Your body is made up of tiny living units called cells—some 100 trillion of them, according to one estimate. Inside each cell, within its nucleus, there are thousands of genes. They are individual units of heredity that control the cell and therefore determine some of your characteristics. Many genes may order your blood type; others, your hair texture, your eye color, and so on. So each cell carries a miniature blueprint or codebook made up of genes, which contains all the instructions needed to build, repair, and run your body. (See diagram, page 5.) Could all of this have happened by accident?

Scientists have thus found the cell to be amazingly intricate. In his book The Fifth Miracle, physicist Paul Davies states: “Each cell is packed with tiny structures that might have come straight from an engineer’s manual. Minuscule tweezers, scissors, pumps, motors, levers, valves, pipes, chains, and even vehicles abound. But of course the cell is more than just a bag of gadgets. The various components fit together to form a smoothly functioning whole, like an elaborate factory production line.”