Since cows (cattle) were first domesticated about BC 7000 , about 9000 yrs ago dont you think any health problems would have been noticed before now .
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re. your premise that because the Chinese and Japanese are lactose intolerant does not mean that Northern Europeans are . Similarily American aboriginals have different genetics that causes problems when they consume alcohol (think its liver enzymes) not all humans (different races/breeds) are the same and have developed in different ways , levels of intelligence is one that comes to mind.
