Our body is an incredibly complex symbiosis of multiple systems To those demonstrated in the video, we can add a dozen more. But not only are these systems in sync with each other, they also react together to changes in the world around them. Of course, we take this for granted. But it's hard to stop marveling at the uniqueness of our bodies🙌🏻. Even the seasons have a certain set-up: spring and summer are a period of growth and reproduction, fall and winter are a period of regression and limitation.