Interesting fact:

Todays domesticated cows are thought to have descended from middle eastern aurochs. The first wild oxen were domesticated around 10,500 years ago. The last of those ox-like creatures died in Poland in 1627. Today an estimated 1.3 billion cattle are spread over the world. And these cows and bulls have an unexpected environmental impact: When cows digest food they produce methane gas. A lot of it. 250 to 500 liters per day to be exact! Different studies credit livestock with something between 18 and 51 percent of the greenhouse gas emission.