There's got to be some place we got this in the ancestral environment that wasn't animal milk. Our nearest animal sibling primates don't drink animal milk, and presumably have the same requirement for them that we do. So, where do they get them? Consumption of bone marrow, perhaps?
Calcium rich foods include leafy greans, beans and fish and other seafood.
Lots of cultures around didn't have/don't have significant milk/dairy intake, those of us who can eat lactose into adulthood are mutants.
http://www.nature.com/news/archaeology-the-milk-revolution-1...
One of the explanations I've seen for why Europeans are white is to enhance this effect, because Europe gets comparatively less sunlight than other regions in which civilization initially spread, but was warm enough due to the gulf stream to support agriculture, which produces a diet lower in vitamin D. So between the comparatively lower sunlight and agriculture, Europeans needed to evolve to be able to generate more vitamin D from sunlight, which losing pigmentation helps with.
Vitamins A and D are present in the oils and livers of cold-water fishes and mammals. Vitamin C is obtained through sources such as caribou liver, kelp, whale skin, and seal brain; because these foods are typically eaten raw or frozen, the vitamin C they contain, which would be destroyed by cooking, is instead preserved.
But that doesn't fit into a modern Western diet.
Calcium from several vegetables.