Why Is O+ Blood Type The Most Common Blood Type?

Posted on Mon, 28 Jul 2014

Question: hi and how are you?
could you please tell me why the O+ blood type the most common blood type?

thanks

Answered by Dr. Jyothi B L (1 hour later)

Brief Answer:
Blood group are universal donors

Detailed Answer:
Hi
Studies show that previously everybody had mostly O blood group in the ABO system and with evolution, other systems added. Probably O blood group added more evolutionary advantage to further reproduce. Eg: in malaria, cell to cell transfer of malaria parasite in RBC is less and this must have made the earlier people live longer and reproduce more.
Blood group O is common and necessary for survival, as they are considered universal donors.
Other blood groups evolved as other diseases started and conferred protection. Eg: Duffy blood group in malaria or even RBC morphology is changed to sickle cells to protect against malaria.
Simply considering ABO is more common because it is the most ancestral form and was necessary at that time. The A and B mutations have appeared in the last 20,000 years and has not spread to entire population.
Blood group type O existed in cro- magnon man too and other antigens came late and so still O more. Evolution of new blood groups started so that a single blood disease should not wipe out the whole population, especially if the pathogen is adapted to particular blood.
Hope I have answered your query. Any more queries would be happy to help again.
Regards.

Above answer was peer-reviewed by : Dr. Vinay Bhardwaj

Follow up: Dr. Jyothi B L (14 hours later)

hi and thanks for your answer. I asked that question cause my blood group is O+ but my mother's is B+ and my father's is A+. sometimes I wonder why mine turned O+ cause I have deppression and I've been told that people with the O blood group have a higher risk of developing deppression.

Answered by Dr. Jyothi B L (8 hours later)

Brief Answer:
Depression is not limited to O blood group.

Detailed Answer:
Hi,
You are welcome.
Your mother blood group might be bb or bo and your fathers might be aa or ao. So you had to be either ao, bo, ab or oo. So as your did not not inherit any a or b or both, you are O blood group. As both are Rh positive, you too are.

Your next question is difficult. 70% in the world are O+ve and 99.9% O+ve would not have depression. It is only a study which shows depression is common. Nothing has confirmed that O blood group would influence the brain in anyway to get depressed.
Be cheerful.
Hope it helps.
If you have not further clarifications, you can close the discussion and rate the answer.
Thanks for asking.
Dr. Jyothi BL.

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Above answer was peer-reviewed by : Dr. Prasad