英语时差：驯服宠物（上）

Have you ever played with a dog or cat and wondered why they are so tame? How did our ancient ancestors take wild, and potentially dangerous, carnivores and turn them into “man’s best friend”? In 1959 a Russian geneticist name Dmitry Belyaev began an experiment to try and understand how domestication worked. He started by selecting 130 of the captive wild foxes from a nearby fur farm that showed the least amount of fear and aggression towards humans. With each successive generation he selected which foxes would breed based solely on tameness. Only the foxes that behaved in the friendliest and tamest manner towards humans were selected to breed.