You may have recently seen a video from the Beijing Wildlife Zoo going viral. What exactly was so interesting about this video？ It shows a dog playing with big cats four to five times its size！ Many people might wonder if this dog has a death wish， but it seems that the dog and the big cats are good friends.

The dog was actually raised alongside the lion and tiger cubs， making up an odd but loving family， according to zoo officials. If you think this is a bit too wild， just remember that cross-species friendship has been common for centuries. People have domesticated many animals， most notably cats and dogs， and formed bonds with them as pets. Perhaps you even have a pet yourself.

There are many other instances of crossspecies friendships in captivity.

At an animal sanctuary in Santiago， Chile， a kitten named Marina and a piglet named Laura formed a friendship after they both came to the park. As neither animal had a mother， sanctuary staff said they instantly bonded when they met. Laura had been rescued from a slaughterhouse while Marina had been rescued from the street.

One possible explanation for these friendships is the environment of the zoo. Animals don’t hunt for their food and don’t need to worry about marking their territory or looking for mates in the way an animal in the wild would.“All those activities take time and energy， and if these needs are removed， the animals get bored，”Gordon Burghardt， a psychologist at The University Of Tenessee， US， told The Atlantic magazine.“In this particular situation， the animal’s motivation to engage socially and playfully may be higher in its need hierarchy than eating.”

Marc Bekoff， former biology professor at the University of Colorado， US， told Slate magazine，“I think the choices animals make in cross- species relationships are the same as they’d make in same- species relationships. Some dogs don’t like every other dog. Animals are very selective about the other individuals who they let into their lives.”

你最近或許看到過一段北京野生動(dòng)物園的視頻在網(wǎng)絡(luò)上爆紅。這個(gè)視頻究竟有趣在哪里？視頻中，一條狗在和相當(dāng)于它體型四、五倍大小的大型貓科動(dòng)物玩耍！很多人可能會(huì)想，狗是不是在找死，但這條狗似乎和“大貓們”是好朋友。

據(jù)動(dòng)物園工作人員介紹，這條狗實(shí)際上是和獅子、老虎幼崽一起養(yǎng)大的，于是它們組成了一個(gè)奇特又有愛的家庭。如果你覺得這有點(diǎn)太瘋狂了，請(qǐng)記住，跨物種的友誼已經(jīng)持續(xù)了幾個(gè)世紀(jì)。人類已經(jīng)馴養(yǎng)了許多動(dòng)物，最出名的便是貓和狗，人類將動(dòng)物當(dāng)作寵物，與其建立情感聯(lián)結(jié)。也許你自己都養(yǎng)著一只寵物呢。

圈養(yǎng)環(huán)境中，還有許多其它跨物種友誼的例子。

在智利圣地亞哥的一個(gè)動(dòng)物保護(hù)區(qū)，一只名叫瑪麗娜的小貓和一只名叫勞拉的小豬在來到園區(qū)后建立了友誼。保護(hù)區(qū)工作人員說，這兩只動(dòng)物都沒有母親，因此一見面就變得親密起來。勞拉是從屠宰場(chǎng)救出來的，而瑪麗娜是從街上救助的。

對(duì)于這些友誼，一個(gè)可能的解釋是動(dòng)物園的環(huán)境使然。動(dòng)物不需要捕獵食物，也不需要像野生動(dòng)物那樣擔(dān)心標(biāo)記領(lǐng)地或?qū)ふ遗渑??！八羞@些活動(dòng)都將耗費(fèi)時(shí)間和精力，如果動(dòng)物們不需要操心這些需求，就會(huì)感到無聊?！泵绹锛{西大學(xué)心理學(xué)家戈登·伯格哈特在接受《大西洋月刊》采訪時(shí)表示，“在這種特殊情況下，動(dòng)物們交朋友、玩耍的動(dòng)機(jī)就可能處于比進(jìn)食更高的需求層次?！?/p>

美國科羅拉多大學(xué)前生物學(xué)教授馬克·貝科夫在接受《頁巖》雜志采訪時(shí)表示：“我認(rèn)為動(dòng)物在跨物種關(guān)系中做出的選擇和在同物種關(guān)系中做出的選擇一樣。有些狗不喜歡其他的狗。動(dòng)物對(duì)進(jìn)入其生活的其他個(gè)體非常挑剔?！?/p>

（選自《21世紀(jì)學(xué)生英文報(bào)》）