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Questions of A More Technical Nature

Which is Older, A or O?


QUESTION

I have been a long time follower and advocate of all of your work. However, there is one aspect that’s always been in the back of my mind. The following is from the Wikipedia entry for the blood type diet:

'Luiz C. de Mattos and Haroldo W. Moreira point out that assertions made by proponents of blood type diets that the O blood type was the first human blood type requires that the O gene have evolved before the A and B genes in the ABO locus; phylogenetic networks of human and non-human ABO alleles show that the A gene was the first to evolve. They argue that it would be extraordinary, from the perspective of evolution, for normal genes (those for types A and B to have evolved from abnormal genes (for type O).Yamamoto et al. further note: "Although the O blood type is common in all populations around the world, there is no evidence that the O gene represents the ancestral gene at the ABO locus. Nor is it reasonable to suppose that a defective gene would arise spontaneously and then evolve into normal genes.'

If any of this is true, then the very basis of the diet is flawed. Have you ever written a response to disprove these findings? and if so, how can these findings be so different to your own?



ANSWER

Another example of Wikipedia's selective inclusion policy. In molecular history, type A appears to be the 'oldest' blood type, in the sense that the mutations that gave rise to types O and B appear to stem from it. Geneticists call this the wild-type or ancestral allele. The type B mutation is a simple replacement of one of the letters of DNA in the ABO gene with another; what geneticists call a SNP(single nucleotide polymorphism) and everyone pronounces as 'snip.' The type O mutation is much more fascinating: It resulted from the complete loss of a letter in the ABO DNA and, like on a train when a boxcar is removed, all the other cars just move up by one. This type of mutation is called a frame shift and perhaps most amazingly, virtually every other known frame shift mutation is highly lethal. However, if you are type O, it made you.

However, as I've said, even on a molecular level genes move around a lot. Although Type A is the genetic ancestor, it appears to have disappeared in humans a very long time ago, and then 'resurrected' itself about 300,000 years ago. [REF: Kitano T1, Blancher A, Saitou N. The functional A allele was resurrected via recombination in the human ABO blood group gene.Mol Biol Evol. 2012 Jul;29(7):1791-6] This would be in accordance with the demographic evidence and would support a theory that hypothesized a more significant earlier numeric presence for type O.

More importantly, whichever theory about the evolutionary history of the blood types turns out to be right or wrong is irrelevant to much larger considerations you will never see included in any Wikipedia article about the diet. These are the physiological differences known to exist between the blood types at the phenotypic level (especially with regard to variations in digestive and immunologic capabilities) and strongly support the basic science behind the diets.

Wikipedia is well-known for its stance against alternative medicine and diet theories. Don't be fooled by those who would like to use this argument to invalidate the science behind the Blood Type Diets: the anthropology conjectures are simply speculations why those differences in physiology and immunology came about in the first place, and it is those physiologic differences that are of primary importance, not how they got there.




The Ask Dr. D'Adamo internet advice column ran from 1996 to 2009, at which time Dr. D'Adamo's teaching and programming responsibilities no longer allowed him to devote time and resources to directly answering visitor questions. However we've recently reorganized this treasure-trove of material and made it again available to his readership. He occasionally posts new entries. These are marked with a NEW tag.



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