As Figure 1.4 indicates, this theory asserts that all of a society's characterisitcs are ultimately due to just three things: (10 the influence of its biophysical and social environments, (2) the influence of our species genetic heritage, and (3) the influence of prior soical and cultural characteristics of the society itself.  The modelalso indicates that human societies have and effect both on their environments and our species genetic heritage (1991, pp. 17-18).