英语时差：人类最好的朋友（上）

Scientists are making great strides in understanding the genes that allow such a wide range of shapes, sizes and personalities in different dog breeds. Did you know domestic dogs were bred from wolves about 15,000 years ago? That's pretty recent in evolutionary terms. Isn't it? Very. Humans have sped up the diversification of dogs by selecting for particular physical or behavioral traits such as size, coat type, trainability, and hunting or herding ability. But dogs still show greater variety than any other domesticated animal, and for a long time this variance has largely been unexplained. A group of genetics researchers collaborated with dog breeders and veterinarians to study the DNA from 148 different dog breeds. With such a large sample of genes from very different kinds of dogs, they were able to identify regions in the dog DNA that are important in regulating some key traits that differ between breeds.