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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 ...
Date Event 4.3-4.1 Ga: The earliest life appears, possibly as protocells. Their genetic material was probably composed of RNA, capable of both self replication and enzymatic activity; their membranes were composed of lipids. The genes were separate strands, translated into proteins and often exchanged between the protocells.
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.
The key to life history theory is that there are limited resources available, and focusing on only a few life history characteristics is necessary. Examples of some major life history characteristics include: Age at first reproductive event; Reproductive lifespan and ageing; Number and size of offspring
The geologic time scale, proportionally represented as a log-spiral with some major events in Earth's history. A megaannus (Ma) represents one million (10 6) years.. The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth.
Following is a comparison of the growth of cycle 25 versus cycle 24, using the 13-month sunspot averages, beginning with the months of the respective minimums. Numbers in brackets for cycle 25 indicate the minimum possible value for that month, assuming there are no more sunspots between now (Feb 20, 2025) and six months after the end of the ...
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