Some interesting observations:
--Populations with the largest averages seem to cluster around the Equator, minus Indonesia.
--Latin American countries with higher levels of European admixture have averages in the same range as Iberia minus Uruguay.
--The United States has a smaller average than that of Europe. Considering that its three largest groups all have higher averages (European, African, and Latin America), this is also quite strange.
What environmental factors could account for the variation we see in Penis size? From an evolutionary perspective.