Generating Anthropological and Archeological Hypotheses in Okinawa through Agent-Based Simulation
agriculture displayed a higher population growth rate , the immigrant trait gene type and mtDNA haplogroup D4 were diffused through polygamous marriage . That is , for wider diffusion of the immigrant trait gene type and mtDNA haplogroup D4 to occur , it was necessary for immigrant neighbors to demonstrate use of agriculture and a higher population growth rate . Although whether there is a polygyny marriage has been unknown in Gusuku period , our simulation results suggest the possibility of the existence of a marriage institution in which people with immigrant trait genes and mtDNA haplogroup D4 can be distributed preferentially .
To discuss the diffusion process of agriculture in the Gusuku period , we investigated who had performed agriculture . The compositional proportion of descendants of those practicing agriculture showed a slight degree of mixing of native and immigrant descendants but that immigrant descendants constituted the majority at the early stage in cases that entailed slow diffusion of the agriculture ( Simulation case number 29 , Run 7 ) ( Figure 3 ). Both descendants thus came to account for most of those who engaged in agriculture as a result of marriage . These results suggest , as our first hypothesis , that agriculture was performed mainly by immigrants in the Gusuku period . In contrast , for cases demonstrating significant and rapid diffusion of agriculture , at the earliest stage , only the descendants of immigrants were the holders of agriculture . However , shortly thereafter , native descendants constituted the majority ( Simulation case number 35 , Run 9 ) ( Figure 4 ). Consequently , both descendant groups became the majority group through marriage . These results indicate that it is probable that even if agriculture was widely diffused among the native people , demographic transition could occur . These results suggest , as our second hypothesis , that agriculture was introduced to and performed mainly by native people in the Gusuku period . Both these hypotheses are probable . However , as described previously , considering that the reason for population explosion in the Gusuku period is the rapid and wide diffusion of agriculture , the latter hypothesis that the speed of agricultural diffusion was rapid and agriculture was performed mainly by native people is more probable .
81