Humans might be the aliens in the universe: The funny life cycle

I was watching the discovery channel tonight and heard some scientist say that the source of life is not earth. We are just able to survive because of the strategic positioning of the earth. That’s why it can hold water on its surface in liquid form and blah blah blah. What caught my attention though was when she said that humans, who are willing to go the distance to find signs of life in space, might actually be the aliens. How so? If earth wasn’t the source of life, then what was? Food for thought.

It makes me wonder though, if there are other life forms out there somewhere, maybe civilizations, do they exists as humans do? Do they try to live the same way we do? Do they go through ‘life’ as we know it?