In sci-fi books and movies, aliens are continually trying to conquer our planet. But this question is seldom, if ever, answered: why would beings from a distant, advanced civilization go to the expense and effort of journeying to Earth to mount an invasion? After all, Earthlike rocky planets are relatively common on the universe—scientists estimate that as many as 30 percent of sun-like stars have them, and the Milky Way alone, by various estimates has between 50 million and 10 billion Earth-like planets situated in the so-called “Goldilocks Zone” of their stars, in which temperatures are sufficiently moderate for life-sustaining water to exist in liquid form. (Here’s an interesting analysis of the so-called Drake Equation.) And our particular planet, as you may have noticed, is the worse for wear, after centuries of humans killing off other species, deforesting vast swaths of the continents, and pumping such astonishing quantities of pollutants into the atmosphere that they’re rapidly altering the climate. If an alien civilization is sufficiently advanced to travel here from another star system, surely they could find a planet to invade that’s still under warranty.

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So if aliens ever are going to invade Earth, they’ll need a pretty good reason. Our feverish, paranoid brains have dreamed up 10 likely possibilities.

1.    Earth has some unique resource that they can’t find closer to home.  Who knows, maybe scandium, a mineral used to make aerospace components, is rare elsewhere in the cosmos. We’ve wiped out civilizations for less.  

2.    They want to prevent a mass extinction of other species. Maybe extraterrestrials see us as the equivalent of the yellow crazy ant, an invasive species that is wiping out Easter Island’s red crabs. Whales, dolphins and butterflies are a lot cuter than humans, you must admit.

3.    They want to enslave or domesticate us. Reality TV contestants notwithstanding, there’s ample evidence that humans can be productive, with the right motivation and guidance. We might make excellent pets, as well.

4.    They want us for food.  There’s genetic and physical evidence that our ancient ancestors were cannibalistic, so human flesh apparently has some nutritional value. The Earth’s burgeoning human population has the potential to provide billions of meals to Aliens, just like some hamburger chain whose name we won’t mention.

5.    They want our DNA. There are numerous sections of the human genome whose function is unclear. It could be that some of these genes might have some value if transplanted into an extraterrestrial species.

6.    They want to wipe us out because they’re afraid of us. Humans are small and physically puny compared to many other terrestrial species, but they make up for it  with their prehensile thumbs, highly-developed intellects, and propensity for brutal violence. If aliens learn of our lengthy history of wars and violent crime, they might decide that it’s prudent to eradicate us before we develop the technology to project our animus on an interstellar scale.

7.    Earth is in the way. We seem to remember that in Douglas Adams’ A Hitchhiker’s Guide to the Galaxy, our planet was demolished to make way for an interstellar expressway.  

8.    They want to test their weaponry. Remember that in 1937, German bombers destroyed the Spanish town of Guernica not so much to help the Spanish fascist cause, but as a preparation for a future war against the French, British and Americans. Maybe the aliens want to see how well their heat ray guns work in a real situation.

9.    They want revenge. Some have speculated that life on Earth is the result of ancient seeding by some extraterrestrial civilization. It’s not inconceivable that some rival bunch of aliens might hold a grunge against us as a result.

10.  For amusement. Humans’ capacity for senseless cruelty toward vulnerable species is well-established. As the Greek poet Bion noted in 100 BC, “Though boys throw stones at frogs for sport, the frogs do not die in sport, but in earnest.” It could be that to some alien species, we’re the equivalent of those frogs.

For more, be sure to tune in to When Aliens Attack this Sunday at 8P et/pt.

Comments

  1. Dr. Dimension
    May 23, 2011, 7:21 am

    Your reasoning is almost valid. It just has no historical underpinnings. We threw everything we had at the craft hovering over L.A. back in 1942, and (a)they did not shoot back (b)we did not prevail–they left-(recent experiments prove it was there). We can ignore history and continue speculating in bloodlust.
    You can fabricate a lot of fear-mongering if you don’t look at the facts. There are aliens, (thanks for considering that)and in spite of our history of trying to screw them in a power play, they have done nothing to us at a time when they should have…when nukes were in their infancy. Go back even further, and you will see that they have been noted throughout history, and they have always been benign. Ask Travis Walton. Hollywood took his story of healing and cooperation and turned it into a horror story. We won’t have too long to wait, I think. We can only hope the U.S. hasn’t developed weapons to equal them, because they aren’t going to let us continue warping the fabric of time-space with nuclear explosions.
    Then, there’s ten years of the Phoenix lights without incident from the craft….and no USAF response. What do they know? A lot of the wrong things are being said, but none of the right things. This show is pure propaganda.

  2. RON HARMAN
    MI ... USA
    March 6, 2012, 2:04 pm

    “THEY” ARE WATCHING US FOR SOME REASON … WHATEVER THE REASON IS? WHO KNOWS BUT THEY’VE BEEN WATCHING US FOR 1000′S OF YEARS.

    LONG BEFORE MAN CAME TO BE!!!!

  3. Don't Spaz out Ron
    On a U.F.O
    January 2, 2013, 1:29 am

    if they have been watching us long before Man came to be then how where they watching us???

  4. derek
    May 15, 2013, 2:02 pm

    area 51

  5. ER
    USA
    June 14, 2013, 2:50 pm

    I’d say one good reason might have little to do with humans. The aliens could be at war with some other species and earth might just become strategically important. Also humans have proven to be adaptable warriors with a huge population. Properly trained and armed we could be made into the perfect disposable soldiers.

  6. GypsyJewel
    USA
    January 2, 9:45 pm

    Well watched to show and it was really good & insightful. Unfortunately when i heard the presidents voice I knew with out a doubt that this was truly science fiction B rated. You see what he would have said first was “Where is my teleprompter”, followed by, “The aliens have assured me that if you turn in your weapons that they will give us the cures to all major diseases”. What he fails to realize is that one of those diseases is “LIFE”. :) and then we would lose.

  7. Bull it
    Netherlands
    May 9, 6:06 pm

    It’s unknown!

    - Couldn’t it be, that it’s them who colonized the human on
    earth.
    - if they were so advanced and also different habitable planets
    The have a NATO sort of agenda or code to not interfere with
    uninvolved planets
    - who not to say that the human race issent the first intelligence
    race to invade. Cause who ever knew we could fly airplane
    - and we probley never make it that far.
    Mother Nature extinct the human race as it did with the Dino’s

    We just don’t know, or if it ever come that far

    “The truth is out there”

  8. What Is The Earth Worth? | TLEG
    August 29, 9:35 am

    […] Nat Geo list of reasons Earth might be useful to other life forms: http://tvblogs.nationalgeographic.com/2011/05/19/10-reasons-why-aliens-would-attack-earth/ […]

  9. Zorbledork Tindunglehung
    Earth
    August 30, 3:12 pm

    You’re all deluded. We have landed and we only wanted some peanut butter cups. We’ll be leaving again soon so you can go back to your boring lives stranded on this planet. Good day to you, Earthlings.

  10. MiskyWilkshake
    Earth
    September 4, 1:37 am

    Point 1 is possible but unlikely. By all accounts Earth and our solar-system are not particularly unusual or unusually formed, there’s little evidence to suggest an abundance of anything in our solar-system that would be so rare as to necessitate interstellar travel to find.

    Two (while also possible) seems equally unlikely. There’s no reason to believe that aliens should have had any prior contact with any Earthling species – as such, there’s no reason to suspect any prior bias between species. While it’s difficult to speculate on the values of alien lifeforms, if they operate by any remotely familiar logic, then from a scientific viewpoint, humans are the most interesting and potentially communicable species on our planet.

    3 again seems possible but unlikely. Unless Earth is the only inhabited planet within the reach of alien life-forms, it’s likely that any species with the capacity for interstellar travel has it’s pick of lesser races to choose from when it comes to slaves and/or pets. Given the relative mediocrity of both our planet and solar-system, it seems unlikely we’d be first picked (just think, in terms of physical labour, we’re next to useless, and not only would we likely be out-performed by creatures in say… a more massive planet with greater gravitational force, but likely by many species already living on our planet such as horses and oxen – in terms of mental and or technological labour, we’re likely so vastly surpassed by any species that’s capable of interstellar travel that we’d be of absolutely no use).

    4 seems preposterous. The human body (like our planet and indeed solar-system) isn’t particularly special in any way. It’s made up much the same stuff as most other living organisms on our planet (and as far as our understanding of potential evolutionary routes towards what we understand as life goes, likely not too dissimilar stuff as would inhabit the lifeforms of most populated planets). It seems likely to me that any lifeform to which interstellar travel is trivial enough an endeavour to undertake for very slight variations in your meal would probably have evolved or developed through technology alternate means of nourishment (say, photosynthesis for example). This is just speculation, granted – but the logistics of an evolutionary tract which necessitated interstellar travel to ensure a stable food-source ever getting off the ground is pretty unfathomable.

    5 Seems possible, though I do have to interject that DNA alteration, splicing, etc are already within the scope of human technology – I’d wager that any race capable of interstellar travel would have little trouble creating DNA without stealing data from a host (though, I must admit, I have little to back this up: I’m no geneticist, and don’t have a clue as to exactly the difficulties involved in that, nor can I presume to predict the evolution of alien technology).

    6 Seems utterly impossible. I don’t see how a species which has barely left it’s own planet let alone it’s own solar-system and galaxy could be seen as a threat to any species that has. Likely, any species capable if interstellar (or indeed intergalactic) travel would view humanity as barely sentient, let alone dangerously intelligent.

    7 seems the most implausible of the list for the simple matter of just how big and empty space is. To quote Douglas Adams, “Space is big. You just won’t believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space.”

    8 is possible, though frankly, since their weaponry is likely designed for use either against their own species, or species which pose a threat, it’s likely that testing it on a race such as ours would be of little value. We don’t go out of our way to test nuclear weaponry on ants and germs – granted, some ants and germs get killed during our weaponry tests, but I refer back to point 5 – space is big; much bigger than our measly little planet, and there’s a lot less chance of collateral damage, unless the scale of the weaponry we are talking about is enough to wipe out entire galaxies.

    9 is preposterous pandering to conspiracy theorists and not even worthy of response or consideration.

    Frankly, number 10 seems the most likely to me, given just how inconsequential the human race (or indeed all the races on our planet) would likely seem to any race capable of traveling to and destroying Earth.

  11. Ash
    India
    September 18, 11:10 am

    That absolutely rite……bt as shown in the film”independence”….aliens had already invaded………if they did ……can they be defeated by,the so called,our technolgy……..