In basic physics, maybe in sixth grade or so, you're told that every action has an equal and opposite reaction: this is known as Newton's Third Law of Motion. I believe that this extends farther than physics, that this is applicable to all areas of life. To start this off, I just want to point out a couple of obvious ones: when you inhale you have to exhale, when you consume nutrients you expel waste, when you drink you have to urinate, night and day.
If in fact everything has an equal and opposite reaction to every action that means that there must be something triggering each action and reaction to occur. Thus, these things are connected through some force. Let's take a look at Newton's First Law of Motion: A body at rest will remain at rest, and a body in motion will remain in motion unless it is acted upon by an external force. What happens when a body at rest is acted on by an external force? Well, logically it would either be in motion or continue to stay at rest. But what exactly starts each action?
In order to move, energy is needed. This is why humans eat, and why they fill up their cars with gasoline or electricity (or whatever powers your automobile). This is not a ground-breaking phenomenon; people have consumed food since the dawn of their existence in order to live and hopefully reproduce by giving life to the next generation. This happens with animals, plants, and other organisms, however, the process of obtaining energy and reproducing varies.
So now we know that having energy (and parents) causes things to be set in motion. What came before our parents? Well, their parents and so on and so forth back to the split in the road: Adam and Eve or evolution from a different species. You can believe either one or none of the above, doesn't matter to me. What I'm interested in is the before. So what happened before humans and the growth of the most destructive civilization planet earth has ever known? The most commonly held belief is dinosaurs and their era of dominance. Before them? More animals roamed the earth and flourished in the oceans. Similar to how humans started at one point, plants and animals, not being immortal primordial beings, had to have some definite origin. So let's go back even further.
Most people are familiar with the notion of The Big Bang. All the substance in the universe at one point was contained in one small space then rapidly expanded, like an explosion. But did it just sit there until the arbitrary moment when it felt like popping? Or did God manifest it? I don't know. I'm just a twenty year-old college kid who likes to write, read, and have a good time.
"That you are here—that life exists and identity,
That the powerful play goes on, and you may contribute a verse."
-Walt Whitman from "O Me! O Life!"