, however, are different from those of Paleolithic humans, which undermines the diet’s core premise.
During the 2.6-million-year-long Paleolithic era, the highly variable climate and worldwide spread of human populations meant that humans were, by necessity, nutritionally adaptable. Supporters of the diet mistakenly presuppose that human digestion has remained essentially unchanged over time.
While there is wide variability in the way the paleo diet is interpreted,
the diet typically includes vegetables, fruits, nuts, roots, and meat and typically excludes foods such as
, grains, sugar, legumes, processed oils, salt, alcohol or coffee.
The diet is based on avoiding not just processed foods, but rather the foods that humans began eating after the
The diet advises eating only foods presumed to be available to Paleolithic humans, but there is wide variability in people’s understanding of what foods these were, and an accompanying ongoing debate.
In the original description of the paleo diet in Cordain’s 2002 book, he advocated eating as much like Paleolithic people as possible, which meant:
55% of daily calories from seafood and lean meat, evenly divided
15% of daily calories from each of fruits, vegetables, and nuts and seeds
no dairy, almost no grains (which Cordain described as “starvation food” for Paleolithic people), no added salt, no added sugar
The diet is based on avoiding not just modern processed foods, but also the foods that humans began eating after the
The scientific literature generally uses the term “Paleo nutrition pattern”, which has been variously described as:
“Vegetables, fruits, nuts, roots, meat, and organ meats”;
“vegetables (including root vegetables), fruit (including fruit oils, e.g., olive oil, coconut oil, and palm oil), nuts, fish, meat, and eggs, and it excluded dairy, grain-based foods, legumes, extra sugar, and nutritional products of industry (including refined fats and refined carbohydrates)”;
“avoids processed foods, and emphasizes eating vegetables, fruits, nuts and seeds, eggs, and lean meats”.
Seeds such as
walnuts are eaten as part of the diet.
The aspects of the Paleo diet that advise eating fewer processed foods and less sugar and salt are consistent with mainstream advice about diet.
Diets with a paleo nutrition pattern have some similarities to traditional ethnic diets such as the
adapted to eating specifically those foods that were readily available to them in their local environments. These foods therefore shaped the nutritional needs of Paleolithic humans. They argue that the
Natural selection is a long process, and the cultural and lifestyle changes introduced by western culture have occurred quickly. The argument is that modern humans have therefore not been able to adapt to the new circumstances.
The agricultural revolution brought the addition of grains and dairy to the diet.
According to the model from the evolutionary discordance hypothesis, “any
populations have arisen because of a mismatch between
genes and modern lifestyles.”
Advocates of the modern Paleo diet have formed their dietary recommendations based on this hypothesis. They argue that modern humans should follow a diet that is nutritionally closer to that of their Paleolithic ancestors.
The evolutionary discordance is incomplete, since it is based mainly on the genetic understanding of the human diet and a unique model of human ancestral diets, without taking into account the flexibility and variability of the human dietary behaviors over time.
Studies of a variety of populations around the world show that humans can live healthily with a wide variety of diets, and that in fact, humans have evolved to be flexible eaters.
writes that the idea that our genetic makeup today matches that of our ancestors is misconceived, and that in debate Cordain was “taken aback” when told that 10,000 years was “plenty of time” for an evolutionary change in human digestive abilities to have taken place.
On this basis Zuk dismisses Cordain’s claim that the paleo diet is “the one and only diet that fits our genetic makeup”.
after the dawn of agriculture was caused by changes in diet, but others have countered that it may be that pre-agricultural hunter-gatherers did not suffer from the diseases of affluence because they did not live long enough to develop them.
Based on the data from hunter-gatherer populations still in existence, it is estimated that at age
15, life expectancy was an additional 39 years, for a total age of 54.
At age 45, it is estimated that average life expectancy was an additional 19 years, for a total age of 64 years.
That is to say, in such societies, most deaths occurred in childhood or young adulthood; thus, the population of elderly – and the prevalence of diseases of affluence – was much reduced. Excessive food energy intake relative to energy expended, rather than the consumption of specific foods, is more likely to underlie the diseases of affluence. “The health concerns of the industrial world, where calorie-packed foods are readily available, stem not from deviations from a specific diet but from an imbalance between the energy humans consume and the energy humans spend.”
Adoption of the Paleolithic diet assumes that modern humans can reproduce the hunter-gatherer diet. Molecular biologist
argues that “knowledge of the relative proportions of animal and plant foods in the diets of early humans is circumstantial, incomplete, and debatable and that there are insufficient data to identify the composition of a genetically determined optimal diet. The evidence related to Paleolithic diets is best interpreted as supporting the idea that diets based largely on plant foods promote health and longevity, at least under conditions of food abundance and physical activity.”
, whose diet was recorded for a single month, and one was on the
Due to these limitations, the book has been criticized as painting an incomplete picture of the diets of Paleolithic humans.
It has been noted that the rationale for the diet does not adequately account for the fact that, due to the pressures of
, most modern domesticated plants and animals differ drastically from their Paleolithic ancestors; likewise, their nutritional profiles are very different from their ancient counterparts. For example, wild
Trying to devise an ideal diet by studying contemporary hunter-gatherers is difficult because of the great disparities that exist; for example, the animal-derived calorie percentage ranges from 25% for the
of southern Africa to 99% for the Alaskan
Researchers have proposed that cooked starches met the energy demands of an increasing brain size, based on variations in the copy number of genes encoding for
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