Something else happened in the Caucasus Mountains. Here milk that was being fermented also had strains of yeasts and these yeasts and bacteria produced a stable casein conglomerate that has become know as "Milk Kefir Grains"
These grains are added to fresh milk and allowed to ferment for 12-24 hours. The result is a complex blend of probiotics with a pH of around 4.5-5 so it is tangy and thick. It has a slight alcohol and acetyl smell and taste. If fermented closed it will be slightly effervescent.
Kefir can be purchased at most supermarkets and fresh food places but is often a cultured product and not one fermented from the casein grains.
The grains grow in volume across time so every 10 days or so you can split the culture and eat it, flush it or give it to a Kefir friend.
I ordered my Milk Kefir from Marilyn Kefirlady - you can order some your self. Marilyn delivered exactly what she promised and has a unique payment system that I really appreciated.
Just as suggested I added 2 cups of milk and fermented for 12 hours - pH was less than 5 and a slight separation of curds and a slight alcohol odor and taste. I am not sure I liked it but I am going to persist and try some different times and ratios of grains and milk and see what happens...stay tuned