Modularity, A distinguishing property of life

So... kind of like you can smash up a radio and pull out working transitors, capacitors and bits of wire?Seems to me the defining feature of life is not the seperatability of features but their interconnectedness. Chemicals produced as by-products in the liver are detected in the brain, vesicles carrying molecules for secretion into the blood stream are also used to carry membrane proteins to the cell surface, amino acid sequences that control the structure of proteins are augmented by sequences that control the destination of that protein.

Hi Filameter,It's not true that when you smash up a silicon chip you get nothing that works anymore. The transistors which once provided the many and manifold operations of the chip are still there and would still work if you separated out and wired them up once more. That we do not do so reflects the comparative ease of construction and usefulness of these fragments not their operational integrity.Integration hasn't changed the fundamental form of the systems, it is matter of efficiency of cost and speed that drive them but look closely at how chips are designed and you'll find that the same principles (admittedly multiplied many times over and augmented by new ideas) operate in modern chips as once operated in circuit constructed with vacuum pipes. No, this is just not so. The way lifeforms are constructed both on the embryological scale and the evolutionary scale doesn't operate like that. A simple example comes from embryological experiments in which sections of limb bud from one embyo are transplanted onto another - you'll find that the new bud duly acquires the requisite nerve fibres and neural connectivity. At a very basic level developmental processes are closely integrated and tied together in a way that defies seperation.This is a hallmark of evolutionary processes, and contrasts with designed systems, because in an evolutionary process things all things are present and can act upon one another you end up with a multitude of pleotropic genes that influence completely unrelated tasks. Organisms are not modular, everything leaks into everything else.

I disagree, the notion that programs should be modular so as to promote re-usability is a terrible red herring that massively undersells the concept. The reason that we programmers construct software in a modular fashion is because it means that they can be treated in isolation. In modular software I can direct my attention to the small section of code I am looking at without worrying that global variables are being mysteriously tampered with far from my sight.Modularity is also an important feature of other designed objects. In chip design, the modules dealing with different instructions are separated out; in car design, you don't mix the gear box with the differential; in house design you don't run a gas pipe through the middle of your radiator.

Wrong. Abiogenesis is an empirical fact. We know that there was no life 13.7 billion years ago, and no life on Earth 4.5 billion years ago. We also know there is life on Earth now. Thus, by simple deduction, at some point in the last 13.7 billion years life formed from non-life - abiogenesis - further, given the remarkable unlikelihood of life surviving to cross space and seed earth, it's most likely to have formed on Earth in the last 4.5 billion years.

There is no faith involved; it's deductively certain that at some point in history life came form non-life. Because we know there was no life at one time, and there is life now.

Yes, science excludes the possibility of the supernatural because it's silly. There's nothing special about abiogenesis in this regard. Just as we reject the notion that invisible fairies are pulling the apple that falls from the tree to the ground because its silly, we reject silliness in other areas.

This is false. Look out of your window, do you see a tree? That tree, right now (assuming it's daytime where you are) is converting non-living matter into matter. It's taking inorganic compounds, turning them into organic compounds and building living things from it.The fact is that the more closely you investigate, the blurrier the line between living and non-living becomes. Living things are just chemistry; very complicated chemistry, granted, but chemistry none-the-less. See, this is a silly argument. Not being able to reproduce things in a lab says nothing about their occurrence in nature. We can't make a star in the lab, but there they are shining in the sky; we can't make a volcano in the lab, yet they happen all the time. Our ability to recreate things in the lab tells us of our limits not the limits of nature.

This is simply wrong. Plants absorb little or no carbon from the soil (they do absorb water , nitrogen compounds and phosphate primarily, along with some other trace elements); their source of energy is sunlight, which they employ to combine inorganic carbon (in the form of carbon dioxide) and water into sugars which are then further metabolised into the full variety of organic compounds including amino acids and fatty acids. Trees are, quite literally, made of rain, sunlight and air. Way to miss the point: our inability to reproduce something in a lab is meaningless as to the possibility of something. Especially where elements of scale are involved. Neither of these experiments tried to produce life. What they did was remarkable: they demonstrated that organic compounds can be formed by simple inorganic chemistry. A fact since confirmed in a great many ways both in the laboratory and through observation of the universe. No, most currently extant life uses precisely 20 amino acids in protein encoding. This is very much not the same things as 'must be present in living organisms'. Do you understand why?Edited by Mr Jack, : qs tags, not quote tags

Prove it. This is simple assertion on your part and given your ignorance of such basic biology such as how plants produce organic compounds I've got to wonder what credibility you have to make such assertions about biochemistry. We already know of organisms that use more than the standard 20 amino acids, so how you can you so confidently assert that this number - which we already know can vary - must be present for life to function? Wrong, I proved it way back in my first post:

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Wrong. Abiogenesis is an empirical fact. We know that there was no life 13.7 billion years ago, and no life on Earth 4.5 billion years ago. We also know there is life on Earth now. Thus, by simple deduction, at some point in the last 13.7 billion years life formed from non-life - abiogenesis - further, given the remarkable unlikelihood of life surviving to cross space and seed earth, it's most likely to have formed on Earth in the last 4.5 billion years.

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Once there wasn't life, now there is life ergo at some point life must have formed out of something non-living. Life, like many properties of the natural world turns out to be "fuzzy"; there is no hard boundary between living and non-living. And the harder you look, the harder it is to define. Sure, you can cobble up a bunch of criteria, but you'll find soon enough that they either exclude some kind of life you'd like to call life or include something you want to claim isn't. This is exactly as we should expect, because ultimately life isn't some mystical voodoo; it's chemistry.

Who? Seriously no-one has said they know how it happened, only that it happened.

Abiogenesis is not self-evident. There's nothing a priori that means life cannot always have been, we only know that life hasn't always been by applying science. I trust science because it has an incredible track record of success, methodology that both makes sense and can be demonstrated to work and produces coherent and understandable results that can be independently verified. Against that you have making some stuff up - which is exactly what any designed imagined into the scene is. Trouble is that once you've accepted making stuff up and magical mystery designers into your idea of knowledge abiogenesis is no longer justifiable as a necessity, and science is no longer trustable. Maybe it always was, and the magic just makes it appear like it isn't? Maybe that cup didn't fall to the ground 'cos of gravity but because the pixies made it so.I'll take science with its proven track record of success, and coherent methodology and outlook over the machinations of incomprehensible magic, thank you.Oh, and this isn't a matter of "materialist philosophy", it's a matter of pragmatically and consistently applying principles that work.

Ah, Newton, a man who lived before modern science, before Darwin, before we knew of the changing heavens, before the Big Bang was discovered - most surely is his uninformed opinion relevant today! I'm being slightly hyperbolic, I'll admit. However, the point about abiogenesis is that there is nothing in the reasoning which doesn't happen in other science; it's not a special case. If you think that magic is entirely justified as an explaination in the case of abiogenesis then why isn't it equally justified in the case of gravity?

I am. Abiogenesis is a fact, the inevitable conclusion of simple deduction based on two observations: the current existence of life, the past non-existence of life. We know, for a fact, that abiogenesis occured.What we don't know is how.

I don't think the lack of complete certainty should scare us off using the word 'fact' in science where appropriate. Complete logical certainty is not a possibility in life for, well, anything so we can either reject the word fact as meaningless in all contexts and instead use convoluted language dripping with disclaimers or adopt it where things they have been confirmed beyond all reasonable doubt.Abiogenesis is certain beyond all reasonable doubt, thus I shall continue to use the term 'fact' for it.

Obviously? You think it's obvious when something dies? Hardly. Consider a seed, it's sits on the shelf doing nothing for a thousand years and then, when planted in the ground and watered, it grows into a plant. Clearly then, a seed is alive for a thousand years but it neither moves, nor grows, not reproduces, nor respires. Now consider a second seed, left on the same shelf for a thousand years. When you plant it, it does not grow. At some time in those thousand years that seed switched from being living to non-living. It died. How do you think you can tell? What "obviously" changed to its opposite?You may think that's a contrived example, but it's actually very similar to the behaviour of some fungal spores and bacterial cysts - which are better examples but probably less familiar to you.Life at its edges, including in its beginnings and in its endings is not a clear cut thing. Not at all. Ask any doctor.