Parts of the plants that were utilized were often discarded. Carl O. Sauer felt man had to be sedentary first. He favored SE Asia as the place of origin. But many nomadic peoples grow plants for food. The Near East center clearly did not develop in the tropics.
Vegetative reproduction is favored in the tropics.
Our system requires energy input, whereas gathering produces excess energy. Origins of particular crops Alphonse de Candolle - in 1882, wrote a book on the origin of cultivated plants. He based his ideas on historical writings, archaelogical information, ethnological data, linguistics etc. N. I. Vavilov - added genetics, chromosome studies, and anatomical data. He was interested in the presence of wild ancestors.