貓狗之爭：從進化角度看貓科比犬科更好
It's the debate that has long divided animal lovers. Now scientists have confirmed that cats really are better than dogs – at least from an evolutionary perspective.
一直以來，“貓和狗哪個更好”這一問題將動物愛好者劃分爲兩大陣營。現在科學家已經證實貓確實比狗更好——至少從進化的角度來看是這樣。
A groundbreaking study of 2,000 ancient fossils reveals that felids – the cat family – have historically been much better at surviving than the "canid" dog clan, and often at the latter’s expense.
一項對2000個古代化石進行的開拓性研究揭示了從歷史上看，貓科動物家族的生存能力遠遠強於犬科動物家族，而且貓科動物的生存是以犬科動物的損耗爲代價的。
The research finds that cats have played a significant role in making 40 dog species extinct, outcompeting them for scarce food supplies because they are generally more effective hunters. But researchers found no evidence that dogs have wiped out a single cat species.
這項研究發現，貓科動物在40個犬科物種的滅絕過程中發揮了重要作用。由於貓科動物通常是更有效率的捕獵者，在奪取供應不足的食物的競爭中貓科動物勝過了犬科動物。但是研究人員沒有發現任何犬類動物消滅掉一個貓科物種的證據。
The dog family – which includes the wolves from which today’s domesticated dogs are descended – originated in North America about 40 million years ago and reached a maximum diversity around 20 million years later, when there were more than 30 species on the continent. At that point, the cat family arrived from Asia.
犬科家族——包括現在的馴養狗的祖先狼——起源於約4000萬年前的北美洲，在大約2000萬年後達到了物種多樣性的巔峯，當時在北美洲有超過30個犬類物種。與此同時，貓科動物也從亞洲來到此地。
"The arrival of cats to North America had a deadly impact on the diversity of the dog family. We usually expect changes in climate to play the overwhelming role in the evolution of species. Instead, competition among different carnivore species proved to be even more important for the dogs," said the report’s lead author, Dr Daniele Silvestro, of the University of Lausanne in Switzerland.
這項研究報告的第一作者、瑞士洛桑大學（University of Lausanne）的達妮埃爾·西爾韋斯特羅（Dr. Daniele Silvestro）博士表示：“貓科動物的到來給犬科動物的物種多樣性造成致命打擊。我們通常預計氣候變化會在物種進化過程中發揮最重要的作用。但對於犬科動物來說，不同食肉動物物種間的競爭被證明是更重要的。”
The influx of cats prompted a period of dramatic decline among the dog clan. This has left North America with just nine species of wild dog today, comprising different variations of wolves and foxes, according to the fossil analysis published in the journal PNAS.
貓科動物的涌入導致犬科動物數量在一段時間內大幅下降。依據這項發表在美國國家科學院院刊（PNAS）上的化石分析，這造成了如今北美洲僅存九個犬類物種，包括狼和狐狸的不同變種。
Dr Silvestro says it is unclear exactly why, when times were tough, the cats were able to see off dogs so comprehensively. But he believed it could be something to do with the retractable claws that ancient cats have passed down to their domesticated descendants, but which dogs don’t have.
西爾韋斯特羅博士稱，目前還不是十分清楚在當時的艱難歲月，貓科動物爲什麼能將犬科動物“驅逐”得那麼徹底。但是他認爲這可能跟古代貓科動物伸縮自如的爪子有關，這是犬科動物所不具有的。古代貓科動物還將這種爪子遺傳給了自己的後裔家貓。
Millions of years ago, some dog species, such as wolves, were effective killing machines, chasing down their prey at high speed and devouring it. All surviving dog species fall into this "runner" camp.
數百萬年前，某些犬科物種（比如說狼）是有效的殺戮機器，能以高速追捕獵物併吞食掉。所有幸存的犬科動物都屬於“奔跑系獵手”陣營。
But other dog species ambushed their prey in a manner similar to the cat family. However, these dogs weren’t as good as the cats at this technique – and all the canid species who used it are now extinct.
不過也有其他犬科動物伏擊獵物的方式與貓科動物相似。然而，這些犬類動物並不像貓科動物那樣擅長這項技能——所有曾使用這項技能的犬科動物現在都已經滅絕了。
Dr Silvestro explained: “The cats have retractable claws which they only pull out when they catch their prey. This means they don’t wear them out and they can keep them sharp. But the dogs can't do this, so they are at a disadvantage to the cats in an ambush situation.”
西爾韋斯特羅博士解釋稱：“貓科動物只有在抓到獵物時纔會亮出它們可伸縮的爪子，這意味着它們不會磨損並能夠時刻保持鋒利，但是犬科動物不能做到這一點。因此，同貓科動物相比，它們在伏擊方面處於劣勢。”
The evolutionary success of carnivorous animals is strongly linked to their ability to obtain food, meaning that there can be significant competition for prey when there is insufficient supply for the population.
食肉動物的進化成功在很大程度上與它們獲取食物的能力有關，這也意味着當食肉動物的食物供應不足時，獵物的爭奪將十分激烈。
"Felids must have been more efficient predators than most of the extinct species in the dog family," the report concluded.
該報告總結稱：“貓科動物與那些滅絕了的犬科動物相比一定是更有效的捕食者。”
Vocabulary
felid：貓科動物
canid：犬科動物
clan：家族
carnivore：食肉動物
influx：(人或物的)大量涌入
retractable：可縮回的，伸縮自如的
prey：獵物
ambush：伏擊
predator：捕食者
