幾個世紀以來，人類是如何改變狗的大腦結(jié)構(gòu)的

幾個世紀以來，人類是如何改變狗的大腦結(jié)構(gòu)的

Dogs are a weird bunch. They range in size from bearish behemoths like Newfoundlands to pipsqueaks like Milly, a Chihuahua who measures less than four inches tall and holds the Guinness record for World's Shortest Dog.

狗是一群奇怪的動物。它們的體型從紐芬蘭等熊市龐然大物到米莉(milly)等弱小動物不等。米莉是一只吉娃娃，身高不足4英寸，擁有世界最矮狗吉尼斯紀錄。

Some breeds are fast runners. Others are jumpers, swimmers or diggers. Bloodhounds specialize in sniffing, while greyhounds hunt primarily by sight. Border collies excel at herding, Jack Russell terriers at flushing foxes from dens.

有些品種跑得很快。其他人則是跳高運動員、游泳運動員或挖掘者。警犬擅長嗅探，而灰狗主要靠視覺捕獵。博德牧羊犬擅長放牧，杰克羅素梗擅長從洞穴里沖狐貍。

Over at least 15,000 years, and especially since a Victorian-era dog-creation craze, selective breeding by humans has resulted in a single species with more physical variation than almost any other in the animal kingdom.

至少在15000年的時間里，特別是自維多利亞時代的狗的創(chuàng)造熱潮以來，人類的選擇性繁殖已經(jīng)產(chǎn)生了一個單一物種，它的身體變異比動物王國里幾乎任何其他物種都要多。

And now, scientists have provided the first evidence that all of this selective tweaking hasn't just changed dogs' sizes, shapes, colors and behaviors - it's also altered the way their brains are built.

現(xiàn)在，科學(xué)家們已經(jīng)提供了第一個證據(jù)，證明所有這些選擇性的調(diào)整不僅改變了狗的大小、形狀、顏色和行為，還改變了它們大腦的構(gòu)造方式。

Their research, published Monday in The Journal of Neuroscience, began with MRI scans from 62 dogs that had visited the University of Georgia Veterinary Teaching Hospital for neurological evaluations. All the dogs, representing 33 breeds, were discharged with clean bills of brain health. But their scans provided the scientists with a treasure trove of data.

他們的研究發(fā)表在周一的《神經(jīng)科學(xué)雜志》(journal of neuroscience)上，首先對62只狗進行核磁共振掃描，這些狗曾到佐治亞大學(xué)獸醫(yī)教學(xué)醫(yī)院進行神經(jīng)系統(tǒng)評估。所有的狗，代表33個品種，出院時大腦健康狀況良好。但他們的掃描為科學(xué)家們提供了大量的數(shù)據(jù)。

"The first question we wanted to ask was, are the brains of different breeds of dogs different?" said Erin Hecht, a neuroscientist studying dog cognition at Harvard University and lead author of the study.

“我們想問的第一個問題是，不同品種狗的大腦是否不同?”哈佛大學(xué)研究狗認知的神經(jīng)科學(xué)家、該研究的主要作者艾琳·赫赫特說。

Indeed, from Dachshunds to Dobermans, the scientists found well-defined differences between dog brains, even after accounting for things such as the pooches' overall size and shape.

事實上，從達克斯獵犬到杜賓獵犬，即使考慮到狗的整體大小和形狀等因素，科學(xué)家們還是發(fā)現(xiàn)了狗的大腦之間有著明確的區(qū)別。

By looking at the areas of the dogs' brains that varied most across the breeds, the scientists were able to create maps of six neural networks linked to certain functions, such as the sense of smell or movement. The team found the shape of these networks "correlated significantly" with common traits associated with each breed, as described by the American Kennel Club.

通過觀察不同品種的狗狗大腦中變化最大的區(qū)域，科學(xué)家們能夠繪制出6個神經(jīng)網(wǎng)絡(luò)的地圖，這些神經(jīng)網(wǎng)絡(luò)與某些功能有關(guān)，比如嗅覺或運動。研究小組發(fā)現(xiàn)，正如美國養(yǎng)犬俱樂部所描述的那樣，這些網(wǎng)絡(luò)的形狀與每個品種的共同特征“顯著相關(guān)”。

"Brain anatomy varies across dog breeds," Hecht said, "and it appears that at least some of this variation is due to selective breeding for particular behaviors like hunting, herding and guarding."

赫克特說：“不同犬種的大腦解剖結(jié)構(gòu)各不相同，看來至少有些變異是由于對狩獵、放牧和看護等特定行為的選擇性繁殖造成的。”

In other words, not only do the shapes and sizes of canine brains vary by breed, the structures within those brains also are different. This discovery helps explain what makes a Maltese act like a Maltese, or a boxer like a boxer.

換言之，犬腦的形狀和大小不僅因品種而異，而且其內(nèi)部結(jié)構(gòu)也不同。這一發(fā)現(xiàn)有助于解釋是什么讓馬耳他人表現(xiàn)得像馬耳他人，還是讓拳擊手表現(xiàn)得像拳擊手。

Jeffrey Stevens, director of the Canine Cognition and Human Interaction Lab at the University of Nebraska at Lincoln, called the study's use of existing MRI data "clever" and its premise "exciting." However, he offered some words of caution.

林肯內(nèi)布拉斯加州大學(xué)犬類認知與人類互動實驗室主任杰弗里·史蒂文斯(jeffrey stevens)稱，這項研究利用現(xiàn)有的核磁共振數(shù)據(jù)是“聰明的”，其前提是“令人興奮的”。不過，他也提出了一些警告。

"The one thing that I think there's a bit of disagreement on in the literature and in people's views is how useful it is to map behaviors to breeds," Stevens said. "There's often a lot of variation within a breed, across individuals."

史蒂文斯說：“我認為，在文獻和人們的觀點中，有一點不一致，那就是將行為與繁殖聯(lián)系起來有多有用。”在一個品種中，個體之間往往有很多變異。”

Stevens also noted the MRI scans weren't performed as the dogs were performing breed-specific tasks, making it difficult to draw big conclusions linking breed to behavior.

史蒂文斯還指出，由于這些狗正在執(zhí)行特定品種的任務(wù)，因此沒有進行核磁共振掃描，因此很難得出將品種與行為聯(lián)系起來的重大結(jié)論。

"This is very well known in the human neuroimaging field, where you want to be really careful drawing any inferences about cognitive processes that are based on brain activity that you're not directly testing," Stevens said.

史蒂文斯說：“這在人類神經(jīng)影像學(xué)領(lǐng)域是非常有名的，在這個領(lǐng)域，你要非常小心地做出任何基于大腦活動的認知過程的推論，而不是直接測試。”

But this raises another intriguing question. Most dogs today do not actively fill the roles for which their breed was created.

但這又提出了另一個有趣的問題。今天的大多數(shù)狗并沒有積極地扮演他們的品種創(chuàng)造的角色。

In fact, all 63 study dogs were house pets, not working dogs. So even though they may be the descendants of great herders or hunters, they probably don't perform those tasks in any serious capacity. That could make a big difference.

事實上，所有63只研究犬都是家庭寵物，而不是工作犬。因此，盡管他們可能是偉大牧民或獵人的后代，但他們可能不會以任何嚴肅的身份執(zhí)行這些任務(wù)。這可能會有很大的不同。

"It's not like [your brain] gets a new wrinkle every time you learn something," Hecht said. "But there have been lots of studies that show your brain changes as you learn a new language or as you learn a new motor skill."

赫克特說：“這不像(你的大腦)每次學(xué)東西都會有新的皺紋。”但有很多研究表明，當(dāng)你學(xué)習(xí)一門新語言或?qū)W習(xí)一項新的運動技能時，你的大腦會發(fā)生變化。”

So it's quite possible that a Labrador retriever that does the job its kind was bred to do - retrieving birds shot by hunters - might have a brain that looks different from a Lab that retrieves popcorn stuck between couch cushions.

所以很有可能，一只拉布拉多獵犬做這類工作的目的，是為了取回被獵人射殺的鳥，它的大腦可能與實驗室取回粘在沙發(fā)墊子之間的爆米花不同。

Stevens said he viewed this as a hint that the researchers might be onto something. If they've managed to find such significant variation in pets, he said, imagine what might be discovered in the brains of working dogs.

史蒂文斯說，他認為這暗示著研究人員可能在做一些事情。他說，如果他們在寵物身上發(fā)現(xiàn)了如此顯著的變異，想象一下工作犬的大腦中可能會發(fā)現(xiàn)什么。

"The correlations actually could be stronger if you used animals that were still bred for those purposes," Stevens said.

史蒂文斯說：“如果你使用那些仍然是為了這些目的而飼養(yǎng)的動物，這種相關(guān)性實際上可能會更強。”

Daniel Horschler, a PhD student at the University of Arizona's Canine Cognition Center, said the variation found across dog breeds could prove to be an important model for understanding how brains work in general.

亞利桑那大學(xué)犬類認知中心的博士生丹尼爾·霍施勒(DanielHorschler)說，在不同品種的狗身上發(fā)現(xiàn)的變異，可能被證明是理解大腦如何工作的一個重要模型。