Stephen Hawking recently spoke to the media regarding the existence of extra-terrestrial intelligent beings and why we as humans would be wise to avoid contact with them: according to Hawking, these beings could have the same impact upon us as Columbus did when he first visited the New World. Does this mean that aliens would obliterate us through the use of some high powered weapons which we would not be able to compete against? Not necessarily. What it does mean is this: that the aliens might bring some unknown disease with them that we have no immunity to, no knowledge of, and could die as the result of contact with the aliens.
This may seem far fetched, but that is exactly what happened when the first Europeans decided to settle the North American continent: smallpox, the flu, the bubonic plague, and pneumonia. That is quite a variety of diseases to bring to a new continent, a people such as the Native Americans who had no knowledge of the diseases – and the natives were far from ignorant in using herbal remedies to contend with known diseases – who eventually died in droves. Since Native Americans had no immunity to the diseases introduced to them, they died. While historical experts remain doubtful that the settlers deliberately infected the natives, there was no sanitation in those days where the water and land could be purified through a filter. Imagine this on a larger scale, where a planet replaces a continent, and a traveling race of aliens are seeking a new home that is sustainable to their life form. In the event an alien race did have the means to travel light years to our planet, a race that may very well resemble people like us, though with a slightly different genetic makeup that allows them to live twice as long as us, how would we respond, if we could, to something this devastating?
Provided by the time we do come in contact with aliens, our medicine might provide some kid of defense against an unknown, deadly disease. Or we might mutate as a species that will boost our immune system (think nuclear fallout). Or we could communicate with the aliens, if they are civilized enough and do not think Earthlings to be too far beneath us, and give us some kind of medication to heal us (Like Klaatu’s salve in “The Day the Earth Stood Still”). While the thought alone of making contact with aliens may excite us and NASA, something like this is important enough to keep in mind, a possible serious consequence of proving that intelligent life in space does exist.
http://news.yahoo.com/s/afp/20100425/sc_afp/scienceastronomyextraterrestrialhawking