Humans are especially good at solving problems using two tricks: language and tools. The manufacture and use of tools was once believed to be uniquely human, but we now know that we share this ability with some animal species, although it seems rare. The complexity of tool use is often seen as an indication of a species' intelligence.
There once was a story about a clever crow which lived in a laboratory. The crow was fed dried mash1), which needed to be moistened before the crow could eat it. However, the keepers occasionally forgot to do so. The crow found a solution to his keepers' absent-mindedness: he used a cup to get water to moisten the mash himself! The cup had been given to the crow as a toy but he used it to collect water from a trough2) on the other side of the room.
Hungry Egyptian vultures use ingenuity4) in obtaining their food. Since the shells of ostrich5) eggs are too hard to break open by simply pecking6) at them, the vultures use rocks to assist them. The vultures will search as far as 50 yards from the eggs in order to find a proper smashing7) tool.
Vultures originally threw the eggs to break them open. They then evolved to throwing rocks at the eggs. The use of rocks to break the eggs open probably began when a vulture accidentally hit an egg with a rock. Vultures' aim in stone-throwing is poor, hitting the target with only 40~60% of their throws. Despite their imperfect aim, the vultures persist until they succeed in cracking the egg.
When feeding, sea otters can often be seen floating on their backs. They dive to the bottom of the ocean and pick up a mollusk9) and a rock. Back at the surface, they then float on their backs placing the rock on their abdomens10). The otters then repeatedly hit the mollusk against the rock in order to break open the hard shell and gain access to the meat inside. Some otters keep the same stone throughout their entire lives, placing it inside their armpit11) for later use.
Indonesian octopuses use coconuts as protection from predators13). They carry the shells along with them—squatting14) their bodies inside, with their legs hanging over so they can walk along the ocean floor. When they get to a spot that looks like a nice place to camp, they cover themselves with the shells. They'd even pull the two halves together to create a ball that they can sit more safely inside.
The woodpecker finch, found in the Galapagos Islands, isn't actually a woodpecker. True woodpeckers peck to loosen bark on a tree, then use their long tongues to search for grubs16). Woodpecker finches' tongues are too short for that. So they use a cactus17) spine18) to pull grubs from the bark. The finches then drop the spine and hold it under their feet while eating the grub. The cactus spine is carried from branch to branch for reuse.
A researcher was fortunate enough to observe a young woodpecker finch's acquisition19) of the skill of using the cactus spine. The finch began by attempting to obtain grubs from a tree branch simply by using its beak20). When that system frequently failed, the finch snapped off a part of a forked twig in order to make a tool. Scientists also observed woodpecker finches shortening long cactus spines in order to form more manageable tools.
The green heron drops a small object onto the surface of the water. Fish swim to the surface, hoping that the object might be their food. The heron then seizes the fish and eats it.
The practice of bait22) fishing is rare among green herons. This fact indicates that it is not an innate behavior. The roots of using objects to attract fish are unclear. One theory suggests that herons are imitating human behavior when they use bait for fishing. Another possibility is that herons learn to use bait for fishing through experience, i.e. the heron accidentally drops an object in the water and sees the object's attraction to fish.
While manipulating poles in their play, chimps learned to use the poles to escape from their enclosure. Researchers observed that chimps were very selective about the poles which they used as climbing tools. They discarded old pieces of wood which might break, ones which were too long or too short for carrying. Chimps show sophisticated24) tool use in that they can modify25) objects to form tools. For example, they have been observed joining two sticks together to make a longer tool for reaching high places.
In Tanzania, chimps construct tools from grass and twigs which they use to extract ants from their holes. Wild chimps have also been observed using sticks to withdraw honey from beehives, dig up edible roots, and as levers26) to open boxes of bananas left by scientists. Leaves are also used as tools by chimps for collecting water and for wiping mud, blood, and sticky fruit from their bodies.
In an experiment, monkeys demonstrated similar to those of the chimps. These monkeys were faced with the challenge of extracting yogurt from narrow plastic tubes. The tubes were too narrow to probe with their fingers and were fixed to the table to prevent the monkeys from pouring out the contents. The monkeys cleverly made spoons from pieces of wood which were available in the experiment room.
1. mash [mAF] n. 麦麸(由谷糠和营养物质调成的混合物,用以饲养牲畜和家禽)
2. trough [trC:f] n. 饲料槽;饮水槽
3. vulture [5vQltFE(r)] n. 【鸟】兀鹫
4. ingenuity [7IndVI5nju:EtI] n. 心灵手巧;善于创造发明
5. ostrich [5CstrItF] n. 【鸟】鸵鸟
6. peck [pek] vi. 啄
7. smash [smAF] vt. 打碎,打破
8. sea otter: 海獭;otter [5CtE(r)] n.【动】水獭
9. mollusk [5mClEsk] n. <美> = mollusc【动】软体动物
10. abdomen [5AbdEmEn, Ab5dEumEn] n. 腹(部)
11. armpit [5B:mpIt] n. 腋(窝),夹肢窝
12. octopus [5CktEpEs] n. ([复] octopuses或octopi)【动】章鱼属软体动物;章鱼
13. predator [5predEtE(r)] n. 捕食者
14. squat [skwCt] vt. 使蹲,使蹲坐
15. woodpecker finch: 形树雀(“ ”即啄木鸟的意思);woodpecker [5wud7pekE(r)] n.【鸟】啄木鸟;finch [fIntF] n. 雀科鸣鸟(如燕雀、金翅雀等)
16. grub [^rQb] n.【昆】(昆虫的)幼虫
17. cactus [5kAktEs] n.【植】仙人掌;仙人掌属植物
18. spine [spaIn] n.【植】刺
19. acquisition [7AkwI5zIFEn] n. 取得,获得
20. beak [bi:k] n. (鹰、鹦鹉等的)喙
21. green heron: 【鸟】绿鹭;heron [5herEn] n.【鸟】鹭
22. bait [beIt] n. (诱捕鱼、兽等的)饵
23. chimp [tFImp] n. <口> = chimpanzee[7tFImpEn5zi:] n.【动】黑猩猩
24. sophisticated [sE5fIstIkeItId] adj. 老练的,富有经验的;精通的
25. modify [5mCdIfaI] vt. 更改;改变;改造
26. lever [5li:vE(r), 5levE(r)] n. 撬棒,杠杆