E.g. the distribution in the bones over male and female animals could not be explained by hunting alone. Even nowadays in the Near East one can collect at suitable spots two liters of wild grains per day per person. First grain species are barley and wild spelt. The knowledge that grains of corn will grow to new grain plants must have been known for a long time. The selection for the breeding of new varieties initially occurred almost automatically.
Loose grains falls off while cutting.
They are a waste, but the ones brought home and sowed again suffer less from this disadvantage. Simply sowing into fertile soil also stimulates different and better varieties. Natural barley has a flat spike in two rows, but in fertile soil a mutant is going to dominate automatically having a spike of six rows, resulting in an important increase of harvest yield. The food storage problem. Despite the simple principle, a good and guaranteed harvest every year requires the solution of many practical problems.