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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.
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 Rare Earth hypothesis argues that planets with complex life, like Earth, are exceptionally rare.. In planetary astronomy and astrobiology, the Rare Earth hypothesis argues that the origin of life and the evolution of biological complexity, such as sexually reproducing, multicellular organisms on Earth, and subsequently human intelligence, required an improbable combination of astrophysical ...
Nuclear war is an often-predicted cause of the extinction of humankind. [1]Human extinction or omnicide is the hypothetical end of the human species, either by population decline due to extraneous natural causes, such as an asteroid impact or large-scale volcanism, or via anthropogenic destruction (self-extinction), for example by sub-replacement fertility.
Life forms live in every part of the Earth's biosphere, including soil, hot springs, inside rocks at least 19 km (12 mi) deep underground, and at least 64 km (40 mi) high in the atmosphere. [26] [27] [28] Marine life under many forms has been found in the deepest reaches of the world ocean while much of the deep sea remains to be explored. [29]
The rate of species loss is greater now than at any time in human history, with extinctions occurring at rates hundreds of times higher than background extinction rates. [35] [38] [39] and expected to still grow in the upcoming years. [39] [40] [41] As of 2012, some studies suggest that 25% of all mammal species could be extinct in 20 years. [42]
[47] [48] Brain expansion (enlargement) between 0.8 and 0.2 Ma may have occurred due to the extinction of most African megafauna (which made humans feed from smaller prey and plants, which required greater intelligence due to greater speed of the former and uncertainty about whether the latter were poisonous or not), extreme climate variability ...
The worst Phanerozoic event, the Permian–Triassic extinction, devastated life on Earth, killing over 90% of species. Life seemed to recover quickly after the P-T extinction, but this was mostly in the form of disaster taxa, such as the hardy Lystrosaurus. The most recent research indicates that the specialized animals that formed complex ...