RAT: Don't be too quick to squeal in revulsion: Rats are surprisingly intelligent and, actually, quite a bit like us. They giggle when tickled, they're sociable, they appreciate, even anticipate, sex. They also know their own intellectual limits, called metacognition, a trait thought limited to apes. In audio tests in which rats were rewarded for correct answers, given nothing for incorrect answers, and given a small reward for admitting "I don't know," they opted for reliable (albeit meager) "I don't know" treats when they lacked confidence in judgment. Not too shabby for filthy alley vermin.
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