Yogurt was discovered by accident when milk stored in animal stomachs fermented naturally.

The origins of yogurt date back to approximately 5000 BCE in Central Asia and the Neolithic Middle East. Nomadic tribes discovered that milk carried in pouches made from the digestive tracts of ruminant animals would curdle and thicken. This occurred because the stomach linings contained rennet and various wild bacteria that initiated the fermentation process.The primary bacteria involved are Lactobacillus bulgaricus and Streptococcus thermophilus. These microorganisms consume the lactose in milk and convert it into lactic acid. The increase in acidity causes the milk proteins to denature and coagulate into a solid mass. This process also acts as a natural preservative by inhibiting the growth of harmful pathogens.Historical records from the Roman Empire and ancient Greece mention the consumption of fermented dairy products for their health benefits. In 1905, Bulgarian scientist Stamen Grigorov was the first to identify the specific bacterium responsible for yogurt fermentation. Shortly after, Nobel Prize winner Ilya Mechnikov proposed that consuming yogurt was the secret to the longevity of Bulgarian peasants.Today, the World Health Organization recognizes yogurt as a nutrient-dense food that supports gut health. Modern production still relies on the same basic biological principles discovered by those early travelers. The accidental discovery of fermentation allowed ancient humans to store dairy calories for long periods without refrigeration.