Zebras & Ulcers: Debunking the Myth

Zebras do not get peptic ulcers in the wild. Their digestive system is highly adapted to a high-fiber, low-nutrient grass diet:

• Hindgut Fermenters: Large cecum/colon with microbial fermentation of cellulose → volatile fatty acids (energy).
• Continuous Grazing: 16–20 hrs/day → constant saliva (bicarbonate) flow buffers stomach acid.
• Low Stress (Evolutionary Context): No chronic psychosocial stress; predator stress is acute, not sustained.
• No NSAIDs, Alcohol, H. pylori (in wild).

The "zebras don't get ulcers" concept (popularized by Sapolsky) illustrates how chronic psychosocial stress in humans drives ulcer disease (via HPA axis, vagal tone, acid hypersecretion, mucosal defense impairment)—a mismatch between our ancient physiology and modern environment.