Another prominent example of recent evolution resides within the ability to drink and digest milk. Most human adults are incapable of digesting lactose and therefore milk. Babies are capable of drinking milk due to a gene that codes for lactase, which breaks down lactose. In people who are lactose intolerant, the gene essentially switches off after weaning. However, a mutation known as lactase persistence arose in recent human history that allowed lactase to be produced into adulthood. This trait likely provided a selective advantage to individuals with access to domesticated dairy animals, who consumed the unfermented milk. “Analysis based on the conservation of lactase gene haplotypes indicates a recent origin and high selection coefficients for lactose persistence, although it has not been possible to say whether early Neolithic European populations were lactase persistent… (J. Burger et al., 2006)”
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