Extraplanetary Dimorphism?

[Starwhip]

On another planet in another solar system, could life have evolved into male and female representatives of a species like it has on Earth? Or is it more likely that organisms there reproduce asexually, or don't reproduce at all?

If anyone finds/has found a scientific source proving any of the above, I'd like to know. It's for a little something that I'm writing. Even if you don't know for sure, an honest opinion would also be appreciated.

[Skyler4856]

... is incredibly useful. The first and foremost reason may be found in the uncertainty given when two organism contribute DNA. This uncertainty allow the species at large to prosper.

[rodion]

evolving some kind of sexual reproduction is highly beneficial to any species of organism wherever it is because it greatly increases the amount of diversity in the gene pool (from semi-random mixing of the parent DNA, increasing the rate at which natural selection can hit on something beneficial) and because it helps get clean up flaws at a much higher efficiency (if a self-cloning organism has a detrimental mutation, it can replicate and its descendants will preserve it, whereas in an obligately sexual organism, if the flaw reduces sexual fitness it will quickly die out of the gene pool). on that basis it's likely that any alien life of greater than primitive unicellular complexity will probably develop some sort of sexual biology, on the basis of convergent evolution.

[Aethon]

"This is indelicate of you, Louis. One does not discuss ... with an alien race." A head emerged from between Nessus’s legs and focused, disapproving. "You and Teela would not mate in my sight, would you?"

"Oddly enough, the subject did come up once, and Teela said -- "

"I am offended," the puppeteer stated.

-- from Larry Niven, in Ringworld (1970)

Follow the arrows at the bottom of each page. Plenty of stuff in here to help a writer.

Alien ....

http://www.xenology.info/Xeno/12.0.htm

Edit- Wow autobot edits out a word very similar to six.

[LordFerret]

On another planet in another solar system, could life have evolved into male and female representatives of a species like it has on Earth? Or is it more likely that organisms there reproduce asexually, or don't reproduce at all?

If anyone finds/has found a scientific source proving any of the above, I'd like to know. It's for a little something that I'm writing. Even if you don't know for sure, an honest opinion would also be appreciated.

Considering we've not yet encountered any lifeforms other than those our own world presents us, I'd think you'd have a hard time finding any such 'proof' for either argument. As far as personal opinion, I can't help but see and acknowledge that much of everything we know of the universe seems to lean towards things (shall I say) 'bipartite' in nearly all matters.

[kerbiloid]

Your question would be splitted.

1. Whether those individuals exchange their genes? - Even bacteria do this, this is a simple and effective way to exclude ill genes from a population and to spread around the healthy ones.

2. Whether their genders are determined genetically? - Not necessary: crocodiles and some fishes anatomic gender is defined without any XY's, and they are enough high-level life forms.

3. Whether their genders look different anatomically? - Not necessary: cats, dogs and horses males and females look similar (except of their clamp-o-trons).

4. Whether their genders have different modes of life, customs, etc.? - Not necessary, but almost certainly, as almost all Earthlings do.

According to Prof. Geodakian theory, the main purpose of gender dimorphism is to split a population to two subsystems.

A conservative subsystem (most often  "females") is more cautious, conservative and is used as a genetic treasury: "keep these pieces as viable".

An operative subsystem (most often  "males") is more adventurers and prospectors, they are used as test pieces: "will this genes combination die or somehow not".

So, some gender dimorphism would be anyway, but an advanced civilization may eliminate this at their will as useless. But may let this stay  until they become some inorganic form (robots, eletric impluses, etc).

[RainDreamer]

Whether their genders look different anatomically? - Not necessary: cats, dogs and horses males and females look similar (except of their clamp-o-trons).

Not to prove/disprove this point, but I would like to point out an interesting species on earth: https://curiouscox.wordpress.com/2012/01/11/the-spotted-hyenas-she-...../

The from the outside, a female spotted hyena looks almost exactly the same as a male, even down to their genital. They just work differently mechanically inside. Interesting to think about.

About the main topic, I wonder... why does it have to be dimorphism or none at all? Why can't there be more combination? Like 3 sexes, A/B/C that can work in much more combination and variations? Does most of the dimorphism on earth is due to the evolution path that the species on earth taken? What would happen if they are put in a different environment than earth? Likely they would evolve differently, right?

Edited December 10, 2014 by RainDreamer

[kerbiloid]

As I have read, some mushrooms have 23 gender types, so 2 is an option.

I'm not a biology specialist at all, but looks that 2-gender model is a pure probability compromise between diversity and simplicity.

Also if I may recommend, this book was amusing for me: http://en.wikipedia.org/wiki/The_Selfish_Gene

[helaeon]

One thing I always try to remember in a xenobiology context is: it's probably weirder and involving chemistries, physiologies, metabolisms, and mechanisms we will never think of on our own. We've yet to exhaust even what is possible using our biochemical and cellular setup. I love when we find things like the black smokers because a lot of people who thought they had the limits figured out and claim things impossible have to eat their hats. (In that case biochemistry working well in excess of boiling temperature, multicellular, and thriving!)

Yes, the way we do things on Earth could be incredibly efficient and really the "best" way so you'll see life everywhere trend in that direction regardless of their chemistries.

What if that life is using a genetic molecule different than ours? What if this molecule self replicates differently? What if it's manner of randomness is different (rather than the process of meiosis it does something different)? What kind of reproductive necessities would come about in the creature's behavior because of those differences?

An example would be that in plants an individual possessing multiple genomes can be hugely beneficial where as in animals that is absolutely deadly. Just because multiple genomes present in an animal will kill them well before birth, doesn't mean in every organism that must be true.

As long as physics allows it and the chemistry is reasonably efficient. Life could try it somewhere that something else that is efficient, like what we do, hasn't already taken hold.

It must also be remembered that you see highly conserved features among large swaths of the tree of life because there was one organism that started going down that path, and all the life after it shares traits with that one organism. That doesn't mean all those traits are required, some were, but not all. Example is bony fish and sharks. There's no reason that sharks couldn't have went the direction the bony fish did and ended up evolving traits needed to live on land and we'd all have properties derived from shark bodies rather than bony fish. (Neil Shubin's Inner Fish explains this idea really well)

Again though the plausibility comes back to the demands of the biochemistry. Like a genetic molecule with more than 2 strands. There would be no point in 3 or 4 and would needlessly complicate the organism's metabolism and reproduction. Error correction could occur via some sort of parity rather than proof reading proteins, but how would that work chemically using very weak bonds and how would that correction occur spontaneously? In a low population situation you don't want to require more than 2 individuals needed to make offspring, preferably as many as possible to replicate those genes as much as possible. Kerbiloid posted about the Selfish Gene, that's the idea here. Each gene, each idea, wants to replicate as much as possible. Successful ones do and become nearly ubiquitous in the population and deleterious ones exist in low concentration. Neutral ones are often common but as they don't hurt or hinder can flux in concentration in the population. Anything that defeats this dynamic in the function of reproduction will itself be out-competed by a method of reproduction that obeys this idea.

[magnemoe]

Not to prove/disprove this point, but I would like to point out an interesting species on earth: https://curiouscox.wordpress.com/2012/01/11/the-spotted-hyenas-she-...../

The from the outside, a female spotted hyena looks almost exactly the same as a male, even down to their genital. They just work differently mechanically inside. Interesting to think about.

About the main topic, I wonder... why does it have to be dimorphism or none at all? Why can't there be more combination? Like 3 sexes, A/B/C that can work in much more combination and variations? Does most of the dimorphism on earth is due to the evolution path that the species on earth taken? What would happen if they are put in a different environment than earth? Likely they would evolve differently, right?

Problems with more than two sexes is that you complicate stuff with little return. In short an mutation who let you manage without one of the three sexes would have an benefit.

About dimorphism we have all sort of variations on earth however not so much among higher animals, not sure if this is random or that pretty similar sexes works better.

Hermaphrodites or ... change at age should work well to but is rare.

[crubs]

Theoretically this is entirely possible.

The key differences between male and female ultimately comes down to parental investment, and this begins at the gametic level. Males give sperm cells with small mass and make practically no contribution to the developing organism other than DNA. Females on the other hand have massive gametes that are energetically expensive to make, which limits her ability to make them. Furthermore, females in our species have to carry that egg around for nine months as it drains her nutrients, while the father gets to sit around, eat, and watch TV. Even after pregnancy, they still drain mom's nutrients in the form of breast milk.

In other species, females have to sit on their eggs for a long period of time before they hatch. Furthermore, females tend to be primary caretakers until the children are on their own. With all the investment and work females have to put up with, they tend to be very picky about which males they mate with. This often means extravagant features such as those found in peacocks. Or in many mammals, strong, healthy, hard-working, and faithful males.

To paraphrase Richard Dawkins in "The Selfish Gene", the evolutionary hypothesis for the origin of biological gender is as follows:

Perhaps one organism decided to reduce the amount of investment he put into a single offspring and instead aimed for quantity as opposed to quality. Conversely, other organisms compensated the lack of investment from their mates by increasing their relative investment to ensure that their offspring would make it. This in turn allows the slackers to slack off even more... Over time this becomes a positive feedback loop that leaves us with two sexes.

[lajoswinkler]

Absolutely possible and probable as it increases genetical diversity. There are multiple sexual systems on Earth, not just the ones we're most familiar with, so I'm sure such systems would evolve elsewhere. Plants, animals, bacteria... Sexual reproductions keeps life stronger.

[Malokin]

Alot of wild assumptions have been made in this thread.

1. Independent life would not necessarily be DNA based.

Unless these other organisms are our panspermian cousins, it is unlikely that other organism would have DNA at all. They most likely would not even be cellular. I only say "most likely" because the quasi random nature of evolution means that different life will respond to challenges, it is unlikely they will use the EXACT SAME mechanisms to deal with those challenges. (evolution was a presupposition of the OP's original post, so I won't argue that this life may function without evolution at all)

2. DNA or not, sexual reproduction would not likely be a function of alien life.

Sexual reproduction assumes that this form of life replicates it self thru the exact same means we use, which would be unlikely. Perhaps other organism build copies of themselves intelligently, like a race of robots. Perhaps the organisms reproduce by simple splitting in half, the way cellular life does. Perhaps all organisms of a "species" descend from a single queen organism that does not require ... or fertilization of eggs. Perhaps other life never reproduces at all, perhaps whatever event caused the initial life to exist sometimes reoccurs, and new life is added to their "eternal" ecosystem.

3. Just because our evolutionary strategies work, does not mean that the same outcome is not achievable thru different means.

I see people arguing that sexual reproduction would be likely simple because it work to accomplish "some goal". I agree that genetic diversity and the other goals listed are an important part of evolution, I just disagree that using the exact same strategy we use is the most likely in an independent system with different operating perameters. I would argue that other roads to the same goals exist even on our own earth, and would especially exist on a world with a different set of conditions to drive said evolution.

Please remember that evolution is the only known force that can create increasing complexity out of simplicity. This likely seems counter intuitive but this is possible by taking "steps". Take what exists, add "1 step" of complexity, throw it against the wall and see if it survives, repeat. The way evolution accomplishes these goals is not necessarily the most simple or most efficient method available, and as the goals of survivability change (change in environment), an organism is "trapped" with changing what it already posses into what it needs thru evolution, fin into leg, leg into wing. A great example of this is a nerve that goes all the way down a giraffes neck, then all the way back up because evolution found it easier to just extend the neck one step at a time then to totally reinvent or rethink its own highly inefficient highway of nerves ( http://scienceblogs.com/grrlscientist/2010/06/22/the-laryngeal-nerve-of-the-gir/ WARNING: Video may contain Richard Dawkins). You have the chance now, with your own imagination, to rethink sexual reproduction in a way evolution does not have the option of doing. You get to cut out the inefficiencies, or even add new inefficiencies into the fiction of your alien species reproductive techniques.

Edited December 11, 2014 by Malokin

[lajoswinkler]

Alot of wild assumptions have been made in this thread.

1. Independent life would not necessarily be DNA based.

Unless these other organisms are our panspermian cousins, it is unlikely that other organism would have DNA at all. They most likely would not even be cellular. I only say "most likely" because the quasi random nature of evolution means that different life will respond to challenges, it is unlikely they will use the EXACT SAME mechanisms to deal with those challenges. (evolution was a presupposition of the OP's original post, so I won't argue that this life may function without evolution at all)

2. DNA or not, sexual reproduction would not likely be a function of alien life.

Sexual reproduction assumes that this form of life replicates it self thru the exact same means we use, which would be unlikely. Perhaps other organism build copies of themselves intelligently, like a race of robots. Perhaps the organisms reproduce by simple splitting in half, the way cellular life does. Perhaps all organisms of a "species" descend from a single queen organism that does not require ... or fertilization of eggs. Perhaps other life never reproduces at all, perhaps whatever event caused the initial life to exist sometimes reoccurs, and new life is added to their "eternal" ecosystem.

3. Just because our evolutionary strategies work, does not mean that the same outcome is not achievable thru different means.

I see people arguing that sexual reproduction would be likely simple because it work to accomplish "some goal". I agree that genetic diversity and the other goals listed are an important part of evolution, I just disagree that using the exact same strategy we use is the most likely in an independent system with different operating perameters. I would argue that other roads to the same goals exist even on our own earth, and would especially exist on a world with a different set of conditions to drive said evolution.

Please remember that evolution is the only known force that can create increasing complexity out of simplicity. This likely seems counter intuitive but this is possible by taking "steps". Take what exists, add "1 step" of complexity, throw it against the wall and see if it survives, repeat. The way evolution accomplishes these goals is not necessarily the most simple or most efficient method available, and as the goals of survivability change (change in environment), an organism is "trapped" with changing what it already posses into what it needs thru evolution, fin into leg, leg into wing. A great example of this is a nerve that goes all the way down a giraffes neck, then all the way back up because evolution found it easier to just extend the neck one step at a time then to totally reinvent or rethink its own highly inefficient highway of nerves ( http://scienceblogs.com/grrlscientist/2010/06/22/the-laryngeal-nerve-of-the-gir/ WARNING: Video may contain Richard Dawkins). You have the chance now, with your own imagination, to rethink sexual reproduction in a way evolution does not have the option of doing. You get to cut out the inefficiencies, or even add new inefficiencies into the fiction of your alien species reproductive techniques.

1. There is no reason why should sexual reproduction and sexual dimorphism have to be DNA/RNA based just like having photoreceptors and motility organs.

Evolution is inevitable by its very definition and, again, not inherently linked to DNA. As long as there are mutagens, hereditary material and reproduction, there will be evolution.

2. Robots are not organic life and will not form by biological evolution, so they can't be part of any argument here.

Simple splitting without any change does exist on Earth, but it never made anything complex. We're talking about complex, evolved life, beyond procariot-like organisms. It is highly unlikely that animal-like organisms, motile and active, would behave like bacteria.

Again, you seem to forget that sexual reproduction as a concept is not tied to the base mechanisms it relies on on Earth. There could be other mechanisms and biochemistries with sexual reproduction, just like other bases could and would yield bilateral symmetry for organisms actively moving in fluids.

3. It is highly unlikely for a highly complex species to arise by cloning, where by highly unlikely I mean "for all intents and purposes impossible". If you have hereditary material, vast opportunities are presented to you if you exchange it with another organism. Reproduction by pure cloning would make your species stagnant and, if suitable methods (huge population or very powerful repairing mechanisms) don't work, a cul de sac and prone to extinction.

Think of sexual reproduction, of which there are many varieties, as expected as motility or sensitivity to touch, and not as something intrinsically tied to our genetics or biochemistry.

[RainDreamer]

So, like a certain race of monosexual blue alien that apparently reproduce by copying the genetic maps of their partners through connection of nervousness system? I wonder what the environment on their home world is like and the evolution path they took.

[LordFerret]

I wish I could remember where I'd read/heard this, so I could cite it, but I recall a discussion of the 'more likelihood' of our encountering life silicon-based... because it was the next most feasible compared to carbon-based. All had to do with molecular structure and bonding.

[RuBisCO]

Hermaphroditism is unstable, males and females tend to evolve, its about resources. As long as large amounts of resources are needed to reproduce then there will be pressure for males to evolve and cheat the system, and eventually females evolve because of the sausage party effect.

Sure if a biosphere lacks individual life forms and genetic material moved fluidly enough there would not even be sexual reproduction as we know it, like bacteria, or Kerbals. Say for example the Kerbals don't just reproduced but also trade genetics materials by shaking hands or bumping their big heads, or something, and simply modify themselves with the new genetic material before budding or doing what ever it is they do, then there is not reason for gender. It would be most fit to for everyone to be able to trade genes: being able to reproduce is now separated from being able to trade genes.

[Malokin]

2. Robots are not organic life and will not form by biological evolution, so they can't be part of any argument here.

There is no reason that organic life could not assemble more organic life out of pieces depending upon what those pieces are. I just use the word robots to explain the methodology of reproduction, not the biology or lack fo biology of the organism.

Simple splitting without any change does exist on Earth, but it never made anything complex. We're talking about complex, evolved life, beyond procariot-like organisms. It is highly unlikely that animal-like organisms, motile and active, would behave like bacteria.

Your talking about bacteria that create copies of themselves, it's possible to copies ones own DNA while introducing mutation and even keeping a sort of database of recessive genes to supply genetic diversity.

Again, you seem to forget that sexual reproduction as a concept is not tied to the base mechanisms it relies on on Earth. There could be other mechanisms and biochemistries with sexual reproduction, just like other bases could and would yield bilateral symmetry for organisms actively moving in fluids.

I don't discount that it is possible that other forms of life could use this technique, I just think that other methods are just as reliable or MORE reliable and useful for the goals and mechanisms of evolution than sexual reproduction

3. It is highly unlikely for a highly complex species to arise by cloning, where by highly unlikely I mean "for all intents and purposes impossible".

Nonsense, it is equally highly unlikely that we have arisen the way we have, yet we did AND it works. If you looked at out our biology from the outside, you'd probably question why we have liquid blood that could easily pour out and result in death, until you understood all the caveats and subsystems that make such a thing plausible and even quite effective. If you refuse to think that a self clotting system is possible, liquid blood would seem impossible and foolish for biological life. The same goes for other, non-sexual means of reproduction. Your vision of cloning and mine are not the same and I venture to guess that you could easily introduce all the qualities that necessitate evolution into your narrow view of cloning.

If you have hereditary material, vast opportunities are presented to you if you exchange it with another organism. Reproduction by pure cloning would make your species stagnant and, if suitable methods (huge population or very powerful repairing mechanisms) don't work, a cul de sac and prone to extinction.

Again, no one suggests pure cloning, but rather cloning with the introduction of variation from generation to generation either accidental or purposeful.

Think of sexual reproduction, of which there are many varieties, as expected as motility or sensitivity to touch, and not as something intrinsically tied to our genetics or biochemistry.

I certainly don't think of it that way, at least for our life it is tied to our genetics and biochemistry, but for a completley different set of non-gene genetics or biochemistry such a thing is hardly required and maybe even completely convoluted.

[lajoswinkler]

I wish I could remember where I'd read/heard this, so I could cite it, but I recall a discussion of the 'more likelihood' of our encountering life silicon-based... because it was the next most feasible compared to carbon-based. All had to do with molecular structure and bonding.

That won't happen. Silicon is a much larger atom and thus its orbitals' overlapping in compounds is poorer. Its analogues to carbon compounds are way less stable and readily decompose at much lower temperatures than carbon ones do. The element also tends to make crystalline compounds with other nonmetals which melt at very high temperatures.

All this, combined with the large availability of carbon in space, put silicon away. Carbon is not good because it's carbon. It's good because of its electronic configuration.

There is no reason that organic life could not assemble more organic life out of pieces depending upon what those pieces are. I just use the word robots to explain the methodology of reproduction, not the biology or lack fo biology of the organism.

I understand now, but you're describing asexual reproduction. If you mean construction outside body and it doesn't involve intelect (because then that can't be included in the discussion), then how did those organisms came to be in the first place? They had to evolve.

Your talking about bacteria that create copies of themselves, it's possible to copies ones own DNA while introducing mutation and even keeping a sort of database of recessive genes to supply genetic diversity.

It's a very poor genetic diversity compared to sexual reproduction. If the evolution leads to sexual reproduction, the species gains a powerful tool for even better adaptation. Vast majority of the life on Earth evolved the capability to do so. Bacteria share plasmids, plants produce motile gametes, etc. It makes the species more resilient. Chances are such behaviour would occur elsewhere because it's not keeping all the eggs in one basket. A smart thing nature made by chance.

I don't discount that it is possible that other forms of life could use this technique, I just think that other methods are just as reliable or MORE reliable and useful for the goals and mechanisms of evolution than sexual reproduction

Well, they are not. The sciences of ecology and biology disprove you.

Nonsense, it is equally highly unlikely that we have arisen the way we have, yet we did AND it works. If you looked at out our biology from the outside, you'd probably question why we have liquid blood that could easily pour out and result in death, until you understood all the caveats and subsystems that make such a thing plausible and even quite effective. If you refuse to think that a self clotting system is possible, liquid blood would seem impossible and foolish for biological life. The same goes for other, non-sexual means of reproduction. Your vision of cloning and mine are not the same and I venture to guess that you could easily introduce all the qualities that necessitate evolution into your narrow view of cloning.

On the contrary, it's not equally unlikely. Sexual reproduction offers more diversity. More diversity results in less mortality when species is exposed to a problem.

So you propose a species which is reproducing by cloning while it auto-introduces high levels of mutations to keep the gene pool different?

There's one huge problem with your idea - such species would be short lived because no hereditary information is shared between the organisms. If huge mutations are introduced every time an organism multiplies, it has a large chance of dying (most mutations must be detrimental; it has a lot to do with entropy), not to mention the divergence would be extreme so we could not have stable and numerous populations. Of course, tweaking the reproduction rate could help, but it would require a large one, and such life or biosphere if you please, would be very similar to fire or any other chemical reaction where the equilibrium is shifted greatly towards the products. It would consume its environment and then what?

I certainly don't think of it that way, at least for our life it is tied to our genetics and biochemistry, but for a completley different set of non-gene genetics or biochemistry such a thing is hardly required and maybe even completely convoluted.

I advise you to brush up on ecology. This is not genetics or biochemistry we're talking about. It's pure ecology and the system you're postulating is for most intents and purposes not sustainable.

[Malokin]

I understand now, but you're describing asexual reproduction. If you mean construction outside body and it doesn't involve intelect (because then that can't be included in the discussion), then how did those organisms came to be in the first place? They had to evolve.

I am not disputing the organisms evolution, it was a presupposition of the OP. Construction outside the body, in my mind, would be similar to the hypothesized methods of abiogenesis for cellular life, expect the forces that may have accidentally created life thru abiogenesis would be purposefully recreated and harnessed for the purposes of reproduction. The variables in this methodology would lead to diversity and changes in the "construction techniques" of these lifeforms could evolve from generation to generation.

It's a very poor genetic diversity compared to sexual reproduction. If the evolution leads to sexual reproduction, the species gains a powerful tool for even better adaptation. Vast majority of the life on Earth evolved the capability to do so. Bacteria share plasmids, plants produce motile gametes, etc. It makes the species more resilient. Chances are such behaviour would occur elsewhere because it's not keeping all the eggs in one basket. A smart thing nature made by chance.

Again, you only cite things you have observed on earth and label them as the best tool for evolution. You are making an "argument from ignorance". We're talking about how a fictional alien organism COULD biologically operate, not how earth life behaves. Other methods than sexual reproduction can achieve the same results or even possibly better evolutionary results. You're assumption that sexual reproduction is the best technique, just because it is the best on earth is completely unfounded. You think hammers are the best thing in all the universe at inserting nails into things because all we have in the shed is hammers, the OP didn't ask how biology works on earth, he asked how biology could work for alf.

Well, they are not. The sciences of ecology and biology disprove you.

Earth biology does not disprove or effect the liklihoods of creatures that are not from earth. If aliens from planet X work in a different way than you, it doesn't mean you have to operate just like the aliens from planet X, it's possible, and possibly likely that two independent methods exists for achieving the same goals.

On the contrary, it's not equally unlikely. Sexual reproduction offers more diversity. More diversity results in less mortality when species is exposed to a problem.

Sexual diversity offers better reproduction than the other techniques used here on earth. You cannot extrapolate those results and conclude that sexual reproduction is the be all end all of genetic diversity. It isn't hard to use your imagination to hypothesize improvements in genetic diversity be adding caveats to sexual reproduction, and I personally don't find it that hard to hypothesize and imagine evolutionary techniques that completely remove sexual reproduction.

So you propose a species which is reproducing by cloning while it auto-introduces high levels of mutations to keep the gene pool different?

There's one huge problem with your idea - such species would be short lived because no hereditary information is shared between the organisms. If huge mutations are introduced every time an organism multiplies, it has a large chance of dying (most mutations must be detrimental; it has a lot to do with entropy), not to mention the divergence would be extreme so we could not have stable and numerous populations. Of course, tweaking the reproduction rate could help, but it would require a large one, and such life or biosphere if you please, would be very similar to fire or any other chemical reaction where the equilibrium is shifted greatly towards the products. It would consume its environment and then what?

I never purposed HUGE mutations, I purpose a system of cloning that introduces mutation at the exact same rate that our system introduces mutation at, just without the need for sexual reproduction.

[LordFerret]

... Carbon is not good because it's carbon. It's good because of its electronic configuration. ...

This I knew. I think however the closeness to that configuration was the argument of 'the author' whose article I can't find. Sorry. :/

[kerbiloid]

Construction outside the body, in my mind, would be similar to the hypothesized methods of abiogenesis for cellular life, expect the forces that may have accidentally created life thru abiogenesis would be purposefully recreated and harnessed for the purposes of reproduction.

Life is a cyclically self-reproducing process with accumulation of information (in thermodynamical sense of it, i.e. chaos->order).

So, any life would be cellular in wide sense of "cell": an isolated space with its own in-line cyclical processes.

A mess will stay only a mess where no one process could be repeated infinitely with a competition against another such process.

So, no cell means a mess; a mess means no evolution, just an endless organic goo bubbling.

To get an evolution you would definitely split your vat to separated bubbles.

[Malokin]

Life is a cyclically self-reproducing process with accumulation of information (in thermodynamical sense of it, i.e. chaos->order).

So, any life would be cellular in wide sense of "cell": an isolated space with its own in-line cyclical processes.

A mess will stay only a mess where no one process could be repeated infinitely with a competition against another such process.

So, no cell means a mess; a mess means no evolution, just an endless organic goo bubbling.

To get an evolution you would definitely split your vat to separated bubbles.

Your talking about explanations of why our life on earth works the way it does. You've perfectly explained why our form of life works/evolved the way it does/did. But you can't leverage an understanding of our techniques for survival to disprove or judge the likelihoods of other possible solutions to the same survival problems. If you can't even imagine non-cellular alien life, you're really limiting the scope of what your idea of an alien even is.

On a planet with very little environmental pressures, the contents of our cells (the "mess" as you call it) would not necessarily need a protective covering to survive. Simple linking the organelles together on a rope might suffice. On a planet with incredibly harsh conditions, more than just the protection of a cell might be required, a much larger naturally occurring structure might be the only safe vessel for life in a very harsh environment. You can't apply the merits that our earthen cellular life has utilized to these different environments, there simply would not be any reason for life to evolve such cellular structures without the environmental pressures that our life was subject to.

[KerikBalm]

Sexual reproduction independently evolved on Earth multiple times in multiple lineages. Example: plants and animals.

You need some sort of recombination, otherwise you have no escape from a Mullerian ratchet, and the species is doomed.

http://en.wikipedia.org/wiki/Muller%27s_ratchet

Granted you don't need ... for recombination.

and ... doesn't neccessarily mean sexual reproduction either.

This cloning + mutation thing wouldn't work.

We have seen many different ways of circumventing Muller's ratchet evolve on Earth, some convergently arrive at the same solution (sexual reproduction)

It is likely that an independent genesis that leads to a diverse biosphere would also have many lineages arrive at this solution as well.

[Malokin]

Sexual reproduction independently evolved on Earth multiple times in multiple lineages. Example: plants and animals.

Your talking about 2 "independent" developments in the same planetary environment and with organisms that started with a huge amount of shared dna to begin with.

You need some sort of recombination, otherwise you have no escape from a Mullerian ratchet, and the species is doomed.

http://en.wikipedia.org/wiki/Muller%27s_ratchet

Granted you don't need ... for recombination.

and ... doesn't neccessarily mean sexual reproduction either.

Exactly! For DNA and genes to accomplish their evolutionary "goals" recombination is a wonderful toolset, and sexual reproduction is not the only road to recombination as you admit.

Perhaps a lifeform could assemble a full genetic profile by collecting a small amount of DNA from a series of "nodes" in it's environment and assembling them. These nodes would be a sort of egg filled with one particular gene that a lifeform could come and access for reproduction. Every organism that contained a certain gene would work to nourish that "node" during their life. Organism would mostly visit the nodes they had nourished during their life for reproduction but not necessarily all of them. Nodes could contain small amounts of variation, but this variation would be limited because of the small size of the genetics within them. New nodes could split-off from old nodes when enough diversity occurs, and I'm assuming mutation occurs at stable levels within the nodes, and during the creation of new nodes.

Now imagine a non cellular form of life who does not depend on DNA or the genetics within them. There are even more variances to our evolutionary techniques that could occur.

This cloning + mutation thing wouldn't work.

I disagree. At least explain why you make that assertion, and yes, I will then produce a list of possible caveats that might satisfy whatever your concerns are. Thats the difference between talking about fantasy aliens and talking about earth biology from the past/future. If you want to talk facts, the fact is there are no aliens that we know of. We are starting this conversation with bad presuppositions and following from there, and I think considering the bad presuppositions we start with (assuming aliens with evolution from planet X) you have to question the idea that these lifeforms will even have cells, you have to question if they will even have DNA. I can agree that is these aliens were our "space cousins" thru panspermia, or were the most coincidental organisms to ever exists then everything you say is true, I just think both of those are highly unlikely unless the OP adds them in as a presupposition to our discussion.

We have seen many different ways of circumventing Muller's ratchet evolve on Earth, some convergently arrive at the same solution (sexual reproduction)

It is likely that an independent genesis that leads to a diverse biosphere would also have many lineages arrive at this solution as well.

Again, the "independent" "convergent" development of sexual reproduction, as well as other convergent developments (eyes have developed "independently" over and over and over for many different organisms) are not independent at all. You forget that both plants and animals are the descendents of the same great grandmother organism. They share dna, and even though they develop new information, they can only derive that new information from variations of the old information they possess. Also, remember that all these creatures are responding to the same planetary environment, which is the driving factor of this convergence.

The idea of aliens presupposes a likely lack of cellular structure, DNA, and maybe even biology as a whole. Thats why you call them aliens, because they aren't like you, they're alien in composition and physiology. Sexual reproduction is the go to solution for cellular life who utilizes DNA for heredity. No one disputes that, I just dispute that cellular life that utilizes DNA would hardly even be worth considering an alien, more like just another "kingdom" in the biological classification system.