1　舞臺布景

我們生活在一個巨大問號的陰影之下。

我們是誰？

我們從哪里來？

我們到哪里去？

但是憑著百折不撓的勇氣，漸漸地，我們已經把這個問號朝遙遠的地平線推移，并期望在地平線之外找到答案。

我們并沒有走出多遠。

我們仍然知之甚少，但是已經到達一定階段，我們可以（比較精確地）推測許多事情。

我將在本章告訴你（根據我們現有的知識），人類剛出場時的舞臺是如何布置的。

In the beginning, the planet upon which we live was（as far as we now know）a large ball of flaming matter, a tiny cloud of smoke in the endless ocean of space. Gradually, in the course of millions of years, the surface burned itself out, and was covered with a thin layer of rocks.Upon these lifeless rocks the rain descended in endless torrents, wearing out the hard granite and carrying the dust to the valleys that lay hidden between the high cliffs of the steaming earth.

Finally the hour came when the sun broke through the clouds and saw how this little planet was covered with a few small puddles which were to develop into the mighty oceans of the eastern and western hemispheres.

Then one day the great wonder happened. What had been dead, gave birth to life.

The first living cell floated upon the waters of the sea.

For millions of years it drifted aimlessly with the currents. But during all that time it was developing certain habits that it might survive more easily upon the inhospitable earth. Some of these cells were happiest in the dark depths of the lakes and the pools. They took root in the limy sediments which had been carried down from the tops of the hills and they became

如果我們用一條這么長的線段，來表示動物在地球上生存的時間，那么這條細線也就表示了人類（或者一種與人類多少有些相似的生物）在地球上生存的時間。

人類是最后一個來到這個世界的動物，但他們很快開動腦筋，征服了自然力量。我們為何研究的是人類而不是貓、狗、馬或其他動物，就是出于這個原因。當然，這些動物身后也有著非常有趣的發展歷程。

起初，我們賴以生存的地球（據我們所知）是一團大火球，是浩瀚的宇宙之洋中的一縷云煙。經過了幾百萬年，它的表面漸漸燒光，并覆蓋了薄薄的巖石層。大雨不停地傾盆而下，沖刷著沒有生命的堅硬的花崗巖，并把砂石帶進山谷。那時地球上蒸汽騰騰，山谷掩藏在峻嶺之間。

終于，時機來了，太陽沖破云層，它看到這個小星球上有了幾處小水坑。后來，這些水坑發展成東西半球的大海洋。

就在這一天，奇跡出現了。死氣沉沉的環境中，產生了生命。

第一個生命細胞在海水中漂浮。

幾百萬年來，細胞都是毫無目的地隨波逐流。但是在那段時間，它養成了一些習慣，這使它能在環境惡劣的地球上更容易生存下來。有一些細胞喜歡生活在湖泊的黑暗深處。山頂的砂土被帶入湖中形成淤泥，這些細胞扎根于此，變成了植物。有些細胞則喜歡四處游走，還長出像蝎子一樣有關節的怪腿。它們沿著海底，在植物和看似水母的淺綠色的東西之間爬行。還有一些細胞長有鱗片，從一個地方游到另一個地方，尋找食物。它們漸漸在海洋中定居，海洋里到處都是數不清的魚類。

plants.Others preferred to move about and they grew strange jointed legs, like scorpions and began to crawl along the bottom of the sea amidst the plants and the pale green things that looked like jelly-fishes. Still others（covered with scales）depended upon a swimming motion to go from place to place in their search for food, and gradually they populated the ocean with myriads of fishes.

Meanwhile the plants had increased in number and they had to search for new dwelling places. There was no more room for them at the bottom of the sea.Reluctantly they left the water and made a new home in the marshes and on the mudbanks that lay at the foot of the mountains. Twice a day the tides of the ocean covered them with their brine. For the rest of the time, the plants made the best of their uncomfortable situation and tried to survive in the thin air which surrounded the surface of the planet. After centuries of training, they learned how to live as comfortably in the air as they had done in the water. They increased in size and became shrubs and trees and at last they learned how to grow lovely flowers which attracted the attention of the busy big bumble-bees and the birds who carried the seeds far and wide until the whole earth had become covered with green pastures, or lay dark under the shadow of the big trees.

But some of the fishes too had begun to leave the sea, and they had learned how to breathe with lungs as well as with gills. We call such creatures amphibious, which means that they are able to live with equal ease on the land and in the water. The first frog who crosses your path can tell you all about the pleasures of the double existence of the amphibian.

Once outside of the water, these animals gradually adapted themselves more and more to life on land. Some became reptiles（creatures who crawl like lizards）and they shared the silence of the forests with the insects. That they might move faster through

與此同時，植物也大量繁殖，不得不尋找新的居所。在海里，它們已經沒有更多的生存空間了。它們無可奈何地離開了水面，把新家安在山腳的沼澤地和泥灘上。海潮每天兩次用鹽水把它們澆灌。其余時間，植物努力讓自己適應惡劣的環境，以便在地表稀薄的空氣中生存。經過幾百年的訓練，它們學會了怎樣在空氣中生活得和水中一樣愜意。它們的體型不斷變大，長成灌木和樹。終于，它們學會了怎樣長成可愛的花朵，吸引忙碌的大黃蜂的注意，使之幫忙把種子撒播到遠處，直到遍地綠草茵茵，大樹成蔭。

有些魚類也開始離開大海，學會了用肺和鰓來呼吸。我們把這些生物稱為兩棲動物，它們在陸地生活得和在水中一樣舒適。從你眼前跳過的第一只青蛙會告訴你，兩棲動物的雙重生活方式妙不可言。

一旦離開水面，這些動物會讓自己越來越適應陸地的生活。有一些成為爬行動物（像蜥蜴一樣），與昆蟲一起分享著樹林的寧靜。為了在松軟的土地上更快穿行，它們的腿腳變得發達，身體變長。最后，世界上遍布了巨型怪獸（生物書中介紹的魚龍、斑龍和雷龍等）。它們有三四十英尺長，說得形象些，它們和大象在一

the soft soil, they improved upon their legs and their size increased until the world was populated with gigantic forms（which the hand-books of biology list under the names of Ichthyosaurus and Megalosaurus and Brontosaurus）who grew to be thirty to forty feet long and who could have played with elephants as a full grown cat plays with her kittens.

Some of the members of this reptilian family began to live in the tops of the trees, which were then often more than a hundred feet high. They no longer needed their legs for the purpose of walking, but it was necessary for them to move quickly from branch to branch. And so they changed a part of their skin into a sort of parachute, which stretched between the sides of their bodies and the small toes of their fore-feet, and gradually they covered this skinny parachute with feathers and made their tails into a steering gear and flew from tree to tree and developed into true birds.

Then a strange thing happened. All the gigantic reptiles dies within a short time. We do not know the reason. Perhaps it was due to a sudden change in climate. Perhaps they had grown so large that they could neither swim nor walk nor crawl, and they starved to death within sight but not within reach of the big ferns and trees. Whatever the cause, the million-year-old world-empire of the big reptiles was over.

The world now began to be occupied by very different creatures. They were the descendants of the reptiles but they were quite unlike these because they fed their young from the “mamm?” or the breasts of the mother. Wherefore modern science calls these animals “mammals.” They had shed the scales of the fish. They did not adopt the feathers of the bird, but they covered their bodies with hair. The mammals however developed other habits which gave their race a great advantage over the other animals. The female of the species carried the eggs of the young inside her body until they were hatched and while all

起就好比母貓逗仔貓。

后來，爬行動物家族的某些成員開始轉移到樹上生活。當時的樹一般都長到100多英尺高。這些動物不再需要用腿走路，但它們必須在樹枝間快速穿行。就這樣，它們將一部分皮膚變成降落傘，并在身體的兩側和前足的小指頭之間伸展開來。逐漸地，它們讓皮膚降落傘上長出羽毛，而尾部變成方向桿，在樹林里飛翔，最終進化為真正的鳥類。

接著發生了一件怪事。在很短的時間內，所有大型爬行動物都絕種了。我們不知其中緣由?；蛟S是因為氣候的突變?；蛟S是它們長得太大，既不能游泳，也走不快、爬不動，眼看著肥碩的蕨類植物和樹木卻夠不著，活活餓死了。不管是什么原因，總之由爬行動物統治了百萬年的王國就此結束了。

世界從此開始出現新的生物。它們是爬行動物的后代，卻與祖先大不相同，因為它們的母親用自己的乳房來哺育幼兒。為此，現代科學稱這些動物為“哺乳動物”。它們已經脫下魚鱗，還沒換上羽毛，不過身上長了毛發。可是，哺乳動物養成了另一些習性，使之優于其他動物。雌性哺乳動物在體內孕育幼崽，直到出生。然而，其他

other living beings, up to that time, had left their children exposed to the dangers of cold and heat, and the attacks of wild beasts, the mammals kept their young with them for a long time and sheltered them while they were still to weak to fight their enemies. In this way the young mammals were given a much better chance to survive, because they learned many things from their mothers, as you will know if you have ever watched a cat teaching her kittens to take care of themselves and how to wash their faces and how to catch mice.

But of these mammals I need not tell you much for you know them well. They surround you on all sides. They are your daily companions in the streets and in your home, and you can see your less familiar cousins behind the bars of the zoological garden.

And now we come to the parting of the ways when man suddenly leaves the endless procession of dumbly living and dying creatures and begins to use his reason to shape the destiny of his race.

One mammal in particular seemed to surpass all others in its ability to find food and shelter. It had learned to use its fore-feet for the purpose of holding its prey, and by dint of practice it had developed a hand-like claw. After innumerable attempts it had learned how to balance the whole of the body upon the hind legs.（This is a difficult act, which every child has to learn anew although the human race has been doing it for over a million years.）

This creature, half ape and half monkey but superior to both, became the most successful hunter and could make a living in every clime. For greater safety, it usually moved about in groups. It learned how to make strange grunts to warn its young of approaching danger and after many hundreds of thousands of years it began to use these throaty noises for the purpose of talking.

This creature, though you may hardly believe it, was your first “man-like” ancestor.

動物則把孩子暴露在危險的環境中，那里或冷或熱，或有野獸侵犯。哺乳動物會陪伴它的孩子很長一段時間，以便在孩子們弱小、不能御敵時進行保護。通過這種方式，年幼的哺乳動物存活的概率加大了，因為它們可以從母親那里學到許多本領。如果你觀察過母貓教幼貓如何照顧自己、怎樣洗臉、怎樣抓老鼠，你就會明白了。

對于這些哺乳動物，我不必多言，你太了解了。它們就在你的周圍，在大街上，在家中，它們是你每天的玩伴。在動物園的鐵欄里，你還能看見不太熟識的表親。

接著，我們來到一個岔路口，人類就是在這時離開了長長的隊伍，離開了百無聊賴的生活和生死難測的命運。從此，人類開始用自己的理性來把握種族的命運。

有一種哺乳動物，覓食和自保的能力似乎勝過其他動物。它已經學會用前腳抓住獵物，經過訓練，它的前腳變成像手一樣的爪。無數次的嘗試之后，它學會了如何用后腿支撐整個身體的平衡（這是一個高難度的動作，盡管百萬年來人類一直在做，可是每個孩子不得不從頭學起）。

這種動物，半猿半猴，卻又優于二者，是最杰出的獵手，可以在任何環境下生存。為了更加安全，它們常常集體行動。它們學會發出怪叫來警告孩子們遠離危險。幾十萬年后，它們開始用喉嚨發聲來進行交談。

也許你根本不信，但這種動物就是你的“類人”祖先。