Hunter-gatherer populations eating ancestral diets: Zero documented vitamin deficiency diseases. No scurvy. No rickets. No pellagra. No beriberi. No kwashiorkor. These diseases don't exist in the archaeological or anthropological record for populations eating traditional animal-based diets. Agricultural revolution begins 10,000 BC. Grain consumption becomes primary calories. Suddenly these diseases appear in skeletal record: Rickets: Vitamin D and calcium deficiency. Shows up in early agricultural populations eating grain-heavy diets. Rare in hunter-gatherers. Scurvy: Vitamin C deficiency. Appears in populations relying on stored grains with minimal fresh meat. Unknown in populations eating fresh animal products. Pellagra: Niacin deficiency. Epidemic in populations relying on corn as staple. Never appears in meat-eating populations. Beriberi: Thiamine deficiency. Epidemic in Asian populations eating white rice. Unknown in meat-eating populations. Kwashiorkor: Protein deficiency. Occurs in populations eating plant-based diets with inadequate animal protein. The pattern: These "vitamin deficiency diseases" are grain-dependence diseases. They appear when populations shift from animal-based diets to grain-based diets. They disappear when populations add animal products back. Scurvy example: British Navy: Sailors on hardtack and grain get scurvy epidemic. Solution: Add lime juice (vitamin C). Better solution: Feed them salted beef like they did before grain rations. Beef contains vitamin C. Sailors eating salted beef don't get scurvy. But lime juice is cheaper than beef. So "vitamin C deficiency" becomes the diagnosis instead of "inadequate animal products." Rickets example: Industrial revolution: Children working in factories, eating bread. Rickets epidemic. Solution: "Vitamin D deficiency. Children need supplements or sunlight." Actual cause: Grain-based diet lacking animal products that provide vitamin D and calcium in bioavailable forms. Feed children meat, butter, and eggs: Rickets disappears. Feed children bread and suggest supplements: Rickets continues. Every "vitamin deficiency disease" is better understood as "grain-displacement disease." Grain displaces animal products. Animal products provide complete nutrition. Grain provides calories with incomplete nutrition. Result: Deficiency diseases that didn't exist when humans ate animals. Modern medicine medicalises this: "You have vitamin D deficiency. Take supplements." Alternative view: "You're eating grain instead of animal products. Eat meat and the deficiency resolves." Hunter-gatherers eating nose-to-tail animals: Complete nutrition. Zero deficiency diseases. Agricultural populations eating primarily grain: Multiple deficiency diseases requiring supplements. The deficiencies aren't random. They're predictable consequences of displacing animal products with grain. Vitamin deficiency diseases are modern inventions created by grain-based diets. They didn't exist before agriculture. They don't exist in populations eating ancestral diets. They're not evidence that humans need dietary diversity. They're evidence that grain-based diets are nutritionally incomplete.