８２ The History of the Earth #Past&Future #Universe

８２　The History of the Earth　#Past&Future #Universe

13.7 billion years ago Big Bang
13.5 billion years ago Birth of stars and Milky Way galaxy [1]



※ [2]

4.6 billion years ago　　Formation of The Solar system and Earth (primitive atmosphere is mostly hydrogen and helium).
4.3-4.0 billion years ago 　Ocean was born 
3.8 billion years ago Birth of unicellular organisms 
2.4～2.1 billion years ago The oldest ice age. （Huronian glaciation）
750～700 million years ago Sturtian glaciations
640 million years ago Marinoan glaciation・・・Snowball Earth



※The Snowball Earth [3]

600 million years ago Birth and explosion of multicellular organisms（the Cambrian）
500 million years ago　　Creature won the brain.
460～430 million years ago Little ice age(Andean-Saharan glaciation)
・・・Two events occurred that killed off 60% to 70% of all species. [4]
※Other causes ：Gamma ray burst caused by supernova explosion occurred within 6000 light years
400 million years ago Plants advanced the land from the sea.
375 ～360 million years ago Expansion period of glacier( Karoo Ice Age）
　　　・・・a prolonged series eliminated at least 70% of all species [4]
・・・There are also theories that the collision of asteroids is the cause of extinction.
360 million years ago Animal’s landing 
300 million years ago 　　Increase of insects (cockroaches = living fossil)
Emergence of reptiles
250 million years ago Mass extinction of lives (Permian)
・・・Earth's largest extinction killed 90% to 96% of all species [4]
230 million years ago Emergence of dinosaurs
225 million years ago　　 Emergence of mammals 
220 million years ago 　　Mass extinction of lives 
・・・75% of all species became extinct [4]
150 million years ago 　　Emergence of archaeopteryx 
140 million years ago 　　Division of Australian continent
100 million years ago 　Golden age of dinosaurs (The average temperature was about 23℃. Temperature of current average is 15℃.)
66 million years ago Mass extinction of organisms= Extinction of dinosaurs(Collision of comet(about 10km diameter))
[4]
・・・75% of all species became extinct. [4]
Emergence of primates(Ability to synthesize vitamin C is lost)



40 million years ago Last ice age
25 million years ago The oldest fossil that seems to be apes
10 million ～5 million years ago The formation of the Great Rift Valley in Africa began.
about 6 million ～ 5 million years ago The differentiation of Humans and chimpanzees
about 2.5 million ～ 1.8 million years ago　　Start of Stone tools
1.7 million years ago　　Human beings born
780,000 years ago The last pole shift of Geomagnetism
500,000 years ago　　Peking man
230,000 years ago 　 Emergence of Neanderthals ・・・Use of stone tools
200,000 ～190,000 years ago 　Emergence of Homo sapiens (present people)
160,000 ± 40,000 years ago 　 Mitochondrial Eve in Africa
(150 000 years ago 　 polar bear and brown bear was divided)
100,000 years ago～ Modern humans (Homo sapiens) were spread out of the Africa.
(It was lower about 5-8 degrees in average temperature than the current：The difference between the annual average temperature in Tokyo and Sapporo. Sea level was 120m lower than now. )
70,000 years ago ～ 　The last ice age
10,000 years ago　　　The end of the last ice age
30,000 years ago 　 Extinction of Neanderthal 
30,000 ～ 20,000 years ago Mongoloid passed to the Americas.
14,000 ～10,000 years ago Humanity tamed the dog.
13 000 years ago 　Japanese archipelago became the island.
10,000 years ago 　The end of the last ice age 

A.C. 800 - 1300 The average temperature is higher than the present by 1 ° C or more. In the United Kingdom grapes were grown, Greenland was not covered with ice. [5]

20th century　　Development of science and technology, the explosive growth of population, globalization, world war, environmental destruction and resource depletion concerns
The 21st century 　　 Nuclear fusion power generation. Development of Artificial intelligence, Biotechnology and Nanotechnology. Multi-polar world.

【References】
1. Milky Way - Wikipedia
2. Chronology of the universe - Wikipedia
3.Credit: Stocktrek Images, Inc. / Alamy
4. Mass Extinction Event - Wikipedia
5.Michael Le Page”Climate myths: It was warmer during the Medieval period, with vineyards in England”at newscientist.com 20070516
https://www.newscientist.com/article/dn11644-climate-myths-it-was-warmer-during-the-medieval-period-with-vineyards-in-england/