why do we have different blood types
scientists estimate that blood types
have been around for at least 20 million
years the doctors have only known about
them for the last 116 years before 1900
countless people died after they were
injected with the wrong blood but what
makes a certain blood type wrong for one
person but right for another part of the
reason has to do with proteins called
antigens on the surface of a red blood
cells that define your blood type for
example type A blood contains type A
antigens whereas type B blood contains
type B antigens but if you mix blood
types a and B together you'll start an
all-out war in the body your blood
plasma contains antibodies that police
the body for anything foreign including
antigens that don't match your blood
type when you inject the wrong antigens
antibodies will attack by attaching to
them which causes the blood to clump
these clumps clog blood vessels which
disrupts circulation and can prove fatal
it only takes a few milliliters of the
wrong blood to cause a serious reaction
so it's critical that you know your
blood type there are 35 blood group
systems in the world but yours likely
falls under the two most common groups
the group and the RH group together
these groups include the eight blood
types that dominate over ninety percent
of the world's population odds are that
you're either a positive or a positive
which account for about 65 percent of
all human blood types
however blood type can vary from one
location to the next for example type O
blood is far more common in the Western
Hemisphere of all types a and B show up
more often in the eastern hemisphere in
India for instance your odds of being
born B positive are four times greater
than in the US yet your chances of
developing the rare a B negative blood
type are less than 2% worldwide
scientists are still trying to figure
out why there are so many different
blood types and where they came from
we know that blood types are not unique
to humans dogs cats horses and monkeys
to name a few
also have them but animals usually
contain different antigens than humans
so don't go injecting pets with your
blood there's also a growing body of
research revealing that blood types play
a role in our defense or lack thereof
against certain diseases
for instance people with blood type A
are at a higher risk for some forms of
pancreatic cancer and leukemia as well
as smallpox infections heart disease and
severe malaria whereas people with blood
type O are far less likely to develop
severe malaria but they're more prone to
ulcers and ruptured Achilles tendons so
the next time you give blood take a few
minutes to contemplate just how bizarre
business it is when that blood
eventually enters another human being
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