阅读理解1_原创精品文档.docxVIP

Few ideas from social science have dug their way into the public imagination like Dunbars Number, the famous finding that we humans cant cope with a social circle much larger than 150 people.The average size of modern hunter-gatherercommunities,it’s been calculated, is 148.8. The average size of army companies through history, from the Romans to the USSR, hovers around 150.And the average number of people to whom Britons send Christmas cards, according to a 2003 study, is153.5. No wonder so many panic-merchants worry that online social networks will destroy society. To accumulate 1,000 Facebook friends, Dunbars Number suggests, is to violate a law as old as humanity itself. In fact, the panic-merchants are wrong: Social networks don’t replace offline friendships. Nonetheless, Dunbar’s work does suggest something troubling about modern friendship. For centuries - and especially since the Industrial Revolution- weve been uprooting ourselves from the communities in which we were born. Until recently, on arriving in a new place, youd inevitably lose your ties with the one youd left; youd be forced to invest fully in a new social circle. These days, however, thanks to email and Skype, you need never cut those ties. You never leave your old life behind， so your emotional investments are scattered. One consequence is that the people in your circle of150 are far less likely to know each other. Or, as Dunbar writes, “Our social networks are no longer as densely interconnected as they once were.”Anyone whos ever fled small-town life might respond: Thank God for that.After all, there wont be people who are always snooping (窥探) on your business. Yet it turns out that when close friends know each other, good things happen. For example,Dunbars research shows that people are more altruistic (利他的)toward each other in dense social networks. Why are densely linked friends better friends? In a dense network, an act of friendship is two things at once: an expression of an individual bo