Jōmon Era Population Trends and Environmental Shifts

From Rising Seas to Flourishing Settlements

The Jōmon period (approximately 15,000 to 2,500 years ago) is a unique historical term specific to Japan, representing what can generally be called the prehistoric era of the Japanese archipelago, characterized by a diverse subsistence lifestyle involving gathering, fishing, hunting, and partial cultivation. Over this extensive period, the population of the Jōmon people did not continuously grow; rather, it fluctuated significantly through various phases.

Determining the exact number of inhabitants in the Japanese archipelago during this time remains challenging, yet it is widely reported that the population experienced a notable surge from the Early to Middle Jōmon period (approximately 7,000 to 4,500 years ago). Particularly, during the Middle Jōmon peak, the population across Japan is estimated to have reached more than 250,000 people. These estimates are primarily derived from calculations based on the number of settlement sites and pit dwellings (竪穴住居) found from this era, revealing particularly high population densities in eastern Japan. For example, in parts of the Kantō region, the density reached approximately 300 people per 100 square kilometers, suggesting that society had approached a critical threshold for sustaining traditional hunting-gathering economies.