几个世纪以来，人类是如何改变狗的大脑结构的

几个世纪以来，人类是如何改变狗的大脑结构的

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.

狗是一群奇怪的动物。它们的体型从纽芬兰等熊市庞然大物到米莉(milly)等弱小动物不等。米莉是一只吉娃娃，身高不足4英寸，拥有世界最矮狗吉尼斯纪录。

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.

有些品种跑得很快。其他人则是跳高运动员、游泳运动员或挖掘者。警犬擅长嗅探，而灰狗主要靠视觉捕猎。博德牧羊犬擅长放牧，杰克罗素梗擅长从洞穴里冲狐狸。

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年的时间里，特别是自维多利亚时代的狗的创造热潮以来，人类的选择性繁殖已经产生了一个单一物种，它的身体变异比动物王国里几乎任何其他物种都要多。

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.

现在，科学家们已经提供了第一个证据，证明所有这些选择性的调整不仅改变了狗的大小、形状、颜色和行为，还改变了它们大脑的构造方式。

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.

他们的研究发表在周一的《神经科学杂志》(journal of neuroscience)上，首先对62只狗进行核磁共振扫描，这些狗曾到佐治亚大学兽医教学医院进行神经系统评估。所有的狗，代表33个品种，出院时大脑健康状况良好。但他们的扫描为科学家们提供了大量的数据。

"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.

“我们想问的第一个问题是，不同品种狗的大脑是否不同?”哈佛大学研究狗认知的神经科学家、该研究的主要作者艾琳·赫赫特说。

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.

事实上，从达克斯猎犬到杜宾猎犬，即使考虑到狗的整体大小和形状等因素，科学家们还是发现了狗的大脑之间有着明确的区别。

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.

通过观察不同品种的狗狗大脑中变化最大的区域，科学家们能够绘制出6个神经网络的地图，这些神经网络与某些功能有关，比如嗅觉或运动。研究小组发现，正如美国养犬俱乐部所描述的那样，这些网络的形状与每个品种的共同特征“显著相关”。

"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."

赫克特说：“不同犬种的大脑解剖结构各不相同，看来至少有些变异是由于对狩猎、放牧和看护等特定行为的选择性繁殖造成的。”

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.

换言之，犬脑的形状和大小不仅因品种而异，而且其内部结构也不同。这一发现有助于解释是什么让马耳他人表现得像马耳他人，还是让拳击手表现得像拳击手。

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.

林肯内布拉斯加州大学犬类认知与人类互动实验室主任杰弗里·史蒂文斯(jeffrey stevens)称，这项研究利用现有的核磁共振数据是“聪明的”，其前提是“令人兴奋的”。不过，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."

史蒂文斯说：“我认为，在文献和人们的观点中，有一点不一致，那就是将行为与繁殖联系起来有多有用。”在一个品种中，个体之间往往有很多变异。”

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.

史蒂文斯还指出，由于这些狗正在执行特定品种的任务，因此没有进行核磁共振扫描，因此很难得出将品种与行为联系起来的重大结论。

"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.

史蒂文斯说：“这在人类神经影像学领域是非常有名的，在这个领域，你要非常小心地做出任何基于大脑活动的认知过程的推论，而不是直接测试。”

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

但这又提出了另一个有趣的问题。今天的大多数狗并没有积极地扮演他们的品种创造的角色。

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.

事实上，所有63只研究犬都是家庭宠物，而不是工作犬。因此，尽管他们可能是伟大牧民或猎人的后代，但他们可能不会以任何严肃的身份执行这些任务。这可能会有很大的不同。

"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."

赫克特说：“这不像(你的大脑)每次学东西都会有新的皱纹。”但有很多研究表明，当你学习一门新语言或学习一项新的运动技能时，你的大脑会发生变化。”

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，一只拉布拉多猎犬做这类工作的目的，是为了取回被猎人射杀的鸟，它的大脑可能与实验室取回粘在沙发垫子之间的爆米花不同。

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.

史蒂文斯说，他认为这暗示着研究人员可能在做一些事情。他说，如果他们在宠物身上发现了如此显著的变异，想象一下工作犬的大脑中可能会发现什么。

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

史蒂文斯说：“如果你使用那些仍然是为了这些目的而饲养的动物，这种相关性实际上可能会更强。”

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.

亚利桑那大学犬类认知中心的博士生丹尼尔·霍施勒(DanielHorschler)说，在不同品种的狗身上发现的变异，可能被证明是理解大脑如何工作的一个重要模型。