New theory of the geological history of Earth.
It is known that the Earth was created about 4.5 billion years ago (more precisely from 4.6 till 4.45 billion years). Scientists divide the geological history of Earth into some main eras: Archaeus, Proterozoic, Paleozoic, Mesozoic, Cenozoic. Such division does not give possibility to answer the question: at what stage of its development is the Earth situated now? The postulated eras have not the same length in the time. In difference to the accepted now, our classification divides the geological history into cycles and periods, which have equal time length. For the simplicity we accept the initial date of creation of Earth and Sun ca. 4.555(5)… billion years. Then we can postulate the following cycles:
I.4.555(5)…-3.555(5)… billion years.
II.3.555(5)…-2.555(5)... billion years.
III.2.555(5)…-1.555(5)… billion years.
IV.1.555(5)…-0.555(5)… billion years.
V. 0.555(5)… billion years – till modern time.
For the simplicity, first four cycles can be divided into two sub-cycles half a billion years each. The division of every cycle into 9 periods 111,1(1)… million years each is more precise.
Four cycles make together so called pre-Caembrium or the most ancient history of the Earth. The last, 5th cycle made now a bit more than a half of its development. It can also be divided into five periods 111,1(1)… billion years each. It is possible that after the end of the ice time the new, 6th period began, which corresponds to Holocene, begun 11.5 thousand years ago. Metaphorically 100 million years correspond to one year, i.e. the Earth is now about 45-46 years old (if we imagine it as a living creature, as already the ancient thought). Let us look how our division corresponds to the reconstructed in the present time geological history.
1 part of the first cycle corresponds to so called “pre-geological” stage of the planet’s existence, dated
4.5-4.0 billion years. It is so called “accretion period”, which lasted 100 billion years and corresponds to the uterine development. In this time core, mantle, sub-divided into lower and upper, and possibly the initial crust, which consisted from basalt, were created. Earth damaged from the strongest meteorite bombarding, which caused its warming-up, creation of the initial atmosphere, hydrosphere, which were different from modern ones, formation of the magmatic ocean in the upper part of the mantle. In the same time the liquid core of Earth and the first basaltic Earth mantle were created. Probably the first atmosphere had strong hothouse effect. Proto-atmosphere consisted from H2O, CO2, CH4, CO, H2S, SO2, HCl and some other gases and combinations, which were partly dissolved in the initial chloride and sulphateless hydrosphere, which had to be in equilibrium with atmosphere. The oldest fragment materials circones (Western Australia) are dated with
4.3-4.2 billion years.
2nd part of the first cycle corresponds to the early Archaeus (4.0-3.5 billion years). In this time Earth had almost all spheres, besides the inside core - the outside core, mantle, crust, atmosphere and hydrosphere. The initial atmosphere could be like Venerian, temperature was much more than the modern one. Presence of hydrosphere is confirmed with the aquatic presence of quartzites in the oldest complex of Isua in Greenland. In it graphite is present, where the content of isotopes of 13С to 12С is almost the same like in the modern organic remnants. At the expense of the melting of the initial basaltic crust with participance of the fluids, which came from mantle, the siale isles – proto-continents appeared, raising over the still very shallow water ocean. They were made from the “grey gneises” – granitoides, which differed from the later “normal” granites with prevalence of natrium over calium in its content. At the expense of washing out of this dry land the first sedimental fragment rocks were created, discovered in Greenland and Canada (age 4-3.8 billion years). 3.8 billion years ago the first procariotes (microphossils) were created. In the same time the meteorite bombarding ends and the Earth satellite Moon is created. In the whole this cycle corresponds to the physical plane. The geological age of Earth corresponds to the age of child till ten years.
The first part corresponds to the middle Archaeus ((3.5-3.0 billion years), the second – to the late Archaeus (3.0-2.5 billion years). In the whole this cycle corresponds to the aethereal plane. Geological age of the Earth corresponds to the teen-ager till 20 years.
Main geological events of this epoch:
3.5 billion – plausible remnants of the magnetic field, which did not differ from the modern.
3.2 billion – begin of the creation of the ripe continental crust.
3.0 billion – on the Earth the mechanism of lithosphere plates began to function.
In the end of Archaeus (2.7-2.5 billion years) stabilization of the continental crust began.
In this time the organic life is created. Its remnants are known in the old rocks of the Pilbara bloc (3.5-3.4 billion years) in the Western Australia, where remnants of the life activity of blue-green algae –cyanophites (stromatolithes and oncolithes) are found. The microscopic creations – shells of the one cell cyanophites (acritarches) and contractions from carbonates (katagraphias) are found. The first living creatures were bacteria, changing inorganic combinations into organic ones, using the sun light. Bacteria decomposed hydrogen sulphide, educing sulphur. Blue-green algae began to decompose water, educing oxygen, and the ozone layer, which appeared in the upper layers of atmosphere, guarded organisms from the deadly ultraviolet radiation, therefore they could exist already not only in the water, but also on the dry land. In the rocks useful fossils are created. Among them there are iron, gold, copper, lead and other metals and graphites.
This cycle corresponds to the early Proterozoicum (2.5-1.65 billion years). In the whole it corresponds to the lower astral plane. In comparison with the human life it can be compared with the youth from 20 till 30 years.
Main geological events of the epoch:
2.5 billion years – creation of the supercontinent Pangaea-0, which contained from 60% till 80% of the crust volume of modern continent. At the other side of the planet the even greater ocean – Panthalassa had to oppose it; probably, it was created because of the fall of giant meteorite. The cover freezing (Guron) takes place.
2.2 billion years – Pangaea-0 began to disintegrate with creation of basins with the crust of oceanic type.
2.0 billion years – in the atmosphere the presence of oxygen can be detected. The moving zones finish their development.
1.8 billion years – creation of Pangaea-I (Rodinia).
In the course of early Proterozoicum the developmentof organic world was expressed in the broad expansion of blue-green algae; the products of their live activity as lime films composed stromatolite buildings, which reached the length of hundreds meters in some places (first stromatolites appeared in the late Archaeus). The photosynthesis activity of theses algae caused the changing of atmosphere composition with the increasing of oxygene in it, which stimulated the further flourishing of organic world in its turn. It is not excluded that the educed oxygene, reacting with the iron, dissolved in the water, promoted the precipitation of iron oxides, in the result of which the thick layers of the stripe iron quartzites – jaspilites were formed. The procariote organisms – bacteria existed too. Early Proterozoicum was a famous epoch of iron ore accumulation. The gold-uranium-pyrite conglomerates, copper ores, as well as diamond and gold fields are formed (modern Africa).
This cycle corresponds to the late Proterozoicum (Riphaeus) and Vend (1.650-540 million years). In the whole it corresponds to the upper astral plane. In comparison with the human life it corresponds to the period from 30 till 40 years.
The 1st part corresponds to the lower and middle Riphaeus (1.650-1.350, 1.350-1.000 billion years),the 2nd part – upper Riphaeus and Vend. The main events of the epoch:
1.4 billion years – emergence of the first eucariota (algae).
1.4-1.35 billion years – development of volcano plutonic zones, outbreak of granitoide magnetism.
0.8 billion years – disintegration of Pangaea-I; emergence of multicellar plants (algae);
0.67 billion years – emergence of the Vend skeletonless fauna (Ediacaria);
0.57 billion years – emergence of the skeletonless fauna of invertebrates.
This cycle corresponds to the Phanerozoic epoch. In the whole it corresponds to the lower mental plane (animal world). In comparison with the human life it corresponds to the period from 40 from 46 years.
As we already mentioned before, the last, Vth cycle went through a bit than a half of its development. One can divide it into five periods 111,1(1)… million years each. Probably, after the end of the last ice time a new, 6th period began, which corresponds to Holocene, begun only 11.500 years ago.
555,5 (5)… – 444,4(4)… million years.
This period corresponds clearly enough to geological Caembrium (542-488.3 million years) and Ordovician (488.3 – 443.7 billion years).
Main events of this period:
0.56 billion years – quantity of oxygene in the atmosphere reaches 1/3 from normal.
0.46 billion years – first terrestrian plants appear.
0.45-0.43 billion years – first dying out of organisms.
Материки концентрировались преимущественно вблизи экватора, что и способствовало установлению теплого климата, вероятно, вместе с усилением эксплозивного вулканизма.
The main event of the Caembrium was emergence and rapid flourishing of the varied fauna of invertebrates, which had a mineral skeleton, emergence and domination of trilobites. It appeared at the background of the domination of warm climate and broad spreading of the epicontinental seas. To the begin of the period megacontinent Gondwana was formed and future northern continents – Laurentia, Baltia, Siberia, Sinokorea were separated with the oceans, which continued to expand in Caembrium: in the present time their crust is represented with ophiolithes.
Main features of the Ordovician period:
-preservation of Gondwana unity and the square of other continents with contemporary maximal expansion of intercontinental oceans (Japetus, Paleothetis, Paleoasiatic) in the middle of period; in the late Ordovician the Takon orogenesis appears, which causes the essential changes in the inside structure of some moving zones, especially of the Paleoasiatic ocean;
-domination of the warm climate in the course of early and middle Ordovician, then rapid cooling and emergence of the cover freezing in Gondwana and its periphery in the connection with moving of Gondwana into the polar region of South ocean;
-further development of organic world with possible emergence of terrestrian plants. Emergence of sea-urchins. Graptolithes played an important part in the Ordovician. Molluscs and jawless fishlike organisms were spreaded broadly in Ordovician.
444,4(4)… – 333,3(3)… million years.
This period corresponds to Silurian (443.7 - 416 million years), Devon (416-359.2 million years) and first two layers of the Carbon period (Turnean – 359.2-345.3 million years and Vizean – 345.3- 326.4 million years).
0.42 billion years – emergence of fishes – first vertebrates.
Relatively small Silurian period looks like transitory between thalassocratic (i.e. with predominance) and geocratic (i.e. with predominance of dry land) Devonian. In the begin of period on the west of Gondwana glaciers, inherited from Silurian, were still preserved, but then climate became more and more warm. Silurian period was remarkable with the closing of Japetus ocean, Tornquist sea and reduction of square of central and eastern Paleothetis and Paleojapetic ocean and ended with epoch of the mighty mountain creation, plication, granite magmatism and regional metamorphism. Although in the composition of Silurian biota the same invertebrates like in Caembrium and Ordovician prevailed, especially graptolithes, the emergence of vertebrates, among them the first fishes, and the first terrestrian plants – lycopodia together with mosses and mushrooms, inhabiting the dry land, is remarkable.
Devonian period was one of the turning-points of the Earth history. It closed early and began late Paleozoicum. Frontier of Silurian and Devon corresponds with culmination of Caledonian orogenesis, which created North Atlantic zone of caledonides, united Laurentia and Baltia and created new megacontinent Laurentia. It was a first step to the creation of Pangaea-II. In the course of Devon period the climate was warm and even hot, arid or wet. In the seas many crustacean, fishes, ammonoideae emerged, on the dry land – luxuriant plants, including ferns. In the early Devon first wingless insects emerged, in the end – first amphibian were created.
333,3(3)… – 222,2(2)… million years.
Period corresponds to Carbon (359.2-299 million years), Perm (299-251 mln. years) periods of Paleozoicum and lower and middle Trias (251-228 million years).
0.25 billion years – emergence of hymnospermae plants
0.24 billion years – creation of Pangaea-II, mass effusions of basalts.
In the early carbon the warm climate dominated everywhere, seas had broad diffusion. In the second part of Carbon the creation of one Pangaea-II took place because of the collision of the Western Gondwana with Laurussia in the region of south of North America and Western Mediterranean. The giant cover freezing, which encircled Gondwana, was created. The domination of warm and wet climate out of the freezing region created conditions for the luxuriant development of different wood plants and for the creation of vast zone of coal accumulation (possibly, because of the mighty hurricanes). Development of the animal world: amphibia, reptilia and insects were created.
To the begin of Perm in the whole the genesis of Pangaea-II was finished, Baltia, Kazakhstan and Siberia united, one Laurasia was formed. Cover freezing of Gondwana degraded gradually, glacial sediments were succeeded with carboniferous, then with red colour thick layers. The tin (Cornwall, England) and mercury (Nikitovskoye) deposits appeared. In the whole for the Perm period very contrast climatic conditions are typical, it was closed with the extinction of many groups of Paleozoic fauna.
In Trias the existing of one Pangaea-II and one Gondwana as its part ends, but not fully. Warm, even hot climate is preserved. In the begin of the period the organic world has a transitory character from Paleozoicum, but generally it has changes. In the sea the ammonoideae, six beam corals, on the dry land reptilian are created. First dinosaurs emerged.
222,2(2)… – 111,1(1)… million years.
Period corresponds to the upper Trias (228-199.6 million years), Jurassic (199.6-145.5 million)
and lower Cretaceous period till Alb layer (145.5-112 million years).
In the upper Trias rifts in the North Atlantic are opened, first mammals are created.
Jurassic period was characterized with the begin of disintegration of last Pangaea-II, among it Gondwana, and creation of Atlantic and Pacific Ocean – 0.16 billion years. In the end of middle Jura ocean Thetis with its continuation into Central Atlantics and Mexican-Caribic region separated Laurasia from Gondwana fully. In the begin of Jurassic period the early Lamirian orogenesis , manifested in Eatern and South-East Asia, in the end – late Lamirian, manifested in the Pacific circle of moving zones, takes place. In the Jura sediments about 16% of world coal reserves are preserved.In the course of all period climate remained warm and mostly wet. Among the sea fauna ammonites predominated, among the dry land one the domination of dinosaurs began, meanwhile the sea were explored by the big pangolins – plesiosaurs, ikhtiosaurs. In the late Jura the first birds were created. In Early Cretaceous period big foraminipherae – orbitolithes emerge. Gondwana is disintegrated, South Atlantics is created. In the begin of Cretaceous period the late Cimmerian orogenesis takes place.
5 period -111,1(1)... mln. – 11,500 BP.
To this period the Late Cretaceous, Paleogene, Neogene and Quarternary periods belong. The continents took their today´s shape slowly. About 68 million years ago. They have almost today´s shape, but India is an independent continent and Arabia is connected with Africa. Reptiles (Dinosaurs) dominated on the Earth. Flowering plants (angiosperms) diversified during the Cretaceous, but remained a minor contributor to plant biomass and ecosystem function until after the End Cretaceous extinction. The earliest probable grass phytoliths have been found in fossilized dinosaurs dung from the latest Cretaceous, just before 65 million ago. Mammals were also quietly evolving throughout the Cretaceous. The first termite body fossiles also came from the Late Triassic. By the start of the Late Cretaceous (100-90 million years ago) both fossils and molecular clocks agree that some of the main “crown” mammal lineages had already diverged (eutherian or placental mammals had already arisen by 125 million years ago). But the Mesozoic mammals could not challenge the smaller brained dinosaurs for ecological dominance.
65 millions years ago the End Cretaceous extinction, which famously killed off the dinosaurs, took place. It marks the transition from the Mesozoic to the Cenozoic Era. A thin sedimentary layer enriched in the element iridium at the boundary of the Cretaceous and Paleogene periods provides convincing evidence that a massive asteroid (asteroid) hit the planet. The vast volcanic flood basalts – the Deccan traps – erupted over less than a mllion years leading up to the boundary. There is also some evidence of ocean anoxia of the End Cretaceous. The Cretaceous mass extinction impacted land as well as marine life. There were widespread wildfires at the boundary and vegetation was decimated by global deforestation. In the aftermath there was a brief flourishing of fungi feeding on decaying plant material (saprotrophs), then ferns colonized the land. Terrestrial ecosystems than recovered to something approximating their pre-extinction state much faster than marine ecosystems (which took around three million years). Land animals suffered remarkably selective extinctions. Insect diversity had been high beforehand but was still low nearly two million years after, probably because of the temporary loss of plants. Verterbrates that could retreat to the water including amphibians, turtles, snakes, lizards and crocodiles all faired reasonably well. In the air, the last Pterosaurs died out but birds largely survived. All major mammal lineages survived (including egg laying monotremes, marsupials and placentals) although they suffered losses. Cretaceous mammals were generally small in size, comparable to that of rats, and may have burrowed or lived partly in water. In general among land animals, omnivores fared well, whereas pure carnivores or herbivores suffered.
After the End Cretaceous extinction, mammals came to fill many of the ecological niches vacated by the dinosaurs. They increased in the size within one million from the boundary. That was accompanied by striking species diversification in the best preserved continental fossil record from North America. Hovewer, this diversification, in the Paleocene Epoch, was mostly among groups of mammals that have subsequently declined or gone extinct. Rodents may have diverged from other placental mammals in the Paleocene. Grass pollen then starts to appears from about 60 million years ago. Hovewer, the modern orders of placental mammals did not originate until ten million years after the End Cretacous. The three key orders that emerged then were the Primates (to which we belong), the even-toed ungulates (Artiodactyla), and the odd-toed ungulates (Perissodactyla). All these orders appeared in a remarkable time of climatic upheaval called the Paleocene-Eocene Thermal Maximum (“PETM”). It was an interval of rapid global warming 55.8 million years ago. Global temperatures rose roughly 5°C within 20 000 years and remained high for roughly 100 000 years. There was also a major perturbation of the carbon cycle, whic occurred in two steps, each lasting roughly 1000 years and separated by 20 000 years. The trigger may have been a volcanic intrusion into carbon-rich sediments under the North Atlantic. Methane released would have been rapidly oxidized to carbon dioxide, contributing to warming and ocean acidification. Acidification in turn dissolved carbonate sediments in the deep ocean and caused the extinction of many calcareous-shelled organisms living there. It took around 100 000 years for the carbon cycle to recover. During the PETM, the modern orders of mammals appeared within 10 000 years or so of each other in North America, Europe and Asia. Primates were the last of the three orders to arrive roughly 10 000 years into the event. The earliest species were significantly smaller than their immediate descendants. This dwarfism could be due to poor plant food quality in a carbon dioxide rich world. The early part of the PETM was dominated by small leaved plants indicative of a dry climate. Later in the PETM the climate became wetter. The first unequivocal fossil parts of grass plants appear 55 million years ago. The contact between Australia and the Antarctis was lost 56 million years ago.
An overall driver for the spread of grasslands was a cooling and drying of the climate over the last 50 million years, which in turn was probably driven by declining carbon dioxide concentration. The steady trend was interrupted by a relatively rapid cooling and drying of the climate 33.7 mln years ago, which marks the boundary between the Eocene and Oligocene Epochs of the Paleogene Period. This occurred when atmospheric carbon dioxide and temperature passed a critical threshold triggering the rapid growth of large ice sheets on the continent of Antarctica. It in turn triggered the first phase of grassland expansion, at the mid-latitudes became cooler and drier and the first desert grasslands replaced earlier woodland in the Great Plans of North America. The soils undernearth the grasses experienced an increased intensity of silicate weathering, which would have contributed somewhat to declining cron dioxide and global cooling.
The second phase of grassland expansion began around 17 million years ago, early in the Miocene Epoch. Short grasses appeared forming a sod, or natural carpet, with more organic-rich soils beneath them. Such grasslands are effective at chocking out the seedlings of woody plants and promoting the spread of fire; charcoal becomes more abundant in he rock record record at the time. Grazing hoofed mammals (ungulates) expanded with the grasslands, having specially adapted (hypsodont) teeth to grind down the silica-rich grass matter. There was an explosive adaptive radiation of horses and antelope, along with many other mammals adapted to feeding on grasses and living in grasslands. Increased weathering led to increased inputs of phosphorus and silicon to he ocean and increased burial of them in marine sediments, and conceivably contributed to a resumption of climate cooling and Antarctic glaciation. The presence of grass rather than trees would have increased the reflectivity of the land surface, tending to cool the continental interiors and increase their seasonity.
The third phase of grassland expansion occurred late in in the Miocene, beginning around seven million years ago. Tall grasses forming a sod appeared with deep soils under them. They expanded into more humid regions, promoting fire as they displaced forests, again recorded by increased charcoal in the rock record. During this phase, a mecanism of concentration carbon dioxide at the side of carbon fixation within the plant, called “C4 metabolism”, proliferated among the grasses. (C4 plants were already present by about 15 million years ago, but between 7 and 5 years ago they underwent a marked expansion in the tropics). The expansion of these grasses caused another pulse of increased weathering and phosphorus and carbon burial in the ocean.
The pliocene spans 5.3-1.8 million years ago.
In the newly created world of mixed grassland and trees, around six million years ago, our own lineage Hominids (which currently includes five genera: Ardipithecus, Australopitecus, Praeanthropus, Paranthropus and Homo) appeared. Chimpanzees (Pan), which are anatomically close, also appeared in this time. The first hominid fossils date between 5.8 and 4.4 million years ago and have been assigned to the genus Ardipithecus. They may have lived in shady forest. Between about 3.9 and 3 million years, members of the genus Australopithecus were widespread in Eastern and North Africa. The first footprints of upright hominids walking on two legs are preserved in 3.7 million year old volcanic ash (from Laetoli in Tanzania). As hominids took their first, faltering steps, the long cooling trend was triggering the start of the Earth´s climate instability. The first stone tool use is recorded 2.6 million years ago. Between 2.2 and and 1.6 million years ago, Homo habilis (probably better reclassified as a member of the Australopithecus genus), were using stone flakes as tools, such as for claving meat off carrion. But they did not master the use of tools in hunting or defense, and were regularly preyed by large carnivorous cats.
Our genus, Homo, originated in the Great Rift Valley of East Africa, roughly two million years ago, during the relatively mild climate of the Pliocene Epoch. Homo erectus was the first undisputed member of our genus, with improved long distance walking and running ability. Homo erectus formed the first hunter-gatherer societies. When Northern Hemisphere ice ages began in earnest 1.8 million years ago (making the transition from the Pliocene to Pleistocene Epoch), a wet phase of African climate provided a corridor of familiar savannah habitat through which is currently a part of the Sahara desert. This allowed Homo erectus to make a relatively easy exit from East Africa, and they spread widely, both eastwards to Indonesia (Java) and China, and north-west to North Africa and Europe (Georgia). From this dispersed populations of Homo erectus, multiple hominid species appear to have evolved. These include Homo antecessor in southern Europe around 800 000 years ago and Homo heidelbergensis in central and northern Europe around 500 000 years ago. The heavily built Neanderthals (Homo neanderthalensis) may have evolved from Homo heidelbergensis in Europe, whilst the origins of tiny Homo florensiensis (from Flores, Indonesia) are currently being argued over (they may be a case of island dwarfism, descended from Homo erectus, although some of their features are more primitive). Homo erectus may have developed a form of “proto-language” as they formed larger larger social groups and their brain size increased. Early Homo transported stone for tool making up to 13 km, but after 1.2 million years ago, raw materials were transported greater distances of up to 100 km. It was Homo erectus that learnt to control fire. The controlled use of fire may date back as early as 1.5 million years ago, and evidence of its use for domestic purposes such as heating and cooking is scattered through the Pleistocene. By 800 000 years ago, hominids have learnt to create fire. Stone tool technologies also became more elaborate between about 400 000 and 250 000 years and brain size increased.
The stone age is divided in three periods: 600-100 BCE Old stone age; 100-50 BCE Middle stone age and 50-10 BCE New stone age. The glacial times were changed with interglacial:
600-540 1st ice time (Günz);
540-480 1st warm time (Günz-Mindel);
480-430 2nd ice time (Mindel);
430-240 2nd warm time (Mindel-Riß);
240-180 3rd ice time (Riß);
180-120 3rd warm time (Riß-Würm);
120-10 4th ice time (Würm).
Homo sapiens originated in East Africa around 200 000 ago, when the high Northern latitudes were in the grip of the penultimate ice age and Africa was particularly arid. The first fossils of anatomically modern humans come from Ethiopia. “Mitochondrial Eve” lived around 160 000 years ago. By around 100 000 years Homo sapiens had spread throughout Africa and into the Middle East (120 000 years ago he is present in Palestine), but other Homo species were still much more widespread, and Homo erectus, Homo neanderthalensis and Homo floresiensis all survived until remarkably recently during the last ice age. The FOXP2 gene, which is involved in speech and language, was fixed in the human population sometime during the last 200 000 years. Then by 130 000 years ago in Africa, raw materials for stone tool making were being transferred up to 300 km, beyond the range of any one group. Our ancestors emerged out of Africa and the Middle East and began to spread around the world around 65 000 years ago. The migration may have been facilitated by one of the periodic wet phases of the Sahara after a mega-drought in Africa from 135 000 to 90 000 years ago. The latest evidence suggests that modern humans first went East along a Southern coastal route through India and onward to Southern Asia and Australasia. An early offshoot from this migration led ultimately to the colonization of the Near East and Europe, but was stalled by unfavourable climate conditions in the lands bordering the Eastern shores of the Mediterranean, known as the Levant. Around 50 000 years ago technology became more sophisticated with the development of bone and antler tools, hunting became more specialized, long distance trade began, pigments were processed and artwork appeared, then our ancestors began ritually burying their dead. At some point during that interval, the ancestors of all of us humans alive today experienced a bottleneck in population of 10 000 or fewer breeding pairs. Members of this founding group have gone on to dominance. As modern humans arrived in new continents, many large mammal genera (over 40 kg) began to go extinct. Modern humans arrived in Australia sometime between 72 000 and 44 000 years and 14 of 16 genera went extinct. They reached Europe over 30 000 years ago where 9 of 25 genera went extinct.
In the whole, in this period the life developed modern forms: angiosperms and mammals became predominating on the Earth, at the end of period humans appear.
VIth period – 11 500 years ago till now.
Human societies have flourished during the Holocene Epoch, the current interglacial (warm period between ice ages) that started around 11 500 years ago.
Modern humans reached North America 11 500 years ago where 33 of 48 genera went extinct, and they continued to South America by 10 000 years ago where 50 of 60 genera went extinct. Our ancestors clearly played a part in these extinction. Extinction was less severe in Africa (8 of 44 genera).
Prior to the Holocene, abundant wild cereals were being collected, pounded and ground for food by members of the Natufian culture in the Levant. Then, perhaps in response to the drying effects of the Younger Dryas cooling 12 900 to 11 600 years ago on their regional ecosystem, people in this region domestical the first cereal crops, triggering the Neolithic revolution (12 000 to 10 000 years ago). Early in the Holocene, around 10 500 years, the Sahara re-entered one in its wet and green phases and the region encompassing the Nile, Euphrates and Tigres rivers, connected by the Levant, became the fabled Fertile Crescent. Farming arose independently in a number of other locations during the Holocene. Rice was domesticated in China, as early as 11 500 years ago. Maize (a C4) was domesticated somewhere in Mesoamerica, sometime before 7 000 years. The Andes and Amasonia, eastern North America, Sahel, tropical West Africa, Ethiopia, and New Guinea were also centres of domestication. Around 5000 years ago, a large scale climate change involving the drying and collapse of savannah ecosystems in the Sahara, brought a 200 year period of drought to the Middle East. Then the wetter conditions returned, but further interval of drought was about 4200 ago.
See also our “History of the world civilisation” Vol.1 §7 “Pre-civilisations”.
How many years will the Earth exist? We see that it is now in the 6th period of the Vth cycle, which corresponds to the age of 45-46 years. Vth cycle corresponds to the lower mental plane, VIth – to the higher mental plane (causal), VIIth – to the lower intuitive plane, VIIIth – to the higher intuitive plane, IXth – to the spiritual plane. So the Earth is now approximately in the middle of its existence and will exist 9 billion years in the whole (which corresponds to 90 years), if God will.
Richard Dawkins, Geschichten vom Ursprung des Lebens. 2. Aufl. Ullstein, Berlin 2010.
Tim Lenton and Andrew Watson, Revolutions that made the Earth, Oxford University Press, Oxford 2011.
Günther A. Wagner, Age Determination of Young Rocks and Artifacts, Springer-Verlag Berlin Heidelberg, 1998.
Г.А.Вагнер, Научные методы датирования в геологии, археологии и истории, Москва, Техносфера 2006.
Н.В.Короновский, В.Э.Хаин, Н.А.Ясаманов, Историческая геология, 2-е изд., М., «Академкнига», 2006.