(cont) CONVEXITY and BIOLOGY (technical):1) In the presence of an upper bound, the function will end up concave (asymptotically pasting), even if it starts convex (hence the sygmoid shape).2) In the absence of an upper bound, the function is necessarily nonconcave, hence necessarily power-law style.3) Now my epistemic opacity problem: IF YOU DON'T KNOW THE UPPER BOUND, then you need to treat it as convex.