Dougal Dixon "Man after man. An anthropology of the future" Introduction - evolution and man
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INTRODUCTION – EVOLUTION AND MAN

Evolution is the process that brought us to where we are today.
It started about 3500 million years ago, when the first living thing, probably a single complex organic molecule in the form of a long chain, began to reproduce itself. It did this by latching onto simpler molecules dissolved in the water around it, until it built up a mirror image of itself. The two parts then split apart to become two identical complex molecules. Each of these had the same power of attracting simpler molecules and building up a mirror image – similar to the way in which viruses reproduce themselves.
The building up and the splitting took place untold millions of times. Inevitably on occasion the mirror image so produced was not accurate. As a result the new molecule had slightly different properties from the old, and may not have been so efficient at reproducing itself. In this case the changed molecule - the mutation - stopped reproducing and died out.
However, the occasional mutation arose that actually helped the molecule to reproduce itself. The mirror images – the off spring – of this mutation then survived. This is the basis of the process that we call evolution.
After millions of beneficial chance mutations the single molecule became more and more complex, if complexity ensured a more efficient reproductive process. The molecule changed from a virus-like entity to a living cell, in which the reproductive molecule or molecules were encased and protected by an outer membrane. This resembled one of our modern bacteria.
The chemical reactions that enabled early molecules to reproduce themselves may have been insufficient to power the reproduction of more advanced creatures, and other energy sources developed that allowed the absorption of energy from sunlight and the use of this energy to build up raw materials for reproduction. The first single-celled plants had evolved.
Other mutated cells did not use the sun’s energy. Instead they digested the cells that did, and so used the energy already stored. These were the first animals.
Eventually creatures evolved that consisted of more than just a single cell. This came about either by cells reproducing themselves and then failing to split, or by several cells coming together. Whichever it was, if the multi-celled creature were more efficient, then it survived and reproduced in its multi-cellular form.
With the increasing complexity, the different cells in a single creature evolved to have different functions. Some cells were involved in sense, helping the creature to find food or light. Other cells were involved in locomotion, in moving the whole creature towards its food or its light source. Others were involved in digestion, others in reproduction, and so on.
The different masses of cells are what we call tissues, and the structures that they form, each with a different function, are called organs. An entire creature (made up from molecules that make cells, that make tissues, that make organs) is called an organism.
At an early stage the pathways of evolution began to branch, and different types of organism developed. Wherever there was a food source that could be exploited, evolution produced an organism able to exploit it. Such a process is called adaptive radiation, and we can see it at work today.
Many species of finch live in the Galapagos Islands, off the west coast of South America. These all evolved from one type of seed-eating ground finch that came over from the mainland, and spread to all the islands, each with different habitats and food sources. The finches on each island evolved to take advantage of their particular habitat. As a result there are now many species of finch on the islands, including heavy-beaked forms that eat seeds, short-beaked forms that eat buds and fruit and long-beaked forms that eat insects.
Environments are not stable; they change for one reason or another. When this happens, a creature evolved to live in a particular way in a certain environment becomes extinct. For example, if all the insects on the Galapagos Islands died out, then the long-beaked finches would become extinct: a process known as natural selection. If the insects became extinct, their places would be taken by another creature, and some other bird would evolve to eat that.
Evolution produces specific shapes of animals to live in particular environments. Grass is tough to eat, so an animal that eats grass needs strong teeth and a specialized digestive system. Grasslands are wide open areas in which danger can be seen coming from a long way away, and there are no hiding places. A grass-eating animal, therefore, tends to have long running legs, as well as strong teeth, and a long face so that its eyes are above the level of the grass while its head is down eating. This gives us the shape of the antelope – the typical grass-eating animal of Africa.
However, the grasslands of Australia have evolved a quite unrelated grass-eating animal – the kangaroo. There seems little resemblance between this and the antelope of Africa. It does, however, have the same long face with similar grass-grinding teeth; and the legs are long and built for speed, albeit in a bounding rather than a running gait. This development of similar features in unrelated animals in response to similar environmental conditions is what is known as convergent evolution. It accounts for the similarities between seals and sealions, aardvarks and anteaters, ants and termites, vultures and condors.
A similar phenomenon is parallel evolution. In this, two branches of the same family tree develop along similar lines independently of one another. For example, the kit fox of North America and the fennec fox of Africa are both small, with a sandy pelt and large ears. The ears act as cooling vanes and prevent each animal overheating in its desert environment, and the pelt is camouflage. Both are descended from a more conventional fox-like animal, but each has evolved separately to live in different deserts.
The different colours and patterns in animals can also be attributed to evolutionary processes. Animal patterns may camouflage them: on the other hand they may, like the skunk, have striking colours that warn a would-be attacker that the owner is poisonous. Some animals mimic others, as when a harmless king snake develops the spectacular pattern of the poisonous coral snake, and consequently turns away potential enemies. All these have developed because the animals concerned have benefited from them, have survived and have gone on to reproduce.
Throughout the world and throughout time, animals and plants have changed in response to the changes in the environment.
One species has broken with this tradition. Within the last million years or so the human species Homo sapiens evolved. It has come all the way from molecules to its present form in 3500 million years by the workings of evolution. Now, within the last few millennia, intelligence has developed, and with it cultures and civilizations. The species has spread not by changing to adapt to the environments it found but by changing the environments to suit itself. Instead of developing furry pelts and layers of insulating fat to adapt to cold conditions, it manufactures artificial coverings and uses available energy supplies to generate heat for the body. Instead of evolving heat radiating structures such as big ears to adapt to hot conditions, it manufactures refrigeration and air-conditioning systems, again using available energy supplies. Instead of developing speed and killing strategies that allow it to hunt a particular food, it builds machines to do it. By using its intelligence it can exploit all food supplies in all environments without having to change itself.
Medical science eliminates much of the effects of natural selection: no longer does an individual not particularly well adapted to the environment die out before being able to reproduce.
Under natural conditions not all offspring of a species survive, and this is reflected in the birth-rate. Thanks to medical science, more offspring of Homo sapiens survive than ever could before, but this has not been reflected in a corresponding drop in the birth-rate. As a result the populations of Homo sapiens are growing without the refining and modifying processes of natural selection.
Evolution as we know it for Homo sapiens has stopped. However, this does not mean that the process of change has necessarily stopped.
As science develops, the reproductive molecules - the genes - that exist within every cell of the human body are becoming better and better understood. When Homo sapiens finally appreciates which parts control the development of which features, then the possibility exists for modifying the process. A stage will be reached when one gene can be suppressed, another encouraged, with yet another created from new. A human being with particular features, following a particular preconceived plan, may be born from modified sperm cells and ova. Without the natural processes of modification, this unnatural process is the only way of developing the species into new forms to face the problems that await it in the future: problems generated by overpopulation, over-use of natural resources and pollution.

Genetic engineering

The mechanics of genetic engineering are already complex, yet in their current state they are primitive compared to what will undoubtedly be possible within a few decades.
The reproductive molecules that lie at the nucleus of each cell of a living organism are in the form of long structures called chromosomes. These chromosomes are made up of the chemical substance DNA. Its shape is best imagined as a long ladder that has been twisted along its length. Each rung of this ladder consists of two compounds, called bases, locked together. There are only four different kinds of bases: thymine, cytosine, adenine and guanine, referred to as T, C, AS and G. A T always unites with an A, and а С always with a G. The sequence of these base pairs along the twisted ladder of the chromosome is almost infinitely variable – there are something like 6,000,000,000 bases in a full set of human chromosomes.
A chromosome is often described as a page in an instruction manual. Each base pair, or rung in the ladder, represents a letter of the alphabet, and the arrangement along the ladder gives ‘words’ and ‘sentences’. Each understandable instruction so formed gives a gene. The genes in a single cell produce the total information needed for the growth of the entire organism.
When an organism grows and develops, it does so by multiplication of cells. Each cell splits into two complete cells. When this happens, each chromosome in the cell actually splits down the middle. The uprights of the twisted ladder pull away from one another as the rungs split into two along the joins between the bases. What happens then is that these two half-ladders build up two complete ladders by attracting free bases made up from the chemicals drifting in the cell. As a result, when the cell splits into two each new cell carries exactly the same set of gene instructions.
The exception to this process is in sexual reproduction. Reproductive cells carry half the normal number of chromosomes. Two half-cells unite during fertilization to produce one cell with the full number. This new cell is a unique mix of genes, half from the mother and half from the father. This cell then divides in the usual manner until the entire organism is built up, following the instructions now carried in every cell.The big mystery now is this: how do the genes - the pattern of base pairs along a chromosome - actually work? How do they control the construction of an organism?
The idea behind genetic engineering is to manipulate natural processes. In some way genetic instructions along the chromosomes in a cell have to be identified then changed so that as the organism grows, it is to a new set of instructions. Since all the materials involved (cells, chromosomes, molecules) are microscopic, a whole new technology has to be applied.
Viruses can do it. Viruses essentially consist of a mass of their own DNA encased in an envelope. When they infect a cell they attach themselves to the cell’s wall and inject their DNA through it. In the cell’s interior the invading DNA breaks down the cell’s chromosomes and rebuilds the material into copies of itself.
For genetic engineers to do the same, they would first of all have to break in through the cell wall, then break down the DNA of the nucleus and reassemble it in the desired way. Alternatively, they could cut out segments of the DNA strand, segments that correspond to particular genes, and replace them with DNA segments already prepared. This would be done by chemicals that have specific biochemical reactions – enzymes – some of which have been found to have the ability to cut DNA strands.
The greatest experimental successes so far have been with bacteria. These single-celled creatures have cell walls that can be softened by chemical solutions so that new DNA can be placed inside. The double helix of the original chromosome can be chopped up using enzymes, and new DNA can be inserted. The broken ends of the DNA strands have one side longer than the other, exposing a sequence of bases. If the introduced DNA segment has matching bases exposed at its end the two DNA pieces will unite, Т to A, and С to G, and produce a complete chromosome. This technique is known as gene-splicing.
Before any of this can be attempted, however, the whole gene pattern has to be mapped. At the moment only about 100 human genes have been identified and interpreted; but, since genetics has only been in existence for a century, and the structure of the chromosome has only been known for about four decades, and scientific advance in this area is increasing exponentially, what was speculation about genetic engineering is quickly becoming fact.

Genetic engineering of human beings would consist of removing a reproductive cell from a human, altering a known gene in some predetermined way, and replacing the cell so that it grows to a full-term foetus with the desired characteristics.

1. The cell is removed.
2. The gene to be altered is identified on the chromosome.
3. It is replaced with a predetermined gene.
4. The cell is replaced in the womb.
5. An altered human being is born.

 

 

 

 

1. A human being is made of cells – about 10 trillion of them – all grown from a single reproductive cell.
2. Each cell contains a nucleus, carrying all the genetic information for growing the whole body.
3. The genetic information in the nucleus is arranged on a number of units called chromosomes.
4. Each chromosome is made up of a long strand of DNA coiled upon itself again and again.
5. A DNA strand is a twisted ladder of pairs of amino acid molecules, the sequence of which provides the genetic information.
6. When a cell reproduces, each DNA strand splits like a zip fastener along the joins between the amino acid molecules. Each half then builds up a complete strand by attracting to itself the free amino acid molecules drifting in the fluid of the cell.
 

CONTENTS

FOREWORD by Brian Aldiss 8
INTRODUCTION – EVOLUTION AND MAN 11
Genetic engineering 12
   

PART ONE:

 
IN THE BEGINNING 16
The Human Story So Far 16
8 MILLION YEARS AGO
16
3 MILLION YEARS AGO
16
2.5 MILLION YEARS AGO
16
1.5 MILLION YEARS AGO
17
500,000 YEARS AGO
17
15,000 YEARS AGO
17
5000 YEARS AGO
18
2000 YEARS AGO
18
1000 YEARS AGO
18
500 YEARS AGO
19
100 YEARS AGO 19
   

PART TWO:

 
MAN AFTER MAN 22
200 YEARS HENCE
Piccarblick the aquamorph
22
Cralym the vacuumorph
24
Jimez Smoot the space traveller
25
Kyshu Kristaan the squatty 29
300 YEARS HENCE
Haron Solto and his mechanical cradle
31
Greerath Hulm and the future
34
Hueh Chuum and his love
35
Aquatics 36
500 YEARS HENCE
Gram the engineered plains-dweller
37
Kule Taaran and the engineered forest-dweller
40
Knut the engineered tundra-dweller
42
Relia Hoolann and cultured cradles
43
Fiffe Floria and the Hitek
43
Carahudru and the woodland-dweller 48
1000 YEARS HENCE
Klimasen and the beginning of change
48
The end of Yamo
49
Weather patterns and the Tics
49
Plains-dwellers
52
Hoot, the temperate woodland-dweller
52
The end of Durian Skeel
53
Aquas 54
2000 YEARS HENCE
Rumm the forest-dweller
56
Larn the plains-dweller
58
Coom’s new friend
60
Yerok and the Tool 61
5000 YEARS HENCE
Trancer’s escape
62
Snatch and the tundra-dweller
63
Hrusha’s memory
64
Tropical tree-dwellers 66
10,000 YEARS HENCE
Symbionts
67
Hibernators
69
Leader of the clan
70
Disappearance of the plains
71
Cave-dwellers 71
50,000 YEARS HENCE
Families of plains-dwellers
72
The advancing desert
73
Islanders
74
Schools of aquatics
75
Melting ice 76
500,000 YEARS HENCE
Strings of socials
78
Boatbuilders 83
1 MILLION YEARS HENCE
Hunters and carriers
87
Aquatic harvesters 90
2 MILLION YEARS HENCE
Travellers
93
Hivers 96
3 MILLION YEARS HENCE
Fish-eaters
101
Tree-dwellers
106
Antmen
107
Desert-runners
108
Slothmen and spiketooths 111
5 MILLION YEARS HENCE
Moving stars 115
Builders 116
Emptiness 123
In the end is the beginning ... 123
   
Further Reading 124
   
Index