Recently a team of researchers has been studying questions about the history of milk in Europe. Their work to date has shown that lactase (beta-galactosidase) persistence (the retention of lactase activity after weaning that allows digestion of lactose into adulthood) likely occurred and became widespread thanks to a gene mutation in Neolithic times (5,000 to 10,000 years ago) in response to the consumption of a fresh cheese and not fresh milk.
In fact, recent analysis of perforated clay pot shards from over 7,000 years ago indicates the presence of milk-fat residues. This supports the notion that these pots were used to separate the high-lactose-containing whey from the fermented milk curd, which some arguably say is better described as a strained yogurt (naturally fermented), which may or may not have been cooked to facilitate whey separation.