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Most large animals have to chew food extensively and form it into a mushy ball that's easy to swallow. Cooking makes a huge difference—it softens¹ the food and dramatically reduces eating time. Researchers calculated that if we lived like our non-cooking primate² cousins, we'd spend about 48 percent of the day eating. But modern humans spend only about 5 percent of the day chowing down. When our ancestors invented cooking, it gave them a major survival advantage.

So how long ago did our forebears start barbecuing?

The softer food available via cooking allowed for the evolution of smaller molars and a smaller jaw³. Researchers therefore compared the molars and body sizes of extinct hominids with modern humans and other primates⁴. Turns out that Homo erectus and Neanderthals had, and modern humans have, molars that are smaller than would be predicted by looking at general primate evolution. The finding is in the Proceedings⁵ of the National Academy of Sciences.

Based on the appearance of the smaller eating apparatus⁶, the researchers infer that humanity discovered the benefits of cooking about 1.9 million years ago. And we've been enjoying the convenience, speed and taste benefits ever since.

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

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1 softens
（使）变软( soften的第三人称单数 )；缓解打击；缓和；安慰
参考例句：
Iron softens with heat. 铁受热就软化。 Moonlight softens our faults; all shabbiness dissolves into shadow. 月光淡化了我们的各种缺点，所有的卑微都化解为依稀朦胧的阴影。来自名作英译部分

2 primate
n.灵长类（目）动物，首席主教；adj.首要的
参考例句：
14 percent of primate species are highly endangered.14%的灵长类物种处于高度濒危状态。 The woolly spider monkey is the largest primate in the Americas.绒毛蛛猴是美洲最大的灵长类动物。

3 jaw
n.颚，颌，说教，流言蜚语；v.喋喋不休，教训
参考例句：
He delivered a right hook to his opponent's jaw.他给了对方下巴一记右钩拳。 A strong square jaw is a sign of firm character.强健的方下巴是刚毅性格的标志。

4 primates
primate的复数
参考例句：
Primates are alert, inquisitive animals. 灵长目动物是机灵、好奇的动物。 Consciousness or cerebration has been said to have emerged in the evolution of higher primates. 据说意识或思考在较高级灵长类的进化中已出现。

5 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

6 apparatus
n.装置，器械；器具，设备
参考例句：
The school's audio apparatus includes films and records.学校的视听设备包括放映机和录音机。 They had a very refined apparatus.他们有一套非常精良的设备。