system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How, when, and why did mankind find out cow milk was potable?
gpt
Human babies drink milk from their mothers.  It doesn't take a rocket scientist to realize that animal milk would be a good source of food.  The hard part would have been domesticating the cows so you could *keep* milking them.

A quick check shows that cows were first domesticated about 10,000 years ago.