A multicelled creature is like a network of computers. It requires parallel computer architecture on a huge scale to operate multicelled creatures such as mammals with billions or trillions of cells, all working in harmony, each doing its task. The nervous system and the hormonal system are two important networking systems used by mammals. Changing the way a computer works requires new programs. Other times, reprogramming a computer is more trouble.
Biological evolution happens when cells are reprogrammed.
Somehow, new genetic programs are installed and activated. These are some of the questions that Cosmic Ancestry attempts to answer. There are two kinds of cells. You might guess the two are plant and animal cells. This distinction, however, is even more profound.