Although previous studies of Olmec iconography have correctly recognized the importance of the jaguar element and its conceptual origins in the shaman jaguar trnasformation complex of beliefs, they have not explained why the Olmec expression of feline features should be different from their expression in other prehistoric American art styles sharing origins in the same complex of beliefs, nor why the olmec chose to express them in the form of an infant were jaguar, often hell in the arms of a seated adult male. IT is here suggested that the majority of the attributes of the were jaguar motif can best be explained by analogy with the congenital deformities manifested in and associated with multifactorial neural tube defects.