In 20 years, we will finally realize that humans evolved to drink only pure water.
"We propose that humans have evolved to withstand energy crises by decreasing their body size" http://www.nature.com/pr/journal/v64/n1/abs/pr2008135a.html
:humans evolved to modulate social behaviors like mating and parenting in response to specific environmental cues: http://link.springer.com/chapter/10.1007%2F978-1-4612-3760-0...
After just few seconds of search.. So apparently some scientists didn't get the memo.
Hopefully some day you will also evolve to be less nitpicky.
The majority of the human race lack the ability to digest milk (more specifically lactose sugar) once they are passed weaning.
It was a relatively recent mutation in some human populations (Northern Europe et al) that allows them to continue digesting lactose into adulthood.
They think this was because in Northern Climates where growing crops was more difficult milk and dairy products where a much larger source of calories than in other places as well as an excellent way of storing a valuable food product (Cheese however has relatively low levels of lactose at around ~1% compared to regular milk at ~5%).