英语翻译Contagious yawning may be a method of quiet communicatio

相互感染的打呵欠可能是一种无声的交流方式,我们祖先以此传递信息,提醒附近有一只饥饿的狮子。【“…scientists believe that yawning is an involuntary response to a stressful situation: When we yawn, we increase the blood flow to the brain, thus making us more alert。”"“Contagious yawning may be a method of quiet communication by which our ancestors spread the word that a hungry lion was nearby。”】以上是网上搜到的原文,详见http://mariopiperni。com/hate/right-wing-hate-delves-into-the-macabre。php