No less interesting question is the interaction of cells, as a single organism. On the example of a flock, one can see how the fry flock one way or how the ants are busy in one thing. So the cells of one organism work in unison. And they provide a constant and strong connection into one and the same shape. How is this possible. Why do not they grow up, whatever. But not only from here to here. Reminds the operation of the 3D printer. Who builds the future product step by step. Builds on the given drawings, and therefore has an algorithm of actions. If we assume that in each cell such an algorithm is already laid, then the process of building the organism during growth is clear. It is enough for her to feed nutrients and at some point she will turn on and begin to perform her actions on the alarm clock. If she does everything right, then there should not be any problems. But here something was mishandled and there was a failure in the program or, external factors start not those actions. A tumor, cells are copied, eat and all. Parasitize on the whole body, than it undermines its capabilities. Gradually poisoning it and killing. Everything happens this way, because the cell does not see the big picture. And no one manages it. She just does her job day by day, like a clock. And no one can get into her brain. Rather, of course it is possible to climb and most likely it will be, only what it will lead to.

By Boumphreyfr - Own work, CC BY-SA 3.0, Link