Move Over, Selfish Gene
Evolution traditionally has a problem with nice people. If only the fittest individuals survive, then those who are nice to others at their own expense will surely be weeded out. Yet cooperation is widespread in nature, from plants alerting each other to danger to dolphins cooperating to round up fish.
A decades-old idea called kin selection can explain some of this: if organisms ( 生物 ) have enough DNA in common, then they can further their own selfish genes by helping one another. Bees and ants have a system of reproduction which leaves colony members so closely related that they act almost as a single super-organism. And among any sexually reproducing species, parental care helps individuals pass on their genes.
But kin selection cannot explain why humans are so nice to strangers. One idea is that we have evolved to be super-cooperative because, over time, more cooperative groups have outcompeted less cooperative ones. But there generally isn’t enough genetic variation between groups to allow natural selection to favor more cooperative ones.
Some researchers think the solution lies in an idea called cultural group selection. Forget shared genes, they argue. Selection can favor cooperative groups if the people within them share enough culture. The idea is controversial because to work it requires that groups remain culturally distinct. As critics point out, people tend to migrate ( 迁移 ) between groups, which should homogenize ( 使同质化 ) ideas and customs. Those who back the concept counter that groups have ways to maintain their distinct culture, including a process called norm ( 准则 ) enforcement. Put simply, if someone migrates into a new cultural group, they are pressured into following the local rules because failing to do so leads to punishment.
Earlier this year, Mathew and Handley at Arizona State University published a study testing the idea. They sampled 759 people from four ethnic groups in Kenya who compete intensively for land, water and livestock. The pair estimated that genetic differences between individuals from different groups was generally less than 15%. Cultural practices and beliefs varied much more, by 10% to 20%. People cooperated most with members of their own group, as cultural group selection predicts, and to a lesser extent with members of other groups whose norms most closely matched their own. That makes sense if culture rather than genetics is what matters. “I think this is one of the most explicit tests of cultural group selection theory so far,” says Mathew.
Not everyone is persuaded. Krasnow at Harvard University sees no theoretical flaw with the idea, but says that some of his research undermines it. He has found that people don’t just enforce the rules within their group, but also punish people from other groups who fail to follow their own group’s norms. Mathew counters that it is reasonable to enforce the norms on outsiders as a step towards incorporating ( 使并入 ) them into your cultural group. “This is often how empires expand,” she says.
1 ． The example of bees and ants is used to ________.
A ． highlight the significant role of reproduction
B ． demonstrate the efficiency of a super-organism
C ． reveal why parents care about their selfish genes
D ． explain the cause of organisms helping one another
2 ． For the idea of cultural group selection to work, a pre-condition is that ________.
A ． cooperative groups have a larger chance of survival
B ． genetic variations in the same cultural group are small
C ． cultural differences are weakened with people migrating
D ． cultural distinctiveness can be preserved with certain methods
3 ． The text is developed mainly through ________.
A ． sorting information into different topics
B ． narrating events in time order
C ． presenting doubts and exploring answers
D ． discussing similarities and differences
4 ． We can learn from the passage that ________.
A ． culture plays a more significant role in choosing cooperators
B ． being selfish is of vital importance for an individual to survive
C ． Mathew’s study result contradicts what cultural group selection predicts
D ． people joining a new group will be punished for not keeping their own culture
1 ． D
2 ． D
3 ． C
4 ． A
【分析】
本文是一篇说明文。文章主要通过提出疑问和探索答案来阐述文化在选择合作者时起着更重要的作用的观点。
1. 推理判断题。根据第二段 “A decades-old idea called kin selection can explain some of this: if organisms ( 生物 ) have enough DNA in common, then they can further their own selfish genes by helping one another.” （一个几十年前被称为 “ 亲缘选择 ” 的想法可以部分解释这一现象 : 如果生物体有足够多的共同 DNA ，那么它们可以通过帮助彼此来进一步发展自己自私的基因。）可推断，蜜蜂和蚂蚁的例子被用来解释生物体互相帮助的原因。故选 D 项。
2. 细节理解题。根据第四段 “The idea is controversial because to work it requires that groups remain culturally distinct.” （这个想法是有争议的，因为它要求各个群体保持文化差异。）可知，文化群体选择的理念能够发挥作用的前提是文化的特殊性能够通过一定的方法得以保留。故选 D 项。
3. 推理判断题。根据第三段 “But kin selection cannot explain why humans are so nice to strangers.” （但是亲缘选择不能解释为什么人类对陌生人如此友好。）第四段 “Some researchers think the solution lies in an idea called cultural group selection.” （一些研究人员认为解决办法在于一种叫做文化群体选择的想法。）以及最后一段 “Not everyone is persuaded.” （并不是每个人都被说服了。）可推断，文章主要通过提出疑问和探索答案来发展的。故选 C 项。
4. 细节理解题。根据倒数第二段 “That makes sense if culture rather than genetics is what matters. “I think this is one of the most explicit tests of cultural group selection theory so far,” says Mathew.” （如果重要的是文化而不是基因，那就说得通了。 “ 我认为这是迄今为止对文化群体选择理论最明确的测试之一， ” 马修说。）可知，文化在选择合作者时起着更重要的作用。故选 A 项。