Core Idea
Here’s a familiar tune.
Eat plants for health, cut the meat for the planet, and trust that beans, seeds, and a healthy serving of virtue will keep bodies and biosphere in balance.
From hospital trade rags to high-gloss vegan documentaries, the plant-based drumbeat is a relentless story, especially among the well-fed and well-meaning. It says that a future built around plants is both a nutritional upgrade and an ecological necessity, “meatless Monday” on a planetary scale.
But what if the story leaves something out?
What if human biology that was honed over hundreds of thousands of years for survival on the move didn’t get the memo about our new allegiance to lentils?
Counterpoint
It’s a myth that the ideal human diet is, or should be, primarily plant-based, that animal foods are a historical accident, at best a guilty pleasure, and at worst, a planetary crime.
Authority figures and influencers converge, reciting the benefits of plant proteins and ethical grocery shopping as if these alone are the key to longevity and planetary salvation.
But reality, it seems, is wily.
For most of our evolutionary journey, humans ate what they could. Sometimes this was seeds and tubers, sure, but always with an opportunistic eye for anything denser, richer, and more nutritious.
And when survival depended on it, humans went for nutrient-dense animal foods. Not only do these foods package up high-quality protein—essential amino acids in generous, easily absorbed bundles—but they also offer nutrients not easily unlocked from raw plant materials without chemical trickery or centuries of breeding.
No great ape, even the plant-chomping gorilla, turns its nose up at animal protein when it’s available.
Human guts, human teeth, and human metabolic machinery don’t resemble those of strict herbivores. Fatty acids, dense protein, and the building blocks for brains as well as bones aren’t fringe benefits. They’re what made us, us.
And here’s the kicker. Protein is not just a muscle-builder or a vanity macronutrient; it is the structural and functional main act in every cell, every organ, every waking or sleeping hour.
Meanwhile, our cultural allergy to animal foods is recent and, in many places, still mostly aspirational. The jump to cereal and grain staples fueled population booms (and waistbands), but not necessarily vibrant health.
If “we are what we eat” rings true, then why rebuild diets around carbohydrates, a non-essential macronutrient, instead of prioritising quality protein—the very thing the body cannot make for itself?
Thought Challenges
See what happens… if, for a week, intake is planned around high-quality protein—animal foods if appropriate, or the best whole-plant sources that can be combined—making up the majority of meals. Notice shifts not just in appetite but in mood, energy, and satiety. What changes?
Compare labels on the next grocery run… track how much processed grain and sugar sneaks into “plant-based” products versus the simplicity of eggs, cheese, the odd steak, or some tinned fish. Which foods actually deliver what the body cannot manufacture itself?
Closing Reflection
If ideas about food are mirrors, then the modern worship of plant-based eating isn’t just about what’s on the dinner plate—it’s about a longing for purity, certainty, and sometimes, for moral clarity.
But the body is messy, ancient, and choosy in ways ideology can’t tidy up.
Protein is not just another nutrient in the mix. It’s the old workhorse of survival and repair, the baseline need the body returns to, silently, with every breath and every meal.
Before reciting the slogans, let the evidence and the body’s lived feedback, shape the menu.
Clarity, after all, is better than comfort food.
Evidence Support
Leroy, F. (2023). The role of meat in the human diet: evolutionary aspects and nutritional value. Animal Frontiers, 13(2), 11–19.
TL;DR… anthropological and biological evidence that animal-sourced foods have been central to energy acquisition and physiological development in human evolution, citing fossil, dental, and stable isotope data. It finds that hunter-gatherer societies derive most of their dietary energy from animal-origin foods, with animal protein and fat providing superior energy returns compared to wild plant sources.
Relevance to insight… how human physiology and culture are shaped by reliance on animal foods, supporting the notion that nutrient-dense animal protein was pivotal to evolutionary fitness and cognitive development, and remains important today.
Luca, F., Perry, G. H., & Di Rienzo, A. (2010). Evolutionary adaptations to dietary changes. Annual Review of Nutrition, 30(1), 291–314
TL;DR… synthesises genetic, ethnographic, and metabolic data to show that major dietary shifts, especially the move from meat-rich to carbohydrate-rich food with agriculture, influenced insulin signaling and metabolic health. It emphasises that ancestral diets often contained substantially more protein and less carbohydrate than modern ones, and that genetic adaptations are still catching up to recent dietary changes.
Relevance to insight… human metabolism and genetic adaptations are rooted in higher animal-sourced protein, and that the agricultural, carbohydrate-rich diet is a recent disruption that may underlie chronic disease risks in the present.
Päivärinta, E., et al. (2020). Replacing Animal-Based Proteins with Plant-Based Proteins: Effects on Nutrients, Lipoproteins, and Diet Quality. Nutrients, 12(4), 994.
TL;DR… randomised dietary intervention, shifting protein intake from animal (70%) to plant sources (70%) increased fibre, reduced saturated fat, and improved lipoprotein profiles but led to lower total protein intake and possible nutrient gaps. The study warns that partial or full replacement of animal protein can challenge provision of complete proteins and essential nutrients.
Relevance to insight… recent clinical evidence is critical for evaluating the implications of protein source. It shows both benefits and trade-offs of plant-based diets but emphasises that animal foods deliver more complete and bioavailable protein, echoing the evolutionary context.
Leroy, F., Beal, T., De Mûelenaere, N., De Smet, S., Heinrich, F., Iannotti, L., ... & Stanton, A. (2025). A framework for adequate nourishment: balancing nutrient density and food processing levels within the context of culturally and regionally appropriate diets. Animal Frontiers, 15(1), 10-23
TL;DR… dietary nutrient density is reliably improved by including animal-source foods beyond a “threshold” of about one-fourth of total calories. It reviews data suggesting that processed foods and carbohydrate-heavy diets lower overall nutrient density and undermine health, highlighting the unique contribution of animal-sourced foods to micronutrient intake.
Relevance to insight… how animal foods optimise nutrient density—supporting the argument that a protein-centred diet is superior for metabolic health and that current processed, carbohydrate-based diets are historically unprecedented and risk-laden.
Iannotti, L. et al. (2024). Terrestrial Animal Source Foods and Health Outcomes for Vulnerable Groups: A Systematic Review. Frontiers in Public Health, 12, 1043035.
TL;DR… positive health outcomes from animal-source foods across life stages: improved maternal and child health, reduced anemia and stunting, better muscle mass in older adults, and improved cognition in children. Risks were context-dependent and mainly limited to specific populations or overconsumption.
Relevance to insight… strong, modern evidence for the essential role of animal foods in human nutrition, especially for vulnerable populations, echoing the insight that animal proteins cannot be wholly replaced by plant sources without health consequences.
Taken together, these studies confirm that humans are biologically, evolutionarily, and epidemiologically adapted to nutrient-dense animal foods, that protein prioritisation in the diet is supported by metabolic and health evidence, and that reducing animal protein intake below a threshold risks overall diet quality, especially for vulnerable populations.