To the best of my knowledge, most mammals cease to drink milk past infancy. Humans, on the other hand often substitute their mothers breast milk with that from other sources like cattle (or soy, forgive the joke).
Moreover, I have been taught that lactase persistence is a relatively recent phenomenon in many populations (evolutionarily speaking).
But is continued consumption of milk as an adult really necessary to stay healthy? I am guessing the nutrients that are found in say, cow's milk are not exclusive to it, and other dietary sources would exist for them.
Moreover, is it possible milk consumption can prove to be detrimental to adults in some form? (eg: http://www.ncbi.nlm.nih.gov/pubmed/22043817, It goes on to say that prostate and breast cancer patients should be cautioned about the possible promotional effects of commercial dairy products and their substitutes.)
Also, I would appreciate it if you could support your answer with literature references.
EDIT I am not looking for a yes or no, answer. I want an explanation that is grounded in an understanding of human physiology.