EXCERPT 1) Nonlinear additive series in African cultures. The counting numbers (1,2,3…) can be thought of as a kind of iteration, but only in the most trivial way. It is true that we could produce the counting numbers from a recursive loop; that is, a function in which the output at one stage becomes the input for the next: X n + 1 – X n + 1 . But this is a strictly linear series, increasing by the same amount each time — the numeric equivalent of a staircase. Addition can, however, produce nonlinear series, and there are at least two examples of nonlinear additive series in African cultures. …