We humans have the ability to learn, to reason and solve problems. We're self-aware, and we’re also conscious of the presence, thoughts and feelings of others. We make tools and practice the art of deception. We're creative. We think abstractly. We have language and use it to express complex ideas. All of these are arguably signs of intelligence. Scientists may not agree on the best and fullest definition of intelligence – but they generally agree that humans are highly intelligent.

Other members of the animal kingdom exhibit signs of intelligence as well, and some scientists might say the definition of animal vs. human intelligence is merely a matter of degree – a point that was brought home in 2005 when the London Zoo put “Homo sapiens” on display in the exhibit pictured here. Click the "Next" arrow above to learn about nine other species that stand out for their smarts.

Chimps are almost like us

If we humans possess intelligence, chimpanzees must have some as well: Our genomes are at least 98 percent identical. Chimps make and use tools, hunt in organized groups and engage in acts of violence. Wild troops have distinct behaviors and customs. Field observations and lab experiments show chimps are capable of empathy, altruism and self-awareness. In the experiment pictured here, chimps performed better than humans on a number memory test.

Dolphins get creative

This dolphin in Australia uses a sponge to protect her snout when foraging on the seafloor, a tool use behavior that is passed on from mother to daughter. Scientists say that’s just one sign of dolphin smarts. Other signs include distinct whistles and clicks that may serve as dolphin names, perhaps used in a type of language. A famous 1960s experiment found that a pair of dolphins entered a tizzy of creativity once they figured out their novel behaviors were rewarded with fish. Frustrated human test subjects just let out a sigh of relief when they caught on to the idea.

Elephants exhibit self-awareness

The sheer size of their brains suggests that elephants must know a thing or two about the ways of the world. They have been seen consoling family members, helping other species in times of need, playing in water and communicating with one another via vibrations sensed in their feet. A crowning achievement, some researchers say, was when this female Asian elephant named Happy recognized herself in the mirror. The complex behavior is shared only with humans, great apes and dolphins.

Cephalopods have big brains

Are octopi, squids and cuttlefish smart? That’s a matter of scientific intrigue, but such cephalopods are certainly among the brainiest invertebrates in the sea. The cephalopod brain surrounds the esophagus, but shares with the human brain features of complexity such as folded lobes and distinct regions for processing visual and tactile information. The how-smart debate swirls around deciphering observations that the creatures have a seemingly irrepressible curiosity, a disdain for boredom, an ability to learn and the capacity to use tools. The octopus pictured here exerts precise muscle control to eat.

Crows get crafty

Crows are crafty critters: They fashion tools from twigs, feathers and other bits of debris to snare food from hard-to-reach places. A crow named Betty, pictured here, uses a straight wire she bent into a hook to retrieve food from a tube. The birds are born with a tool-making ethic, but they hone their craft by watching their elders, a sign of higher intelligence. Ravens, a type of crow, have even been shown to manipulate the outcomes of their social interactions for added protection and more food.

Squirrels can be deceptive

Is the squirrel pictured here plotting deception? Perhaps. Researchers recently reported that the rodents put on elaborate shows of deceptive caching to thwart would-be thieves. The behavior increased in a lab experiment after squirrels observed humans stealing their peanuts. The researchers called the finding a sign that squirrels can interpret intentions of others, though it could just be a case of learned behavior. Other studies have shown the critters make three-dimensional maps to recall where they cache their nuts. And squirrels in California will cover their fur in the scent of rattlesnakes to mask their own scent from predators.

Man's best friend

Are dogs intelligent or just really good at basic obedience? They can learn to sit, lie down and fetch, for example, but can they read their owner's intentions? Research suggests they can at least find food in response to non-verbal cues, a type of understanding that scientists think may be akin to the human ability to understand someone else's point of view. The dog in the experiment pictured here accurately discriminated between photos of dogs and photos of landscapes – an indication the dog was able to form the concept of "dog."

Cats are adaptable

Like dog owners, some cat owners have trained their pets to sit down, roll over and jump through hoops. Cats learn the tricks by observation and imitation, egged on with positive reinforcement. But training cats is harder than dogs. Does that mean they are less intelligent? Not necessarily. Cat experts say felines are just different. They are solitary animals, motivated by the need to survive. This has allowed them to adapt to a variety of domestic environments for at least 9,500 years – even the hoods of cars.

Pigs are wise - and clean

Here's the dirt on pigs: They are perhaps the smartest, cleanest domestic animals known – more so than cats and dogs, according to some experts. But pigs don't have sweat glands, so they roll around in the mud to stay cool. A sign of their cleverness came from experiments in the 1990s. Pigs were trained to move a cursor on a video screen with their snouts and used the cursor to distinguish between scribbles they knew and those they were seeing for the first time. They learned the task as quickly as chimpanzees.

我们人类有学习、找出问题的原因并解决问题的能力。我们人类是有自知之明的，并且我们也存在意识，思想，对其他事物有感知。我们有语言并使用它去表达复杂的思想。所有的这些都是聪明的标志。科学家也许不同意聪明的最好、最完全的定义，但是他们通常赞成人类是聪明的。

在动物的王国里的其他成员也存在着聪明的标记，一些科学家也许会说动物以及人类的聪明的定义仅仅是一个程度上的问题，2005年当伦敦动物园展览了”智人”图片时被认识清除了。点击上面的”下一个”箭头了解其他的九种因为聪明而出众的动物。

黑猩猩和我们十分相像

如果我们人类拥有智力，那么黑猩猩一定也有一些智慧：因为我们的染色体组98%以上是一样的。黑猩猩制造并使用工具，有组织的打猎并且参加暴力行动。野生黑猩猩群体有独特的行为和习惯。野外观察和实验室试验表明，黑猩猩有移情、利他和自我意识的能力。在这个被描述的试验中，黑猩猩在一系列的记忆力测试中表现好于人类。

海豚有创造力

这只澳大利亚的海豚当在海底觅食时用一个海绵保护她的嘴，这是从海豚妈妈传给海豚女儿的一个使用工具的行为。科学家说这只是海豚聪明的标志之一。其他的标志包括独特的口哨和敲击也许会作为海豚的名字，也许在一种语言中使用。二十世纪60年的一个著名的试验发现，一旦海豚领会到他们因为做出新奇的动作而被奖励鱼后，一对海豚因创造而激动兴奋。当他们理解了这个意思时致使人类的测试项目失败只是因减缓而叹口气。

大象存在自我意识

大象的大脑暗示大象一定知道世界上的一两件事情。他们被认为可以安慰家族成员，在其他动物需要帮组时给予帮助，在水中玩耍，以及通过他们脚感觉的震动感来与同类交流。一些研究人员说，当一只叫“快乐”的亚洲母象在镜子中认识自己时是一个最高的成就。复杂的行为仅与人类，黑猩猩和海豚共有。

头足类动物有很大的大脑

章鱼、鱿鱼以及乌贼有智力吗？这是一个科学疑点，但是这些头足类动物都是大海中的最聪明的无脊椎动物。头足类动物的大脑围绕着食道，但是和人类大脑一样复杂，例如折叠的圆突和处理视觉和触觉信息的独特区域。头足类动物有多聪明的辩论围绕着译码观察—这些生物有表面的抑制不住的好奇心、对厌倦蔑视、有学习的能力并且有使用工具的能力。章鱼被认为有专门的肌肉控制进食。

乌鸦很狡猾

乌鸦是很狡猾的生物：他们将嫩枝、羽毛以及其他的小块的碎片改造成工具在他们接触不到的地方诱捕食物。一个叫贝蒂的乌鸦，将一根直的电线弯成钩状在一根管子里找回食物。乌鸦生来就是一个工具制造家，但是他们通过观察老乌鸦学会手艺，这是一个乌鸦有较高的智力的标志。乌鸦的一种——大乌鸦，甚至显示出利用他们的群居相互接触的成果增加保护并获得更多的食物。

松鼠是靠不住的

在这里描述的松鼠耍诡计？也许。最近研究人员报告说，啮齿动物的像小偷一样的贮藏行为详细的表明了他们的欺骗性。在一个实验室试验中，松鼠观察人类后偷人类花生这种行为增多了。尽管这一行为可能仅仅是一个学习行为的例子，研究人员称这一发现为松鼠能解释其他物种的意图的一个标志。其他的研究表明啮齿动物绘制三维地图来记住他们储存坚果的地点。并且在加利福尼亚松鼠将使自己的皮毛沾染响尾蛇的气味来掩盖自己本身的气味以逃避天敌。

人类最好的朋友

狗是聪明的还是仅仅是擅长于基本的服从？例如他们能学会坐着，躺下和取物，但是他们能不能读懂他们的主人的意图？研究表明他们至少可以响应找食物的暗示，也就是理解的一种，科学家认为也许就像是人类理解某人的角度的观点。在这个试验中描述的狗准确的区分了狗的照片和风景的照片——这是一种狗能形成“狗”的概念的迹象。

猫的适应性

和一些狗的主人一样，一些猫的主人曾经训练他们的宠物坐下，打滚以及跳圈。猫学习通过观察和模仿学习这些花招，正强化的被怂恿。但是训练猫要比训练狗难。这是不是意味着猫比狗笨?不尽然。猫的研究专家说猫科动物是不同的，他们是孤独的动物，由生存的需求推动。这使得他们适应各种家庭驯养的环境甚至有蓬汽车至少9,500年。

猪既有智慧还爱干净

这是有关猪的流言：据一些专家称，猪也许是最聪明最干净的已知的驯养动物。甚至与猫和狗相比。但是猪没有汗腺，所以他们在污泥中打滚来保持凉爽。二十世纪九十年代的实验证明猪很聪明。猪被训练用他们的嘴移动电视屏幕上的指针，并用这个指针辨别他们认识的涂鸦和他们第一次见到的涂鸦。猪像黑猩猩一样快速的完成了这个任务