What do Martians Look Like?

GuanYin

To be fair we have a very limited and biased view of biology.

Its highly probable that life elsewhere, were it similar to us, would build on different amino sequences and thus have DNA-life substances based on different base pairs, maybe with more or less than four.

The thing is we don't know. We don't even know what we are looking for and our limit of biology is, as I said, so limited, that we may not even recognise it if we find it.

On earth itself, life is extremely adaptable and can survive in nearly any condition. "Life finds a way" as the saying goes. I find it hard to believe it didn't find a way somewhere else and you never know, while we are all looking at "Earth-like" planets, there could be a small ecosystem on some cold lump of rock out there.

williamgrogan

I don’t believe that, generally speaking, live elsewhere will be that different. A basic concept in Science is that the laws of nature work the same everywhere.

I wouldn’t even be surprised if at the DNA level it’s the same. Life that is sophisticated, large, complex, long living like Earth life may be very similar. I don’t expect to find complex life in Stars or in the atmosphere of gas giants (satellites of gas giants maybe) or on asteroids.

Any other planet that is as full of life as Earth’s will have it’s equivalent of bacteria, grass, flowers, trees, insects, birds, fish, tigers, deer, etc.. They may even look similar. If the star is different maybe the grass will be red, but it will still behave as grass. Out of all the millions of species that ever existed on Earth we are the only intelligent one. I think that for every million planets with bountiful life, intelligent life may only exist on one and that’s why the radio telescopes are hearing nothing.

GuanYin

Originally posted by williamgrogan
I don’t believe that, generally speaking, live elsewhere will be that different.

Good for you, it does't mean that its the case.

Originally posted by williamgrogan
A basic concept in Science is that the laws of nature work the same everywhere.

In this case what laws of nature are you applying?
Also, can you tell me where this concept occurs with reference to Biology.
We have already seen a demonstration of a 6 base DNA structure. Why couldn't a life form evolve with this? The rules would chance for a number of technical reasons I won't go into here.

Originally posted by williamgrogan
I wouldn’t even be surprised if at the DNA level it’s the same. Life that is sophisticated, large, complex, long living like Earth life may be very similar. I don’t expect to find complex life in Stars or in the atmosphere of gas giants (satellites of gas giants maybe) or on asteroids.

I wouldn't be surprised either way, because I don't know. But its extremely unlikely.

Originally posted by williamgrogan
Any other planet that is as full of life as Earth’s will have it’s equivalent of bacteria, grass, flowers, trees, insects, birds, fish, tigers, deer, etc.. They may even look similar..

What are you basing this on? Is there any evidence to support this (there is plenty against it) or is this idle speculation on your part?

Originally posted by williamgrogan
If the star is different maybe the grass will be red, but it will still behave as grass. Out of all the millions of species that ever existed on Earth we are the only intelligent one. I think that for every million planets with bountiful life, intelligent life may only exist on one and that’s why the radio telescopes are hearing nothing.

Again, this is merely speculation. There is a Scifi/fantasy board for this kind of stuff.

williamgrogan

In this case what laws of nature are you applying?

All of them.

What are you basing this on? Is there any evidence to support this (there is plenty against it) or is this idle speculation on your part?

Life fills all the available niches. It will do the same elsewhere. Of course this is idle speculation!

If the star is different maybe the grass will be red, but it will still behave as grass. Out of all the millions of species that ever existed on Earth we are the only intelligent one. I think that for every million planets with bountiful life, intelligent life may only exist on one and that’s why the radio telescopes are hearing nothing.

Again, this is merely speculation.

Which bit is merely speculation?

Are you aware of other intelligent “species” on Earth? I put the species in quotes to indicate that I was being wooly about what I meant by species. I am including Neanderthals in our linage. There were no reptiles with eVoting or Homeopathy!

PS

It's past my bedtime.

GuanYin

Originally posted by williamgrogan
All of them.

I'm not aware of any law of nature that specifies how many base pairs or what type of base pairs occur in a life form. Nor are life forms limited to DNA useage. In fact the "laws of nature" don't apply to the points you were making. Perhaps you would expand on what you meant.

This is your friendly warning, I've seen you posting in other forums where you ignore the debate and continue responding affirming your point of view. I consider this trolling or at the very best spamming.

It won't be tolerated here. Either back up your view point with an arguement or don't post.

Originally posted by williamgrogan
Life fills all the available niches. It will do the same elsewhere. Of course this is idle speculation!.

Of course, all available niches includes the possability of niches that don't exist on this planet, or which we can't concieve.

Originally posted by williamgrogan
Again, this is merely speculation.

Which bit is merely speculation?!.

Are you aware of other intelligent “species” on Earth? I put the species in quotes to indicate that I was being wooly about what I meant by species. I am including Neanderthals in our linage. There were no reptiles with eVoting or Homeopathy!

We don't know there was no intelligentlife before us. We have no evidence for it, but then we have no evidence against it. The actual fossil record we have on all previous life is pretty scant. What we have on our own ancestors is incredibly scant. We have a firm idea of what came before us, time can wipe away alot of evidence.

Its improbable, but you can't make any conclusive arguement. Noone can. Oh and as for your red grass ..... huh?

williamgrogan

This is your friendly warning, I've seen you posting in other forums where you ignore the debate and continue responding affirming your point of view. I consider this trolling or at the very best spamming.

It won't be tolerated here. Either back up your view point with an arguement or don't post.

In two weeks there has been only one comment on this thread. It’s not exactly looking lively, but then with the supercilious attitude you exhibit in the quoted comment it’s hardly surprising people are slow to post. Needless to say I totally reject your accusation. I think it’s based on the fact that I deeply challenge people’s opinions and why they subscribe to them.

All of them.

Are you suggesting that some or all of “the laws of nature” will be different elsewhere?

I'm not aware of any law of nature that specifies how many base pairs or what type of base pairs occur in a life form. Nor are life forms limited to DNA useage. In fact the "laws of nature" don't apply to the points you were making

In the primordial Earth’s oceans over a period of millennia there was undoubtedly a very large number of chemical reactions. The DNA mechanism we now have came about after the evolution of those reactions into complex chemicals that are the pre-cursors of life. Either you believe that our DNA is a fluke or that it evolved out of many alternatives and is the “best”. Water for example has the same small freezing to boiling temperature range throughout the universe. (I am aware air pressure affects the absolute numbers.) Note that I am not saying that I think that DNA has to be exactly the same as here but I am saying that I think it is likely that it is and that if its different it’s likely not to be too different.

We are speculating. Neither I nor you know the answers and have very little to go on.

Of course, all available niches includes the possability of niches that don't exist on this planet, or which we can't concieve

Now who’s getting into SF?

We have a broad and probably typical spread of niches here. I think oceans under the crust of Europa will not be much different vis a vis evolution than say a surface ocean. We may soon know.

Conceive one then that will produce life but totally different.

I accept that intelligent life may have existed in some other species on Earth but as you say yourself, “Its improbable”. I am well aware of the fact that I cannot prove it. We can only speculate here, we cannot prove anything.

The Drake Equation that I referred to is only about probabilities.

Red grass

The predominant colour of plants that use photosynthesis may be related to the type of star. I gather that green chlorophyll is the optimum for our star.

Please note that I am not claiming to be an exobiologist.

GuanYin

Originally posted by williamgrogan
In two weeks there has been only one comment on this thread. It’s not exactly looking lively, but then with the supercilious attitude you exhibit in the quoted comment it’s hardly surprising people are slow to post. Needless to say I totally reject your accusation. I think it’s based on the fact that I deeply challenge people’s opinions and why they subscribe to them.

This part of my post is not open for discussion. It still stands. If you have anything else to say on the matter PM me.

Originally posted by williamgrogan
Are you suggesting that some or all of “the laws of nature” will be different elsewhere?.

Which laws of nature state that DNA can only occur in the way we have observed it here? I've already pointed out the evidence that any extraterrestial DNA may be very different to ours and that as a result we can't predict the evolution or effect on any life it generates. All you have said is "laws of nature". Its not an arguments. Please explain what you mean.

Originally posted by williamgrogan
In the primordial Earth’s oceans over a period of millennia there was undoubtedly a very large number of chemical reactions. The DNA mechanism we now have came about after the evolution of those reactions into complex chemicals that are the pre-cursors of life. Either you believe that our DNA is a fluke or that it evolved out of many alternatives and is the “best”. Water for example has the same small freezing to boiling temperature range throughout the universe. (I am aware air pressure affects the absolute numbers.) Note that I am not saying that I think that DNA has to be exactly the same as here but I am saying that I think it is likely that it is and that if its different it’s likely not to be too different.

On this plant there are at least a hundred different tactics employed by DNA in replication, reproduction and the formation of a creature. Each of them occurs because it suits the environment and condition best suited to the creature in question. Frogs for instance have a range of complex enzymes which are synthesized to account for the temperature changes that may occur in the formation of the frog. Mammals bypass this system by maintaining a constant temperature throughout.

Life finds a way. The real answer is we don't know. But unless you believe in devine intervention (which you don't seem to) then the initial formation of a 4 base pair DNA structure (actually, its most probable that RNA formed first and that DNA came much later, which would matchup nicely with the way DNA replication works) was a fluke. The initial chemicals came together by chance, it worked and they went from there.

There is no scientific evidence to show that this is the only way DNA can come about and a hell of a lot of evidence to suggest that it can form in a totally different way. At this point the rules change totally. We don't know what the environment is like, we don't know what effect a different "DNA" structure will have on the way the creature functions and evolves. It may be that extra base pairs make a creature less or more likely to mutate, we just don't know. However, all of these factors taken into account. It is very unlikely that the conditions of evolution in another place, with different gravity, planetary cycle and chemical environment would give rise to a creature that would be anything like us or life here.

Originally posted by williamgrogan
We are speculating. Neither I nor you know the answers and have very little to go on.

Yes, but I'm giving a scientific explanation to my speculation (which is the best we can do). You're just stating your personal opinion.

Originally posted by williamgrogan
We have a broad and probably typical spread of niches here. I think oceans under the crust of Europa will not be much different vis a vis evolution than say a surface ocean. We may soon know..

Why are you focusing so close, the probability is that any comlex life is far far beyond our reach.

Originally posted by williamgrogan
Conceive one then that will produce life but totally different...

A creature evolving on a high gravity plant, from a 6 or 8 base paired DNA-like structure with a non 02 atmosphere and different class of sun would be very unlikely to be humanoid, or even a biped. It would have a different rate of evolution and the need for "intelligence" to arise would be due to factors unrelated to our own.

Originally posted by williamgrogan
I accept that intelligent life may have existed in some other species on Earth but as you say yourself, “Its improbable”. I am well aware of the fact that I cannot prove it. We can only speculate here, we cannot prove anything. ...

Exactly, but if you wish to view these matters of a scientist, instead of asking "is there any evidence for that" and then discounting it, you also must ask "is there any evidence against it". This is a common failing among even trained scientific minds and especially among media science. The answer here is, there is no good evidence for or against. The only thing we can say for sure is that, given our fossil recovery record, its very likely that we could miss a civilisation that existed over 1 million years ago.

Originally posted by williamgrogan
The predominant colour of plants that use photosynthesis may be related to the type of star. I gather that green chlorophyll is the optimum for our star.

Please note that I am not claiming to be an exobiologist.

Its actually related to the type of energy emitted which isn't always dependant on the type of star. Can you give any factual data as to why you believe this to be the case?

Tazzle

Jesus, with this point, counter-point whine I prefered this board when it was dead.

williamgrogan

I think Tazzle is an Alien and wants to quash any discussion on them.

Am I correct in saying that ALL life examined so far has the same DNA? Including extremophiles.

GuanYin

It depends entirely what you define as life.

williamgrogan

I'm sure you agree that there is no 100% agreed definition of "Life".

But will the following do to answer my question? My question is specific to life on Earth (unless you think we have been examining the bodies of dead Aliens).

To be living they must replicate, minimum size 1 cell (therefore a virus or a prion is not life), take in energy and grow. (I could add evolve and react but I don’t think that’s necessary.)

GuanYin

Hrmmm weird I thought I replied to this.

Well I wouldn't discount viruses as life just yet. There are many people who think that virus-like particles were one of the stop gap stages between the formation of RNA (or DNA if you want to make a huge leap of faith) in the "primordial ooze" and the evolution of the first cellular organisms. (others think viruses *are* extraterrestial life, but I would imagine we agree in our opinion of that idea).

If you want to ask, if all life on earth has the same DNA structure. Then yes, its common on this planet. However I think that a reductionist model that simplifies the situation to suit a certain point of view (and I believe an incorrect one).

While we all have the same DNA stucture, it has been clearly shown in work spanning from 1988-2004 that a working and replicating "DNA" helix can occur with different types, pairings and numbers of nucleotides (Benner at al, Nucleic Acids Research, 2004). While this was an in vitro study, it highlighted a few important points. Firstly the conditions for the formation of a helix is specific enough. That is, you need things to be just right for the formation ofany given helix. Secondly, not only are you not limited to 4 nucleotides in Helix formation (Benner managed up to 12) but they can also be replicated by enzymatic processes just as Watson-Crick DNA is.

Now, it all probability, the formation of the first RNA/DNA molecule was a chance interaction between chemicals under just the right conditions. The amino acids involved are not uncommon, but the conditions are specific enough to deem the liklihood of it happening in exactly the same way again unlikely (or at least unlikely to be the general rule). However, it is possible that molecules such as those formed in vitro could be formed.

In this case, we cannot predict what any organism would be liked. Not only do we have to take into account the changes to replication, proofreading and mutational potentials but also the phenotypic constraints of the planet in question. We already know that evolutionary mechanisms are diverse and its quite possible that there are more ways to form things such as immune systems and neurological pathways than the ways we observed. Of course its not provable just now, but based on the diversity of evolution in our own tiny habitat and gene-pool (metaphorically speaking) its likely. The laws of nature (at least the ones applying to DNA formation) do favour "DNA" types different to our own.

Often you will see popular science books on this subject marvel that The Earth had just the right conditions for the formation and evolution of life. This is a very introspective comment and in all probability wrong in one major regard. The Earth had just the right conditions for the formation and evolution of the type of life we know. And thats just it, we are confined to a small habitat. If you were only ever to have experienced the habitat of the jungle, you might expect creatures living under the sea to be physiologically the same as you. This analogy works with the Earth on a molecular level, all we know if life on earth and the conditions on earth, we would be very closed minded and quite unscientific to expect everything in theuniverse to mirror our own molecular ecology, it is almost Luddism.

Incidently, Brenner is a NASA consultant and has briefed them on traits of non-terran DNA in the search for extra-terrestial life.

Scruff

of course there is!

Look at all those fricking u.f.o.'s flying around the place. proof enough! sheesh...

Stark

While we all have the same DNA stucture, it has been clearly shown in work spanning from 1988-2004 that a working and replicating "DNA" helix can occur with different types, pairings and numbers of nucleotides (Benner at al, Nucleic Acids Research, 2004). While this was an in vitro study, it highlighted a few important points. Firstly the conditions for the formation of a helix is specific enough. That is, you need things to be just right for the formation ofany given helix. Secondly, not only are you not limited to 4 nucleotides in Helix formation (Benner managed up to 12) but they can also be replicated by enzymatic processes just as Watson-Crick DNA is.

The 4 base-pairs used by our DNA are the 4 that offer the most reliable form of DNA. It's likely that on another planet natural selection would eventually reduce the number of base pairings to the same 4 we use.

Then again, a different arrangement of pairings might allow more mutations leading to greater diversity and more rapid evolution.

GuanYin

Originally posted by k.oriordan
The 4 base-pairs used by our DNA are the 4 that offer the most reliable form of DNA.

True, but only using the DNA replication enzymes we know. Modified enzymes could offer the same replication stability. I think the base pairing was slightly different in the modified DNA and the enzymes had to be modified too.

Thereis also the chance that more base pairs would offer a more conserved organism and mutations would be less pronounced but I'm not sure that evolution actually works at a base pair level so I dunno if we could lose them during evolution. Actually I don't think its the case but I'll ask someone i n the know tomorrow.

Capt'n Midnight

4 base pairs in groups of three give you 64 words - but these only translate into ~20 amino acids - so there is a bit of redundancy.
one interesting side effect of this is that some DNA changes do not affect the protein sequence decoded, it also allows organisms that live at high temperatures to evolve a DNA sequence richer in CG bases which is more stable at higher temperatures.

To be pedantic you could say that uracil is actually a fifth base - but is used in RNA rather than DNA. Also some bacteria methylate some of their bases to distinguish their DNA from that of parasites..

The DNS --> amino acid mapping is resonably conservative - but not all organisms use the same codes for the same bases.

On this planet - most life has to compete with the products of a four billion year arms race - with lots of disasters to upset any stable equilibrium - some say that a planet without a moon (less tides, less weather) and a more circular orbit (venus) (less seasons) would be less likely to develop more advanced life.

RNA can be used to transfer genetic info and some configurations have enzymatic properties. - The main advantage of DNA is that the opposite strand gives an error correction mechanism. - in an more benign environment - no oxygen - less UV - less mechanical movement - less temperature changes and less competition - it could survive longer.

Some reckon there are two phases of life - first you get self replicating molecules in the organic soup and eventually it's all used up. at this stage "life" could stop unless a more advanced version comes along eg: something with a cell wall - even something as simple as a liposome which can keep it's molecules away from the neighbours and replicate at their expense - uptill this stage no energy source is needed - all the chemical energy in the organic soup has been used. - now the challange for proto-life is to develop a mechanism to extract energy from some chemical breakdowns to power some macro molecule building.

Much Much later on the challange will be to extract energy from sunshine - once this in achieved then life can continue indefinitley.

But none of the above would even reach the stage of slime (production of exces complex carbohydrates / proteins and excretion of them) - that would be far in the future.

Chances of self replicating molecules in the organic soup - very high.
Chances of them surviving beyond this stage - much lower.
Chances of them getting to photosynthesis much much lower..

williamgrogan

I accept what you say and I am not saying that I believe that life elsewhere will definitely be the same as here. I am saying that it wouldn’t surprise me if it was. I do not believe that one freak chemical event led to the current DNA structure. I think many different types may have arisen and maybe even still do but if ALL DNA now on Earth is exactly the same does that not indicate that it is either the only one possible (or practical) or the best? Why would it be the only one otherwise?

To put it another way, if you are correct then I would expect that many slightly different DNA structures evolved but then there should still be many different types if we expect that other planets will have different types too.

Gravity or air pressure or the distance from the parent sun is unlikely to change the number of base pairs. I do think we will find really strange life in really strange places but I think that will be the exception and I expect no sophisticated life or intelligence.

There is an opinion (the prevailing one?) that if you re-ran evolution you would end up with totally different life forms, I don’t actually believe that. At any given time it would be different but I still think hundreds of millions of years after life became multi-cellular that you would have things that looked like birds, animals, grass, flowers, etc.. I don’t think too many animals would evolve wheels. The only thing that would in all probability be missing would be an intelligent animal.

I think that if and when we land on another world that is similar to Earth (size, distance from Sun/Size of Sun, age, Moon) that it would perhaps to the surprise of the crew look just like another continent on Earth.

Even the data that was reported yesterday from Opportunity shows many surprising Earth like geological formations. One of the most common sentences is, “we often see that on Earth, or we can tell because it’s like that on Earth.” If that Mars meteorite AH… actually has evidence of life, it does look like bacteria.

Roll on JIMO and a decent Titan lander.

For years I have supported human exploration but the success of Galileo, the Mars Rovers and hopefully Cassini is beginning to change my mind. For 50 billion dollars we could build a lot of very sophisticated rover type explorers.

Capt'n Midnight

Originally posted by williamgrogan
Gravity or air pressure or the distance from the parent sun is unlikely to change the number of base pairs.

As I posted here in earth CG base pairs are favoured by high temperatures - less stable combinations would not be disadvantaged in other environments.

There is an opinion (the prevailing one?) that if you re-ran evolution you would end up with totally different life forms, I don’t actually believe that. At any given time it would be different but I still think hundreds of millions of years after life became multi-cellular that you would have things that looked like birds, animals, grass, flowers, etc.. I don’t think too many animals would evolve wheels. The only thing that would in all probability be missing would be an intelligent animal.

Have a look at the cambrian explosion and the phyla that were around then - most of the animals were very weird and some were unrecognisable for a long time - Burgess shale and all that..

GuanYin

Originally posted by williamgrogan
if ALL DNA now on Earth is exactly the same does that not indicate that it is either the only one possible (or practical) or the best? Why would it be the only one otherwise?

To put it another way, if you are correct then I would expect that many slightly different DNA structures evolved but then there should still be many different types if we expect that other planets will have different types too.

Well first off, we don't know how long the naturally occuring DNA took to get off the ground. It may have taken along time. Perhaps other DNA forms occured before hand and didn't cut it here. Perhaps by the time conditions favoured another form of DNA, DNA as we know it had leeched the resources required for other types to form. Or even yet, perhaps it *did* form and even made it to cellular level but was out competed by our cellular ancestors. Its a mystery, but the lack of evidence proves nothing.

Originally posted by williamgrogan
Gravity or air pressure or the distance from the parent sun is unlikely to change the number of base pairs. I do think we will find really strange life in really strange places but I think that will be the exception and I expect no sophisticated life or intelligence..

No but gravity and air pressure will effect selection during evolution, couple that with a different mutation rate and who knows what you get (Bi-peds would be unlikely to evolve in high gravity, for instance).

Originally posted by williamgrogan
There is an opinion (the prevailing one?) that if you re-ran evolution you would end up with totally different life forms, I don’t actually believe that. At any given time it would be different but I still think hundreds of millions of years after life became multi-cellular that you would have things that looked like birds, animals, grass, flowers, etc.. I don’t think too many animals would evolve wheels. The only thing that would in all probability be missing would be an intelligent animal...

I don't either, I think in all probability we would have no life at all. Or at least, nothing much more complex than hydra.

Originally posted by williamgrogan
I think that if and when we land on another world that is similar to Earth (size, distance from Sun/Size of Sun, age, Moon) that it would perhaps to the surprise of the crew look just like another continent on Earth....

I thik thats your best case/ideal scenario for finding similar lifeforms. However, I would still think it unlikely and I would imagine that over the expanse of the universe, it may even be life in the minority.

Originally posted by williamgrogan
Even the data that was reported yesterday from Opportunity shows many surprising Earth like geological formations. One of the most common sentences is, “we often see that on Earth, or we can tell because it’s like that on Earth.” If that Mars meteorite AH… actually has evidence of life, it does look like bacteria.

While we may have left our ecology in terms of life on Mars, we certinly are playing in the same neighbourhood.

NinjaBart

Originally posted by williamgrogan
I accept what you say and I am not saying that I believe that life elsewhere will definitely be the same as here. I am saying that it wouldn’t surprise me if it was. I do not believe that one freak chemical event led to the current DNA structure. I think many different types may have arisen and maybe even still do but if ALL DNA now on Earth is exactly the same does that not indicate that it is either the only one possible (or practical) or the best? Why would it be the only one otherwise?

Some of that sounds really like creationist arguments I've heard. Are you suggesting that there is rhyme and reason behind it all?

williamgrogan

Some of that sounds really like creationist arguments I've heard. Are you suggesting that there is rhyme and reason behind it all?

To quote myself from another post………

e.g. Creationism is total bullsh1t

I don’t know what you mean by, “rhyme and reason behind it all”. Other than perhaps Quantum events I think there is rhyme and reason behind everything. I don’t think life appeared here by magic. It was inevitable.

I don’t want people to get carried away here, I’m just suggesting that rather than the Universe being full of really weird life, it may be full of really ordinary life.

The temperature & pressure fluctuations that exist on Earth are fairly large and yet we have one type of DNA.

Many of the “weird animals” still looked like say pigs, they had 4 legs, a body and a head. They were made of normal DNA. Some of the “carpet like things” are not all that different from moss & some seaweeds.

didn't cut it here …..

Which is why I’m saying the same can be expected to happen on other planets which will leave them looking like here.

Bi-peds would be unlikely to evolve in high gravity

Eh? There are thousands(?) of objects greater than 500Km in the Solar System and Earth is the solid planet with the highest gravity. If with Earth’s gravity we could have 30m dinos then heavier planets can have bi-peds. Anyway, Earth may be at the upper end of solid planets.

I think in all probability we would have no life at all

Lfe is probably as common as muck. I think (hope? expect? pray? (no cross out pray)) the existence of extra-terrestrial life will be found on Mars (extinct), Europa (simple/new) and maybe Titan (pre-cursors). Life on Earth appeared very early on and was probably inevitable.

we certinly are playing in the same neighbourhood

I disagree with the implication here. I think that most single star systems that have stars that are as old as the Earth will have solid planets similar to here and will have or have had life in most cases.

PS

I remember as a 13 year old typing up sheets of paper containing all we knew about each planet (other than Earth). What we knew fitted on 8 incomplete sheets of paper. I have seen our view of the Solar System go from black and white to full colour.

GuanYin

Originally posted by williamgrogan
Which is why I’m saying the same can be expected to happen on other planets which will leave them looking like here.

I don't get your reasoning behind this. Because something worked here, it can be expected to work everywhere else? Despite the conditions and environment? That is a very unscientific leap.

We don't know that DNA here is even the most effective. We don't know why it specifically evolved. I think for someone who calls himself a skeptic you're being very closed minded. The fact that DNA unlike ours is possible and that conditions in atmosphere, temperature and environment are so diverse across the universe, suggesting that "all life is the same" in the universe is ridiculous.

Capt'n Midnight

The predominant colour of plants that use photosynthesis may be related to the type of star. I gather that green chlorophyll is the optimum for our star.

Red alge - cyanobacteria etc. - many organisms here don't use either of the two common types of chlorophyll. Those that do use Red and Blue light - each of which have photons of differing energy and so are used by the cell to power different reactions - each ratcheting up until there is enough to do something useful.

Light from stars is black body radiation - ie for practical purposes determined soely by termperatures and having the same shape graph. Since plants arent in the vacuum of space the available wavelengths of light is limited by the atmosphere (ozone UV shield) or in the case of some types of seaweed by water.

There is that old chestnut - why is grass green - shouldn't it be black ?

==================================

History is written by the victor - forget the KT extinction, even though it wiped out all the dinosaurs the were about the only terresterial animals bigger than chickens for a very long time - mammals did not compete in most niches, the permian extinction was the big one - most like wiped out - which defined what we look like. Earlier competition in the primordial soup - even a slight reproductive advantage when there were only a few types of organisms would have determined which chemicals would belong to the porbable uniculture.

Most of the history of life on the planet consisted of cyanobacteria in the oceans - multicelluar life only has existed for the last 10% or so - most of the evolution of biochemical pathways was locked in earlier.

BTW: there were of course earlier exinctions than the permian - but no records.

During the early history of the planet there would have been many planertoid / metroide strikes big enough to boil the oceans - life on our planet may have been lucky enough to survive against the odds OR maybe the planet was steralised many times only for "life" to re evolve ...

BTW2: What ever about being bipeds :-
Eyes (organs for detection of light) have been evolved independently up to 20 times depending on how you read the fossil record. some interesting ones - the blue eyes of those very good swimmers , the scallop (AKA shell oil Logo) - those trilobites that had quartz lenses - the octopus that has nerves on the back of the retina unlike us and so has no blind spot - compound eyes - the "third eye" of vertebrates

williamgrogan

There is that old chestnut - why is grass green - shouldn't it be black

I’m out of my dept here, but isn’t it green because that is the optimum colour for absorbing the maximum radiation? It’s green because it reflects green light the most and absorbs the other frequencies. Green was just selected for. BTW GREEN grass IS very successful. I don’t know why it’s not black though? Maybe Chlorophyll cannot be black and Green is the next best vis a vis the output of the Sun and the atmosphere etc..

This discussion is a bit like why are the laws of physics so tuned that stars can form and atoms don’t disintegrate etc… (As a total aside this is the only argument I know that supports the possibility of a GOD and yet most religious people do not even know of it.)

We do know that our DNA works very well. We don’t know that any other variation does. You have suggested that other DNA MIGHT have evolved THEN it ALL got wiped out and EVEN if it did, I cannot accept that some fluky event like an asteroid impact swung it towards our DNA on a planet as big as the Earth over billions of years. I think it’s far more likely that our DNA is the best BY FAR and therefore the most likely to appear on other planets. As I said we may soon know.

Is Ockham’s Razor not applicable here? The simple solution is that during zillions of chemical reactions over millions of years in a vast primordial soup that many different molecules evolved and that the best one, our DNA, survived and continue to evolve into more complex “life”, RNA, DNA, Virus type things, Cells etc and therefore this will apply on other planets.

As regards eyes, I bet you that there is a similar spread of eye types on other stable for 4,000,000,000 year planets.

As regards intelligence, I think there will be constraints on what type of creature becomes as intelligent as us. I cannot envisage an intelligent creature with no hands or other appendages for manipulating his world. As a follow on, will they not have to be at least mostly upright because otherwise how do they manipulate their environment? It’s hard to imagine that a ruminant could evolve intelligence (not withstanding the GM cow in the Hitchhikers Guide to the Galaxy.) Scientists debate about why we are intelligent, is it thumbs, uprightness, a chemical fluke but maybe it’s all of them and because it needed all of them it’s rare not to mention that apparently we were down to the last 10,000 proto-humans at one stage.

Incidentally I’m not being close minded. It’s much easier to imagine that life is very diverse. It may be, but I suspect that it will be very similar to us more often than not. Maybe astonishing similar.

GuanYin

Originally posted by williamgrogan
I’m out of my dept here

It hasn't stopped you giving your opinion. However, all you have done is give you opinion. I've yet to see one coherent scientific argument. So long as you are not championing false science and only giving your opinon, I don't mind.

I'm going to ask you to think about some of the statements you've written here. They are questions that might be pointedly asked if ever you were to try and voice these opinions in the scientific community.

Originally posted by williamgrogan
We do know that our DNA works very well.

In comparison to what. You have no frame of reference to make this claim. Its like only ever seeing a Ford Fiesta and claiming that it works so well it must be the best and fastest transport in the universe.

Originally posted by williamgrogan
I cannot accept that some fluky event like an asteroid impact swung it towards our DNA on a planet as big as the Earth over billions of years. I think it’s far more likely that our DNA is the best BY FAR and therefore the most likely to appear on other planets. As I said we may soon know.

Firstly why not? All the evidence of our neighbourhood suggests that impact extinctions were the norm. We also know tha we've been quite lucky in obtaining any fossil record at all, and have most certainly missed more than we can imagine to time. Is this just a personal belief (like religion) or is there some scientific reason you have to argue this?

As for "we may soon know" again, for someone who claims to have a scientific mind, taking DNA samples from two close planets that have shared a common history and claiming they are the norm rather than the exception, is a very biased and weighted arguement for any scientist.

Originally posted by williamgrogan
Is Ockham’s Razor not applicable here? The simple solution is that during zillions of chemical reactions over millions of years in a vast primordial soup that many different molecules evolved and that the best one, our DNA, survived and continue to evolve into more complex “life”, RNA, DNA, Virus type things, Cells etc and therefore this will apply on other planets..

Oh dear or dear, are you using "PHILOSOPHY" to back your arguements? There is evidence to support that there have been many cases throughout the planets history, where "chance" eliminated the "best suited" creature, believe it or not. Natural selection doesn't always readily account for the odd freak act of nature. That said, your whole arguement is based on the fact that DNA here is all that you know. So what you already know must be the best way? Again, thats as close to Luddism as you will get in this arguement.

Originally posted by williamgrogan
As regards intelligence, I think there will be constraints on what type of creature becomes as intelligent as us. I cannot envisage an intelligent creature with no hands or other appendages for manipulating his world.
As a follow on, will they not have to be at least mostly upright because otherwise how do they manipulate their environment? It’s hard to imagine that a ruminant could evolve intelligence (not withstanding the GM cow in the Hitchhikers Guide to the Galaxy.) Scientists debate about why we are intelligent, is it thumbs, uprightness, a chemical fluke but maybe it’s all of them and because it needed all of them it’s rare not to mention that apparently we were down to the last 10,000 proto-humans at one stage.

Well now, since we have mentioned eyes, consider the octopus. Ok, not as intelligent as us, but strongly belieeved to be as intelligent as many canines. Here is a creature with a short life span, no paternal environment, yet a staggering complex neural setup in one of the most unlikely classes of creature to develop intelligence. Its thought that the intelligence evolved for hunting, but even yet, to this level? Now they are not quite human standards and teh community is split over how much awareness they have (although again, the evidence is building up in their favour) but consider how, why and where this intelligence evolved. Yet you seem closed to it all being just like us. A "star trek" universe.......

Originally posted by williamgrogan
Incidentally I’m not being close minded. It’s much easier to imagine that life is very diverse. It may be, but I suspect that it will be very similar to us more often than not. Maybe astonishing similar.

Again, you are taking your arguements in and out of scientific/philosophical context. Earlier you quoted Ockham’s Razor to suppoert yourself, now you denounce it. No consistancy. Surely if the simplest explanation is what you believe you should imagine diverse life. That said, I don't think diverse life is a "simple" explanation, it doesn't quite work like that. It will all depend on the environmment for starters, but the fact is, unless we are wrong about DNA being a chance formation o this planet, and it is in fact some sort of universal biological element, then the likelihood is life will take whatever it can get.

williamgrogan

We do know that our DNA works very well.

In comparison to what. You have no frame of reference to make this claim. Its like only ever seeing a Ford Fiesta and claiming that it works so well it must be the best and fastest transport in the universe

OK then. Our DNA does NOT work very well and there is no intelligent life on this planet.

By ANY frame of reference we are an incredible example of DNA working extremely well. In fact so well that the religious people use this “impossibility” as their central plank in arguing for a God.

impact extinctions

There is no evidence that any impact extinction was complete.

Even if ALL life was extinguished, which I think is unlikely once it got a foothold, then our DNA won the next battle for survival. Again, I do not think an asteroid impact would change the nature of DNA.

As for "we may soon know" again, for someone who claims to have a scientific mind, taking DNA samples from two close planets that have shared a common history and claiming they are the norm rather than the exception, is a very biased and weighted arguement for any scientist.

I do accept that if we find DNA on Mars and that it’s similar to Earth’s that it may be actually related. But there are several other obvious possibilities. Time will tell.

what you already know must be the best way

I obviously meant the best on Earth as it is all there is now. There is no other competing type of life on Earth. If there was, and I don’t say there was you did, then it was beaten and therefore it was not the best.

The Octopus has appendages and is a hunter just like us. Let’s not exaggerate its supposed intelligence just yet. Furthermore when I referred to intelligence I was not talking about dogs or any other animals. I do think there is a fundamental difference between the “intelligence” of any animal and man. That fundamental difference I was arguing needed “hands” and not the level of intelligence of a dog. This is obvious as I know dogs don’t have hands, I have one. A dog that is.

Look – lets get something straight here. I am not saying I do not believe in really weird life forms. They may exist. I however caution against assuming this. Life may on other planets be very similar to us. I suspect that it is.

GuanYin

I just picked up a book today by Ian Stewart and Jack Cohen called What Does a Martian Look Like?. Its about a year or so old so the science in it is recent enough and it very well argued (Wouldn't expect muchless from Stewart).

Anyway, worth a read, very articulate and detailed explanations on exactly WHY life on other planets probably won't have terran DNA or look anything like us.

I am beginning to see a trend in your posts WG, so I think I'll just agree to differ. Its very hard to convince someone who has religious fundementalist-like beliefs of anything no matter how much scientific evidenc eyou show them, once the believe something, their mind is set and closed.

Stark

There's no mention of it in Genesis, God thought we were so brilliant there was no point in trying another project, therefore case closed

albertw

Originally posted by williamgrogan
In fact so well that the religious people use this “impossibility” as their central plank in arguing for a God.

Withought wanting to take this on another tangent...

Central plank? It would be better to start arguing the existance of god from Thomas Aquinuss point of view eg http://www.aquinasonline.com/Topics/5ways.html
If someone felt so inclined to argue of course

Written in the 13th century, so no DNA mentioned.

Cheers,
~Al

williamgrogan

I have argued for 30 years with people as to whether or not there is a god and no one has started off quoting Aquinas.

Creationism has been replaced by Intelligent Design because they believe that Life shows design and could not come about by chance. Dawkins “The Blind Watchmaker” was written as a rebuttal to the notion that if you found a watch you would know it was designed. All religious people I have argued with have said that "it’s impossible that life would have arisen by chance". In the last week a Jehovah’s Witness I was debating with, said, "Life could not have arisen from nothing". The general impression and one apparently held by Syke is that life or at least our version of life was a fluke. I think this is understandable as it is a phrase repeated continuously. I would say that the reason most people believe that god created life on Earth is they literally cannot imagine it starting “by chance”.

I suspect that on any suitable and stable planet that life is inevitable and that the life that will appear most often is the 4 base pair DNA based life that is on Earth.

PS

It’s ironic that even a very remote chance of life appearing holds no water with the man-in-street but many of them will not use MMR because of the extremely slight chance that it may injure their child. They also do the Lotto with it’s 1/1,000,000 odds.

williamgrogan

from

http://www.carm.org/questions/lifeonplanets.htm

Does the Bible tell us if there is life on other planets?

The Bible does not say if there is life on other planets. It simply says that God created the heavens and earth and put man on it. But this silence on the subject does not require that earth is the only place with life on it. But then again, this doesn't mean there is life out there, either.
Let me propose some reasons why I believe there is no life on other planets. Now, I should tell you that these reasons are simply exercises in biblical theology.
The Bible says there is one Trinitarian God. Jesus was God in flesh (John 1:1,14; Col. 2:9; Phil. 2:5-8), second person of the Trinity, and died for our sins (Romans 5; 1 Pet. 2:24). If, there were other beings on other planets that have sinned, then they would need a redeemer. God would have to die for them as well.(1)
Only God can forgive sins. Jesus is God in flesh (John 1:1,14; Col. 2:9), is forever a man (1 Tim. 2:5; Heb. 7:17, 21) and died for the sins of people here on earth (Rom. 5:8). Therefore, I conclude that the only members left in the Trinity to die for the sins of another race would be the Father and the Holy Spirit. But this doesn't seem credible since the focus of the Trinitarian effort in this world has been for the Father to elect a people (Luke 18:7; Rom. 8:33), the Son to redeem them (John 6:39; 17:9,24; Rom. 5:8; 1 Pet. 2:24), and the Holy Spirit to fill, guide, and indwell them (Acts 4:29-31; John 16:13; Rom. 8:9-14). The focus of their effort has been this world and the redemption of mankind, not anywhere else.
Second, if there were life on other planets, would it be possible that they never sinned and don't need a redeemer? I think this question can be answered by the Bible where it says that creation is groaning, waiting for its redemption at the return of Christ (Rom. 8:22). That would mean that all of creation was affected by the fall. When Adam sinned, the ground was cursed and death entered the world. If that is so, then any other beings out there that were made in God's image, would have fallen too since they would be part of creation.(2) I don't see how they could escape the effect of the fall. They would be sinners too and need a redeemer. Then they would fall under the first objection above.
Third, there are only two options available to explain our existence. Creation and evolution. I have studied the theory of evolution and do not believe it is a viable option to explain how we got here. I do not accept evolution for two reasons: The Bible says God created life on earth; that means it did not evolve. Second, the problems of spontaneous life formation are so immense that it is impossible. Also, missing links abound. The fossil record is spotty at best. DNA mutation theory is insufficient to account for life form development. And more.... But this paper is not a refutation of evolution.

WG - I think that solid evidence for life on other planets would cause a major problem for most religions. Would Jusus die millions of times on other planets?

NinjaBart

williagmrogan I'm not a psychologist but did you go to the CBS and have a hard time growing up?

Originally posted by williamgrogan
WG - I think that solid evidence for life on other planets would cause a major problem for most religions. Would Jusus die millions of times on other planets?

what line of reasoning leads you to believe that alien lifeforms are sinners in that sense?

BTW, do you watch a lot of star trek?

GuanYin

Ok, its gone waaaay off topic, split and moved to science where you can debate alien appearance and make up to your hearts content.

Syke

dudara

That was interesting reading.

Well, for my twopence worth, as a physicist and atheist, there is also the theory of panspermia, or the idea that life was "seeded" on different planets at some stage in the past. Thus, life is descended from a common source. Why couldn't an asteroid or meteor have carried the genesis of life to our planet? It's a more credible theory than "God created life", in my eyes anyway.

What I do regret, is that by the time we find intelligent/or otherwise, life anywhere else, I'll probably be long gone. I can't see why life wouldn't exist elsewhere. After all, the whole universe is subject to the laws of physics, from stars to the atoms that compose DNA. It's likely that the same paths will be followed elsewhere in the universe.

williamgrogan

I only posted the bible bit to show how some people think on this matter. It’s also another extremely interesting position vis a vis the potential conflict between religion and science. Life on other planers IS a big problem if God created the universe for man as the bible seems to imply. I suspect that Bush is re-directing NASA away from Science projects for religious reasons. The religious right in America would not be Hubble’s biggest supporters.

The problem with Panspermia is that it fails the Ockham’s Razor test. If life came from elsewhere it still had to originate somewhere. Why not here?

There is now no doubt that life could evolve on Mars and then be carried here on a meteorite after an impact on Mars launched it into space. But then it would still have had to “evolve” on Mars using the same mechanisms that have been proposed for its origin on Earth. While local seeding is possible, across the gaps between the stars? The nearest star to Earth is billions of times further than Mars is. Possible but far less likely.

PS

I don’t answer personal questions from people whose names I do not know. You know my name, I don’t know who NinjaBart is.

BTW do you watch a lot of cartoons?

GuanYin

Originally posted by williamgrogan
I only posted the bible bit to show how some people think on this matter.

If you have any query on your ban. PM me.

Originally posted by williamgrogan
It’s also another extremely interesting position vis a vis the potential conflict between religion and science. Life on other planers IS a big problem if God created the universe for man as the bible seems to imply. I suspect that Bush is re-directing NASA away from Science projects for religious reasons. The religious right in America would not be Hubble’s biggest supporters.

I'm at a loss to figure how religion entered this thread, but I will say that you reasoned out the religious aspect quite well. Perhaps you can take that approach with some of the scientific argument that people have made and you disagree with?

Originally posted by williamgrogan
The problem with Panspermia is that it fails the Ockham’s Razor test. If life came from elsewhere it still had to originate somewhere. Why not here?.

Again, does the use of a philisophical tool of reference not contradict your earlier view points on philosophy?

Originally posted by williamgrogan
There is now no doubt that life could evolve on Mars and then be carried here on a meteorite after an impact on Mars launched it into space. But then it would still have had to “evolve” on Mars using the same mechanisms that have been proposed for its origin on Earth. While local seeding is possible, across the gaps between the stars? The nearest star to Earth is billions of times further than Mars is. Possible but far less likely.

Its quite possible (but unlikely) that earth life originated on Mars or anywhere else . More than anything else the solar rays and space radiation would shread, any organism or DNA that wasn't encases in alot of shielding (admittedly a meteorite would be ideal for this, but there are alot of logistical considerations, it would be as slim a chance as the formation of DNA to begin with).

dudara

The problem with Panspermia is that it fails the Ockham’s Razor test. If life came from elsewhere it still had to originate somewhere.

Obviously. I'm assuming that it didn't originate on earth for the sake of argument. It would be very egotistical to assume that we are the originators of life. But that couls well be the case too, the simple point is we don't know.

simu

Hmm, given how strange some earth life forms that are (e.g. deep sea organisms) and that these are still related to us, I think that alien life would be very different indeed. In terms of communicating with intelligent alien life as well, I don't think we'd find it easy to relate to such life forms beyond maybe some shared scientific ideas. We're very much locked into a certain human way of reasoning and it's likely the reasoning ability of alien intelligence would again be vastly different to ours.

For example, would a human have the proper physical apparati to produce the vibrations (or whatever would be required) for an alien language and even if we did, it's extremely unlikely the alien language would fit into the same pattern of "universal grammar" common to all human languages.

GuanYin

Originally posted by simu
Hmm, given how strange some earth life forms that are (e.g. deep sea organisms) and that these are still related to us, I think that alien life would be very different indeed.

Seeing as you're into SF simu, you reminded me of a short SF story published in Nature - Monolith, Vol. 408, #6815, December 21, 2000 (p. 913).

The story is subscription, otherwise I'd paste it here (copyright etc ) but I'll give you a short synopsis.

The story revolves around a creature from an alien world. We learn that there is a choice of sex in this planet, they can be male, females or caretakers.

Before the decision, the creatures live in a bed of "oxyhydride slush" and then can choose to fly up to the sky where they will either find a large fat female and bind with her to mate, become female themselves and become fat and large or find a nest of eggs on the ground and care and nurture them as an asexual caretaker.

We learn that the sky of this world has a hot ceiling of volcanic rock above them and and cold slush marshes overlying icefields below. The narrator eventual becomes a caretaker and stives long and hard to become "the best caretaker in the universe", until one day it returns to find its nest destroyed by a monolith that has come poking up through the marsh where the nest had been. Other of its kind illuminate and examine and study the monolith but cannot make out what it is, or the nature of the markings that adorn it.

it looks like this

==============================================

Its a cool story looking at something we know a bit about from anothe rperspective and the creature itself mimics that of a creature we all know oursleves.

dudara

Simu, that's an extremely valid point. Biologically, other life might be similar, but we are human, and are very unique in that sense (Especially if you watch Star Trek where humans are always considered determined, brave and resourceful!!)

It's the mindset of alien cultures that will be the most different.

Syth

It's the mindset of alien cultures that will be the most different.

True. If there was an alien civilisation it probably wouldn't resemble our civilisation a lot. Human nature is increadably determined by how our species evolved, from our group size to marital monagomy. But if say, ants had evolved intellegence, the the ants civilsation would be very strange.

Orson Scott Card wrote 'Ender's Game' that involved a war between humans and 'buggers', a insect-like race. They have a hive mind, so if there are a flock of 100 buggers, only the queen is intellegent. This is the basis of the human-bugger war. The buggers don't know that all humans are sentient, so they kill any humans they find, becasue to them, they aren't killing sentient beings, they are doing nothing more than trimming toenails.

The (not as good) sequal to that book was 'Speaker for the Dead'. Again intellegent aliens are involved, this time called piggies. The piggies are infected with with a virus that recombines thier DNA with that of plants, so when they die, they spend the rest of their life living as sentient trees. The piggies don't know that humans don't have a 'third life' (as they call it), so they see no problem with killing people.

Both these books show that how a species evolved is very important to how the species acts. Makes you think...

mr_angry

The sooner we meet an alien civilisation though, the more likely they are to be vastly more advanced. Given that we have no means of space travel, it pretty much leaves it up to them to come and find us. If they are capable of that, then they will obviously be far superior. Lets just hope they treat other life forms with more respect than we seem to treat animals / other races.

As for the martians themselves - most likely microscopic, and fossilised beneath about 8 feet of sedimentary rock. The one thing they go to prove is that life is capable of evolving on other planets, and thus we may not be so special after all...

Capt'n Midnight

Originally posted by mr_angry
The sooner we meet an alien civilisation though, the more likely they are to be vastly more advanced.

Reminds me of an Asimov? story Nothing for Nothing? where a spacefaring race comes across a primitive race who are living on the threshold of extinction. So he trades them the knowledge of basic weapons - spear in excahange for a new way of viewing the universe - representational art.