Harris makes his argument in the context of evolution. (If you're confused about natural selection, check out the explanation on the right.) The relevance of milk, evolutionarily, regards its calcium content. Whether consumed by way of drinking milk or not, access to calcium had huge evolutionary advantages. Calcium-deficiency leads to osteoporosis (called rickets when it affects children). This leads to severe and inhibiting bone defects, and in females, a twisted pelvis that makes childbirth extremely dangerous for both the mother and the baby. Essentially, everyone around the globe needed (and still needs) a source of calcium. |
A Brief Explanation of Evolution: Natural selection, over time, favors those with the highest "fitness," which pertains to an organism's ability to survive and reproduce. Weak bones can make survival more difficult (especially because bones were often severely twisted, hindering movement and worsening overall health), and osteoperosis directly affects a female's ability to reproduce (and survive). So, over time, people who could absorb calcium and prevent these afflictions survived better than those who couldn't. They passed their genes on, so that today most of their descendents can also absorb calcium.
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In the United States, we often think of milk as the quintessential calcium source, but there are others too. Dark green leafy vegetables, legumes, or soybeans can all act as the main source of calcium, and in most places, they are. However, given Europe’s geographic features, like its soil and climate, significant production of dark leafy vegetables was difficult and impractical. So, the Europeans were left with milk for their principal calcium source, so natural selection strongly favored those who could drink milk and experience its positive effects.
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Lactose is important for digesting the calcium in milk, so Europeans with the lactase gene (which prevents lactose intolerance) fared much better than those without it. This increased their evolutionary fitness, so ultimately, the majority of Europeans had the lactase gene. However, lactase isn’t the only thing important for calcium digestion.
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Fun Fact:
The greatest amount of milk produced in one year was 59,298 pounds by a Holstein cow named Robthom Sue Paddy. |
Vitamin D3 also plays a large role in the ability to absorb calcium. Fair skin increases this ability by allowing certain wave lengths to penetrate skin, which is ultimately converted to D3. This helps with calcium absorption, but it also dramatically increases the risk of skin cancer and malignant melanoma.
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Check out these great dairy-free desserts!
Now for some desserts that are great sources of calcium!
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