Interesting bit of knowledge I gained from the article is that it's believed we only gained the ability to digest milk recently. Prior to that all humans were lactose intolerant.
I believe they meant all humans older than infants - adult onset lactose intolerance, otherwise it implies human lactation is a recent evolutionary trait that was reacquired or mothers made milk but their babies could not drink it.
The term lactose intolerant is commonly used as shorthand for adult onset.
One theory for the incredibly rapid spread of lactose tolerance is that during times of famine, lactose intolerant people in Northern Europe would drink fresh milk (out of desperation) and the resultant diarrhea would weaken them even more.