Apoptosis

Carl Sagan said each of us is an integrated entity of 10,000 trillion cells. Each cell carries a complete copy of the blue print of you, according to which you have been created and sustained. Somehow each cell knows its own job: remember to transfer electric signal if it's a part of your nerve system or never forget secretion if it's in your islet of Langerhans... Never in your life you have to remind a cell to keep an eye on the insulin level after each meal. It will do that for you. When you eat, it's your cells that extract nutrients through amazingly complicated sequential process. They intake oxygen from the air to produce energy, distribute it to every nook and cranny in your body parts. They carry off your wastes. Every process it takes is to keep you you...
It reproduces by itself. That's what keeps you going. It dies when it is no longer necessary, through the process called apoptosis by eating up itself in a manner you can call suicide. The death is also a vital process that keeps you alive.
Come to think, all the above behaviors - plus an uncountable number of others - are all just random action and reaction, a sequence of endless encounters directed nothing more than elemental rules of physics. There is clearly no thinking behind any of the actions of the cells. It all just happens smoothly, repeatedly and so reliably that seldom are we even conscious of it, let alone appreciate it. Yet somehow all this produces not just order within the cells but the perfect harmony right across you. How miraculous it is that trillions upon trillions of chemical reactions add up to cell behaviors and then 10000 trillions of cell reactions add up to a eating, defecating, feeling, worrying, contemplating, decision-making you.
There must be a coordinator behind all that? I have no idea. I just bow my head to the greatness of life, only an infinitesimal part of which I am able to occupy against impossible odds, with an incredible luck, as a powerless and powerful, trivial and important existence. And, sure, apoptosis of individuals including me is an inevitable, necessary process for life. Old replaced by young. Thank God.