I.7 Living systems develop useful properties through the action of natural selection
Biological evolution involves a number of processes, through whose effects organisms gradually develop over time, mutually diverge and accumulate changes in their structure and in their behaviour. At the present time, the most important are considered to be natural selection, mutagenesis, genetic drift and molecular drive. The separate chapters will be devoted to the individual mechanisms; however, it should be stated here that natural selection plays an absolutely essential role in the evolution of living systems. It is through its action that useful (adaptive) traits are formed.
Natural selection is capable of systematically selecting, from randomly emerging hereditary changes in traits (mutations), those rare changes that are, in their manifestations, beneficial, advantageous and useful from the standpoint of the lives of their bearers. The probability of the formation of useful mutations is certainly very small; most newly formed mutations are neutral ordetrimental from this point of view. However, if, during evolution, a process (natural selection) is active that systematically tests all mutations and selects those that improve the functioning of the organism and eliminates the rest, it is apparent that all contemporary organisms must exhibit a high level of usefulness.