Since antiquity for more than 9000 years milk has been a part of the human diet. There is historical evidence that in Babylonia 4000 years BC people were able to produce cheese and butter. It is thought that green fig juice was used to turn the milk into cheese (curdle the milk) around the time Homer was alive. People started using animal rennet around 4th century AC. Most of the dairy products that we enjoy today were usually created accidentally.