Why Scientists Keep Circling Back to the Diets of Our Ancestors
- Destiny McLaren
- Jan 17
- 6 min read
Updated: Jan 20
Think back for a moment to your grandmother’s kitchen. The smell of coffee, a loaf of bread cooling on the counter, a big pot simmering on the stove, maybe a bowl of fresh fruit on the table. Meals were simple, home-cooked, and built around real ingredients — not labels, macros, or trends. And here’s the quiet question that lingers in that memory: why weren’t most people as sick, overweight, or metabolically broken then as they are now?
Over the last fifty years, we’ve had more nutrition experts, more diet books, more government guidelines, more “breakthrough” research, and more branded food advice than any generation in history. By now, you’d think we would have finally cracked the code. Yet chronic disease has climbed, waistlines have expanded, and confusion about what to eat has only deepened. If all this progress was supposed to make us healthier, why does it feel like we’ve gone backward?
By the late 1960s and 70s, Americans were not living pristine lifestyles — smoking was widespread, processed meats were common, daily movement had already dropped, and most people went to the doctor far less than we do today. And still, rates of obesity and metabolic disease were dramatically lower than they are now. Something in the food environment shifted after that era, and the consequences have been impossible to ignore.
What Does Optimal Health Mean?
In this context, optimal health isn’t perfection. It refers to patterns of eating that are consistently associated with lower risk of chronic diseases such as:
heart disease
type 2 diabetes
hypertension
obesity
certain cancers
It also includes better metabolic function and a healthier gut microbiome, which are now understood to play a major role in immunity, inflammation, and overall well-being.
Across many populations, diets centered on whole plant foods and fiber tend to support these outcomes. These foods help stabilize blood sugar, reduce chronic inflammation, improve cholesterol profiles, and feed beneficial gut bacteria.
No single diet guarantees perfect health — but when the same patterns show up again and again across cultures, time periods, and study designs, they become hard to ignore.
Why Ancient Patterns Keep Showing Up in Modern Research
Understanding this helps explain why many modern nutrition models — including this pyramid — place whole plant foods at the base while treating animal proteins as supportive rather than central, not because protein is unimportant, but because most humans historically met much of their nutrition from plants.
Not every hunt resulted in a feast. Even if they had the room for storage there was no refrigeration to keep meat from spoiling. The majority of meat was eaten in jerky form after the first few days. After all, a group of a few hundred tops can only eat so much. For most of human history, diets were built around:
vegetables, fruits, beans, grains, and roots
little to no processing
occasional animal foods
very little seasoning or sweeteners
This wasn’t ideology — it was simply how people ate before industrial food systems existed.
What’s striking is that modern research keeps pointing back to that same broad structure. Populations that eat this way — whether in traditional communities or in contemporary “Blue Zones” — tend to show lower rates of chronic disease and longer lifespans.
In other words, scientists aren’t “inventing” something new. They’re repeatedly rediscovering a pattern that humans followed for thousands of years.
How Guidelines, Industry, and Evidence Intersect
Public health agencies aim to translate complex science into practical advice for millions of people. That’s a difficult job. However, food and agriculture industries also play a major role in shaping national guidelines.
When powerful corporations have a financial stake in what people eat, messaging can subtly shift toward products that are profitable rather than optimal for health. One common result is a focus on individual nutrients — protein, calcium, fat — rather than whole foods and dietary patterns.
This can downplay the importance of fiber-rich plants and elevate refined grains or highly processed products. Recognizing this dynamic doesn’t require cynicism — just clarity. It helps explain why some official models don’t fully align with the strongest independent evidence.
What the Evidence Actually Shows
Large-scale studies such as the Global Burden of Disease Study, along with reports from WHO and FAO, consistently associate diets rich in vegetables, fruits, legumes, and whole grains with lower rates of disease and mortality worldwide.
Fiber is a key driver of these benefits. It nourishes gut bacteria, which influence immune function, inflammation, and metabolism. Reviews published in The Lancet and BMJ repeatedly show that higher fiber intake correlates with reduced risk of cardiovascular disease and type 2 diabetes.
Most nutrition research is observational, meaning it shows associations rather than strict cause and effect. But when those associations appear across thousands of participants, many countries, and multiple types of studies, the pattern becomes compelling.
Taken together, the evidence points toward one conclusion:
Diets centered on whole, minimally processed plant foods consistently support better long-term health.
A Practical Model: The Optimal Food Pyramid
Rather than counting calories or obsessing over macronutrients, a clearer way to think about eating is through a food hierarchy — one that mirrors both ancient patterns and modern research.
Base: Abundant Whole Plant Foods
This is the foundation of long-term health.
It includes:
vegetables of all kinds
whole fruits (not juice)
beans and lentils
whole grains (oats, brown rice, quinoa, barley, buckwheat)
roots and tubers (sweet potatoes, potatoes, carrots, beets)
herbs and spices
These foods are rich in fiber, micronutrients, and phytochemicals that support gut health, blood sugar regulation, inflammation control, and cardiovascular health. The broad, heavy base of the pyramid reflects that this is what most of our meals should be built around.
Middle Tier: Healthy Fats and Energy Foods (Daily, in moderation)
This layer supplies steady energy and essential fats.
It includes:
avocados and olives
nuts and seeds
small amounts of olive oil
potatoes and other roots (as supporting energy foods)
These foods provide natural fats that fuel the brain, support hormones, and contribute to heart health. They are meant to complement the plant-and-grain base, not replace it.
Upper Tier: Whole-Food Proteins (supporting, not central)
If desired, include small to moderate amounts of:
beans and lentils (as primary plant proteins)
tofu and tempeh
fish
eggs
poultry
modest dairy
small amounts of pork
It may come as a surprise, but if you are consistently meeting your nutrient needs by eating from the bottom two tiers, you do not need to rely upon the protein tier. These foods can complement a plant-centered diet and help meet protein needs, but they do not need to be the main or dominant source of protein nourishment. In the image, animal proteins appear visually smaller to signal proportion rather than importance — protein matters, but it does not need to sit at the center of every meal.
It’s also worth clearing up a common confusion here. In recent years, the ketogenic diet has often been marketed as “the way our ancestors ate,” sometimes framed as a modern version of a so-called “caveman diet.” In reality, that comparison is deeply misleading. While some early human populations did rely more heavily on animal foods — particularly those living in Arctic or sub-Arctic environments where plant foods were scarce — this was the exception, not the rule.
Across most regions where humans evolved and settled, traditional diets were far more plant-forward, built around grains, beans, roots, fruits, and wild vegetables, with animal foods used more sparingly. In other words, a meat-heavy, very low-carbohydrate pattern was not the historical norm for most of our ancestors. Understanding this helps explain why many modern nutrition models — including this pyramid — place whole plant foods at the base and treat animal proteins as supportive rather than central.
Tip: Ultra-Processed Foods and Refined Products
This includes:
sugary drinks
packaged snacks
refined grains
processed meats
These are best kept occasional, as frequent intake is associated with higher risk of obesity, diabetes, and cardiovascular disease.
Going back to our visual above, eat more from the bottom, less from the top.
Practical Tips for Incorporating This Model
Start meals with vegetables: Fill half your plate with a variety of colorful vegetables.
Choose whole grains over refined grains: Swap white rice for brown rice or quinoa.
Add beans or lentils regularly: Use them in soups, salads, or as meat substitutes.
Snack on nuts and seeds: Keep a small portion handy for a nutrient-dense snack.
Include fermented foods: Add yogurt or fermented vegetables to support gut health.
Limit processed snacks and sugary drinks: Replace with water, herbal teas, or whole fruit.
If consuming animal products, keep portions small: Use them as flavor enhancers rather than main dishes.
Global Research Highlights
The EPIC study (European Prospective Investigation into Cancer and Nutrition) found that higher fruit and vegetable intake is linked to lower cancer risk.
The Nurses’ Health Study and Health Professionals Follow-up Study in the U.S. showed that plant-based diets reduce risk of heart disease and diabetes.
WHO and FAO reports emphasize the importance of dietary fiber and whole grains in preventing non-communicable diseases.
Cochrane reviews confirm that increasing fiber intake improves cholesterol and blood sugar control.
These findings come from diverse populations, reinforcing the universal benefits of whole plant foods. Across many cultures, historical dietary models share similar core features: plants, whole grains, legumes, roots, and small amounts of animal products.
After decades of “expert” advice, endless fad diets, and ever-changing guidelines, perhaps the real question isn’t what we should eat — but who those guidelines were designed to serve.
Were they built primarily for public health… or for the industries that profit from what we consume?
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