导读：一位研究者观察发现，棕熊会寻找合适的石头来给自己抓痒，并且会调整石头的位置来达到最佳的效果。这种行为此前只在人类和灵长类中有发现。
棕熊用布满藤壶的石头给自己蹭痒（图：Volker Deecke）
由于棕熊的生活非常隐秘，更不用说其危险性了，所以人们对其大脑的能力所知并不多。这实际上相当奇怪，因为在所有的食肉动物中，以熊的体型来说它们的大脑是最大的，并被认为是相当的聪明（尽管多数是些轶事传闻）。现在，一则新闻报道称，英国坎布里亚大学的研究者Volker Deecke在度假时无意中发现一头棕熊用一块布满藤壶的石头来帮自己减轻由于褪毛引起的瘙痒。Deecke将该景象拍了下来并发表在Animal Cognition杂志上。
人们常常会发现多种熊会靠在树上或石头上蹭痒，以此来缓和在夏天换下冬天所长的厚厚的毛时带来的瘙痒。不过人们从来就没有发现过，熊会自己捡起一块石头当做工具来给自己搔痒。实际上，这是人们观察到的四起非灵长类动物使用工具中的一起。大象通常会使用树枝来驱赶苍蝇，海豚也曾被发现用海绵来隐藏自己的嘴巴，一些鲸鱼会使用气泡来捕鱼。使用一块特异挑选的石头来完成某个任务，很显然是更高等智商的表现。
Deecke是研究鲸鱼的专家，在冰川湾海滨观察一对棕熊吃一头鲸的残骸的时候发现，其中一头棕熊开始在水底搜寻着什么东西。片刻后，棕熊签到水底并抓起一块石头（上面可清晰的看到布满了藤壶）并开始在自己的脸上和脖子上摩擦。这看起来并不是任何的石头都合棕熊的意，似乎只有上面布满了藤壶的石头用来蹭痒的效果更好。这也不仅仅是一次碰巧的事情。不多一会，该头棕熊扔掉了石头开始转悠，不多一会又开始寻找到另一块石头。棕熊一共重复这样的事情做了三次，每次都找到不同的石头，上面均布满了藤壶，用来摩擦它发痒的兽皮。Deecke还发现，棕熊在开始用石头蹭痒之前先在掌中对石头进行调整移到最佳的位置从而使蹭痒效果更好。这类行为此前只在人类和其他灵长类动物中出现。
Deecke认为，应该对熊开展更多的研究，因为很明显它们比人们所认识到的更能干。
Tool-use in the brown bear (Ursus arctos)
Volker B. Deecke
This is the first report of tool-using behaviour in a wild brown bear (Ursus arctos). Whereas the use of tools is comparatively common among primates and has also been documented in several species of birds, fishes and invertebrates, tool-using behaviours have so far been observed in only four species of non-primate mammal. The observation was made and photographed while studying the behaviour of a subadult brown bear in south-eastern Alaska. The animal repeatedly picked up barnacle-encrusted rocks in shallow water, manipulated and re-oriented them in its forepaws, and used them to rub its neck and muzzle. The behaviour probably served to relieve irritated skin or to remove food-remains from the fur. Bears habitually rub against stationary objects and overturn rocks and boulders during foraging and such rubbing behaviour could have been transferred to a freely movable object to classify as tool-use. The bear exhibited considerable motor skills when manipulating the rocks, which clearly shows that these animals possess the advanced motor learning necessary for tool-use. Advanced spatial cognition and motor skills for object manipulation during feeding and tool-use provide a possible explanation for why bears have the largest brains relative to body size of all carnivores. Systematic research into the cognitive abilities of bears, both in captivity and in the wild, is clearly warranted to fully understand their motor-learning skills and physical intelligence related to tool-use and other object manipulation tasks.
文献链接：https://www.springerlink.com/content/amj52437j51l2501/
