Dairy Products

Nutrition

Mammals have highly specialized sweat glands, called mammary glands, which produce milk. Evolutionary researchers suggest that the production of this opaque white liquid evolved as a means to keep eggs moist and point to the egg-laying monotremes as evidence for this claim. Milk provides a highly effective means of delivering nutrients to mammalian infants, who cannot yet digest many types of foods that older members of the species consume. Milk also supplies infants with antibodies that boost the immune system. The composition and components of mammalian milk vary from one species to another, but all contain large amounts of protein, calcium, saturated fat, and vitamin C.

Digestion and Lactase

In order to consume dairy products, mammals must produce lactase. This enzyme breaks down the milk sugar lactose and enables digestion. Lactase is essential for infants of all mammalian species, as they receive key nutrients from their mother's milk. In humans, breast milk contains the proper balance of water, protein, fat, and sugar necessary for growth and development. Additionally, a 2007 U.S. Agency for Healthcare Research and Quality–compiled report for the World Health Organization showed [Page 170]that breastfeeding provides the infant greater immune health, lower chance to develop allergies, higher intelligence later in life, less chance to develop diabetes, decreased risk of obesity, and reduced risk of sudden infant death syndrome. While milk consumption is necessary for mammal infant growth and development, adult mammals, with the exception of humans, do not consume milk. Humans are unusual mammals because they not only consume milk as adults but they also consume the milk of other animal species.

Adult Consumption

For much of human history, the ability to digest dairy products was unnecessary beyond the age of weaning. As food foragers, ancient humans consumed vegetation and animal protein and procured food by gathering, hunting, scavenging, fishing, and beachcombing. With the rise of agriculture during the Neolithic revolution, which occurred independently in as many as seven or eight separate regions beginning around 10,000 B.C.E., human food consumption patterns forever changed. Groups that adopted agriculture replaced nomadic, food-foraging methods with sedentary, food-producing methods. Some of these groups also brought animals permanently into their settlements. Beginning in the Middle East and then spreading out both east and west from there, this domestication of animals is what led to adult human dairy consumption.

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