eew,we would have to invent some kind of super anti bug spray if those things were to steal supplies from us

I think we are misunderstanding by your use of terms, do you mean a meteorite warms up? As in meteorite, an asteroid that has entered out atmosphere? If so then yes they do heat up obviously, but how does this explain autochthonic life? Most asteroids are iron rich or silicon compound based, as for the trails of water that follow in the tail of a meteorite, I would expect that these are trace amounts as I previously stated, not enough to give life a kick start.

We must remember our argument, 'that supposedly life could start from an asteroid collision,' [paraph.] I say to you that this is nigh on impossible because any organic compound, amino acid or even RNA living on an asteroid body would cease to exist post impact, even in the initial burn up.

I must admit I kind of like the Idea that we came on the very asteroid that killed the dinosoars, however scrabtrapman seems to be right on this as any frozen life on an asteroid would either burn up or die on impact, unless bullet magnet comes and gives a scientific explanation of how it is possable for life to both exist on an asteroid and survive coming to an atmosphere than I'll have to go with scrabtrapman on this one.

Thank you, I would like to reinforce my point by suggesting that any life so well equipped to the cold, airless void would be ill suited to a sudden burst in oxygen levels and temperature.

That's not the same as being warm. Meteors approaching the sun will be warmer than when they're further away, yes, but that doesn't allow them to be warm all the time, even when they're a long distance away.

Also, you're confusing meteors with comets. Comets have large amounts of ice, whereas meteors are mostly rock. A comet's tail is not caused by the ice melting away, it is because the solar wind blows past the comet and strips ice crystals from the surface.


Scrabtrapman (and others); you're confusing the situation. Meteors don't need to be warm and any hypothetical lifeforms don't need to be pursuing active, motive, life. They could be in deep freeze until they crash land in to a warmer environment.

Ok so he meant comets, right fair enough that's sorted.

But I'm going to say something one last time, any autochthonic life on an asteroid, comet, whatever, will not survive the impact with Earth or even the burn up unless the asteroid is fantastically huge and not all of it even explodes upon impact with Terra Firma.

All that needs to survive is one single bacterium (or whatever the hypothetical lifeforms are). Given that many meteorites have remained freezing cold even after passing through the atmosphere and crashing in to the earth, I don't see it as all that unlikely.

Perhaps, but then the bacterium has to contest with the immediate onslaught of an unnatural environment and competing bacteria. I suppose you would have to factor where this hypothetical meteorite has landed as well.

Nate's right. Touching a freshly landed meteorite with bare skin will give you severe freezer burn. Wait till it warms up.

And bacterial life can survive such a journey. You know why you should not refreeze food? Bacteria which settled on it once defrost are frozen with it, and spring back to life during the second defrost and multiply.

Such journeys may have already taken place. Earth and Mars exchange material all the time. Fragments blown off of one by large impacts drift through the solar system for some time, before falling onto the other. These, and indeed, all meteorites, are most easily found in Antarctica, where they stand out in the ice. This is how all Martian rocks in human possession have been acquired, since none have been returned from Mars.

It's unlikely that alien life transported in this way would survive long, especially if it shares no common ancestry and has different biochemistry (though obviously specific details would need to be known to assert this). The same way artificial life would fare poorly against native flora, and similar to the reason that no second genesis of life has occurred. But on a suitable lifeless world, which is what we usually imagine for Panspermia, a foothold is possible.

For a more terrestrial origin of life, the role of comets and meteorites is that of primary or accessory contributor of the organic molecules from which life could arise.

So perhaps some cataclysmic event that caused a large fragment of Earth to crash into Mars could restart life over there? Surely it works both ways?

Large? I imagine a large fragment would be as cataclysmic to Mars as the original event was to the Earth. No, small fragments. I'm saying that bacteria have likely been seeded on Mars many times during our planets' shared history, and certainly recently with the probes and rovers. It doesn't appear to have taken, or at least, in no place we've looked.

One idea I have heard is that life may have started on Mars during its early and more idyllic phase of existence, and was since transmitted to Earth. But there's no real evidence is support of this over other explanations, as with all panspermia hypotheses.

I just think it's to good to be true, there would be so much life across the stars if this was the case and much of it would have to originate from somewhere. I think life started on Earth in some hot pool like in Yellowstone by simple RNA and from there it evolved.

I don't think that would be the case. Mainly because the universe is just that large, and so few places in it are even potentially habitable even to bacteria.

I'm not supporting panspermia as the actual explanation for Earth, but as a phenomenon it is entirely plausible.

Fair enough. I'm far more interested in how RNA and then DNA came about, also how chloroplasts became symbiotic with plants, did they evolve separately? Who knows.

Like mitochondria, chloroplasts have their own DNA and reproduce by themselves in the cell. And like mitochondria, they very closely resemble some prokaryotes, reproducing by binary fission and having various "cell" chemistry almost identical to bacteria and unlike the equivalents in the rest of the cell. Both appear to have descended from either blundering or adventurous prokaryotes that invaded or were eaten by the ancestral eukaryotic cell, and both cells found a way to adapt to that state. Many of the smaller cell's genes migrated into the nucleus leaving only a skeleton genome behind, and now neither can survive without the other.

Interestingly, there are several living species of single-celled organisms that represent actual intermediate steps in this process, including one that has to catch and retain cyanobacteria to serve as its chloroplasts.

This is called endosymbiotic theory, and a similar one (viral eukaryogenesis) postulates that the nucleus is derived from a large DNA virus that invaded an archaean cell and assumed total control.

You'd be so awesome as a biology teacher for sixth form!

So when someone catches a virus, it's really just the viruses taking a return on their evolutionary investment...

I'm pretty sure flagallae were another little wriggly organism that got subsumed into early prokaryotes.

a flagellum is likely to be an evolutionary accident rather than a 'fusion of two bacterium' because that doesn't make very much sense. These little cells were better at swimming than their counterparts and thus survived better.

i have heard that mars and venus were also having some early life with our planet,but venus got global warming and it went wild,and mars went cold,a rover found something looking like a petrified wood,so there was life on there probably.

I doubt it found a whole petrified wood, also trees have taken many millions of years to evolve, anything still there would be buried under sediment, however shallow.

And then got swallowed by a bigger blob and retained for the advantages they gave.

It's not provable, but it's plausible enough.

Symbiosis in Cell Evolution (Margulis, 1981) includes the proposition that endosymbiotic spirochaetes became eukaryotic flagellum and cilia, though it hasn't gained much favour since both structures lack both DNA and ultrastructural similarities to bacteria and archaea.

MM, it wouldn't have happened with the prokaryotic flagellum. I don't know of any prokaryotes that have been the larger beneficiary of endosymbiosis. Also, the bacterial flagellum is a molecular engine with rotary parts, it would be like expecting an outboard motor to sail without a boat. And the bacterial flagellum is already understood to simply be a Type III secretory and transport system (normally used to injected eukaryotic cells with toxins) with a long and large protein chain on the end of it.

That was a dickhead on the internet who spotted a rock in a photograph that looked vaguely like a stump of wood. The 'petrified wood' is not recognised as such by anyone who knows what they're talking about.

Fair enough.

No.

There could've been life a long time ago, but if we want to see life on other planets today, we would have to search dozens of light years away from our solar system.

life might be anywhere,it doesnt mean that we have to go thousands of lightyears to find life,mabe neighbouring stars harbour with life

We need to search MA's vagina, I hear there's life in them acidic enzymes he secretes.

MA's vagina is like Venus. Acidic and sulphurish.

Spoocaholic made a good point. Life may have ended elsewhere, maybe the time will come when humanity finds a terrestrial planet with no life then uncover a vast necropolis.

Anyone heard about the Mars monolith?

It's more like Jupiter. Because it's fucking massive.

The 'phobos' monolith was likely explained two years ago...either that or there really are necrons under mars trying to awaken the Void Dragon.