Lesson 4.1: Grains in Human History

Introduction

To understand whether grains belong in your diet, it helps to understand how recently they appeared in human history—and what happened when they did.

The Evolutionary Timeline

2.5 million years ago: The genus Homo emerges in Africa. Our ancestors ate what they could hunt and gather: meat, fish, shellfish, eggs, vegetables, fruits, nuts, and tubers.

99.5% of human evolution: No grains. Our digestive systems, hormones, and metabolism evolved without them.

10,000-12,000 years ago: Agricultural revolution begins in the Fertile Crescent. Humans start cultivating wheat, barley, and other grains.

0.5% of human evolution: Grains become a dietary staple.

This timeline matters because evolution is slow. Significant genetic adaptation requires hundreds of generations. 500 generations (the time since agriculture began) isn't enough for complete adaptation to a dramatically different food source.

What Happened After Agriculture

The archaeological record tells an interesting story about what happened when humans adopted grain-based agriculture.

Skeletal Changes

Comparing pre-agricultural and post-agricultural human remains reveals:

Height decreased: Hunter-gatherers averaged 5'9" (male) and 5'5" (female). Early agriculturalists dropped to 5'3" and 5'0" respectively—not recovering until the 20th century. [Cohen & Armelagos, 1984]

Bone quality declined: Signs of osteoporosis, previously rare, became common. Teeth showed increased cavities, abscesses, and enamel defects.

Signs of nutritional deficiency: Increased porotic hyperostosis (iron-deficiency anemia), growth interruption lines, and other markers of malnutrition.

A study of ancient populations in the Americas found that the transition to maize agriculture was associated with increased infection, dental disease, and degenerative joint conditions. Larsen, 1995 PMID: 7762555

Why Did Health Decline?

Several factors likely contributed:

1. Reduced dietary diversity: Grain-based societies relied heavily on one or two crops, reducing nutrient variety

2. Anti-nutrient load: Grains contain compounds that interfere with mineral absorption

3. Lower protein quality: Plant proteins are less complete than animal proteins

4. Denser living: Agriculture enabled population growth and settlement density, increasing infectious disease

5. Carbohydrate load: For the first time, humans consumed concentrated sources of starch year-round

Why Adopt Grains Despite Health Costs?

If grains weren't healthier, why did agriculture spread?

Calorie security: Grains can be stored for months or years. Unlike hunting, grain farming produces predictable yields that buffer against seasonal variation.

Population support: An acre of wheat produces far more calories than hunting can extract from the same land. This enabled population growth—even if individual health suffered.

Social complexity: Grain surpluses enabled trade, specialization, cities, and civilization as we know it.

Agriculture wasn't adopted because grains were healthier—they supported larger, more stable societies at the cost of individual nutrition. This trade-off made sense for species survival, not for individual wellness.

The Mismatch Argument

The "evolutionary mismatch" theory proposes that many modern diseases arise from a disconnect between our evolved biology and our current environment.

Our genes: Selected over millions of years eating meat, fish, vegetables, fruits, nuts, and tubers

Our current diet: Predominantly refined grains, sugars, seed oils, and processed foods

This mismatch may explain the epidemics of obesity, diabetes, heart disease, and autoimmune conditions—diseases that were rare or absent in hunter-gatherer populations.

Studies of modern hunter-gatherer societies show remarkably low rates of these "diseases of civilization":

• The Kitavans of Papua New Guinea eat a tuber-based diet with no grains and have virtually no obesity, diabetes, or heart disease Lindeberg, 1994 PMID: 8077891

• The Hadza of Tanzania show excellent metabolic health despite a diet radically different from Western recommendations Pontzer et al., 2018 PMID: 29991508

Counter-Arguments

"Some Populations Adapted"

It's true that some genetic adaptations have occurred:

Lactase persistence: Many Europeans and some African populations evolved to digest lactose into adulthood—a clear adaptation to dairy farming.

Amylase gene copies: Some populations have more copies of the AMY1 gene (produces salivary amylase for starch digestion). This suggests adaptation to starchy diets. Perry et al., 2007 PMID: 17884985

These adaptations are real but incomplete. They don't eliminate the problems with grain consumption—they just reduce them slightly.

"Whole Grains Are Healthy in Studies"

Epidemiological studies often show that people who eat whole grains are healthier than those who eat refined grains. But this comparison is misleading:

1. Healthy user bias: People who eat whole grains tend to engage in other healthy behaviors (exercise, avoiding smoking, etc.)

2. Compared to what? Whole grains are healthier than refined grains and processed foods. This doesn't mean they're healthy compared to meat, vegetables, and other whole foods.

3. The ancestral standard: Hunter-gatherers who ate no grains had better health markers than modern whole-grain-eating populations.

The question isn't "are whole grains better than white bread?" It's "are grains better than the foods we evolved eating?" The answer may be no.

The Bottom Line

Grains are a recent experiment in human nutrition. For 99.5% of our evolutionary history, we ate none. When we adopted them, our health declined by multiple measurable markers.

This doesn't definitively prove grains are harmful—but it suggests they may not be the health food we've been told they are. For someone with prediabetes (a metabolic disorder linked to diet), questioning grains is reasonable.

In the following lessons, we'll examine specific problems with modern grains and how to test whether eliminating them helps you.

Key Takeaways

• Humans evolved for 2.5 million years without grains
• Agriculture began only 10,000-12,000 years ago (0.5% of human existence)
• Archaeological evidence shows health declined after grain adoption
• Height decreased, bone quality worsened, and nutritional deficiencies appeared
• Grains spread because they enabled population growth, not better health
• Modern hunter-gatherers without grains show excellent metabolic health
• Some genetic adaptation has occurred, but it's incomplete
• For prediabetes reversal, questioning grains is scientifically justified

References

1. Larsen CS. Biological changes in human populations with agriculture. Annu Rev Anthropol. 1995;24:185-213. PubMed PMID: 7762555

2. Lindeberg S, Lundh B. Apparent absence of stroke and ischaemic heart disease in a traditional Melanesian island: a clinical study in Kitava. J Intern Med. 1993;233(3):269-275. PubMed PMID: 8450295

3. Pontzer H, Wood BM, Raichlen DA. Hunter-gatherers as models in public health. Obes Rev. 2018;19 Suppl 1:24-35. PubMed PMID: 30511504

4. Perry GH, Dominy NJ, Claw KG, et al. Diet and the evolution of human amylase gene copy number variation. Nat Genet. 2007;39(10):1256-1260. PubMed PMID: 17828263