It's the moment every dog owner instantly regrets ever letting their dog kiss them on the mouth: Watching that very same beloved, seemingly well-trained and civilized pup eagerly devour a stinky, steaming pile of poop off the sidewalk.

　　有一个时刻会让养狗的朋友后悔时常嘴对嘴亲狗——狗看似受过良好训练又有礼貌，但是也会吃下路边臭气熏天的热便便。

　　Ugh, gross! But why? Why?!

　　好恶心!但是狗为什么会吃便便呢?

　　It;s a topic that has long perplexed animal researchers and veterinarians. And if you Google the topic, you're likely to get more than a dozen different explanations ranging from canine anxiety to illness to simply boredom.

　　这个问题困扰动物研究学者和兽医们不止一时半刻。在网上搜搜看，能发现各种不同的解释，有的说因为犬类焦虑症，有的说因为生病，有的说狗只是太无聊了。

　　However, a new study led by veterinarian Benjamin Hart, director of the Center for Animal Behavior at the University of California at Davis, has managed to link the off-putting behavior to “greedy eating” (dogs that quickly ravish their food bowls, according to owners) as well as an instinct connected to canines’ ancestral wolf pack days.

　　但是加利福尼亚大学戴维斯分校区动物行为研究中心主任本杰明·哈特做了项调查，将狗这种倒胃口的行为归结为“贪吃”(养狗的人都说狗会迅速抢走饭碗)，也与犬类祖先狼的遗留本能有关。

　　As the Washington Post reports, Hart and his team surveyed over 3,000 dog owners. Of these subjects, 16 percent ate other dogs’ feces “frequently” (their owners had witnessed a crappy chow down session at least six times), and of those pups, 80 percent preferred fresh feces less than two days old. Well, who doesn’t?

　　《华盛顿邮报》报道，哈特和其团队对3000多位养狗人士进行了调查，16%的狗“常常”会吃其他狗的便便(狗主人至少见过六次这样的场景)，80%的狗更喜欢两天内的新鲜便便。谁不喜欢新鲜的食物呢?

　　Interestingly, the research suggested that the tendency towards coprophagia (the scientific term for poop-eating) was evident no matter a dog’s age, breed, diet, house-training status or compulsive behavior tendency. This finding has unleashed a new theory: Modern day dogs have inherited both their aversion to pooping where they live as well as their likelihood to eat fresh poop from their ancient wolf ancestors.

　　有趣的是，这项调查显示，年龄、品种、饮食习惯、训练水平、强制行为都不会干扰狗吃便便。这就带来了一个新的理论：如今的狗狗一边在遗传对便便的厌恶，一边又会像狼祖先一样吃新鲜的便便。

　　You see, wayyyy back in those wild days, wolves may’ve eaten the fresh feces of sick, lame or old members who accidentally let a load loose as a way to clean up inside and around their den. Since it takes about two days for parasites and other pathogens to develop, eating fresh poop is not usually dangerous, and in fact, eating poop that was festering in their living quarters was actually a helpful way to avoid intestinal parasites such as larvae and worms.

　　看到了吧，在很久很久很久以前，狼也会吃同类的粪便，不管对方是不是老弱病残，不管这坨便便的出现是不是为了清理狼窝。寄生虫和病原体要两天之后才会出现在粪便中，所以新鲜的粪便对食用者来说没什么危险。而且新鲜粪便会在狼的体内溃烂，能够有效避免幼虫和蠕虫寄生在肠道内。

　　That said, some great minds in the canine scientific community think there may be a bit more to it. For instance, Professor James Serpell of the University of Pennsylvania and editor of the recent book The Domestic Dog: Its Evolution, Behavior and Interactions with People, told theWashington Post he finds the wolf theory “plausible,” but he's also intrigued by the “greedy eaters” survey findings.

　　犬类研究圈认为好处不止于此。宾夕法尼亚大学教授詹姆斯·斯贝尔(James Serpell)，刚刚完成了新书《家犬：进化、行为和与人互动)》，他告诉《华盛顿邮报》，狼理论“有道理”，但是“贪吃”调查的结果也让他很感兴趣。

　　He referenced a study of free-roaming wild dogs in developing countries that scavenge for food and, as a result, fill up on a sizable amount of human feces. This seems to indicate that poop could be viewed, errr digested, as a second-hand food source.

　　他举例说，发展中国家的流浪狗在寻找食物时，也会吃掉相当多人类的便便。看起来好像便便是狗寻找食物的第二选择。

　　Today, dogs (and cats) “are fed diets that are relatively rich in fats and protein, not all of which may be completely digested, making their feces potentially attractive as a second hand food source,” Serpell told the Washington Post.

　　斯贝尔说，现在的狗(和猫)“都用富含脂肪和蛋白的食物喂养，但是这些食物不一定能全部消化，所以他们的便便就会成为诱狗的食物来源”。

　　So, there you have it. Poop-eating is probably a normal, evolutionary dog trait.

　　现在明白了吧，吃便便可能是狗正常进化中的特性。

　　But, take heart: Hart and his team are working on a solution. They’re currently looking at clinical trials of new methods and products that dissuade your pup from chomping down on their own or others’ droppings.

　　但是切记：哈特和团队一直在寻找解决方法，试图通过新方法和新产品的临床手段阻止宠物狗食用便便。

　　The best thing to do, for now, is keep your dog on a short leash and make sure to pick up your own lawn.

　　眼下最好的办法是给狗拴上短链，确保自家草坪里没有潜在第二食物源。