Since their emergence over 200,000 years ago, modern humans have established homes and communities all over the planet. But they didn’t do it alone. Whatever corner of the globe you find homo sapiens in today, you’re likely to find another species nearby: Canis lupus familiaris. Whether they’re herding, hunting, sledding, or slouching the sheer variety of domestic dogs is staggering. But what makes the story of man’s best friend so surprising is that they all evolved from a creature often seen as one of our oldest rivals: Canis lupus, or the gray wolf.
自從二十多萬年前 現代人出現以來, 便在地球各地建立家園和社區。 但他們並非獨立完成。 現今,不論你在世界的 哪個角落發現了人類, 你很有可能也會在附近 發現另一種物種: 犬類。 牠們會畜牧、打獵、拉雪橇, 或無精打采地閒逛, 家犬的種類多到十分驚人。 但,身為人類最好的朋友, 狗的故事很讓人驚奇的是, 牠們都是從一種動物演化來的, 這種生物通常被認為 是我們最古老的對手: 灰狼。
When our Paleolithic ancestors first settled Eurasia roughly 100,000 years ago, wolves were one of their main rivals at the top of the food chain. Able to exert over 300 lbs. of pressure in one bone-crushing bite and sniff out prey more than a mile away, these formidable predators didn’t have much competition. Much like human hunter-gatherers, they lived and hunted in complex social groups consisting of a few nuclear families, and used their social skills to cooperatively take down larger creatures. Using these group tactics, they operated as effective persistence hunters, relying not on outrunning their prey, but pursuing it to the point of exhaustion.
約十萬年前,我們舊石器時代的 祖先最早在歐亞大陸定居, 那時,狼是他們 同在食物鏈頂端的主要對手。 狼的咬力超過三百磅, 足以咬碎骨頭, 且在一英哩以外就能聞到獵物, 沒有多少動物能與這種 令人畏懼的捕食者競爭。 很像人類的群獵者們, 牠們會組成複雜的 社會群體來生活和捕食, 群體由幾個核心家庭組成, 牠們會用群體的技能 來合作獵取更大的動物。 用這些團體戰略, 牠們像執著高效的獵人那樣運作, 仰賴的不是跑得比獵物快, 而是一直追趕獵物, 直到獵物累得跑不動爲止。
But when pitted against the similar strengths of their invasive new neighbors, wolves found themselves at a crossroads. For most packs, these bourgeoning bipeds represented a serious threat to their territory. But for some wolves, especially those without a pack, human camps offered new opportunities. Wolves that showed less aggression towards humans could come closer to their encampments, feeding on leftovers. And as these more docile scavengers outlasted their aggressive brethren, their genetic traits were passed on, gradually breeding tamer wolves in areas near human populations.
但,當與牠們實力相當的 侵略性新鄰居(人)較量時, 狼發現自己遇到重大的抉擇。 對大部分群體而言, 這些快速發展的兩足動物, 對牠們的領土是嚴重的威脅。 但,對某些狼而言, 特別是不跟群的狼, 人類的營地提供了新的機會。 對人類展現出較少侵略行為的狼, 可以比較接近人類的紮營處, 吃人類吃剩的食物。 當這些更溫順的撿剩食者 活得比其侵略性的同類更久時, 牠們的基因特質就會傳下去, 在人類族群附近的地區, 漸漸繁殖出更溫馴的狼。
Over time humans found a multitude of uses for these docile wolves. They helped to track and hunt prey, and might have served as sentinels to guard camps and warn of approaching enemies. Their similar social structure made it easy to integrate with human families and learn to understand their commands. Eventually they moved from the fringes of our communities into our homes, becoming humanity’s first domesticated animal.
隨時間推移,人類發現了 這些溫順的狼有許多用途。 牠們能協助追蹤和捕捉獵物, 還可以當衛兵來看守營地, 在有敵人靠近時發出警告。 牠們與人類類似的社會結構, 使其很容易和人類家庭融合, 並學習了解人類的指令。 最終,牠們從人類社區的邊緣, 搬進了人類的家中, 成為人類最早馴服的動物。
The earliest of these Proto-Dogs or Wolf-Dogs, seem to have appeared around 33,000 years ago, and would not have looked all that different from their wild cousins. They were primarily distinguished by their smaller size and a shorter snout full of comparatively smaller teeth. But as human cultures and occupations became more diverse and specialized, so did our friends. Short stocky dogs to herd livestock by nipping their heels; elongated dogs to flush badgers and foxes out of burrows; thin and sleek dogs for racing; and large, muscular dogs for guard duty. With the emergence of kennel clubs and dog shows during England’s Victorian era, these dog types were standardized into breeds, with many new ones bred purely for appearance. Sadly, while all dog breeds are the product of artificial selection, some are healthier than others. Many of these aesthetic characteristics come with congenital health problems, such as difficulty breathing or being prone to spinal injuries.
這些最早期的原始狗或狼狗 似乎是在三萬三千年前出現的, 在外觀上,和牠們的野外近親 看起來沒有太大的不同。 主要的區別方式 是牠們的體型較小, 鼻子較短,牙齒也相對較小。 但,隨著人類文化和職業 變得更多樣化和專門化, 我們的朋友也同樣改變了。 矮胖結實的狗會去咬 家畜的腳跟來協助畜牧; 長型的狗會把獾和狐狸 從藏身處趕出來; 又瘦又光滑的狗可以賽跑; 大型強壯的狗負責看守工作。 在英國維多利亞時期出現了 養狗俱樂部和狗展, 此時,狗的類型 被標準化為不同品種, 有許多新品種被繁殖出來, 單純是為了外觀。 不幸的是,雖然所有的狗類品種 都是人工選擇的產物, 有的品種卻比其他品種更健康。 許多美學上的特徵反而 會伴隨先天的健康問題, 比如呼吸困難,或脊椎容易受傷。
Humanity’s longest experiment in controlled evolution has had other side effects as well. Generations of selection for tameness have favored more juvenile and submissive traits that were pleasing to humans. This phenomenon of selecting traits associated with youth is known as neoteny, and can be seen in many domestic animals. Thousands of years of co-evolution may even have bonded us chemically. Not only can canines understand our emotions and body language, but when dogs and humans interact, both our bodies release oxytocin; a hormone commonly associated with feelings of love and protectiveness.
這項人類在控制演化上 所做的最長實驗, 它還帶來了其他副作用。 經過數世代針對溫馴來做篩選, 人類偏愛的活潑可愛和順從特質 被保留了下來。 這種篩選年幼有關特質的現象, 就是一般所知的「幼態持續」, 在許多家畜身上都可以看到。 數千年的共同演化,可能 也讓我們在化學上結合在一起。 犬科動物不僅能了解 我們的情緒和肢體語言, 且當狗和人互動時, 雙方的身體都會釋放出「催產素」; 這是一種荷爾蒙, 和愛及保護的感覺有關。
It might be difficult to fathom how every Pomeranian, Chihuahua, and Poodle are descended from fierce wolves. But the diversity of breeds today is the result of a relationship that precedes cities, agriculture, and even the disappearance of our Neanderthal cousins. And it’s heartening to know that given enough time, even our most dangerous rivals can become our fiercest friends.
很難推測出博美狗、 吉娃娃、貴賓狗怎麼會是 讓人畏懼的狼的後代。 但現今這麼多樣性的品種, 是一種關係產生的結果。 這種關係出現的時間 早於城市、農業, 甚至比我們的近親 穴居人的消失時間還早。 很令人振奮的一點是, 只要有足夠的時間, 即使是我們最危險的對手, 也有可能變成我們最兇猛的朋友。