In a constantly changing world, there are few things we can count on.  There is one thing that never changes, however, and that is the fact that our bodies are always changing.  In fact, from the moment we’re conceived, we are in a constant state of transition, right down to the very building block of life, our cells.  You’re a zygote, then an embryo, then a newborn, then a toddler, then a holy terror your parents wish was never born, and ultimately, an adolescent, when the real fun begins.