Though not in the concept of 'yeast' defined by the modern science, the human being have been, since the ancient times, explicitly and implicitly aware of the presence of yeast which variously influences our daily life, have been selected the yeast based on our empirical rules, and have been used only the yeast which is suitable for the purpose of ours.
古来より人間は、現代の科学による「酵母」という概念ではないにしても、日常生活をさまざまに左右する酵母の存在を陰に陽に認識し、経験則によってこれを選択し、自分たちの目的にかなう酵母だけを利用するようにしてきた。