Mortality, Evolution, and the Temporary Individual
Key Idea:
The survival of the species appears evolutionarily more important than the unlimited survival of the individual.
After asking what a human being actually is, we are inevitably confronted with a characteristic that defines the entire human condition: mortality.
Why are human beings mortal? And why does nature appear to be organized in such a way that living organisms eventually age and die?
An important part of this process takes place on the cellular level. Throughout life, cells are continuously damaged by internal and external influences. The body attempts to repair this damage by replacing old cells with new ones.
During every cell division, genetic material is copied. However, this copying process is never completely perfect. Small errors, damage, and functional losses gradually accumulate. After enormous numbers of cell divisions, the organism as a whole begins to function less efficiently. The body gradually “wears out.”
More information about the aging process is provided in Appendix 4.2 (The Aging Process in Humans)
Yet this raises an intriguing question.
When a woman gives birth to a child, a new organism emerges that, despite the age of the parents, is once again capable of potentially living a complete life. This seems to suggest that mechanisms exist which are capable of producing relatively “fresh” genetic material.
Why, then, does the body not simply use these mechanisms to continuously renew itself completely?
Perhaps the answer lies in the way evolution functions.
Humanity still exists today because the species has continuously adapted to changing circumstances. This adaptation generally does not occur because a single individual fundamentally transforms itself, but because over many generations new variations continuously arise within the DNA of the population.
When human beings live for long periods in regions with limited sunlight, lighter skin may become evolutionarily advantageous because it allows vitamin D to be produced more efficiently. In regions with intense sunlight, darker skin may provide protection against harmful ultraviolet radiation. In similar ways, countless other traits have emerged or changed throughout evolution.
These changes arise because every new generation consists of new combinations of genetic material. Some of these combinations prove better adapted to prevailing conditions than others. Individuals with relatively advantageous traits generally have a greater chance of reproducing, causing those traits to be passed on more frequently to future generations.
From this perspective, evolution appears less focused on preserving the individual organism and more focused on the survival of the species through continuous variation, selection, and renewal.
Human life, from an evolutionary perspective, is therefore temporary. The species continues to exist because older generations are gradually replaced by new individuals possessing slightly different genetic combinations. Evolution thus operates not primarily through the permanent adaptation of a single individual, but through continuous replacement and selection across successive generations.
Perhaps this is evolutionarily more efficient than maintaining existing individuals indefinitely. Older organisms may become less flexible in behavior, physical adaptation, or reproduction, while new generations introduce new genetic possibilities that may better correspond to changing environmental conditions.
From this perspective, the human being appears not so much as the final goal of the system, but rather as a temporary vehicle for transmitting and renewing genetic information.
In nature, there are also organisms that appear to follow a different evolutionary strategy. Certain species of flatworms, for example (see Appendix 4.3 The Aging Process in Flatworms) possess strong regenerative abilities and thereby approach a form of functional immortality.
Human beings do not possess such capabilities on a comparable scale.
This need not be viewed as a deficiency, but may instead relate to an evolutionary system in which continuous genetic renewal proves more important than prolonged individual preservation.
The question therefore may no longer be why human beings die, but why the evolutionary system itself appears dependent upon mortality.
Perhaps mortality is not a flaw within the system, but rather a necessary condition for continuous adaptation, variation, and evolution.
And with that, we once again arrive at a fundamental tension that affects not only biological processes, but ultimately human societies and moral systems as well: the tension between the individual and the whole, between stability and change, between preservation and renewal.