What kind of evolutionary advantage did lactose tolerance have?

There are a very few amount of advantages of you having lactose intolerance but one is you have digestive problems it helps a little but the disadvatage is dosen't give all the nutrients refular milk gives you!

I am going to assume you meant lactose intolerance,, so i have written my answer based upon those who are lactose intolerant:
an evolutionary advantage is any trait that can increase the fitness of one person/group of people over another. this means that if someone has a trait that allows them to better obtain food or resources,, they would have an evolutionary advantage to better compete against another species or group of people. being lactose intolerant can allow you a better evolutionary advantage over those who dont in a couple ways. first off,, these people are more likely to live and thrive if dairy goes away. if dairy one day disappears,, most people who are not lactose intolerant will not know how to get those nutrients that the body needs that they had previously gotten from milk. these people would eventually die without these nutrients,, while those who are intolerant to lactose would continue to thrive because they have lived without these things their whole life and now how to get their needed nutrients.  along with that,, people with a lactose intolerance are better able to starve off predators if they needed to,, because all they would have to do is kill all the animals that produce dairy. those without a lactose intolerance would have to get rid of a lot more things in order to starve off those with a lactose intolerance.
let me know if you have any further questions
:)

Carbon monoxide is the answer: )