Debunking the Paleo-Diet: A Matter of Perspective

The Paleo-Diet has recently been criticized by some anthropologists because it isn’t really “paleo.” For example, Cordain’s Paleo-Diet recommends that we consume more meat and vegetables and refrain from consuming grains. To be sure, the Paleo-Diet is based on the idea that humans should be “true” to their biology and consume foods that we consumed for 99% of our evolutionary history: meat and more meat.

Okay. I’ve exaggerated the Paleo-diet’s emphasis upon meat. To be fair, the “Paleo diet,” as presented by Cordain et al. (2005),  recommends a varied diet that relies upon plant-based and animal-based macro-nutrients (viz., carbohydrates, fats, and proteins). The diet, however, does not encourage consumption of grain or dairy products because they are recent foodstuffs and do not align with our biology. Proponents of paleodiets, then, suggest that humans have not been eating grains long enough to have adapted to them. “There hasn’t been enough time to evolve into a grain-eating species”, they exclaim, to which I respond: “Whaaat?!”

While it is true that humans did not rely upon grains prior to the Neolithic Revolution, and the refined grains that people rely upon today are approximately only one hundred and fifty years old, human adaptation can occur quite rapidly.

There is a very long list of recent adaptations within the human species that illustrates that evolution can, and does, occur rapidly from time to time. While Darwinian notions of evolution often come to mind, I will point out that Darwin wasn’t entirely correct. It is true that evolution can take place over long and gradual periods of time, sometimes it does speed up. In anthropology, we call this “punctuated equilibrium theory.” So, while it may have taken millenniums for dark skin to emerge among our ancestors, light skin appears to have evolved within the last 7000 years. Prior to the Agricultural Revolution, some 12,000 years ago, our jaws were much larger than they are now. Blue eyes emerged about 7000 years ago, lactose tolerance is a mere 5000 years old, and HIV resistance alleles (CCR5-Delta 32) are thought to be about 500 years old.

With that said, we need to be cautious about any claim that fails to understand the facts of evolution and misconstrues them. This doesn’t mean that the paleo-diet is wrong. There are issues with the diet. For example, the animal-based food paleolithic people would have consumed were wild, lean, and contained less saturated fat than the meat that one finds in a grocery store or even on independent free-range farms. At no point of time in prehistory did our ancestors consume meats that contained the number of saturated fats that our meats currently contain.

The presence of increased saturated fat (long chains of single bonded carbon atoms, saturated with hydrogen atoms) in our farmer-raised animals, as we know, is one of the causes of cardiovascular disease. Apparently, saturated fat has a higher melting point than unsaturated fat and therefore remains solid at body temperature. While the body relies on fatty acids as a source of energy (through ATP), long chains of fatty acids cannot cross what researchers call the blood-brain barrier. In other words, the central nervous system cannot use long chains of fatty acids (saturated fat) for energy – current research suggests that saturated fat may play a role in the onset of neurological conditions like Alzheimer’s disease. Moreover, saturated fat is responsible for raising cholesterol in an individual’s blood and thus increases a person’s chances of having a heart attack or stroke.

While the Paleo-Diet suggests that it emphasizes an evolutionary oriented diet, the majority of foodstuffs that one finds on the Paleo-Diet menu are all products of the Neolithic Revolution and domestication. It’s true. You are not going to find mangoes, tomatoes, and broccoli, for example, during the Paleolithic – at least in any form that you would recognize today.

“Really?”, you ask.

Yup, I bet you thought an almond was a nut, but it ain’t (pardon my grammar) – it’s a prune!

Although Warinner (a biochemical archaeologist) a offers good insight into the errors of the Paleo-Diet, ironically, she does arrive at a similar conclusion to the conclusion made by the Paleo-Diet: our current diets are maladaptive and are making us sick. First, for example, according to Warinner, our diets currently rely on three main species; namely, corn, soy, and wheat. Paleolithic peoples would have enjoyed dietary diversity – they would have exploited all kinds of plants, fruits, nuts and meat that were found in their local regions. Second, modern food preservation practices decrease nutritional values and impact our gut’s microbiome.

In contrast, Paleolithic peoples would have relied upon ripe food and benefited from its high nutritional content. Modern populations, however, rely on highly processed foods (e.g., bread, bagels, pasta, etc.) and this reliance is causing shockingly high rates of diabetes and obesity among populations. To be sure, any foods that were consumed before the 1800s would have been whole foods that were high in fiber, which plays an important role in regulating our metabolism and the release of sugar. So, in the end, both Warinner and Cordain would agree on one point: the modern human diet is harmful.

Comment

While I think Warinner’s work is awesome, I’ve got to point out that she has missed a few crucial points that have already been established in physical anthropology (the field of anthropology that emphasizes evolutionary biology and genetics). What did she miss? Well, many anthropologists argue that meat consumption played a crucial role in the evolution of humankind (e.g., Wrangham, 2009). Furthermore, if it was not for meat and eventually cooking meat, our brains would be pitifully small. In other words, if it wasn’t for meat consumption, the human race would still have small brains and would have invented nothing comparable to what we have today. I’ll tackle this topic, though, in the next post.

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