普特聽力：人類與烹飪
民以食為天，熱衷于美食的人類，也樂于追求更高層次的烹飪技巧，也許這就是為什么人類的智慧與美食會日益發達吧。
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 thedistinctive 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 restingmetabolic 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.
所以說是什么讓人類的大腦如此特別?實際上，這或許根本就不特別。
變化的幅度
在2009年，蘇珊娜·埃爾庫拉諾·烏澤爾博士和她的同事們展示了人類大腦的神經細胞密度和其它的靈長類動物一樣。與其它較小的靈長類動物相比，蘇珊娜博士稱我們的大腦與我們自身體型相比并不算大。但考慮到靈長類動物大腦尺寸比例的獨特方式，人類擁有所有哺乳動物中最多的腦細胞。
話雖如此，大猩猩能長到我們體型的三倍，但它們的大腦仍然比我們小得多。
腦細胞比其它身體細胞需要更多的能量。雖然大腦所占人體的比重小于2%，但它卻消耗我們靜止時代謝能的20%。為了給龐大的身軀提供足夠的能量，大猩猩每天要花費超過8小時的時間進食，因此它們無法負擔更大的大腦。
大腦的食物
所以，人類的祖先又是如何突破限制的?從直立的人類開始，大約兩百萬年前，隨著大腦越來越大，如果人類的祖先還像大猩猩那樣進食生的食物，那么他們將無法給大腦提供足夠的代謝值。
靈長類動物學家理查德·蘭厄姆認為發明用火烹飪，使得大腦生長變大成為可能。烹煮的食物更容易消化并且能產生更多的熱量。烹飪或許促進了人腦的形成，并將人類從整日進食的境況中解放出來。
【普特聽力：人類與烹飪】相關文章：
人類為什么不能穿墻「普特聽力文摘」01-26
普特英語聽力短文02-10
普特英語聽力短文《移動的手指》10-01
普特聽力材料：揭秘雜草重生的秘密01-14
「普特聽力文摘」年齡與嗅覺、味覺的關系01-15
普特聽力材料《加班有什么害處》01-13
普特聽力文摘《過量補充維他命有害嗎》03-15
「普特聽力短文」原來靜脈血管是這樣的01-20
普特英語聽力：為什么要接吻02-19