Biological evolution - prebiotic chemistry, biogenesis, evoluti

dickbill · 2003-10-13 10:29:45

Hi all, are you interested to discuss this thread, with a focus on Evolution ?

Shortly, I will sumarise the different theories of Evolution:

Creationism, the oldest "theory". God created all living species, etc, it's not really an evolutionary theory nor a theory, but as to be mentioned, "by Law".

Darwinism, a non deterministic theory. Only involves hereditary variations (mutations, polymorphism etc) and selection. There are many variations of neoDarwinism: punctuated equilibrium of Gould ( a rather powerfull explanation IMO which eliminates the gradualism weakness of darwinism), neutral mutations of Kimura, the selfish gene theory of Dawkins etc.

Lamarckism, a non deterministic theory, but not quite supported by the facts in its oldest form; Lamarck's theory involves cumulated hereditary variations that are transmitted to the offsprings (they are not....hmmmm, are they really not ?)

An anti-darwinism movement, the Evolution with Design movement, based on many difficulties of the Darwinian theory: such as the problem of the "intermediates" (intermediates forms in an evolutionary serie cannot be optimized, but then they should be negatively selected according to Darwin's theory), there is also a notion of macroevolution versus speciation, the lack of intermediates in the fossil record, the impossibility of gradualism in certain cases etc.

My opinion is that even if the old Lamarck proposition is not supported by the fact, it should be reintegrated in the neodarwinism because genomes can run with a quasi-lamarck behavior. Genomes are sensitive to environmental changes. Genomes reacts to environmental changes and Environmental changes can induce genetic variations in their turn.

Bill White · 2003-10-13 10:47:47

My lay person's grasp of evolution has been strongly influenced by William Calvin. A sample quote follows:

The six essentials aren't a settled issue. What I was aiming for, however, were the essential ingredients of an algorithmic quality-improvement process20, stated in a way that didn't impose a lot of biological preconditions. I wanted, for example, to avoid making use of the genotype-phenotype21 distinction, or a universal translation table like the genetic code; I wanted to describe a process, not make an analogy. John Holland's computational technique10 known as the "genetic algorithm" comes close to what I had in mind, but Holland was trying to mimic recombination genetics in a computational procedure for discovering solutions, and I wanted to abstract more general principles that avoided the presumption of recombination.
Since many of us think that (properly defined) the Darwinian process is a major law of the universe, right up there with chemical bonds as a prime generator of interesting combinations that discover stratified stabilities, we want it to be able to run on different substrates, each with their own distinctive properties that may, or may not, correspond to those seen elsewhere. So our abstraction should fit the species evolution problem, as well as the immune response, but also be independent of media and time scale. Here, paraphrased from The Cerebral Code, is what I ended up with:

Evolution is => merely <= an algorithm which allows information to bootstrap or ratchet itself into increasing complex patterns. Darwinism is really mathematics.

Evolution operates within an system of information and biological evolution uses DNA/RNA as merely one potential media or substrate. Richard Dawkins has crowed that DNA/RNA heredity and evolution is not only mechanistic, it is also digital as opposed to analog.

This ratchet allows increasing complexity notwithstanding the general trend towards entropy.

The genotype/phenotype distinctions and the wrongness of Lamarck are factual observations about DNA/RNA evolution however in other evolutionary substrates or media those "facts" may not remain true and therefore are not essential features of Darwinism.

Adrian Hon is the fellow I most wish to hear from on this subject.

clark · 2003-10-13 10:47:51

If we accept evolution as the basis of biological development, and creationism as the spontaneous development of biological organisms, how did life begin?

Didn't life just sort of appear, or did it all evolve from mutated chemical reactions from inorganic molecules?

Why would chemical reactions form into more complex forms? What process would make inorganic chemicals evolve in the first place?

clark · 2003-10-13 10:52:45

Evolution can operate within an system of information and biological evolution uses DNA/RNA as merely one potential media or substrate. Richard Dawkins has crowed that DNA/RNA heredity and evolution is not only mechanistic, it is also digital as opposed to analog.

Hmmm... sounds interesting Bill. Wouldn't this imply that everything is merely an evolved form of the original 'nothing', developing various complex forms that are stable enough to exsist? Or am I waaaaaaay off? :laugh:

Entropy= reset button?

Bill White · 2003-10-13 11:41:53

Evolution can operate within an system of information and biological evolution uses DNA/RNA as merely one potential media or substrate. Richard Dawkins has crowed that DNA/RNA heredity and evolution is not only mechanistic, it is also digital as opposed to analog.
Hmmm... sounds interesting Bill. Wouldn't this imply that everything is merely an evolved form of the original 'nothing', developing various complex forms that are stable enough to exsist? Or am I waaaaaaay off? :laugh:
Entropy= reset button?

My understanding of the current scientific theory is that life got started when some longer chained organic molecules (someone here calls them CHONs - thank you for that!) found a way to imprint themselves on the organic chemistry soup they were swiming in and thus replicated themselves.

I am reminded of Kurt Vonnegut's "ice-nine" whenever I think about this. Crystals can imprint themselves on their surroundings as well.

Whether this was on Earth or elsewhere (pan-spermia?) is ultimately irrelevant. Some-where, some-when long ago, some CHON molecules accidentally discovered the ability to copy themselves. Then, using the algorithms described by William Calvin, increasing complexity was bootstrapped in the face of entropy - - the evolutionary rachet. Today, the human brain contains more coded information (as a function of weight) than any other known material in the universe.

"Everything" is the evolved form of whatever stuff the original pre-Big Bang singularity was made out of. And whatever rules (cosmological constants) governed how this "stuff' interacted. The stuff is way less important than the rules, IMHO.

After the Big Bang the most complex stuff was helium.

Eventually, supernovas fashioned the larger elements, carbon, nitrogen, iron, etc. . .

Next, CHON molecules were created at random and so on until we end up with William Calvin, the smartest man in Seattle.

This is my amateur, thumbnail, grasp of these issues. Its all IMHO, as always.

Of course, there is Mark's opinion. "In the beginning there was the Word" (Logos) which is a poetical way of saying much the same thing.

dickbill · 2003-10-13 12:05:56

If we accept evolution as the basis of biological development, and creationism as the spontaneous development of biological organisms, how did life begin?
Didn't life just sort of appear, or did it all evolve from mutated chemical reactions from inorganic molecules?

In the pure darwinian sense, it's correct to say that Life didn't appear. There is no life, just an accumulation of dead atoms into complex pattern. The issues of "what is life" is crucial here. You can see by yourself how confuse the issue can be:

We, as an individual and body and mind, define ourself as alive, and our organs are also alives and relatively independant of our body, because we can transplant hearts and kidneys for exmple. The cells in our organs are also alive, they could be isolated and grow by themself. The unicellular paramecia is "obviously" alive and a single bacteria is alive. What about the nucleus and the small organites in our cells ? this is less obvious. What about the DNA molecules, are they alive ? What about the atoms which constitute the DNA, here we are sure that thay are dead, as dead as the same atoms in the dust.
So there is a continuum here, but at one moment we cannot say precisely if the thing is alive or not. A virus for example, alone it is just an agglomerate of dead atoms, and the virus itself is pretty dead if left alone, you could as well give its chemical composition in carbon, oxygen, nitrogen etc. Inside the cell that it is parasiting however, no doubt that the virus is alive.
So an isolated virus is a dead thing while a virus in the ensemble (virus + cell) is alive. I could say the same for a DNA or RNA molecule.
So maybe the whole life kingdom and evolution is just an artifact: there is no life, just dead matter and atoms organized into more and more complex pattern. The fuzzy threshold between "obviously inanimate" and "obviously alive" would be in the complex organic molecules that can carry information. Then the problem of origin of life is resolved: there is no "quantum leap" between inanimate and alive and there is no origin of life.
That's the darwinian position, purely mecanistic and atheistic. Life is an artifactual point of view, "complexity" is the real thing, and complexity is a purely natural phenomena which can arise spontaneously.

But the truth is that : we don't know. Is there a special state of the matter called "life" (or mind) ? and If yes, what is the physical definition of this state of the matter.

Why would chemical reactions form into more complex forms? What process would make inorganic chemicals evolve in the first place?

I think complexity is possible because it generates more entropy than non complex system. Remember previous discussions with Schrodinger, living things "feed upon" negantropy by getting rid off the flux of entropy that they generate. So "complexity" obeys the laws of thermodynamic.

In the case of carbon chemistry, this is a case of anthropic principle here: the level of energy in the atom carbon is just at the right level to allow complex molecular bonds and organic chemistry. This is just "luck" supposedly and indeed a pure darwinian concept: if the level of energy of the carbon were different, then we couldn't talk about it, we would not be. That's natural selection.

clark · 2003-10-13 12:54:56

There is no life, just an accumulation of dead atoms into complex pattern.

So there is just 'awareness'?

You point out that complex lifeforms are based on the interactions of simpler life- my organs are alive, as I am alive, and my organs are alive becuase of the individual cells that make up that organ are alive, and on and on, until we get to the atom... which isn't alive. How do we arrive at this conclusion that atoms are not alive?

So maybe the whole life kingdom and evolution is just an artifact: there is no life, just dead matter and atoms organized into more and more complex pattern.

Well, a table is a complex pattern. So is a rock. But this premise goes against the principle that the universe is breaking down, not constructing...

Why would the universe develop more complex systems?

Or is merely that if it didn't, then we wouldn't be having this conversation? :laugh:

In an infinite universe of infinitine possibilities, eventually, a universe that may exsist, will eventually exsist, given enough time, which is infinite, which means the creation of a complex universe able to comprehend itself is eventual.

Awareness is the eventual result of infinity?

dickbill · 2003-10-13 13:09:31

But now, on the difficulties of Darwinism.

One is the problem of the missing intermediates in the fossil record. The guys who initially worked on the concept of Evolution, Darwin, Lamarck, Cuvier, worked on real organisms AND fossils.
One of their big proposition is that we have common ancestors that have primitive characters. We acquired modern characters from these primitive one, through gradual small modifications over eons.
For example, mammals are believed to have a common ancestor in a specific branch of primitive reptiles. Modern Humans must have a common ancestor with modern higher primates. Of course these ancestors died, but where are their fossils ? The fact is that very often, paleontologists don't find the "common ancestors". Instead they find the new species already and definitively formed.
Steven J Gould resolved the issue, I think, with his theory of punctuated equilibrium. In short, for him there is no gradual evolution, rather evolution works in jump followed by long periods of stasis. The "jump" itself are very short in duration, in geological scale, and the number of organisms who did jump (the true common ancestors) are too few to have a chance to have their bodies fossilized and found by paleotonlogists.

Another problem is the inadaptation of the intermediates. The inner ear bones of the mammals come from primitive jaw bones and branchial arch of primitive reptiles. These primitive reptiles couldn't hear with ears since they didn't have ears, their jaw must be in contact with the ground to feel the vibration and "listen". But they were well adapted since they could feel the "sounds" with no ears and even if the mammalian system is more performant. Now the jaw bones of these reptiles must migrate and form the bones of inner mammalian ear. Very well, but this must include some steps, during these steps, the "intermediate" forms have lost partly the reptilian type hearing system, and havn't fully acquired the ultraperformant mammalian hearing system, yet. In short, they must be deaf or with poor hearing. According to Darwin, they must be counterselected by the natural selection and so cannot give any offsprings. They are just inadapted monsters. Here, the modern answer is less clear and less convincing than with Gould : it could be by accumulation of small quasi-NEUTRAL changes that the transition reptilian ear/mammalian ear took place. At each small step, the inadapted "monster" actually retains a little bit of hearing, enough to survive, until it reachs a mammalian configuration. However, here, without a little bit of Lamarckism, that explanation falls short. Do you see why ?

clark · 2003-10-13 13:25:38

Hmmm...

But couldn't the same results occur gradually by placing an emphasis through predatory behavior as the driver of evolution?

No lizards can hear- eventualy another organism develops to eat lizards that can't hear. Millions of years of this results in lizards surviving based on being able to hear ever so slightly, so they can avoid the organism that eats lizard who can't hear.

gradual improvements only occur in large gene-pools due to the dilution of ressecive genes and the randomization of dominant genes among the overall breeding group. Major changes may occur at a faster rate in smaller gene-pools due to the re-occurance of ressive genes being able to gain dominance. This in turn causes what appears to be faster mutation, but it's just the expression of recessive genes that are more pronounced due to the limited gene pool and lack of dominant able genes.

So imagine that these lizards can't hear- the organisms eat them, and get good at eating them after millions of years. Eventually, the gene pool shrinks, thus magnifying the effect of the reccessive genes (which might have contained a gene for hearing).

Just a thought, probably wrong.

clark · 2003-10-13 13:57:52

Very well, but this must include some steps, during these steps, the "intermediate" forms have lost partly the reptilian type hearing system, and havn't fully acquired the ultraperformant mammalian hearing system, yet. In short, they must be deaf or with poor hearing. According to Darwin, they must be counterselected by the natural selection and so cannot give any offsprings. They are just inadapted monsters. Here, the modern answer is less clear and less convincing than with Gould : it could be by accumulation of small quasi-NEUTRAL changes that the transition reptilian ear/mammalian ear took place. At each small step, the inadapted "monster" actually retains a little bit of hearing, enough to survive, until it reachs a mammalian configuration. However, here, without a little bit of Lamarckism, that explanation falls short. Do you see why ?

Couldn't they develop both in parrellel? Why must one fail, while another succeeds? So they still retain the reptilian hearing, and over time, develop the mamillian one as well (two hearing organs now). As the mamillian hearing improves, THEN the lizard one grows unused, it then begins to wither away, leaving only the stronger hearing (or most competitive) organ.

Amphibans are a good example- they carry the neccessary equipment to breath on land and on air- wouldn't this be an 'intermediate' step between the sea and land world for organisms?

dickbill · 2003-10-13 15:08:19

Clark, I want to answer you former post, "how do we define that an atom is not alive". What I said is that an atom of iron, taken alone, is the same in a mineral or in a hemoglobin molecule. There is a difference only when we consider the mecanism by which this atom came in the molecule or the mineral. In the molecule it involves an information treatment, but the iron atom per se is the same. So if it is dead in a mineral, it must also be dead in a big, complex hemoglobin molecule. You can extend this to the whole hemoglobin molecule, by itself it's a molecule, like the glucose C6H12O6, nothing more, unable of autoreproduction. However, the situation is different for another big complex molecule: the DNA or even better, the RNA (a nucleic acid similar to the more famous DNA, but which for some reason is ignored by the media). This RNA molecule, by itself, can be autoreplicative. My point is that we could be tempted to call this autoreplicative RNA "alive" molecule by virtue of this replicative quality and by doing this, we would define a new state of the matter filled by some "Vital fluid". Or we could notice that the RNA is just an ensemble of dead atoms and just call it a "complex organic molecule", denying the "alive" quality.

But couldn't the same results occur gradually by placing an emphasis through predatory behavior as the driver of evolution?

Sure, you can also include into the Darwinian "natural selection", and its genetic derivative the "pressure of selection" the sexual selection, but general fitness with respect to the environment includes all that.

No lizards can hear- eventualy another organism develops to eat lizards that can't hear. Millions of years of this results in lizards surviving based on being able to hear ever so slightly, so they can avoid the organism that eats lizard who can't hear.

You can always find a specific situation where the "misfits" find a ecological niche (nest ?) and won't be eliminated under Darwin's law. But it is not Darwinism then.

gradual improvements only occur in large gene-pools due to the dilution of ressecive genes and the randomization of dominant genes among the overall breeding group. Major changes may occur at a faster rate in smaller gene-pools due to the re-occurance of ressive genes being able to gain dominance. This in turn causes what appears to be faster mutation, but it's just the expression of recessive genes that are more pronounced due to the limited gene pool and lack of dominant able genes.

This is all true, but it is a population genetic issue, based on allelic and polymorphism variation. It is called speciation, or specialization inside the same species (the famous textbook example of the white or black moth)
Evolution is more about a serie of species, like the hominids, the equide, from the ancestor form to the final form. If you always invoke the "pressure of selection and random mutations" as the motor of evolution, then the problem of the inadapted, misfit intermediates, remains. If you remove the "pressure of selection" drive, then it is worst, because the variations/mutations under darwin's law become an erratic processus and you would never get a serie of oriented mutations cumulating to transform a jaw bone into an ear bone.
These bones were originally part of the branchial archs of the fish. I cannot imagine how they could end up in the jaw of primitive mammalian reptiles and later in the mammal ear without selective pressure IF the mutations are random. Selection is the only thing which give some directionality to the evolutionary process in Darwin's theory. However, if there is selective pressure, Darwin doesn't explain very well how the intermediate can survive with an handicap that they must have.
This is a weakness in Darwin's theory of random fluctuations sieved by the natural selection pressure.

dickbill · 2003-10-13 15:42:27

Couldn't they develop both in parrellel? Why must one fail, while another succeeds? So they still retain the reptilian hearing, and over time, develop the mamillian one as well (two hearing organs now). As the mamillian hearing improves, THEN the lizard one grows unused, it then begins to wither away, leaving only the stronger hearing (or most competitive) organ.
Amphibans are a good example- they carry the neccessary equipment to breath on land and on air- wouldn't this be an 'intermediate' step between the sea and land world for organisms?

It must be something like that, double redundant system, which allows one to stay functional or partly functional while the other is still in process. Everything happens as if those "misfit" were submitted to a reduced selective pressure.

The drawback of that is : where do you get the evolutionary trend under reduced pressure ? Since the system is partly redundant, the reptile can hear a little bit and can survive and reproduce, fine. But this reptile is still far to have a full mamalian ear. More steps are needed to move the bones further, reduce their size etc. Darwin works with random mutation and under darwin's law, the offspring of the missfit can have another random mutation which might well put back the bones in their original reptilian position or to a completely inadapted position. Why would they care since they can survive thanks to the old redundant reptilian system ?
But I agree that the bones could also move and change their shape to make, by chance, an inner ear of mammalian type.

However you see that to do that you need :
1) a redundant backup system
2) 2 or 3 more steps of mutations in the "right" direction

That's possible with enough time and a large population, but then it doesn't fit well into the Gould theory of fast changes.

dickbill · 2003-10-13 16:52:15

I think it would be a little bit easyer to climb a hard evolutionary slope such as the reptilian/mammalian ear transition, if a little bit of lamarckism was reintroduced into the pure Darwinian evolutionary process.

Lamarck original idea is that organisms, when they use intensively an organ, develop that organ into a more powerful one and that this improvment is transmitted to the offspring. Strictly speaking this is not true, you can train all your life to be a fast runner and get powerful leg muscles, your children won't be born with more powerful than average legs. However, being an accomplished runner yourself, you might find natural to train your children to run as well. And by chance, if some of the offspring possess a natural biological facility to run, such as a small metabolic advantages or mutation, this facility will be amplified by the transmitted behavior. It is like a weak selective pressure is increased here to create a stronger evolutionary trend towads a fast runner specy.
Such lamarckian behavior would push individuals with a small neutral difference or even slightly unadapted individuals, to put themself under the grip of the natural selection (a positive grip if possible). Under Lamarck's law, what you do matters, you are partly the master of the evolutionary trend that you and your offspring decide to follow.
Under Darwin or Gould, you are submitted to random movement and you have no control on your evolutionary path. Anyway, there is NO path, this is the basic of Darwin, or Gould. With a small variation such as described above, (small, neutral or slightly disadvantagous), the "natural selection" has no grip on you, you might survive or not, that's pure random and your offspring will be submitted to the same blind random process. It is doubtfull that under such circumstances, you will "decide" to take any evolutionary pathway.

So through transmitted behavior, but maybe not only trough behavior, the theory of Lamarck could make a come back.

dickbill · 2003-10-13 17:13:01

So through transmitted behavior, but maybe not only trough behavior, the theory of Lamarck could make a come back.

And as a consequence, a lamarckian evolutionary trend is not equal for all organisms, in involves transmission of something: information or behavior, while darwinism does not. Then, the more primitive the organism, uncapable to hold information, the more to a random Darwinian force it is submitted, the more complex the organism, able to process information, the more Lamarckian becomes its evolutionary path.
Higher organisms, including humans, might only be under control of a Lamarckian trend. The part of darwinian evolution in humankind might be negligeable now.

A direct application is Mars : some part of humankind want to go to Mars, why ? maybe these guys feel that the natural selection will have a favorable grip on them there. On them or on their offspring meaning that a new evolutionary trend is virtually created and transmitted. Indeed, Martians might well reactivate the hominidization process that ended up on Earth with fast food and the bachelorette and constitute the only branch of humankind that will evolute and survive. That's a good reason to go to Mars I believe.

dicktice · 2003-10-13 17:41:44

We escape from Earth, to survive elsewhere out there in some place of our own making: That's an evolutionary process, surely.

Palomar · 2003-10-13 18:08:47

*Is carbon-14 dating considered legitimate?

I read (years ago) some material denouncing it as a severely flawed method.

I can't recall the example precisely, but apparently a certain species of mollusk was supposedly extinct by hundreds of thousands of years (according to the carbon 14 data)...and yet the specimen for the carbon dating was still alive (!). But I'm not certain of the legitimacy of the source which reportedly that supposedly greatly-flawed test (was an anti-evolution/pro-creation source).

--Cindy

dickbill · 2003-10-13 19:48:46

*Is carbon-14 dating considered legitimate?
I read (years ago) some material denouncing it as a severely flawed method.
I can't recall the example precisely, but apparently a certain species of mollusk was supposedly extinct by hundreds of thousands of years (according to the carbon 14 data)...and yet the specimen for the carbon dating was still alive (!). But I'm not certain of the legitimacy of the source which reportedly that supposedly greatly-flawed test (was an anti-evolution/pro-creation source).
--Cindy

I think the method is safe, but it infers that the radioactivity comes from the carbon ingered and is contaminant free and that is difficult to know. In the case of the holy shroud of Turin, supposedly representing a picture of the Christ, ages from 1000 to 2000 years old have been given. depending of what piece of tissue, different ages were obtained. Contaminant might be modern pollen, modern pieces of tissue added, dust etc. Every modern thing containing Carbon14 was a contaminant .
I don't know the specific story of the mollusk you quoted, Cindy, but it seems more like a story of a living fossils, like the fish Coelacanth , from time to time species supposedly extinct are discovered alive.

"Radioactive carbon, produced when nitrogen 14 is bombarded by cosmic rays in the atmosphere, drifts down to earth and is absorbed from the air by plants. Animals eat the plants and take C14 into their bodies. Humans in turn take carbon 14 into their bodies by eating both plants and animals. When a living organism dies, it stops absorbing C14 and the C14 that is already in the object begins to disintegrate. Scientists can use this fact to measure how much C14 has disintegrated and how much is left in the object. Carbon 14 decays at a slow but steady rate and reverts to nitrogen 14. The rate at which Carbon decays (Half-life) is known: C14 has a half-life of 5730 years. Basically this means that half of the original amount of C14 in organic matter will have disintegrated 5730 years after the organisms death; half of the remaining C14 will have disintegrated after another 5730 years and so forth. After about 50,000 years, the amount of C14 remaining will be so small that the fossil can't be dated reliably.

~Eternal~ · 2003-10-13 21:58:59

I am Christian myself and find physical evolution a theory simply based on linear thought.
Human life was created by a higher being wether
you believe it was a Supreme Being, Alien, or another universe.
The evidence is all their, you just have to look for it.

Shaun Barrett · 2003-10-14 06:41:18

http://newmars.com/forums/edit.php?id=20536Well, it won't matter much to the males here in about another 5000 generations. Apparently, we guys (or blokes) will have to leave such discussions to the women.
According to a researcher somewhere, the human male Y-chromosome is 'damaged goods' and is becoming more and more decrepit as the generations pass. By about 125,000 years from now, male fertility will be about 1% of present values and the human male will be no more.
Fortunately for the human race, it is possible, even today, to combine the genetic material from two female gametes (or eggs) to create a new individual .. female, of course! So, humanity will go on but in a different form - Homo Shopiens Retailiens!!

There'll be no more war, baseball, football, or toolsheds. Earth will be terraformed to make the sky pink and O'Neill colonies will consist almost entirely of shopping malls, some over twenty kilometres long!
There'll be no more fathers, grandfathers, brothers, uncles or sons and the meaning of the term 'female' will be academic. There'll just be people.

So much for "It's a man's world". Make the most of it while the going's good, fellas!!
:laugh:

Byron · 2003-10-14 07:10:24

According to a researcher somewhere, the human male Y-chromosome is 'damaged goods' and is becoming more and more decrepit as the generations pass. By about 125,000 years from now, male fertility will be about 1% of present values and the human male will be no more.

I think that "researcher" needs to get his head examined...

I seriously, seriously doubt that "nature" would allow males to become extinct...when has this ever happened to a mammalian species?

Admittedly, it is widely known the the male chromosome is "damaged goods"...but women concieve more male embryos than female to make up the difference...and the process of natural selection will always insure that "male viable" children will make it to adulthood to have healthy male offspring.

I think us males can sit back and breathe easy...we'll be around for some time yet!....

B

Palomar · 2003-10-14 07:20:26

Well, it won't matter much to the males here in about another 5000 generations. Apparently, we guys (or blokes) will have to leave such discussions to the women.
According to a researcher somewhere, the human male Y-chromosome is 'damaged goods' and is becoming more and more decrepit as the generations pass. By about 125,000 years from now, male fertility will be about 1% of present values and the human male will be no more.
Fortunately for the human race, it is possible, even today, to combine the genetic material from two female gametes (or eggs) to create a new individual .. female, of course! So, humanity will go on but in a different form - Homo Shopiens Retailiens!!

There'll be no more war, baseball, football, or toolsheds. Earth will be terraformed to make the sky pink and O'Neill colonies will consist almost entirely of shopping malls, some over twenty kilometres long!
There'll be no more fathers, grandfathers, brothers, uncles or sons and the meaning of the term 'female' will be academic. There'll just be people.
So much for "It's a man's world". Make the most of it while the going's good, fellas!!
:laugh:

*Geez, Shaun, what are women in Australia like? Not that I'm much of a collectivist, or go for collectivist assessments. Anyhow, here in the good old U.S. of A. there are plenty of women who seem quite masculine. For instance, the female boxing champ I saw a photo of on Sunday, in a restaurant; and lo and behold, yesterday morning she walked into said restaurant with an older man. Her name's Kathleen, she might be 18 or thereabouts...but she looks like a 15-year-old boy with short-cropped hair and the works (her prerogative of course; to each their own). She could beat the living daylights out of me if she liked. Quite a few American women are into martial arts, body building, etc. I'm rather feminine for my society and the times, but I'm not at all like the female stereotype you depict.

Byron: "It's widely known the the male chromosome is "damaged goods"...but women concieve more male embryos than female to make up the difference..."

*Are you sure? I read, around 1993, in a medical journal (the AMA, I think; I was taking a break in the doctor's library in a hospital where I worked) that more female embryos are conceived than male...something like 52% to 48%. Also, that nature seeks to create a female; eggs are always XX chromosome (female).

Byron: "and the process of natural selection will always insure that "male viable" children will make it to adulthood to have healthy male offspring."

*This seems reasonable. And I sure hope so! I wouldn't want to live on a planet composed entirely of women. No, I'll go on happily picking up and refolding clothing from the floor, cleaning up all that hair in the bathroom sink (!!!), and helping in trying to figure out "where did I leave my keys/wallet/checkbook?"

--Cindy :laugh:

Shaun Barrett · 2003-10-14 08:02:20

Whoa, Cindy! I was only enjoying a little bit of intersexual 'warfare'.
To really get into that type of recreation, you have to assume males and females are all stereotypical. It was just a joke, that's all.
But the deteriorating Y-chromosome thing is supposed to be for real, though I don't know enough about genetics to express an opinion on it.

dickbill · 2003-10-14 09:56:16

The human species is still in evolution, the early neanderthals for example, had very strong marked characters, like their famous suborbital bumps, compared to most recent neanderthals, it could be because of a cross with modern sapiens sapiens, local geographical differences or a real trend in the neanderthal specie, but still, they were neanderthals.

For Homo sapiens sapiens, a recent skeletton has been found in europe recently, it would be the oldest european specimen and it displayed marked anatomical features, like gigantic molars. Again some suggested a cross (with neanderthals this time), or normal archaic characteristics. In any case they were Homo sapiens sapiens, not a different specie.

This represent cases of speciations, not really "macroevolution" cases, and it is conceivable that our specie is still under speciation. But as I said earlyer, I think that we evolute now under Lamarckian mode rather than darwinian mode because we transmit acquired characters (in the form of information, not genes) to our offspring. I just have extended the Lmarckian concept as I have described previously. So I don't think that under lamarckian mode, we are slave of contigency and randomness like under darwin.
We could as well decide to clone the degenerating Y chromsome and make a patch with it, you know, like when we update constantly windows with patch to fight virus etc

dickbill · 2003-10-14 10:14:42

I am sure that the concept of evolution under different mode (pure darwinian for lower organisms such as bacteria, pure lamarckian for higher organism able to asquire and transmit information such as human, intermediate for other organisms) doesn't hurt the chemists.
Chemist are used to describe the chemical bond either as a pure ionic bond like in a salt NaCl, a pure covalent bond like H2, or a mixed ionic/covalent like HF. Most chemical have mixed chemical bonds, that doesn't hurt the chemists that the world is not pure.
But I am sure that many evolutionists would discard the idea to integrate a lamarckian mode of evolution just because it put into question their quasi religious beliefs in an immacculate darwinian model of evolution, which would then become a 50% Darwinian, 50% Lamarckian model of evolution.

I just watched a documentary about tigers in africa recently. Tigers learn to hunt, improved their skills and transmit these improved skills to their offsprings. Replace skills with organs and you say what said Lamarck in a slightly different way.

clark · 2003-10-14 10:23:54

Perhaps it works via activied genes from specific environmental input. These activated genes then have the opportunity to be transmitted into offspring, or, the offspring are more likely to exhibit these enviornmentaly-specific genes becuase they live in the same type of environment as their parents...

How much do we know about the formation of new gene squences due to environmental changes within a species? Very little I would guess. Yet I am willing to bet there is a mechanism that allows the environment to 'encode' our gene squences to be transmittable to offspring.

So, as the environment changes, it would slightly alter the genes of species, letting some genes express themselves, and some not (a function of proteins, right?), and thus the new squences are more likely to be transmitted.
???

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Re: Biological evolution - prebiotic chemistry, biogenesis, evoluti

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