A Dog may be man's best friend. But man is not always a dog's. Over the centuries selective breeding has pulled at the canine body shape to produce what is often a grotesque distortion of the underlying wolf. Indeed, some of these distortions are, when found in people, regarded as pathologies.
Dog breeding does, though, offer a chance to those who would like to understand how body shape is controlled. The ancestry of pedigree pooches is well recorded, their generation time is short and their litter size reasonably large, so there is plenty of material to work with. Moreover, breeds are, by definition, inbred, and this simplifies genetic analysis. Those such as Elaine Ostrander, of America's National Human Genome Research Institute, who wish to identify the genetic basis of the features of particular pedigrees thus, have an ideal experimental animal.
狗可能是人類最好的朋友。但是人並不總是狗的。在過去的幾個世紀裡，選擇性繁殖一直在利用犬類的體型來製造一種通常是狼的怪異變形。事實上，當在人身上發現這些扭曲時，有些被視為病態。
然而，對於那些想要了解如何控制體型的人來說，養狗確實提供了一個機會。純種狗的祖先有很好的記錄，它們的繁殖時間很短，而且它們的產仔數量也相當大，所以有大量的材料可以研究。此外，根據定義，品種是近親繁殖的，這簡化了遺傳分析。美國國家人類基因組研究所的伊萊恩·奧斯特蘭德(Elaine Ostrander)等人希望確定特定血統特徵的遺傳基礎，因此擁有了一種理想的實驗動物。
1. excellent excessive selective selected2. diseases epidemics pathologies medications3. puppy little litter offspring4. Hence However Moreover So5. representative expected general ideal1. selective：缺形容詞，根據句意「幾個世紀以來，一些品種的狗從狼中選出來陪伴人類」。
2. pathologies：缺名詞，根據句意「如果這些變異發生在人類身上，就會被認為是一種病變」。pathologies, 表示病態.
3. litter：litter-size 表示產仔數量。
4. Moreover：缺副詞，前句提到狗的好處，後面也提到「簡化遺傳分析」也屬優勢，所以這裡表示遞進，選擇moreover。
5. ideal：缺形容詞，前文描述狗這種動物的好處，根據句意「擁有了一種理想的實驗動物」。
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