The roots of the different blood groups and the blood type diet are said to come from the Stone Age. D'Adamo claims that blood group O originated first: that of typical hunter-gatherers. At a later point in time, in the Neolithic Age, blood group A is said to have emerged, coinciding with the beginning of agriculture. Blood group B, whose origins lie in the steppes of Eurasia, arose as peoples intermixed. And blood group AB only emerged 1'000 years ago, from a combination of blood groups A and B.