The lives of all organisms are restricted. After a more or less prolonged phase of ageing, every living thing dies. We all accept this inevitable fate as ‘biologically’normal, but this fatalistic attitude stems largely from our experience with artificial objects. These are subject to natural wear and tear during their use, eventually break and become unusable—’dead’in the biological sense. But the wear and tear and loss of function of technical objects and the ageing and death of a living organism are fundamentally different processes. Artificial objects are ‘static’closed systems. They usually consist of the same basic material that becomes ‘older’over time. Their ‘ageing’follows the laws of thermodynamics. And even if we can replace defective parts, such as in a broken car, the object as a whole is slowly worn out until it breaks. Although the same law holds true for a living organism, ageing and death are not inexorable in the same way. An organism is an open, dynamic system through which material continuously flows. The destruction of old and formation of new material are in a permanent dynamic equilibrium. Within about seven years, a human replaces roughly 90% of the material of which he or she is built. This continuous exchange of substance is comparable with a spring, which more or less maintains its form and function, but in which the water molecules are always different.

Ageing and death should therefore not be seen as inevitable, particularly as biological systems have many mechanisms to repair damage and replace defective cells. In principle, it is not necessary that a living organism should age and die as long as it retains the ability to repair and renew. Nevertheless, ageing followed by death is a basic characteristic of life, as nature regularly needs to replace existing organisms with new ones. Because of variations in their genetic material due to mutations or recombination, these new individuals have different characteristics, which in the course of their lives are tested for improved adaptation to existing environmental conditions. Immortality would disturb this system of mutation and adaptation as it depends on the availability of room for new and improved life forms. Thus, death is the basic precondition for the frictionless and rapid development of new species that can successfully adapt to changing environmental conditions. This is an evolutionary principle.