Fig. 4
Schematic diagram showing the area required for total calories (7.3 × 105 kcal/year) to support one person per year. a Hunter-fisher-gatherer societies in the Jōmon era generally required larger areas (more than 100 ha (1 km2)) due to low production density. In contrast, b chestnut production by hansaibai could require only 1.5 ha due to high production density in Jōmon era. This value is only sixth times that (0.25 ha) required by rice production in the Yayoi era (c). Thick black of outer frame lines represent the Jōmon society while the red dotted lines represent the Yayoi society. Green squares represent high production density (b, c) while purple squares show low production density (a). In general, Jōmon societies were characterized by low population density due to low food production density. In contrast, high production density of chestnut by hansaibai influenced by warm climate allowed the settlement of the Sannnai-Maruya site at 5.9 cal. kyr BP (b) while cool climate would have eventually collapsed the site at 4.2 cal. kyr BP, resulting in the dispersal of the population to smaller communities (a). Paddy rice-based societies in association with villages started at 2.9 cal. kyr BP in western Japan (c)