Ever since H.G. Wells’ masterpiece War of the Worlds made its debut, people have always been drawn to the concept of aliens invading our world. Given our history it’s easier to believe that alien visitors won’t be benevolent, which is why Stephen Hawking recently warned about trying to seek out extra-terrestrial civilizations. This fascination continues to this day as seen with TNT’s new cable series Falling Skies and recent films like Skyline, Battle: Los Angeles and Transformers: Dark of the Moon. As we watch or read about would-be world conquerors (and how intrepid humans hatch schemes to repulse the invaders), one thing comes to mind given what we know about space. Why invade us?

Let’s look at some reasons offered in books, films, and other media:

Location, location, location. The aliens’ world is dying and they need new turf to call their own and our world is best able to fit their needs. The most famous example of this was the premise of War of the Worlds. There are many things wrong about this idea. One is that it’s doubtful that our unique biosphere will be compatible with an alien species. Think of Pandora the planet in Avatar, yes it had an oxygen atmosphere but the air was toxic to humans due to the concentration of other elements, not to mention the gravity was different. These kind of problems will be faced by alien conquerors, meaning our planet in the long run isn’t suitable. In fact, at the end of Wells’ book this proves to be the case since Earth’s bacteria kill the invading Martians. The only solution is to terraform the Earth into one resembling the aliens’ habitat. Good examples of that are found in David Gerrold’s War Against the Chtorr books and in War of the Worlds.

A deeper problem arises from a military conquest angle where Earth is prized just to gain territory for an interstellar empire. Space is huge, really huge. It’s pretty hard to believe that in all that space, the aliens can’t find a world much closer to their own to occupy and/or terraform rather than spending resources to come all the way out here. The Martian invaders in Wells’ book are of course an exception to that idea when considering how close they are to us.

Slave Labor. In the current episodes of Falling Skies, Earth’s children are fitted with biomechanical devices and are forced to do manual labor for the aliens. While this premise is terrifying, especially for parents, and is a good motivator for the human heroes, again it’s not very practical. Any alien civilization that can travel such far distances would have a technology advanced enough to not need manual labor. Even today, as robotics and other technology improves, we have less and less need for manual labor. It’s easier to build machines to do our bidding rather than having to be concerned for feeding and caring for a human laborer. That’s one issue facing car makers and other manufacturers today.

Pre-emptive. Think of the rationale behind the Iraq War but applied on a galactic scale. Or better yet remember Klaatu and Gort from The Day the Earth Stood Still. An advanced alien culture is aware of our existence, keeps tabs on us to see how we’re advancing socially and technologically. If they conclude that we could become a serious threat once we achieve FTL, they may decide to fight us here instead of there. Luckily, depending on how you look at it, we haven’t advanced enough so far to constitute a cosmic shock and awe campaign.

Our Bling and Other Goodies. Let’s get one thing straightened out, any self-respecting sci-fi fan and science geek knows that all our precious metals and other materials can be easily found in space. That includes water. Yes the water we’ve found on nearby moons is frozen, but melting it isn’t a big deal. Need some H2O? Just mine any nearby comet. Heck aliens would have an easier time building a refinery on Europa and leave us alone. For all we know they may be there already. This fatally shoots down the rationale behind V and Battle: Los Angeles.

Back in May, National Geographic channel aired a special called When Aliens Attack that looked at how a plausible alien invasion would happen. In one segment the reason behind an invasion was discussed and scientists on the show pointed out the above and added that the two thing we have here that no one to date has found in the universe are proteins and chlorophyll. So in other words we’re a food or fuel source for invaders. That kind of goes with the mindset of the aliens seen in Independence Day  (which by the way, celebrates its 15th anniversary this July) who were described as a race of locust-like beings that razed planets for resources and moved on.

What about procreation? Here’s the typical premise, the alien race is dying out and their key to survival is somehow procreating with us or using our DNA to create a hybrid race. This theory is cited by UFO followers to explain cases of alien abductions. In films, this was used by Invasion of the Body Snatchers, Species and  John Carpenter’s The Thing, among others. The problem with this theory is that the idea of procreating with an alien life is impossible. Our planet’s life forms have DNA that is not in any way compatible with extra-terrestrial DNA and vice versa. Sure they may have the technology to overcome this but if they do possess such tech why not apply it much closer to their home instead of traveling thousands of light years to get cow samples? Even if they needed our unique biological makeup, aliens with such advanced technology don’t need to invade us en masse, just take some samples, replicate it and move on.

However, we may have some kind of cultural or biological attribute that may be prized by an alien civilization. The Borg in Star Trek are a good example of this mind set. They set about conquering worlds just to assimilate unique biological and technological attributes that they’ve encountered. There was an issue of Amazing Spider-Man (issues 269-270) where Spider-Man fought the alien Firelord who traveled all the way to Earth just to get some pizza and caused calamity to get it. (Can’t blame him on that account). Then again it would be a lot easier to just negotiate trade with us. It’s easy to imagine that humans would trade a year’s supply of chocolate or complete Beatles collection in exchange for FTL drives.

Predatory Culture. This could be plausible. An advanced race may be ingrained warriors or conquerors whose society is based on predation. They wiped out the game preserves near their world and are looking for easy, new or challenging pickings and that happens to be us. Maybe they’re just bored or have a sadistic streak like kids that get their jollies from terrorizing bugs in the backyard. The Klingons, and the Predators are great examples. Another motivator may be religious like the alien Covenant in the Halo games. There the aliens find humanity to be blasphemous and engage in a holy war against Earth. What could be saving us for the moment from alien predators and fanatics is that some other advanced civilization rose up to counter them before they arrived anywhere near Earth, like the Green Lantern Corps. Another saving grace is our distance. We are kind of out in the boondocks when it comes to galactic location. Is it worth the trouble traveling all the way out here? See the running theme so far?

Sure we complain about how hard it is to travel to the stars but that could be buying us time for when we do have first contact. Perhaps by the time a malevolent race discovers us and sees that we won’t be an easy conquest, they’ll move on. Keep our fingers crossed.

J.L. Soto