The original human blood type was O (originating in Africa), then came A with the development of agriculture (originating in the Middle East, between 25000 and 15000 BC, and spreading west into Europe), then came B with the development of herding (originating in the western Himalayas, and spreading east into China and India, between 15000 and 10000 BC), then came AB with the fusion of A and B types, resulting from the first Mongol invasion of Europe by Attila the Hun. These are well established facts in anthropology.
The discovery that the blood on the shroud was type AB was reported in Ian Wilson's book on the shroud. Basically this discovery has been overlooked because no one has seen its significance.
I came across the blood-on-the-shroud-can't-be-Jesus'-because-it's-AB argument in of all things a diet book by Dr Peter D'Adamo called The Eat Right Diet.