Modularity, A distinguishing property of life

Hi Filameter, and welcome to the fray.Most excellent first post. One other aspect of good design is redundancy, especially when it is necessary for preservation of life. In designing a ship for instance, there are several places where redundancy is used, with the double skin of oil tanker barges as one example where double wall are used. This is actually a design element to protect the adjoining rooms when a single room dies and needs to be removed without disrupting the other rooms. Just remove the whole block, and the rest can continue to function.This may be more analogous to a building in a city rather than a room in a building, as the cell is built of of blocks to form a whole: the removal of a cell is similar to the demolition and removal of old buildings in a city, while the city continues to function. Then new structures added in the vacant location can improve the functionality of the city, while retaining the overall modular building structure.The city also evolves new arteries and means of transportation of things critical to the living and growth of the buildings. Modulating the speeds at which various mechanisms operate, through enzymes and hormones, etc., and switching energy usage from one system to another also occurs in the cell structure of organisms.Just some thoughts.Enjoy.Edited by RAZD, : moreEdited by RAZD, : eglsh+

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Hi Hyroglyphx, Is a virus a zombie?Where you draw the line depends on how you define "life" - however there was likely a period of time when pre-biotic chemicals exhibited some of the features we normally consider part of life as we know it.There are several viruses today that display some attributes of life, as they are able to replicate molecules. They are not normally considered "life" because they don't use a cell membrane. Both can replicate molecules. There are many self-replicating molecules, and there are RNA molecules that work in tandem with a sister molecule - each replicates the other.See the Self-Replicating Molecules - Life's Building Blocks (Part II) thread for some details on this process and how it fits into the "RNA world" hypothesis for the development of life from chemicals. Define life. Cite your sources. Show us the line. Message 69
I agree that in science No webpage found at provided URL: abiogenesis, or origin of life, is generally considered to be the study of how life on Earth could have arisen from inanimate matter.Personally, I am not in favor of equating supernatural creation of life with abiogenesis, and would rather state that:(1) 4 billion years ago there was no life on earth
(2) 3.5 billion years ago there was life on earth
(3) there is no known record of the beginning of life, no fossil evidence between (1) and (2)Therefore, either (A) life developed from inanimate matter (abiogenesis) or (B) life was brought here (creation or panspermia).(A - abiogenesis) can be studied by science, (B₁ - creation) cannot, (B₂ - panspermia) could be studied if there was a second example of life.Enjoy.Edited by RAZD, : addedEdited by RAZD, : clrty

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Hi slevesque There are several mathematical concepts that are designated by letters:π = 3.1415926535897932384626433832795 ... is the basis for calculating circumference and area of a circle, shows up many places.e = 2.7182818284590452353602874713527 ... is the basis for logarithms and is commonly used as the base of exponential functions, shows up many placesi = (-1)^{^1/2} ... is the square root of -1 and is the basis for imaginary numbers, shows up many places.y = ax^{^2} + bx + cx = (-b ± (b^{^2}-4ac)^{^1/2})/2aIf b^{^2} < 4ac then you are solving for a square root of a negative number, which is normally solved by factoring out -1 and then taking the square root of the remainder, and placing an "i" after it to designate the square root of -1.Edited by RAZD, : end clrtyEdited by RAZD, : for my imaginative friend

Hi Hyroglyphx, I notice that Percy and Dr Adequate have already answered, but I have a few comments to make as well. Curiously, science does not draw a line, but talks about a number of features that are common to life, but that it gets sticky when you talk about (a) formation of life from chemicals on an ancient earth or (2) formation of life on other planets.Here is a (rather wordy) article that discusses the multiple problems with simple definitions: The Definition of Life, By Joseph Morales:

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... I would argue that it would be a good thing to have a workable abstract definition of life, and that such a definition need not be wholly arbitrary, but can be defensible to a degree. However, the point is not to describe some sort of metaphysical essence of life. Rather, the point is to define life so that the term can be usefully extended to situations we have never before encountered.
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Whenever biologists try to formulate definitions of life, they are troubled by the following: a virus; a growing crystal; Penrose’s tiles; a mule; a dead body of something that was indisputably alive; an extraterrestrial creature whose biochemistry is not based on carbon; an intelligent computer or robot. William Poundstone, The Recursive Universe

We will be searching for a definition of life that is useful. In order to be useful, the definition should meet the following criteria, so far as possible:

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And he goes on to list a bunch of criteria for evaluating a definition of life, along with common problems with the various criteria discussed.Interestingly, to nod at the topic, none of the definitions noted, nor any of the criteria for testing a definitions, mention modularity as a distinguishing property of life. Fascinatingly, I do not. Take the Von Neuman Robot ("Vonny") concept: a completely self-reproducing entity that makes copies of itself, taking up raw material and forming it into the bits and pieces of another Vonny. The difference between this and a prokarytote single cell organism is ...? They are both replicating, I'm sure you would agree, but what makes one reproduction and the other one not? My working definition (it's a work in progress) is a threshold definition, where there are more aspects involved that we normally associate with life than aspects we normally associate with non-life.Thus if we make a list of 8 or 10 "normal aspects of life" and assume for simplicity sake that the "normal aspects of non-life" are the obverse of the former, then we can develop a model for when the threshold of life is crossed. Love those absolute pronouncements. A single cell bacteria is living according to most working definitions, but it does not contain cells. Let's say it has a membrane\shell, a container for the thing contained. More complex forms of life have more complex containers. A meaningless statement, or it begs the question: growth_life as opposed to grows_non-life, so we can tell life because it is life? Replication, let's keep it simple, however, to make it a little more complex, let's say self-replication, that formation of similar objects by other means does not count. Again, decay is a function of life, so you are saying we can tell life because it is life.Interestingly, I would say that a more important criteria would be the continuation of life independent of individuals, that individuals need to be linked to parents in a continuous trail, so a single individual contained replicator is not sufficient to be alive, it needs to be part of a continuous chain of life.This may seem problematical for an original first life, however the development of that chain is attached to and contains that first individual, and that without descendants it is not life. That's it?I would add:

exhibits negative entropy - it consumes matter and/or energy and creates organization.

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stasis - the individual exhibits stasis, staying relatively the same over extended periods, relative within the container compared to outside the container. The insides stay inside.

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reaction - senses and reacts to external stimuli (sunlight, food, danger, etc)

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adaptation - imperfect replication leading to selection to adapt to change, getting more into defining life of a population rather than of an individual.

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... for starters ...

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Perhaps a simple way to state it is: a population of similar objects capable of evolution.

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So let's say the list includes, but is not limited to:

1. Contained within a shell or membrane
2. Self-replication
3. Common Ancestry and continuation regardless of individuals
4. Negative entropy
5. Individual stasis relative to surroundings
6. Reaction to stimuli in surrounding ecology
7. Adaptation of population to changing or different ecologies
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And that any system that exhibits four of these items has crossed the threshold, has gone from non-living to sort-of living. Notice that a virus passes several of these criteria, but then I believe viruses are left over from the RNA world life forms. Also notice that the Vonny also passes several of these criteria: this does not bother me, as I feel it is entirely possible to fabricate life, and whether one does it with molecules or machines is irrelevant.

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If it does come to that, then we will likely see modularity as a distinguishing property of life, as it certainly is a property of design for easy maintenance.

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Enjoy.

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Edited by RAZD, : clrty

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Edited by RAZD, : includes

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Hi Hyroglyphx, it seems were back to the issue of what life is. Curiously I don't see it as a definition but a set of criteria that a definition needs to meet, and which demonstrate that none can be conclusive. And that interpretation room means the resulting definition must necessarily be distinctly gray. Most of mutations are replication errors. When more parts are replicated you have more probability of errors, but the basic mechanism is still the same.Mules and other sterile hybrids contain genomes of many genes, yet they are not able to reproduce - are they alive? Then you need to define what a "cell" is in a way that does not require it being a part of life - you are falling for the same mistake you did with growth not grows. Because what you are saying is that the difference between life and non-life is that life grows the way life grows and non-life grows the way non-life grows: you distinguish between the two groups based on your conclusion.When I lose weight (one of these days ...) does that mean I'm dead?It's perfectly fine to have growth be one of the many aspects of life, but with that is the realization that (a) some non-living systems exhibit growth in a many very similar to the process in life, and (2) not all living things exhibit growth, and you cannot define it in a way that excludes the former and includes the latter. Decay is due to the consumption of organic molecules by organisms, the same kind of consumption that involves non-organic molecules, and it is NOT a property of dead organic matter. This is why we have mummies in peat bogs, in desserts and in ice and amber. Do you know what a spore is? Spores have been found in amber that are millions of years old, yet can revitalize into an organism.Is it dead?Do you know how Monterey Pine's reproduce?

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In others, the fire climax pines (e.g. Monterey Pine, Pond Pine), the seeds are stored in closed ("serotinous") cones for many years until a forest fire kills the parent tree; the cones are also opened by the heat and the stored seeds are then released in huge numbers to re-populate the burnt ground.

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So is the fire a part of the life cycle? Some say viruses are not life because they depend on something outside themselves to reproduce - how is this different from the pines needing fire? Are you saying we can arbitrarily eliminate because of our organic bias? Can you eliminate Vonny and not eliminate some other known life forms? Can you eliminate viruses and not spores? So how many aspects do we have now? Does everyone need to be present? Or are there some that are optional, but where one or more of the optional aspects are also typical of life?Still looks grey to me.EnjoyEdited by RAZD, : clrtyEdited by RAZD, : ?Edited by RAZD, : diet

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Hi slevesque, you're caught in a logical fallacy here It doesn't. There is a high proportion of scientists that believe in god/s. They, like Newton, did not let their belief interfere with the scientific analysis of information. No, it's not still that. The field has blossomed with the addition of xenobiology - the study of life on other planets, and how to identify it - and the study of self-replicating molecules - see Self-Replicating Molecules - Life's Building Blocks (Part II). There is a mechanism that makes it non-random: molecules only bond in certain ways, so two molecules don't bond in any random pattern. Then you're in luck - see the Self-Replicating Molecules - Life's Building Blocks (Part II) thread.Enjoy.

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hi themasterdebator, welcome to the fray. type [qs]quotes are easy[/qs] and it becomes: or type [quote]quotes are easy[/quote] and it becomes:

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quotes are easy

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also check out

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(help) links on any formatting questions when in the reply window.For other formatting tips see Posting TipsUsing these aids helps sort out what you say from what your quoted sources say. Not really sense that is common, rather it is more often common ignorance embedded into cultures. So far, every element that I have seen that has been proposed to differentiate life from non-life has examples to life that don't qualify and examples of non-life that do qualify, and it is only when you compile a rather extensive list, and then back off to a level where there are no such overlaps, that we can get a common understanding, however this ignores the gray landscape in between.Enjoy.

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Rebel American Zen Deist
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Hi again Bio-molecularTony, still making those absolute(ly wrong) conclusions I see. Life = not life? This is the fallacy of begging the question so that only your "alternative" results in life. Too bad most of us can see the mental gymnastics you employ to justify your position for what they are: confirmation bias and denial of reality. Thus your "argument reduces to life is either not life or: Sorry, I'll takes #5: none of the above. I don't think life itself is supernatural at all: it seems to obey common laws of chemistry and physics.Curiously, life is, in fact, complex chemical reactions. For some people, I suppose, they are complex enough to be called machinery - this is what (all) you have done, after all. Interestingly, calling them machinery doesn't make it so. What we see from numerous experiments is that it is not necessarily designed, as the parts could have assembled in the same manner as we see for pre-biotic cell like structures and pre-biotic self-replicating (complex) molecules. The simple fact that this single alternative is not represented in your list demonstrates your list, your thinking, is incomplete, thus there could be several other possibilities not limited by your scope.Enjoy.

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Hi Larni, What he is trying to say, he is also trying to hide behind a baffle of words, a plethora of verbosity designed to appear to have meaning.

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Intellectual design will always be complexity technology and complex non-natural engineering is always intelligent designed technology.

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[interpret]Intelligent design results in complexity, therefore complexity is a result of intelligent design.[/interpret]Bad logic disguised as actual thought.Enjoy.

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Hi Filameter, some posting tips:"If all enzymes were active all of the time, would this overload the cells and create a complex chaotic mess?" - traderdrewThis forum has some quote techniques that add to the readability of the posts:type [qs]quotes are easy[/qs] and it becomes: or type [quote]quotes are easy[/quote] and it becomes:

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quotes are easy

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You can also type [qs=traderdrew]quotes are easy[/qs] and it becomes: also check out

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(help) links on any formatting questions when in the reply window.For other formatting tips see Posting TipsEdited by RAZD, : .

Hi traderdrew, you have some false information. Stromatolite - Wikipedia

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Stromatolites (from Greek στρώμα, strōma, mattress, bed, stratum, and λιθος, lithos, rock) are layered accretionary structures formed in shallow water by the trapping, binding and cementation of sedimentary grains by biofilms of microorganisms, especially cyanobacteria (commonly known as blue-green algae). They include some of the most ancient records of life on Earth.

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Stromatolites were much more abundant on the planet in Precambrian times. While older, Archean fossil remains are presumed to be colonies of single-celled blue-green bacteria, younger (that is, Proterozoic) fossils may be primordial forms of the eukaryote chlorophytes (that is, green algae). One genus of stromatolite very common in the geologic record is Collenia. The earliest stromatolite of confirmed microbial origin dates to 2,724 million years ago.[2]

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Stromatolites are a major constituent of the fossil record for about the first 3.5 billion years of life on earth,[3] with their abundance[verification needed] peaking about 1,250 million years ago. They subsequently declined in abundance and diversity, which by the start of the Cambrian had fallen to 20% of their peak. The most widely-supported explanation is that stromatolite builders fell victims to grazing creatures (the Cambrian substrate revolution), implying that sufficiently complex organisms were common over 1 billion years ago.[4][5][6]

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So it is not the microorganism that is fossilized, but the debris of microorganisms living, and the date is 3.5 billion, not 3.8. Actually, it has been done several times - see Irreducible Complexity, Information Loss and Barry Hall's experiments and A True Acid Test. In the Dover trial Behe admitted there was no IC system that could not be explained by known evolutionary processes.Page not found | ACLU Pennsylvania Which doesn't address the way molecules combine or the fact that life doesn't have to assemble all at once. Curiously, an astronomer is not a molecular biologist. If you want to argue about the probability of life (not the topic here) try the old improbable probability problem.Enjoy.

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Hi Mr Jack, Message 11
Message 12I agree, and posted similar in Message 3We can consider the city, where buildings are cells that can be removed and replaced, either with similar structures or with different structures. It is modular, and it is integrated by the communication systems, roads, water and sewer lines, etc.Some cities are designed, some are natural developments over many generations. Both exhibit modularity and integration. Both exhibit redundant features.Enjoy.

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Hi traderdrew,... I interrupt the topic for a small quibble\clarification ... It was an organism that produced waste product (stromatolites) similar to what we observe today from many species of cyanobacteria, however we have no fossil of the organism itself.This is valid evidence for life - waste product from metabolism - however we have no idea how complex the organism was (did it have a cell membrane of double lipids? did it function with DNA?), all we can surmise is that it reproduced sufficiently to produce piles of waste product. We can surmise that it probably was similar to modern cyanobacteria, but that is a large room.No need to reply - this is just an off-topic clarification.... I now return you back to the topic, "Modularity, A distinguishing property of life" ...Enjoy.