 Data from population genetics shows that the global distribution of allele frequencies in the human population is not discontinuous (Jorde &amp; Wooding 2004; Feldman &amp; Lewontin 2008) but clinal, meaning that human DNA sequences vary in a gradual manner over geographic space (Livingstone 1962; Serre &amp; Pääbo 2004; Barbujani &amp; Colonna 2010). Moreover, both genetic and phenotypic traits display what is called ‘nonconcordant’ clinal variation, meaning that different traits do not necessarily co-vary with each other; the pattern of how trait A varies across geographic space might be very different from the pattern displayed by trait B (Livingstone 1962; Goodman 2000; Jorde &amp; Wooding 2004).