导读:狗狗和人类一直都是好朋友，为什么呢？狗和狼之间有什么关系呢？
Being friendly is in dogs’ nature and could be key to how they came to share our lives, say US scientists.
美国科学家说，狗狗的友善的天性可能是它们能与人类一起生活的关键因素。
Dogs evolved from wolves tens of thousands of years ago.
狗是在几万年前从狼进化而来的。
During this time, certain genes that make dogs particularly gregarious have been selected for, according to research.
根据研究，在这段时间里，某些使狗变得特别温顺合群的基因留了下来。
This may give dogs their distinctive personalities, including a craving for human company.
这可能使得狗狗具备一些特别的个性，包括非常喜欢和人类待在一起。
"Our finding of genetic variation in both dogs and wolves provides a possible insight into animal personality, and may even suggest similar genes may have roles in other domestic species (maybe cats even)," said Dr Bridgett vonHoldt of Princeton University.
普林斯顿大学的Bridgett vonHoldt博士说:“我们在狗和狼身上发现了一定程度的遗传变异，这有助于了解动物的性格，甚至类似的基因可能在其他的物种(甚至是猫)中也有作用。”
The researchers studied the behaviour of domestic dogs, and grey wolves living in captivity. They carried out a number of tests of the animals’ skills at problem-solving and sociability.
研究人员研究了家养狗和圈养的灰狼的行为特点。同时，他们对动物的解决问题的能力和社交能力进行了一系列测试。
These showed that wolves were as good as dogs at solving problems, such as retrieving pieces of sausage from a plastic lunchbox.
这些研究表明，狼和狗一样善于解决问题，比如从一个塑料午餐盒里取出一些香肠。
Dogs, however, were much more friendly. They spent more time greeting human strangers and gazing at them, while wolves were somewhat aloof.
但是，狗更友好，他们会更愿意向陌生人问好，并看着他们，而狼则有些冷漠。
DNA tests found a link between certain genetic changes and behaviours such as attentiveness to strangers or picking up on social cues.
DNA测试发现，某些基因与行为有一定联系，如对陌生人的注意力，或对一些暗示的反应。
Dr Elaine Ostrander of the National Institutes of Health, who was a co-researcher on the study, said the information would be useful in studying human disease.
美国卫生研究院的伊莱恩·奥斯特兰德博士也是研究人员之一，他说这些信息对研究人类疾病很有用。
Dogs were domesticated from wolves between 20,000 and 40,000 years ago.
2万到4万年前，一部分狼逐渐被驯化成狗。
This process began when wolves that were tolerant of humans sneaked into hunter gatherer camps to feed on food scraps.
这一过程始于以前狼偷偷潜入狩猎营地，以食物残渣为生。
Over the course of history, wolves were eventually tamed and became the dogs we know today, which come in all shapes and sizes.
狼最终被人类驯服，成为我们今天所知的狗，它们的形状和大小也有所变化。
"This could easily play into the story then of how these wolves leave descendants that are also ’friendlier’ than others, setting the path for domestication," said Dr vonHoldt.
vonHoldt博士说:“这也说明这些狼是如何脱离了自己的后代，而这些后代也一步步变得友好，从而为驯化提供了途径。”
