Biology is its own science. I do not blame outsiders who have little or no knowledge of the subject, to jump to conclusions based on the wrong premise. To the untrained human eye, all human cells look the same. They have a cell membrane and several organelles and a nucleus with a singular DNA which is carefully replicated in every cell of the human body. Any change in the sequence of chemical bases by mutation or the activation of segments of normally dormant, unread DNA can have disastrous consequences on the whole body. This is what cancer ultimately is! Because people see that all the body's cells have the same DNA, it is easy to conclude that all the body's cells have the same potential to grow and develop. A skin cell has the same potential to develop as a kidney cell, and a kidney cell has the same potential to develop as a liver cell and similarly this has the same potential to develop as an embryonic cell, right? After all, what we see are a bunch of human cells from the same body with the same DNA all with their own active potency to develop. However this information is incomplete. Besides the Mendelian aspect of genetics, now a Lamarckian one has now been discovered and not realising and understanding this important categorisation is like saying that the President of Malta has the same political function and powers as the President of France or that of the USA. There is a profound constitutional difference in both biological and political examples!
Epigenetics is a relatively new aspect of genetics. The human DNA molecule is such a biologically massive molecule that it cannot stand intact on its own. In layman's terms it needs its own scaffolding to prop it up. This scaffolding is found in a number of different Histone protein molecules and others which surround it. Imagine a tall building where one works that is surrounded by a scaffolding of key clamps on which lie a number of planks and other working tools and platforms, to say nothing of the workmen. One can get the best view from the building but if a scaffolding platform is in front of one's view, one can see nothing or very little. Likewise, these Histone molecules can determine what is read in segments of the DNA and what is not. They can switch on and off parts of the DNA code.
To make matters more complex, the workmen on the scaffolding may decide to black out certain windows in the building as they work, making it impossible to see anything. This happens in the DNA too, as certain segments are blackened out and cannot be read by a process called methylation, where different chemical radicals or groups are newly attached to the DNA, in effect blotting out that particular section from ever being read. This is what distinguishes different body cells from each other. Kidney cells have their own methylation patterns, which is why they behave solely as kidney cells and which distinguishes them from liver cells or skin cells. Although they have the same DNA, they behave differently because they have different methylation patterns! Stem cells are cells with relatively very few methylation patterns so they can be artificially methylated and induced to produce any body cell we want them to by causing the appropriate methylation patterns in them with the addition of certain chemicals. However, they are already partly methylated so the changes we can produce are limited. We call these cells pluripotent stem cells. We can induce pluripotent stem cells to form skin, liver, kidney or any other cell type we wish, including nerve cells. What about the early embryo from the day one zygote to the eight-cell stage morula? These cells are very, very special, unlike any other cells in the human body. They are completely clear of any methylation patterns, and as tabula rasa they are able to be completely methylated anew as the body requires, whereas the potential of all other specifically methylated cells is only to develop into particular cells types such as skin, liver or kidney, these particular cells have a potential to develop to a total end. They are totipotent; they have the active self-fulfilling potency to develop into human beings. Whereas other cells develop into human body cells, these cells intrinsically develop into a human being! Their methylation patterns progress under the influence of the external environment so that different environments can affect methylation patterns differently. That is why identical twins have the same DNA but the methylation patterns are different according to the different environments which affect them separately! Those who are well-acquainted with identical twins can tell the differences between them and these can be picked up epigenetically.
After the eight-cell stage, human embryonic cells become pluripotent as single cells but still have, as a whole bunch of cells, a human active potency. The word active here is used to signify a self-moving capacity. Some will unwisely argue that now that different pluripotent cells of the so called 16-cell stage blastocyst are not all destined to become the foetus but some only the placenta. Yes, but these are part of the whole and if separated will cause death of the whole. My liver cells do not have the importance, morally, that I have as a human being, but removing my liver will in effect mean that I will die very quickly! You would be charged with murder had you to do so!
Human reason based on the objective philosophies of Socrates, Plato and Aristotle will show me that I should behave towards others as I want them to behave towards me. The so-called golden rule in ethics means that I should respect the life of other human beings as I would want them to respect mine. These human beings should include those at all stages of development including the human totipotent cell with full human active capacity and the whole developing embryo and foetus. When we study human anatomy we spend a long time studying embryology because we are aware that human active potency starts from the already independent one-cell zygote stage with a fully independent newly-completed singular DNA at a stage of complete epigenetic non-methylation. Some people of course do look at the anatomy without taking into consideration the consequences of philosophy. They have in effect lost their reason.
Society now complicates issues with the presence of several consequentialist, utilitarian or existentialist subjective ethics, which ultimately pits the assets of one human being against that of another rather than respect human beings as being all of the same worth. In effect to these subjectivists persons, some human beings are more important than others especially those who are actually born or can actually think or can actually walk or can actually vote, which for some is what human dignity seems to be all about. Rather than looking at the humanity of the individual they look only at the subjective worth! I want no part of this. Where science has shown the objective truth, reason and natural law should follow. Failure to do so will ultimately only bring humanity and oneself to ruin. Worse of all, it will dehumanise one to the point where the singular image of humanity is no longer visible. Some human beings tend to behave as if there is no objective truth in the world. They constantly sway from one subjective truth to another as it suits them. It will be quite a shock for them to find out that there is objectivity in our ethical decisions. It reminds me of the real story of St Theresa of Avila. The devil used to tempt her by telling her that it would be a pity that after all the sacrifices she was going through for the sake of an objective truth, she had to find out that there was no life after death. She craftily used to answer that it would serve her even less, if after having listened to him and behaved irresponsibly, she would then find out that there was a life after death after all! But then again, subjectively, Theresa may never have existed!
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