h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I don´t think morphic resonance sounds like anything but bogus.

Anyway, I didn´t think you were a creationist.(BTW the book was called What Is Creation Science II ) I just thought I should state that I don´t know wether to believe in evolution anymore. And as far as replicating goes, if a crystal can then it can´t be all that hard. And the "one wonderful day" was just because I am alive so I feel life is a nice thing. I don´t believe there was a meaning with it. And replicating molecules has an advantage in the sense that after a short while there is a lot more of them than the others.

How indeed can one molecule be selected for rather than another. All the ideas about how life started seem so strange and unlikely that the notion of molecules busily forming chains and doing a slippery conga through the primordial slime, as vague as it is, seems to be a favourite among biologists.

Never heard of morphic resonance before. Is it like voodoo?

Isn't the formation of crystals relatively simple? How might the construction of proteins be similar?

I've been giving turtle's question about what makes life different from non-living matter. One thing is, life tries to continue in a way that, say crystals don't. Crystals grow if the right materials happen to come their way but life goes out actively seeking materials to grow and replicate. Where does that /will/ to replicate come from? We have a survival instinct but we're complex. How does a slimy little chain of molecules get the will to live and replicate?

Glad you're happy to be alive Xanatic

Animals do that Sal but plants, moulds and algae simply sit there and absorb the stuff around them, if the right nutrients run out in their locale, they die. I suspect life did not start out actively seeking out the required materials, it just happened to find a nice place to get them, after a long time, some mutations led to beings that found it advantageous to move about and find the required materials...

Proteins aren't the replicators though, DNA (and possibly before that RNA) is. The backbone of DNA is simple a helix of linked phosphate-sugar-phosphate, it is possible that that may have grown on a crstal face that attracted said groups.

Anyway, crystals grow, they do not replicate, that's a different thing. There's a quite a lot of chemists around the world who are testing simple replicating systems to see if simple 'evolution in a test tube' can be acheived.

Hello,

Well, I think it's not really wise to ascribe will to basic chemical reactions. The prion will spread itself just through its nature, as does the bacteria or simpler forms of life. Obviously the evolution of will and consciousness is a tricky one (I don't buy that we're the only animals not driven solely by instinct), but one we really don't understand yet. It's fascinating though, but not really part of this question.

What's fascinating to me is how we ascribe motive to actions. So in AI, they have robots that now follow basic rules of leg movement, but seem to making more complex decisions and thoughts. Or if you want, we think of evolution as almost an active process and will even describe it in anthropic ways. I think it's part of our basic cognitive mechanisms. But I suppose that's also not really pertinent.

Yours,
Jake

"Will" is the wrong word. "Drive" is too anthropomorphic. How about "propensity", "tendency", "predisposition"?

I introduced the idea of crystals, earlier, to try out the idea of things happening by "habit", which is itself too strong a word. Probably.

Molecules can develop "habit", but only if the right materials are available. Non-organic crystals will grow more readily if there are already such crystals present - it's called seeding, I believe. Some organic compounds exhibit the tendency to form long strings - will the existence of one protein molecule make it more likely that other molecules of the same sort will form?

After enough time, after the development of enough slimes made up from a small number of molecules which happen to form in the same micro-environment and make up a "productive" slime, can the precursors of RNA be a possible product?

And as soon as there is such a meta-molecule, which has an effect on the construction of other molecules, have we got what we need? There could have been millions of types of RNA, some of which instantly backed themselves up non-productive blind alleys, some of which produced turpentine when there was not yet any need for it, some of which produced poisons which wiped their own little slime sites out.

But some of them could have started to reproduce molecules which didn't do any harm. Some of these molecules, by chance, could have acted as catalysts or even (later?) enzymes, to produce third, or fourth, or fifth... molecules (in productive chains or webs...?) which increased the likelihood of the RNA-type molecules being more plentiful. Others could have "produced" more chemical feedstock.

I think evolution could just about come in here - a variable environment having a differential effect on the likelihood of appearance of "entities" - instances of a particular molecule.

Very good Mund, exactly what I imagine myself

BTW, you can seed any crystals, organic crytals will grow on a seed crystal just as readily as inorganic ones will

The molecules didn´t have a "will" to reproduce. Some just happened to do it, and they survived. And besides, how do we even know we have a will of our own?

Pretty convincing speculations, Mund

You're all absolutely right -"will" was the wrong word (don't want to plop into philosophy). My vocabulary seems to lack a suitable word for what I mean. "Propensity", "tendency" and "predisposition" are better. I thought of "striving" or "questing" - a sort of active seeking but not involving any degree of conscious will.

I was really thinking of how life seeks to continue in a way that inorganic things don't, Orcus. It's true that trees don't move about but their roots and branches reach towards sources of nourishment. Bacteria don't always just die when their food source runs out. Some go into a dormant state (L Form?) and just wait for conditions to improve - like Bacillus 2-9-3 that lay dormant for millions of years. I think rickettsia and some viruses can be blown for hundreds of miles on the wind. Anthrax can remain viable in soil for a long time. Things like moulds don't move but they release spores to carry on moulding elsewhere. Even life forms that cannot move have ways of getting the next generation into new environments. Life does have definite strategies for continuing where as crystals don't. That sort of "striving" or whatever you decide to call it must have started at some point. I imagine it started early. It's so much what life *is* that it must have been there from the very beginning of life, mustn't it? If the slimy wriggly stuff that was the beginning of life didn't actively seek what it required in order to continue it's existence or replicate, could it be called life? I suppose there must've been some key moment when the precursor of life became actual life. I imagine that would be the moment when the collection of molecules actively sought to continue and replicate. Hmmm, well I guess that's not very different from what you were saying anyway.

I think I've read something about the evolution in test tubes. Something about synthetic RNAs that often end up making what look like instructions for a ribosome - something like that. Wow.

The "moment" at which non-life turns into life is interesting, but if it was just one moment then it would have had to be just one place, and I can't believe that it happened only once. Surely the chances of a single, microscopic upwelling of molecular development surviving to develop are so slim that we wouldn't be here.

The definition of "life" has been tried many times, but "actively seeking" to continue and replicate is going too far again.

Can a virus actively seek out an environment in which it can multiply or does it go with the flow until it either hits one or doesn't?

More complex forms such as bacteria may have evolved mechanisms to move towards light, towards warmth, or to change their chemistry to a "standby mode" if the environment gets really harsh, but are they actively seeking?

Does a molecule seek to replicate itself? If it's salt or sugar it simply can't: if it's DNA it can do nothing else if the environment is right.

We're speculating about molecules which somehow happened upon a combination of structure and environment which led to the development of replication mechanisms. But the logical point at which some of this development could be called life is still elusive.

A bacterium (or indeed any cell) has two environments - internal and external. Most of its chemical activity, which is most of its activity, takes place in the internal environment, protected by a lipid wall from the external environment.

The development of walls within which chemical activity and mutation can occur must have been one of the great logical change points, but again - can you imagine that it happened only once? Could the world's life forms be descended from a single ur-bacterium?

Compared with that, complex cells and multicellular creatures seem almost straightforward, but we have so many examples of almost every kind of development observable in the world around us, so we can imagine how things might have moved from one state to another.

I'm still trying to avoid any words which imply that molecules or "simple" organisms can have any kind of will or volition. They may have developed survival mechanisms, but to talk about them as strategies, as Dawkins and others do is only a metaphor.

Too often the metaphor takes over from the reality, and we end up with notions of "progress" in evolution - humanity is the pinnacle of life and the whole thing developed to generate us. I'm sorry, I think it was much more mundane and accidental than that, regardless of the wonders and horrors we can all see around us now.

Human (and most other multi-cellular) biology shows the result of at least two types of genetic development which must have merged in the past. The information power-house of the cell nucleus is where variety seems to develop - the inner-inner environment - but could it do so without the inner-outer environment within the cell wall which is at least in part constructed by the mitochondrial DNA?

Our cells are hybrids, and we can see how they might have developed from the merging of different kinds of organism. But I think I'd better stop now...

But then there are viruses...

An acquaintance of mine once propounded the view (commonly held?) that viruses are simpler than bacteria which are simpler than everything else, so viruses must have developed first.

But a virus needs a host in which to replicate, and it's a bit hard to believe that foot-and-mouth developed first, sat around waiting for cellular and then multi-cellular developments before it finally had an environment within which it could work.

That's a joke.

Viruses may have developed from "primitive" forms of "life" which might have been free-floating molecules, assemblies, mechanisms-in-waiting which only worked when they hit or merged with others. Many of the combinations would have been (self-)destructive. Some would have produced something else or worked to replicate themselves more frequently. This type of mechanism may survive in virus form.

Whether viruses are truly life or not is a matter of some debate, I was taught they were but Wumbeevil (who I believe is a biologist of some kind) argued that they were not classified as such - making archae and bacteria the simplest life forms.
His argument was that the biologists have defined life as needing to be able to self reproduce, have the ability to metabolise chemicals, perform respiration.... viruses can do none of this.

This is, however, just a matter of definition, philosophy looms near on this subject.

I have to say, that once again, Mund has put it very well.

I read somewhere that the evidence points to life starting only once - or at least the origin of life as we know it. Can't find the article now but as far as I remember, the evidence was in the genes of every life-form whose genes have ever been tested. They all contain traces of the original ur-gene. Forgive me - I find it hard enough to believe it started even once, never mind several times

I think a virus can actively seek out an environment. If a cold virus makes you sneeze, is that just coincidence or is it a "strategy" (is ploy a better word?) to get into another host. Even though they go with the flow when that's the only thing they can do, when an opportunity presents itself to get purposeful, they get purposeful. Or is that just the way it appears?

I think bacteria actively seek too. We may think of them as "simple", but really they're quite complicated. Not only are they able to change their chemistry to standby mode, but they can change their surface proteins to cause confusion and fend off attack and allow them to live in a variety of different environments or hosts. The spirochete that causes Lyme disease is able to defend itself against the immune responses of ticks, birds, deer, mice, humans and others, by changing its surface proteins. I don't suggest that this is anything beyond an automatic sort of response, but it's purposeful in the way our bodies try to fight off a cold even though we don't consciously plan a strategy to defeat the virus.

Your point about DNA being able to do no other than replicate if the conditions are right, seems pretty well key to the whole thing, once you get beyond the question of how on earth RNA and DNA came about in the first place. As Orcus mentioned, viruses are not always regarded as life because they can't reproduce without the machinery hijacked from the cells of a host. So perhaps the automatic tendency of DNA to replicate is more like the behaviour of crystals. But once the DNA is part of a more complex organism (the sort Wumbeevil would be happy to call "life") there is purpose - a sort of mindless striving for survival.

I agree with you completely about the notion of progress and humanity being some kind of pinnacle towards which all of evolution was aiming. It was a silly idea whose time has passed.

Not sure what point you're making about the mitochondrial DNA. Are you suggesting that they're evidence that life began more than once? I was under the impression that because it uses the same genetic language as the DNA in the rest of life and contains traces of the same ur-gene, it shares its origins with the rest of us. Sorry if I've misunderstood you there.

My turn to stop I think

I've heard arguments that there may have been several forms of early "life" with different replicators but that the DNA based replication won out and all others were extinct pretty early on. Who knows - hard to ever do anything but speculate on that one.

Not sure I agree that viruses have "purpose" or even bacteria (although you do get silia on bacteria that can give them motion).
That's an evolutionary pressure, there are zillions of viruses in us at once and its only the ones that are excreted some how (sneezing, coughing, faecal...) that can spread to a new host. This I think is what Mund was talking about when he mentioned that it was more accidental than anything else. It just so happens that those that are sneezed out survive, so the sneezed out viruses survive to replicate in a new host, those that don't die out, leaving only the ones that have however fortunatley found a survival route.

Bateria are clever little beasties, but compare that to our own immune system where most cells in our body can produce a different antibody to combat an invading organism - there are therefore millions of slightly different antibodies providing a good range of attacking species to make sure the invading organism is beaten off. Bacteria are able to change surface proteins and the like simply because they are so simple, they have no need to communicate with other cells asound them in the way those of a multicellular organism have to and so they have no need for the complex receptors and antigens on our cell surfaces which cannot be changed significantly without seriously compromising survival chances.

Hey, this is a forum. I like it

I mentioned mitochondrial DNA when I was starting to peter out. But the reason I mentioned it was to suggest that even the cells we are built from derive from a mixed inheritance - the mitochondria and various other bodies in the cell are likely to have come from the incorporation of bacterial mechanisms at some long-distant time.

ur-gene?

A gene is a pretty small sequence of DNA bases, and it's pretty obvious that mutations don't necessarily respect gene boundaries.

We can detect patterns and structures which may go back a long way. We can analyse genetic chemistry and see how little we differ from things like chimpanzees, or fruit flies... But this is just a statistical thing.

I'm not convinced that we can go down to the single gene level and find any evidence of the point in time at which the particular gene arose.

Hmm, the word ur is used in English, I didn´t know that. About the ur-gene, that doesn´t mean it only came from one source. Life can have originated in two different places, then intermingled creating that ur-gene and gone on from there. As long as it happened rather fast, so we don´t have any proper record of it. As far as I know about evolution in bigger animals the big steps doesn´t happen with mutations, but with intermingling. So maybe there was two simple forms of life, that got a boost when they intermingled. And a lot of other simple forms of life that never suceeded.

About wether the striving was there from the beginning. That is pretty much a matter of definitions. If you define life as something that has "striving", then life had striving when it started because it wasn´t life untill it strived. You see?

But about life happening in several places. We don´t necessarily have to go back several billion years to see life start. Maybe it happens often, but because the niches it should fill out are filled, it never gets anywhere. Somewhere in this world maybe there is life originating right now.

BTW What about beating entropy, isn´t that also a basic life-thing? To be able to absorb energy and use it to increase it´s complexity.

I've been rootling around trying to find the thing I read about the ur-gene. Couldn't find it. But I found something else that was interesting and kind of supports the idea that the commonality of our genes can be traced back a heck of a long way. Apparently the telomere (we were chatting about elsewhere Orcus) is the codon TTAGGG repeated over and over again, between 7,000 and 10,000 times in humans, at the end of each chromosome. Without going into what telomeres are for (because you probably all know), the same codon, with different numbers of repeats, is used for the same purpose in just about every life-form tested, including protozoans and fungi. It seems that, in the case of plants, the gene has an extra T. So even though, as you say Mund, genes may be small and mutations disrespectful, in the case of this particular bit of information, it's been copied with a high degree of fidelity since the last ancestor we had in common with fungi and protozoans. Doesn't that give you a warm glow?

I'm going to have to give the purposiveness of viruses and bacteria a bit more thought Orcus. I agree with what you said but I have a reservation that I'll need to explore before I can really discuss it properly. It's a very thought provoking subject, isn't it?

What do you mean about big evolutionary steps in bigger animals not happening by mutation but by intermingling, Xanatic?

Yes, I think life in some sense "strives" to survive and that's a fundamental quality of life. But this concept at the level of things like viruses is a bit fuzzy at the moment. I find it hard to imagine what form it could take in an organism that consists of no more that a strand of RNA or DNA in a protein capsule.

And yes, life knocks entropy into a cocked hat. Very interesting!

"The ur-gene" was what worried me - the idea that we could get back to a single, particular, original gene. I don't doubt that we can go back a long way and see what we have in common with the supposedly "humblest" of creatures.

The telomere is ancient, but a lot of things must have happened before it came into being. It is an example of a genetic control system which is so complex that perhaps it did only evolve once. Genes had to come into being which produced structures to control chemical processes coded for by other genes.

It may not be exactly the beginning of life, but the evolution of "the genetic system", of which there is a small number of variants must be considered a pretty basic step. (Correct me if I'm wrong here - are there any significantly different genetic systems left? Those strange creatures found in a lightless sulphur-rich scum in an eastern-European cave?)

It's those words again - striving this time. I tend towards the chemical-deterministic "selfish gene" position, which is that organisms do what they do because they have genes which predispose them to do it.

A simple form of life (?) such as a virus can basically do only two things - wait for a suitable environment and replicate when it encounters one. Mutation of the virus will either change the attributes of the environment that is suitable (that it is "waiting for") or change the side-effects of its replication in that environment (usually some illness). Some changes to the suitable environment will result in the extinction of that mutated strain because that environment is never encountered.

A bacterium may "learn" new chemistry or new behaviour, but only by mutation. To ingest and process a new molecule from the environment it has to develop a different gene (or several). To move towards warmth, likewise. To be able to stand the temperatures in hot springs etc, likewise in spades.

Is it fair to say that any behaviour classed as "instinctive" must be controlled solely by the genes? I suspect it's a circular definitional point.

Some organisms have developed genomes which enable them to learn from their interactions with their environments. Another circular definition - nothing which is learned will be incorporated in the genome for subsequent generations: anything which is so incorporated was not learned.

A subset of the learners have developed genomes which enable them to learn from example - to be taught.