12月29日，发表在《当代生物学》（Current Biology）杂志上的一项研究表明，当危险临近例如一条蛇出现时，黑猩猩能够识别出团队里哪些成员处于不知情状态，然后马上给它们发出警告，让其小心提防。
迄今为止，科学家认为只有人类才能知道团队里有些人“不了解状况”，这是属于人类的独有特征。而科学家发现当有蛇出现时，野生黑猩猩更有可能对新成员发出“小心提防”的警报信号，他们认为新成员可能不像群里的“老手”一样知道面临的危险。这一发现挑战了上述人类“自以为是”的看法。
科学家把一条假蛇放在乌干达黑猩猩经过的路上，看它们的反应。当一个黑猩猩发现了一条蛇，它马上发出“呼呼”的警告声，让组里的其他成员都可以听到。当其他成员赶到现场时，它们重复警告以确保新来的人知道这里有一条蛇。如果组里的成员都意识到了危险，它们就不太可能重复这种警告了。
“黑猩猩很重视别的成员发过来的信息。” 苏格兰圣安德鲁斯大学的研究员凯瑟琳？克罗克福德博士说道。“它们自愿给那些处在危险中但是豪不知情的组员发出警报信号，而不太可能给那些已经知道危险的人发出警报。”
克罗克福德博士说：“当个人开始因为通知别人和让他们知道情况而发出声音时，就意味着到了演变过程的关键阶段。”
这项研究提出了更多黑猩猩启动复杂通信所需的因素，它们在黑猩猩身上表现得非常明显，也比以前科学家疑似的要多。
克罗克福德博士补充说：“野生黑猩猩解决这些问题的优势是，在一个生态相关的背景里，它们只是简单地做一件它们一直都在做的事情，并且这些事情都是相关的。”（生物谷Bioon.com）
doi:10.1016/j.cub.2011.11.053
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Wild Chimpanzees Inform Ignorant Group Members of Danger
Catherine Crockford, Roman M. Wittig, Roger Mundry, Klaus Zuberbühler
The ability to recognize other individuals' mental states—their knowledge and beliefs, for example—is a fundamental part of human cognition and may be unique to our species. Tests of a “theory of mind” in animals have yielded conflicting results and . Some nonhuman primates can read others' intentions and know what others see, but they may not understand that, in others, perception can lead to knowledge and. Using an alarm-call-based field experiment, we show that chimpanzees were more likely to alarm call in response to a snake in the presence of unaware group members than in the presence of aware group members, suggesting that they recognize knowledge and ignorance in others. We monitored the behavior of 33 individuals to a model viper placed on their projected travel path. Alarm calls were significantly more common if the caller was with group members who had either not seen the snake or had not been present when alarm calls were emitted. Other factors, such as own arousal, perceived risk, or risk to receivers, did not significantly explain the likelihood of calling, although they did affect the call rates. Our results suggest that chimpanzees monitor the information available to other chimpanzees and control vocal production to selectively inform them.
