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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.
At long irregular intervals, Earth's biosphere suffers a catastrophic die-off, a mass extinction, [9] often comprising an accumulation of smaller extinction events over a relatively brief period. [10] The first known mass extinction was the Great Oxidation Event 2.4 billion years ago, which killed most of the planet's obligate anaerobes.
Extinction Date Probable causes [2] Quaternary: Holocene extinction: c. 10,000 BC – Ongoing: Humans [3] Quaternary extinction event: 640,000, 74,000, and 13,000 years ago: Unknown; may include climate changes, massive volcanic eruptions and Humans (largely by human overhunting) [4] [5] [6] Neogene: Pliocene–Pleistocene boundary extinction: 2 Ma
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 percentage of megafauna on different land masses over time, with the arrival of humans indicated. Extinction of animals, plants, and other organisms caused by human actions may go as far back as the late Pleistocene, over 12,000 years ago. [57] There is a correlation between megafaunal extinction and the arrival of humans.
A growing number of scientists believe a sixth mass extinction event of a magnitude equal to the prior five has been unfolding for the past 10,000 years as humans have made their mark around the ...
[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 ...
More significantly, the current rate of global species extinctions is estimated as 100 to 1,000 times "background" rates (the average extinction rates in the evolutionary time scale of planet Earth), [71] [72] faster than at any other time in human history, [73] [74] while future rates are likely 10,000 times higher. [72]