Origins and Evolution of the Western Diet:

Health Implications for the 21st Century

Loren Cordain et al

American Journal of Clinical Nutrition

Vol. 81, No. 2, 341-354, February 2005


There's no getting around it, this is a LONG article, and probably not the read for everyone. I posted this paper for a few reasons: (A) Because Loren Cordain has done so much to promote not only the Paleo Movement, but to raise awareness for human health. (B) He is a fantastic scientist, researcher, and writer. And, what he writes about is fact. (C) To give you, the reader, some scientific ammunition to shut someone down when they doubt the facts of the

Paleo ~ Primal Lifestyle.

This paper is an in-depth look at the implications of the foods commonly eaten and recommended in society today versus what was eaten during our Hunter-Gatherer period in history. Loren Cordain, author of The Paleo Diet, and seven other contributors, have constructed a detailed look at the problems ingesting these foods yield and the resulting negative results on human physiology. I have shortened the original manuscript, but I can be founding its entirety, along with the 172 scientifically cited references HERE



There is growing awareness that the profound changes in the environment (eg, in diet and other lifestyle conditions) that began with the introduction of agriculture and animal husbandry ≈10000 y ago occurred too recently on an evolutionary time scale for the human genome to adjust. In conjunction with this discordance between our ancient, genetically determined biology and the nutritional, cultural, and activity patterns of contemporary Western populations, many of the so-called diseases of civilization have emerged. In particular, food staples and food-processing procedures introduced during the Neolithic and Industrial Periods have fundamentally altered 7 crucial nutritional characteristics of ancestral hominin diets: 1) glycemic load, 2) fatty acid composition, 3) macronutrient composition, 4) micronutrient density, 5) acid-base balance, 6) sodium-potassium ratio, and 7) fiber content. The evolutionary collision of our ancient genome with the nutritional qualities of recently introduced foods may underlie many of the chronic diseases of Western civilization.



Genetic traits may be positively or negatively selected relative to their concordance or discordance with environmental selective pressures. In the affected genotype, this evolutionary discordance manifests itself phenotypically as disease, increased morbidity and mortality, and reduced reproductive success

Increasingly, clinical trials and interventions that use dietary treatments with nutritional characteristics similar to those found in preindustrial and preagricultural diets have confirmed the beneficial health consequences predicted by the template of evolutionary discordance theory.

With the advent of agriculture, novel foods were introduced as staples for which the hominin genome had little evolutionary experience. This allowed for quantitative and qualitative food and nutrient combinations that had not previously been encountered over the course of hominin evolution.


Although dairy products, cereals, refined sugars, refined vegetable oils, and alcohol make up 72.1% of the total daily energy consumed by all people in the United States, these types of foods would have contributed little or none of the energy in the typical preagricultural hominin diet.



In the United States, chronic illnesses and health problems either wholly or partially attributable to diet represent by far the most serious threat to public health.

  • Sixty-five percent of adults aged +20y in the United States are either overweight or obese, and the estimated number of deaths ascribable to obesity is 280,184 per year.
  • More than 64 million Americans have one or more types of cardiovascular disease (CVD), which represents the leading cause of mortality (38.5% of all deaths) in the United States.
  •  Fifty million Americans are hypertensive
  • 11 million have type 2 diabetes
  • 37 million adults maintain high-risk total cholesterol concentrations >240 mg/dL)
  •  In postmenopausal women aged >50 y, 7.2% have osteoporosis and 39.6% have osteopenia Osteoporotic hip fractures are associated a 20% excess mortality in the year after fracture.
  • Cancer is the second leading cause of death (25% of all deaths) in the United States, and an estimated one-third of all cancer deaths are due to nutritional factors, including obesity.



In the 5–7 million-year period since the evolutionary emergence of hominins and studied hunter-gatherers, there would have been no single universal diet consumed by all extinct hominin species. Rather, diets would have varied by geographic locale, climate, and specific ecologic niche. However, there are universal characteristics of preagricultural hominin diets that are useful in understanding how the current Western diet may predispose modern populations to chronic disease. Increasingly, clinical trials and interventions that use dietary treatments with nutritional characteristics similar to those found in preindustrial and preagricultural diets have confirmed the beneficial health consequences predicted by the template of evolutionary discordance theory.



Before the development of agriculture and animal husbandry, hominin dietary choices would have been necessarily limited to minimally processed, wild plant and animal foods. With the initial domestication of plants and animals, the original nutrient characteristics of these formerly wild foods changed, subtly at first but more rapidly with advancing technology after the Industrial Revolution. Furthermore, with the advent of agriculture, novel foods were introduced as staples for which the hominin genome had little evolutionary experience. More importantly, food-processing procedures were developed, particularly following the Industrial Revolution, which allowed for quantitative and qualitative food and nutrient combinations that had not previously been encountered over the course of hominin evolution. In contrasting, pre- and post-agricultural diets, it is important to consider not only the nutrient qualities and types of foods that likely would have been consumed by preagricultural hominins but to also recognize the types of foods and their nutrient qualities that could not have been regularly consumed before the development of agriculture, industrialization, and advanced technology. Food types that would have generally been unavailable to preagricultural hominins are: dairy products, cereals, refined sugars, refined vegetable oils, and alcohol. And although they make up 72.1% of the total daily energy consumed by all people in the United States, these types of foods would have contributed little or none of the energy in the typical preagricultural hominin diet. Additionally, mixtures of these foods make up the ubiquitous processed foods (eg, cookies, cake, bakery foods, breakfast cereals, bagels, rolls, muffins, crackers, chips, snack foods, pizza, soft drinks, candy, ice cream, condiments, and salad dressings) that dominate the typical US diet.


Dairy Foods

  • After weaning, the consumption of milk and milk products of other mammals would have been nearly impossible before the domestication of livestock because of the inherent difficulties in capturing and milking wild mammals and are therefore relative newcomers to the hominin diet.



  • Because wild cereal grains are usually small, difficult to harvest, and minimally digestible without processing through grinding and cooking, the appearance of stone processing tools in the fossil record represents a reliable indication of when and where cultures systematically began to include cereal grains in their diet.
  • Ground stone mortars, bowls, and cup holes first appeared in the Upper Paleolithic (from 40000 y ago to 12000 y ago), whereas the regular exploitation of cereal grains by any worldwide hunter-gatherer group arose with the emergence of the Natufian culture in the Levant ≈13000 BP.
  • Cereal grains were rarely consumed as year round staples by most worldwide hunter-gatherers, except by certain groups living in arid and marginal environments.
  • There was little or no previous evolutionary experience for cereal grain consumption throughout hominin evolution.
  • 85.3% of the cereals consumed in the current US diet are highly processed refined grains
  • With the invention of mechanized steel roller mills and automated sifting devices in the latter part of the 19th century, the nutritional characteristics of milled grain changed significantly because the germ and bran were removed in the milling process, leaving flour comprised mainly of endosperm of uniformly small particulate size.


Refined Sugars

  • The per capita consumption of all refined sugars in the United States in 2000 was 69.1 kg, whereas in 1970 it was 55.5 
  • This secular trend for increased sugar consumption in the United States in the past 30 y reflects a much larger worldwide trend that has occurred in Western nations since the beginning of the Industrial Revolution some 200 y ago 
  • The first evidence of crystalline sucrose production appears about 500 BC in northern India. Before this time, honey would have represented one of the few concentrated sugars to which hominins would have had access. Although honey likely was a favored food by all hominin species, seasonal availability would have restricted regular access.
  • In the past 30 y with the advent of chromatographic fructose enrichment technology in the late 1970s, it became economically feasible to manufacture high-fructose corn syrup (HFCS) in mass quantity.
  • HFCS is available in 2 main forms, HFCS 42 and HFCS 55, both of which are liquid mixtures of fructose and glucose (42% fructose and 53% glucose and 55% fructose and 42% glucose, respectively). On digestion, sucrose is hydrolyzed in the gut into its 2 equal molecular moieties of glucose and fructose.


Refined Vegetable Oils

  • In the past 90y, a striking increase in the use of vegetable oils occurred.
  • Specifically, consumption of salad and cooking oils increased 130%, shortening consumption increased 136%, and margarine consumption increased 410%.
  • These trends were made possible by the industrialization and mechanization of the oil-seed industry.
  • To produce vegetable oils from oil-bearing seeds, 3 procedures can be used: 
    • 1) rendering and pressing 
    • 2) expeller pressing
    • 3) solvent extraction.
  • Oils made from walnuts, almonds, olives, sesame seeds, and flax seeds likely were first produced via the rendering and pressing process between 5000 and 6000 y ago. 
  • Margarine and shortening are produced by solidifying or partially solidifying vegetable oils via hydrogenation, a process first developed in 1897 which produces novel transfatty acid isomers (trans elaidic acid in particular) that rarely, if ever, are found in conventional human foodstuffs.



  • In contrast with dairy products, cereal grains, refined sugars, and oils, alcohol consumption in the typical US diet represents a relatively minor contribution (1.4%) to the total energy consumed.
  • The earliest evidence for wine drinking from domesticated vines comes from a pottery jar dated 7400–7100 y BP.
  • Because of seasonal fluctuations in fruit availability and the limited liquid storage capacity of hunter-gatherers, it is likely that fermented fruit drinks, such as wine, would have made an insignificant or nonexistent contribution to total energy in hominin diets before the Neolithic.


  • The total quantity of salt included in the typical US diet amounts to 9.6 g/d and about 90%  comes from manufactured salt that is added to the food supply.
  • The systematic mining, manufacture, and transportation of salt have their origin in the Neolithic Period, and the earliest salt use is argued to have taken place in China, by 6000.
  • Collectively, this evidence suggests that the high salt consumption (≈10 g/d) in Western societies has minimal or no evolutionary precedent in hominin species before the Neolithic period.


Fatty Domestic Meats

  • Before the Neolithic period, all animal foods consumed by hominins were derived from wild animals. 
  • Beginning with the advent of animal husbandry, it became feasible to prevent or attenuate the seasonal decline in body fat (and hence in SFAs) by provisioning domesticated animals with stored plant foods.
  • Furthermore, it became possible to consistently slaughter the animal at peak body fat percentage.
  • Neolithic advances in food-processing procedures allowed for the storage of concentrated sources of animal SFAs (cheese, butter, tallow, and salted fatty meats) for later consumption throughout the year.
  • Technologic developments of the early and mid 19th century—such as the steam engine, mechanical reaper, and railroads—allowed for increased grain harvests and efficient transport of both grain and cattle, which in turn spawned the practice of feeding grain (corn primarily) to cattle sequestered in feedlots.
  • In the United States before 1850, virtually all cattle were free range or pasture fed and were typically slaughtered at 4–5 y of age.
  • By about 1885, the science of rapidly fattening cattle in feedlots had advanced to the point that it was possible to produce a 545-kg steer ready for slaughter in 24 mo and that exhibited "marbled meat".
  • Wild animals and free-range or pasture-fed cattle rarely display this trait.
  • Marbled meat results from excessive triacylglycerol accumulation in muscle interfascicular adipocytes. Such meat has a greatly increased SFA content, a lower proportion of n–3 fatty acids, and more n–6 fatty acids.
  • Modern feedlot operations involving as many as 100,000 cattle emerged in the 1950s and have developed to the point that a characteristically obese (30% body fat) 545-kg pound steer can be brought to slaughter in 14 mo.
  • Although 99% of all the beef consumed in the United States is now produced from grain-fed, feedlot cattle, virtually no beef was produced in this manner as recently as 200 y ago.
  • Accordingly, cattle meat (muscle tissue) with a high absolute SFA content, low n–3 fatty acid content, and high n–6 fatty acid content represents a recent component of human diets.









The novel foods (dairy products, cereals, refined cereals, refined sugars, refined vegetable oils, fatty meats, salt, and combinations of these foods) introduced as staples during the Neolithic and Industrial Eras fundamentally altered several key nutritional characteristics of ancestral hominin diets and ultimately had far-reaching effects on health and well-being. As these foods gradually displaced the minimally processed wild plant and animal foods in hunter-gatherer diets, they adversely affected the following dietary indicators 1) glycemic load, 2), fatty acid composition, 3) macronutrient composition, 4) micronutrient density, 5) acid-base balance, 6) sodium-potassium ratio, and 7) fiber content.


1. Glycemic load


  • Assesses blood glucose raising potential of a food based on both the quality and quantity of dietary carbohydrate.
  • Refined grain and sugar products nearly always maintain much higher glycemic loads than unprocessed fruits and vegetables.
  • Unrefined wild plant foods like those available to contemporary hunter-gatherers typically exhibit low glycemic indices.
  • Sugars with a high glycemic load that lead to Insulin Resistance are 39% of the total energy in the typical US diet.
  • Acute elevations in blood glucose concentrations, along with increases in hormones secreted from the gut, stimulate pancreatic insulin secretion causing an acute rise in blood insulin concentrations.
  • Substantial evidence has accumulated showing that long-term consumption of high glycemic load carbohydrates can adversely affect metabolism and health and may elicit a number of hormonal and physiologic changes that promote insulin resistance. 
  • Diseases of insulin resistance are frequently referred to as ‘diseases of civilization’ and include: obesity, coronary heart disease, type 2 diabetes, hypertension, and dyslipidemia.
  • In addition, myopia, acne, gout, polycystic ovary syndrome, epithelial cell cancers (breast, colon, and prostate), male vertex balding, skin tags and acanthosis nigricans can all be related to regular consumption of HGL foods.
  • In addition to high-glycemic-load carbohydrates, other elements of Neolithic and Industrial Era foods such as milk, yogurt, and ice cream, may contribute to the insulin resistance and underlying metabolic syndrome diseases.
  • Despite having relatively low glycemic loads, they are highly insulinotropic, with insulin indexes comparable with white bread.
  • Dietary fructose may contribute to insulin resistance via its unique ability among all sugars to cause a shift in balance from oxidation to esterification of serum nonesterified free fatty acids.
  • Although sugars and grains with a high glycemic load now represent a dominant element of the modern urban diet.
  • These foods were rarely or never consumed by average citizens as recently as 200 y ago.


Fatty Acid Composition

  • Fatty acids fall into 1 of 3 major categories: 1) SFA (saturated) 2) MUFA (monounsaturated) and 3) PUFA (polyunsaturated)
  • Additionally, essential PUFAs occur in 2 biologically important families, the n6 PUFA and the n3 PUFA.
  •  Substantial evidence now indicates that to prevent the risk of chronic disease, the absolute amount of dietary fat is less important than is the type of fat.
  • The Western diet frequently contains excessive saturated and trans fatty acids and has too little n3 PUFA than n6 PUFA.
  • n3 PUFA may reduce the risk of CVD via many mechanisms, including reductions in ventricular arrhythmias, blood clotting, serum triacylglycerol concentrations, growth of atherosclerotic plaques, and blood pressure
  • Higher dietary intakes of n3 fatty acids are also therapeutic in preventing or ameliorating many inflammatory and autoimmune diseases.
  • Although much of the early work on the link between diet and CVD focused primarily on dietary fats and their effect on total and LDL-cholesterol concentrations, there are many other dietary elements that can operate synergistically to promote atherosclerosis.
  • As was previously mentioned, carbohydrates with a high glycemic load encourage a proatherogenic blood profile by elevating triacylglycerols and small-dense LDLs, while reducing HDL cholesterol.
  • Atherosclerosis is not just a “plumbing” problem involving excessive LDL cholesterol in the blood from excessive dietary SFAs, but also from chronic inflammation, which is essential in the formation of atherosclerotic plaques.
  • A recent study suggested that the blood concentration of the inflammatory marker C-reactive protein (CRP) is a stronger predictor of CVD than is LDL cholesterol.
  • The 6 major sources of SFAs in the United States diet are fatty meats, baked goods, cheese, milk, margarine, and butter. Five of these 6 foods would not have been components of hominin diets before the advent of animal husbandry or the Industrial Revolution.
  • Because of the inherently lean nature of wild animal tissues throughout most of the year and the dominance of MUFAs and PUFAs, high dietary levels of SFAs on a year round basis could not have exerted adverse selective pressure on the hominin genome before the development of agriculture.
  • The trend toward a higher ratio of n6 to n3 PUFA was exacerbated as meat from grain fed cattle and livestock became the norm in the US diet over the past 100 y.
  • In the current US diet, the ratio of n6 to n3 PUFA has risen to 10:1, whereas the ratio in hunter-gatherer diets predominant in wild animal foods has been estimated to be between 2:1 and 3:1.
  • The invention of the hydrogenation process in 1897 (44) allowed vegetable oils to become solidified and marketed as shortening or margarine and as foods containing hydrogenated vegetable oils.
  • The hydrogenation process introduced a novel trans fatty acid (trans elaidic acid) into the human diet, which elevates blood cholesterol concentrations and leads to an increased risk of CVD.
  • Trans Fatty acids in the US diet are now estimated toconstitute 7.4% of the total fatty acid intake


 Macronutrient Composition

  • In the present US diet, the percentage of total food energy derived from the 3 major macronutrients is as follows: carbohydrate (51.8%), fat (32.8%), and protein (15.4%).
  • Current advice for reducing the risk of cardiovascular disease and other chronic diseases is to limit fat intake to 30% of total energy, to maintain protein at 15% of total energy, and to increase complex carbohydrates to 55–60% of total energy.
  • Both the current US macronutrient intakes and suggested healthful levels differ considerably from average levels obtained from ethnographic and quantitative studies of hunter gatherers in which dietary protein is characteristically elevated (19–35% of energy) at the expense of carbohydrate (22–40% of energy)
  • An increasing body of evidence indicates that high-protein diets may improve blood lipid profiles and thereby lessen the risk of CVD.
  • This resulted in significant decreases in total, LDL, and VLDL cholesterol and triacylglycerols and an increase in HDL cholesterol, beneficial blood lipid changes in type 2 diabetic patients,  improved metabolic control in patients with type 2 diabetes, improved insulin sensitivity and prevention of muscle loss, whereas hypocaloric, high-carbohydrate diets worsened insulin sensitivity and caused reductions in fat-free mass.
  • Meat-eating populations have been shown to maintain lower plasma homocysteine concentrations than non-meat eaters
  • Because protein has 3 times the thermic effect of either fat or carbohydrate and because it has a greater satiety value than do fat or carbohydrate, increased dietary protein may represent an effective weight-loss strategy for the overweight or obese.


Micronutrient Density

  • Refined sugars are essentially devoid of any vitamin or minerals.
  • Because vegetable oils and refined sugars contribute 36.2% of the energy in a typical US diet the widespread consumption of these substances, or foods made with them, has considerable potential to influence the risk of vitamin and mineral deficiencies.
  • Vitamin B-6 prevents the accumulation of homocysteine in the bloodstream. Elevated blood concentrations of homocysteine represent an independent risk factor for the development of CVD, stroke, and deep vein thrombosis.
  • Wild plant foods, known to be consumed by hunter-gatherers, generally maintain higher micronutrient concentrations than do their domesticated counterparts, as does the muscle meat of wild animals.
  • The Neolithic introduction of dairy foods and cereal grains as staples would have caused the average micronutrient content of the diet to decline. This situation worsened as cereal-milling techniques developed in the Industrial era allowed for the production of bread flour devoid of the more nutrient-dense bran and germ.
  • The displacement of more nutrient-dense foods (eg, fruit, vegetables, lean meats, and seafood) by less-dense foods (refined sugars, grains, vegetable oils, and dairy products) and the subsequent decline in dietary vitamin and mineral density has far reaching health implications, consequences that not only promote the development of vitamin- deficiency diseases, but also numerous infectious and chronic diseases.


Acid-Base Balance
  • After digestion, absorption, and metabolism, nearly all foods release either acid or bicarbonate (base) into the systemic circulation.
  • Fish, meat, poultry, eggs, shellfish, cheese, milk, and cereal grains are net acid producing, whereas fresh fruit, vegetables, tubers, roots, and nuts are net base producing.
  • Legumes yield near-zero mean acid values, which reflects an overlapping distribution from slightly net acid producing to slightly net base producing.
  • Salt is net acid producing because of the chloride ion.
  • The typical Western diet yields a net acid load estimated to be 50 mEq/d. As a result, healthy adults consuming the standard US diet sustain a chronic, low-grade pathogenic metabolic acidosis that worsens with age as kidney function declines.
  • Virtually all preagricultural diets were net base yielding because of the absence of cereals and energy-dense, nutrient poor foods…foods that were introduced during the Neolithic and Industrial Eras and that displaced base-yielding fruit and vegetable.
  • The known health benefits of a net base-yielding diet include preventing and treating osteoporosis, age-related muscle wasting, calcium kidney stones, hypertension, and exercise-induced asthma, and slow the progression of age and disease-related chronic renal insufficiency.


Sodium-Potassium Ratio

  • The average sodium content (3271 mg/d) of the typical US diet is substantially higher than its potassium content (2620 mg/d)
  • Three dietary factors are primarily responsible for the dietary ratio of sodium to potassium.

1.       First, 90% of the sodium in Western diets comes from manufactured salt (sodium chloride); hence, the sodium content of naturally occurring foods in the average US diet (330 mg) is quite low.

2.      Second, vegetable oils and refined sugars, which are essentially devoid of potassium, constitute 36% of the total food energy. The inclusion of these 2 foods into the diet displaces other foods with higher potassium concentrations and thereby reduces the total dietary potassium content.

3.      Third, the displacement of vegetables and fruit by whole grains and milk products may further reduce the potassium intake because potassium concentrations in vegetables are 4 and 12 times those in milk and whole grains, respectively, whereas in fruit the potassium concentration is 2 and 5 times that in milk and whole grains.


  • Taken together, the addition of manufactured salt to the food supply and the displacement traditional potassium-rich foods by foods introduced during the Neolithic and Industrial periods caused a 400% decline in the potassium intake while simultaneously initiating a 400% increase in sodium ingestion.
  • The inversion of potassium and sodium concentrations in hominin diets had no evolutionary precedent and now plays an integral role in eliciting and contributing to numerous diseases of civilization.
  • Diets low in potassium and high in sodium may partially or directly underlie or exacerbate a variety of maladies and chronic illnesses, including hypertension, stroke, kidney stones, osteoporosis, gastrointestinal tract cancers, asthma, exercise-induced asthma, insomnia, air sickness, high-altitude sickness, and Meniere’s Syndrome (ear ringing) (160 –170).


Fiber Content

  • The fiber content, (15.1 g/d), of the typical US diet is considerably lower than recommended values (25–30 g).
  • Refined sugars, vegetable oils, dairy products, and alcohol are devoid of fiber and constitute an average of 48.2% of the energy in the typical US diet.
  • Fiber-depleted refined grains represent 85% of the grains consumed in the United States.
  • Fresh fruit typically contains twice the amount of fiber in whole grains, and non-starchy vegetables contain almost 8 times the amount of fiber in whole grains on an energy basis.
  • Once again, the displacement of fiber-rich plant foods by novel dietary staples, introduced during the Neolithic and Industrial periods was instrumental in changing the diets that our species had traditionally consumed, a diet that would have almost always been high in fiber.
  • Diets low in dietary fiber may underlie or exacerbate constipation, appendicitis, hemorrhoids, deep vein thrombosis, varicose veins, diverticulitis, hiatal hernia, and gastroesophageal reflux.



In the United States and most Western countries, diet-related chronic diseases represent the single largest cause of morbidity and mortality. These diseases are epidemic in contemporary Westernized populations and typically afflict 50–65% of the adult population, yet they are rare or nonexistent in hunter-gatherers and other less Westernized people. Although both scientists and lay people alike may frequently identify a single dietary element as the cause of chronic disease (eg, saturated fat causes heart disease and salt causes high blood pressure), evidence gleaned over the past 3 decades now indicates that virtually all so-called diseases of civilization have multifactorial dietary elements that underlie their etiology, along with other environmental agents and genetic susceptibility. Coronary heart disease, for instance, does not arise simply from excessive saturated fat in the diet but rather from a complex interaction of multiple nutritional factors directly linked to the excessive consumption of novel Neolithic and Industrial era foods (dairy products, cereals, refined cereals, refined sugars, refined vegetable oils, fatty meats, salt, and combinations of these foods. These foods, in turn, adversely influence proximate nutritional factors, which universally underlie or exacerbate virtually all chronic diseases of civilization: 1) glycemic load, 2) fatty acid composition, 3) macronutrient composition,

4) micronutrient density, 5) acid-base balance, 6) sodium-potassium ratio, and 7) fiber content.

However, the ultimate factor underlying diseases of civilization is the collision of our ancient genome with the new conditions of life in affluent nations, including the nutritional qualities of recently introduced foods.