英文原文 Darwin
a ship sailing through life with a cargo of genes
Hilde was awakened on Sunday morning by a loud bump. It was the ring binder falling on the floor. She had been lying in bed reading about Sophie and Alber-to's conversation on Marx and had fallen asleep. The reading lamp by the bed had been on all night.
The green glowing digits on her desk alarm clock showed 8:59.
She had been dreaming about huge factories and polluted cities; a little girl sitting at a street corner selling matches--well-dressed people in long coats passing by without as much as a glance.
When Hilde sat up in bed she remembered the legislators who were to wake up in a society they themselves had created. Hilde was glad she had woken up in Bjer-kely, at any rate.
Would she have dared to wake up in Norway without knowing whereabouts in Norway she would wake up?
But it was not only a question of where she would wake up. Could she not just as easily have woken up in a different age? In the Middle Ages, for instance--or in the Stone Age ten or twenty thousand years ago? Hilde tried to imagine herself sitting at the entrance to a cave, scraping an animal hide, perhaps.
What could it have been like to be a fifteen-year-old girl before there was anything called a culture? How would she have thought? Could she have had thoughts at all?
Hilde pulled on a sweater, heaved the ring binder onto the bed and settled down to read the next chapter.
Alberto had just said "Next chapter!" when somebody knocked on the door of the major's cabin.
"We don't have any choice, do we?" said Sophie.
"No, I suppose we don't," said Alberto.
On the step outside stood a very old man with long white hair and a beard. He held a staff in one hand, and in the other a board on which was painted a picture of a boat The boat was crowded with all kinds of animals. "And who is this elderly gentleman?" asked Alberto.
"My name is Noah."
"I guessed as much."
"Your oldest ancestor, my son. But it is probably no longer fashionable to recognize one's ancestors."
"What is that in your hand?" asked Sophie.
"This is a picture of all the animals that were saved from the Flood. Here, my daughter, it is for you."
Sophie took the large board.
"Well, I'd better go home and tend the grapevines," the old man said, and giving a little jump, he clicked his heels together in the air and skipped merrily away into the woods in the manner peculiar to very old men now and then.
Sophie and Alberto went inside and sat down again. Sophie began to look at the picture, but before she had a chance to study it, Alberto took it from her with an authoritative grasp.
"We'll concentrate on the broad outlines first."
"Okay, okay."
"I forgot to mention that Marx lived the last 34 years of his life in London. He moved there in 1849 and died in 1883. All that time Charles Darwin was living just outside London. He died in 1882 and was buried with great pomp and ceremony in Westminster Abbey as one of England's distinguished sons. So Marx and Darwin's paths crossed, but not only in time and space. Marx wanted to dedicate the English edition of his greatest work, Capital, to Darwin, but Darwin declined the honor. When Marx died the year after Darwin, his friend Friedrich En-gels said: As Darwin discovered the theory of organic evolution, so Marx discovered the theory of mankind's historical evolution."
"I see."
"Another great thinker who was to link his work to Darwin was the psychologist Sigmund Freud. He also lived his last years in London. Freud said that both Darwin's theory of evolution and his own psychoanalysis had resulted in an affront to mankind's naive egoism."
"That was a lot of names at one time. Are we talking about Marx, Darwin, or Freud?"
"In a broader sense we can talk about a naturalistic current from the middle of the nineteenth century until quite far into our own. By 'naturalistic' we mean a sense of reality that accepts no other reality than nature and the sensory world. A naturalist therefore also considers mankind to be part of nature. A naturalistic scientist will exclusively rely on natural phenomena--not on either rationalistic suppositions or any form of divine revelation."
"And that applies to Marx, Darwin, and Freud?"
"Absolutely. The key words from the middle of the last century were nature, environment, history, evolution, and growth. Marx had pointed out that human ideologies were a product of the basis of society. Darwin showed that mankind was the result of a slow biological evolution, and Freud's studies of the unconscious revealed that people's actions were often the result of 'animal' urges or instincts."
"I think I understand more or less what you mean by naturalistic, but isn't it best we talk about one person at a time?"
"We'll talk about Darwin, Sophie. You may recall that the pre-Socratics looked for natural explanations of the processes of nature. In the same way that they had to distance themselves from ancient mythological explanations, Darwin had to distance himself from the church's view of the creation of man and beast."
"But was he a real philosopher?"
"Darwin was a biologist and a natural scientist. But he was also the scientist of recent times who has most openly challenged the Biblical view of man's place in Creation."
"So you'll have to say something about Darwin's theory of evolution."
"Let's begin with Darwin the man. He was born in the little town of Shrewsbury in 1809. His father, Dr. Robert Darwin, was a renowned local physician, and very strict about his son's upbringing. When Charles was a pupil at the local grammar school, his headmaster described him as a boy who was always flying around, fooling about with stuff and nonsense, and never doing a stroke of anything that was the slightest bit useful. By 'useful,' the headmaster meant cramming Greek and Latin verbs. By 'flying around,' he was referring among other things to the fact that Charles clambered around collecting beetles of all kinds."
"I'll bet he came to regret those words."
"When he subsequently studied theology, Charles was far more interested in bird-watching and collecting insects, so he did not get very good grades in theology. But while he was still at college, he gained himself a reputation as a natural scientist, not least due to his interest in geology, which was perhaps the most expansive science of the day. As soon as he had graduated in theology at Cam-bridge in April 1831, he went to North Wales to study rock formations and to search for fossils. In August of the same year, when he was barely twenty-two years old, he received a letter which was to determine the course of his whole life . . ."
"What was the letter about?"
"It was from his friend and teacher, John Steven Hens-low. He wrote: 'I have been requested to ... recommend a naturalist to go as companion to Captain Fitzroy, who has been commissioned by the government to survey the southern coasts of South America. I have stated that I consider you to be the best qualified person I know of who is likely to undertake such a situation. As far as the financial side of it is concerned, I have no notion. The voyage is to last two years ... ' "
"How can you remember all that by heart?"
"A bagatelle, Sophie."
"And what did he answer?"
"He wished ardently to grasp the chance, but in those days young men did nothing without their parents' consent. After much persuasion, his father finally agreed-- and it was he who financed his son's voyage. As far as the 'financial side' went, it was conspicuous by its absence."
"Oh."
"The ship was the naval vessel HMS Beagle. It sailed from Plymouth on December 27, 1831, bound for South America, and it did not return until October of 1836. The two years became five and the voyage to South America turned into a voyage round the world. And now we come to one of the most important voyages of discovery in recent times."
"They sailed all the way round the world?"
"Yes, quite literally. From South America they sailed on across the Pacific to New Zealand, Australia, and South Africa. Then they sailed back to South America before setting sail for England. Darwin wrote that the voyage on board the Beagle was without doubt the most significant event in his life."
"It couldn't have been easy to be a naturalist at sea."
"For the first years, the Beagle sailed up and down the coast of South America. This gave Darwin plenty of opportunity to familiarize himself with the continent, also inland. The expedition's many forays into the Galapagos Islands in the Pacific west of South America were of decisive significance as well. He was able to collect and send to England vast amounts of material. However, he kept his reflections on nature and the evolution of life to himself. When he returned home at the age of twenty-seven, he found himself renowned as a scientist. At that point he had an inwardly clear picture of what was to become his theory of evolution. But he did not publish his main work until many years after his return, for Darwin was a cautious man--as is fitting for a scientist."
"What was his main work?"
"Well, there were several, actually. But the book-which gave rise to the most heated debate in England was The Origin of Species, published in 1859. Its full title was On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. The long title is actually a complete resume of Darwin's theory."
"He certainly packed a lot into one title."
"But let's take it piece by piece. In The Origin of Species, Darwin advanced two theories or main theses: first, he proposed that all existing vegetable and animal forms were descended from earlier, more primitive forms by way of a biological evolution. Secondly, that evolution was the result of natural selection."
"The survival of the fittest, right?"
"That's right, but let us first concentrate on the idea of evolution. This, in itself, was not all that original. The idea of biological evolution began to be widely accepted in some circles as early as 1800. The leading spokesman for this idea was the French zoologist Lamarck. Even before him, Darwin's own grandfather, Erasmus Darwin, had suggested that plants and animals had evolved from some few primitive species. But none of them had come up with an acceptable explanation as to how this evolution happened. They were therefore not considered by churchmen to be any great threat."
"But Darwin was?"
"Yes, indeed, and not without reason. Both in ecclesiastic and scientific circles, the Biblical doctrine of the immutability of all vegetable and animal species was strictly adhered to. Each and every form of animal life had been created separately once and for all. This Christian view was moreover in harmony with the teachings of Plato and Aristotle."
"How so?"
"Plato's theory of ideas presupposed that all animal species were immutable because they were made after patterns of eternal ideas or forms. The immutability of animal species was also one of the cornerstones of Aristotle's philosophy. But in Darwin's time there were a number of observations and finds which were putting traditional beliefs to the test."
"What kind of observations and finds were they?"
"Well, to begin with an increasing number of fossils were being dug out. There were also finds of large fossil bones from extinct animals. Darwin himself was puzzled to find traces of sea creatures far inland. In South America he made similar discoveries high up in the mountains of the Andes. What is a sea creature doing in the Andes, Sophie? Can you tell me that?"
"No."
"Some believed that they had just been thrown away there by humans or animals. Others believed that God had created these fossils and traces of sea creatures to lead the ungodly astray."
"But what did scientists believe?"
"Most geologists swore to a 'catastrophe theory/ according to which the earth had been subjected to gigantic floods, earthquakes, and other catastrophes that had destroyed all life. We read of one of these in the Bible--the Flood and Noah's Ark. After each catastrophe, God renewed life on earth by creating new--and more perfect-- plants and animals."
"So the fossils were imprints of earlier life forms that had been wiped out after these gigantic catastrophes?"
"Precisely. For example, it was thought that fossils were imprints of animals that had failed to get into the Ark. But when Darwin set sail on the Beagle, he had with him the first volume of the English biologist Sir Charles Lyell's Principles of Geology. Lyell held that the present geology of the earth, with its mountains and valleys, was the result of an interminably long and gradual evolution. His point was that even quite small changes could cause huge geological upheavals, considering the aeons of time that have elapsed."
"What kind of changes was he thinking of?"
"He was thinking of the same forces that prevail today: wind and weather, melting ice, earthquakes, and elevations of the ground level. You've heard the saying about a drop of water wearing away a stone--not by brute force, but by continuous dripping. Lyell believed that similar tiny and gradual changes over the ages could alter the face of nature completely. However, this theory alone could not explain why Darwin found the remains of sea creatures high up in the Andes. But Darwin always remembered that tiny gradual changes could result in dramatic alterations if they were given sufficient time."
"I suppose he thought the same explanation could be used for the evolution of animals."
"Yes, that was his thought. But as I said before, Darwin was a cautious man. He posed questions long before he ventured to answer them. In that sense he used the same method as all true philosophers: it is important to ask but there is no haste to provide the answer."
"Yes, I see."
"A decisive factor in Lyell's theory was the age of the earth. In Darwin's time, it was widely believed that about 6,000 years had elapsed since God created the earth. That figure had been arrived at by counting the generations since Adam and Eve."
"How naive!"
"Well, it's easy to be wise after the event. Darwin figured the age of the earth to be 300 million years. Because one thing, at least, was clear: neither Lyell's theory of gradual geological evolution nor Darwin's own theory of evolution had any validity unless one reckoned with tremendously long periods of time."
"How old is the earth?"
"Today we know that the earth is 4.6 billion years old."
"Wow!"
"Up to now, we have looked at one of Darwin's arguments for biological evolution, namely, the stratified deposits of fossils in various layers of rock. Another argument was the geographic distribution of living species. This was where Darwin's scientific voyage could contribute new and extremely comprehensive data. He had seen with his own eyes that the individuals of a single species of animal within the same region could differ from each other in only the minutest detail. He made some very interesting observations on the Galapagos Islands, west of Ecuador, in particular."
"Tell me about them."
"The Galapagos Islands are a compact group of volcanic islands. There were therefore no great differences in the plant and animal life there. But Darwin was interested in the tiny differences. On all the islands, he came across giant tortoises that were slightly different from one island to another. Had God really created a separate race of tortoises for each and every island?"
"It's doubtful."
"Darwin's observations of bird life on the Galapagos were even more striking. The Galapagos finches were clearly varied from island to island, especially as regards the shape of the beak. Darwin demonstrated that these variations were closely linked to the way the finches found their food on the different islands. The ground finches with steeply profiled beaks lived on pine cone seeds, the little warbler finches lived on insects, and the tree finches lived on termites extracted from bark and branches ... Each and every one of the species had a beak that was perfectly adapted to its own food intake. Could all these finches be descended from one and the same species? And had the finches adapted to their surroundings on the different islands over the ages in such a way that new species of finches evolved?"
"That was the conclusion he came to, wasn't it?"
"Yes. Maybe that was where Darwin became a 'Darwinist'--on the Galapagos Islands. He also observed that the fauna there bore a strong resemblance to many of the species he had seen in South America. Had God once and for all really created all these animals slightly different from each other--or had an evolution taken place? Increasingly, he began to doubt that all species were immutable. But he still had no viable explanation as to how such an evolution had occurred. But there was one more factor to indicate that all the animals on earth might be related."
"And what was that?"
"The development of the embryo in mammals. If you compare the embryos of dogs, bats, rabbits, and humans at an early stage, they look so alike that it is hard to tell the difference. You cannot distinguish a human embryo from a rabbit embryo until a very late stage. Shouldn't this indicate that we are distant relatives?"
"But he had still no explanation of how evolution happened?"
"He pondered constantly on [yell's theory of the minute changes that could have great effect over a long period of time. But he could find no explanation that would apply as a general principle. He was familiar with the theory of the French zoologist Lamarck, who had shown that the different species had developed the characteristics they needed. Giraffes, for example, had developed long necks because for generations they had reached up for leaves in the trees. Lamarck believed that the characteristics each individual acquires through his own efforts are passed on to the next generation. But this theory of the heredity of 'acquired characteristics' was rejected by Darwin because Lamarck had no proof of his bold claims. However, Darwin was beginning to pursue another, much more obvious line of thought. You could almost say that the actual mechanism behind the evolution of species was right in front of his very nose."
"So what was it?"
"I would rather you worked the mechanism out for yourself. So I ask: If you had three cows, but only enough fodder to keep two of them alive, what would you do?"
"I suppose I'd have to slaughter one of them."
"All right... which one would you slaughter?"
"I suppose I'd slaughter the one that gave the least milk."
"Would you?"
"Yes, that's logical, isn't it?"
"That is exactly what mankind had done for thousands of years. But we haven't finished with your two cows yet. Suppose you wanted one of them to calve. Which one would you choose?"
"The one that was the best milker. Then its calf would probably be a good milker too."
"You prefer good milkers to bad, then. Now there's one more question. If you were a hunter and you had two gundogs, but had to give up one of them, which one would you keep?"
"The one that's best at finding the kind of game I shoot, obviously."
"Quite so, you would favor the better gundog. That's exactly how people have bred domestic animals for more than ten thousand years, Sophie. Hens did not always lay five eggs a week, sheep did not always yield as much wool, and horses were not always as strong and swift as they are now. Breeders have made an artificial selection. The same applies to the vegetable kingdom. You don't plant bad potatoes if there are good seed potatoes available, and you don't waste time cutting wheat that yields no grain. Darwin pointed out that no cows, no stalks of wheat, no dogs, and no finches are completely alike. Nature produces an enormous breadth of variation. Even within the same species, no two individuals are exactly alike. You probably experienced that for yourself when you drank the blue liquid."
"I'll say."
"So now Darwin had to ask himself: could a similar mechanism be at work in nature too? Is it possible that nature makes a 'natural selection' as to which individuals are to survive? And could such a selection over a very long period of time create new species of flora and fauna?"
"I would guess the answer is yes."
"Darwin could still not quite imagine how such a natural selection could take place. But in October 1838, exactly two years after his return on the Beagle, he chanced to come across a little book by the specialist in population studies, Thomas Malthus. The book was called An Essay on the Principle of Population. Malthus got the idea for this essay from Benjamin Franklin, the American who in-vented the lightning conductor among other things. Franklin had made the point that if there were no limiting factors in nature, one single species of plant or animal would spread over the entire globe. But because there are many species, they keep each other in balance."
"I can see that."
"Malthus developed this idea and applied it to the world's population. He believed that mankind's ability to procreate is so great that there are always more children born than can survive. Since the production of food can never keep pace with the increase in population, he believed that huge numbers were destined to succumb in the struggle for existence. Those who survived to grow up-- and perpetuate the race--would therefore be those who came out best in the struggle for survival."
"That sounds logical."
"But this was actually the universal mechanism that Darwin had been searching for. Here was the explanation of how evolution happens. It was due to natural selection in the struggle for life, in which those that were best adapted to their surroundings would survive and perpetuate the race. This was the second theory which he proposed in The Origin of Species. He wrote: The elephant is reck-oned the slowest breeder of all known animals,' but if it had six young and survived to a hundred, 'after a period of from 740 to 750 years there would be nearly nineteen million elephants alive, descended from the first pair.' "
"Not to mention all the thousands of cods' eggs from a single cod."
"Darwin further proposed that the struggle for survival is frequently hardest among species that resemble each other the most. They have to fight for the same food. There, the slightest advantage--that is to say, the infinitesimal variation--truly comes into its own. The more bitter the struggle for survival, the quicker will be the evolution of new species, so that only the very best adapted will survive and the others will die out."
"The less food there is and the bigger the brood, the quicker evolution happens?"
"Yes, but it's not only a question of food. It can be just as vital to avoid being eaten by other animals. For example, it can be a matter of survival to have a protective camouflage, the ability to run swiftly, to recognize hostile animals, or, if the worst comes to the worst, to have a repellent taste. A poison that can kill predators is quite useful too. That's why so many cacti are poisonous, Sophie. Practically nothing else can grow in the desert, so this plant is especially vulnerable to plant-eating animals."
"Most cacti are prickly as well."
"The ability to reproduce is also of fundamental importance, obviously. Darwin studied the ingenuity of plant pollination in great detail. Flowers glow in glorious hues and exude delirious scents to attract the insects which are instrumental in pollination. To perpetuate their kind, birds trill their melodious tones. A placid or melancholy bull with no interest in cows will have no interest for genealogy either, since with characteristics like these, its line will die out at once. The bull's sole purpose in life is to grow to sexual maturity and reproduce in order to propagate the race. It is rather like a relay race. Those that for one reason or another are unable to pass on their genes are continually discarded, and in that way the race is continually refined. Resistance to disease is one of the most important characteristics progressively accumulated and preserved in the variants that survive."
"So everything gets better and better?"
"The result of this continual selection is that the ones best adapted to a particular environment--or a particular ecological niche--will in the long term perpetuate the race in that environment. But what is an advantage in one environment is not necessarily an advantage in another. For some of the Galapagos finches, the ability to fly was vital. But being good at flying is not so necessary if food is dug from the ground and there are no predators. The reason why so many different animal species have arisen over the ages is precisely because of these many niches in the natural environment."
"But even so, there is only one human race."
"That's because man has a unique ability to adapt to different conditions of life. One of the things that amazed Darwin most was the way the Indians in Tierra del Fuego managed to live under such terrible climatic conditions. But that doesn't mean that all human beings are alike. Those who live near the equator have darker skins than people in the more northerly climes because their dark skin protects them from the sun. White people who expose themselves to the sun for long periods are more prone to skin cancer."
"Is it a similar advantage to have white skin if you live in northern countries?"
"Yes, otherwise everyone on earth would be dark-skinned. But white skin more easily forms sun vitamins, and that can be vital in areas with very little sun. Nowa-days that is not so important because we can make sure we have enough sun vitamins in our diet. But nothing in nature is random. Everything is due to infinitesimal changes that have taken effect over countless generations."
"Actually, it's quite fantastic to imagine."
"It is indeed. So far, then, we can sum up Darwin's theory of evolution in a few sentences."
"Go ahead!"
"We can say that the 'raw material' behind the evolution of life on earth was the continual variation of individuals within the same species, plus the large number of progeny, which meant that only a fraction of them survived, the actual 'mechanism,' or driving force, behind evolution was thus the natural selection in the struggle for survival. This selection ensured that the strongest, or the 'fittest,' survived."
"It seems as logical as a math sum. How was The Origin of Species received?"
"It was the cause of bitter controversies. The Church protested vehemently and the scientific world was sharply divided. That was not really so surprising. Darwin had, after all, distanced God a good way from the act of creation, although there were admittedly some who claimed it was surely greater to have created something with its own innate evolutionary potential than simply to create a fixed entity."
Suddenly Sophie jumped up from her chair.
"Look out there!" she cried.
She pointed out of the window. Down by the lake a man and a woman were walking hand in hand. They were completely naked.
"That's Adam and Eve," said Alberto. "They were gradually forced to throw in their lot with Little Red Rid-inghood and Alice in Wonderland. That's why they have turned up here."
Sophie went to the window to watch them, but they soon disappeared among the trees.
"Because Darwin believed that mankind was descended from animals?"
"In 1871 Darwin published The Descent of Man, in which he drew attention to the great similarities between humans and animals, advancing the theory that men and anthropoid apes must at one time have evolved from the same progenitor. By this time the first fossil skulls of an extinct type of man had been found, first in the Rock of Gibraltar and some years later in Neanderthal in Germany. Strangely enough, there were fewer protests in T871 than in 1859, when Darwin published The Origin of Species. But man's descent from animals had been implicit in the first book as well. And as I said, when Darwin died in 1882, he was buried with all the ceremony due to a pioneer of science."
"So in the end he found honor and dignity?"
"Eventually, yes. But not before he had been described as the most dangerous man in England."
"Holy Moses!"
" 'Let us hope it is not true,' wrote an upper-class lady, 'but if it is, let us hope it will not be generally known.' A distinguished scientist expressed a similar thought: 'An embarrassing discovery, and the less said about it the better.' "
"That was almost proof that man is related to the ostrich!"
"Good point. But that's easy enough for us to say now. People were suddenly obliged to revise their whole approach to the Book of Genesis. The young writer John Ruskin put it like this: 'If only the geologists would leave me alone. After each Bible verse I hear the blows of their hammers.' "
"And the blows of the hammers were his doubts about the word of God?"
"That was presumably what he meant. Because it was more than the literal interpretation of the story of creation that toppled. The essence of Darwin's theory was the utterly random variations which had finally produced Man. And what was more, Darwin had turned Marv into a product of something as unsentimental as the struggle for existence."
"Did Darwin have anything to say about how such random variations arose?"
"You've put your finger on the weakest point in his theory. Darwin had only the vaguest idea of heredity. Something happens in the crossing. A father and mother never get two identical offspring. There is always some slight difference. On the other hand it's difficult to produce anything really new in that way. Moreover, there are plants and animals which reproduce by budding or by simple cell division. On the question of how the variations arise, Darwin's theory has been supplemented by the so-called neo-Darwinism."
"What's that?"
"All life and all reproduction is basically a matter of cell division. When a cell divides into two, two identical cells are produced with exactly the same hereditary factors. In cell division, then, we say a cell copies itself."
"Yes?"
"But occasionally, infinitesimal errors occur in the process, so that the copied cell is not exactly the same as the mother cell. In modern biological terms, this is a mutation. Mutations are either totally irrelevant, or they can lead to marked changes in the behavior of the individual. They can be directly harmful, and such 'mutants' will be continually discarded from the large broods. Many diseases are in fact due to mutations. But sometimes a mutation can give an individual just that extra positive characteristic needed to hold its own in the struggle for existence."
"Like a longer neck, for instance?"
"Lamarck's explanation of why the giraffe has such a long neck was that giraffes have always had to reach upwards. But according to Darwinism, no such inherited characteristic would be passed on. Darwin believed that the giraffe's long neck was the result of a variation. Neo-Darwinism supplemented this by showing a clear cause of just that particular variation."
"Mutations?"
"Yes. Absolutely random changes in hereditary factors supplied one of the giraffe's ancestors with a slightly longer neck than average. When there was a limited supply of food, this could be vital enough. The giraffe that could reach up highest in the trees managed best. We can also imagine how some such 'primal giraffes' evolved the ability to dig in the ground for food. Over a very long period of time, an animal species, now long extinct, could have divided itself into two species. We can take some more recent examples of the way natural selection can work."
"Yes, please."
"In Britain there is a certain species of butterfly called the peppered moth, which lives on the trunks of silver birches. Back in the eighteenth century, most peppered moths were silvery gray. Can you guess why, Sophie?"
"So they weren't so easy for hungry birds to spot."
"But from time to time, due to quite chance mutations, some darker ones were born. How do you think these darker variants fared?"
"They were easier to see, so they were more easily snapped up by hungry birds."
"Yes, because in that environment--where the birch trunks were silver--the darker hue was an unfavorable characteristic. So it was always the paler peppered moths that increased in number. But then something happened in that environment. In several places, the silvery trunks became blackened by industrial soot. What do you think happened to the peppered moths then?"
"the darker ones survived best."
"Yes, so now it wasn't long before they increased in number. From 1848 to 1948, the proportion of dark peppered moths increased from 1 to 99 percent in certain places. The environment had changed, and it was no longer an advantage to be light. On the contrary. The white 'losers' were weeded out with the help of the birds as soon as they appeared on the birch trunks. But then something significant happened again. A decrease in the use of coal and better filtering equipment in the factories has recently produced a cleaner environment."
"So now the birches are silver again?"
"And therefore the peppered moth is in the process of returning to its silvery color. This is what we call adaptation. It's a natural law."
"Yes, I see."
"But there are numerous examples of how man interferes in the environment."
"Like what?"
"For example, people have tried to eradicate pests with various pesticides. At first, this can produce excellent results. But when you spray a field or an orchard with pesticides, you actually cause a miniature ecocatastrophe for the pests you are trying to eradicate. Due to continual mutations, a type of pest develops that is resistant to the pesticide being used. Now these 'winners' have free play, so it becomes harder and harder to combat certain kinds of pest simply because of man's attempt to eradicate them. The most resistant variants are the ones that survive, of course."
"That's pretty scary."
"It certainly is food for thought. We also try to combat parasites in our own bodies in the form of bacteria."
"We use penicillin or other kinds of antibiotic."
"Yes, and penicillin is also an ecocatastrophe for the little devils. However, as we continue to administer penicillin, we are making certain bacteria resistant, thereby cultivating a group of bacteria that is much harder to combat than it was before. We find we have to use stronger and stronger antibiotics, until . . ."
"Until they finally crawl out of our mouths? Maybe we ought to start shooting them?"
"That might be a tiny bit exaggerated. But it is clear that modern medicine has created a serious dilemma. The problem is not only that a single bacterium has become more virulent. In the past, there were many children who never survived--they succumbed to various diseases. Sometimes only the minority survived. But in a sense modern medicine has put natural selection out of commission. Something that has helped one individual over a serious illness can in the long run contribute to weakening the resistance of the whole human race to certain diseases. If we pay absolutely no attention to what is called hereditary hygiene, we could find ourselves facing a degeneration of the human race. Mankind's hereditary potential for re-sisting serious disease will be weakened."
"What a terrifying prospect!"
"But a real philosopher must not refrain from pointing out something 'terrifying' if he otherwise believes it to be true. So let us attempt another summary."
"Okay."
"You could say that life is one big lottery in which only the winning numbers are visible."
"What on earth do you mean?"
"Those that have lost in the struggle for existence have disappeared, you see. It takes many millions of years to select the winning numbers for each and every species of vegetable and animal on the earth. And the losing numbers--well, they only make one appearance. So there are no species of animal or vegetable in existence today that are not winning numbers in the great lottery of life."
"Because only the best have survived."
"Yes, that's another way of saying it. And now, if you will kindly pass me the picture which that fellow--that zookeeper--brought us . . ."
Sophie passed the picture over to him. The picture of Noah's Ark covered one side of it. The other was devoted to a tree diagram of all the various species of animals. This was the side Alberto was now showing her.
"Our Darwinian Noah also brought us a sketch that shows the distribution of the various vegetable and animal species. You can see how the different species belong in the different groups, classes, and subkingdoms."
"Yes."
"Together with monkeys, man belongs to the so-called primates. Primates are mammals, and all mammals belong to the vertebrates, which again belong to the multi-cellular animals."
"It's almost like Aristotle."
"Yes, that's true. But the sketch illustrates not only the distribution of the different species today. It also tells something of the history of evolution. You can see, for example, that birds at some point parted from reptiles, and that reptiles at some point parted from amphibia, and that amphibia parted from fishes."
"Yes, it's very clear."
"Every time a line divides into two, it's because mutations have resulted in a new species. That is how, over the ages, the different classes and subkingdoms of animals arose. In actual fact there are more than a million animal species in the world today, and this million is only a fraction of the species that have at some time lived on the earth. You can see, for instance, that an animal group such as the Trilobita is totally extinct."
"And at the bottom are the monocellular animals."
"Some of these may not have changed in two billion years. You can also see that there is a line from these monocellular organisms to the vegetable kingdom. Because in all probability plants come from the same primal cell as animals."
"Yes, I see that. But there's something that puzzles me."
"Yes?"
"Where did this first primal cell come from? Did Darwin have any answer to that?"
"I said, did I not, that he was a very cautious man. But as regards that question, he did permit himself to propose what one might call a qualified guess. He wrote:
If (and O, what an if!) we could picture some hot little pool in which all manner of ammoniacal and phosphorous salts, light, heat, electricity and so forth were present, and that a protein compound were to be chemically formed in it, ready to undergo even more complicated changes ..."
"What then?"
"What Darwin was philosophizing on here was how the first living cell might have been formed out of inorganic matter. And again, he hit the nail right on the head. Scientists of today think the first primitive form of life arose in precisely the kind of 'hot little pool' that Darwin pictured."
"Go on."
"That will have to suffice because we're leaving Darwin now. We're going to jump ahead to the most recent findings about the origins of life on earth."
"I'm rather apprehensive. Does anybody really know how life began?"
"Maybe not, but more and more pieces of the puzzle have fallen into place to form a picture of how it may have begun."
"Well?"
"Let us first establish that all life on earth--both animal and vegetable--is constructed of exactly the same substances. The simplest definition of life is that it is a substance which in a nutrient solution has the ability to subdivide itself into two identical parts. This process is governed by a substance we call DNA. By DNA we mean the chromosomes, or hereditary structures, that are found in all living cells. We also use the term DNA molecule, because DNA is in fact a complex molecule--or macro-molecule. The question is, then, how the first molecule arose."
"Yes?"
"The earth was formed when the solar system came into being 4.6 billion years ago. It began as a glowing mass which gradually cooled. This is where modern science believes life began between three and four billion years ago."
"It sounds totally improbable."
"Don't say that before you have heard the rest. First of all, our planet was quite different from the way it looks today. Since there was no life, there was no oxygen in the atmosphere. Free oxygen was first formed by the photosynthesis of plants. And the fact that there was no oxygen is important. It is unlikely that life cells--which, again, can form DNA--could have arisen in an atmosphere containing oxygen."
"Why?"
"Because oxygen is strongly reactive. Long before complex molecules like DNA could be formed, the DNA molecular cells would be oxydized."
"Really."
"That is how we know for certain that no new life arises today, not even so much as a bacterium or a virus. All life on earth must be exactly the same age. An elephant has just as long a family tree as the smallest bacterium. You could almost say that an elephant--or a human being-- is in reality a single coherent colony of monocellular creatures. Because each cell in our body carries the same hereditary material. The whole recipe of who we are lies hidden in each tiny cell."
"That's an odd thought."
"One of life's great mysteries is that the cells of a multicellular animal have the ability to specialize their function in spite of the fact that not all the different hereditary characteristics are active in all the cells. Some of these characteristics--or genes--are 'activated' and others are 'deactivated.' A liver cell does not produce the same proteins as a nerve cell or a skin cell. But all three types of cell have the same DMA molecule, which contains the whole recipe for the organism in question.
"Since there was no oxygen in the atmosphere, there was no protective ozone layer around the earth. That means there was nothing to stop the radiation from the cosmos. This is also significant because this radiation was probably instrumental in forming the first complex molecule. Cosmic radiation of this nature was the actual energy which caused the various chemical substances on the earth to start combining into a complicated macro-molecule."
"Okay."
"Let me recapitulate: Before such complex molecules, of which all life consists, can be formed, at least two conditions must be present: there must be no oxygen in the atmosphere, and there must be access for cosmic radiation."
"I get it."
"In this 'hot little pool'--or primal soup, as it is often called by modern scientists--there was once formed a gigantically complicated macromolecule, which had the wondrous property of being able to subdivide itself into two identical parts. And so the long evolutionary process began, Sophie. If we simplify it a bit, we can say that we are now talking of the first hereditary material, the first DNA or the first living cell. It subdivided itself again and again--but from the very first stage, transmutation was occurring. After aeons of time, one of these monocellular organisms connected with a more complicated multicel-lular organism. Thus the photosynthesis of plants also began, and in that way the atmosphere came to contain oxygen. This had two results: first, the atmosphere permitted the evolution of animals that could breathe with the aid of lungs. Secondly, the atmosphere protected life from the harmful cosmic radiation. Strangely enough, this radiation, which was probably a vital 'spark' in the formation of the first cell, is also harmful to all forms of life."
"But the atmosphere can't have been formed overnight. How did the earliest forms of life manage?"
"Life began in the primal 'seas'--which are what we mean by primal soup. There it could live protected from the harmful rays. Not until much later, when life in the oceans had formed an atmosphere, did the first amphibians crawl out onto land. The rest is what we have already talked about. And here we are, sitting in a hut in the woods, looking back on a process that has taken three or four billion years. And in us, this long process has finally become aware of itself."
"And yet you don't think it all happened quite accidentally?"
"I never said that. The picture on this board shows that evolution had a direction. Across the aeons of time animals have evolved with increasingly complicated nerve systems--and an ever bigger brain. Personally, I don't think that can be accidental. What do you think?"
"It can't be pure chance that created the human eye. Don't you think there is meaning in our being able to see the world around us?"
"Funnily enough, the development of the eye puzzled Darwin too. He couldn't really come to terms with the fact that something as delicate and sensitive as an eye could be exclusively due to natural selection."
Sophie sat looking up at Alberto. She was thinking how odd it was that she should be alive now, and that she only lived this one time and would never again return to life. Suddenly she exclaimed:
What matters our creative endless toil, When, at a snatch, oblivion ends the coil?
Alberto frowned at her.
"You must not talk like that, child. Those are the words of the Devil."
"The Devil?"
"Or Mephistopheles--in Goethe's Faust 'Was soil uns denn das ew'ge Schaffen! Geschaffenes zu nichts hinweg-zuraffenV "
"But what do those words mean exactly?" "As Faust dies and looks back on his life's work, he says in triumph:
Then to the moment could I say:
Linger you now, you are so fair!
Now records of my earthly dayNo flights of aeons can impair--Foreknowledge comes, and fills me with such bliss,I take my joy, my highest moment this."
"That was very poetic."
"But then it's the Devil's turn. As soon as Faust dies, he exclaims:
A foolish word, bygone.
How so then, gone?
Gone, to sheer Nothing, past with null made one!
What matters creative endless toil,When, at a snatch, oblivion ends the coil?
'It is bygone'--How shall this riddle run?
As good as if things never had begun,Yet circle back, existence to possess:
I'd rather have Eternal Emptiness."
"That's pessimistic. I liked the first passage best. Even though his life was over, Faust saw some meaning in the traces he would leave behind him."
"And is it not also a consequence of Darwin's theory that we are part of something all-encompassing, in which every tiny life form has its significance in the big picture? We are the living planet, Sophie! We are the great vessel sailing around a burning sun in the universe. But each and every one of us is also a ship sailing through life with a cargo of genes. When we have carried this cargo safely to the next harbor--we have not lived in vain. Thomas Hardy expresses the same thought in his poem Transformations':
Portion of this yew
Is a man my grandsire knew,
Bosomed here at its foot:
This branch may be his wife,
A ruddy human life
Now turned to a green shoot.
These grasses must be made
Of her who often prayed,
Last century, for repose;
And the fair girl long ago
Whom I often tried to know
May be entering this rose.
So, they are not underground,
But as nerves and veins abound
In the growths of upper air,
And they feel the sun and rain,
And the energy again
That made them what they were!"
"That's very pretty."
"But we will talk no more. I simply say next chapter!'
"Oh, stop all that irony!"
"New chapter, I said! I shall be obeyed!"
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