Now we cross the line from the molecular to the living. Whether bacteria, animals, plants or people, we all have cells. Cells consist of many biological elements that are enclosed in a cell membrane that allows certain molecules to pass out of it and let others in.
Cells are tremendously complex and more complicated than any machine man has ever built.
Even the smallest bacterial cell has 100 proteins, DNA, RNA, and contains one hundred billion atoms. The simplest cells are not more primitive than, or ancestral of, larger ones. This poses an immediate problem. It either all works or nothing works. This is challenged by the knowledge that even small errors cause devastating biological consequences.