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Several sources of evidence indicate that LP has evolved independently, in different parts of the world over the last 10,000 years, and has been subject to strong natural selection in dairying populations. Milk is a modest source of vitamin D but an excellent source of calcium, and the (Flatz and Rotthauwe 1973) may explain the high frequencies of LP observed in northern Europe, UVB levels in southern Europe, the Middle East, the Indian subcontinent, and Africa should be sufficient to avoid vitamin D deficiency (Jablonski and Chaplin 2010). 2006), all of these indirect approaches have poor sensitivity and temporal resolution, most are confounded by past demographic processes, and many are insensitive to selection acting on standing variation (Peter et al. In principle, none should be as powerful as direct comparison allele frequencies at different times in a continuous population.
We found significantly different branch lengths when comparing the rare deep-rooted A1b African lineage with the rest of the tree.Lactase persistence (LP) is a genetically determined trait whereby the enzyme lactase is expressed throughout adult life. Vitamin D is essential for calcium absorption in the gut and can be obtained from a few dietary sources (e.g., fish and eggs) or by the action UVB light on the skin, which photoconverts 7-dehydrocholesterol into cholecalciferol (vitamin D). In modern Iberians, the -13,910*T allele is found at a frequency of around 37% (Rasinpera et al. If these frequencies are also the result of natural selection after the establishment of the Neolithic, then the should not be invoked for this region of Europe.