Short answers, pulled from the story.
The Codex Alimentarius has defined milk as the normal mammary secretion of milking animals obtained without addition or extraction since 1961. This standard governs the product globally and distinguishes it from other biological secretions.
A chance mutation allowing lactase persistence spread through northwestern Europe thousands of years ago. This genetic shift enabled some populations to continue producing the enzyme lactase into adulthood while other regions remained lactose intolerant.
Dairying began in Mesopotamia as early as 9000 to 7000 BC according to lipid residue analysis in prehistoric pottery. Domestic dairy animals reached Britain and Scandinavia after 4000 BC following their spread from Southwest Asia.
Hervey Thatcher invented the glass milk bottle called Thatcher's Common Sense Milk Jar in 1884. The New York Dairy Company potentially used the first glass bottle packaging in 1877 and the Express Dairy Company began production in England in 1880.
Louis Pasteur invented pasteurization in 1863 while on summer vacation in Arbois. The standard high temperature short time process uses 72 degrees Celsius for 15 seconds to kill pathogenic bacteria in milk.
Bovine growth hormone supplementation was sold to dairy farmers in the US since November 1993. This supplement has been banned in the European Union for reasons of animal welfare.