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The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species indicate that they have diverged through the ...
The earliest evidence for life on Earth includes: 3.8 billion-year-old biogenic hematite in a banded iron formation of the Nuvvuagittuq Greenstone Belt in Canada; [30] graphite in 3.7 billion-year-old metasedimentary rocks in western Greenland; [31] and microbial mat fossils in 3.48 billion-year-old sandstone in Western Australia. [32] [33 ...
The diversity of life on Earth is a result of the dynamic interplay between genetic opportunity, metabolic capability, environmental challenges, [90] and symbiosis. [91] [92] [93] For most of its existence, Earth's habitable environment has been dominated by microorganisms and subjected to their metabolism
The first English use of the expression "meaning of life" appears in Thomas Carlyle's Sartor Resartus (1833–1834), book II chapter IX, "The Everlasting Yea". [1]Our Life is compassed round with Necessity; yet is the meaning of Life itself no other than Freedom, than Voluntary Force: thus have we a warfare; in the beginning, especially, a hard-fought battle.
Human history is the record of humankind from prehistory to the present. Modern humans evolved in Africa around 300,000 years ago and initially lived as hunter-gatherers.They migrated out of Africa during the Last Ice Age and had spread across Earth's continental land except Antarctica by the end of the Ice Age 12,000 years ago.
The world has hundreds of major cities, mostly in coastal regions. According to the latest official data, the world population is 8,179,580,000 people. As of 2022, the world had 159 metropolitan areas with a population of over 3,000,000 people each. [31] As of 2010, about 3 billion people live in or around urban areas. [8]
Evolution of live birth , with early therians probably having pouches for keeping their undeveloped young like in modern marsupials. Nipples stemmed out of the therian milk lines. The posterior orifice separates into anal and urogenital openings; males possess an external penis.
Overview map of the peopling of the world by early humans during the Upper Paleolithic, following the Southern Dispersal paradigm. The so-called "recent dispersal" of modern humans took place about 70–50,000 years ago. [60] [61] [62] It is this migration wave that led to the lasting spread of modern humans throughout the world.