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Food is the body's fuel. Now a study finds that the amount of energy in that fuel can depend not just on its calorie content—but on how it's prepared. And the research, published in the Proceedings¹ of the National Academy of Sciences, could explain an ancient leap in human evolution.

Food's energy value is usually measured before consumption². But Harvard scientists fed two groups of mice either meat or sweet potatoes and prepared the items differently: either whole or pounded, raw or cooked—to create a variety of diets.

The researchers then measured the mice. They found that pounded meat and potatoes caused more weight gain than raw food. And that cooking increased weight the most.

The extra calories cooking makes available may have allowed the survival³ of humans with larger bodies and more complex brains, starting almost two million years ago. Those physical changes required more energy, and exposing food to fire may have provided that boost⁴.

Of course, a legacy⁵ of evolution is that modern humans often gain too much weight. Which might be called a raw deal.

Thanks for the minute. For Scientific American's 60-Second Science, I'm Sophie Bushwick.

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1 proceedings
n.进程，过程，议程；诉讼(程序)；公报
参考例句：
He was released on bail pending committal proceedings. 他交保获释正在候审。 to initiate legal proceedings against sb 对某人提起诉讼

2 consumption
n.消费，消耗，消费额，消耗量，结核病
参考例句：
Consumption of oil has declined in recent years.石油消耗量在最近几年下降了。 The meat was condemned as unfit for human consumption.这种肉已被宣布不适宜人们食用。

3 survival
n.留住生命，生存，残存，幸存者
参考例句：
The doctor told my wife I had a fifty-fifty chance of survival.医生告诉我的妻子，说我活下去的可能性只有50%。 The old man was a survival of a past age.这位老人是上一代的遗老。

4 boost
n.鼓励，激励，提高；v.鼓励，使增强信心
参考例句：
This will be a great boost to the economy.这对于经济发展将是一个巨大的促进。 These changes will help to boost share prices.这些变化将有助于提高股票价格。

5 legacy
n.遗产，遗赠；先人(或过去)留下的东西
参考例句：
They are the most precious cultural legacy our forefathers left.它们是我们祖先留下来的最宝贵的文化遗产。 He thinks the legacy is a gift from the Gods.他认为这笔遗产是天赐之物。