I wonder why apple's products are so expensive?
Answer: You pay the best for the very best and apple doesn't want to sacrifice the quality of there products for the price- Commented by Tim Cook CEO of apple. In Tim Cook's interview he noted that there are no mac's lower than $1,000 dollars.

I wonder how a person discovered that you can milk a cow?
Answer: There is no definite reason as this was discovered very very early in life, I believe the man or women saw a young calf suckling and the person thought why cant I? So they did.