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Are Aliens Living Among Us?
pickens writes "In recent years scientists have begun to view the existence of life outside of our solar system as ever-more likely. If life does emerge readily under terrestrial conditions, then perhaps it formed many times on our home planet. To pursue this tantalizing possibility, scientists have begun searching deserts, lakes and caverns for evidence of earth-bound 'alien' life-forms, organisms that would differ fundamentally from all known living creatures because they arose independently. Microbes have already been found inhabiting extreme environments ranging from scalding volcanic vents to the dry valleys of Antarctica. Other so-called extremophiles can survive in salt-saturated lakes, highly acidic mine tailings contaminated with metals, and the waste pools of nuclear reactors. Although 'alien' microbes might look like ordinary bacteria, their biochemistry could involve exotic amino acids or different elemental building blocks so researchers are devising tests to identify exotic microbes. If shadow life is confined to the microbial realm, it is entirely possible that scientists have overlooked it."
I think we have enough problems with ourselves, to worry about aliens living among us. As a matter of fact, what sort of superiour intelligence, which could get here, would use earth as anything other than their own Botany Bay Colony?
A feeling of having made the same mistake before: Deja Foobar
Spiders have got to be extraterrestrial. I'm just sayin' -- they are really freaky looking compared to everything else.
The headline and the article both muddily imply that the identification of life on earth fundamentally different than what we are already familiar with would, in itself, be evidence that the life was of 'alien' origin. I can't help but think this is deliberate in order to hype the story. Is there a chance that there is weird terrestrial life on earth we haven't yet discovered? Of course. Is there a chance there is alien life on earth? Yes. But which of the two would be a more likely explanation for the origin of something unusual? I think the answer is obvious, and I think it's exceedingly disingenuous to state or imply otherwise.
A-Bomb
As the article mentions, bacteria - conventional, non-alien bacteria, which share a common ancestor with other conventional life like you, me and a tree - are found everywhere on earth.
Living things are, in general, very competitive, and very effective competitors. Otherwise, they wouldn't still be here. So the odds that a new abiogenesis event, if one occurred, would produce a lifeform that would actually be viable in the face of a billion years of evolution by the competition are, I think, remote.
Also, while living things may thrive under extreme conditions (for example, in a bath of deadly oxygen gas) this does not mean that abiogenesis can occur under such conditions.
Finally, while it is true that many lab techniques are specific to detecting conventional terrestrial life, others are not. So, unless this non-conventional life is *restricted* to some remote environment - which conventional life certainly is not, so this again seems unlikely - we would be expected to have seen it.
There are some exotic coincidences which might allow for this to be true - maybe this exotic life looks just like a bacterium under the microscope, but for whatever reason cannot be cultured at all. Maybe it can't live on sugar - maybe it requires some other exotic organic nutrient which is found out in the wild but no-one has thought to add to culture medium. All possible, but also all unlikely.
Nonetheless, problems of detection of this kind remain a serious and useful direction for inquiry, in preparation for serious efforts to locate alien life on other worlds, where we will need a wide array of avenues for detection to allow for a completely-unknown level of chemical diversity.
The good and new comes from no quarter where it is looked for, and is always something different from what is expected.
Those are two different (though tangentially related) topics. Life outside of our solar system could mean anything from simple microbes, to primitive animals, to advanced intellects superior to humans. The SETI project was only looking for advanced intellects using a narrow detection scheme. One would think that a sufficiently advanced culture would advance past the use of radio waves. Especially if intra-stellar or inter-stellar communication was needed.
I think the probability of detecting intelligent life is rather low using SETI (though worth a shot). However, the possibility that life in some form exists out there is, I think, very high.
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I think you are mistaken.
.001% more nitrogen. So for billions of years, life would have evolved around this alternate condition. To assume that life would have rolled out the exact same way on the earth in this environment seems a bit of a leap.
I'm with you that we are product of our environment. But you are ignoring the implications a tiny terrestrial change would have on ALL terrestrial life.
For instance, assume the earth contained
Heck, even within our earth's periods we've seen incredibly different paths of evolution occur. What happened to the dinosaurs? Well they were here, new conditions arose, and suddenly new phenotypes are preferred. They evolved but are no longer dominant due to shifting and somewhat unpredictable conditions.
Basically I'd agree with you if Earth 2 existed and had a COMPLETE MIRROR IMAGE of our planet's history. Then we could be assured that all the variables are in sync. But what kind of odds would you give that?
Aliens could be of almost any imaginable form & traits because they could arise in almost any imaginable conditions.
Life has evolved more than once on Earth! Mitochondrian and cells were separate creatures until they formed this symbiotic relationship and out-competed both of their non-hybrid ancestors.
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