Evolution, a Quick Overview.
"The lapse of time has been so great as to be utterly inappreciable by the human intellect." (Charles Darwin ).
[top] Geological science (see reference books) began in the nineteenth century. Rock strata were classified early in the nineteenth century into Primary, Secondary and Tertiary. Primary rock, such as granite, was very old, devoid of fossils and crystalline, forming the core of mountain ranges. Limestone, sandstone and shale containing fossils made up Secondary rock. More recently formed and therefore surface Tertiary rock contained fossils of still extant creatures and was less consolidated, such as chalk (Mason, 1992). William Smith (1769-1839) started the science of stratigraphy , (see books) through his correlation of rock layers based on their fossil contents and other data.
By the end of the century, these classifications had changed. We still have three types of rock, but the time scales have been renamed. Our earth's history is divided into five lengths of time called eras. From youngest to oldest these are the Cenozoic, Mesozoic, Paleozoic, Proterozoic and Archaeozoic. Eras (see books) are divided into periods and periods into epochs. The Tertiary remained a major geological period, divided into six epochs. Replacing the Secondary was two eras, the Mesozoic and the Paleozoic, each further divided into a number of periods related to rock strata systems. The Primary geological division has been renamed the Precambrian Aeon, made up of two Eras, the Proterozoic and the Archean (Archeozoic). Today, the earth's crust is seen to be made up of three kinds of rocks, igneous (e.g., granite), sedimentary (e.g., shale) and metamorphic (e.g., gneiss). For a TABLE OF THE GEOLOGICAL TIME SCALE , in relation to evolution, please refer to Appendix 1 .
We need to understand the magnitude of TIME compared with the short duration of our lives. Even the appearance of humanity as a species is a very recent event compared to the history of life. If this article manages to achieve a better appreciation of relative time scales in relation to our behaviour, the future of our children and the long term survival of humanity on this planet, it will have achieved a sufficient purpose and contributed to holistic awareness. As Carl Sagan (1977) said, "And despite the insignificance of the instant we have so far occupied in cosmic time, it is clear that what happens on and near earth at the beginning of the second cosmic year will depend very much on the scientific wisdom and the DISTINCTLY HUMAN SENSITIVITY of mankind." Our (western) forebears of the nineteenth century believed creation to be a mere 4000 years old and the influence of this perspective still permeates our behaviour today. A conscious awareness of the actual time involved in the evolution of life needs to be incorporated into our culture and consciousness. Further, we need to look further ahead and include a time span encompassing thousands of years (Capra, 1982).
Humans seem to lack the ability to comprehend the time span of
evolution. To understand this book and evolutionary principles, it is
necessary to conceptualise this period. Our earth is
4,600,000,000 years old. Take a 460-page book to represent this
period, with each page representing 10 million years. The last page of
this book represents the beginning of creation and the first page,
recent time and the first letter, now.
Life began about 3.5 billion years (350 pages) ago, with the
fossils coming from rocks estimated to be (Horgan, 1993) 3200 to 3465
million years old (De Zanche & Mietto, 1979). By this time
micro-organisms had achieved a significant degree of complexity,
represented by fossil microbes 90 microns long and 20 microns wide and
linked together like beads on a string. UCLA's Schopf has
identified 11 species of a type of cyanobacteria (blue-green algae -
these being photosynthetic creatures producing oxygen) in 3.5 billion
year-old (Benton, 1993) rocks from Western Australia (Time No. 41,
1993). Rocks as old as 3.8 billion years from Greenland also show
evidence of early life forms. Today's species composition has
thus taken over three and a half billion years to evolve (Levington,
1992) and possibly as much as 3.9 billion years (Wilson, 1992). This is
only 390 pages into our "book".
Between 4 and 2.5 Billion years ago volcanic activity was so
intense that larger continents could not form. Life only
established when a semblance of stability prevailed! Volcanic activity,
released gases, oxidising iron and removing oxygen from the atmosphere.
An unusually beautiful world this must have been. Without oxygen, the
sky would have been pink and the oceans brown (Sepkosli, 1993), but
without human eyes, there was no creature to appreciate this beauty!
Lifeless continents would break up and change continually, subject to
incredible volcanic forces. By two billion years ago (200 pages), much
radioactivity had diminished and the world had cooled considerably.
Fossil stromatolites found in Western Australia are strange bacterial communities layered on top of one another, comprised mostly of cyanobacteria. Many such deposits have been found around the world and living colonies still flourish in Western Australia, Florida and other parts of the world. Scientists study these to get some idea of these early life forms that were abundant between two billion years ago and the start of the Cambrian Period (Sepkoski, 1993) (in Gould). Stromatolites as old as 3.6 billion years have been found (Orgel, 1994). They were the dominant life form in tropical oceans from 1.5 billion to 680 Mya ago. This microbial community forms felt-like mats on top of shallow water sediments. A secreted gel fastens them to the substrate and protects them from dangerous U.V. radiation that prevailed then. As sediment adheres to the surface of the stromatolites the community grows upwards, leaving behind a glued substrate and eventually the typical oval structures and even deposits 1 km thick!
From about 560 million years ago, to the start of the [top] Cambrian period 543 million years ago, few fossils have been found. This period, called the Vendian, is characterised by one metre long frond shaped organisms. Some species from this period are precursors of the forms that were to flourish and lead to modern forms. The frond-like forms may have been photosynthetic. Other species were ancestral to cnidarians (jellyfish, sea anemones and sea pens). Dickinsonia , another species from this period is segmented, suggesting that it could be ancestral to roundworms and arthropods (crabs, shrimps) (Nash, 1995). The life forms of this era may then have been at the base of an exponential diversification that led to biology's "Big Bang" in the Cambrian Period.
Scientists are not certain why the massive increase in species diversity that started 543 million years ago (54.3 pages ago in the book) during the Cambrian period has not repeated itself. Within 10 million years, all the lineages of the animal kingdom had evolved (Nash, 1995). No new life forms or "body plans" have evolved since then (Levington, 1992). Significantly, the evolution of multicellular organisation came before the dramatic evolutionary leaps of form and diversity that took place. Multicellular organisation did not arise until there was sufficient oxygen in the atmosphere. A geologically simultaneous emergence of complex multicellular forms occurs in Greenland, China, Siberia and Namibia.
organisms, such as the cyanobacteria of stromatolites, began releasing
oxygen into the atmosphere between 2.2 and 1.8 billion years ago (200
pages of our book) (Sepkoski, 1993). However the atmosphere
contained very little oxygen as a chemical transformation was taking
place on a global scale. This involved all the ocean's exposed, soluble
ferrous iron that was oxidised to ferric oxides and precipitated out of
the water. Organisms at this time were anaerobic, not requiring
oxygen for respiratory metabolism. From 2.8 billion (280 pages) years
to 1.8 billion (180 pages) years ago oxygen levels only increased to 1
percent of the atmosphere. At 1.8 billion years ago the first
eukaryotic organisms had probably appeared. The first cells with nuclei
(eukaryote) are definitely present in one billion year old sedimentary
rocks, or 100 pages into the book! By this time bacteria, algae
(blue-green, red, brown, diatoms, yellow-brown) and possibly fungi had
already evolved (De Zanche & Mietto, 1979) (Sepkoski, 1993). Oxygen
levels still did not rise dramatically possibly due to the oxidation of
dead organic matter in the oceans (Nash, 1995).
Eukaryotes [top] are our ancestors as animals containing cells with a real nucleus enclosed in a nuclear membrane and the genetic material carried on chromosomes (Abercrombie, et al, 1973). These first eukaryotes were single celled organisms. Today, only bacteria and blue-green algae and viruses are not eukaryotes.
Evolution from prokaryotes 3.5 billion years ago into eukaryotes 1.8 to 1.4 billion years ago, must have been a fascinating passage, traces of which we see in our living cells. As oxygen filled the atmosphere, it proved toxic to anaerobic organisms, which perished or retreated into specific oxygen free environments. They live in sediments, piles of dead organic matter and stagnant ponds. The biochemistry of our metabolic machinery still practices this old anaerobic tradition. Linked to this is the more modern aerobic apparatus that evolved within the new climate.
Multicellular life accompanied a rise in oxygen levels at the end of the Vendian period. This oxygen rise is a bit of a mystery. Nash (1995) incorrectly observes that "For oxygen to rise, then, the planet's burden of decaying organic matter had to decline." Natural carbon is found in two isotopes called carbon 12 and carbon 13. Algae take up carbon 12 during photosynthesis. For about two billion years, the ratio of carbon 12 to carbon 13 in limestone remained fairly constant. At the end of the Vendian period, there is then a rapid increase in the proportion of carbon 13, showing the removal of organic carbon from the oceans. However, the belief that organic carbon prevented an oxygen increase assumes the presence of aerobic organisms, but the biochemistry of our cells and bacteria show that early organisms were anaerobic. Organic carbon in the ocean could not have prevented an oxygen increase as there were few organisms to use oxygen! Mason (1992) noted that the Earth's temperature has been restricted to the liquid range of water for at least four billion years, . Up to about 3.8 billion years ago, a chemical reaction between aqueous bicarbonate and silicate deposited carbonate sediments. Next, photosynthetic organisms reduced dissolved carbon dioxide, releasing oxygen. Photosynthetic fixation of atmospheric carbon dioxide results in organic substances higher in carbon 12 than carbon 13.
While oxygen levels rose, a nucleus with DNA evolved, enabling the construction of more complex physical structures than bacteria. Life forms also united. Primitive aerobic mitochondria and photosynthetic chloroplasts joined larger, primitive archaebacteria cells in a symbiosis that eventually lead to the animal and plant forms of today (Whitfield, 1993). Living, oxygen-forming bacteria have a similar structure to mitochondria, and chloroplasts share many common features with prochloroplasts. Mitochondria and chloroplasts even have their own primitive DNA rings. In animals, mitochondria are inherited from the mother! As the mitochondria use oxygen, they must have evolved in an oxygen-rich environment.
Sexual reproduction coincided with the evolution of a nucleus and DNA. A cell nucleus is the great difference between our cells and bacteria. The nucleus enabled the production of more complex proteins than bacteria. It opened the door to great versatility, complexity and plasticity of form. This new feature on the evolutionary scene set the stage for the explosion of multicellular forms that occurred 700 million years later! Eukaryotic cells also entered a phase of evolution of the nucleus, a process reflected in genes, called Hox genes, that control embryonic development (Nash, 1995). Ancient life forms, such as jellyfish, only have three Hox genes, flatworms have four, fruit flies have eight, and an ancient primitive chordate, Branchiostoma sp . (Amphioxus) has 10.
Experiments with single celled green algae that have an unusual complexity and size (up to 5 cm), with a base, stem and cap, have shown that the nucleus controls form. The nucleus is found at the base. One species, Acetabularia crenulata has a mop-like cap, and another, A. mediterranea has a flower-like cap. The bases of both, containing the nucleus, are root-like. When they graft one stem onto the base of the other species, the nucleus in the base determines the type of cap that grows (Beck, 1991).
Today, three separate [top] multicellular groups persist (plants, animals, fungi), while about 20 "experiments" are extinct! As described later under the section on genetics, eukaryotic sexual reproduction contributed significantly to the ability to produce different forms by generating variations. This feature of a nucleus, paired chromosomes and sexual reproduction, increased the rate of evolution and the response to the forces of natural selection. Sexual reproduction, with its mixing of genes from both parents also allowed the elimination of mutations through the testing in life of offspring produced. A trend is found from a single cell type in prokaryotic bacteria, to about eleven cell types in primitive jellyfish and about 200 types of cells in mammals.
By 600 million years ago (60 pages into our book), various animal
forms similar to jellyfish, annelid worms and arthropods
(crustacean-like) existed. In the Paleozoic era, between 580 and 560
million years ago, several groups of animals appeared, all without hard
parts such as shells or bones (Sepkoski, 1993). Much of this ancient
life, called the Ediacaran fauna, is not related to modern animal
phyla, "experiments" that did not persist. Five hundred and forty
million years ago (54 pages), an explosive diversification of animal
forms, with an increase in size took place. A faunal assemblage, known
simply as "small shelly fossils" (SSFs) is found at the bottom (more
than 550 Mya) of this phase of diversification world-wide. It contains
some experiments that originated in the Ediacaran, such as three-part
symmetry, but not persisting today.
By 550 to 540 Mya (55 pages), [top] oxygen levels had attained a level near to the current 21 percent of the atmosphere. This level of oxygen was necessary for large, active animals to evolve. Such animals need aerobic respiration and a rich supply of oxygen (Wilson, 1992). Photosynthetic micro-organism had paved the way for more complex forms of life through their effect upon the global atmosphere! Every phylum that exists today, and many modern classes and orders appeared in the fossil record in a short few million years over this period - the Cambrian explosion.
Trilobites were the most successful creatures of the Cambrian period. A variety of bizarre creatures, mostly arthropods, also flourished during this time. The Burgess Shale in British Colombia, Canada, (520 Mya), is one of the best records of this time. Other deposits exist in China, Greenland and elsewhere.
A significant emergence at this time was predators. The diversity of life forms reflected a complex ecosystem. Stalked suspension feeders swayed in the ocean currents, shelly and spiny grazers devoured bacteria and algae off the sea floor, worms burrowed through mud and predators and scavengers scuttling around. A warlike swimming creature, Pikaia , probably belonged to the group that produced our phylum, the chordates, as it has similar V-shaped bundles of muscles along its flanks. This is a feature found in all chordates and a typical phase in mammalian embryological development. Another feature of chordates, the notochord that supports the dorsal nerve column running from head to tail, was also present. Creatures like this eventually evolved into vertebrates.
It took about 30 million years (Cambrian to Ordovician) to evolve from a primitive chordate into the most primitive vertebrate fish. Astraspis (Benton, 1993) were a heavily armoured agnathan or jawless fish 10 cm long. Its jawless mouth sucked in water and detritus to get food. A few species of jawless armoured fish have been found in deposits from the late Silurian period. During the Devonian period (408 to 360 Mya) they became quite diverse. With the evolution of jaws they declined, but there are living representatives in lampreys and hagfish.
No land plants had emerged by this time, but by 500 million years ago (50 pages), a strong [top] ozone layer existed, protecting potential emergent plants from lethal short-wave radiation. Land plants had evolved from green algae (Sebkoski, 1993) by 450 million years ago (Ordovician period; 45 pages ago). Early adaptations were a thick coat to prevent dehydration, breathing pores (stomata) and specialised cells (xylem) to conduct water. Propagation was by hardy spores. Roots systems evolved later. Terrestrial plants have thus only been around for about one tenth of the age of the earth! The first forms of land plant (Rhyniophytes, which evolved into Trimerophytes) were extinct by the end of the Devonian period, replaced by more competitive forms. Horsetails up to 15m tall, clubmosses up to 40m tall and ferns of up to 15m high, evolved from these plants and dominated the Carboniferous period (Benton, 1993). These persisted until the late Devonian period, 360 Mya.
By 400 million years (40 pages) ago, spiders, mites, snails, scorpions, centipedes, insects and many other arthropods thrived in large numbers on the land, thriving upon the diversifying plant forms. These creatures of the forest could be unusually large by our standards. Dragonflies were the size of seagulls and giant millipedes were 2m long! The oldest [top] amphibian fossil found to date, Hynerpeton bassetti , is about 365 million years old (late Devonian) (Science 1994), (Benton, 1993). It lived in tropical muddy marshland and represented one of the earliest terrestrial vertebrates. These animals, moving onto land, encountered plentiful oxygen, insects and plant material.
These amphibians looked more like primitive fish with legs than our modern frog representatives. Ichthyostega lived in marshy areas in Greenland during the late Devonian Period. The head was very similar to the rhipidistian fish, Eusthenopteron . Its 1m long body was streamlined like a fish, retaining a deep tail with fins. As a partly aquatic animal, it breathed air. A strong backbone and ribs suited support and movement on land. Its pectoral girdle is close to the head from which it evolved. On land, it must have moved slowly due to its heavy head and robust, seven toed limbs.
By 350 to 400 (35 to 40 pages) million years ago, ocean life was not so alien and sharks already looked like they do today. Only 70 to 100 million years ago (7 to 10 pages) ago 13 metres long Loch Ness type monsters, Elasmosaurus , still flourished and dinosaurs still roamed the earth!
Coal forests began to replace the colonising plants about 340 million years (34 pages) ago, and were replaced by other forms 240 million years ago (24 pages). During this time amphibians spread and diversified, establishing the main lineages for later tetrapod evolution. The first reptiles with cleidoic ("closed") eggs emerged about 350 million years ago, but most fossil finds date from about 310 Mya onwards. Hylonomus , a 20 centimetre long lizard, fed on insects in mid Carboniferous forests. Shelled eggs freed these creatures from the need for water for reproduction. From the reptiles of the Carboniferous period, two major lineages and a third minor lineage evolved. Survivors of the minor group are tortoises and turtles. Lizards, snakes and crocodiles represent one major lineage. Somewhere and time, from this lineage, birds also evolved. The other major lineage evolved into mammals about 220 million years ago (Gore, 1989). Skull features are used to easily identify these three groupings. Dinosaurs and other extinct groups also had cleidoic eggs so evolved from the same common ancestor that originated the cleidoic egg.
Ferns, conifers, cycads and cycadeoids filled another transition period, replaced, about 100 million years ago (10 pages) by the forerunners of flowering plants that dominate the earth today. Our so familiar flowering plants are new additions to the earth.
Where the ancestor of humanity was at this time, we can only guess. Fossils from about 190 million years (19 pages) ago, the late Triassic period were already mammals, but very small and mouse-like. True placental mammals arose about 130 to 140 million years ago (13 to 14 pages) (one page = 10 million years) ago and formed part of the only surviving mammal line, the pantotheres, with the marsupials. Marsupials were originally dominant, during the Cretaceous period.
A ten kilometre wide asteroid collided with the earth about 65 million years ago, leaving behind a telltale rare iridium element clay layer, today evident in Spain, Denmark and New Zealand (Gore, 1989). Iridium is common in meteorites, but rare on earth. This impact would have caused massive temporary climatic changes as a dust cloud blanketed the world. Sooty carbon remains found with the iridium suggest that there were widespread fires. Hurricane strength winds, earthquakes and volcanic eruptions would have followed the meteor impact. The earth probably became very cold. This would have stimulated instinctive hibernation in small mammal creatures.
With the sudden extinction of the dinosaurs 65 million years (6.5 pages) ago, [top] mammals flourished and diversified. Within 10 million years mammals as different as whales and bats had evolved! The first primates, the mammal group giving rise to humanity, appeared fifty to sixty million years ago. This is only five to six pages into our book! Pongids, the lineage of apes such as chimpanzees, gorillas and orangutans appeared two to three pages or 20 to 30 million years ago (Oligocene) (De Zanche & Mietto, 1979).
Such a 450 page book may have 50 lines per page. Each line then represents 200,000 years, the estimated maximum period of existence of Homo sapiens sapiens . Early hominids (or the hominid family) appeared 7.5 million years ago or 38 lines into the first page of the book (Leakey & Lewin, 1992). A hominid is a member of the human family, be it modern humans or the earliest ancestral forms that we find in the fossil record. All hominids share the inherited character of bipedalism (upright walking on two feet). Australopithecus is the genus of the most primitive fossils considered a part of the human lineage. Next to evolve was Homo erectus and then Homo sapiens .
Molecular evidence suggests that [top] chimpanzees and humans separated from a common ancestor about 7.5 million years ago and humans and gorillas 9.5 million years ago (48 lines or almost one page) (Leakey & Lewin, 1992). Other researchers studying molecular evidence (immunological assays, protein electrophoresis, amino acid sequencing, DNA-DNA hybridisation, DNA restriction-site analyses and nucleotide sequencing from mtDNA and several nuclear genes and non coding regions) claim that humans separated from the ape lineage as recently as 4 to 8 million years ago (Avise, 1994). Our early ancestor resembled us in being bipedal creatures (walking upright). Right now, there is a lack of fossil evidence between this ancestor and five million years ago (20 lines) (see Human Evolution section). A. afarensis appeared roughly 20 lines ago (four million years) and existed for less than 1.5 million years. Australopithecus africanus (Dart, 1925), is found from 15 lines ago and appeared to exist for 750,000 years, disappearing about 2.5 million years ago (Groves, 1994). A more recent species, A. boisei ( Paranthropus boisei ) ( Zinjanthropus boisei (Leakey, 1959)) existed with the Homo species, but all australopithecine species were extinct by one million years (five lines) ago.
The earliest stone tools appear in the record about 2.5 million years ago or 12 lines into the first page of recent time (Leakey & Lewin, 1992). Homo habilis made pebble tools about 1.8 million years (nine or ten lines) ago and represents the first Homo species. Tools and a jaw bone fragment dated at 1.9 million years old have been found in central China, showing an early and wide distribution for Homo habilis .
Stone tools mark the beginning of the Palaeolithic Period or Old Stone Age, which continues until 10,000 years ago. BIPEDAL APES had thus been around for a long time before Homo sp. evolved from them! In the biblical story of Cain and Able is a hint as to the fate of these ancient relatives of ours. In the fossil record there are many human-like species that diverge from the ancestral line that led to humans. The fact that they are all extinct hints that their close relatives drove them to extinction, just as Cain killed Abel. The Biblical story may be a metaphor that reflects what is found in the fossil record.
The "harbinger of humanity" is considered [top] Homo erectus . This creature existed 1.6 to 1.7 million years ago or eight lines into our book of life. Leakey and Lewin (1992), in their book "Origins reconsidered", observed that "Everything earlier than Homo erectus was more ape-like (except the short-lived, somewhat enigmatic Homo habilis ). Everything after Homo erectus was distinctly human-like, in behaviour as well as form. The beginnings of a hunting-and-gathering way of life came with Homo erectu s. For the first time stone tools had the impression of standardisation, the imposition of a mental template; fire was harnessed for the first time; for the first time hominids expanded beyond the African continent. . . . If we are to understand the origin of humanity, we have to understand Homo erectus , its anatomy, its biology, its behaviour" (Leakey & Lewin, 1992). Homo erectus also marks the time of substantial brain volume increase. Archaic Homo fossils with fairly large brains but with heavy brow ridges like H. erectus appear in the fossil records from about 300,000 years ago (Dawkins, 1993), while truly human fossils appear 100,000 years ago.
Now, if we take there to be 50 letters per line in our "Book of Life", each letter on the line represents 4000 years. Jesus appeared on Earth only half a letter ago! About 100,000 years ago, humanity was confined to Africa and perhaps the warmer parts of Europe and Asia. At around 50,000 (12.5 letters) years ago, Australia and New Guinea were colonised. Humans occupied Siberia only five letters ago (20,000 years), most of North and South America, only three letters ago (11,000 years ago), Asia 53,000 years ago (Reader, 1988). They occupied some world's most remote islands only recently, within half a letter ago (Diamond, 1991). Hunting skills and stone tools have been with us for most of this time, polished stone tools and agriculture (farming and herding) appeared only 2.5 letters ago (10,000 years) at the beginning of the Neolithic period. Crop cultivation with animal herding seems to have originated in the Near East, with wheat and barley in use 10,000 years ago and the full integration with animal herding found by 8,000 years ago (Diamond, 1991). Metal tools, the beginnings of metallurgy appeared only 1.5 letters ago (6,000 years) (Diamond, 1991). There is no record of wheeled vehicles before 5300 years ago, while people domesticated and rode horses in the steppes just north of the black sea by at least 6000 years ago (1.5 letters).
When ancient Egypt [top] flourished from about 5000 years ago, many inventions and luxuries of today were in use. Kings and queens adorned themselves with golden jewellery, boats paddled up and down the Nile, scribes kept written records, people ate foods such as onions, cucumbers, beans, lentils, and lettuce, and made bread and beer from wheat and barley (Time-Life Books, 1992). Farmers tended vineyards and the rich ate beef and pork. Food was spiced with garlic, cumin, coriander, parsley and fenugreek. Cakes and pastries were sweetened with honey, dates and figs. Musicians played harps while singers entertained the rich. Fishers hunted for fish and waterfowl on the Nile. Designers made boats constructed in kits for later assembly. Furniture included very modern looking tables, soft chairs and beds and footstools. Mothers kissed and cuddled their children. Women had cosmetic boxes with combs and perfumes, wore wigs of real hair and fine elbow-length gloves, and razors were used for shaving and tweezers for plucking unwanted hair. Board games occupied leisure time and artists covered walls with colourful paintings. Horses hauled chariots and cattle pulled ploughs. Boomerangs, bows and arrows and spears were weapons for war or tools for hunting.
Our necessities and luxuries are little different from those of ancient Egypt so long ago. Yet, the development and changes that have occurred during the last few moments in the time of life have been explosive beyond comparison or comprehension and we take it all for granted. The difference lies, not in what we value, but in the technology that we use to change the very nature that we depend upon.
A letter in our "Book of Time" has to be divided twenty times to represent 200 years! Now recall the PROGRESS, INVENTIONS and DAMAGE of the past 200 years. Even compared with a page of the "Book of Time", it is a moment. The dinosaurs became extinct six and a half pages (sixty five million years) ago, each line being 200,000 years and flourished for sixteen and a half pages prior to this! Compare this with a momentary 1/20th of a letter representing the last 200 years that is our glory! Motor vehicles have been in use on earth for 1/40th of a letter of the 460 "Book of Time" with fifty lines per page and fifty letters per line! This makes modern technology a real freak of nature. Freaks do not usually persist. Time favours nature's way, hence the Tao. Natural laws of the universe persist.
The last 200 years has been a period of enormous change. We have created our civilisation's main technological inventions within only 1/20th of a letter of the "Book of Time". Looked at in the light of previous evolution, this is out of the ordinary, not the usual pattern, something unique and in this way a freak of nature. For us it seems normal.
Our failing, as far as human intelligence is concerned, is that we take such modern technology for granted and have not yet comprehended our brief glory via unique innovation. "Mankind now lives, smugly, in a century of such unsuperstitious confidence. It embraces the dangerous illusion that the well-explained way of the recent world is the way things always are" (Economist, 1993). We ride upon an energy joyride powered by fossil fuels, with no regard for our destination. "An understanding of human origins tells us that Homo sapiens is a part of the natural world here on Earth, one species among many. But do we have the intelligence to comprehend the impact of what we do as a species on the rest of the species around us"(Leakey & Lewin, 1992).
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