Do Cats and Dogs Remember Their Past?貓狗記得過去嗎？

When I met my cat Pearlita， she lived in an alley between my apartment building and a gas station. She drank from puddles polluted by engine leaks and ate whatever she could find. Ten years later， with Pearlita curled up on my lap， making it hard to type， I can still remember how she wolfed down the food I put in the alley and how easy it was to lure her inside with more.

我是在公寓樓和加油站間的一條小巷里遇見我的愛貓小珍珠的。她喝那些因機油泄露而被污染的水坑里的水，能找到什么就吃什么。10年后，小珍珠蜷縮在我的大腿上，我幾乎無法敲字，但我仍記得她曾如何狼吞虎咽掉我放在巷子里的食物，我又曾怎樣輕易地用更多吃食將她誘入家門。

But does she remember her life on the streets？ And if so， which parts of it？

但她是否還記得自己在街邊流浪的生活？如果記得，記住的又是其中哪些過往？

This question has probably occurred to almost anyone with an animal friend， but for simplicity’s sake， we’ll limit this discussion to our feline and canine companions. Certainly they behave as though they have memories—after all， your special furball doesn’t treat you like a stranger each time you walk through the door—and evolutionary theory suggests as much： It behooves any long-lived animal to have long-lasting recollections. There have been rigorous scientific experiments， too， not enough to fully understand our dogs’ and cats’ memories， but enough to confirm their existence and to raise some interesting questions about how they compare to our own.

幾乎所有與動物為友的人都可能有過此類疑問，但簡單起見，我們這次的討論僅限于陪伴我們的貓和狗。當然，它們表現得就像是有記憶——畢竟，你的毛孩子不會在你每次進門時都當你是陌生人——而且進化理論也如此說明：任何長壽的動物都應當具備長期記憶。也有些嚴格的科學實驗，盡管還不足以讓我們完全了解狗和貓的記憶究竟是怎么回事，但也足以證實這種記憶是存在的，并讓人好奇貓狗的記憶與我們人類的記憶有何異同。

“It is tricky， because we can’t directly ask them，” says Mikel Delgado， an animal psychology researcher from the University of California， Davis who now dispenses advice on cat behavior with the company Feline Minds. “The way I think about it is： What’s important for animals to remember？”

“這很棘手，因為我們不能直接詢問它們?！奔又荽髮W戴維斯分校的動物心理學研究員邁克爾·德爾加多說，她現在為“貓科思維”公司提供關于貓行為的咨詢服務?！拔宜伎嫉姆较蚴牵簩游飩儊碚f，什么才是它們要記住的重要內容？”

For a cat or dog—or human—to remember events from way back， they must first be able to recall what happened just a few moments ago. To study this in controlled settings， scientists devise experiments in which animals are rewarded for correctly identifying objects they previously saw， asked to avoid obstacles without looking at them， or monitored while searching for food they saw being hidden. These methods don’t capture everything that cats and dogs can recall， of course; they’re intended to tease out the basics of their cognition.

對于貓狗甚或人類而言，要記住很久以前的事，必須首先能夠回憶起幾分鐘前剛發生的事。為了在受控環境下研究這一點，科學家們設計了一些實驗，內容是如果動物能正確識別它們之前看到的物體，就會得到獎勵；讓它們在不去看的前提下避開障礙物，或者觀察它們尋找曾被當面藏起來的食物。當然，這些方法無法涵蓋貓和狗所能回憶起的一切；實驗的目的是一窺它們認知的基本情況。

A few decades’ worth of data have shown that the species do indeed have short-term recall， and they convert certain events and interactions into long-term memories as they sleep and， crucially， dream. “Dreaming is often connected to the reorganization of memory，” says ádám Miklósi， an ethologist and canine cognition specialist at Hungary’s E?tv?s Loránd University. Both dogs and cats display the telltale neurological signatures of REM， short-wave sleep， and other patterns of snoozing that， in human and rat brains， are linked to the sorting of a day’s experiences.

數十年來的數據表明，貓狗確實有短期記憶，而且它們在睡覺時，尤其是做夢時，還會將某些事件和互動轉化為長期記憶。匈牙利厄特沃什·羅蘭大學的動物行為學者、犬類認知專家亞當·米克洛希說：“做夢通常與記憶的重組有關。”狗和貓都表現出快速眼動睡眠、短波睡眠和其他打盹類型的諸多神經特征；對人類和鼠類來說，這些神經特征意味著大腦在對一天的經歷進行整理。

One of the best-documented examples of long-term memories in dogs involves Chaser， a border collie famous for learning the names of more than 1，000 objects in three years. Impressive as that is， however， such semantic feats don’t necessarily mean that Chaser， who died in 2019 at the ripe old age of 15， could remember his puppyhood. That requires so-called episodic memories containing the details of an experience， the who-what-when-where.

關于狗的長期記憶，記錄最完善一例是一只名叫追獵者的邊境牧羊犬。它以在3年內學會了1000多種物體的名稱而聞名。追獵者在2019年時以15歲的高齡去世，盡管它在語義的記憶方面令人驚嘆，然而這并不一定意味著它能記起自己的童年。那需要所謂的情景記憶，其中包含每次經歷的諸多細節：人、事、時間和地點。

Until recently， scientists thought the canine mind was limited to associative memories： recollections of the relationships between experiences or events， but not the intricacies of the experiences and events themselves. Were that the case， then every time my dearly departed dog Comet climbed into our car the moment my parents started packing it， she wouldn’t have remembered the canoe rides， swims， and roasted marshmallows of past trips. Comet would simply have learned to identify the preparations with fun.

直到最近，科學家們還認為犬類的思維僅限于關聯記憶：能回憶起經歷之間或事件之間的關系，但無法記憶錯綜復雜的經歷和事件本身。如果是這樣的話，當我那已逝的愛犬彗星每每在我父母開始收拾行李時爬進車里，并不是因為她還記得過去旅行中的獨木舟漂流、游泳和烤棉花糖。她只是把準備工作和快樂聯系在了一起。

But in recent years， research conducted by Miklósi and his colleague Claudia Fugazza has shaken the idea that canines are restricted to such Pavlovian recall. In 2016 they confirmed， by way of an experiment in which they asked dogs to imitate actions modeled by a human minutes earlier， that the pooches did remember specific elements of what they’d experienced. In follow-up experiments， dogs repeated their own actions long after they first performed them， a finding that added an autobiographical layer to their episodic memories. Their thoughts didn’t just contain a jumble of disparate details， but were woven together by a sense of self.

但近年來，米克洛希和同事克勞迪婭·富加扎開展的研究動搖了“犬類只有巴甫洛夫式回憶”這一觀點。2016年，他們進行了一項實驗，讓狗模仿幾分鐘前人類示范的動作。實驗證明，狗的確能夠記住它們經歷中的特定元素。在后續實驗中，狗在第一次做出動作很久之后又重復了自己的動作，這一發現為它們的情景記憶增添了一層自我意識。它們的想法不僅僅包含雜亂而互不相干的細節，而是由一種自我意識編織而成的整體。

As for cats， tests of whether they returned to containers where they were previously fed lend scientific support to their version of episodic memory. “Cat memory is probably very much like dog memory，” says Miklósi.

至于貓，一些實驗測試過它們是否還會回到之前喂食的容器旁，以此為貓具有情景記憶提供了科學依據。米克洛希說：“貓的記憶可能跟狗的非常相似?！?/p>

Still， he and Delgado note that this kind of reminiscence might differ from our own. Humans can reflect on their memories in spontaneous， self-directed ways： I can think about the first concert I ever attended， a Pink Floyd show， without needing to see the ticket stub to remind me of it. How cats and dogs guide their own recall—if they need cues to trigger it or have a proclivity， like us， for wandering the halls of memory—is a mystery.

不過他和德爾加多也指出，此類記憶可能有別于我們人類的記憶。人類可以自發地、自我引導式地回想起自己的記憶。比如我不需要看到票根，就可以回憶起我看過的第一場演唱會，那是平克·弗洛伊德的一場演出。貓和狗如何控制自己的回憶——是需要線索觸發，還是像我們一樣喜歡在記憶的大廳中游蕩——還是一個謎。

It’s also less clear how our furry companions relive their distant memories. Mine play like a movie in my mind’s eye， which fits， as contemporary humans are a visually oriented species. But cats and dogs are far more reliant on other senses， especially smell. Could their recall come together as scents rather than images？ Two studies—of dogs in a dark room finding familiar objects with their noses， and of kittens recognizing their mothers by scent after years of separation—suggest as much. “Animals， I’m sure， are much more multisensory，” Delgado says. “Their memories might be scent or sound and not necessarily the images that we tend to picture when we’re replaying an episode in our minds.” I can still see my first encounter with Pearlita. Perhaps she can still smell it.

毛孩子們如何重溫遙遠的記憶亦尚未明晰。我的記憶像腦海中放的一部電影，這個比喻很合適，因為當代人類是視覺型的物種。但貓和狗會更依賴其他感官，尤其是嗅覺。它們的回憶會以氣味而非圖像的形式呈現嗎？兩項研究表明也許正是如此：一項是狗在黑暗的房間里用鼻子尋找熟悉的物品，另一項是小貓在分離多年后通過氣味認出母親。德爾加多說：“我確信動物依靠多種感官。它們的記憶主體可能是氣味或聲音，而不一定是人類在腦海中回放某個情節時往往會描繪出的圖像。”我仍然能“看”到我與小珍珠第一次相遇時的畫面。但也許對小珍珠來說，她還能“聞”到它。

Delgado also raises the question of language. In addition to being visually driven， human memories are structured by words and complex grammar， which some experts think is crucial to the power of recall. And while dogs and cats don’t have full-blown human-style language， they are able to communicate and represent meaning through sounds， postures， facial expressions， and other signals. Maybe memories formed without language are simply different， not weaker. They could even be more intense： less complex but undiluted by linguistic abstraction or， as Delgado points out， the second-guessing， what-if scenarios that humans tend to indulge in.

德爾加多還提出了語言的問題。人類記憶除了受視覺驅動之外，還由單詞和復雜的語法建構而成，一些專家認為這對回憶的能力至關重要。雖然狗和貓并沒有如同人類般成熟的語言，但它們能夠通過聲音、姿勢、面部表情和其他信號來進行交流、傳情達意。也許在沒有語言的前提下形成的記憶只是有些不同，但并非不清楚，甚至還更為強烈：沒那么復雜，但也不會受語言的抽象性影響，而且德爾加多指出，它也不會受揣測的影響。人類常常沉湎于思考假設情景，這就是揣測。

This and certain other questions about how cats and dogs perceive the past might prove impossible to illuminate scientifically and ethically. To empirically determine， for example， how adopted animals recall their people， we’d need to separate them from family for months—even years. “I’m okay with mystery，” Delgado says. “I’ve learned to live with the fact that there’s still so much we don’t know.” The details may be blurry， but it’s enough to know that our cats and dogs remember.

關于貓狗如何感知過往的各類問題，可能無法從科學和倫理的角度闡明。例如，要憑經驗確定被收養的動物如何回憶它們的原主人，我們需要將它們和原家庭分開數月甚至數年?！拔也唤橐膺@是個謎。”德爾加多說，“我學會了接受這樣一個事實，那就是仍然有很多事情是我們不知道的?！奔毠澘赡軙苣：?，但只要知曉我們的貓狗保有記憶就足夠了。

（譯者單位：對外經濟貿易大學）