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What makes the human brain so special? Actually, it mightnot be that special after all.
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。
In 2009, Dr. Suzana Herculano Houzel and her colleagues showed that the human brain has thesame density of nerve cells as other primates. Comparing humans to smaller primates, she claimsthat our brain is no bigger than it should be for our body size. Still, given the distinctive way thatprimate brains scale with size, we may have the most brain cells of any mammal.
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。
That being said, gorillas can grow to be three times our size, but still have much smaller brains thanours.
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。
Brain cells need more energy than most body cells. Although the brain is less than 2 percent of themass of the human body, it consumes 20 percent of our resting metabolic energy. Gorillas haveto spend more than eight hours every day eating to get enough calories to support their bigbody, and they simply can't afford a bigger brain.
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足够的能量，大猩猩每天要花费超过8小时的时间进食，因此它们无法负担更大的大脑。
So, then, how did human ancestors overcome this limitation? Beginning with homo erectus, abouttwo million years ago, our ancestors couldn't have afforded the metabolic cost of their increasinglylarge brains if they ate raw food like gorillas do.
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足够的代谢值。
Primatologist Richard Wrangham thinks that the invention of cooking with fire is what made thisgrowth in brain size possible. Cooked food is easier to digest and yields more calories. Cooking mayhave made the human brain possible, and freed us from having to spend all day eating.
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。烹饪或许促进了人脑的形成，并将人类从整日进食的境况中解放出来。
