After reading Allen and Wiley’s Evolutionary Perspective on Cow’s Milk Consumption and Health, I realized that, you know what, I still like milk. So much so, that I “got milk” to write this post.
As a 5’9” North Indian gal, drinking milk has never been a problem for me physically. I was quite intrigued to learn that this was because of an innate predisposition of lactase persistence. Yet, despite coming to understand the science behind the evolution of lactose, I admit to subjectively reading the studies and comparing them with my own experiences. Wiley distinctively defines the weak relationship between milk consumption and growth as in Danish children (Figure 5-2) emphasizing that in more developed countries, little to no effect was created. A stronger correlation was seen when a calcium-deficient population was tested. Maybe it’s my mom’s voice in my head, but “she made me a tall girl by making me drink two milkshake glasses of milk everyday”. And up until now, I believed her. Not only is the relationship flimsy, but, based on a US study conducted (p 124), nonexistent among girls! Nonetheless, there’s no doubt that in adequate moderation, milk provides many nutritional benefits. To some degree I find the implications of cancer and cow milk overstated, but pertinent to understanding the relative novelty of dairy products as a staple in the human diet. Whether cow, goat, sheep, soy, almond, or coconut, too many bio-cultural factors play a role in the action of chronic diseases.
So there must be a more biological reason why not only cow, but dairy consumption has steadily been increasing the past one hundred years or so, right? In my opinion, yes. And, I cannot explain myself without referring to the evolution of the human diet. As surprised as I was to see a whole chapter devoted to cow’s milk, I was more surprised on the short explanation of diet and nutrition provided in the text as it plays a large part of human evolution. But, this idea of adaptive taste preferences and aversions made me take note of the strength of all five senses and how they are capable of widening the “breadth” of foods humans consume. The age of agriculture and domestication introduced an entire new pallet of taste preferences in order to maintain a proper diet. The domestication of animals and the increase in dairy consumption led to stronger bones, particularly the teeth (http://milk.procon.org/view.answers.php?questionID=000977) promoting oral health. However, this revolution forced an irreversible change on the way humans consume food. Before the agricultural revolution, hunters and gatherers often ate hard, thick food which evolutionarily provided them with longer skulls. As food become more cooked and soft, skull and jaw sizes shrunk, more quickly than growing dentition. Ultimately this led, is still leading, to a “rise in occlusal abnormalities and malocclusion” (http://jn.nutrition.org/content/133/11/3893S.full). And, it hasn’t become better; despite an increase in milk consumption and its calcium’s benefit on preventing cavities, teeth decay is at an all-time high. And, oral health is reflective of an individual’s overall health, reiterating the subpar modern diet the modern world has fallen victim too.
In the end, I still like milk, even though it may not be natural, but it’s just another adaptation humans must evolve to as well as numerous other dietary and nutritional changes.