THey are some of the only 2 constants that we know of. Even after clouds, and moon cycles they return over and over.
Many people associate it with day and night, duality ( which to me is just 2 levels of explaining the same thing). Im slightly weary with it, because it can lead to 2 sided arguments IMO, unless you under stand, that day doesnt turn directly into night. There is evening, and the dawn, and trasitions.
I bet its jsut subconscious. Which doesnt mean its fake, or wrong. Its interesting to think of our interests. I have no idea why im drawn to ancient things, and growing things, and life and evolution, I just roll with it. You see some pretty cool things down the road never taken