Journal on Policy & Complex Systems Vol. 2, Issue 2, Fall 2015 | Page 87

Journal on Policy and Complex Systems
because the effect of vertical transmission of pottery style is stronger than that of horizontal transmission ( Figure 6 , Simulation case number 194 ). The reason is the same as previous . Moreover , the proportion of immigrant-style pottery after 400 years varied depending on the speed of the diffusion of agriculture . The proportion of immigrant-style pottery holders in the cases of rapid diffusion of agriculture is higher than that in the cases of slow diffusion of agriculture ( Figure 6 ). These results are same as those of only the vertical transmission of pottery styles . Therefore , the difference between the vertical transmission of pottery and the vertical and horizontal seem not to be necessary important in our model .
However , in cases of the rapid diffusion of pottery styles , because of the reversibility of changes in pottery styles , there are some runs in which the immigrant-style pottery disappeared by stochasticity . Concretely , in cases of the rapid diffusion of agriculture and pottery styles , there are some runs in which the immigrant-style pottery was dominant and there are some runs in which the immigrant-style pottery disappeared . That is , in cases of the rapid diffusion of agriculture and pottery styles , the dominance of immigrant-style pottery had been by chance unlike the dominance of agriculture . Investigating the process of pottery-style diffusion in these cases , there is only a slight difference between slow pottery diffusion ( Figure 7 ) and rapid pottery diffusion ( Figure 8 ) in the proportion of native descendants with immigrant-style pottery holders . That is , in both cases , within the immigrant-style pottery holder group , native descendants were small .
In summary , our simulation generated new hypotheses of the diffusion process of pottery styles . These are as follows : ( 1 ) the high proportion of immigrant-style pottery holders needs polygamous marriage and rapid speed of agricultural diffusion . The result that the high proportion of immigrant-style pottery holders need rapid agricultural diffusion supports the assumption that the change of pottery styles is indivisible with agriculture ( Shinzato , 2002 ); and ( 2 ) in such conditions , immigrant-style pottery had been held mostly by immigrants and had not been widely diffused among native people .
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