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What Makes Dogs Such Great Sniffers?是什么让狗狗拥有极好的嗅觉呢？

Watch a dog greeting the world with its nose, or following invisible trails of scent¹, and you might wonder what you’re missing. In one study, dogs were able to smell a particular test scent a thousand times better than humans! What makes dogs such stupendous sniffers?
当看到一条狗用鼻子问候，或它正追寻着无形的味道时，或许想自己是不是丢了什么东西。一项研究发现，在闻某种特殊的气味时，狗的嗅觉要比人类强上千倍。到底是什么使得狗成为惊人的嗅探器呢？

Smell Receptors
嗅觉接受器

Like humans, dogs have special smell receptor cells lining² their noses. But dogs have about 20 times more of these cells than we do–and the differences don’t stop there!
像人类一样，狗在鼻子旁边有着特别的嗅觉接受器细胞。但狗拥有的嗅觉细胞是我们人类的20多倍，且差别不止这些。

From the receptor cells, information about smell travels along nerves to the olfactory³ bulbs, the parts of the brain where information about smell is processed. Relative to the size of its brain, a dog’s olfactory bulbs are much bigger than most other animals. If the animal kingdom held a sniffing⁴ Olympics, dogs and rats would probably battle for the gold, leaving the rest of us in the dust.
嗅觉信息从这些接收器细胞沿着神经被运输到嗅球，大脑中关于气味的信息在此处理。与动物的大脑尺寸相关，狗的嗅球比大多数其他动物要大的多。如果动物王国举行一场嗅觉奥林匹克赛的话，狗和老鼠很可能为冠军而战，其它动物就望尘莫及了。

Tongue Transportation
舌头传输

Another advantage dogs have is that the schnoz isn’t the only tool they use for smelling. When a dog licks your hand, or something less savory⁵ found in the street, its tongue transports molecules⁶ from that surface into its mouth. Just above the roof of the dog’s mouth is the vomeronasal organ, which gathers information on smell from the molecules the tongue delivers. Humans have vomeronasal organs, too, but compared to dogs, ours are very rudimentary.
狗的优势不仅在于它的鼻子。当一条狗添你的手，或添地上的一些不怎么好吃的东西时，它的舌头将水分子传输到它的嘴里。在狗嘴正上方的犁鼻器可用来收集关于舌头传过来的水分子的气味。人类也有犁鼻器，但与狗相比，我们的还处于初级阶段。

Although all dogs are stupendous sniffers, dogs bred for tracking such as beagles and bloodhounds are true professionals. There are also variations in individual dogs’ talents, and the dog’s diet and the type of scent all affect how well a dog can smell.
尽管所有的狗都是极好的嗅探器,在狗跟踪方面，如米格鲁猎犬和警犬是真正的专业人士。不同的狗也有不同的才能，狗的饮食和气味的类型会影响狗的嗅觉。