BLOOD TYPES AND HUMAN EVOLUTION
Over the thousands of years of human evolution, four types of blood have developed. These apparently parallel the migrations and processes of civilisation in human society. The original human blood type of our hunter-gatherer ancestors, known as the ‘O’ type can be traced back over 40,000 years. The next type to appear was the ‘A’ type, which seems to accompany the rise of agricultural societies in the middle east around 20,000 years ago. Five to ten thousand years later, in the Himalayan highlands, the nomadic herders arose, and with them appears the ‘B’ type. Finally, only 1000 years ago, the ‘AB’ type became evident as a result of the tumultuous racial mixing that occurred with the many invasions of that time.

THE FOUR TYPES OF BLOOD
What actually determines the blood type is the presence on the red blood cells (and on the cell membranes of many other tissues) of surface markers called agglutinogens.
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In type O these are composed of chains of fucose molecules only.
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In type A the fucose chain ends with n-acetyl galactosamine.
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In type B the fucose chain ends in d-galactose.
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Type AB has both these molecules at the end of the fucose chain.

YOUR BLOOD TYPE DETERMINES HOW YOUR BODY REACTS TO THE FOODS YOU EAT
What makes this all relevant to life in general, as opposed to just those needing blood transfusions, is the existence of lectins - abundant and diverse proteins found in the majority of foods. Lectins are surface markers that aid inter-cellular adhesion. For instance, they help bacteria adhere to cell surfaces to facilitate infection and they enable our immune systems to identify and destroy those same organisms.

And lectins can react with blood type agglutinogens.

Consequently, depending on what lectins a food contains, some foods will be harmful to a person’s physiology, others will be neutral, and yet others may actually be beneficial. This is the basis of the Blood Type Diet, developed by Dr Peter D’Adamo.

THE BLOOD TYPING TEST
The ABO blood group of an individual is determined by testing red blood cells for the presents of the A and/or B antigen with commercial antisera. The presence of the antigen(s) is indicated by agglutination of the blood upon exposure to the antiserum.