Discussion in 'Biology & Genetics' started by paddoboy, Jun 1, 2015.
If that is correct, seems unlikely it was a "random" event...
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Bacteria can reproduce every few hours. Simple molecules would be reproducing every few seconds. I think evolution is a lot slower than it used to be. There is also a tendency to see the process as serial but it's more likely there were a myriad self-organising systems which could interact.
Human influence on the environment is causing it to change much faster than natural influences would, so if anything, evolution should be faster now than it was before Human civilization took off.
Just look at the influence the industrial revolution had on the evolution of the Peppered Moth.
I think spandrel is alluding simply to evolution requiring successive generations as part of its process, and that the closer you get toward the earliest life, the faster that average replication across "life" as a whole (so spandrel is saying).
I don't think spandrel was trying to compare the rate of evolution we have now with the rate pre industrial revolution or of the rate pre-humans etc, but in the orders-of-magnitude difference between, say, now and back when the average rate of replication for all "life" on earth (as it was all just starting) would have been very short (per spandrel).
We may have increased the rate of evolution in some animals, but quite possibly slowed down the evolution of others - through hunting, domestication etc.
But humans are just one environmental change, and life goes through many. I guess this issue depends on how you define the "rate of evolution" for life as a whole, as life surely evolves all the time. Do we go by the number of new species emerging, for example? I don't know.
Why do so many people find it so hard to accept that life arose from the geophysical and chemical processes which arose naturally out of the energy and natural organization of matter imparted to Earth from the accretion disk that formed it? ( I mean other than religious superstition...)
I do like esp. the last part of your remark, esp. the word "systems". When some "thing" combines with some other "thing" (as in chemical bonding) the newer "thing" takes on a new "life". And this introduces the concept of "systems", something poorly understood in most of these threads, and rarely discussed, as it should be. A hydrogen gas "system" is highly explosive in oxygen, and an oxygen gas "system" is highly reactive with just about all chemicals that formed the minerals and atmosphere. And just about everybody here should agree that when hydrogen associates with oxygen, the most likely outcome is a water "system". (Take for example, hydraulics which deals with the bulk system of water extensively).
But one of the properties of the water chemical "systems" is that it is not perfectly "stable" - it dissociates into H+ and OH- to some small degree. Further, this is a cyclic process. Further, in an open container in the air at STP, there is a pumping action that takes place, exchanging water vapor evolving from the container with water vapor in the air colliding with the surface of the water.
Water is not dead! Gee I proved the origin of life! Chemicals!
Seriously, the system view is the only real way to look at problems of chemical and biological complexity. Integrating smaller pieces of "stuff" together, as in the natural formation of molecules found in common minerals, completely changes the behavior (usually) expected from the constituent molecules or atoms. Furthermore, these systems are (and were) exposed to the systemic actions of other systems - atmosphere and weather, water, interaction with other minerals, and all energy sources whether from these or solar or geothermal sources.
Put it all together and I think someday there will be a complete catalog of all of this systems and systemic behaviors, for us to point to as the "forms of life" that preceded "self-replicating / protein and lipid-building" forms.
(All that from your mention of the word "system". But I have been accused of being a little manic at times.)
Hey folks here is the text of the paper in question (I think):
Sorry if I didn't explain myself very well Daecon, I was using evolution in it's broadest sense. A set of chemical reactions can occur in milliseconds or seconds. Any robust enough self-reproducing system could undergo evolution in hours or days rather than thousands of years, and we all know the power of selection. It wouldn't take long for highly complex interconnected processes to take over, a few years? I should think loads of such thingies would be arising and disappearing until the form we know as life won out.
Having said that I see that NASA has discovered an enterprising bacteria in California which uses arsenic instead of phosphorus. In some ways life has become quite conservative in the last 3 billion years.
Ah, yes. I see that now.
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Moon , Venus, Mercury and others. They have chemicals, there is water in ice caps on Mars , Is there life ?
My point is that, depending on how we define "life" (esp. at the dawn of living cells), we will note that raw chemicals meet all or most of our definition.
Is the sum greater than its parts? Yes, when we treat a collection of smaller pieces, integrated together, as a system, then it's possible this system takes on a new "life". It certainly can behave differently. Hydrogen, set apart from all other chemicals, and devoid of any stimulus, comes to a standstill, so to speak. But when clumped together as in nebulae, it tends to form huge stellar accretion disks that give birth to new stars. The hydrogen system, so to speak, "comes to life" and it does so "spontaneously". It is not even "deterministic", but rather, the outcome of something that we associate with some ill-defined probability distribution.
One may argue that "raw chemicals can't replicate themselves". Nonsense. In a glass of water, the molecules are constantly dissociating (dying) and the ions produced randomly recombine (are born). A second cycle takes place between the liquid molecules at the surface, which, when struck by randomly arriving water vapor molecules, will themselves vaporize, only to be replaced by water vapor molecules condensing out of the air. A scarier example is the way free chlorine molecules (which have found their way to the ozone layer) will react with ozone - breaking it down - and then at that stage a new chlorine molecule is "born". This is essentially what most catalysts do. True replication is a little different, however, this decomposition of ozone kind of resembles the building of something else (like a protein) from an organelle (ribosome), at least functionally (the result is similar; the rest is quite different).
But let me try to get folks here to look at this from even a different angle. Suppose we could look inside a cell, and see its working parts - the organelles, the "soup" of free molecules dissolved into the plasma, and the other cell structures that make all kinds of cellular activity possible. To visualize this, brilliant people have come up with some fascinating renderings:
These chemicals certainly look "alive" don't they?
Molecules are obviously alive. How can life come from something that is not, at least to a certain extent, alive? The only difference is that cells are more evolved forms of life than molecules.
I wouldn't be surprised if we found tardigrades on Mars by the end of the decade.
NASA expected to reveal evidence for liquid water on Mars at ‘major science finding’ announcement
If that is the premise on which your argument is based, can you justify that premise?
What is it about molecules that makes them "obviously" alive?
O don't know what you mean molecules are alife. I have a bag os Na2CO3 that is not a life, you probable have sugar ( Glucose ) which can isomerize into fructose . Moller made some amino acids in the 1950 they have not changed. If you make some compounds under certain condition , than if you change the condition you will change th compound.
It is a beautiful picture and show. I think the word random does not fit well. Every chemical structure have a purpose to function for the survival of the cell. I think also there is also some difference from single cell to cells of a living animal, were we should not extrapolate lightly.
An amoeba, for instance, is a single cell animal, so there is no need to extrapolate.
How can a mountain come from something that is not, at least to a certain extent, a mountain? Seems like a silly question.
Matter has the potential to become a mountain or to become life. Its natural properties can manifest in various ways, depending on the conditions. That's no reason to say that matter "is" alive.
"Random" is a term that easily leads to confusion. "Unpredictable", "disorganized" and "chaotic" come to mind. But of course in science it has a pretty well understood meaning. The "Normal Distribution" ("Bell Curve") is so-called because, as we observe, so many natural processes do follow the Gaussian Distribution (its technical name.) In the cell, one of the main kinds of random behavior which is so influential (and without which life as we know it could not exist) is the so-called "Brownian Motion", which is the random collision of molecules (in the cytoplasm) into one another.
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Looks alive to me. At lively. Maybe life-like. These are just molecules colliding in a confined space.
This is the actual transport mechanism that makes possible the assembly of structures within a cell as illustrated in the animation. This is how nutrients make their way to the ribosomes, for assembly into proteins, for example. Indeed, the organelles of cells have specific functions that give the cell its life. But my question is: are the organelles themselves alive? The customary answer is "no". But look again at the video and you begin to wonder what we mean by "life".
Our usual idea of "life" applies to the way we understand the way large plants and animals interact with the world. Obviously this is easily "interpolated" to the way we imagine cells are "alive", even though we need microscopes to see them. The sperm cell is "alive" as is the egg, but at their union only one "living" mass remains. Yet neither parent cell actually "died". We can certainly agree that the embryo is a living organism, although its "life" is ephemeral. In effect, it is a factory of tightly packed genetic sequences which begin to "unfold", and in this regard it has no specific phenotype, other than the ones we recognize as "stages" of something called "embryonic development". In insects, we observe metamorphosis, and readily acknowledge the life of each, but that life (egg to larva, or pupa, or adult) in some regards has little common ground. This same process can be observed in other organisms (crustaceans, hydra, etc.) Did the insect "die" and "resurrect" each time? Of course not, but metamorphosis, as in embryonic development, as in fertilization, or as in the interaction between organelles and the objects they collide with in the cytoplasm (RNA, nutrients, other organelles..) a system effect is taking place. If it is merely the interaction of molecules then we have little dispute that it's merely a chemical reaction. However, molecules organized into larger structures (e.g. organelles) behave in more functional way - they dissolve and replicate structures, for example, they extract energy and they perform signalling, etc. Is it this functional behavior that gives a reason to draw the line and say "It's ALIVE!" (here recalling Frankenstein).
I say, no, the conventional meaning of life is sort of arbitrary. In some regards it is a holdover from ancient superstitions. I am not actually taking issue with the word or its conventional meaning. It's just that I think it's pretty ridiculous to try to draw strict technical boundaries about what it means to "be alive" in reference to the earliest forms of cells on Earth, and their lowest common ancestor (such as something not truly alive, yet chemically "ready" to spawn "the first living cell" as it were).
But of course that idea becomes insanely twisted as soon as Creationism enters the discussion. Having long ago shed the shackles of religious superstition, science has for a long time tried to grapple with this question on its own merit, and to try to understand how "best evidence" ties together the facts, without watering down our objectivity (with the subjectivity of religion).
So we are left to decide what "life" means at the primordial moment that it emerged. Once some kind of nucleus became viable, (and that's the operative word here) as a chemical catalyst for the replication of molecules needed for cell reproduction, then - as we understand it - the stage was set for populating the Earth. I think that part is the more interesting one: what was the chemistry of primordial Earth? How did various energy sources drive primordial cells in a certain evolutionary direction? How was the Earth "terraformed" so to speak by these first evolutionary pressures of the niche? How did competition for resources, or depletion thereof, affect primordial cell evolution? How many ways does mutation occur, how are some mutations made likely (to within some small percentage) in primordial cells?
I guess in summary to the question of how abiogenesis strictly took place, I would just say: who cares? It happened however it happened, except in recent decades we have had the benefit of finding out how it probably happened. Other than that, science marches on, collecting data, analyzing it and forming best conclusions, and continuing to move closer to a way of explaining this in substantial detail.
Everyone does it - I do it - but one of the worst ways to approach this is to speculate. Yes, amino acids may have rained from the sky, and yes, they may have formed naturally on Earth by other mechanisms. Both ideas are very remote (far removed in time from the raw data) theories (explanations) which can not yet be definitively ruled out. But in any sane discussion of this, we must assert that living cells did not arise out of processes the violate the laws of nature. Nor would we turn to the highly speculative or superstitious explanations, and assert sweeping conclusions like "meteor proves God created the world in 7 days" by the cursory treatment given by Creationists to the body of science that already exists, and which is expanding daily. Not that or any other nutty claim.
Someone mention tardigrades?
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This is a lot of writing . I think you are a disciple of Dawkins . so I would not be surprised you copied some of his lines . that is ok.
I dont' believe all chemical reaction are random collision , I agree there brownian motion play a roll, but ionic affinity concentration, polarisation in the system have an influence on product formation.
Perhaps in a Prokaryotic the random reaction may play a larger roll by I doubt in a Karyotic cells random reaction will function .
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