棱台英语听力跟读训练材料

2020年12月29日发(作者：余汉谋)

英语听力跟读训练材料

Cooking Up Human Intelligence

So what makes the human brain so special? Actually, it
might not be that special after all.

Sliding Scales

In 2009, Dr. Suzana Herculano Houzel and her colleagues
showed that the human brain has the same density of nerve
cells as other primates. Comparing humans to smaller primates,
she claims that our brain is no bigger than it should be for
our body size. Still, given the distinctive way that primate
brains scale with size, we may have the most brain cells of
any mammal.

That being said, gorillas can grow to be three times our
size, but still have much smaller brains than ours.

Brain cells need more energy than most body cells.
Although the brain is less than 2 percent of the mass of the
human body, it consumes 20 percent of our resting metabolic
energy. Gorillas have to spend more than eight hours every
day eating to get enough calories to support their big body,
and they simply can’t afford a bigger brain.

Brain Food

So, then, how did human ancestors overcome this
limitation? Beginning with homo erectus, about two million
years ago, our ancestors couldn’t have afforded the
metabolic cost of their increasingly large brains if they ate
raw food like gorillas do.



Primatologist Richard Wrangham thinks that the invention
of cooking with fire is what made this growth in brain size
possible. Cooked food is easier to digest and yields more
calories. Cooking may have made the human brain possible, and
freed us from having to spend all day eating.

density n. 密度

distinctive adj. 有特色的，与众不同的

mammal n. [脊椎] 哺乳动物

metabolic adj. 变化的；新陈代谢的

n. 灵长类动物学家 (primatology的变形)

烹饪与人类的智慧

所以说是什么让人类的大脑如此特别？实际上，这或许根本就不
特别。

变化的幅度

在2009年，苏珊娜·埃尔库拉诺·乌泽尔博士和她的同事们展示
了人类大脑的神经细胞密度和其它的灵长类动物一样。与其它较小的
灵长类动物相比，苏珊娜博士称我们 的大脑与我们自身体型相比并不
算大。但考虑到灵长类动物大脑尺寸比例的独特方式，人类拥有所有哺乳动物中最多的脑细胞。

话虽如此，大猩猩能长到我们体型的三倍，但它们的大脑仍然比
我们小得多。

脑 细胞比其它身体细胞需要更多的能量。虽然大脑所占人体的比
重小于2%，但它却消耗我们静止时代谢能 的20%。为了给庞大的身躯
提供充足的能量，大猩猩每天要花费超过8小时的时间进食，所以它
们无法负担更大的大脑。



大脑的食物

所 以，人类的祖先又是如何突破限制的？从直立的人类开始，大
约两百万年前，随着大脑越来越大，如果人 类的祖先还像大猩猩那样
进食生的食物，那么他们将无法给大脑提供充足的代谢值。

灵长类动物学家理查德·兰厄姆认为发明用火烹饪，使得大脑生
长变大成为可能。烹煮的食物更容易消化 并且能产生更多的热量。烹
饪或许促动了人脑的形成，并将人类从整日进食的境况中解放出来。