1. Introduction
This post tries to explain how the genesis and evolution of human civilization depended on our planet having first gone through an orchestrated sequence of astronomical, geological and biological processes. This is over and above the cosmic fine tuning needed to allow pre-human life to exist. (Some of Part 4 overlaps with Part 3 but re-presents the material from a different perspective.)
2. Defining civilization
Civilization I am defining as a way of living which, depending on the values and beliefs adopted confers benefits on its people through improving technology, communications and transport, increasing security against internal or foreign attacks on life and property, growing agricultural efficiency, development of medicine and continually evolving knowledge of the world and how humanity relates to the Creator.
3. Origin
4. Cosmic time window
The universe started 13.73 billion years ago, expanding steadily after the first fraction of a second (the Big Bang). After 7 billion years it started to accelerate and appears set to continue this acceleration indefinitely. Before the stars were as far apart as they are now an observer anywhere in the universe would be blinded by a perpetually bright sky, unable to observe or deduce the nature of the cosmos, even if the atmosphere was clear. Only very recently in cosmic terms have the stars been sufficiently far apart to permit peering back to the moment of creation.
Conversely, in future the expansion will be so fast that observers would see only relatively nearby objects, and again would be unable to witness the Big Bang creation event.
Therefore we appear to be in a time window of a few million years when it is possible to deduce the history and nature of our universe.
5. Solar time window
The Sun, a yellow dwarf star with a lifetime of about 10 billion years, emitted radiation at a subdued level as it entered into a relatively stable period of solar flare activity, beginning 50,000 years ago and likely to continue for another 50,000. This is based on the assumption that it will follow the pattern of similar stars observed at different stages of evolution over billions of years i.e. by monitoring a given type of star at different distances, you can see what that type of star was doing at different times in the past.
Even with the Sun in a relatively calm phase it still emits lethal streams of particles. At the same time our planet is irradiated with life destroying cosmic rays from supernovae, gamma-ray bursts and the supermassive black hole at the centre of our galaxy. Providentially, at this stage of galactic evolution and in our present position in the galaxy, such irradiation is well below normal. Nevertheless it would still have prevented human life without the magnetic shield which surrounds our planet and which was in place in time to protect humans when they first appeared, as it does now.
UV rays from the Sun also would have prevented human life had it not been for the ozone layer, around 25 km high, the triatomic oxygen molecules of which absorb much of the incoming ultraviolet, rendering it benevolent, e.g. by stimulating the production of vitamin D, rather than doing harm to the body.
6. Clear skies and celestial order
By the time human beings (homo sapiens sapiens) appeared the Earth’s rotation period had slowed down from just a few hours to the 24 hours we know today. It is still gradually slowing down because of the Moon’s influence and at some time in the far future it will be too slow for habitability because of the effect on climate. Even another half hour or so would cause too much difference between day and night temperature.
Initially the sky was opaque. Then by the time human beings appeared it had cleared over much of the globe to permit a good view of the Sun, Moon, planets, stars and comets. The Moon and Sun in particular would have excited the curiosity of early man by their cyclic order, phases and eclipses, as well as by the way their movements are related to tides and seasons. The stars, Milky Way and planets would also have been sources of wonder. The ordered behaviour of the heavens and the correlation of this to the seasons would have led many to believe in a hidden order throughout the living world.
7. Preparation for agriculture and its consequences
Cultivation of land for crops was necessary for the generation of food surpluses which allowed resources to be spent on discovery, music, art, literature, drama, public buildings, a civil service , a judiciary, a religious order and armies for protection, conquest and subjugation.
The first civilization, the Sumerians in Mesopotamia, was made possible by the large areas of very fertile soil deposited when the Euphrates and Tigris flooded. This soil had been formed over millions of years by the weathering, erosion and crushing of rocks coupled with the action of bacteria. The rocks had a composition beneficial to farming because of the minerals brought to the surface of the earth by tectonic activity, itself a consequence of the heat from radioactive U and Th generated in supernovae and somehow transported into the vicinity of the Earth as it formed, 4.4 billion years ago.
The fertility of soil greatly depends on the fixation of nitrogen from the atmosphere, a process which depends on lightning for energy and on the presence of bacteria or blue green algae. Again, the possibility of civilization depends on the most unlikely of causes. No lightning and bacteria would mean no Sistine Chapel.
8. Preparation for construction and technology
Wood, metallic ores and clay were essential to allow the construction of houses, public buildings, bridges, roads, temples, ploughs, carts , ships and, within a short span of geological time, aircraft, spaceships, engines, computers, communication technology and much else. The wood obviously came from forests, the clay was another form of soil (see above) while the metallic ores were made available through plate tectonic activity which prevented heavy metals like iron sinking through the magma towards the centre of the planet. Certain metals, e.g. gold and titanium, were also delivered by meteorites.
Apart from its use in cooking, keeping warm and providing light, fire was essential for smelting, refining and materials processing, all necessary for the development of a civilization. Fire depended very much on the atmosphere having the right amount of oxygen for controllable combustion and appears to have been the result of sophisticated biochemical 1feedback over billions of years.
9. Preparation for water transport and motive power
Apart from the provision of fish etc. for food the rivers, lakes and oceans which cross and connect the continents were and still are needed for the transport of heavy loads up to very long distances, making trade and industrial specialization possible on a global scale
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Fast flowing rivers were also used for pumps and mills. Even today they are used for hydroelectric schemes . All expanses of water were used for recreation right from the earliest civilizations.
10. Animals
Certain domesticated animals were crucial to early societies for motive power, transport, farming, hunting, hygiene by scavenging in human settlements, sport and companionship. These included, and still include: oxen, sheep, goats, horses, donkeys, elephants, birds of prey and dogs. Such animals had a genetic structure lending itself to varying degrees of selective breeding. Parts of the world where they had been hunted to extinction (e.g. parts of the Americas) or were not present initially, were not able to progress beyond the Neolithic stage.
Birds of prey must have inspired the concept of humans being able to fly, a vision which ultimately led to balloons, aircraft and spaceships. In fact without birds it is difficult to imagine how anyone would even have dreamed of flying.
11. A precious planet indeed
So overall it looks as though civilization was made possible by a unique set of circumstances and that the Earth is indeed a precious planet.
Whether we are the only conscious beings in the created order and ones having a sense of love, truth, justice and beauty as well as relentless curiosity and the power of reason we are unlikely ever to know. If there were no creator, i.e. if all the above is a product of blind chance, the probability of sentient beings elsewhere is, for all practical and rational purposes, zero.
Conversely, if there is a God (and all rational and reasonable argument points in that direction) no being in his or her mortal state can define God’s ultimate purpose, one which could include sentient beings on another precious planet. Personally, it would not bother me if the humans are the only sentient life in the universe. It need not make us feel lonely- just alone with God.
Acknowledgements
These posts in the Our Precious Planet series were inspired largely by Hugh Ross’s Why the universe is the way it is. Other sources include Paul Davies’s The Goldilocks enigma, Peter Douglas Ward’s Rare earth, and Rodney Holder’s Big Bang Big God. I also made use of Wikipedia and popular science sources.
John Sears
Author, 2077:Knights of Peace
Links to all 4 parts of Our Precious Planet and some related links are given here.
