然而有一天，却有一些细微的骚动出现在本该一片沉寂的海面上。是一个细胞，一颗生命的种子，这让当时日复一日重复环境运动和四季变幻的地球，总算出现了一些新的生机。虽然它还很小、很脆弱，无法对环境产生一些比较明显的影响。但在漫长的时间里，它不断地分裂、繁殖，一部分长出根茎、枝叶，变成了植物，安静地呼吸着；而另一些则长出了腿、触角、尾巴之类的器官，在只有浅绿色的、结构简单的最初级植物的海洋中游荡。直到有一天，海洋已经被植物充塞，于是一些植物被迫向陆地扎根。一开始一切都很艰难，可一旦它们习惯了干燥和稀薄的空气，就变得比在海洋中漂浮更加健康茁壮。而那些初等的动物也不再将好奇心局限在海洋里，它们进化出了可以爬行的四肢，使陆地生活也能够变得得心应手，于是浮出了水面。地面生活虽然比海洋里日复一日的浪流涌动要有意思一些，但也有更多的危险与挑战。它们的四肢越发发达，躯体也不断向庞大进化，这就是我们耳熟能详的恐龙了。远古的爬行类里有许多庞然大物，尤其是食草类的动物，如鱼龙、斑龙和雷龙，长30-40英尺都是很正常的，它们的腿就像柱子一样粗壮。还有一些比较轻盈的爬行类，为了躲避肉食动物的爪牙，躲到树顶上，之后也一直在高处栖息，不轻易落到地面了。它们没有多少路需要走，只需要在这棵树和那棵树的枝头间跳来跳去，于是它们前肢的一部分进化得又宽又平，像降落伞一样，能够让他们在下落的时候更缓慢稳当，然后又经过了一段时间，它们的“降落伞”长出了羽毛，成了名副其实的翅膀，而这些就是最初的鸟类了。
读到这里，可能有读者会问，我们要讲的不是人类的起源吗，为什么讲了半天这些有的没的呢？要知道，我们必须对地球最初的环境有一个基础的认识，才能够理解人类到底为什么会在那种时间、那种状况下诞生。
那是一个属于恐龙的时代，然而突然有一天，这种曾经称霸过地球的生物却彻底灭绝了。科学家们至今无法确定其中的原因，可能是因为地球气候在短时间内发生了剧烈的变化，让它们无法存活，但最让人相信的说法是，在恐龙年代末期，地球遭到了小行星的撞击。美国科学家曾经在6500万年前的地层当中发现了高浓度的铱，超过正常含量几十倍甚至数百倍，其只可能在陨石中找到。他们还根据铱的含量，测算出那颗小行星的直径大约有十公里那么长。而那时候，正好是恐龙灭亡前的那段时间。让我们回到几千万年前如末日般的那天，这些爬行类动物仍然在地球上安逸漫步，狩猎，养育后代的时候，天空中突然闪现出一道刺眼的白光。一颗庞大的球体飞驰而来，摩擦大气层的火光几乎引燃了整片天空。它以每秒几十公里的速度笔直地撞进了大海，将海水破成两半，掀起巨大的海啸，还在海底撞出了一个极深的陨石坑。海水遇到高温迅速蒸发，刹那间，大气层就充满了滚烫的水汽。滔天的巨浪席卷而来，形成大洪水并淹没了陆地。洪水所过之处，万物凋敝，寸草不生，恐龙们无处可逃，于是死在水中，尸体也埋葬在湍流深处。小行星撞击还引起了德干高原强烈的火山喷发，使地球板块的运动方向发生了变化，甚至在之后的几年中，地球的大气层中仍然满是两颗行星撞击扬起的尘埃、蒸汽和火山灰，连阳光都无法穿透。地面上漆黑而冰冷，就算有大灾难当下的幸存者，也很难在后续的恶劣环境中存活下来，恐龙的时代就这么结束了。
而这之后，地球就是另一种生物的天下了。虽然爬行类可以说是它们的先祖，但它们彼此之间还是有诸多不同，比如它们身上作为爬行类象征的鳞片蜕去了，变成了覆盖全身的柔软毛发。而最大的区别表现在生育方式上，后者绝大多数都在体内孕育下一代，并以母乳哺育幼儿，而不是像爬行类一样将蛋下在外界，然后再进行孵化。那时候没有房屋，没有可以抵御外敌的坚厚墙壁，蛋以及刚出生的幼儿没有父母在身边细心地看护，是很容易被天敌作为食物掠走的。但父母又不可能不去寻找食物，永远守候在孩子们身边。哺乳动物的雌性怀孕时会将胎儿藏在自己肚子里，所以就可以少操心一些这方面的问题，孩子的出生率就会提高。它们还会一直把胎儿留在自己身边，直到它们学会狩猎的本领和在弱肉强食的丛林当中生存的法则，这样，它们独自开始自己人生的时候，往往已经能够独当一面了，就更容易生存下来。
其实原始的哺乳动物出现的比鸟类还要早几百万年，然而最初的时候，它们只是一些不起眼的小东西，而且数量十分稀少，在体格庞大、数量繁多的其他物种的映衬下，很容易就被忽视了。这些早期哺乳动物并不是偶然地、没有任何预兆地站到了自然界的顶峰，就像在它们之前曾经繁盛一时的那些食草、食肉的爬行动物一样，终有一天也会因为环境的更迭被拉下神坛。它们之间最根本的区别，其实是哺乳动物养育后代的方式，它们对后代的照顾堪称无微不至。几乎所有的爬行类动物在产卵之后都会对其不管不顾，任它自己孵化，一破壳就要独自应对危险的自然。孩子们与自己的父母毫无联系，甚至不知道它们是谁。同类之间也缺乏交流，不管是经验上的，还是信息上的。但哺乳动物则不同，在父母哺育后代的过程中，交流、模仿、教育都是存在的。一个生物并不仅仅是作为个体存在，还有血脉、族群之间的联系。可能有人会说，也有许多鱼类和爬行类也是成群结队地生活在一起啊，但是这种共同生活并没有任何社会性的羁绊，只是出于生存和繁殖的客观要求，如果不这样做，个体将很难生存。然而对哺乳动物来说，它们的共同生活是有实际的情感联系的，族群也具有某种社会性。
在诸多因素的作用下，虽然哺乳动物大脑的大小一开始跟别的生物并没有什么显著的区别，然而根据在地下发现的化石，在有迹可循的漫长岁月中，它们的脑容量普遍而稳定地处于一种增长的过程。
当时有一种哺乳动物生活在密林之中，长得有点像猴子或者猩猩，但又稍微有点不太一样。在猎食的过程中，它们的前肢渐渐灵活，并且进化出了像手一样的爪子；后肢也越发有力，直到能够仅凭两足站立，并且保持整个身体的平衡——这就是我们人类最早的祖先。
人类的祖先样貌丑陋，前额很低，下颌又非常突出，与现在的人类几乎看不出有什么共同点。他们身材比人类高大得多。最早他们衣不蔽体，而气候又总在严寒和酷暑之间循环，磨砺出了他们粗糙、褐色的皮肤。他们的全身都附着着又粗又长的毛发，四肢仍然是猿猴的样子，然而手指却要灵巧许多。
他们居住在密林之中，而且尚未学会使用火。他们也没有什么固定的食物——只要能吃，什么都吃，包括野草的根茎、树木的枝叶、果实、巢穴中的鸟蛋、易捕捉的小兽，全都是生吞进肚子。直到今天，战乱时代如果食物贫乏，人类饥不择食的远古天性仍然会复苏。
他们日出而作，四处寻找可以果腹的食物，等太阳落山，就找一个隐蔽的地方躲过危险的夜晚。因为夜晚降临，就会有许多嗜血的野兽会出来觅食，而人类并没有锐利的牙齿或是可以与之抗衡的工具，一旦被捉住，唯一的结局就是成为野兽齿下的亡魂。
但他们确实已经制造出了一些可以使用的简陋石器。人们曾经在欧洲发现过一些燧石和石块，被刻意削凿出锋利的边缘，可以起到锤子或刀的用途，但要跟猛兽搏斗就显得颇为不足了。根据发现它们的地层年龄，可以推算出那是在50万-100万年之前。后来，在海德堡，人们又挖到了一些别的原始石器，大约是二十五万年前那段时间入土的，比前面所说的那些要精细得多，还有一块巨大的下颚骨。科学家在研究之后得出结论，拥有这片下颚骨的生物是一种与人类长相相似的巨兽，躯干庞大，四肢粗壮，毛发浓密，但他们更倾向于认为这种生物只是一种与人类相近的种族。还有在苏塞克斯的皮尔当沉积层中，也曾经发现过与人类的头盖骨形状相似的巨大头骨，甚至比现存所有类人猿的头骨都要大。有一根象骨跟头骨被一起发现，它显然被精心加工过，磨成了圆棍的形状，还凿了一个小洞。这种生物也并非人类的先辈，而且跟海德堡所发现的生物不是一种。这说明在那些久远的时代，也许还有别的、有机会发展成高等智慧的生物存在，但到今天，就只剩下人类而已。
One day, however, there was a slight disturbance in what should have been a quiet sea. It was a cell, a seed of life, and it gave new life to a world where environmental movements and the seasons were repeated day in and day out. Although it is still very small and fragile, it can not have any more obvious impact on the environment. But over a long period of time, it continued to divide and multiply. Some grew roots, branches and leaves, and became plants, breathing quietly. Others grew legs, antennae, tails, and the like, roamed the seas with only the most primitive plants, light green and simple in structure. Until one day, the ocean was filled with plants, and some plants were forced to take root on land. It's tough at first, but once they get used to the dry, thin air, they're healthier and stronger than floating in the ocean. And the primitive animals no longer confined their curiosity to the sea. They evolved creeping limbs that made life on land so easy that they emerged. Life on the surface, while more interesting than the day-to-day currents of the ocean, is also more dangerous and challenging. With their more developed limbs and larger bodies, these are the dinosaurs we know so well. Ancient reptiles were full of giants, especially herbivores such as ichthyosaurs, Apatosaurus, and Brontosaurus. It was normal for them to be 30 to 40 feet long, with legs as strong as columns. Some of the lighter reptiles, in order to avoid the claws of predators, hide to the top of the tree, has also been high habitat, not easy to fall to the ground. They didn't have much to walk on, they just hopped between the branches of this tree and that tree, so part of their forelimbs evolved to be wide and flat, like parachutes, that allowed them to fall more slowly and steadily, and then after a while, their parachutes grew feathers and became wings, and these were the first birds. At this point, some readers may ask, aren't we talking about the origin of man, and why all this nonsense? You know, we have to have a basic understanding of the Earth's original environment in order to understand why human beings were born at that time and in that condition. It was the age of the dinosaurs, and then one day, the creature that once ruled the earth was wiped out. Scientists are still not sure why, perhaps because Earth's climate changed dramatically in a short period of time, making it impossible for them to survive, but the most plausible theory is that at the end of the age of dinosaurs, the earth was struck by an asteroid. US scientists have found high concentrations of iridium, tens or even hundreds of times higher than normal, in strata 65 million years old, and it can only be found in meteorites. Based on the Iridium content, they also determined that the asteroid was about 10 kilometers in diameter. And that was just before the dinosaurs died. Back on that fateful day ten million or three years ago, when the reptiles were still roaming the earth, hunting and raising their young, a bright white light flashed in the sky. A huge sphere hurtled toward us, its atmospheric friction nearly igniting the entire sky. It crashed straight into the ocean at tens of kilometers per second, breaking the water in half, creating a huge tsunami and creating an extremely deep crater at the bottom of the ocean. The water evaporates quickly in the heat, and in an instant, the atmosphere is filled with hot steam. Huge waves rolled in, creating a flood that flooded the land. Everywhere the flood went, everything withered and nothing grew. There was nowhere for the dinosaurs to escape. They died in the water, and their bodies were buried deep in the current. The asteroid impact also triggered a powerful volcanic eruption in Deccan Plateau, which changed the direction of the Earth's plates, even in the years that followed, the Earth's atmosphere is still full of dust, steam and volcanic ash from the impact of the two planets, which sunlight can not penetrate. The ground was dark and cold, and even if there were survivors of the current disaster, it would be difficult to survive the harsh conditions that followed, and the age of the dinosaurs was over. And after that, the Earth is the domain of another creature. Although reptiles can be said to be their ancestors, there are many differences between them, such as their reptilian symbol of the scale off, into a covered with soft hair. The biggest difference is in the way babies are born, most of which are born inside the body and breastfed rather than laid outside like reptiles before hatching. There were no houses, no thick walls to defend against enemies, and eggs and young children were easy prey for predators without their parents to watch over them. But parents can't stay with their children forever without searching for food. In mammals, when a female gets pregnant, she hides the fetus in her belly, so she can worry less about it and have more babies. They also keep their babies close to them until they learn how to hunt and how to survive in the jungle, so that they can begin their lives alone, when you're already on your own, you're more likely to survive. In fact, primitive mammals appeared one million or three years before birds, but at first they were small and insignificant, and very few in number, in contrast to other species, which are large and numerous, it is easy to overlook them. These early mammals did not rise to the top of the natural world by chance and without warning, like the herbivorous, carnivorous reptiles that flourished before them, will one day be brought down by the change of environment. The fundamental difference between them is the way mammals raise their young, and the care they provide for them. Almost all reptiles lay their eggs and then leave them to hatch, leaving them to fend for themselves as soon as they hatch. The children have no contact with their parents and do not even know who they are. There is also a lack of communication, both experiential and informational. But mammals are different, in the process of parents feeding their offspring, communication, imitation, education is there. A creature doesn't just exist as an individual, but as a bond between blood and race. It may be said that there are also many fish and reptiles that live together in groups, but this kind of living together does not have any social ties, only out of the objective requirements of survival and reproduction, if you don't do that, it's going to be very difficult for the individual to survive. For mammals, however, there is a real emotional connection to their shared existence, and a certain sociality to their group. For a number of reasons, although the size of a mammal's brain may not initially be significantly different from that of any other living creature, fossils found in the Earth's crust suggest that over a long period of time, their brain volumes are in a general and steady state of growth. There was a mammal that lived in the forest that looked a little bit like a monkey or an orangutan, but a little bit different. As they hunted, their forelimbs became flexible, and they developed hand like claws; their hind limbs became more powerful, until they were able to stand on only two feet, and maintain the balance of the whole body-this is our earliest human ancestors. Human ancestors were ugly, with low foreheads and prominent jaws, and had little in common with modern humans. They're much bigger than humans. At first they were naked, and the climate, which circulates between the cold and the heat, sharpened their rough, brown skin. They had thick, long hair all over their bodies, and their limbs were still ape-like, but their fingers were much more dexterous. They lived in a dense forest and had not yet learned to use fire. Nor did they have any fixed food -- anything they could eat, including the roots of weeds, the branches and leaves of trees, the fruit, the eggs in their nests, and the small, easy-to-catch beasts, all eaten raw. To this day, the ancient human instinct to eat whatever food is needed in times of war is still alive. They worked at sunrise, searching for food to eat, and when the sun went down, seeking shelter from the dangerous night. Because at night, there will be a lot of bloodthirsty beasts will come out to feed, and humans do not have sharp teeth or tools to fight against it, once caught, the only outcome is to become the beast under the teeth of the dead. But they did make some crude stone tools that could be used. Flints and stones have been found in Europe, with sharp edges cut out to serve as hammers or knives, but it is not enough to fight the beast. Based on the age of the strata in which they were found, we can estimate that it was between 500,000 and 1 million years ago. Later, in Heidelberg, other primitive stone tools were unearthed, some two hundred and fifty thond or so years ago, much more elaborate than those described above, and a large jawbone. The scientists concluded from their research that the creature with the jawbone was a human-like behemoth with a large trunk, thick limbs, and thick hair, but they are more likely to think of the creature as a human-like species. And in the sediments of Pure, Sussex, huge skulls similar in shape to human skulls have been found, even larger than those of all living great apes. An elephant bone was found along with the skull. It had apparently been carefully shaped into the shape of a round stick, with a small hole cut in it. This creature is not a descendant of man, and it is not a creature like the one found in Heidelberg. This means that in those distant times, there may have been other creatures that had the opportunity to develop into higher intelligence, but today, there are only humans left.
标题: 生命的源头
作者: 亚特伍德
字数: 3167
简介: 然而有一天，却有一些细微的骚动出现在本该一片沉寂的海面上。是一个细胞，一颗生命的种子，这让当时日复一日重复环境运动和四季变幻的地球，总算出现
