As any cheese maker will tell you, it's not that hard to make cheese. You just take some fresh milk, warm it up a bit, and add something acidic to curdle it. Then, once it has cooled, you drain off the whey - the liquid part - and you're left with cheese.
But when did we figure out how to do this? According to a new paper in the journal Nature, at least 7,000 years ago. Since then, the process hasn't changed much.