The current state of our knowledge of the domestication and evolution of the grain amaranths: a critical standpoint

Sauer's hypothesis that the three grain amaranths originated from a single ancestor, and that artificial selection combined with hybridization with wild species resulted in the three grain amaranths, is corroborated by most recent authors. There is consensus that the three grain amaranths originated from Amaranthus hybridus. However, it appears that A. hybridus is polyphyletic. Only seed colour is predominantly present in the literature as a character of the grain amaranths domestication syndrome. There is no consensus on the degree of domestication of the grain amaranths. In the literature, there is considerable confusion regarding terminology, the way dates are displayed, concepts and geographical locations. However, we can conclude that there is consensus about the South American Andes and large parts of Mexico as geographical origins of domestication. Without doubt, the lack of good phylogenetic hypotheses for Amaranthus also blurs each attempt to clarify the evolution of the cultivated amaranths from their wild ancestors.