General Description of the Paleodiet
In popular media such as Web sites, the paleodiet is defined in slightly different ways. Nonetheless, there are common themes in aficionados’ and practitioners’ description of the diet. All versions of the paleodiet promote the consumption of a diet that humans would have eaten at least c. 10,000 years ago (Fragoso, 2015; Sisson, 2015; Wolf, 2014). The paleodiet eliminates (Fragoso, 2015; Wolf, 2014)grains, dairy, and processed food, all of which are disparaged as having entered human diets in relatively recent times, and for which humans are held to be insufficiently evolved (in terms of optimal digestion and other forms of physiological function). Some popularly supported forms of the paleodiet are more restrictive than others; for example, some paleodiet supporters suggest eating raw food more frequently, while other paleodiet supporters accept cooking.
Scientific Perspectives on the Paleodiet
The paleodiet has come under increasing scrutiny by the scientific community. While some aspects of the paleodiet, such as its support of the eating of unprocessed food, has received broad support from scientists, the paleodiet as a whole has been heavily critiqued by scientists (Zuk, 2013). One general scientific critique of the paleodiet is its assumption that human adaptation to food has remained fixed for at least 10,000 years. The evolutionary evidence (Pritchard, Pickrell, & Coop, 2010)is that humans can, and have, adapted to their changed food supply in a much shorter timespan (for instance, by adapting rapidly to the consumption of cooked rather than raw food), meaning that the paleodiet—if it even existed—is not necessarily the optimal diet for modern humans.
Another scientific critique of the paleodiet is that its central assumption about the role of grains is wrong. Even though grains were not cultivated on a systematic basis until the Agricultural Revolution, there is evidence that early human populations nonetheless ate grains where they were available (Yang & Jiang, 2010). Moreover, the exact composition of the so-called paleodiet varied so widely from population to population that it might not make sense to speak of a single paleodiet at all (Zuk, 2013).
A third scientific critique of the paleodiet is that there is little evidence that the diet was, as its aficionados claim it is, optimal. Early humans ate what was available to them, constrained by location and technology; they died young and were subject to a host of diseases (Zuk, 2013). While early humans might have had superior bone density and other markers of physical health vis-à-vis modern human beings, such differences can be ascribed more to sedentary behavior and the changing of the gene pool rather than to changing diets.
Synthesis of Evidence
To critique the paleodiet solely on the basis of biological evidence is to miss the context of the modern paleodiet movement. Any perusal of the popular paleodiet Web sites reveals that the people who practice and promote this diet are not merely concerned about food, but about lifestyle. Paleodiet supporters are particularly dismayed by the sedentary nature of modern life; in this sense, the paleodiet is not merely the reflection of a claim about human digestive physiology, but, more broadly speaking, the face of a movement that romanticizes the human past. For this reason, scientific critiques that focus solely on the biological aspects of the paleodiet, while necessary to debunk some of the specific claims made by supporters of the paleodiet, will not convince many people to stop eating in this way.
Any critique of the paleodiet ought to be separate the good from the bad. The paleodiet reflects some bad science, especially in its claims about the dangers of certain kinds of foods to whose consumption we have allegedly not adapted. However, the paleodiet can also be considered as one way—and perhaps not the most efficient or sustainable way—of consuming fewer calories and obtaining more micronutrients, while also orienting its followers towards more active lifestyles. The paleodiet is restrictive, and it might promote orthorexia or other forms of disordered eating, but it has to be weighed against the standard American diet (now rapidly becoming the standard global diet) of junk calories that has led to an explosion in obesity, diabetes, and cardiovascular disease. To dismiss the paleodiet solely as a fantasy, without pausing to consider the valid points made by supporters of the diet against the far more dangerous contents of the American diet and lifestyle, would be to commit both a scientific and a moral error.
Therefore, while the fringe claims of the paleodiet certainly deserve scientific debunking, the entire movement should not be summarily dismissed. One of the main concerns facing contemporary scientists is the global obesity epidemic, and the paleodiet is one possible tool in fighting this epidemic. At the very least, scientific critiques of the paleodiet ought to be more conscientious about acknowledging the general benefits of consuming less processed food, especially the junk calories that the paleodiet eschews.
The Paleodiet and Popular Conceptions of Evolution
One of the premises behind promotion of the paleodiet is that human evolution requires very long swaths of time in which to work. In particular, the tacit assumption of the paleodiet is that humans stopped adapting to changing dietary habits about 10,000 years ago—in other words, that we are not evolutionary optimized for a diet (a diet rich in grains, dairy, and other foodstuffs that have entered the human dietary repertoire since the Agricultural Revolution at the beginning of civilization) that we have in fact consumed for several centuries. As discussed earlier in this critical evaluation, there is compelling evidence that humans can adapt to changed diets in relatively rapid periods of time. Clearly, then, one possible critique of the paleodiet is its reliance on an unscientific notion of human adaptation.
- Fragoso, S. (2015). Everyday paleo. from http://everydaypaleo.com/
- Pritchard, J. K., Pickrell, J. K., & Coop, G. (2010). The genetics of human adaptation: hard sweeps, soft sweeps, and polygenic adaptation. Current Biology, 20(4), R208-R215.
- Sisson, M. (2015). Mark’s daily apple. from http://www.marksdailyapple.com/
- Wolf, R. (2014). The paleo diet works. from http://robbwolf.com/what-is-the-paleo-diet/
- Yang, X., & Jiang, L. (2010). Starch grain analysis reveals ancient diet at Kuahuqiao site, Zhejiang Province. Chinese Science Bulletin, 55(12), 1150-1156.
- Zuk, M. (2013). Paleofantasy: What evolution really tells us about sex, diet, and how we live. New York, NY: WW Norton & Company.