>If it's so powerful, why did it not take over the rest of the world, or at least the rest of Eurasia? You'd think just a few people having kids with foreign po

>If it's so powerful, why did it not take over the rest of the world, or at least the rest of Eurasia? You'd think just a few people having kids with foreign populations would make the gene conquer the whole planet? They had cows in other places as well, right? It's cooler in Europe. Food stays better longer there. For example the daily mean temperature in Prague in July is 20 C, with a low of 15 C, so you could easily keep a cellar below that. Cheese will keep for a while. Plus, there's often a nearby mountain range with a convenient glacier: https://en.wikipedia.org/wiki/Ice_trade#Pre-19th_century_methods https://en.wikipedia.org/wiki/Ice_trade#Pre-19th_century_met...