Yogurt: Medium of Bacteria Evolution!

Imagine yourself as a Neolithic herdsperson in Central Asia around 6000 B.C.E. The goats are quietly grazing and you fall asleep in the sunshine. You have a milk-filled container fashioned from a goat's stomach.

The container basks in the sun with you as you sleep and when you awake, your goat's milk has transformed. Bacteria such as Lactobacillus Bulgaricus have transformed the milk into a tangy, thick concoction with an fresh smell.

Since it is the Neolithic, food is scarce, so you need to try to eat it. The taste isn't bad, and it doesn't make you sick. You even grow to like the taste. Maybe you even share your discovery with  other people. You have discovered yogurt. 

Of course, this is hypothetical, but historians really believe that yogurt originated this way.  Eventually people discovered that this curdled milk kept longer than regular milk which was a tremendous advantage.

Something interesting that I discovered about yogurt is that its bacteria provides information about the process of evolution. Since the genome of Lactobacillus Bulgaricus has been sequenced, scientists found that it was originally associated with plants because some of its genes metabolize sugars from plants. In an environment of fermented milk, these genes are not as useful so most likely the Neolithic  Lactobacillus Bulgaricus had more of these genes. In modern strains, the genes have been replaced by genes that are more adaptive to the fermented milk environment. 

The picture at the top shows yogurt made from sheep's milk on the right and cow's milk on the left. The yogurt on the left is Greek yogurt, so much of the liquid has been removed and it appears thicker. Also, it has a more creamy texture. The yogurt on the right has more graininess. Although yogurt originated from goat's milk, yogurt is today made from the milk of many animals including buffalo and camels. 

Yogurt has been associated with longevity and many health benefits. It is thought to strengthen immune systems and it is a great calcium source. Even Genghis Khan's hoards were allegedly kept fit for battle by eating yogurt. 

The tangy yogurt flavor is popular throughout the world now, especially when it is mixed with fruit jams and other sweet flavorings. I have a feeling that those tiny Lactobacillus Bulgaricus bacteria will never have problems finding warm milk environments in which to ferment and evolve. People will make sure that they exist.