The Moon formed 4.533 billion years ago, probably as the result of a protoplanet impacting the Earth with about 10% of the Earth's mass (giant impact hypothesis, or the big whack or the big splash). The protoplanet is sometimes called Theia (or Orpheus or Hephaestus), derived from Greek mythology, as Theia was the Titan who gave birth to the Moon goddess Selene.
Initially molten, the outer layer of the planet Earth cooled to form a solid crust when water began accumulating in the atmosphere. Outgassing and volcanic activity produced the primordial atmosphere. Condensing water vapor, augmented by ice delivered by comets, produced the oceans.
The continents migrated across the surface, occasionally combining to form a supercontinent. Roughly 750 million years ago, the earliest known supercontinent, Rodinia, began to break apart. The continents later recombined to form Pannotia, 600 to 540 mya, then finally Pangaea, which broke apart 180 million years ago.
The present pattern of ice ages began about 40 million years ago, and then intensified during the Pliocene about 3 million years ago. The polar regions have since undergone repeated cycles of glaciation and thaw, repeating every 40,000 to 100,000 years. The last ice age ended 10 000 years ago.
* * * Cambrian explosion/radiation * * *
The highly energetic chemistry is believed to have produced a self-replicating molecule around 4 billion years ago. The last universal ancestor (LUA), also LUCA (last universal common ancestor), is the hypothetical latest living organism from which all currently living organisms descend. It is estimated to have lived some 3.6 to 4.1 billion years ago. [Doolittle, W. Ford (February, 2000) "Uprooting the tree of life", Scientific American 282 (6): 90-95].
It has been hypothesized that severe glacial action between 750 and 580 million years ago, during the Neoproterozoic, covered much of the planet in a sheet of ice. This hypothesis has been termed "Snowball Earth", and is of particular interest because it preceded the Cambrian explosion/radiation (around 540 million years ago), a rapid appearance of most major groups of complex animals in the fossil record. 580 million years ago, multicellular life forms began to proliferate, and in the following 70/80 million years the rate of evolution accelerated, and the diversity of life began to resemble today's.
Following the Cambrian explosion, five major extinctions events took place when over 50 % of animal species died: End Ordovician, Late Devonian, End Permian (Earth's largest extinction), End Triassic, and End Cretaceous extinction (65 million years ago, when a meteorite collision probably triggered the extinction of the dinosaurs and other large reptiles, but spared small animals such as mammals. There probably were mass extinctions in the Archean and Proterozoic Eons, but before the Phanerozoic there were no animals with hard body parts to leave a significant fossil record.
In addition, most of biologists view the present era as part of a mass extinction event, the Holocene extinction, possibly one of the fastest ever. In broad usage, the Holocene extinction event includes a notable disappearance of large mammals, known as megafauna, by the end of the last glacial period 9 000 to 13 000 years ago, which is referred to as the Pleistocene extinction event or Ice Age extinction event.
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Apparent extinction intensity, the fraction of genera going extinct at any given time, as reconstructed from the fossil record. (Graph not meant to include recent epoch of Holocene extinction event) Marine fossils are mostly used to measure extinction rates because they are more plentiful and cover a longer time span than fossils of land organisms.
Great tectonic changes occurred in the late Miocene era (8 to 10 million years ago), which resulted in Africa's Great Rift Valley. It was an insurmountable barrier for early primate populations, physically separating the ancestors oh humans from those of the anthropoid apes. Climatic changes were also underway: the world was cooling down, and ice caps across the polar regions locked up huge quantities of water. Africa developed a seasonal climate, and the vast rainforests shrank and were replaced by the savannah. The Great Rift Valley acting as a watershed, the water from the Atlantic Ocean wasn't reaching the west of the Rift, which was to be a monsoon zone most dominated by drought. Some scientists believe the isolation of the apes living east of the Rift have made them adapt rapidly.
They developed the upward stance, which made them easier to look for dangers and to carry food and objects.
7 million years ago, the first 2 primates (Toumaä in Tchad and Orrorin in Kenya) came down the trees, probably due to drought, and could stand on their feet.
2 million years later, another species of primates, the Australopithecine, also came down the trees, and lived in oriental and austral Africa. The earliest of the Australopithecines discovered date back about 4.2 million years. They do not belong to the gender homo.
3 millions years later, in the same region, 2 of his descendants Homo habilis and Homo Rudolfensis, stood more straight; they could therefore carry a heavier brain, and they trim stones. They also travel from region to region on the African continent.
About 2.5 million years ago, when the ice age was getting underway, renewed drought made living conditions difficult, triggering 2 evolutionary responses: the robust branch of australopithecines developed a stronger chewing apparatus, and another relied increasingly in versatility and inventiveness, the line that produced the first representative of the gender homo.
One theory claims that the earliest homo species was Homo rudolfensis, dating back about 2.5 million years, who was contemporary with the last Australopithecus. Homo rudolfensis had double the brain capacity of Australopithecus.
Homo erectus is thought to have mastered fire about 1.5 million years ago.
Only survived the primates which were the most suitable for wandering.
1.5 million years ago, in East Africa, Homo ergaster appeared among the existing primates. He is more suitable for travels and running than the others. He may have acquired the technique of language.
1 million year ago, Homo erectus appeared as a descendant of Homo ergaster; he leaved Africa for the first time and covered Europe, Central Asia, India, Indonesia and China.
Descending from Homo erectus (the stone tool technology was very close to that of the Acheulean tools used by Homo erectus), Homo heidelbergensis (the "Heidelberg Man", named after the University of Heidelberg) may be the direct ancestor of both Homo neanderthalensis in Europe and Homo sapiens. The best evidence found for these hominin date between 600,000 and 400,000 years ago.
Sometime during the Paleolithic, primates developed early language (some 500 000 years ago), music, early art (the earliest possible artwork yet discovered, the Venus of Tan-Tan Discovered in Morocco, dates from between 500 000 and 300 000 BP).
They realized that forces of nature can service them. They invented shoes and clothes. They also began to pass the knowledge from generation to generation.
Homo sapiens harnessed the force of thunder and learned how to make fire. He could then cook vegetables, and therefore feed his brain better. He also invented the first shoes and clothes, and went to Europe which had a colder climate.
Cro-Magnons relate to Homo sapiens; they have been named after a cave in Dordogne (region of south-west France).
300 000 years ago, Homo sapiens evolved into 2 branches, with at first the Neanderthals (Homo neandertalis) and then the co-existing Homo sapiens sapiens.
At this time, Homo sapiens started to build huts and to bury his dead systematically. Cannibalism also started, not as an act of violence but as a ritual to get the force of the dead.
Sexuality and reproduction also began to get differentiated.
The Recent African Origin (RAO), or "out-of-Africa", hypothesis proposes that modern humans (Homo sapiens sapiens) have emerged about 130 000 years ago in Africa and later migrated outwards to replace hominids in other parts of the world (like the Neanderthals). Evidence from Archaeogenetics accumulating since the 1990s has lent strong support to RAO and has marginalized the competing multiregional hypothesis (which proposed that modern humans evolved, at least in part, from independent hominid populations).
Towards 160 000 BC, the first Homo sapiens sapiens appeared. He had a much more sophisticated brain, and lived in larger tribes in which women are responsible of the education of the children. Cannibalism still widely existed.
The average life expectancy was 25 years. Human groups travelled to Europe and Middle-East. They did not accumulate resources, did not keep anything in reserve; they did not own anything that could not be transported. The first exchanges were set up (with the beginning of slavery): objects, women and prisoners.
According to the Toba catastrophe theory, 70 000 to 75 000 years ago, the Toba caldera, on Sumatra, underwent an eruption of category 8 ("mega-colossal") on the Volcanic Explosivity Index; it has probably lowered the average global temperature by 5 degrees Celsius for several years and may have triggered an ice age. It reduced the world's human population to 10 000 or even a mere 1,000 breeding pairs, creating a bottleneck in the various species that existed at the time. This in turn accelerated differentiation of the isolated human populations, eventually leading to the extinction of all the other human species except for the two branches that became Neanderthals and modern humans. According to this theory, humans once again fanned out from Africa after Toba when the climate and other factors permitted.
They migrated first to Arabia and India and onwards to Indochina and Australia some 60 000 years ago, northwestwards into Europe and eastwards into Central Asia some 40 000 years ago (when climate got warmer), and later to the Middle East and what would become the Fertile Crescent following the end of the Würm glaciation period (70 000-10 000 years BP). Different theories date the migration to North America to either 40 000 years ago or the end of the last Ice Age, 12 000 years ago.
Towards 45 000 years ago, humans live in caves during winter and in huts during summer.
The division of labour is established between the different group members.
Around 30 000 years ago, all primate species disappear quickly but Homo sapiens sapiens - the reason is unknown.
Cannibalism is beginning to be replaced by rites and religious sacrifices. Taboos are established (e.g. eating certain plants, incest).
Life expectancy reaches 30 years, which gives more time to transmit knowledge to future generations.
The idea of God is dissociated into several categories owing to the natural elements at play: fire, wind, earth, rain, etc. Polytheism is a religious form that comes from a primitive monotheism. The sacred principles help shape the political ones. It is the beginning of the Ritual Order.
20 000 years ago, the most advanced primates go to the Middle-East in Mesopotamia, whose climate was particularly welcoming. The groups were settling for longer periods, building the first houses made of stone.
They were controlling large herds of animals, without domesticating them though.
In some areas, such as the Near East, agriculture was already underway by the end of the Pleistocene (period on the geologic timescale, from 1 808 000 to 11 550 years BP, intended to cover the world's recent period of repeated glaciations). In areas with limited glacial impact, the term Epipaleolithic is sometimes preferred. Regions that experienced greater environmental effects as the last ice age ended have a much more evident and longer Mesolithic era. In Northern Europe, societies were able to live well on rich food supplies from the marshlands fostered by the warmer climate. Such conditions produced distinctive human behaviours which are preserved in the material record, such as the Maglemosian culture (of Northern Europe; in Scandinavia, it is succeeded by the Kongemose culture) and the Azilian one. These conditions delayed the coming of the Neolithic until 4 000 BC in northern Europe.
The Mesolithic is characterized by small composite flint tools (dark form of mineral quartz). These technologies first occur in Africa, associated with the Azilian cultures (which settled in the south of Spain about 13 000 BC; Azilians were named before the Mas d'Azil cave), before spreading to Europe through the Ibero-Maurusian culture of Spain and Portugal, and the Kebaran culture of Palestine. Independent discovery is not ruled out though.
The Sumerians first began farming about 9 500 BC. By 7 000 BC, agriculture had spread to India; by 6 000 BC, to Egypt; by 5 000 BC, to China. About 2 700 BC, agriculture had come to Mesoamerica. Although attention has tended to concentrate on the Middle East's Fertile Crescent, archaeology in the Americas, East Asia and Southeast Asia indicates that agricultural systems, using different crops and animals, may in some cases have developed there nearly as early.
Around 7750 BC the waters of the Mediterranean broke through the Bosphorus strait into the Black Sea, whose coastline shifted more than 1 km inland. The displaced tribes migrated up the River Danube towards Central Europe, spreading the knowledge of agriculture. Most of the early cultivated plants (like emmer wheat and barley) didn't naturally grow in central Europe. Some nomadic peoples, such as the Indigenous Australians and the Bushmen of southern Africa (those were traditionally hunter-gatherers, who started to switch to farming in the 1950s), did not practice agriculture until relatively recent times.
People began to domesticate animals soon after the introduction of agriculture, starting with pigs (which found food in the surrounding woods), then cattle, sheep and goats. Dogs, which had been domesticated from wolves or jackals, proved useful at hunting, then after its decline, at guarding herds and acting as watchdogs. Sheep and goats originate from the Near East.
Pottery was also invented during the Neolithic era; knowledge of the ceramics spread across Europe from the Near East by about 4 000 BC.
Structures made of large stones appeared mainly in the Neolithic era (a bit before as well), prospering between the years 4 200BC and 3 500 BC; this Megalithic period is characterized by great building projects serving a special purpose (often associated with tombs), and performed by people from many parts of the world living in many different periods.
Agriculture made possible dense and sedentary populations, who lived longer and had more time, therefore leading to complex societies and cosmogonies. States and markets emerged. Technologies enhanced people's ability to control nature and to develop transport and communication. It was the beginning of civilisations.
based on:
A short history of the world - H.G. Wells (1920)
Une brève histoire de l'avenir - Jacques Attali (2006)
Wikipedia & other sources on the internet
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