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.

我們人類有學習、找出問題的原因并解決問題的能力。我們人類是有自知之明的，并且我們也存在意識，思想，對其他事物有感知。我們有語言并使用它去表達復雜的思想。所有的這些都是聰明的標志。科學家也許不同意聰明的最好、最完全的定義，但是他們通常贊成人類是聰明的。

在動物的王國里的其他成員也存在著聰明的標記，一些科學家也許會說動物以及人類的聰明的定義僅僅是一個程度上的問題，2005年當倫敦動物園展覽了”智人”圖片時被認識清除了。點擊上面的”下一個”箭頭了解其他的九種因為聰明而出眾的動物。

黑猩猩和我們十分相像

如果我們人類擁有智力，那么黑猩猩一定也有一些智慧：因為我們的染色體組98%以上是一樣的。黑猩猩制造并使用工具，有組織的打獵并且參加暴力行動。野生黑猩猩群體有獨特的行為和習慣。野外觀察和實驗室試驗表明，黑猩猩有移情、利他和自我意識的能力。在這個被描述的試驗中，黑猩猩在一系列的記憶力測試中表現好于人類。

海豚有創造力

這只澳大利亞的海豚當在海底覓食時用一個海綿保護她的嘴，這是從海豚媽媽傳給海豚女兒的一個使用工具的行為。科學家說這只是海豚聰明的標志之一。其他的標志包括獨特的口哨和敲擊也許會作為海豚的名字，也許在一種語言中使用。二十世紀60年的一個著名的試驗發現，一旦海豚領會到他們因為做出新奇的動作而被獎勵魚后，一對海豚因創造而激動興奮。當他們理解了這個意思時致使人類的測試項目失敗只是因減緩而嘆口氣。

大象存在自我意識

大象的大腦暗示大象一定知道世界上的一兩件事情。他們被認為可以安慰家族成員，在其他動物需要幫組時給予幫助，在水中玩耍，以及通過他們腳感覺的震動感來與同類交流。一些研究人員說，當一只叫“快樂”的亞洲母象在鏡子中認識自己時是一個最高的成就。復雜的行為僅與人類，黑猩猩和海豚共有。

頭足類動物有很大的大腦

章魚、魷魚以及烏賊有智力嗎？這是一個科學疑點，但是這些頭足類動物都是大海中的最聰明的無脊椎動物。頭足類動物的大腦圍繞著食道，但是和人類大腦一樣復雜，例如折疊的圓突和處理視覺和觸覺信息的獨特區域。頭足類動物有多聰明的辯論圍繞著譯碼觀察—這些生物有表面的抑制不住的好奇心、對厭倦蔑視、有學習的能力并且有使用工具的能力。章魚被認為有專門的肌肉控制進食。

烏鴉很狡猾

烏鴉是很狡猾的生物：他們將嫩枝、羽毛以及其他的小塊的碎片改造成工具在他們接觸不到的地方誘捕食物。一個叫貝蒂的烏鴉，將一根直的電線彎成鉤狀在一根管子里找回食物。烏鴉生來就是一個工具制造家，但是他們通過觀察老烏鴉學會手藝，這是一個烏鴉有較高的智力的標志。烏鴉的一種—­—大烏鴉，甚至顯示出利用他們的群居相互接觸的成果增加保護并獲得更多的食物。

松鼠是靠不住的

在這里描述的松鼠耍詭計？也許。最近研究人員報告說，嚙齒動物的像小偷一樣的貯藏行為詳細的表明了他們的欺騙性。在一個實驗室試驗中，松鼠觀察人類后偷人類花生這種行為增多了。盡管這一行為可能僅僅是一個學習行為的例子，研究人員稱這一發現為松鼠能解釋其他物種的意圖的一個標志。其他的研究表明嚙齒動物繪制三維地圖來記住他們儲存堅果的地點。并且在加利福尼亞松鼠將使自己的皮毛沾染響尾蛇的氣味來掩蓋自己本身的氣味以逃避天敵。

人類最好的朋友

狗是聰明的還是僅僅是擅長于基本的服從？例如他們能學會坐著，躺下和取物，但是他們能不能讀懂他們的主人的意圖？研究表明他們至少可以響應找食物的暗示，也就是理解的一種，科學家認為也許就像是人類理解某人的角度的觀點。在這個試驗中描述的狗準確的區分了狗的照片和風景的照片——這是一種狗能形成“狗”的概念的跡象。

貓的適應性

和一些狗的主人一樣，一些貓的主人曾經訓練他們的寵物坐下，打滾以及跳圈。貓學習通過觀察和模仿學習這些花招，正強化的被慫恿。但是訓練貓要比訓練狗難。這是不是意味著貓比狗笨?不盡然。貓的研究專家說貓科動物是不同的，他們是孤獨的動物，由生存的需求推動。這使得他們適應各種家庭馴養的環境甚至有蓬汽車至少9,500年。

豬既有智慧還愛干凈

這是有關豬的流言：據一些專家稱，豬也許是最聰明最干凈的已知的馴養動物。甚至與貓和狗相比。但是豬沒有汗腺，所以他們在污泥中打滾來保持涼爽。二十世紀九十年代的實驗證明豬很聰明。豬被訓練用他們的嘴移動電視屏幕上的指針，并用這個指針辨別他們認識的涂鴉和他們第一次見到的涂鴉。豬像黑猩猩一樣快速的完成了這個任務