Extraterrestrial or Ex-Terrestrial?

[aguy2]

Have you ever heard of a concept called 'panspermia'? http://mv.lycaeum.org/mu/_panspermia.html

Basically it is saying there is good possibility that life propagates itself throughout the universe by means of spores. There seems to be an unvoiced assumption that Terra is solely an importer of these spores and takes little notice of Terra as an exporter of spores.

There is a very high probability that Terra's life forms have been capable of propagating at least bacterial spores for up to three billion years. The universe may be only twelve or so billion years old, and it takes at least a second generstion star to support the heavy elements necessary for biological systems. It is relatively unlikely that spore producing organisms could have existed at a significantly earler time anywhere in the universe.

I think that there is a reasonable possibility that the sort of 'yeasty/mushroomy' critters the UFO people call 'Greys' might represent a re-immigration of terrestrial life that may have been evolving independently within the competition free environs of the comet filled outer reaches of our solar system.

Aguy2

 

[The Evelyonian]

Interesting theory.

I've heard one similar to it saying that Extraterrestrials planted life on Earth millions of years ago and there showing up to check on our progress. Both interesting. Both possible.

 

[btimsah]

I heard that flying saucers for the most part are their "probes" sending them back data, and perhaps pictures.

Fascinating to think about, because we are doing the same thing. Though NASA would hide evidence of intelligent life.

 

[Avatar]

Though NASA would hide evidence of intelligent life.

Bollox! It has no reasons to. We've discussed this prev.

 

[SkinWalker]

I've heard one similar to it saying that Extraterrestrials planted life on Earth millions of years ago and there showing up to check on our progress. Both interesting. Both possible.

Both interesting in the context of a good science fiction novel... both possible... neither very probable compared to other possibilities.

That life emerged from the chemical reaction of electricity (in the form of lightening) and simple hydrogen-rich molecules of the primitive atmosphere (hydrogen, methane, water, ammonia, and a few others) has been demonstrated in laboratory experiments (Miller, 1974) at Cornell University. They demonstrated that the early amino acids and RNA needed to begin more complex structures could, in all probability, have emerged with the conditions that were present between 4.0 and 4.6 billion years ago.

There have been no experiments that demonstrate the viability of "alien spores" surviving in space, though that certainly doesn't rule out the possibility. What I would point out is that if such things were at all probable enough to occur with the frequency and quantity needed to propagate a species of organism throughout the galaxy, it should be a common enough occurance to have observed by now. We can measure and observe nutrinos, but not spores, which are millions of times larger?

As to the hypothesis that some alien race propagating life on Earth then returning periodically to see how things are going, I again have to say this is very improbable. It implies that our DNA is compatible with some alien race's DNA (assuming that they have it), both of which evolved in totally different contexts. The suggestion is often made that aliens "implanted" early primates with some "advanced DNA" that allowed them to make the "jump" in intelligence and evolution to create humanity.

This is preposterous for several reasons: 1) these primates would have been closer matched to dafodils or field mice than an alien regardless of intelligence because of the similarities in DNA; 2) there are some very clear representation in the fossil record of a gradual evolution of primates from early shrew-like mammals to modern humanity with species such as australopithecines near the upper end of the evolutionary tree.

Aliens, either intelligent or mushroom, aren't needed in the evolutionary spectrum of life on the planet Earth.

That's not to say that some bacteria or other simple organisms haven't made their way here from places such as Mars or Titan via comet or asteriod impacts... They just aren't required to explain the advent of life on the planet.

 

[Jolly Rodger]

This is a realpicture of a UFO and Something Eles?????

 

[Ophiolite]

There have been no experiments that demonstrate the viability of "alien spores" surviving in space, though that certainly doesn't rule out the possibility.

Not true. For example,
Horneck G, Rettberg P, Reitz G, Wehner J, Eschweiler U, Strauch K, Panitz C, Starke V, Baumstark-Khan C. Protection of bacterial spores in space, a contribution to the discussion on Panspermia. Orig Life Evol Biosph 2001, 31(6):527-47

What I would point out is that if such things were at all probable enough to occur with the frequency and quantity needed to propagate a species of organism throughout the galaxy, it should be a common enough occurance to have observed by now. We can measure and observe nutrinos, but not spores, which are millions of times larger?

Two points:
Several events that were perhaps necessary to the origin or to the evolution of life were single or rare events. (Examples supplied on request. )The dispersion and delivery of spores may fall into this category.
You generally only find what you look for.

As to the hypothesis that some alien race propagating life on Earth then returning periodically to see how things are going, I again have to say this is very improbable. It implies that our DNA is compatible with some alien race's DNA (assuming that they have it), both of which evolved in totally different contexts.

Now you are being unusually illogical. If aliens seeded life on Earth they likely did so with DNA based on their own biota: therefore compatibility would be expected.

They just aren't required to explain the advent of life on the planet.

That is contingent on us delineating a plausible sequence of abiotic creation, in detail. Something that has not been done yet.

 

[SkinWalker]

Not true. For example,
Horneck G, Rettberg P, Reitz G, Wehner J, Eschweiler U, Strauch K, Panitz C, Starke V, Baumstark-Khan C. Protection of bacterial spores in space, a contribution to the discussion on Panspermia. Orig Life Evol Biosph 2001, 31(6):527-47

Then I stand corrected . Still, I maintain that if such spores were prolific enough to "seed the galaxy," then we should still have some viable evidence of their existance to a degree at least as common as nutrinos. Otherwise, the possibility is remote enough to discount alltogether since there are better, more tenable, hypotheses.

Now you are being unusually illogical. If aliens seeded life on Earth they likely did so with DNA based on their own biota: therefore compatibility would be expected.

Actually, I did consider that, and I momentarily debated covering it here, but either dismissed it or forgot as I was typing. To that point, however, I would apply the same proliferation frequency problem as I did the "spores." I'd also point out that the nucleotides present in Earth DNA have everything in common with the dominant chemicals on the planet, namely carbon/hydrogen based molecules.

That doesn't rule out off-world intervention, but it certainly doesn't exclude it. Indeed, homebrewed origin of life is a far more tenable hypothesis than an alien influenced one.

That is contingent on us delineating a plausible sequence of abiotic creation, in detail. Something that has not been done yet.

True, but there have been some very plausible hypotheses on how, Dawkins reviews an updated version of the Cornell experiment (Miller & Orgel, 1974) in at least two of his works, The Selfish Gene (1999, pp. 12-20) for instance. Perhaps better observation and even experimentation with Titan will shed some light on the subject.

References: (including the one I forgot to cite two posts up or so)

Dawkins, Richard (1976 [1999]). The Selfish Gene. Oxford University Press.

Miller, S.L. and Orgel, L. (1974). The Origins of Life on Earth. New Jersey: Prentice Hall.

 

[SkinWalker]

I just read Horneck et al, and they state on page 544, "However, single spores or spores attached to micron-sized grains, as requested by the theory of Panspermia, will not survive in space." I'd say they are in agreement with me

It seems intuitive that relatively large ejecta can shield endospores, but at the size that the theory of panspermia is suggesting, the endospores will quickly succomb to radiation and extreme temperatures.

Fun stuff, nontheless.

 

[Ophiolite]

I don't have time to present a fully reasoned and supported argument right now, but here are a suite of connected thoughts.

Dawkins explanations are not detailed to the extent that they can be experimentally tested.
In one year/ten years/sometime we may establish that the odds of chance development of life though finite, are very high.
If we postulate life developing within interstellar gas clouds we increase our available number of 'experiments' by many orders of magnitude compared with a single planet origin.

On a related topic, there is some interesting recent work (again, sorry, no references) where polypeptides, the basis of proteins, were formed by impact of ice laced with amino acids at velocities comparable with earth impact.