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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.
As for life on land, in 2019 scientists reported the discovery of a fossilized fungus, named Ourasphaira giraldae, in the Canadian Arctic, that may have grown on land a billion years ago, well before plants are thought to have been living on land. [99] [100] [101] The earliest life on land may have been bacteria 3.22 billion years ago. [102]
The scientists argue that the current model overemphasizes how often an amino acid appeared in an early life form, leading to a theory that the amino acid found in the highest saturation must have ...
The first “fossils” pointing toward complex life in this basin were discovered in 2008, and since then, other scientists have put forward theories suggesting that the specimens were simply ...
Now, scientists from Harvard University have discovered how cloud-to-ground lightning strikes—especially volcano-produced ones—could’ve created the necessary ingredients for life more ...
If the deep marine hydrothermal setting was the site for the origin of life, then abiogenesis could have happened as early as 4.0-4.2 Gya. If life evolved in the ocean at depths of more than ten meters, it would have been shielded both from impacts and the then high levels of ultraviolet radiation from the sun.
[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 ...