Human's are familure with artificial selection for generations. There were always magazines around our house with pictures of a huge bulls acomponied by pages of statistics and percentages. I can remember dinners were my brothers and Dad talked about selection, bulls, and so on. After being so familure with artificual selection natural selection did not seem quite as schocking. That is probably why Darwin started Chapter I with domestic breeding and artificial selection, it's a dinner converstation, unthreating, and something that people are familuar with. He takes maticulous detail in expounding on how breeders take deomestic pegions and domestic dogs.