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The human embryo begins its story at the formation of the zygote at fertilisation. This is a single cell structure that grows and grows and grows until it becomes a whole organism. This occurs at birth. The human embryo is peculiar because there are debates as to what its nature is. Is the human embryo human or  is it subhuman? If it is human the killing of the human embryo then become murder. If it is not human then what is it? At what stage does it become human? There are several theories and the theories are as follows. We have the conception theory which is the absolutist theory and this is the most widely accepted. It is strange though that it is the latest model of understanding of the human embryo having only been used in the19th century because of the discovery of the human egg by von Baer.  Before this several models were followed including the ones used by the Jews and the Roman Catholic Church which states that the embryo become only human only when it reaches the fetal stage at which time it would have acquired its appendages  so that it is recognisable as human, that is, it will have  a head; it will have limbs. But before then, it was not considered  human. This is because the human egg was not recognised as an entity involved in fertilisation until the discovery by von Baer in the 19th century. The advantage of the theory of conception is that it has science behind it. Since the very first process of life begins at fertilisation which is the same point of conception and there is no other process, which separates new life from maternal life except this one. It is therefore difficult to expect scientists to believe that life begins before this.

Strangely though it is even the scientist themselves, by that I mean investigative scientists who refuse to accept the theory of conception. Most other people who may be shack scientists or who may have little knowledge of biology support this theory enthusiatically.

 

The next theory is the Morula theory. This theory has the least of support. It is found mostly amongst modern reproductive biotechnologists  who have discovered that maternal transcription of DNA which controls the early embryo behaviour continues until  sometimes 4 cell or even morula stage of the embryo when the actual zygotic or  embryo transcripts of the embryo genome begins.

When they latter begins the proteins produce for the physiology of the embryo are strictly derived from the transcriptional processes of the DNA of the embryo itself. In that case the embryo now becomes independent and fully human.

 

The brain wave theory suggests that it is only when the brain wave appears,  at which point it is assumed that the embryo has now developed a functional brain, that  is the time the embryo becomes human.

 

The Soul theory says it is only when the embryo acquires a soul, that it becomes human. Most Islamic theologians will suggest that this date will be 40 days after fertilisation.

 

The Primitive Streak theory. This theory  suggest that the organ primitive streak appears about  14 days after fertilisation. The primitive streak is unique because it brings organisation to a previously unorganised embryo. Before the formation of the primitive streak the embryo does not have head, tail or limbs, but just a  ball of cells. But after the appearance of the primitive streak it now has presumptive regions.

 

The Nervous System theory which is the next theory suggest that an embryo cannot be said to be fully human until it develops a nervous system. This theory  relies heavily on the fact that without a nervous system the embryo cannot feel pain. If there is no pain then there can be no actual life. In that case the embryo is considered to be a plant; it has the status of a plant because plants don't have no pain.

 

 

 

 

 

 

 

 

 


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