The (In)tolerance of Milk in Humans

The (In)tolerance of Milk in Humans - Navarrete Rodrigo...

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Navarrete Rodrigo Navarrete Gina Jorgenson Wed. 10:00-10:50 Due: Jan. 30, 2008 The (In)tolerance of Milk in Humans Why can only some populations tolerate milk as adults? o The gene for milk tolerance [lactase enzyme] is missing from most adults in a given population o Typically, Western Europeans and some Africans are milk tolerant because of pastoral backgrounds in their lineage. o As we are weaned, our small intestine begins to create less and less lactase enzymes until it completely stops making the enzyme Typically this occurs by the age of 5 o No need to digest milk in a population where most of the food is meat Hunter-gatherers had no need for a lactase enzyme because of that fact What do these genetic changes tell us about the evolutionary history of milk tolerance in human populations? o Since it is believed and accepted that most early humans were nomadic hunter- gatherers, it is safe to say that very few drank milk as adults. This means that milk tolerance is a rather recent development in humans [in terms of evolutionary time, it’s the blink of an eye]. o It also means that humans only began to rely on milk as early as 9000 years ago. Humans who existed before then would have trouble digesting milk Would Neanderthals be able to tolerate milk as adults? o No, they wouldn’t because they effectively lacked the lactase enzyme. o They were typically carnivorous, eating large animals Although they had access to large animals, they did not domesticate animals so they probably never considered drinking the milk from an animal’s teat. o Although they lived in Europe, where most lactose tolerance in the world is centered, they inhabited the earth 30,000 to 130,000 years ago. This is far before the lactase enzyme was found in humans. What would happen if a population stopped drinking milk? o
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This essay was uploaded on 04/15/2008 for the course ANT 001 taught by Professor Mchenry during the Winter '08 term at UC Davis.

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The (In)tolerance of Milk in Humans - Navarrete Rodrigo...

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