In our own twentieth century, mankind learned to produce energetic radiation in concentrations far surpassing those we usually encounter in nature. Again, a new technology is resulting and again there is the possibility of death.
The balance in this second instance is less certainly in favor of the good over the evil. To shift the balance clearly in favor of the good, it is necessary for mankind to learn as much as possible about the new dangers in order that we might minimize them and most effectively guard against them.
To see the nature of the danger, let us begin by considering living tissue itself—the living tissue that must withstand the radiation and that can be damaged by it.
Cells and Chromosomes
The average human adult consists of about 50 trillion cells—50 trillion microscopic, more or less self-contained, blobs of life. He begins life, however, as a single cell, the fertilized ovum.
After the fertilized ovum is formed, it divides and becomes two cells. Each daughter cell divides to produce a total of four cells, and each of those divides and so on.
There is a high degree of order and direction to those divisions. When a human fertilized ovum completes its divisions an adult human being is the inevitable result. The fertilized ovum of a giraffe will produce a giraffe, that of a fruit fly will produce a fruit fly, and so on. There are no mistakes, so it is quite clear that the fertilized ovum must carry “instructions” that guide its development in the appropriate direction.
These “instructions” are contained in the cell’s chromosomes, tiny structures that appear most clearly (like stubby bits of tangled spaghetti) when the cell is in the actual process of division. Each species has some characteristic number of chromosomes in its cells, and these chromosomes can be considered in pairs. Human cells, for instance, contain 23 pairs of chromosomes—46 in all.
When a cell is undergoing division (mitosis), the number of chromosomes is temporarily doubled, as each chromosome brings about the formation of a replica of itself. (This process is called replication.) As the cell divides, the chromosomes are evenly shared by the new cells in such a way that if a particular chromosome goes into one daughter cell, its replica goes into the other. In the end, each cell has a complete set of pairs of chromosomes; and the set in each cell is identical with the set in the original cell before division.
