Extraterrestrial Life: How Similar Would It Be to Earth's Wildlife?

[zoobyshoe]

Good point Zooby... sorry I missed your first post on this thread.

With regard to the two starting points of life on a planet... abiogenisis and panspermia... I like to try and calculate the percentage of probability for each beginning of life on a planet. What are the odds for "habitable planets" to be seeded with interstellar or inter planetary viruses or megabacteria and what are the odds for the same to support the actual formation of life... from scratch?

For instance, Earth may well have been an incubator for life that simply drifted here from mars... with Mars being the site of abiogenisis... (as an hypothetical example).

Panspermia can be considered a form of mass extinction: all life forms that did not get ejected into space and survive are effectively extinct as far as the new environment is concerned. This throws a twist into the game: in the new environment the life will evolve differently than it would have on the home planet, not only because the environment is different, but because all it's competitors and symbiotes are gone.

As for probabilities, I have the feeling that moving from chemical to life must needs be probable. It's hard to believe it is so delicate that it only happened on one planet and spread to the rest (assuming there is, or has been, life elsewhere). Perhaps there is some strain of primitive bacteria or mold or algae or whatever so ubiquitous no one is surprised to find it in the soil here any where on earth, but, in fact, it has been generated from scratch during the last lightning storm. In other words, perhaps abiogenesis is ongoing and chronic. However, that could be ignorant raving. I'm not sure. Someone might be able to easily explain why that's impossible.

 

[DaveC426913]

I agree with that as well, and in fact I'm in you camp when it comes to belief that while carbon based life is possible, so is life based on other chemistry. The nature of their primary, their orbit, and initial conditions for life would be VERY critical. If life based on our scaffolding can't exist on a given planet, but another chemistry COULD dominate, not having to compete with ours changes matters.

This argument presupposes that there are alternate possibilities for complex chemistry / life.

But are there?

We have access to all elements here on Earth under controlled and uncontrolled conditions, and what we see is that there are precious few combinations that can (let alone might) form very complex molecules. It just doesn't happen.

Question: what is the most complex non-organic molecule known?

 

[jackmell]

I do not see a problem with abiogenisis at all and feel panspermia is unlikely unless it "rained" down continuously for thousands of years. Given a sufficiently complex chemical mixture, time, and energy, "complexification" emerges naturally. That's what I believe and is proposed by Stuart Kauffman and John Casti in the books "At Home in the Universe" and "Complexification". Two other, "Signs of Life" and my all-time-favorite, "Self-Organization in Biological Systems" convince me that life is inevitable. I believe anyone that reads those four books would find final comfort in the matter of how life may have arose on this planet starting from simple chemicals. That's what happen to me. :)

 

[Shalashaska]

This argument presupposes that there are alternate possibilities for complex chemistry / life.

But are there?

We have access to all elements here on Earth under controlled and uncontrolled conditions, and what we see is that there are precious few combinations that can (let alone might) form very complex molecules. It just doesn't happen.

Question: what is the most complex non-organic molecule known?

I don't know without using Google regarding your question, so I won't insult you with a random guess. That being said, Nitrogen, Chlorine, Sulphur, Arsenic, Phosphorus, Methane, Silicon/Silanes and more are all viable in roles that replace carbon. Given the limited scope of our "laboratory" and ongoing discoveries about the synergistic role of plants and bacteria, fungi and bacteria, and human's and viruses (which are organic, but alive?), I tend not to assume that we have a lock on biochemistry.

Question: How many different combinations does it take, especially if Planet 'B' is never hospitable to carbon-based life, and therefore P-N types never have to compete in that arena? Hell, for all I know you could have a form of life based on electromagnetic interactions within rock formations in a planet close enough to its primary. I don't really see that as likley, and I wonder if that would be life or just a thermodynamic system, but then I wonder if we're equipped to know the difference in enough cases? We have access to elements, but the conditions in which we find them and manipulate them are limited by our technology (after we have a chem lab on Venus, Mars, and Titan I'll be more inclined) and scale.

 

[zomgwtf]

P-N is also known to form rings and chains I'm pretty sure.

 

[Shalashaska]

P-N is also known to form rings and chains I'm pretty sure.

Absolutely, you get silanes and arsenides for one.

 

[baywax]

I do not see a problem with abiogenisis at all and feel panspermia is unlikely unless it "rained" down continuously for thousands of years. Given a sufficiently complex chemical mixture, time, and energy, "complexification" emerges naturally. That's what I believe and is proposed by Stuart Kauffman and John Casti in the books "At Home in the Universe" and "Complexification". Two other, "Signs of Life" and my all-time-favorite, "Self-Organization in Biological Systems" convince me that life is inevitable. I believe anyone that reads those four books would find final comfort in the matter of how life may have arose on this planet starting from simple chemicals. That's what happen to me. :)

I'll keep those authors in mind. Thanks.

I had no idea proteins were hydrophobic.

 

[baywax]

Here's a new hybrid species right on our planet...

The Polar/Griz Bear...

ULUKHAKTOK, N.W.T. - Researchers in the Northwest Territories say they may have found the first recorded case of a second-generation hybrid polar-grizzly bear in the wild, but an expert says it's not clear what the significance may be.

Government officials in the Northwest Territories said a hunter, David Kuptana, shot an unusual-looking bear during a hunting trip April 8 near Banks Island, in the Inuvik region.

He provided federal scientists with samples to see what type of bear it was.

Officials with the territorial government said those tests showed the dead bear was a hybrid — the offspring of a female hybrid polar-grizzly mix who had mated with a male grizzly.

Scientists confirmed this by comparing the dead bear's DNA with that of local polar bear and grizzly populations, and that of a male polar-grizzly hybrid, which was shot on Banks Island in 2006.

http://ca.news.yahoo.com/s/capress/100501/science/science_hybrid_bear_shot

 

[Shalashaska]

Here's a new hybrid species right on our planet...

The Polar/Griz Bear...



http://ca.news.yahoo.com/s/capress/100501/science/science_hybrid_bear_shot

Wow. That... is... wow.

 

[zomgwtf]

Wow. That... is... wow.

An ugly bear?

Yes I agree.

 

[Shalashaska]

An ugly bear?

Yes I agree.

A REALLY ugly bear! Yech, I've seen prettier chimeric mice.

 

[baywax]

A REALLY ugly bear! Yech, I've seen prettier chimeric mice.

Yes but, this is a test for anyone wishing to travel to other planets where the species may appear... um... not as you might think they should. Try to keep a poker face or even smile.... You don't know what reaction a grimace might provoke...

 

[DaveC426913]

You don't know what reaction a grimace might provoke...

If you see a Kzin smiling, you'd better be a fast runner.

A Kzin smiles, not out of amusement, but to bare its fangs.

 

[baywax]

If you see a Kzin smiling, you'd better be a fast runner.

A Kzin smiles, not out of amusement, but to bare its fangs.

So, its not a Kzin cousin?