WHY DOES THE BLOOD GROUP VARY FROM PERSON TO PERSON?

BLOOD GROUP -

Even though the blood of all the human beings looks alike, in reality, it is not so. Our blood is mainly composed of red blood corpuscles, white blood corpuscles, platelets, and plasma. It has been observed from microscopic investigations that molecules of antigens found on the surface of red blood corpuscles are different in different people. Antigen molecules are a kind of proteins that stimulate the production of antibodies. It is this difference in the antigen molecules that give rise to different groups of blood.

In the year 1900, Dr. Karl Landsteiner discovered two kinds of antigen - `A' and `B' type. He was awarded the Nobel Prize for medicine in 1930 for this discovery. Blood containing 'A' type antigen was classified as A group, while that containing 'B' type as B group. Subsequently, it was discovered that the blood of some people contains both A and B type antigens. This type was classified as AB group. The blood that contained neither A nor B type antigens was called O group. Thus the blood of all human beings has been divided into four groups. Studies made till now have revealed the existence of more than 200 groups of human blood.

However, as far as the transfusion of blood to any patient is concerned, only the aforesaid four groups of blood are important. Before transfusing blood to any patient, it is essential to get his blood group tested. It is very essential to match the blood of the patient with that of the donor before transfusion. It has been found that the blood of even real brothers and sisters may not be of the same group. On the other hand, the blood of two individuals belonging to two different states may be of the same group.

If the wrong blood transfused to the patient, he can die, because antigens of different classes cannot combine with each other. However, the blood plasma of one individual can be given to another because it is the same in everybody. Landsteiner and Alexander S. Wiener discovered another important blood antigen in 1940. This additional factor is called the Rhesus antigen or Rh factor.

Rhesus antibodies do not occur in naturally blood groups - both for recipients and donors. 'AB' group is called the universal recipients whereas `O' is the 'universal donor.

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WHEN DID THE FIRST ALPHABET APPEAR?

ALPHABET -

The origin and development of any language can be traced back to the rudimentary symbols the primitive people used in their verbal interaction. These symbols, when used over a long period, take an established pattern thus giving rise to a new language, But the growth of a language does not stop at oral communication a script for writing is also to be developed. But when did the first alphabet that enabled man to express himself in writing?

The earliest people used pictures for writing which we call pictograph. The stone age people used this form in their writing. In pictograph, a particular sign represents an object such as a tree or a bird which in turn communicates a specific meaning or idea. Ideas could be communicated through picture writing in the sense that the picture of a bird might mean flying.

The ancient Egyptians also used picture writing. But this form had its limitations. It required thousands of pictures, which were also called characters, to symbolize a few things. This drawback of pictograph led to the discovery of signs that represented sounds used in verbal communication. These signs representing different sounds were grouped differently to form new words. But when did the sound-signs first appear which we now call alphabet?

About 3500 years ago, the Phoenicians in the eastern Mediterranean, invented the first alphabet. Later the Greeks and Romans developed their own alphabet which were improvements of the Phoenician script. In fact, the word 'alphabet' is derived from two words alpha (a) and beta (b) which were the first two letters in the Greek alphabet. The appearance of the alphabet made it easier to create thousands of words using a few alphabets. For example, there are only 26 letters in English alphabet but just imagine how many words we make out of these 26 letters. Pictograph lacked this advantage since one picture represented only one meaning or idea.

Now, most of the languages in the civilized world have their own alphabet but the number of letters in the alphabet and their pronunciation differ from language to language.

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