Chances are that if prehistoric Eurasians hadn't chosen to domesticate aurochs ca. 6500BCE, they'd have simply hunted them to extinction as they apparently had done to the woolly mammoth and a host of other mega-fauna. Actually, late and post-Pleistocene hunter-gathers are believed by some (notably Jared Diamond see "Guns, Germs, and Steel" NY: Norton, 1997) to be responsible for the disappearances of large vertebrates on every continent and island where they had existed for, in some cases, millions of years. Instead, various auroch subspecies were captured, bred, and interbred over the millennia into the varieties of cattle that we see today.
Today I am happy to announce here that the process begun by our agriculturist ancestors all those years ago, and which assures the continued existence of auroch DNA and it's diversification continues apace, and that we soon may see supermarket refrigerator cases burgeoning with bottles (sic) of Pre-Loaded Low Fat Cow Milk (my coinage).
Simply stated: Somebody done bred a cow that makes low-fat milk.
Scientists breed cows that give skimmed milk-News-UK-Science-TimesOnline