Jim Meuninck points out that chimpanzees possess both
A and O types and gorillas are all type B. Perhaps
their diets might reflect and support the dietary
recommendation of Dr. D'Adamo? Perhaps not? This
would be more relevant information than just
suggesting that the AB origins in chimps and
gorillas in Africa negates their NON-African
origins in humans. Parallel evolution occurs at
different sites in different species because
necessity is opportunistic. Similar environmental
conditions can select for gene adaptations
in common ways. Especially since primates and
humans have many common genes, it does not seem
unlikely that similar blood types could have
evolved. If chimps are closer relatives to
humans than gorillas, then humans may have
only inherited Type O blood. Subsequently, both
seem to have evolved Type A though at different
times and places. Type B in humans then later was
selected for to fill an environmental niche for
which little selection pressure had existed
previously.

So, while humans didn't have to inherit Type A or
Type B from Primates in order to possess it now,
they had to inherit a POTENTIAL for these mutations
from their ancestors. And, due to favorable
environmental conditions, these mutations were
realized and retained by both the ancestors and
the progeny.