英语听力文摘 English Digest 715 如何构建更强的大脑（在线收听）

Building Bigger Brains

We humans pride ourselves on having large, supple brains. But while our brains are larger than those of most other animals, it appears that over time our presence can result in smaller-brained animals having cerebral growth spurts.

Growth Both Urban And Rural

Scientists have found that certain small mammals — including some species of shrew, vole, bat, gopher, mouse and squirrel — have larger brains when they live near or around people in both urban and rural areas.

For example, one study found that the brains of urban-dwelling white-footed mice and meadow voles are about six percent larger than their rural cousins.

Meanwhile, as habitats have become developed, rural dwelling shrews and bats have also evolved larger brains over the past century.

Human Selection Pressure

Scientists speculate that the larger brains of some city living animals are due to those critters having to adapt to and survive in places populated by lots of people. After all, it stands to reason that raising baby mice and voles in busy urban and suburban places requires as much brain power as possible.

As for the rural animals whose brains have grown, it could be that human development in rural areas has forced animals such as bats and shrews to forage farther afield, and that patrolling larger hunting grounds requires more brain power.

An important underlying point of this research is that even an organ as complex as the brain is capable of significant evolution over relatively short periods of time.

如何构建更强的大脑

我们人类以拥有大而灵活的大脑而自豪。但是，虽然我们的大脑比大多数其他动物的大脑都大，但随着时间的推移，我们的存在似乎会导致大脑较小的动物出现脑生长激增。

城市和农村的增长

科学家发现，某些小型哺乳动物——包括一些种类的鼩、田鼠、蝙蝠、地鼠、老鼠和松鼠——在城市和农村地区生活在人附近或周围时，大脑会更大。

例如，一项研究发现，居住在城市的白脚鼠和草地田鼠的大脑比它们的农村近亲大大约6%。

与此同时，随着栖息地的发展，在过去的一个世纪里，居住在农村的泼妇和蝙蝠也进化出了更大的大脑。

人类选择压力

科学家推测，一些城市生活动物的大脑变大是因为这些动物必须适应并在人口众多的地方生存。毕竟，在繁忙的城市和郊区饲养小老鼠和田鼠需要尽可能多的脑力，这是有道理的。

至于那些大脑已经长大的农村动物，可能是因为农村地区的人类发展迫使蝙蝠和泼妇等动物到更远的地方觅食，而巡视更大的狩猎场需要更多的脑力。

这项研究的一个重要基础点是，即使是像大脑这样复杂的器官，也能够在相对较短的时间内进行显著的进化。