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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.
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.
Did you read it? "alien" in this context does NOT mean it came from some other place. It simply means it does not share any common ancestor with us. Even if you only read the summary you can see they are looking for "alien" life that arose hear on Earth.
Finding it means that life arose here twice (at least) and would a be revolutionary discovery. If life is common in the universe and likely to arise on any Earth-like planet then why would it not arise twice on any Earth-like planet? Or three times or 100? Science is about asking questions and this is a good question, good because it is both interesting and (maybe) possible to answer by direct observation.