The life of a human being cannot be totally described or defined by the detailed analysis of all the activities that are necessary for life. It is rather the sum of these activities co-ordinated in a delicate and beautiful way to form a unitary phenomenon which we call human life. Since the organisation of the human body is so complex, it is easily damaged, although damage can sometimes be repaired. The testing of nuclear weapons causes damage to life which cannot be repaired, and which poses special moral problems because future generations are also affected.
The final executor of the coordination of the human body is the nervous system, organising all the physical activities of the different parts of the body, organising many chemical activities, such as the secretion of chemicals from the glands, and finally creating and organising the intellectual and emotional activities of the brain.
And yet the nervous system is itself coordinating a series of already delicately organised systems. Each organ in the body, be it the liver, a muscle, or the intestine, is itself a finely balanced system of many millions of cells acting in concert to produce the unitary function and nature of the organ itself.
Finally, at the deepest level of analysis, each cell is a unit produced by the coordination of reactions between the complex ‘organic’ chemicals which alone are capable of reacting in such delicate and organised systems. The total activity of every cell in the body is controlled, organised and balanced by the contents of a single tiny body present in each cell. This tiny body is called the nucleus. Since the cell is the smallest dynamically organised unit in the total organisation of the body, the organisation of the cell is the most fundamental activity in the life process.
The adult human body is produced only after a long period of development, taking about 20 years. From birth onwards development is comparatively slow, but the new born baby develops in only nine months from a single cell, the fertilised egg, formed by the fusion of sperm and ovum. The responsibility of initiating the marvellously complex processes which lead to the formation of the adult human being rests entirely on this single cell. Furthermore, the total potential for the whole developmental process is present in the fertilised egg. The pattern development will take, and its consequences, the final form and nature of the adult produced, are decided
As development proceeds, the fertilised egg divides into two cells, which in turn divide into two themselves, and so on, eventually giving the total number of cells in the human body. This number is unaccountably huge, yet each one of these cells contains 46 chromosomes in its nucleus, and the same genes as the fertilised egg. This extraordinary feat is achieved by the longitudinal division of every chromosome in a cell as it divides. One half of each chromosome goes into each daughter cell, and then builds up the lost half. Since the genes are carried on the chromosomes, they also divide in half, and each, by reconstituting the lost half, reconstitutes the lost half of the chromosome. Since this division occurs in every cell from the fertilised egg onwards, each cell in the adult body has the same genes present in it as the fertilised egg. Every cell in the adult body thus has 46 chromosomes in its nucleus, until sperms or ova containing 23 chromosomes are formed in the testes or ovaries, for the procreation of the next generation.
The complexity of the processes by which one generation arises from the next, through fertilisation and embryonic development, indicate the massive degree of organisation in the human body. And yet the adult human body, just on account of this complexity, is subject to damage which can bring the whole organisation toppling into the ruins of death.