Lactase Persistence
A vast majority of adults in the world do not have the gene for lactase, meaning they cannot properly digest lactose (Boyd & Silk 2018). Despite this, most infants have the gene for lactase, but the enzyme that allows for proper digestion of lactose is shut off as children are weaned (Check 2006). Although this is true, there are many populations in Africa and Europe in which production of the necessary enzyme is not shut off and adults can properly digest lactose; this is known as lactase persistence (Check 2006). While only certain populations can tolerate milk as adults, this can be attributed to their genetic and cultural histories that gave rise to the mutation that allows for the proper digestion of lactose. This mutation prevailed in these populations because they actively drank milk, which proves that Neanderthals could not have been lactase persistent and neither can populations that stop drinking milk due to an increased availability of other foods. While individuals from only some human populations can tolerate milk as adults, their cultural and environmental histories provide insight as to why. These populations, commonly found in Africa and Europe, can tolerate milk as adults because their ancestors were pastoralists (Check 2006). Pastoralists are people who keep and raise livestock, specifically cows (Boyd & Silk…show more content… The need for lactase persistence in these individuals would decrease as the consumption of lactose decreases. These individuals would not receive the benefits of the mutation that allows for proper digestion of lactose and selection will not favor the production of the enzyme. Ultimately, only populations that actively consume milk and rely on it for survival will retain their lactase
