Our mission is to reach immortality. Death is our ultimate enemy. We all face it eventually, but we continuously challenge it, and we a...
Our mission is to reach immortality. Death is our ultimate enemy. We all face it eventually, but we continuously challenge it, and we are trying to delay it until we find a way to cease death from our lives. Our self-consciousness makes us suffer from the ultimate end, from our death. We are conscious of it, and this is why we suffer from the passing.
Why is this ultimate end? Is it unavoidable? We know, our body is like a complex biochemical factory, machinery. Incredibly complex, still a mechanism and we know everything that is made from matter even if it can go wrong, it can be fixed when we have the necessary knowledge, energy, and matter. Our car can run forever if we continuously replace the failed parts. Is it still the same car? Yes, because its structure is the car, not the given matter. Our system looks the same. If we could replace all our failing parts, we could live forever. Could we? Our body is practically doing this replacement constantly. Not our whole body parts, but still all the matter of our body replaced periodically, yet our structure remains the same. If this mechanism is working, why we die?
One kind of answer is religious. God created us and made us mortal because we are a sinner and we need to dignify ourselves to reach immortality. This kind of reasoning and explanation yet looks fishy. It is possible, but it is unlikely. If we look around, all multi-cellular living creature destined to die, not just we, the human. It is hard to apply the same religious reasoning to all living creatures. It must be something more fundamental to exist behind the death, and that reason must be valid on us too, knowing, we are relatives of the other species.
However, immortality is not an unknown, impossible feature in life on the Earth. Single-cell organisms do not die on their own. They can be eaten, they can be destroyed, they may be starved to death, but decease has no meaning to them. They are splitting in the creation of a new life and have no reason to say which was the original, the old was, and which one is new. Both are both. In this sense, single-cell organisms are immortal, can live forever until an external circumstance or an inside malfunction kills the given cell. Single-cell organisms have no internal mechanism to the destined death. Multi-cellular organisms have. Why? The answer is not trivial, primarily because multi-cell organisms are built-up from single-cell organisms. Why is this pre-programmed, inevitable death of the multi-cellular organisms? Would not be more beneficiary from the viewpoints of the species to let to live the individuals indefinitely, have offspring and make nature, the external circumstances limit the population? Why is preprogrammed death?
We are getting to know the mechanism of natural death on the level of the cell. There are at least two significant factors. One of them is that every cell division creates mistakes in the DNA in the copy process. As more and more divisions occur, these mistakes are accumulating, and ultimately reach the limit where the complex operation of the cell becomes impossible, and the cell dies. The replication of the DNA has an error-correcting function, but even with this correction, the replication is not perfect. It could be better, but ultimately it has a "built-in" error level, and thus determines the lifespan of the cell.
The second method is the telomere degradation. Telomeres are parts of the genes. Their function is to protect the genes from the damaging effects. As the cells divide, the telomeres become shorter and shorter. When they become too short, the protecting role will not function any longer, the genes become vulnerable and ultimately become dysfunctional, and the cell dies. The telomere shortening must be a built-in property by the evolution too, and its speed must be determined on the species level giving a particular limit of the average lifespan.
However, these are only the processes of how we die but not the answer, why. There are two theories about how these processes developed. One theory explains it by genetic mutations, which affect the multi-cellular life at the later stages. This kind of mutations can spread in the population easily because it will not take effect on the early, reproduction phase. If these mutations cause the cells and ultimately the individual to die, these mutations can be dominant in the population. The telomere shortening can fall into this category. It will not affect the life of the cell until becomes the telomere too short.
This theory can explain the general presence of these kinds of mutations, but cannot explain its stability. A mutation must be beneficial to maintain its presence. Otherwise, the goal-less evolution would select it out with a high chance. However, we see mortality is a universal feature of the multi-cellular organisms. Cannot see the telomere shortening has an evolutionary benefit of its own for the species to remain constantly present and avoid de-selection. Telomere shortening looks like for the preprogrammed death only. It can spread in the population but difficult to explain its universal presence because it has no other beneficiary function. What is the evolutionary benefit to die then?
The other theory explains the preprogrammed death by a kind of mutation, which creates beneficiary functions in the early stages, but at the later stage, it causes the death of the cell. This kind of mutation can spread in the population too and can become dominant as well. The erroneous DNA replication seems to fall into this theory. The random changes could create a benefit to the cell by discovering new methods by these changes, but a highly specialized, multi-cellular organism most likely could not benefit from these random changes. Therefore, this process instead falls better to the first kind of theory discussed before.
Currently, we do not know any genetic function, which creates benefit in the early stages, and the same function cause death at the later stage. Even if we would find such a function, why the evolution does not lead to a mutation, which carries no death only the benefits in the long run, if the death function has no evolutionary benefit?
If we want to understand and try to explain the generally present death, we need to find its evolutionary benefit. It must have. The answer may be in the difference between the life of the single-cell and multi-cell life.
Single-cell life, even if it is living in a colony has a high level of independence. It can mutate without risk the bigger, containing system, the strain. It is not so in multi-cellular life. The multi-cellular organism has cells with particular functions. These specialized cells cannot mutate freely and lose its specification by the changes without risking the coordination of the whole system. The specialized cells in the multi-cellular organisms cannot change as freely as in the single-cell organisms. However, there is a controversy. Every replication, whole or part, can create mistakes in the copy process. These mistakes are necessary to let flexibility, to let the evolution, its adaptation function to work. Otherwise, the evolution could not fulfill its function, to adapt the system to the changing environment. However, because the system built up by specialized cells, the mutations eventually will lead to a non-coordinating cell, which would cause the whole system dysfunction. It could lead to a disintegrating system, to the death by itself. However, until it happens, the organisms still replicate itself in these, highly mutant forms. These mutations can be beneficial until a limit, but letting the species poisoned by a high level of mutation would risk the species. There must be a balance. If the limit of the chance of the beneficiary mutations reached, it is better to let the whole, multi-cellular organism stop reproduction. Because an organism's goal is to reproduce itself, it is more beneficial to the species to let to die its non-reproductive members.
Maybe it is why preprogrammed death exists in general. The random mutations and the shortening telomeres are working together to create sustainable species. The death is not for freeing the place to the next generation. It is to prevent harmful mutations to poison the species. If we make our lives longer, we can see the harmful effects of reproduction by the more and more likely chance of cancer.
Death has an evolutionary benefit for multi-cellular organisms. Death is our destiny. Death is rooted in evolution. Also, this is the way how to avoid it. The multi-cellular organisms which create species under the law of the evolution are destined to die because better to die than live with harmful mutations. However, if we would release our species from the law of evolution, we could avoid death. We are working on it in different ways, and if our species exist long enough, we will find the way. We are destined to die, but our future is to live forever. If we smart enough, and if we can free ourselves from the evolutionary ancestry, hostility, greediness, and build a cooperating society, we may fulfill our destined future.
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