The Jomon people ate weeds (The beginning of permanent settlement and plant cultivation)

①13,000 years ago, both permanent settlements and the use of wild plants (Fabaceae or the bean family of plants and Poaceae or the grasses family, including cereal grasses) began.

　When pottery-making began 16,500 years ago, the pieces of pottery that were made simultaneously became sources of data. The remains of pit dwellings in southern Kyushu are evidence of permanent settlements. In the spaces within forests that were cleared for the purpose of building human settlements, plants such as those in the bean and grass families that bore small seeds thrived at the edges of the woods. The Jomon people, who observed birds eating these seeds, then began to use these plants as food sources for themselves. After long years of observing these plants, they realised that sprouts grew from these seeds, flowers bloomed when the sprouts matured, and then seeds were produced. Once they understood this cycle, they began cultivating these plants. Pottery played an enormous role in allowing them to utilise these plant seeds as a food source.

② Glycine (soybean) seeds gradually grow larger (Plant changes due to their cultivation by humans)

When one arranges the impressions of seeds in the genus Glycine (soybeans) discovered on pottery pieces in chronological order, one sees that they grow larger over time. This indicates a genetic change in these plants that emerged as a result of their cultivation by humans. Particularly in the Chubu region of Japan (Nagano prefecture and surrounding areas), the size of soybeans has been found to have increased as the settlements in that area grew larger over time from the Early to the Middle Jomon period.
The prevailing view in archaeology previously was that soybeans had been brought to Japan from China along with rice during the Yayoi period. However, research that discovered impressions of soybeans in pottery indicated that the cultivation of this food source began approximately 7,000 years ago in the Chubu highlands and in western Kanto.