Interpolated map of the percentage of adults with a known lactase persistence genotype (-14010 G&gt;C, -13915 T&gt;G, -13907 C&gt;G or -13910 C&gt;T) in the indigenous population of the Old World. Circles mark the sample locations.
Own work (http://www.joeroe.eu/blog/lactose-intolerance-around-the-world/)

DataItan, Yuval (2010). "A worldwide correlation of lactase persistence phenotype and genotypes". BMC Evolutionary Biology 10: 36. DOI:10.1186/1471-2148-10-36. PMID 20144208. PMC: PMC2834688. ISSN 1471-2148.
Global Lactase persistance Association Database. Molecular and Cultural Evolution Lab. University College London (April 2012). Retrieved on 3 July 2017.&lt;/ref&gt;
Joe Roe