Discussion of all aspects of cellular structure, physiology and communication.
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Hi everyone, so this entry is just about something that occurred to me recently that I couldn't find much information on, and I decided to try and focus my thoughts on it and write it out as clearly as I could. The following represents my understanding of the subject, so feel free to call me on any mistakes or incorrect assumptions I may have made, or if you feel I didn't explain something in the piece coherently enough. Any thoughts on the matter are greatly appreciated.
The overwhelming majority of all cells in the human body have a fixed lifespan. As they deteriorate and accumulate damage over time, they will inevitably reach a point where they are too damaged or senescent to continue functioning efficiently and correctly. When this happens, the cell is metabolised and replaced by a new cell. The central argument that I will develop focuses around the fact that this cycle of cellular life is perpetuated numerous times throughout the course of a human life-time for every cell, propagating at different rates for different cell varieties. It will be shown that these processes of replication and replacement raise questions regarding what makes us “us”.
From the moment of conception we are continuously growing and changing. Pushing on from the humble beginnings of a single embryonic cell, mitosis is the mechanism by which we have gradually increased in size, a process which is propelled forward and manipulated in minute detail by our genes. Our cells are continually engaged in a cycle that comes full circle at the point where the cell dies and has its responsibilities taken over by a replacement cell. This cycle is fueled by inputs – food, water and oxygen. Stated more simply, the useful matter from the food you eat replaces the matter you lose through damaged or dead cells.
Here I come to the first major point of this post. The nature of this cycle infers that you are currently composed of completely different matter from that which you were composed of at a much earlier moment in your life. Old matter leaves your body, and new matter comes in to replace it. The implications of this are that you are literally a different person than who you used to be. Not different in appearance or behaviour, but different in the sense that you are no longer made of the same material. In other words, you are a clone of your younger self.
But what does that say for us? It “feels” like we have consciously existed in these bodies for our entire lives, but even consciousness has a physical basis in our bodies – it arises from the particular structure of the neurons in our brain, and can be physically altered or destroyed by doing damage to our brain. All cells must be renewed and replenished on an ongoing basis, and what does this maintenance process require? New matter, obtained from inputs like food and water. There seems to be no way of avoiding the resulting conclusion that my current “self” (referring to the current body of matter I am composed of), did not exist at an earlier time in my life, and therefore was not actually present for the memories I have from this earlier time. This leads me to two very different possible explanations:
1. I am being “replaced” by new matter on an ongoing basis, but because the memories of this body are retained along with the blueprint for my body (my DNA), I can never be consciously aware of any transition. It “feels” like I have always been in this body, and have existed as me since the moment of my body’s conception, but in truth I am being deceived by my own memories into believing that I was present in this body when the events from those memories took place.
2. My sense of “self” has an extra-corporeal basis, and has always existed in this body.
The difference between these explanations is that the first one may eventually be physically testable, whereas the second one is physically independent, cannot be tested, and can therefore therefore have no basis in testable evidence. The only way I can work out which answer is correct is by answering the question: what makes us “us”? Are we the body of matter that we are composed of, or are we the information “blueprint” from which our bodies are built? Are we a little of both?
Let me employ the analogy that DNA is a construction blueprint and my body is a machine that is built to the specifications contained in this blueprint. The completed blueprint is made up of a collection of sub-plans that all focus on the manufacture of a different individual piece of the machine. These sub-plans are genes. Over the generations, genes are repeatedly replicated, reshuffled, carried on and used in different combinations to make new blueprints that impose their construction plans on new matter and build new bodies.
But these “blueprints” are also being replicated and replaced on an ongoing basis, so the original physical copy of DNA that started off the production of your body no longer exists, having being replaced by copies of that same blueprint. The original matter that you were composed of is now gone, and only the information contained in your blueprint remains constant. Due to aging and death, even the final copy of this blueprint is eventually destroyed. But this blueprint manages to manipulate many different bodies of matter before it is destroyed, so it can be said to outlive countless reincarnations of your body as it progresses through each “clone” over its lifetime. This brings me to the next major point I want to make – that a “lifespan” isn’t the length of time that our bodies exist for, but can actually be more accurately defined as the length of time that our particular sequence of genetic information exists for.
So the resulting question is: what makes me “me” as opposed to somebody else? Have I really existed in this body for my entire life or are my memories fooling me into believing so? Logic would appear to dictate that I am in fact continually being replaced without ever being consciously aware of the process. What makes me “me” at any instantaneous moment can only be defined as my exact composition at that particular moment, and at any other moment, “I” do not exist. Therefore, “I” have instantaneous physical form, and for all other moments in the life cycle of this body, “I” am not present.
In conclusion, I propose that our bodies should not be considered to be fixed individuals in the true sense, and that we can be more correctly described as part of a cumulative, ongoing process of genetic information transfer – a process in which our present state at any one moment is only a fleeting step.
In particular, I wanted to know is it an accurate statement to make that eventually after some period of time, all of the original molecules used to make up your body have gradually become replaced by other molecules of the same type?
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