Alien Seed Theory
There has been a theory floating around that states that advanced alien life forms may have
'seeded' our planet with the fundamental building blocks of life (carbon molecules, hydrogen, etc.) in order to kick-start the
proliferation of life on Earth. One can only offer speculation to this theory because we really don't know how exactly
life came about on Earth. Some believe an asteroid carrying primitive forms of microbial life impacted on Earth and began life...others believe
the Earth itself already possessed the necessary fundamentals in order to create life during the formation of the planet. If aliens did seed Earth, then
they weren't planning on sticking around for 4 billion years to see the advent of the Human technological age.
Evolution is a complex thing...and a multitude of factors come into play that direct the path of life. One cannot simply
just seed a planet with the building blocks of life and hope to create beings of high intelligence like Humans within the first 4 billion or so years...
natural factors could inhibit the propagation of such life or halt it altogether for the entire life span of the planet.
The Mass Extinction Event caused by aliens?
If that gigantic asteroid had not of hit the gulf of Mexico and ejected so much material into the atmosphere that it blocked out all
the sunlight and subsequently killed all the plant life and wiped out the dinosaurs, Homo Sapiens would likely not of been born. So, it is no surprise
that some would wonder if aliens had anything to do with it. Even our technology is capable enough to manipulate the path of gigantic asteroids, so why
would it seem so far-fetched? Well...it is more likely that an asteroid -- missing Jupiter and Saturn -- strayed from the asteroid belt (between Mars and Saturn) and impacted
on Earth. Perhaps this is nature's own fail-safe...if you're too dumb to protect yourself, make way for other, more complex forms of life.