the outcome is the thing in question, not the starting place. If the evolutionary mechanisms were designed to exploit the active front-loaded state, just far out do these dynamics spread before being completely diluted by non-teleological processes? And even more interesting yet, if there exist these "dilution thresholds," do any exist that are again recharged with the investment of a new active front-loaded state (through another incidence of intelligent intervention)?
The possible outcomes of the originally front-loaded states are many. To name just a few:
a. The evolution of multicellularity
b. The evolution of plants, fungi, and animals
c. The evolution of plant-like, fungi-like, and animal-like creatures (creatures that function as analogs to what exists)
d. The evolution of invertebrates and vertebrates
e. The evolution of invertebrate-like and vertebrate-like creatures
f. The evolution of mammals
g. The evolution of mammal-like creatures
h. The evolution of humans
i. The evolution of human-like creatures.
Another way to look at it is by starting with what exists. FLE could translate as:
a. This specific biotic mix: " humans, platypus and jellyfish"
b. A subset of this biotic mix: "humans, platypus-like and jellyfish-like creatures"
c. An analogous mix: "human-like, platypus-like, and jellyfish-like creatures"
d. A subset of the analogous mix: "jellyfish -like creatures amidst other things non-teleological processes spawn."
The bottom line? Many have adopted Gould's line of thinking, where replaying life's tape would not produce the same world, to mean that evolution is thoroughly non-teleological or unguided in any sense. But I think there is MUCH middle ground that has simply not been thought about or explored.
As for bacteria and their different metabolic regimes, there is no reason to think front-loading through the OOL would involve the use of one cell or a clonal population of cells. In fact, a better design strategy would be to begin with a heterogeneous population of cells that can cross-talk. Many people think of front-loading involving "a genome" or "a progenitor" that is supposed to reach a very specific determined end. I'm talking about multiple cross-talking genomes that bias evolution toward certain trajectories.
For example, a large genome is not needed for front-loading. Why?
1. Genomes expand largely through duplication. The common interpretation is that duplicates can then diverge under random mutation and natural selection. Yet the newly duplicated genes rarely, if ever, acquire a novel, core function that is not already encoded by the original. The duplicates are fine-tuned, adjusted, tweaked, whatever, to form variants on the original theme. Yet to explain it all, we have to explain the origin of the original stem sequence, and its core function, that sits at the base of the duplicate tree.
One way to think about this is that a good designer would choose a sequence which could be duplicated and tweaked to exploit the "design potential" inherent in the original. Consider hemoglobin. Essentially, the hemoglobin function in mammals was encoded in the genome of protozoa billions of years ago. In other words, the myoglobin-like sequence found in these protists was designed so that it would be rather easy to "find" hemoglobin through a random search. This is front-loading. And it's interesting to me that so many proteins, supposedly selected to serve protozoa in a purely myopic fashion, work very well, often with only minor modifications, in serving humming birds and humans billions of years later.
In mechanical engineering, there is something called a mature design. A mature design is one which remains much the same over many years. I happen to think mature designs also exist in biology. The problem is that mature designs require either the input of intelligent intervention guided by conceptual connections or a long history of maturation at the hands of a blind watchmaker. Yet many mature designs exist at the base of life and also serve as the stem for a whole bunch of duplicative-tweaking. This is front-loading.
2. The second reason why a large genome is not needed is because of horizontal transfer. In this case, the genome size is the collective sequence of the population of heterogeneous cells. Such cells can trade, donate, and receive sequence that serves adaptive purposes. Horizontal transfer is common in eubacteria, and recent findings indicate likewise with archaebacteria. Is it common in protozoa? I don't know. But if protozoa were designed, my design through front-loading hypothesis would predict the answer is yes. I'll check into this some day.
As for the fabulous adaptability of prokaryotes, their fabulous ability to adapt itself may be part of a front-loading scheme. For example, there is often sophisticated machinery behind these remarkable mechanisms of adaptability.
As for endosymbiosis, this too may entail front-loading. For example, mitochondria are not needed for unicellular life nor unicellular eukaryal life (several protists have lost their mitochondria). But without mitochondria, it is extremely doubtful that metazoans would exist. Not only do mitchondria serve the energetic needs of such organisms, but also play important roles in apoptosis. More on this later.
IP: Logged
|
|
Mike Gene
Member
Member # 149
|
posted 30. April 2002 15:14
Charlie: Any long-term evolutionary seeding "project" based on front-loading and a hands-off approach (that is, with no later intervention) has to cope with the overwhelming role that chance will play in the history of a planet, independently of how much careful genomic planning may have gone into engineering the seeding organism(s).
You are thinking in terms of a deterministic mechanism trying to reach a very specific goal. Yet this is only one version of front-loading. I am not suggesting that evolution is predetermined. Instead, it's stacking the deck through front-loading.
Let's use the human genome as an example. Imagine that several billion years ago, some form of ETI seeded the planet with a consortium of microbes, rigged to increase the chances that a multicellular, sentient being would evolve. Imagine the same designers who seeded the planet now get their hands on the human genome. Here's the question: Would it look completely alien to them? If the answer is no, front-loading was a success. They'd be able to detect many functions and sequences they originally deposited. Their models of evolution may even be vindicated by the new functions or sequences that do exist through the shuffling and tweaking of their original design. More importantly, they might note how the genomic logic that was built into certain cells played out exactly as they intended (to exploit the front-loaded state). Again, this does not mean they intended to evolve a human being, only that the evolution of humans was not surprising. Front-loading makes a prediction that the "many possible outcomes" of evolution are not really that many. In a sense, if evolution was replayed again from the same OOL conditions, the beings that would emerge would be no more different from what exists today than any extant being is different from any other extant being.
We already know for sure that life on earth has undergone a tortuous and perilous journey. Had the K/T asteroid been twice the size, possibly no advanced metazoan would have survived. Had continental drift pushed land masses to the earth's poles, not much of a land life would have likely developed (certainly not of the kind and diversity we know now). If life was contemporaneously "seeded" on Mars as well as on Earth, as it now appears possible, clearly the Mars experiment failed; it could have failed here as well.
My front-loading hypothesis does not demand that this particular biosphere exist at this particular time. Clearly, many environmental factors such as these would pose an obstacle. But a good designer would already know this and thus design to get around such events (or even design features to exploit such times of crisis!). I think that if we begin to synthesize the ideas of Shapiro, Schwabe, and Morris, where smart cells guiding smart evolution employ front-loaded information to converge on biotic plans, the chaos you mention only thwarts attempts to predict the future, not shape it.
IP: Logged
|
|
James A. Barham
Member
Member # 50
|
posted 30. April 2002 17:28
Mike:
Thanks for your detailed reply. It sounds to me like the Margulis endosymbiotic scenario fits in well with your ideas (as it does with mine, I think).
I am now wondering what sort of empirical evidence we could appeal to in principle to decide which of our two views is correct (that is, front-loaded extrinsic design vs. intrinsic intelligent agency)? I wonder if there is any way to tell the difference, since we both see teleology as at work in all evolutionary processes, only in two different forms.
I guess (off the top of my head) that I would have to say that the front-loading idea simply goes far beyond any sort of actual engineering design that human beings are capable of. Obviously, we cannot design systems that are capable of acting intelligently, reproducing, adapting to circumstances, and persisting through eons. But, then, neither can I say what sort of physics is underlying what I call the intrinsic "intelligent agency" of the cell, so we are both in the same boat with respect to any sort of known, operational engineering or physical theory.
Any thoughts along these lines?
IP: Logged
|
|
charlie d.
Member
Member # 159
|
posted 30. April 2002 17:55
Mike:
if you are saying that given one or a bunch of (more or less simple) unicellular organisms, left at their own devices on an uninhabited, borderline comfortable planet for an incredibly long amount of time, a whole array of diverse uni- and multi-cellular organisms will arise in time, through natural means, and that these organisms may also include critters like us, I of course have no qualms with it. In fact, that's exactly what I believe happened. Is the deck stacked towards creatures "like us"? Perhaps, if you take "like us" with a grain of salt (if Earth's orbit period had been a few seconds faster, or slower, the K/T asteroid would have missed us and dinosaurs would possibly be carrying on this discussion). Certainly, starting from a bacterium there is a lot of free space to go up, and not much to get rid of, so probably multicellular life is indeed unavoidable, at the fringes of life (major asteroids permitting, of course).
However, you will agree that the sheer number of potential evolutionary routes is staggering, and any prediction meaningless. For instance, even if the ETI you talk about had given the progenote(s) proteins with the structural protein motif we now call the immunoglobulin fold, I would reckon that the likelihood for life on earth to develop an adaptive immune system with immunoglobulins (antibodies) like ours would still depend on the random integration of a trasposon within an Ig-fold-encoding gene in some mud-dwelling critter. That's not something you (or an ETI biotech specialist) can count on to happen - it just does. Of course, without a highly efficient immune system, extended life spans are very unlikely. And without extended lifespans, not much time to learn, and no need for a big brain for pretty much anything. So, the emergence of sentient beings may really be dependent on a transposon insertion in a weird-looking gene in a weird-looking animal (protovertebrates were not exactly at the evolutionary forefront at the time, quite a back-water, in fact).
The same pretty much could be said for almost every significant evolutionary event: sure genes are subject to duplication and divergence, but still duplications arise randomly, and divergence occurs according to local adaptive constraints. [I am assuming here you take the "purist", hands-off, quasi-darwinian front-loading position]
So, the question remains: no matter how potentially sophisticated the initial critters were, for how many alternative catastrophes/unforeseeable events did an ETI designer have to plan, in order to embed those first critters with the necessary devices they might (or might not - who knew) have needed to give rise to any kind of interesting specimens? Sure, a few well-thought-of genes may have helped along, perhaps, but at that point, why wasn't a penchant for obsessive self-replication already enough?
No matter what the bioengineers did, however, it doesn't seem to have helped our cousins on Mars, although the conditions there were quite good for a while: if they had hurried up, or had been built a little more efficiently, they might perhaps have succeeded in developing a better atmosphere, their planet would have been a little warmer by now, water liquid, and we'd already know many of the answers we are looking for (or perhaps we would have been colonized and used for plant food already). Perhaps, humankind's visceral distrust of biotechnology is a deeper-going adaptation than even Greenpeace supporters think. ![[Wink]](wink.gif)
IP: Logged
|
|
Mike Gene
Member
Member # 149
|
posted 30. April 2002 23:37
I'll get back to the front-loading discussion in due time, but I wanted to pause and mention the importance of the moderator's warnings above. I'm not going to follow up this reply, but I did want to bring it up in passing because I think it is very important.
The initial replies of Drosera and Charlie, whether intentionally or not, are the type of responses that do interfere with serious attempts to think about these issues. I recall a psychology experiment from the 1970s, where two groups of observers watched a short film of a traffic accident. Group A was asked, "About how fast were the cars going when they hit each other?" Group B was asked, "About how fast were the cars going when they smashed into each other?" Group B estimated higher speeds than group A, apparently because the word "smash" affected how they recalled the film. A week later, both groups were asked if they had seen any broken glass from the accident (even though the accident did not result in any broken glass). Again, members of group B were twice as likely to "recall" seeing broken glass than members of group A, probably as a function of falsely remembering a more violent accident.
Another experiment from the 30s showed people a picture of two circles connected by a straight line. For group A, the picture came with the caption, "eye-glasses"; for group B, it came with the caption "dumb-bells." Later, they were asked to redraw what they saw. Instead of drawing two circles connected by a line, many members a group A drew eye-glasses and members of group B drew dumb-bells.
How we label things and how we describe things does indeed shape how we see things. Thus, if critics attempt to label FLE as something "designed to do away with the uncomfortable concept of human life as a random event", either explicitly, or implicitly (through suggestive questioning), the critic is not only conditioning himself to see all arguments about FLE in this light, but is also biasing the readers' perceptions.
It would be interesting to conduct an experiment about this bias, as I am convinced that most readers tend to pay closer attention to the postings they think will support their position. Thus, the hypothesis is that a critic of FLE is more likely to pay closer attention to the criticisms posted by Drosera or Charlie than the original postings by John and yours truly. To test this, I'd bet that several weeks from now (and had the moderator not drawn attention to this and warned about this), several critics would "recall" John or me actually arguing that humans have a special/central place in the universe. This would be because Drosera/Charlie's act of labeling would skew their memories about what was said.
All of this then sets the stage for needless bad feelings, polarization and then posturing, a defining trait of all other forums devoted to these issues. While it would seem to me that critics should be welcomed with open arms on this forum, we need to distinguish between the type of criticism that merely plays into stereotypes and thus leads to bad feelings, confusion, polarization and posturing and the type of criticism that works to weed out bad ideas and inspire the development of better ideas.
So I would like to publicly encourage the moderator (someone I do not know or talk to behind the scenes. The heavy-handed approach will likely elicit some confusion and bad feelings among some, but it is essential to developing this forum into something that is valuable and unique. And think of Brainstorms not in terms of next month or next year, but in terms of ten years from now.
PS: In case anyone "suspects" I am uncomfortable with human beings as the products of random events, I suggest they take in my own eccentric theological views here . It should become clear that nothing about randomness in our history causes me any psychological or theological discomfort.
Okay, that's off my chest...now back to FLE...
[ 01 May 2002, 01:39: Message edited by: Mike Gene ]
IP: Logged
|
|
Moderator
Administrator
Member # 1
|
posted 01. May 2002 01:02
Mike:
Your post is well taken and does a good job at articulating one of the reasons I am a heavy handed moderator. However, in noting that I agree with you (we want a particular kind of person at Brainstorms: one who is interested in developing ideas and providing constructive criticism) I would appreciate it if the discussion in this thread would get back on focus.
I see a lot of potential in this topic. It would be unfortunate if I had to shut the thread down because of diversions. All posts from here on out need to be on topic.
IP: Logged
|
|
charlie d.
Member
Member # 159
|
posted 01. May 2002 09:42
Well, far from me to take the discussion off course, but since my statement has been called into question, I think I deserve a chance to respond. I'll be brief and to the point.
1. I never stated or implied that John or Mike are uncomfortable with the role of chance in human origin, much less that they are "spineless cowards" as the Moderator regretfully interpreted my statement. I just said that while FLE is supposed to take away the role of chance as it relates to human origin, to a higher or lower extent depending on what kind of FLE one subscribes to, it effectively only eliminates a small part of it, because the way life evolved on this planet still depends on a series of non-biological random events.
2. By definition, intelligent front-loading involves a purpose. Whether front-loaded life on earth is the result of an alien biological experiment, or a product of divine planning, the moment we are talking about an active intelligence, I do not see why raising the issue of goals is shifting the topic. In fact, it was John who brought the issue up multiple times in his post, for instance here:
quote:
It makes sense that an extremely clever engineer would design various parts to be able to function in very different systems as the entire organism develops with time. Perhaps relaxin played some role in earliest prokaryotes and was intelligently pre-adapted to its vital role in enlarging the birth canal once multicellularity was reached.
Clearly, if you want to identify what front-loaded genes a designer put in the progenote(s), and why, you've got to have some hypothesis about its goals. For instance, why is multicellular life preferable to a designer? Why the need for relaxin: egg-laying, live birth? Why not reproduction by budding instead?
3. Finally, I agree with Mike that the way we label issues influences how people read and remember them. That is why I resent the way the Moderator chose to interpret my post: that is entirely not the way I meant it, and his very public admonishment will now give the readers the impression I am some kind of board troll to be dismissed, while I think I raised relevant issues in an urbane tone.
[Before I get nailed again, I sent the Moderator a private message about this yesterday, as he/she suggested, but he/she has not read it as of now]
4. I will be more than happy to go back to the discussion, if anybody has anything to add to it.
[ 01 May 2002, 10:49: Message edited by: charlie d. ]
IP: Logged
|
|
|
Printer-friendly view of this topic