Thread: Life on other planets...

do you think other life would be similar to earth's life? physically i can see things being very different, four arms, squishy tentacles... you get the idea. but biochemically. since the same elements would be present, do you think similar biochemical reactions would take place?

Would aliens breath O2/ CO2...or maybe something crazy like CH4?
Photosynthesis or something else?
etc etc

I think it is funny how you still assumed carbon would be the main source of energy!

If I had to guess, I would say it would use H2 as an energy source and Si as the main structural molecule. It is so hard to say though.

IMO i think that they would indeed look something like us. I base this on my knowledge that for life to exsist there has to be a certain level of constrainment on the parameters of the planet they these "things" live on. It cant be to hot and it cant be to cold, it would have to be an earth like planet, so since the same molecules that we have on earth would be under the same "pressures" on this new planet the resulting organisms would have to look something like we have on earth... we do have squids on earth so it might look like a squid, who knows.

the most likely planet would be mars?

source and Si as the main structural molecule.

its possible but unlikly with Si since it isnt good for life but it is possible. i´ll give all possible life backbone atoms:
N
P/N
S
C
Si
they can all support life (theoreticly) P needs N to be stable enough thou

the parameters for life to exist are being stretched...

We have found cells and multicellular life that live and thrive in vents on the ocean floor which greatly exceed any temperature seen on the surface (I wanna say 500C but don't quote me on that)...

Plus we have found cells and multicellular life (very similar) that live and thrive in "cold seeps" where methane comes out of the ocean floor at really cold temperatures...

Both of those are without sunlight under extreme pressure...

Not to mention the things on the surface of the earth which live at "normal" pressure and outrageous temperatures--the things that live in geysers and on ice shelves...

Indeed, the more we look around teh more we notice that life is very hardy and, from what we have seen, can take anything that the earth can throw at it so far (with the exception of being frozen solid [though there have been mechanisms found which allow organisms to live in sub-0 temperatures for their entire lives] and being in the middle of a volcanic eruption though life can live through that but it doesn't thrive or develop in that condition that we know of yet)...

You underestimate the cunning of nature!

--Ajain

I think ideas on Si-based life are nothing more than fanciful science-fiction. Silicon shares very few of the properties of carbon which make it so versatile for life. For a start CO2 is a gas which plants fix into carbohydrates, SiO2 is a solid (sand!), how are species supposed to fix Si into biomolecules!?

The biggest argument against Silicon-based life is earth itself, it is silicon-rich and carbon-poor. So why the heck dont we have Silicon-based life???

My thoughts are that biochemically we would find that all life is based on nucleic acids and protein. These molecules are just too damn perfect at what they do and their building blocks appear to be formed quite readily even in the absence of life.

Although I think all life will be nucleic acids and protein, that is where the similarities will end. Billions of years of chance mutations and random selection pressures have shaped the way we are. These conditions could never be replicated on another planet. I think that the many forms that alien life may have taken are beyond our imagination.

if carbon life forms were on other planets, how similar would they be to us? If theres higher concentrates of oxygen, surely they would be larger, then theres the gravity they would be living with, heat etc


Also on this planet for us to look like we do comes down to the 2% of life that made it through the mass extinction of the Permian period. would we have looked different if a different 2% made it

i would consider zelos's element list a accurate one.

as for biochemical/structure, living conditions ect would all depend on how they evolved. i would assume they would follow the same "evolution rules", so we cannot possiblely be sure just how they would live. a bag of supprises!

for example as mammels, we had to develope the complex reactions inside before we decided to grow hair/feathers to keep the excess heat in.

look at the basics , but not what happens after that first moment... ?

my list is theoretical backbone elements for life.
Silicon have propeties that is more advantagues than carbons, but also some drawbacks(suicha s what u said) but that life dont necciserly need to use oxygen. Chlorine can be used instant of oxygen, some form of flour could aswell (not pure flour thou) there are many ways life can exist, im acctualy doing a project about this in school

I think life on other planets would tend to be similar at the most fundamental level, amino acids. They might build different proteins - a differing genetic code, a different energy carrier and perhaps different symbiotic relationships within the cell membranes. If all life has one common ancestor then perhaps there would be more similarities, but I don't see how panspermia could account for displacing life outside of a single solar system. I think that there would be similarities with life on Mars or another planet/moon in our solar system, but as you got further away things would get more and more different.

What's to say things would even have DNA or amino acids? Couldn't they create something completely different, something not even imagined on earth? Those creatures at the bottom of the ocean live off of sulfides that shoot through super-hot vents. entire food webs are based on organisms who can harvest sulfildes, which is something most people wouldn't think possible. More interestingly, these foodwebs are not powered directly by the sun, as all the other ones(most) are on the planet.

What's to say things would even have DNA or amino acids?

i agree with both of you. Life would require something simular to DNA and aminoacids to work but it doesnt have to look anything like we are used to it to look like. But the basic principles of aminoacids and DNA has to be in all life, something to store information and something to execute the information

I would imagine that some kind of information carrier would be needed, DNA fulfills this role for us on earth but you could invisage a different chemical system that has evolved to suit the needs of a different environment working elsewhere.

Astrobiology is a subject that we are still very ignorant to, we need to find life elsewhere before the picture can unfold, the rest is just hear say.

i agree with you billiard. without those main parts life wont exist

i think that another live-supporting planet might have whole different types of atoms, ones we havent heard of.

Originally Posted by chamilton333

i think that another live-supporting planet might have whole different types of atoms, ones we havent heard of.

I doubt it somehow unless the properties of subatomic particles vary under a different gravitational regime......... I know f*** all about quantum phenomena, but from the astronomical studies I believe that stars show consistency where atoms are concerned.

That's just about the stupidest thing I've ever heard!!! Different types of atoms, molecules maybe, but atoms cannot exactly manipulate themselves (naturally).

I believe any difference in physical appearances would need to be studied on a molecular level and we would want to see how their systems and processes work (respiration, circulation, sensory perception, expression). Ultimately the environment and its effects on the lifeform over thousands or millions of years would ultimately shape the species. I think any planet with any sort of fluids with properties similar to water on a Earthlike world would contain similar lifeforms as our own including animals, plants, bacteria and all other groups and species known on our planet.

I think it is possible for there to be humanoids in this galaxy at some evolutionay level in their existence, but the odds of them being close to our solar system is extemely low and the odds get worse as you move further and further away from Earth.

The fact that we are still discovering orbitals in our galaxy and demoting a plantet's status as a planet, shows how undeveloped we are and how we have a long way to go before we can find other lifeforms in the universe.

i would say everything is possible...

Creatures should be able to manipulate atoms themselves, but i would say the most probable in this view will be a combination of carbon and silicon. But, with the manipulation and all, they would be able to make isotopes (none radioactive ones) with different abilities. Like hydrogen holding iodine together, this all with a silicon/carbon shell and hydroxide molecules on the ends.

Metals would be a point as well, titanium would make an excelent structural buildup. Lighter than calciumcarbonate we have now (i thought we had at least). Fluoride can be used in our teeth, but why just there..... ??

The most probable form of life on other planets will be primitive. It must have all parts of the food chain. so Microscopic creatures to coldblooded and maybe even warmblooded. Most probable to find on other planets will be mice, roaches, ants, bee's, small reptiles... these won't be very different on other planets. The thing is, the bigger animals. The bigger the creature, the more vatiation it has, and the more the buildup may vary.

Still. expect everything... we don't know anything to say "that's impossible" to yet..

Originally Posted by billiards

I would imagine that some kind of information carrier would be needed, DNA fulfills this role for us on earth but you could invisage a different chemical system that has evolved to suit the needs of a different environment working elsewhere.

As i said in my previous post the basic building blocks of proteins and nucleic acids (amino acids, five carbon sugars, purine/pyrimidine bases) form quite naturally in the absence of life. They have also been found in experiments that attempt to recreate the early conditions on earth.

If these chemicals are forming naturally in the absence of life, I think that its logical to consider that life on other planets is highly likely to be based on nucleic acids and protein. These biomolecules are just TOO damn good at what they do to be outcompeted by other potentially biochemical solutions.

This doesn't mean I'm saying the same genetic code or the same 20 amino acids will be present, the biochemistry on alien worlds is likely to evolved completely different to here on Earth. But I am HIGHLY sceptical about the evolution of alternatives to DNA/RNA/protein, they arise naturally and are too good at what they do.

Originally Posted by electricant

Originally Posted by billiards

I would imagine that some kind of information carrier would be needed, DNA fulfills this role for us on earth but you could invisage a different chemical system that has evolved to suit the needs of a different environment working elsewhere.

As i said in my previous post the basic building blocks of proteins and nucleic acids (amino acids, five carbon sugars, purine/pyrimidine bases) form quite naturally in the absence of life. They have also been found in experiments that attempt to recreate the early conditions on earth.

If these chemicals are forming naturally in the absence of life, I think that its logical to consider that life on other planets is highly likely to be based on nucleic acids and protein. These biomolecules are just TOO damn good at what they do to be outcompeted by other potentially biochemical solutions.

This doesn't mean I'm saying the same genetic code or the same 20 amino acids will be present, the biochemistry on alien worlds is likely to evolved completely different to here on Earth. But I am HIGHLY sceptical about the evolution of alternatives to DNA/RNA/protein, they arise naturally and are too good at what they do.

I agree with you about the amion acids, as Urey and Milller showed, they can synthesize abiotically. RNA and DNA would have taken a long time to evolve, perhaps they're unique to us on earth?

You have to keep an open mind, amino acids are great and we haven't seen anything else that comes close to fulfilling their role, I even said in my earlier post that I thought all life would share amino acids. However, that is not to say that there are other forms that utilize other molecules in ways that we cannot even imagine.